Procedure for leaching valuable metals out of ore at presence of hydrochloric acid
SUBSTANCE: procedure consists in following stages: ore leaching at presence of hydrochloric acid with production of soluble metal chloride in solution for leaching, addition of sulphuric acid into solution for leaching, extraction of metal sulphate from solution for leaching and regeneration of hydrochloric acid. As ore there is used oxide ore of non-ferrous metal, such as oxide zinc ore, laterite nickel ore such as saprolite or limonite, sulphide ore or titanium ore. Valuable metal is chosen from group including Zn, Cu, Ti, Al, Cr, Ni, Co, Mn, Fe, Pb, Na, K, Ca, metals of platinum group and gold. Valuable metal or less valuable metal, such as magnesium, can be metal in composition of metal sulphite. Regenerated hydrochloric acid is directed into re-circulation system into process of leaching.
EFFECT: raised efficiency of procedure.
40 cl, 36 dwg, 5 tbl
Background of invention
The present invention relates to a method for processing salt chloride solution, in which there is accumulation or regeneration of hydrochloric acid, and to a method for leaching of metals from ores chloride solution. The method is economical and acceptable from an environmental point of view hydrometallurgical process for extraction of valuable metals from ores or concentrates.
It is known the use of relatively concentrated salt chloride solutions in the quality environment for leaching of base metals, one of the last options method includes hydraulic extraction of copper Outokumpu described in several patents, such as WO 2003/35916, WP 2003/89675 etc. it is Known that chloride salt solutions of high ionic strength mainly provide faster and more complete leaching compared with conventional relatively dilute sulfate environment. However, removing the dissolved valuable materials from such salt solutions is a time-consuming process and eliminates the standard electrolytic processing.
For many years research in many institutions were focused on the use of hydrochloric acid (chloride environment) for leaching of Nickel from lateritic ores, first of all, we should mention the work in this field is t, held at the University. Nmisa in grids (N.M.Rice of Leeds University (see Rice 1989). When processing both types of ore, typical silicate (serpentine) and oxide ore (limonite or lake ore)was observed optimal kinetic parameters, which indicated the possibility of applying this system to the leaching of valuable metals such as Nickel, from a number of materials such as laterite. Of particular interest is the rapid kinetics (1 h) leaching at high temperatures, usually over 80°C, 4 M hydrochloric acid solution. Was developed conceptual framework (Rice and Strong, 1974) using leaching with hydrochloric acid to solubilize the valuable cobalt and Nickel, which are then removed by solvent extraction with subsequent hydrolysis and received in the form of Nickel hydroxide (using magnesia as a neutralizing agent), respectively. The main components that contribute to the consumption of the expensive hydrochloric acid, are impurities such as iron and magnesium. The iron chloride is removed from the solution by solvent extraction and processing at the stage of firing, by sputtering, thereby forming a stable hematite and regenerated hydrochloric acid, which is directed into the recirculation system to the stage of leaching. Similarly, the magnesium chloride is treated at the point the burning spray, this produces magnesia (which is used as a commercial by-product and/or used as a neutralizing agent) and regenerated hydrochloric acid (returns to the recirculation system through leaching).
Found that approximately 70% of the world's natural reserves of Nickel contained in the laterite ore. Currently, only about 40% Nickel, produced in industry, extracted from laterite ores, and it is expected that by 2012 this figure will increase to approximately 50% (calculations Dalvi and others, 2004). Thus, currently, there is a need to develop a new process for extraction of Nickel and cobalt from laterite deposits, which are characterized by significantly lower performance characteristics and, above all, lower capital costs compared with modern technologies. Moreover, taking into account reserves and future growth needs of Nickel approximately 4% (depending on various factors) the demand for Nickel will be 40000-45000 tons per year produced in the Nickel industry, to meet the needs (accounts Dalvi and others, 2004). Even if you use the additional development of new sources (stocks) of small sulfide deposits, VI is e projects providing new ways of development of laterite (such as acid leaching at high pressure Goro and Ravensthrope, new casting furnace such as furnace Koniambo, and new ways sulfide hydrometallurgical processing, such as the way "Voisey''s Bay"), all of these methods will not be able to meet the needs.
Geology and Mineralogy
Economical processing of laterite largely depends on the quality and composition of the processed ore. Lateritic Nickel deposits include two basic layer (horizon), that is limonadovy (hydrated iron oxide) surface material (low content of Nickel and magnesium, high iron content) and a deeper layer saprobity (hydrosilicate magnesium) material (high content of Nickel and magnesium, low iron content). These layers are formed by erosion of the original rock, which in turn is formed of crystallized melt rocks in the form of minerals Fe-Mg-Si-o Source the rock contains Ni (~0<2%) and, as these metals can substitute for Fe and Mg (the same valency and radius of the ions) in the crystal lattice of the above silicates. Primary serpentine minerals, Mg3(Si2O5)(OH)4formed from the source rocks are in the process of serpentinization at elevated temperatures and Yes the relocation (in the presence of water beneath the earth's surface). This process leads to the natural enrichment of Nickel (<0.5% of Ni). As a co-product in the specified process of serpentinization also formed magnetite, which is, apart from some source rock (such as olivine), the main source of Fe in the erosion process. Lateritization happens if the primary serpentine (the content of which depends on the degree of serpentinely) and associated remains of the original rock (primarily minerals, such as olivine) are subjected to continuous erosion, primarily in humid tropical regions (so-called process of lateritization) on the earth's surface or in the surrounding layers. In the process of lateritization Ni and Co are concentrated in the 3-30 times compared to the original breed. The process of lateritization is dynamic, and deep incision is essentially a snapshot, and in the lower layer is relatively recently changed the breed, i.e., surface water (zakislyaetsya when dissolved CO2and organic acids) dissolve and videlicet Ni, Mg, Si, Fe (as Fe2+) and Al (in order to reduce mobility) as water percolates through the deep incision. In the surface layers of iron rapidly oxidizes and precipitates as amorphous iron hydroxide (III), in this structure, together adsorbed Ni typically 1.5% Ni) and almost all With:
* - The specified process is a non-equilibrium reaction, which indicates the complexity of the deposition process in nature. Fe2+leached and dissolved in the oxidizing conditions of both types of iron oxides such as magnetite, maghemite etc., and silicates of Mg(Fe), such as olivine and orthopyroxene. The newly formed solid substance (indicated on the right) likely includes the precipitated iron hydroxide (Fe(OH)3in an intermediate phase.
Over time, the crystallinity of the material is improved and formed the first form of goethite (the main component of the oxide deposits) and gradually transforms (with the top layers to the bottom) in the most stable natural form, i.e. in hematite. In the crystal lattice of hematite in the wet oxidation of Ni-laterite environment cannot accumulate Ni and Co, while reducing its quality and forms the upper crust, the so-called ferricrete (layer, which is removed when the first development of lateritic deposits). It is important to note that Ni and, above all, With also significantly adsorbed by mineral oxides/hydroxides of Mn (mainly generated in the form of veins or superficial deposits of other minerals). Field Goro in New Caledonia and the Deposit of Moa Bay in Cuba are examples of sediment, which is mainly comprised of the specified type limonadovy zone in the deep section.
Many Leonidovich deposits formed when excess of free silicon in the composition of the original rock) re-deposited after leaching of Mg-silicate structure (serpentine, olivine, and so on) in the form of microcrystalline chalcedony quartz. Usually these processes occur due to changes in Eh and/or pH in the deep section. Microcrystalline chalcedony quartz in most cases re-crystallizes into a more crystalline phase of silica, the formation of free individual silica particles from small to large in size (examples ores of this type are silicate deposits Ravensthorpe and Jacare, i.e. ores of this type are subjected to enrichment using physical removal of large particles of quartz).
In milder conditions, erosion, for example in terms of dry or cold climate, or limited movement of groundwater (poor drainage) the degree of leaching is reduced, and kristallicheskoi patterns of serpentine and olivine mostly leached magnesium. The result is a simultaneous enrichment of other less mobile components of minerals, such as Fe and Si, which leads to the transformation of primary serpentine and olivine in a smectic clay. Fe2+is less movable than Mg2+and thus replace the AET Mg in the crystal structure of the newly formed smectic clay. Thus, these clay Mg, Fe differ in composition from enriched in magnesium sepiolites to iron-fortified of nontronites. Deposits of clay (if present) are usually between limonadovy and saprolite areas. Minerals smectic clay also record Ni (more than 1.5% Ni) in the crystal lattice, where the Nickel ions replaces Fe2+and Mg2+in magdalaine positions. For the formation of smectic clay requires access to the silicon, which is present as inclusions microcrystalline chalcedony quartz in the clay. An example of such a Deposit is a Deposit Murrin, which contain in the deep section interspersed smectic zone.
Regardless of the presence or absence of a layer of smectic clay residual Ni, Mg, Fe and Si into solution. With decreasing groundwater levels the pH increases due to reactions with neviperenni rocky soil. Near laterite mainland rock with a modified surface section are formed is enriched in Nickel (20% Ni) hydrated Mg-silicate minerals (known as garnierite). Nickel re-deposited at more alkaline pH compared with magnesium, which results in enrichment of Nickel Mg-silicates, the result is the formation of so-called garnierite (enriched in Nickel hydrated Mg-silicates). Garnierite on is more common in tectonically active layers, such as New Caledonia, and rarely found in cratonic regions, such as Brazil or Western Australia. The Nickel content in the source rock (ground) largely determines the Nickel content in the formed laterite ores. Between mainland soil or a layer of garnierite (if present) and a layer of limonite or clay (if present) is located in a transition zone containing substantially modified magnesium silicate material called saprolite area, i.e. containing minerals phyllosilicates groups, which are formed from the primary serpentine and source rocks. When erosion reservationservice source rocks can also be formed microcrystalline chalcedony quartz, occurring in the most permeable geological structures, such as zones of transverse shear, faults, veins and cracks. Over time, Fe and, above all, Ni (usually 2-3% Ni) replace Mg with secondary education "modified" serpentines. For example,
To shift the equilibrium reaction to the right, it is necessary that the concentration of Nickel in penetrating groundwater was not much higher than in the solid phase.
Nickel begins to replace the magnesium is preferably in the areas of the weaker links in the serpentine structure, i.e. in the position HE ties those who reticence patterns (the so-called layer brucite).
And finally, as a result of uneven erosion (incision) laterite horizon, and also due to the uneven development of individual samples of ore, such as saprolite, can contain various amounts of other ores, such as limonite and/or clay. Thus, the ore as raw material is characterized by extremely variable mineralogical composition and associated characteristics processing.
The main sources of lateritic Nickel all over the world contain ore lemontovo type and to a lesser extent ore saprolites type (Monhemius, 1987 and Elias, 2002).
It should again be noted that in the processing of Nickel ore of high quality, the most reasonable is the efficiency of any process used. An important stage in the processing as possible is enrichment. Unfortunately, both types of ores, limonite and saprolite, difficult to enrichment, as Ni homogeneous mixed with the minerals goethite and magnesium silicate, respectively. There is a certain possibility of enrichment, but only if there is a large barren material. Screening such a large material is possible only if it is characterized by a low content of Ni, such as large quartz, magnesite (MgCO3) and magnesium silicate, etc.
The melting process (Fig 1)
1 shows a diagram overtime is and saprolite method of melting. The ore contains 20-50% of free water and at the first stage it is removed by drying. Then the ore is calcined to remove the structured water with subsequent recovery of Ni and Fe to the metals in the furnace mixed with coke or coal. Mg, Si, etc. form a slag, which allows you to remove the liquid molten alloy of Ni-Fe. Then you need refining (remelting) to remove residual S, and Si: adding lime forms a slag CaS, and when the air oxidation occurs turning With gaseous CO and Si oxide in the slag. If you get ferro-Nickel, then a small amount of Fe oxidizes in the slag, as ferro-Nickel is used to produce stainless steel. When using the production method of the matte require adding S in the kiln in reducing conditions. When this occurs, the interaction with the metal Ni and (unwanted) interaction with Fe to form sulfides. This material is then melted, and the oxides form a slag, and sulfides form a Stein. Finally, through this purge air for oxidation of the base Fe to slag.
Features of the method:
the melting point of the slag depends on SiO2/MgO and FeO;
- and the variability of the ore composition has to be neutralized to provide specified as the target materials (development and ore averaging increase costs;
- marginal economic indicators of the quality of ore for projects "brown field" (brownfield - redevelopment of old enterprises) with a low value of approximately 1.7% of Ni, and for projects "brown field" with the high cost approximately 2.1% of Ni (Dalvi and others, 2004), that is, the process limits the performance of materials that can be used as the target ore;
- the disadvantages of the melting process include high investment and energy costs, the economy of the process largely depends on regional energy prices;
although the extraction of Ni is quite high (~90%), the exit as a by-product or is too small or completely absent, firstly, due to the low Co content in saprolitic ores and, secondly, due to the low extraction (~50%) (Dalvi and others, 2004).
The process Caron (2)
First, the ore is dried in a rotary kiln and fired in reducing conditions (usually as a reductant used oil fuel). Ni and selectively restored at approximately 700°C to metals (approximately 10% of the Fe is partially restored). If the silicate content in the substrate is increased (due to processing more saprolite ore), then re-Krista is a zation of forsterite (amorphous Mg-silicate) (which hardly recovered at 700°C) and when this occurs, the capture of Ni, that is, the Nickel is not amenable to leaching. Similarly higher temperature recovery and excess recovery leads to increased educational opportunities refractory phase (subject to leaching in the system ammonia-ammonium carbonate), that is, the process boils down to the kinetics depending on the extraction of Ni and Co. After cooling, the alloy is leached in an atmosphere of air in an oxidizing environment (air) in a solution of ammonia-ammonium carbonate (pH ~10). Leached Ni (Co) and Fe form extremely durable linecomplete in solution. Ion iron (II) is oxidized to iron (III) and hydrolyzed to form gelatinizing hydroxide iron (together With precipitated with iron hydroxide, and a significant portion is not subject to recovery). After separation system liquid - solid certain amount of Ni and With all deposited in the form of sulfides in the presence of gaseous H2S (is less soluble compared to Ni, but due to the high ratio of Ni:Co is a partial precipitation of Ni). A solution of Ni (free) then evaporated with steam, forming a basic carbonate Ni (solid phase), and CO2and ammonia in the gaseous phase. CO2and ammonia is recovered for reuse in the absorption by water with formation of a solution of ammonia-ammonium carbonate. KEK carbonate is icela or used as a commercial product, or subjected to further processing using a variety of methods end processing to extract Ni from carbonates or from solution. Ni and recovered by solvent extraction, or basic carbonate calcined in a rotary kiln with the formation of NiO (product with a low degree of purification). In another embodiment, the filter cake is again dissolved in a solution of ammonium sulfate with the formation of sulfate Nickel-ammonium, which is then reduced to metallic Nickel in the presence of gaseous hydrogen (see Monhemius, 1987).
Features of the process:
although this method can be used for processing larger numbers of some types of saprolite (compared with the method of acid leaching at high pressure), high concentrations of Mg and silicate forms increases the number of forsterite, which leads to increased losses of Nickel;
although most of the reagents (ammonia and CO2) enters the recirculation system process, there is considerable loss (primarily due to the leaching of magnesium, i.e. the formation of carbonate Mg-ammonium), in addition, require auxiliary reagents to obtain a product with a relatively high degree of purification;
more than 60% of the total consumed energy is used in the preliminary stages of the process (drying wet ore and the recovery is firing), while in the final stages of processing again by using the methods of hydrometallurgical processing, that is, the process from the energy point of view is extremely inefficient;
filtering is ineffective due to the jelly-like nature of the precipitated iron hydroxide;
- low yield of extraction for both processes: pyrometallurgical (formation of forsterite) and hydrometallurgical (coprecipitation With and blocking videlectrix particles due to precipitation of Fe) processes, the total yield of Ni is approximately 75% and 50%.
One should not expect that this technology can be used to develop new projects due to the low extraction of valuable metals and the use of low-quality raw materials (preferably limonite ore), in addition, these processes require high energy costs and reagents (see Dalvi and others, 2004).
The process of acid leaching at high pressure (HPAL) (3)
In metallurgy the HPAL process is relatively simple, in the first stage using the decomposition at high temperature of more than 245°C. the Obtained suspension is neutralized with lime and decanted in a counter, then remove impurities and precipitated Ni and Co in the form of sulfide (H2S) or hydroxide (lime) or directly remove Ni and Co extraction solvent (scheme Goro). Neobyazatel the e further purification and separation include re-dissolution (if at planting get a solid substance) and cleaned using solvent extraction or selective planting. Finally, the metal is recovered by electrolysis or by reduction with hydrogen, or Nickel oxide is obtained using pyrohydrolysis (chlorides used in the form SX or IX, in contrast to the chloride process for leaching).
Features of the process:
- this method can be used for more types of ore, compared with the method of melting due to the inclusion of lemontovo method (stocks limonadovy ore twice reserves saprolite ore), but the process largely depends on the content of total sinks acid, that is, Al (clay) and, above all, Mg (<4%);
- high corrosion, especially if there are chlorides (salt in water), corrosion resistance can be improved through the use of Ti alloys of high quality, which increases the cost of the process;
- high capital investment due to the use of equipment under pressure and related construction materials;
- cost of reagents are extremely high due to the absorbers acid (Mg, Al) and the need to maintain the level of acid (due to the formation of bisulfate), as well as in connection with the necessity of neutralizing the lime (usually requires the addition of 250-400 kg/t acid, where the lower limit is specified for processing limonadovy ore with low Mg content);
- problems in the use of the implement autoclaves in connection with the formation of scale, which leads to downtime, primarily in the processing of raw materials with high content of Mg and Al.
Calculations (Dalvi and others, 2004) showed that the efficiency of the method HPAL largely depends on the quality of raw materials, that is, the estimated lower limit of quality raw materials for new projects is 1.3% Ni, excluding compensation for the expense of the average consumption of acid (see project Ambatory in Madagascar) or when using the nearest sources of cheap acid (e.g., stage of melting sulphides).
Figure 4 illustrates the inefficiency of the HPAL process with consideration of reagents used. It is established that the main reason for the consumption of acid is Mg, and to eliminate this disadvantage can only be due to the processing of ore with low Mg content (ore lemontovo type). In addition, approximately half of the cost associated with the need to compensate for the level of reagents (to compensate for the education of bisulfate at a given temperature), which in reality are not used for leaching. "More" acid is also required to add to neutralize after leaching under pressure. The higher the density of the slurry (suspension), the less the cost of reagents affect the absolute value (cost/lb Ni). However, there is a limit to the maximum density of the pulp in with the ides with constraints on viscosity.
Alternative processes using sulfates
Currently in the industry there is a tendency of the development and design of effective ways of atmospheric leaching (ALP), primarily due to decreased investment, and also for processing Simantov and saprolite. Usually limonadovy ore leached at high residual acid concentration, while saprolite ore (with a higher ability to neutralize) is then used to neutralize the residual acid and the acids formed by the hydrolysis of Fe. A combination of processes HPAL and ALP were used to develop the so-called method of acid leaching at elevated pressures (EPAL), which is currently used in the Ravensthorpe project in Western Australia. Process diagrams ALP and EPAL shown in figure 5.
The essence of the processes represented in figure 5, patented by the AM in 1970 In the way AM also firing for the partial recovery saprolite ore, that is, to improve its ability to neutralize with chastichno removing Ni. In the process described in figure 5, you can use the recirculation of any newamericanow Nickel and the balance (of which you have already removed the main number Mg) in the HPAL process (Monhemius, 1987).
Features of the process:
- at offeree leaching kinetics is characterized by low, which, however, can largely compensate for low investment, that is a relatively cheap treatment duration (compared with the process HPAL);
even if the system is atmospheric leaching is effective in the removal of Fe (in the neutralization process/hydrolysis of saprolite), still there is considerable loss of acid due to excessive leaching of Mg (however, these costs can be partially offset by the extra energy obtained in additional burning sulfur, as well as due to additional income from the sale of Nickel);
- EPAL process is characterized by large power consumption and large investments compared to the HPAL process;
- when using atmospheric sulphate process with an open system there are significant disposal problem MgSO4first of all, due to ever increasing limitations of environmental protection (primarily in the processing of ore with a high content of Mg).
In General, the process EPAL is of minimal risk, because at the stage HPAL is provided a high yield of extraction of Ni and Co, and at the same time formed remains stable Fe. Stage acid leaching has minimum requirements for neutralization and at the same time provide the indication of additional extraction of Nickel. However, the main disadvantages of this method is the high capital investment and the problem with Mg. When using acid leaching in full in sulfate environment requires extremely aggressive (strong acid) leaching conditions to ensure a high yield of extraction of Ni and Co. Such conditions, in turn, cause significant limitations to neutralize the processing saprolites material, which leads to a significant loss of sulfate due to the magnesium in solution and, possibly in the form of jarosite residue. High consumption of reagents (if there are no available sources of cheap reagents and restrictions for the protection of the environment minimises the effectiveness of the process. For this reason, have developed alternative ways to solve problems with Mg. In one such method, proposed by American Climax Inc. (previous name of the company-S), using crystallization without evaporation in an autoclave at 190-250°C for planting sulfates in the form of monohydrate. Because this process requires the use of additional and expensive autoclave was proposed process SURAL (Sulzer, Switzerland, regeneration Schultz with acid leaching), which uses the crystallization by evaporation, thus receive epsomite MgSO4·7H2O). Specified sulfate, then the evaluation is to provide thermal decomposition with the formation of SO 2(which turned into sulphuric acid plant for the production of acid and sent to the recirculation system of the HPAL process) and a neutralizing agent, magnesia (MgO), which is directed to the recirculation system process (see Monhemius, 1987). Recently patented by Skye Resources the process of atmospheric acid leaching is almost identical to the process SURAL except that the initial leaching is also atmospheric. In addition, the process of firm Skye has a less hydrated form of magnesium sulfate, i.e. after stage crystallization by evaporation is formed of magnesium sulfate with two or three molecules of water of hydration (see Hatch Feasibility Study, 2005). Processes SURAL/Skye shown in Fig.6.
Features of the process:
- replacement cost of the reagents on the cost of energy/fuel is effective or ineffective depending on the region;
- crystallization of magnesium sulfate of pure sulfate solution in the process of evaporation requires significant energy consumption (high energy consumption during the process of evaporation)that exceed the amount of energy to maintain normal water balance (which is of particular importance with increasing quality requirements for primary ore).
New proposals process using a chloride environment
Atmospheric process chloride acid is private leaching is shown in Fig.6 (a process called Jaguar, developed by the canadian company for the exploration and development of Nickel deposits, Jaguar Nickel Inc.). This process includes a stage atmospheric leaching in hydrochloric acid solution containing a high initial level MgCl2. It is assumed that the activity of the proton increases significantly by increasing the concentration of magnesium chloride in the original solution (research system HCl-MgCl2-H2O described in the article by Bates and others, (1970), and in article Jansz (1983)). The leaching can be carried out in two stages, the first stage leached Ni and Co in the solution, and the second stage control the removal of Fe. Assume that an additional advantage of hydrolysis of Fe from the salt solution is a low water activity in saline solutions, which leads to faster reaction degidrirovaniya. In principle hematite can be formed at atmospheric temperature, otherwise (pure sulfate system) requires the use of an autoclave operated at much higher temperatures. After extraction of valuable metals solution evaporated to provide the water balance and the resulting salt solution of magnesium chloride is fed into the recirculation system to the stage of leaching. The outlet from the evaporator, the liquid stream is subjected to pyrohydrolysis (see reaction 7) and receive magnesia (which casticin is directed to the recirculation system for internal neutralizing agent) and gaseous HCl. HCl is then condensed and sent to a recycling system in the reactor to atmospheric leaching.
The concept of the system for salt leaching laterite ore and the recovery of the principal amount of acid using pyrohydrolysis of magnesium chloride was first proposed by rice and Strong (Rice and Strong, 1974), who suggested the use of solvent extraction to remove FeCl3from the system, then stage annealing spray for education for sustainable hematite and for the regeneration of an equivalent amount of hydrochloric acid. Allegedly, the method includes Jaguar cost-effective approach for the treatment of iron impurities. The method is carried out at a high initial concentration of salt (solution MgCl2), which allows the hydrolysis of iron at a controlled pH at 80-105°C. However, the economic problems of the process Jaguar become apparent due to the significant amount of energy spent in the process of evaporation of excess water from the concentrated solution of magnesium chloride before pyrohydrolysis and after him, which is not comparable with the savings in regeneration of the reagents. The higher the quality of the magnesium material for leaching, the more water is consumed at the stage of pyrohydrolysis in absolute units, i.e. 1 kg of processed ore (see Fig). The process Jaguar is quickly becoming effektivnym terms of the water balance, because if you want to add an additional amount of water in the system to absorb more magnesium specified number again pariveda in the process of pyrohydrolysis. Like Jaguar "negative impact" on the water balance associated with high initial magnesium content in the ore, is observed in the process of Skye, but to a lesser extent (in this case, to prevent premature crystallization of the sulfate in the other system elements), but except that the added "extra" water will be distributed with relative efficiency in a multi-effect evaporator/crystallizer and only hydrated water from the magnesium sulfate will be affected at high temperature (expensive) stage of thermal decomposition. The lower the degree of hydration of the resulting magnesium sulfate, the lower the magnesium content in the raw material influences the rate of evaporation at high temperature stage of regeneration of the reagent (see Fig). The steeper curve (Fig), the less advanced the extracted Nickel (processing saprolite ore high quality) will increase the rate of evaporation of water during high temperature regeneration of the reagent.
Heat recovery is also an inefficient process and is complicated in reactors DL is pyrohydrolysis (Steinbach and Baerhold, 2002 and Adham and Lee, 2002). This process requires rare materials as hydrochloric acid condenses in the evaporator with heating waste heat in the heat exchange. In another embodiment, if hydrochloric acid is removed in the first stage, the observed loss of heat for regeneration. Another important factor is that some impurities, such as chlorides of calcium and sodium, are not pyrohydrolysis and the corresponding equivalent amount of chloride required to replace costly additional hydrochloric acid or magnesium chloride. It should also be noted that the overall efficiency of the reaction of pyrohydrolysis significantly below 100%.
Features of the process with a closed system and using pyrohydrolysis (process Jaguar):
- pyrohydrolysis is feasible at relatively low temperatures (~500°C), but the heat recovery difficult (high investment), which is relatively inefficient;
process Jaguar becomes uneconomical in the processing of laterite ores with high content of magnesium, that is, the specified process is intended only for processing Leonidovich ores;
impurities such as calcium and sodium, are not pyrohydrolysis, and there is a need to replace an equivalent amount of chlorides on the more expensive the hydrochloric acid or magnesium chloride.
The process Jaguar does not absorb significant amounts of magnesium and is therefore incompatible in relation to common atmospheric processes using sulfates, such as the process Skye. Recently was offered the chloride process (Myes and others, 2005), intended to exclude pyrohydrolysis, i.e. for the regeneration of hydrochloric acid by precipitation of sulfates sulfuric acid (chemical reaction presented on Fig.9). The principle of this process is to use chemical precipitation crystallization cheap sulfuric acid for the regeneration of expensive hydrochloric acid unlike pyrohydrolysis. In the process Intec use the transformation CaCl2/SO4. The principle of this process is similar to the process Jaguar, but except that of the liquid outlet stream to remove iron and removing the Ni/Co is carried out in the presence of lime. Then from the resulting solution precipitated magnesium in the presence of lime with the formation of magnesia (MgO). During all three operations mainly replacing chloride cation equivalent amount of calcium chloride. The total amount of hydrochloric acid consumed in the system, regenerate adding sulfuric acid, which leads to the precipitation of calcium sulfate (nor the coy solubility). The regenerated hydrochloric acid is returned via the recirculation system to the atmospheric leaching process. Sulphuric acid and lime, in turn, can be regenerated at the stage of thermal decomposition of calcium sulfate. However, a simple thermodynamic model of the reaction of thermal decomposition (using the process HSC) reveals some difficulties (see figure 10).
Although the concept of regeneration of sulphuric acid and lime is of interest for thermal decomposition of sulfates requires high temperatures, and thus require the consumption of large amounts of energy. Thus, the formation of extremely refractory directionspanel type of lime. In addition, in the process of thermal decomposition of the formed intermediate the solid phase, which presents additional problems.
Features of the process with a closed system and using precipitation of calcium sulfate in sulfuric acid for the regeneration of hydrochloric acid) (Intec process):
in this process get implemented (trademark) by-products of bassanite (CaSO4·1/2H2O) and magnesia (MgO), however, difficulties arise when cleaning by-products of this type;
- unlikely is the possibility of cost-effective regeneration of sulphuric acid and lime is Ecodom thermal decomposition of calcium sulfate, the reaction of thermal decomposition occurs through the formation of intermediate products, the product of lime is refractory, and the process requires large amounts of energy;
- the higher the magnesium content in the ore raw materials, the greater the required sulphuric acid and lime, which leads to lower efficiency in the processing of saprolite ore.
Thus, there is a need for a more efficient economy leaching process for recovery of valuable metals. First of all, there is a need in the way of accumulation or regeneration of hydrochloric acid in chloride salt leach solution, it is required to eliminate the need for evaporation of large quantities of water, which is required when using pyrohydrolysis. All used additional reagents should be inexpensive, and it should be possible regeneration of the main reagents used in the process.
Summary of the invention
In the first embodiment, the present invention proposes a method of leaching of valuable metals from ores containing the specified precious metal, comprising the following stages:
leaching of the ore in the presence of hydrochloric acid with the formation of metal chloride in the leach solution,
d is the addition of sulfuric acid in the leach solution,
removing the metal sulfate from the leach solution and
simultaneous regeneration of hydrochloric acid.
Metal sulfate is characterized by the formula MeSO4·yH2O, where
Me denotes a metal, and
y is 0 or more, for example from 0 to 3, more preferably 0 or 1.
The source of the metal in the metal sulfate is preferably ore.
The ore is preferably an oxide or silicate metal-containing ore, such as zinc oxide ore.
Ore can also be lateritic Nickel ore, such as sapralieva or Limonova ore.
In another embodiment, the ore is a sulfide, titanium, or aluminum ore.
Metal sulfate are planted from the leach solution or extracted from the leach solution by crystallization in the process of evaporation.
The precious metal is chosen from the group comprising Zn, Cu, Ti, Al, Cr, Ni, Co, Mn, Fe, Pb, Na, K, CA, platinum group metals and gold.
The metal composition of the metal sulfate may be valuable metal, and the method additionally includes the stage of decomposition of the metal sulfate to extract the precious metal.
In another embodiment, the metal composition of the metal sulfate is less valuable metal in contrast to precious metal, such as magnesium.
Metal sulfate can be treated under conditions which produce sulfur dioxide,sulfur trioxide or a mixture.
Precious metal can be extracted regardless of the metal salt formed by the addition of sulphuric acid.
The regenerated hydrochloric acid can be a super-azeotropic acid.
As a solution of metal chloride can be used with a salt solution of an alkali metal and/or in the same way as a sulfate of the metal sulfate is used of the alkali metal.
The regenerated hydrochloric acid may further be directed to a recirculation system in the leaching process. Hydrochloric acid is used to leach the ore, used in the composition of the salt solution, for example, from approximately 10% to approximately 90% saturated solution of magnesium chloride, from about 10% to about 90% saturated solution of zinc chloride or from about 10% to about 90% saturated solution of chloride of another metal. More preferably as a salt solution to use from about 25% to about 40% saturated solution of magnesium chloride, from about 25% to about 40% saturated solution of zinc chloride or from about 25% to about 40% saturated solution of chloride of another metal. Even more preferably as a salt solution to use about 30%saturated solution of magnesium chloride, approximately 30% saturated solution of zinc chloride or approximately 30% saturated solution of chloride of another metal.
Metal sulfate can be used to obtain a metal oxide. For example, metal sulfate is subjected to thermal decomposition with the formation of a metal oxide and sulfur dioxide, sulfur trioxide, or mixtures thereof. The metal oxide is chosen from the group comprising magnesium oxide, zinc oxide, iron oxide and aluminum oxide. Sulfur dioxide, sulfur trioxide, or their mixture can be used to obtain sulfuric acid, which in turn are returned to the leaching process for the regeneration of hydrochloric acid.
Valuable metal is leached from the ore at a temperature of from about room temperature to about the boiling point of a solution of metal chloride to leach.
One or more precious metals, such as cobalt, Nickel, platinum group metals, gold, silver and/or copper, can be selectively highlight of the solution prior to the formation of metal sulfate.
Impurities of iron and/or other residual impurities formed after solubilization of ore removed from the ore, for example, by solvent extraction with subsequent pyrohydrolysis or hydrolysis.
The concentration of sulfuric acid is at least 30%, for example approximately 98%.
In the second variant implementation is tvline the present invention proposes a method of leaching precious metal from the ore, containing the specified precious metal, comprising the following stages:
leaching of the ore in the presence of hydrochloric acid with the formation of soluble in the leach solution of metal chloride,
adding sulfur dioxide in the leach solution,
removing the metal sulfate or sulfite of metal from the ore and
simultaneous regeneration of hydrochloric acid.
Metal sulfate or sulfite metal is characterized by the formula MeSOx·yH2O, where Me denotes a metal, x is 3 or 4, and y is 0 or more, for example from 0 to 3, preferably 0 or 1.
The source of the metal in the metal sulfate or sulfite metal is preferably iron ore.
The method also includes a step of adding an oxidant in the leach solution for oxidation of bivalent iron ions to ferric ions.
As ore is used mainly oxidic or silicate ore containing metal, such as zinc oxide ore.
As ore use of lateritic Nickel ore, such as cyprotel or limonite.
In another embodiment, as ore use sulfide, titanium, or aluminum ore.
Metal sulfate or sulfite metal precipitated from the leach solution or recovered from the leach solution by crystallization at at the Ariani.
Precious metals chosen from the group comprising Zn, Cu, Ti, Al, Cr, Ni, Co, Mn, Fe, Pb, Na, K, CA, platinum group metals and gold.
In a way, you can use catalyst to accelerate the reaction. Suitable catalysts are copper in solution, graphite or charcoal.
As the metal in the metal sulfate or sulfite metal presents valuable metal, and the method additionally includes the stage of decomposition of the metal sulfate or sulfite metal for recovery of valuable metal.
As the metal in the metal sulfate or sulfite metal may be less valuable metal, such as magnesium.
Metal sulfate or sulfite metal handle in the conditions in which the formed sulfur dioxide, sulfur trioxide or a mixture.
Precious metal can be extracted regardless of the metal salt formed by the addition of sulfur dioxide.
The regenerated hydrochloric acid can be super-azeotropic acid.
Magnesium can be extracted from the leach solution prior to the addition of sulfur dioxide and replaced by various metal ions, such as calcium or lead. After removal of magnesium and adding sulfur dioxide is formed salt of the metal, for example an intermediate sulfite or sulfate. Intermediate sulfite or sulfate may be calcium sulfate, calcium sulfite, sulfate of lead or self is tons of lead.
As a solution of metal chloride can be used alkaline solution.
As a metal sulfate or sulfite of metal may be used the alkali metal sulfate or sulfite of an alkali metal.
The regenerated hydrochloric acid may be directed to the recirculation system in the leaching process.
Hydrochloric acid used for leaching, may enter into the composition of the salt solution, for example, from approximately 10% to approximately 90% saturated solution of magnesium chloride, from about 10% to about 90% saturated solution of zinc chloride or from about 10% to about 90% saturated solution of chloride of another metal. More preferably as a salt solution is used from approximately 25% to approximately 40% saturated solution of magnesium chloride, from about 25% to about 40% saturated solution of zinc chloride or from about 25% to about 40% saturated solution of chloride of another metal. Even more preferably as a salt solution is used by about 30% saturated solution of magnesium chloride, about 30% saturated solution of zinc chloride or approximately 30% saturated solution of chloride of another metal.
Metal sulfate or sulfite is atalla can be used to obtain a metal oxide. For example, metal sulfate or sulfite metal is subjected to thermal decomposition with the formation of a metal oxide and sulfur dioxide. The metal oxide is chosen from the group comprising magnesium oxide, zinc oxide, iron oxide or aluminum oxide. Sulfur dioxide can be used to obtain sulfuric acid, which in turn can be used in the leaching process for the regeneration of hydrochloric acid.
Intermediate sulfate or sulfite may be subjected to thermal decomposition with the formation of a metal oxide such as calcium oxide, and sulfur dioxide, sulfur trioxide, or mixtures thereof. Sulfur dioxide, sulfur trioxide or a mixture can be reused for vysalivaniya sulfates or sulfites from the leach solution and regeneration of hydrochloric acid.
Valuable metal is leached from the ore at a temperature of from about room temperature to about the boiling point of a solution of metal chloride to leach.
One or more precious metals, such as cobalt, Nickel, platinum group metals, gold, silver and/or copper is selectively removed from the solution before the formation of metal sulfate or sulfite of metal.
Impurities of iron and/or other impurities generated after solubilization of the ore, can be partially or completely removed from solution of DL is leaching, for example, by solvent extraction with subsequent pyrohydrolysis or hydrolysis.
The concentration of sulfuric acid may be at least 30%, for example approximately 98%.
Brief description of figures
Below the invention is described in more detail with reference to the accompanying drawings on which is shown:
figure 1 - schematic diagram of the processing saprolite method of melting;
figure 2 - schematic diagram of the preferred processing limonite using Caron;
figure 3 - schematic diagram of the processing of limonite (smectite) using the HPAL process;
figure 4 - energy consumption and running costs for the operation of the HPAL process;
5 is a schematic processes of atmospheric leaching (ALP) and HPAL-ALP (EPAL);
6 is a principle processes Sural/Skye: crystallization of magnesium sulfate and regeneration of the initial reagents;
7 - principle process Jaguar: primary regeneration reagents using pyrohydrolysis of magnesium chloride;
Fig - comparison of (hypothetical) number one stripped off water in the process of pyrohydrolysis solution of magnesium chloride and in the process of thermal decomposition of crystalline magnesium sulfate;
Fig.9 - the principle of the Intec process: primary regeneration reagents using precipitation of calcium sulfate;
figure 10 - thermal decomposition of calcium sulphate, see m the del process HSC;
11 - the principle of the method according to the present invention: regeneration reagents using deposition and thermal decomposition of magnesium sulfate;
Fig - solubility of magnesium sulfate depending on the change in the quantity of magnesium chloride (see model AspenPlus);
pig activity of hydrogen ions in a solution of 0.5 mol/kg HCl depending on the concentration of magnesium chloride and temperature;
Fig - moralnosti hydrogen ions in solutions: from 0 to 1 mol/kg of HCl and 2.5 mol/kg MgCl2and from 0 to 0.5 mol/kg H2SO4and 2.5 mol/kg MgSO4accordingly, depending on temperature;
Fig - thermal decomposition of magnesium sulfate, see model HSC;
Fig - crystals of magnesium sulfate is precipitated from the salt solution at different temperatures;
Fig - schematic diagram of the method according to the invention;
Fig diagram 1 of the method according to the invention;
Fig diagram 2 of the method according to the invention;
Fig extraction of Nickel from saprolitic samples;
Fig extraction of cobalt from saprolitic samples;
Fig profiles extraction of all metals from saprolite using a salt solution of high concentration;
Fig extraction of Nickel from Leonidovich samples;
Fig extraction of cobalt from Leonidovich samples;
Fig profiles extraction of all metals from limonite using salt R is the target of a high concentration;
Fig extraction of Nickel from silicate-Klimontovich samples;
Fig extraction of cobalt from silicate-Klimontovich samples;
Fig profiles extraction of all metals from the silicate limonite using a salt solution of high concentration;
Fig - effect of MgCl2on the extraction of Nickel;
Fig - photograph of typical crystals (scanning electron microscope);
Fig reactor with oil heating, inset depicts a syringe to add reagents;
Fig - method for processing sulfide ore;
Fig - chloride and sulfate closed loops in the integrated process of processing sulphide ores;
Fig - laboratory installation for non-oxidizing atmospheric leaching;
Fig - kinetics of leaching in non-oxidizing conditions in the presence of HCl at 90°C (+38-75 μm);
Fig - x-ray analysis (powder reginorum) of crystalline product.
Detailed description of embodiments of the present invention
The method according to the present invention presents a new General approach to the optimization of reagents and energy. The source reagent, i.e. HCl, regenerate, this eliminates the need to neutralize the solution before crystallization, obtained after leaching, or need to add in the fresh R the agents. The effectiveness of this approach increases with the use of concentrated salt solutions, which provides additional advantages: 1) education digidratirovannogo crystalline product, i.e. the reduction of energy consumption by thermal decomposition (regeneration reagents), 2) education digidrirovanny stable products of the hydrolysis of Fe (such as hematite) at ambient temperature, 3) fast kinetics of leaching due to high activity of protons and 4) leaching and extraction of important by-products (e.g., Pb, Ag).
The method according to the present invention is intended for leaching one or more precious metals in a solution containing hydrochloric acid, from which the precious metal is extracted (recovered) in the form of solid sulfate or sulfite with simultaneous regeneration of hydrochloric acid in solution.
Valuable metal is leached from the metal-containing material, which is a sulfide or resolvedname material. For example, the material can be a metal oxide ore, such as zinc oxide ore, laterite Nickel ore, such as sapralieva or Limonova ore, the sulfide ore, aluminum ore and titanium ore. First, the precious metal forms a soluble chloride of the metal, then obrazets the solid sulfate or sulfite.
Precious metals are preferably chosen from the group comprising Zn, Cu, Ti, Al, Cr, Ni, Co, Mn, Fe, Pb, Na, K, CA, platinum group metals and gold.
The solution of metal chloride may be an alkaline solution, and/or metal sulfate is the sulfate of an alkali metal.
Sulfuric acid is usually at a concentration of at least 30% (e.g., approximately 98%) or sulfur dioxide is added to the solution containing the leached precious metal, you get a solid sulfate or sulfite of metal, which is then removed. In this case, for the regeneration of an expensive reagent (hydrochloric acid) use relatively inexpensive reagent (sulphuric acid or sulphur dioxide), which leads to significant savings.
Solid metal sulfate or solid metal sulfite is usually characterized by the formula:
where Me denotes a metal,
x is 3 or 4, and
y is 0 or more, for example from 0 to 3 and more preferably 0 or 1.
A solution containing hydrochloric acid, usually a saline solution (i.e. chloride solution), such as from about 10% to about 90% saturated solution of magnesium chloride, from about 10% to about 90% saturated solution of zinc chloride or from about 10% to about 90% saturated solution of chloride drugog the metal. More preferably as a salt solution using approximately 25% to approximately 40% saturated solution of magnesium chloride, from about 25% to about 40% saturated solution of zinc chloride or from about 25% to about 40% saturated solution of chloride of another metal. Even more preferably as a salt solution using 30% saturated solution of magnesium chloride, 30% saturated solution of zinc chloride or a solution of chloride of another metal or alkali metal. The content of metal or alkaline metal salt solution is usually chosen depending on the sinks acid present in the leach solution and their concentrations in most cases chosen in such a way as to ensure a significant difference in the solubility of chlorides and sulphates.
The metal forming the cation chloride and which is a main component of the saline environment (leaching), preferably chosen from the major cations, absorbing acid and present in the ore intended for leaching.
The concentration of metal chloride is usually chosen to meet the following goals:
a positive effect on the leaching process, as described, for example, to process Jaguar,
ensure leaching of metal from the ru is s, not exceeding the solubility of metal chloride in the conditions of leaching (in another embodiment, water is added to avoid the loss of chloride in the solid phase),
accelerating the deposition of the corresponding sulfate or sulfite - i.e. the concentration of the metal is excessive in relation to the solubility of the sulfate or sulfite,
impact on the degree of hydration phase precipitate sulfate or sulfite to the degree of hydration of the salts obtained was lower compared to the possible degree of hydration of the salts obtained from the neutral solution of the sulfate or sulfite, and
not to exceed the limits of solubility required at other stages of the process. In this case require different operating temperatures at various stages of the process (in another embodiment, in order not to exceed the limits of solubility, at certain stages of the process, water is added).
The initial concentration of hydrochloric acid is chosen in such a way as to ensure a high degree of leaching of the metal and at the same time to comply with the absorption of acid ore. Found that leaching at the final pH of 0.5 or less leads to increase metal recovery to the value of over 80%. However, this value depends on the nature of the ore, and specialists in the art it is obvious that will satisfy the optimum degree of leaching can be ensured when using other materials with large values of ultimate pH, unlike investigated in the present invention.
Sulfuric acid or sulfur dioxide is usually added to the solution in sufficient quantity to power regenerated hydrochloric acid was higher than the azeotrope concentration, which is determined by the solubility of metal chloride or alkali metal chloride, in comparison with the strength of hydrochloric acid, which is formed after deposition in the form of sulfate or sulfite. Saline solution is characterized by a low initial concentration, which is combined with an additional concentration of metal chloride in the course of the leaching process. Preferably the amount of added sulfuric acid or sulfur dioxide in the above solution should slightly exceed the quantity required to compensate for the concentration of the acid-salt solution to the initial value. In other words, the initial low concentration of metal chloride should not be lowered in the process of crystallization of the corresponding sulfate or sulfite. In another embodiment, the solution after leaching into fractions and only one of them is used for the deposition of sulfate or sulfite, while deposition occurs depending on the solubility, while the initial level of chloride does not change in the remaining untreated fractions.
The process also includes article is Dios crystallization to obtain crystals of the metal sulfate or sulfite of metal with low content of water of hydration. In another embodiment, to reduce the cost of these reagents for the purpose of such chemical is crystallized using the crystallization by evaporation (within or with a small excess of standard water balance). This option is possible due to the simultaneous influence of the initial concentration of salt in the solution on the degree of deposition of salts in the process of evaporation of water. Moreover, the joint deposition of Ni within the crystalline structure of magnesium salts usually prevails during crystallization at low temperatures. The tendency of Ni in co-crystallization is significantly reduced when the chemical crystallization at a temperature close to the boiling temperature of the solution at atmospheric pressure.
Such salts are used as commercial products, are subjected to thermal decomposition with the formation of a metal oxide, which is also used as a commercial product, as well as sulfur dioxide, sulfur trioxide, or mixtures thereof, and/or their re-dissolved in the solution of sulfate and then subjected to electrolysis.
One or more precious metals, such as cobalt, Nickel, platinum group metals, gold, silver and/or copper is selectively removed from the solution before the stage of formation of sulfate or sulfite of metal.
Iron and/or other residual impurities, obrazuyuschie is in the solubilization of ore, partially or completely removed from the leach solution, for example, using solvent extraction with subsequent pyrohydrolysis or hydrolysis.
The metal composition of the sulfate or sulfite metal can be a valuable metal, and the method includes the stage of decomposition of the metal sulfate to extract the precious metal.
In another embodiment, the metal composition of the sulfate or sulfite metal is less valuable, such as magnesium, and the precious metal is extracted independently of the metal salt formed by the addition of sulfuric acid or sulfur dioxide.
The sulfate or sulfite of metal may be treated to release sulfur dioxide.
The method is not necessarily limited temperature intervals, provided that the solubility of the metal sulfate or sulfite metal is much lower than the solubility of the corresponding chloride. However, the leaching mainly carried out at a temperature from room temperature to the boiling point of the solution, and the stage of crystallization of the sulfate or sulfite is usually carried out at a temperature at which the difference in solubility as possible.
Before adding sulfur dioxide magnesium is not necessarily removed from the leach solution and replace with the other metal cation, such as calcium, lead or barium. After removal of the magnesium salt of the metal forming the I adding sulfur dioxide, an intermediate sulfite or sulfate such as calcium sulfate, calcium sulfite, sulfate of lead, lead sulfite, barium sulfate or barium sulfite. Intermediate sulfate or sulfite is subjected to thermal decomposition, with the formation of a metal oxide such as calcium oxide, and sulfur dioxide. Sulfur dioxide is used again to vysalivaniya sulfate or sulfite from the leach solution and regeneration of hydrochloric acid.
Private embodiments of the present invention may have the following features:
the concentration of hydrochloric acid is compensated in a salt solution of chloride of non-ferrous metal,
the leaching process is carried out in chloride environment adding gaseous sulfur dioxide or sulfuric acid,
metal, such as zinc or magnesium, is extracted from salt chloride solution in the form of a salt with a small amount of hydration water, which is subjected to thermal decomposition, re-dissolve in the sulfate solution and electrolysis directly from the resulting solution, or in the form of commercial products, in the form of sulfate or sulfite, or after thermal decomposition to oxide.
The present invention will be described in detail below in the form of several non-limiting examples.
In the first variant of the implementation of the present invention proposes a method of leaching of magnesium, and at least a certain amount of valuable Nickel and cobalt from bisulfide ores, such as laterite ore, limonite, oxide ore and/or silicate saprolite, in the original environment of hydrochloric acid. The basic leaching agent is the hydronium ion formed in the presence of chlorides, the presence of which is associated with the presence of its impurities, primarily of magnesium chloride.
Processing bisulfide materials are described in detail below on the example of Nickel laterite ores. Specialists in the art it will be obvious that the same method can be used to process other bisulfide materials, such as silicates of zinc, bauxite, etc. Used laterite is also an example in which the precious metal is not metal, used for phase compensation of the concentration of chloride salt solution. Schematic diagram of the process shown in Fig.
Regeneration of hydrochloric acid and extraction of magnesium, as described above, is not associated with the excessive removal of water by evaporation, because first remove the magnesium in the deposition, instead of the electrolyte solution of magnesium chloride (as in method Jaguar). However, in another embodiment, the crystallization in the process of evaporation (within or with a small excess of standard water balance) you can use the VAT to reduce the cost of reagents at the stage of chemical crystallization. This option is possible due to the simultaneous effect of the initial concentration of the salt solution on the degree of deposition of salts in the process of evaporation of water.
The concentration of the acid salt solution of magnesium chloride after leaching compensate by adding sulfuric acid or gaseous sulfur dioxide, resulting precipitated sulphate or sulphite magnesium with a low degree of hydration and is formed in the solution of hydrochloric acid.
The residue after leaching of laterite process at the next stage of leaching, in order to maximize the output of Nickel and cobalt.
In the case of sulfate experimental data Linke and Seidell (1965) suggests that keseric (monohydrate magnesium sulfate) is the preferred product of crystallization at a high temperature (approximately 100°C), which allows to reduce to the minimum energy required for ignition with the formation of magnesia (magnesium oxide, which is partially directed to recirulation system as a neutralizing agent) and sulfur dioxide. A simplified reaction scheme is shown below:
In this way we obtain a crystalline product with a total chloride content less than 0.01%. It is established that the co-crystallization of Ni in the crystal structure of kieserite reduced to the minimum is at carrying out the specified reaction at a temperature close to the boiling temperature of the solution (or at elevated temperature and pressure). It is assumed that using this method you can get magnesium oxide with high purity, which can be used as a commercial product and/or as a neutralizing agent. In another embodiment, if the loss of Nickel are invalid, the Nickel is removed before crystallization using chemical methods, for example, ion exchange, solvent extraction, diffusion saturation (cementing), deposition, etc. in Addition, relatively expensive regenerate hydrochloric acid using sulfuric acid or sulfur dioxide, which are relatively cheap and readily available reagents.
A pair of Fe3+/Fe2+in the salt system plays an extremely important role in the direct use of sulfur dioxide to precipitate the sulfate or sulfite. In the absence of ferric ion, the ability of a solution to absorb sulfur dioxide is extremely small in solutions with high initial salt concentration, i.e. the absorption in this system ineffective. However, in the presence of ferric ions is direct absorption of gas in solution due to the reduction reaction of trivalent iron to divalent. Indicated the reaction is accompanied by changes in the solution, which, in turn, lead to preferred salting out of the sulphate or sulphite magnesium.
The method according to the present invention, is described in this context, shown at 11 and is based on the low solubility of magnesium sulfate in solution in the presence of large quantities of magnesium chloride in the original solution. Adding sulfuric acid in a saturated leach solution (PLS) leads to the precipitation of sulfate with the simultaneous regeneration of hydrochloric acid, which is returned to the recirculation system for reuse at the stage of leaching at atmospheric conditions. On Fig shows the estimated change in the solubility of magnesium sulfate with increasing initial content of chloride when using commercial software AspenPlus intended for modeling processes.
Precipitated magnesium sulfate in turn undergoes thermal decomposition with the formation of magnesia (magnesium oxide) for use as a neutralizing agent) and gaseous sulfur dioxide. Gaseous sulfur dioxide is transformed into sulfuric acid at the facility for the regeneration of acid and re-use on stage chemical precipitation of sulfate.
In addition to changes in temperature and water content, an important parameter in the process is to focus with the left solution. Conversely, in the process using a sulfate, such as the process Skye, degrees of freedom are only the temperature and water content. In this case, it is necessary to add large quantities of water to prevent crystallization in the stream, and, therefore, there is a need for removal of large quantities of water (kg processed ore) to achieve the required level of crystallization by evaporation. The importance of such a "negative" effect of water increases significantly with increasing magnesium content in the ore. On the contrary, in the present invention is proposed stage chemical crystallization, and not the process of evaporation, thus, the water balance does not depend on the content of magnesium in the ore raw materials. In addition, due to the high initial concentration of salt in the method according to the present invention occurs simultaneous effect in the process of evaporation, which is simply based on the water balance, which leads to the deposition of larger amounts of magnesium sulfate. This effect compensates for the inefficiency of chemical vapor deposition (due to undesirable solubility), without the need to significantly increase energy costs of steam. Thus, the system based on the mixed chloride-sulphate electrolyte increases the versatility of the process sravnenie the simple process with a closed system using sulfate (see the way Skye).
In this case, suppress the solubility of sulfate in the system while maintaining a high initial concentration of chloride in the system. At the same time, a high initial concentration of chloride leads to high activity of protons and low water activity. On Fig shows a three-dimensional graph of the activity of protons from the temperature and concentration of magnesium chloride.
This model was designed specifically to evaluate the activity of individual ions N+in an electrolytic system HCl-MgCl2-H2O. On Fig shown that the activity of individual ion N+(which is an important parameter, although not the only determining the rate of destruction of laterite to extract Ni) increases when adding the original salts such as MgCl2. At 65°C and in the presence of 1M HCl observed a tenfold increase in such activity. Unfortunately, the observed effect is significantly reduced when the temperature increases. Therefore, there are two opposite effects: to ensure high activity of N+leaching should be carried out at low temperature, and, on the other hand, with the aim to exceed the barrier of activation energy at the interface solid/liquid leaching should be carried out at elevated temperature. However, pixelation what I for example, at 85°C the activity of N+increased almost twice compared to the activity in the clean system HCl-H2O. This fact is of particular interest because it is similar to the "aggressiveness" of protons is not implemented in pure sulfate system.
On Fig shown that when comparing the two systems in an electrolytic system hydrochloric acid/magnesium chloride there is a much higher concentration of protons compared to an equivalent concentration of sulfuric acid in the system magnesium/sulfate. The main cause of the observed effect is the specificity of various ions in the electrolyte: connection N+-Cl-is weak, while the relationship of N+-SO42-is strong and "captures" most of the protons with the formation of bisulfate complex, HSO4-. The tendency to form bisulfate ion leads to the relative weakness of sulfuric acid, particularly at high concentrations of magnesium sulfate and high temperature.
The method according to the present invention is primarily intended for processing in the presence of impurities such as sodium and calcium, in contrast to the pure chloride method, such as method Jaguar. In the system of the present invention should be sufficient sulfate to education arose the sodium, from which the regenerated magnesium chloride according to the following scheme:
Indeed, preferred is the presence of a sufficient amount of sulfate in the conditions of the above reaction to replace the entire quantity of consumed chloride in the system. Optionally, the system adds a small amount of sodium chloride to circulate a sufficient number of sodium ions at the stage of iron removal. A small amount of calcium chloride in the solution is deposited with the formation of insoluble calcium sulfate in sulfuric acid at the stage of chemical crystallization. Despite the fact that the calcium sulphate is not decomposed simultaneously with magnesium sulfate, the difference can be compensated by burning an equivalent amount of elemental sulfur. Thus, in addition to the efficient processing of major impurities in the system, loss of chloride and sulfate are compensated by adding cheap reagents, such as sodium chloride and elemental sulfur, respectively. In respect of other manganese impurities can be easily removed in the presence of excessive amounts of SO2(for oxidation in the presence of SO2/O2to MnO2) without the need for special cost of its removal. From the point of view of environmental protection and economic point of view, VA is tion is the lack of a liquid drainage flows.
By calcination of precipitated magnesium product for the decomposition of the ideal product in the reactor with a fluidized bed (900-1200°C) requires 1.5 to 4 mol of water per 1 mol of magnesium. This technique is described in patent US 4096235, which fully included in the present description by reference. Partial rehydration monohydrate (to obtain a product with an optimal degree of hydration for thermal decomposition) is achieved by controlling the time of contact of the crystalline product deposition with a suitable aqueous medium. The method of regeneration of sulfuric acid from sulfur dioxide formed during combustion of sulfate/sulfite is known and allows reuse of sulfuric acid, if it is justified from an economic point of view.
The main advantage of using sulfate/sulfite for the decomposition of magnesium to magnesium oxide is that it requires much less energy (compared to pyrohydrolysis solution of magnesium chloride as described in method Jaguar) in connection with the removal of water, i.e. the water of hydration. Thus obtained magnesium oxide of high quality for use as a commercial product.
Thermal decomposition of magnesium sulfate is a relatively straightforward process. On Fig shows the chemical model HSC to mention the definition of decomposition in the presence of carbon as a reducing agent. Kinetics of thermal decomposition even at 800°C is very fast, because of the precipitated magnesium sulfate forms extremely fine dispersed particles (<10 μm). On Fig shown that the deposition at low temperature (65°C) leads to the formation of acicular particles of uranyl and extremely fine dispersed particles monohydrate. Precipitation from salt solutions at higher temperatures (110°C) leads to the formation of a monohydrate, i.e. kieserite (MgSO4·H2O). Thus, we can assume that the energy of thermal decomposition in the method according to the invention lower the energy by way of Skye, in which at least 2 molecules of water of hydration present in the precipitated salt. Any amount of magnesium chloride is associated with small particles, is subjected to pyrohydrolysis with the formation of gaseous HCl, which can be used in the recirculation system. A typical composition of the precipitated sulfate (from experimental data) includes: 17,1% Mg, <0,05% Fe, 0.1% of Ni, <0,05% Co, 2% Cl, taking into account the balance of sulfates and water. The Nickel content in the precipitated salt is dependent on temperature: its content increases with decreasing crystallization temperature.
Use cheaper sources of fuel such as heavy fuel oil (HFO) and, above all, the coal is of low quality. Any number of sulfur in with what tave coal is oxidized with the formation of SO 2and, therefore, reduces the cost of adding additional reagents that contain sulfur.
As mentioned above, the main advantage when operating chloride systems is a tendency to de-hydration of the solid phase in equilibrium with a salt solution. In addition to education kieserite (monohydrate), or even the anhydrous salt by crystallization, when the hydrolysis of iron in atmospheric conditions is formed hematite. It is the preferred product of hydrolysis not only from the point of view of environmental protection, but also by the improved characteristics of sedimentation and filtration in comparison with more gel or hydrated sediments, resulting in net sulfate system. The observed phenomenon leads to the formation of a solid cake with a lower moisture content and, consequently, to reduce losses of valuable reagents in the system.
Another important factor is the tendency of Nickel and cobalt together absorbed in the crystal structure of iron hydroxide (III) and goethite, while (similar to natural processes) hematite almost unable jointly to absorb these compounds. The preferred precipitation of hematite from the salt solution, primarily achieved by controlled deposition under conditions of excess of NASA is possible when adding a seed for crystallization of hematite in the hydrolysis of iron (see article Riveros and Dutrizac, 1997).
Schematic diagram of the process shown in Fig. The use of a recirculation system in the reactor at atmospheric pressure allows to increase the time of contact of hydrochloric acid and to minimize the cost of reagents for neutralization (internal recirculation loading of magnesium per 1 unit of mass of the processed ore) in the system. Neutralize only the outlet stream for the hydrolysis of iron and then to extract the Nickel and cobalt in the deposition process of hydrolysis. After stage neutralization using one-stage evaporation to compensate for the water balance. When chemical crystallization in a split stream of the main recirculation system of the regeneration of the equivalent amount of hydrochloric acid + loss from the system. The precipitated sulfate is calcined with the formation of gaseous SO2and magnesium oxide. Gaseous SO2turn into sulfuric acid in a plant for producing sulfuric acid and return to the mould while part of magnesium oxide is directed to the recirculation system for internal neutralization. The excess of the obtained magnesium oxide is used as a commercial product.
An important feature of the present invention is relative regardless of the diamonds from the magnesium content in the ore raw materials, as shown in Fig. If there is a cake monohydrate at the stage of regeneration (thermal decomposition of magnesium sulfate), require only a small evaporation or exclude it altogether from the system, which allows you to handle saprolite ore of high quality and is a considerable advantage in respect of current expenditure in absolute terms due to the high cost of Nickel.
Below is a list of all the necessary criteria, which satisfies the method according to the present invention.
The basic performance criteria
The decrease in capital investment compared with HPAL processes and melting Smelting:
- when operating the hydrometallurgical plant does not require high pressure, and the operation pyrometallurgical facilities are only average temperature
despite the fact that, when using a chloride environment requires special corrosion-resistant materials, all stages is carried out in atmospheric conditions.
The reduction of energy consumption compared with Smelting process:
- when adding a reducing agent in the system thermal decomposition digidratirovannogo of magnesium sulfate (or containing a small amount of hydrated water) is achieved at temperatures less than 800°C,
- the amount of energy waste on the stage of decomposition at high temperatures is spent on heating in hydrometallurgical system using an evaporator in the secondary energy
- use of sulfur-containing low-quality coal as the reductant and fuel for direct combustion in a furnace for thermal decomposition.
Reducing the cost of reagents compared to the HPAL process:
when thermal decomposition of magnesium sulfate is the regeneration of sulfate (for sulfuric acid) and a neutralizing agent (magnesium oxide),
- adding additional sulfur is limited to standard losses of the closed system, which is compensated by burning additional quantities of sulfur (inexpensive reagent),
- add additional chloride losses are limited to the standard of the closed system, which can be compensated by adding inexpensive chloride such as sodium chloride,
impurities, such as sodium and calcium, are removed at the stage of removal of sulphate (jarosite sodium and calcium sulphate, respectively), i.e. does not require the use of drainage flows.
The output of the extraction of Nickel and cobalt is comparable with the HPAL process:
higher activity of protons and, therefore, more aggressive system for leaching (in comparison with the processing of ore at atmospheric pressure in a pure sulfate),
despite the fact that the kinetics of the process is slower compared to the HPAL process, this is Dostatok compensated for by increasing the size of the reactors for leaching under atmospheric conditions, i.e. the time of contact of the reactants becomes relatively cheap.
The separation of the liquid/solid phase and the stability of the rest:
- the products of hydrolysis of iron precipitated in the presence of chlorides, are characterized by improved properties by sedimentation and filtration.
in the chloride system at atmospheric high pressure are formed digidrirovannye products of the hydrolysis of iron, such as hematite (sustainable environments),
- magnesium sulfate decomposes at an elevated temperature that satisfies the requirements of the acid and neutralizing agent in the internal system,
- use a closed system, i.e. no discharge flows into the environment.
Uvelichenie income from the sale of Nickel, obtained from a variety of different types of ore:
- independence from magnesium content allows you to handle at the same time limonite and saprolite ore, which increases the income from the sale.
Two principal schemes, designed with balance of mass/energy, shown in Fig and 19. On Fig presents the General scheme 1. The original salt of the present invention is used to reduce the solubility of magnesium sulfate. Crystallization in the process of evaporation, without exceeding normal water balance used to reduce costs in the process of chemical deposition, i.e. to compensate for the inefficiency of the stages of chemical solidification due to the formation of bisulfate. In the diagram on Fig shown that it is possible to effectively eliminate the need for evaporation of water, depending on changes in the content of magnesium in the ore raw materials. On Fig shows another variant of the scheme, taking into account the inefficiency of chemical crystallization in an environment with a high content of acid due to the formation of bisulfate. This diagram shows the worst case scenario from the point of view of regeneration of the reactants.
1. Dynamic characteristic minerals
Samples of laterite ore was tested for dynamic stability. Selected 3 ore sample for further testing of the effect of salt solution with a high initial concentration of salt and sulfur dioxide. The tests were carried out at high concentrations of solids (30%) and acid (sulfuric acid concentration is 2018 kg/t, hydrochloric - 1500 kg/t, in both cases 41,2 kg N+/t).
For tests used saprolite, iron and silicate ore Jacaré (Brazil). The original composition of the components in the samples shown in table 1.
|The original composition of the components used in sample|
|Iron ore Jacaré||1,14%||0,17%||42,23%||0,63%||1,25%||10,00%||2,38%||0,85%|
|Silicate ore Jacaré||1,25%||0,22%||are 22.42%||2,35%||2,30%||20,92%||1,09%||0,92%|
Each sample was tested in the following conditions:
1. Leaching in the presence of hydrochloric acid (1500 kg/t)
2. Leaching in the presence of sulfuric acid (kg/t)
3. Leaching in the presence of hydrochloric acid in a salt solution of high concentration (1500 kg/t HCl, 2 M MgCl2)
4. Leaching in the presence of hydrochloric acid and SO2in a salt solution of high concentration (1500 kg/t HCl, 2 M MgCl220 kg/t SO2)
The tests were carried out in a glass reactor with a volume of 2 l, equipped with an oil jacket, through which circulates the oil from thermostat to a certain temperature. All testing was carried out at 85°C. in the first stage, received the slurry of 300 g of the ore in the form of a 30% suspension (solid/solid + water) in the water. Suspended suspended using a mixer with a steel floor and removable polypropylene blades. The acid was added in 10 portions at intervals during the 1 h Sample suspension with a volume of 40 ml was collected at the end of each interval to determine the yield of extraction of metals). In the original suspension was added to the uranyl magnesium chloride, while anhydrous magnesium chloride was added to the mixture with acid to provide a constant level of magnesium chloride in the course of the tests in a salt solution of high concentration. If necessary, the addition of sulfur dioxide was controlled using a mass flow meter of Bronkhorst.
A. The test results saprolite ore
On Fig and 21 shows the efficiency of the former is racchi Nickel and cobalt, observed at test saprolite ore respectively. In chloride environment observed higher yields of extraction of both metals regardless of whether the high activity of acid chloride ions or education bisulfate complex in sulphate environment. The efficiency of extraction of approximately 10% is observed when the initial salt solution compared to leaching only in dilute hydrochloric acid. Adding sulfur dioxide does not affect the efficiency of extraction of Nickel, although it leads to some improvement in the efficiency of extraction of cobalt.
On Fig shows the profile extraction of all metals in saline solution with high concentration. Adding small amounts of acid from saprolite selectively extracted Nickel, then manganese and magnesium. The selectivity decreases with increasing amount of added acid to 26 kg N+/t, adding acid more than 26 kg N+/t does not affect the profile extraction.
B. The results of the tests of iron containing ore Jacaré
On Fig-25 shows the results of the study Leonidovich ores. The results of extraction of Nickel are similar to the results of the tests saprolite ore. However, in the case limonadovy ore has seen a significant increase efficiency extracti is in the chloride environment and a significant difference in the results of extraction of hydrochloric acid and sulfuric acid. As in the case of saprolite ore, there is a 10% increase in the efficiency of extraction in a salty environment and the absence of influence of sulfur dioxide. Increasing the efficiency of extraction With observed when adding sulfur dioxide in saline. On Fig shows little selectivity in saline solution with high initial salt concentration. The profile extraction is practically not affected by the addition of acid over 26 H+/so
C. the test Results silicate ore Jacaré
Profiles of extraction of Nickel and cobalt are shown in Fig-28. The obtained results are similar to results of tests of iron containing ore.
The results of the evaluation of the dynamic characteristics of minerals:
- Significant increase in the efficiency of extraction of Nickel is observed when replacing sulfuric acid hydrochloric acid salt system. Similar results were obtained in the case of cobalt.
- Adding sulfur dioxide leads to an increase in the effectiveness of the extraction of cobalt.
The efficiency of extraction of Nickel silicate ore Jacaré correlates with the efficiency of extraction of iron, magnesium and manganese, depending on the Nickel content in limonadovy, magnesium silicate phases and phase of manganese hydroxide, respectively.
The efficiency of extraction of cobalt from silicate ores Jacaré to relire only with the efficiency of extraction of manganese and does not depend on the distribution of cobalt in different phases.
2. The characteristic crystallization
Currently little data on the solubility of magnesium salts in acidic chloride-sulphate or chloride-sulfate water systems. Such information is necessary to determine the operating conditions and the integration of the various nodes in the system. The main parameters include:
the concentration of the acid,
the concentration of chloride and
the concentration of sulfate/sulfite.
First, choose the less complex two-phase system based on sulfate, i.e. the system does not contain the gaseous phase. The original solutions were obtained when a constant concentration of magnesium chloride and various concentrations of magnesium sulfate. At elevated temperatures add sulfuric acid prior to sedimentation. In the resulting solution to determine the content of Mg2+, Cl-, SO42-and free acid, and the resulting number is used to calculate the content of the compound of magnesium and sulfate, while in the solid determine the content of Mg2+, Cl-, SO42-.
Characterization of crystals
The integrated circuit includes restrictions on operating conditions of the mold and the properties of the resulting solids. The most important characteristics of the crystals, which needs to be quantified, presents neither the e:
- The distribution of particle sizes: to obtain a fluidized bed in the air you have a narrow distribution of particle sizes with a sufficiently large average size. Otherwise, the product is subjected to thermal decomposition in a rotary kiln.
- Crystallohydrate water: requires a minimum degree of hydration.
- The inclusion of fluid leakage mother liquor should be kept to a minimum.
- Filtration: ability to filter is dependent parameter and can be improved by satisfying the above criteria.
It is assumed that the characteristics of the crystals obtained in laboratory scale (in static mode) differ from those of the crystals obtained in the reactor in a continuous mode.
The crystals obtained in laboratory scale (static mode) are usually fine (particle size of 10 μm to form agglomerates, as shown in Fig. Results chemical analysis the molar ratio of magnesium/sulfate is approximately 1 (~17% Mg + ~67% SO4), and the content of chloride is less than 2%. The crystals shown in Fig, obtained at 110°C by adding concentrated sulfuric acid to a solution of 6 mol/kg MgCl2. Thus obtained crystals are too small for analysis of individual crystals (the minimum size of which shall be 50 μm), however, data obtained using chemical analysis and x-ray diffraction analysis powder x-ray), demonstrate compliance with the bulk of the product kieserite (MgSO4·H2O).
3. Test the system with a closed cycle
Test the system with a closed cycle is used to evaluate the mutual influence of leaching and crystallization, which are the two main stages of the method according to the present invention. The stage of neutralization is used to control the accumulation of iron and Nickel in the solution for the recirculation system. Each cycle includes a sequence of stages of leaching, neutralization and crystallization using in each stage of the solution obtained at the previous stage. The sequence of stages is repeated several times to achieve equilibrium.
The difference in the solubility of magnesium sulfate in the leach solution compared to the solution for crystallization is sufficient for the distribution of additional magnesium entering the system. The only possibility of removing magnesium from the system is crystallization. The difference in solubility increases due to different crystallization temperature (110°C) and temperature leaching (85°C).
Tests saprolite ore Jacaré is carried out in a confined t the glue when the density of solids of 10% (solid/solid + water).
Extraction of Nickel exceeds 90%, and the initial concentration of hydrochloric acid is supported by the sequential addition of sulfuric acid and removing magnesium sulfate during crystallization. The remote part (outlet) of the solution after crystallization is used to maintain the concentration of iron and Nickel in the primary cycle, but after three cycles of compensation water balance in the primary cycle is crucial when carrying out the process at laboratory scale (static mode). However, the results obtained after the first three cycles (table 2) indicate that a constant concentration of the starting reagent (hydrochloric acid) can be maintained by adding sulfuric acid to precipitate magnesium sulfate.
The composition saprolite ore:
The density of the leach solution: 10%.
There is also the formation of a certain number of crystals of magnesium sulfate during neutralization to remove iron from the outlet stream. However, such crystals are again dissolved and sent to a recycling system for flushing the final cake small amount of water.
Table 3 shows the compositions of the solids formed during crystallization during the last cycle of the two tests in the system for cotim cycle, held at 85°C and 105°C, respectively. In both cases there is a salt of magnesium in a molar ratio of magnesium/sulfate, close to unity. The results of x-ray analysis (see Fig) indicate that the salt is deposited at an elevated temperature, consists mainly of kieserite (MgSO4·H2O).
|The compositions of the solids formed in the mould|
|*the water content was determined by subtracting the total content of the components is 100%.|
4. Tests with a direct replacement of sulfuric acid to sulfur dioxide
The following procedure describes the use of sulfur dioxide for the regeneration of hydrochloric acid in a mixed chloride/sulphate system using the obtained solution for leaching of precious metals from oxide or sulfide ores.
In the first stage of regeneration of acid required iron (3+) for use as a carrier/sorbent for gaseous sulfur dioxide. The main amount of iron goes into solution in the form of Fe (3+) at the stage of leaching of the ore, as occurs, for example, by leaching of oxide ores such as Nickel limonite. However, if the principal amount of iron goes into solution in the form of Fe (2+), for oxidation of ferrous iron to ferric iron required oxidant (such as oxygen).
This is followed by a stage of regeneration of acid, in which the absorption of sulfur dioxide is accompanied by a release of sulfuric acid in the solution:
In a mixed chloride/sulphate system, the difference in solubility of the chloride and sulfate used the La regeneration equivalent of hydrochloric acid, consumed during leaching. Leaching of magnesium from laterite oxide ores flows the following reaction:
Below is a General scheme of the reaction at the stage of regeneration of the acid:
Similar reactions occur and in the leaching of other metals that can be used when developing a method of regeneration of an equivalent amount of hydrochloric acid consumed in the leaching step. The precipitated salt (MgSO4·H2O, described in the previous example) is subjected to thermal decomposition to regenerate an equivalent amount of gaseous sulfur dioxide, thus providing a self-sustaining process. In another embodiment, the sulfur (or another cheap source of sulfur) burn in air with the formation of gaseous sulfur dioxide, which is used as described above, there is eliminated the necessity of turning gas into sulfuric acid on the costly device for producing sulfuric acid.
All of the above reactions are carried out in laboratory scale. However, at lower pH (apparently, due to the continuation of the reaction rate of the reaction (6) can be reduced. To accelerate the reaction (6) on an industrial scale it is possible to use a catalyst, such as copper ions in solution, graphite or even ug is eh.
A sample of Nickel laterite provided by the company Jacaré Brazil. It is established that the material contains a certain amount of magnesium, which will consume a significant amount of acid for acid leaching. So get salt solution of magnesium chloride at saturation of 80% at 80°C. Then add other ingredients salt solution according to mass balance, received the pulp of the laterite in the specified environment and pH brought up to 0,5 adding hydrochloric acid. The output of the extraction of Nickel and magnesium from laterite is more than 80% at the time of contact in the system for 3 hours a Saturated solution after leaching bubbled with gaseous sulfur dioxide, when this occurs the precipitation of magnesium, at least in quantity, which is obtained after leaching of laterite sample. Get sediment in the form of a crystalline monohydrate magnesium sulfate. At the same time restores the concentration of acid in the environment after leaching, providing leaching of the next sample.
Sulfate is calcined to form magnesium oxide, which is excessive in relation to the requirements for internal processes. Some amount of magnesium oxide used for the deposition of iron, Nickel and cobalt from a solution to Vyselki the project in the form of two types of hydroxides - hydroxide and iron oxide hydroxides of Nickel and cobalt. The product containing iron, cast, you get a main product in the form of a mixture of Nickel and cobalt.
The data of table 4 indicate that gaseous sulfur dioxide can in principle be used to replace sulfuric acid at the stage of crystallization, provided that there is a sufficient amount of iron ions (3) and is used in sufficient time for the reaction.
|Replacement of sulfuric acid to sulfur dioxide|
|Reagents||The reaction time||The final amount of acid (HCl)|
|Gaseous sulfur dioxide 0% + Sulfuric acid 100%||2 hours||163 g/l|
|Gaseous sulfur dioxide 25% + Sulfuric acid 75%||2,25 h||159 g/l|
|Gaseous sulfur dioxide 50% + Sulfuric acid 50%||4.5 hours||157 g/l|
Based on these data we can draw the following conclusions:
The concentration of the original Rea is enta (hydrochloric acid) supports constant in the main loop when the precipitation of magnesium sulfate concentrated sulfuric acid, that ensures efficient extraction of Nickel during the first stage of leaching.
The solubility of magnesium sulfate in the mould is less than its solubility in the leach solution, particularly at elevated temperatures and high concentrations of magnesium chloride in the mould.
Crystals formed during crystallization represent monohydrate magnesium sulfate (keseric) with the inclusion of a number of Nickel and chloride. The inclusion of chloride occurs as a result of capture of a solution of fine sediment, and the inclusion of Nickel can be reduced to a minimum when carrying out the crystallization at elevated temperature slightly below the boiling point of the solution at atmospheric pressure).
- Gaseous sulfur dioxide can be used for the systematic replacement of an equivalent amount of sulfuric acid, provided that there is a sufficient number of ions of trivalent iron for absorption of gaseous sulfur dioxide.
Another variant of implementation of the present invention refers to the use of hydrochloric acid (chloride) for oxidative or non-oxidative leaching of sulfide concentrates, such as zinc-containing ore, as described below. Although the use of non-oxidizing processes the La extraction of base metals from sulphide concentrates is not in itself new (sulphate environment: S C Copper Process, Kawulka and others (1978), chloride environment: Molleman and others (1998)), method of regenerating acid is not known in the art. Non-oxidative method for leaching salt solutions with a high concentration in combination with an integrated stage regeneration acid is also not known in the art. Valuable non-ferrous metals, such as zinc leached from the sulfide concentrates in the original solution of hydrochloric acid. Leached non-ferrous metal obtained as a commercial product. The kinetics of leaching is rapid, and metals such as copper, to form a solid phase (such as CuxS), and are removed from the tail fractions if necessary, using the oxidative leaching process. An additional advantage of non-oxidizing conditions is the possibility of separating elemental sulfur using a standard Claus process (oil and petrochemical industry).
The main agent for leaching is the hydronium ion in the original chloride environment, which is determined by the accumulation of salts, especially salts of non-ferrous metals, such as zinc chloride, in primary system process.
At the stage of crystallization is a low solubility product, sulfate or sulfite of nonferrous metal, such as zinc, in the original chloride salt Rast is the op to remove leached precious metals from solution. Crystals of sulfate or sulfite contain a minor amount of water of hydration and is suitable for thermal decomposition with the formation of oxide (for use as an internal neutralizing agent), which can be used as a commercial product or part which can be dissolved in sulfuric acid (formed during electrolysis) and used for direct electrolysis of metal.
Regeneration of hydrochloric acid and extraction of non-ferrous metal, such as zinc, as described above, are not associated with removing excess water in the process of evaporation, because the metal is obtained from the crystalline cake with low water content and hydration water.
The present invention is based on the significant difference in the solubility of zinc sulphate and chloride systems, the latter is almost 2 times higher at 100°C (see experimental data published in the work Linke and Seidell (1965)). It was found that in chloride environment, this phenomenon is amplified and used to substantially reduce the solubility of zinc in chloride environment, while adding a sulfate or sulfite in the form of gaseous sulfur dioxide or sulfuric acid as an intermediate reagents for admission to the recirculation system is formed and precipitated sulfate or sulfite qi is ka with simultaneous regeneration of hydrochloric acid in solution. Moreover, the obtained experimental data it follows that gunningi (monohydrate zinc sulfate) is the preferred product of crystallization in a wide range of temperatures (typically at about 60°C), which allows to minimize the amount of energy required for calcination to obtain zinc oxide (which is partially directed into the recirculation system for internal neutralizing agent) and regeneration of sulfur dioxide. A simplified reaction scheme is shown below:
Crystalline product containing less than 0.01% of the total chloride receive the described method to illustrate the effectiveness of this technology, i.e. to obtain zinc oxide high purity as a commercial product (a certain amount is used as an internal neutralizing agent) or for re-dissolution of zinc oxide in sulfuric acid (coming after electrolysis) and direct electrolysis of zinc from the resulting solution. Also the regeneration of relatively expensive hydrochloric acid with the use of relatively cheap and available reagent, i.e. gaseous sulfur dioxide or sulfuric acid. The precipitated zinc sulfate is the ideal product for decomposition in the reactor with PS is vooruzhennym layer. Partial rehydration monohydrate (for optimized hydrate for thermal decomposition) is carried out at the monitoring time contacting a crystalline precipitate with a suitable aqueous mother liquor. If direct use of sulfur dioxide is technically promising, the technology of regeneration of sulfuric acid from sulfur dioxide, obtained by calcination of sulfate sulfur, is well known and is a means of deposition of gunningi, which is experimentally feasible. In any case, do not require additional reagents for processing, because sulfur dioxide is a product of the stage of thermal decomposition. The main advantage of using zinc sulfate with low content of water of hydration for decomposition to zinc oxide is a significant reduction in energy consumption compared to pyrohydrolysis solution of chloride of zinc.
Favorable kinetics of leaching is achieved by processing the original rough concentrate, which allows use of the method according to the invention for leaching of valuable metals such as zinc, silver and lead from sulphide ores. The most important is fast (less than 1 h) kinetics of leaching at a temperature of 85°C in 4 M solution of hydrochloric acid (Fig).
Schematic diagram of the process shown is as Fig, in which the hydrochloric acid leaching is used to solubilize the securities of zinc sulfide material in a non-oxidizing stage, and the zinc is then sequentially removed in the form of a crystalline salt at the stage of regeneration of the acid. For the extraction of zinc sulfate in sulfuric acid is not required, the processing of the saturated solution to leach the neutralizing agent. Sulfate is deposited preferably in the form of a monohydrate, and not in the form of uranyl (as it seems obvious to a person skilled in the art). The main advantage lies in the transformation of sulfate in the oxide, as while there is a significant savings in energy consumption compared to uranyl. Impurities such as iron, can be removed by hydrolysis after neutralization of the excess acid zinc oxide from the recirculation system obtained after calcinations.
A similar result is achieved by direct addition of gaseous sulfur dioxide (instead of sulfuric acid) when bubbling saturated solution for leaching. The advantage of this treatment is evident in the case of annealing of elemental sulfur or particulate sulfate with the formation of sulfur dioxide in comparison with the use of ready-made commercial sulphuric acid.
This method is based on the new is the principle of regeneration of reagents, i.e. reuse pixelates and a neutralizing agent in a recirculation system process.
Preliminary estimates of the balance of mass/energy showed a significant advantage of this principle compared to the standard processing of sulfide ores.
The most important are the following factors:
as a concentrate, you can use the purified concentrate or less clear (rough) concentrate (higher degree of extraction of precious metals),
- non-oxidative leaching is carried out at any desired concentration of HCl, while maintaining the overall level of chloride in the rest of the system,
- Cu re-deposited in the form of CuxS at the stage of leaching at atmospheric pressure, i.e. if necessary, the copper is extracted from the residue of waste rock, if it justifies the cost,
- Pb leached from the system in the form of chloride complexes and precipitate in the mould in the form of sulphate. PbO formed at the stage of thermal decomposition, effectively extracted from the residue, obtained at the stage of re-leaching of ZnO in the form of purified salt PbSO4,
- ZnSO4·H2O is formed in the mold by adding H2SO4in chloride solution due to differences in the solubility of sulfate and chloride:. Main Ave the property of this reaction is the property of the original salt solution to bind free water, this created digidrirovannye salt (less than 1 mol H2About 1 mol of zinc), which significantly reduces the energy consumption at the stage of decomposition compared to salts comprising a large number of hydration water, such as ZnSO4·6H2O,
- established the feasibility of direct use of sulfur dioxide (formed at the stage of thermal decomposition) as a starting reagent to precipitate ZnSO4·6N2On assuming the presence of sufficient amount of trivalent iron for absorption of sulfur dioxide in the solution phase. Thus at the stage of crystallization requires the addition of an oxidant (such as oxygen) to oxidize the ferrous iron (obtained by non-oxidative leaching) to ferric iron,
- the above stages of crystallization and thermal decomposition include reagents in stoichiometric ratio, and it requires no additional add sulfuric acid or sulfur dioxide (except for the analysis of products for specific industrial setting),
- part of the salt solution divert from the main thread (before crystallization) to limit the accumulation of iron in the source system; a proportionate amount of zinc oxide (obtained at the stage of thermal decomposition) comes in recirculate the pension system to neutralize the free acid in otodrom thread containing impurities, which provides saturation of precious metals (silver, Nickel, cobalt, cadmium) zinc dust before removing iron,
the hydrolysis of iron is carried out at atmospheric pressure or under reduced pressure in an autoclave, by hematite and/or goethite (presumably in the form of akaganeite); another advantage of the salt solution with high concentration is extremely small content of free water, which in turn provides the dehydration of oxides/hydroxides of iron and the precipitation of hematite at much lower temperatures compared to the standard sulphate systems,
- the main mass of zinc oxide (excluding run-off stream to neutralize) arrives at the stage of re-leach, on which the oxide is dissolved in the presence of sulfuric acid in the anolyte flowing from electrolysis system; the acid is in a stoichiometric ratio, and does not require adding more acid or neutralizing agent (except for the analysis of products obtained in an industrial setting),
- throughout the system there is no need for otodrom thread, or you need to take only a small amount of solution, as sodium sulfate accumulates to saturation and is deposited in the most concentrated section of the system
- is since there is no need for otodrom flow or need to take only a small amount of solution, the removal of water is achieved by using a multi-effect evaporator,
on Fig shows the chloride and sulfate closed system, integrated in the overall process scheme.
Laboratory tests include 4 stages, i.e. leaching, crystallization, thermal decomposition and re-leaching of calcined zinc oxide. Evaluate the distribution system the following items (lower limit of detection was 10 hours/million): aluminum, calcium, cadmium, cobalt, chromium, copper, iron, magnesium, manganese, Nickel, lead, silicon and zinc.
The test conditions are determined by the simulation results of the balance of mass/energy. An important difference between computer simulation and real was the fact that computer simulation is performed on the example of the pure concentrate (approximately 50% zinc), and laboratory simulation using less clear rough concentrate (approximately 5% zinc).
Metallurgical analysis at this initial stage is carried out only for the samples obtained at the stage of non-oxidative leaching at atmospheric pressure and after they are processed in the mould. Non-oxidizing plant for leaching is shown in Fig.
Vaporous phase is absorbed in a scrubber containing ferrous sulfate (3), with the purpose of the transformation of the entire hydrogen sulfide (H 2S, obtained by leaching into elemental sulfur. The vacuum scrubber is more appropriate compared to high pressure in the reactor leaching, i.e. due to the possibility of leakage of hydrogen sulfide in the environment. Air is bubbled through the reactor leaching with the objective of ensuring the removal of hydrogen sulfide from the system, i.e. to shift the reaction to the right:
On Fig shows a typical kinetics of leaching during testing at low density solids in the selected fraction with a specific particle size (fine particles were removed). Kinetics in the presence of 4 M hydrochloric acid proved to be quite optimal. The presence of periods of inhibition during the other two tests is a consequence of the polarization of the surface in the anode direction, i.e. due to the presence of oxygen (bubbling), thus, later bubbling air through the solution must be stopped.
The main advantage of using crystallization (ZnSO4·H2O) in the system is the lack of necessary neutralization after leaching, i.e. the leaching can be carried out at any concentration of HCl, i.e. to ensure rapid kinetics. On Fig shows a typical product of crystallization of the salt R is the target in the presence of concentrated H 2SO4. The main part of the product is hunnington [Zn(SO4)(H2O)], but according to x-ray analysis there is a high degree of crystallinity type of plaster. When extremely high concentrations of NaCl deposited a small amount of changeit [Na2Zn(SO4)2·4H2O].
To prevent the influence of other elements on the stage of crystallization solution concentration is maintained at the level lower than the solubility of the sulfate or sulfite, which is achieved in the processing of run-off flow, for example, from a saturated leach solution at saturation (cementing) and/or neutralization. For the specified fallback, you can use part of the product of calcination.
Water balance process support in the process of evaporation to control the concentration of salt solution, compensation adding water at various stages, such as the flow of leach solution, water for washing, etc.
Leaching of sulphide ores
The method described below in example zinc sulfide.
Use the concentrate obtained by flotation of sphalerite ore deposits of Gamsberg (South Africa). The concentrate is leached in 4 N. hydrochloric acid in the presence of a source of zinc chloride in solution at 85°C. the Leaching was completed in 15-30 minutes Initial concentration of zinc chloride ratio(concentrate/Sol) is chosen so that to get rich leach solution at 80% saturation with chloride of zinc. The leach solution is mixed with 98% sulfuric acid in a beaker with stirring, when this occurs the precipitation of zinc sulfate in an amount equivalent to the amount of leached zinc. The precipitate is crystalline zinc sulfate in the form of a hemihydrate, which corresponds to the calculated amount of salt. Salt optional calcined to obtain the oxide under suitable temperature, for example, 750°C, in air, thus receive a gaseous phase containing at least 20% of sulfur dioxide, suitable for use in a device for producing sulfuric acid or for direct reuse during crystallization.
The main solution containing zinc, iron, sodium, in the form of chlorides and sulfates, get at 60°C, then the solution is added a stoichiometric amount of sulfuric acid. These tests carried out with a dual purpose: determining the solubility of the main components in the solution and determining the amount and purity of the crystals formed during the addition of sulfuric acid. The research results shown in table 5.
|The results of the study of the solubility and crystallization|
|Zn g/l||Fe g/l||Na g/l||Cl g/l||SO4g/l||Zn||Fe||Na||Cl||SO4|
When the test sample 20050324D6 crystal formation was not observed due to the low initial concentration of zinc. The results obtained indicate that in systems containing Zn, can be used successfully precipitation crystallization for the primary regeneration of the reactants.
Getting chloride solution with a high concentration of acid (sverhchistoty solution)
Chloride salt solution is mixed with sulfuric acid or sulfur dioxide to obtain a salt solution containing hydrochloric acid in sverhsekretnoj concentration (i.e. the concentration at which the concentration of hydrochloric acid exceeds the azeotropic concentration). This process does not require sophisticated equipment for elegance or expensive reagents. Thus, a simple and cheap method of obtaining solutions with extremely high acidity, for use in certain processes, such as specific ways of dissolution, which is used in the purification of platinum group metals.
The resulting acidity of the acid, which can be below and above the azeotropic concentration is determined by the nature of the chosen chloride.
Getting chloride salt solution with high acidity
Magnesium chloride is dissolved at 100°C to a concentration of approximately 42,3 g/100 g saturated solution. Adding H2SO4in extreme cases, a complete precipitation of magnesium in the form of the monohydrate is formed approximately 50,3 g of salt in 49,7 g of water and 32.4 g of HCl having a pH of 39%.
Getting chloride salt solution with high acidity
Magnesium chloride is dissolved at 80°C to a concentration of approximately 84,4 g/100 g saturated solution. Adding H2SO4in the case of deposition of 75% of the zinc in the form of the monohydrate is formed approximately 71,1 g salt to 28.3 g of water and 33.9 g of HCl having a pH of 54%.
The present invention has been described in detail on the example of private variants of its implementation, but the experts in this field will be clear that there are many possible modifications and other changes that do not go beyond the nature and volume of the mA of the present invention in the framework of the attached claims.
1. Method of leaching the metal from its containing ore, which
carry out the leaching of the ore in the presence of hydrochloric
acid with the formation of soluble metal chloride in the leach solution,
add sulphuric acid in the leach solution with the formation of the leach solution precipitated solid metal sulfate, in which the source of the metal is mainly ore,
carry out the regeneration of hydrochloric acid simultaneously with the deposition of solid metal sulfate and remove the solid metal sulfate from the leach solution and
return the regenerated solution of hydrochloric acid with a high concentration of chloride ions and a low concentration of sulfate ions on the stage of leaching.
2. The method according to claim 1, in which the metal sulfate is characterized by the formula MeSO4·yH2O, where
Me denotes a metal,
and 0 or more.
3. The method according to claim 2, in which the value of y is from 0 to 3.
4. The method according to claim 2, in which y is 0.
5. The method according to claim 2, in which y is 1.
6. The method according to claim 1, in which the ore is predominantly an oxide or silicate ore containing base metal.
7. The method according to claim 6, in which the ore is an oxide of zinc ore.
8. the procedure according to claim 1, in which ore is lateritic Nickel ore.
9. The method according to claim 8, in which the laterite ore is sapralieva or Limonova ore.
10. The method according to claim 1, in which the ore is a sulfide ore.
11. The method according to claim 1, in which the ore is an ore of titanium.
12. The method according to claim 1, in which the ore is aluminum ore.
13. The method according to claim 1, in which the metal sulfate is precipitated from the leach solution.
14. The method according to claim 1, in which the metal sulfate is extracted from the leach solution by the method of crystallization by evaporation.
15. The method according to claim 1, wherein the metal is chosen from the group comprising Zn, Cu, Ti, Al, Cr, Ni, Co, Mn, Fe, Pb, Na, K, CA, platinum group metals and gold.
16. The method according to claim 1, in which the metal composition of the metal sulfate is the metal leached from the ore.
17. The method according to claim 1, which further carry out the decomposition of the metal sulfate to extract leached from the ore of the metal.
18. The method according to claim 1, in which the metal composition of the metal sulfate is less valuable metal than the metal leached from the ore.
19. The method according to p, in which the metal composition of the metal sulfate is magnesium.
20. The method according to claim 1, in which the metal sulfate is treated under conditions in which the formed sulfur dioxide, or sulfur trioxide, or a mixture.
21. The method according to claim 1, in which valuable meta is l extract regardless metal salt, formed by adding sulphuric acid.
22. The method according to claim 1, in which the regenerated hydrochloric acid is suerasefrania acid.
23. The method according to claim 1, wherein the solution of metal chloride is a solution containing a chloride of an alkali metal.
24. The method according to claim 1, wherein the metal sulfate is the sulfate of an alkali metal.
25. The method according to claim 1, in which the recirculation of regenerated hydrochloric acid leaching process.
26. The method according to claim 1, in which the hydrochloric acid used to leach the ore is present in the composition of the salt solution.
27. The method according to p, in which the salt solution used from approximately 10% to approximately 90% saturated solution of magnesium chloride, from about 10% to about 90% saturated solution of zinc chloride or from about 10% to about 90% saturated solution of chloride of another metal.
28. The method according to p, in which the salt solution used from approximately 25% to approximately 40% saturated solution of magnesium chloride, from about 25% to about 40% saturated solution of zinc chloride or from about 25% to about 40% saturated solution of chloride of another metal.
29. The method according to claim 1, in which the metal sulfate COI is lsout to obtain a metal oxide.
30. The method according to claim 1, in which the metal sulfate is subjected to thermal decomposition to obtain a metal oxide and sulfur dioxide, sulfur trioxide, or mixtures thereof.
31. The method according to clause 29, in which the metal oxide is chosen from the group comprising magnesium oxide, zinc oxide, iron oxide and aluminum oxide.
32. The method according to item 30, in which the metal oxide is chosen from the group comprising magnesium oxide, zinc oxide, iron oxide and aluminum oxide.
33. The method according to item 30, in which sulfur dioxide, sulfur trioxide, or their mixture is used to produce sulfuric acid, which in turn are returned to the leaching process for the regeneration of hydrochloric acid.
34. The method according to claim 1, in which the metal is leached from the ore at a temperature of from about room temperature to about the boiling point of a solution of metal chloride to leach.
35. The method according to claim 1, in which one or more leached from the ore metals selectively removed from the solution before the stage of formation of metal sulfate.
36. The method according to p, which selectively remote metal is cobalt, Nickel, platinum group metals, gold, silver and/or copper.
37. The method according to claim 1, in which impurities of iron and/or other residual impurities formed after solubilization ore, partially or completely removed from the leach solution.>
38. The method according to clause 37, in which impurities of iron and/or other residual impurities are removed by the method of solvent extraction with subsequent pyrohydrolysis.
39. The method according to § 38, in which impurities of iron and/or other residual impurities are removed by hydrolysis.
40. The method according to claim 1, in which the concentration of sulfuric acid is at least 30%.
SUBSTANCE: procedure consists in processing refractory ore and concentrates with chlorine at presence of water and complex former in kind of sodium chloride, in converting gold into solution, in separating solution from precipitated sediment, and in washing sediment with water producing flush water. There are processed refractory ore and concentrates with low contents of gold and uranium, where uranium is additionally extracted. Also, for processing there is used chlorine in atomic or molecular state. Chloride or sodium sulphate are used as complex formers. Processing is carried out at weight ratio L:S (liquid: solid) (1-1.5) during 1-2 hours at temperature 20-70°C with simultaneous gold and uranium passing into solution.
EFFECT: simplified process, reduced power expenditures at maintaining high degree of gold and uranium extraction from poor bases and concentrates.
7 cl, 6 tbl, 6 ex
SUBSTANCE: invention can be used to produce magnesium chloride, silica and red pigment. Serpentinite calcined at 680-750°C is treated with 4-8% hydrochloric acid solution with weight ratio of serpentinite to hydrochloric acid equal to 1:(15-40). The hot pulp is then decanted and filtered. The residue is dried to obtain silica, the filtrate is evaporated and silicic acid is separated. After separating silicic acid in form of sol-gel, hydrochloric acid is added to a solution containing magnesium and iron (III) chlorides until 4-8% hydrochloric acid solution is obtained. The obtained hydrochloric acid solution is used to treat a new portion of serpentinite. Further, the decantation, filtration, evaporation of filtrate, separation of silicic acid and treatment of the obtained solution with hydrochloric acid are repeated 3-5 times using new portions of calcined serpentinite. The solution concentrated that way at 90°C is mixed with serpentinite and filtered. Magnesium chloride is separated from the residue which contains iron (III) hydroxide. Said residue is treated at 350-400°C to obtain red pigment.
EFFECT: invention simplifies the processing serpentinite, improves environmental safety and reduces expenses and wastes.
1 dwg, 1 ex
SUBSTANCE: invention refers to procedures for extracting valuable metals from wastes including wastes of refining production. The procedure for processing silver containing lead wastes for extracting silver and lead in form of products consists in leaching wastes with solution containing hydrochloric acid to transit lead into solution and silver to sedimentation. Also leaching is carried out in three stages. At the first stage leaching is peformed with solution of lead chloride (PbCl2) at temperature 0°-25°C in concentrated hydrochloric acid (HCl) by placing wastes in this solution heated to temperature 40°-80°C. Major part of lead transits into solution. During the second and the third stages non-dissolved wastes are leached in 30-42% HCl and successively filtered till pure powder-like silver is produced in a non-soluble residue. Upon the first stage solution is cooled to 0°-25°C, crystals of PbCl2 are extracted out of it and combined with solutions of HCl after leaching at the first and the third stages; a new portion of wastes is directed to leaching. Implementation of this procedure at a lead plant of average output can collect yearly income of approximately 100 million dollars from sale of lead chloride.
EFFECT: raised efficiency of wastes processing, additional economic profit from implementation of this procedure at various metallurgical productions.
4 tbl, 2 ex
SUBSTANCE: invention refers to procedure for leaching precious metal from ore containing said precious metal. The procedure consists of three stages: leaching ore at presence of hydrochloric acid with production of soluble chloride of metal in a solution for leaching, in adding sulphur dioxide into the solution for leaching, in extracting metal sulphate or metal sulphite from the solution for leaching and in regenerating hydrochloric acid. As ore there can be used oxide ore of non-ferrous metal, such as oxide zinc ore, laterite nickel ore, such as saprolite or limonite, sulphide ore or titanium ore. Precious metal is chosen from a group including Zn, Cu, Ti, Al, Cr, Ni, Co, Mn, Fe, Pb, Na, K, Ca, metals of platinum group and gold. Precious metal or less precious metal, such as magnesium, can be a metal in composition of metal sulphate or metal sulphite. Regenerated hydrochloric acid is directed into a re-circulation system in the process of leaching.
EFFECT: increased efficiency of process.
45 cl, 36 dwg, 5 tbl
SUBSTANCE: procedure for processing titanium-magnetite concentrate consists in leaching concentrate with sulphuric acid and heating in presence of metal iron, in transfer of iron and vanadium into leaching solution and in concentrating titanium in residue. Further, solution is evaporated; iron containing residue is extracted and subjected to pyrolysis producing iron oxide and regenerated hydrochloric acid. Titanium containing residue is dried and baked producing a titanium product. Also titanium-magnetite concentrate is leached at concentration of hydrochloric acid of 15-19% and temperature 95-105°C. Iron-vanadium product in form of sediment of iron and vanadium hydroxides is settled from leaching solution by means of processing with ammonia solution at pH 2.4-2.8; there is produced iron chloride solution (II). Produced iron chloride solution is evaporated; iron containing sediment is extracted and the left sediment is subjected to pyrolysis. Titanium containing sediment is baked at temperature 700-800°C.
EFFECT: production of pure iron oxide (Fe2O3 not more than 99,3 wy %).
3 cl, 1 tbl, 6 ex
SUBSTANCE: method involves treatment of the material by washing with water, burning the insoluble residue and leaching the ash. Before leaching, the ash undergoes secondary treatment by washing with water in solid to liquid ratio equal to 1:0.7-2.5.
EFFECT: reduced volume of pulp obtained during leaching, increased extraction of noble metals and recycling of potassium chloride.
2 tbl, 2 ex
SUBSTANCE: invention refers to extraction methods of precious metals and can be used for extraction of precious metals from mineral raw material containing chlorides of alkali and alkali-earth metals, e.g. sludges of potassium production. Extraction method of precious metals from clay-salt waste - sludges of potassium productions - containing chlorides of alkali and alkali-earth metals involves bulk concentrate obtained from them, roasting, leaching of precious metals from stub end and sorption of precious metals. Bulk concentrate is obtained till content of chlorides is 15 to 30%. Before roasting, the concentrate is granulated and subject to roasting at temperature of 500-950°C. Precious metals are leached from stub end by means of salt acid solution.
EFFECT: increasing complex extraction of precious metals.
5 tbl, 4 ex
SUBSTANCE: development method of ruthenium concentrate includes thermal treatment of it in mixture to sodium peroxide in iron pans at mass ratio of sodium peroxide to concentrate (0.8-2.0) and gradual temperature increase up to 500-600°C. Then it is implemented treatment of thermal treatment product in water and dissolving in hydrochloric acid with transferring and concentration of rutenum in chloride solution. After product thermal treatment in water received pulp is treated by deoxidising agent, in the capacity of which it is used Na2SO3 or C2H5OH, up to value achievement of oxidation-reduction potential equal to minus (100-200) mV (relative to chlorine-silver reference electrode). Received sediment is separated up to formed aquatic alkaline solution and subject to dissolving in hydrochloric acid.
EFFECT: achievement of deep development of concentrate with its following concentration in chloride solution with low saline saturation.
1 tbl, 1 ex
FIELD: process engineering.
SUBSTANCE: invention relates to processing of Au-Sb antimony-based gold containing alloy. Proposed method comprises dissolving the alloy by hydrochloric acid, extracting antimony oxychloride chloride solution by hydrolysis and gold by sorption. Note here that alloy dissolution is effected by hydrochloric acid with hydrogen oxide solution. Extracted antimony oxychloride is dissolved in dihydroxysuccinic acid and resulted solution is directed to electro hydrolysis to produce cathode antimony. During hydrolysis the solution is regenerated to further use in dissolution. Gold is extracted by sorption from the solution containing 60 to 65 mg/l of gold with the help of high-basic anion exchanger AB-17.
EFFECT: treatment of alloys with wide range of noble metal concentrations within 0,1 to 1,3 %.
7 cl, 4 tbl, 1 ex
FIELD: process engineering.
SUBSTANCE: invention relates to process engineering and can be used for processing antimony-based alloys containing noble metals in concentrations over 0.1%. Proposed method comprises dissolving alloys in solution containing acid and extracting noble metals from said solution by cementing. Prior to dissolving alloys, lead is remove therefrom by processing with solvent. Alloys are dissolved by solution containing hydrochloric acid and hydrogen dioxide or sodium persulphate. Noble metals are cemented by antimony-based alloys with minor concentration of noble metals or cathode antimony powder with grain size varying from 100 to 74 mcm, or by gold-antimony flotation concentrate with grain size varying from 100 to 74 mcm to produce an alloy enriched with noble metals cements noble metals. Now, noble metals are extracted from obtained products.
EFFECT: treatment of alloys with wide range of noble metal concentrations within 0,1 to 1,3 %.
4 cl, 2 tbl, 5 ex
SUBSTANCE: procedure for processing final tailings of galvanic production consists in crumbling, leaching, separation of solution from sedimentation and in extracting heavy non-ferrous metals from produced solution. Also, final tailings are crumbled with mechanic-chemical activation by wet crumbling in form of pulp suspension at pH≤3 and ratio s (solid): l (liquid) = 1:(0.4-1) and temperature 60-90°C.
EFFECT: reduced harmful environmental impact and power expenditures due to elimination of thermal treatment stage at processing final tailings; raised efficiency of extraction of heavy metal compounds.
3 tbl, 1 ex
SUBSTANCE: there are used soluble and insoluble anodes connected to separate sources of current for control over soluble anode dissolution during process of electrolysis and concentration of ions of metal in solution by means of correcting ratio of anode strengths of current of soluble and insoluble anodes at constant value of cathode density of current. Also, constant value of cathode density of current is achieved by constant area of cathode and sum of current strength on the soluble and insoluble anodes.
EFFECT: avoiding labour-intense operation of correction of electrolyte due to equalising cathode and anode current outputs at production of powders of metal.
8 dwg, 3 ex
SUBSTANCE: procedure consists in leaching at atmospheric or raised pressure, in production of effluent and in utilisation of ion-exchanging resins for absorption and extraction of nickel and cobalt. Before extraction of nickel and cobalt effluent in form of solution or pulp is treated with cation or chelate resin possessing selectivity relative to extraction of iron, aluminium and copper for their removal; it also increases pH of solution.
EFFECT: elimination of neutralisation stage of solution, efficient purification of effluent, prevention of nickel losses and avoiding division of solid and fluid phase of formed pulp at laterite ore leaching.
6 cl, 2 dwg
SUBSTANCE: procedure consists in leaching with chloride solution at supply of chlorine, in purification of solution from copper and in production of copper sulphide cake, in extracting concentrate of precious metals and in electro-extraction of nickel from solution. Prior to leaching matte is separated to a sulphide and metallised fractions. The sulphide fraction is subjected to leaching with chloride solution with supply of chlorine. The metallised fraction produced at separation of matte is added into pulp produced at leaching thus performing purification of solution from copper and its withdrawal to copper sulphide cake. Upon purification of solution from copper solution is purified from iron, zinc and cobalt. Copper sulphide cake is roasted and produced cinder is leached. Solution is directed to electro-extraction of copper, while concentrate of precious metals and chamber product are extracted from residue by flotation.
EFFECT: reduced material and operational expenditures and losses of non-ferrous and precious metals.
2 cl, 12 ex, 2 dwg
SUBSTANCE: procedure consists in processing wastes with sulphuric acid at raised temperature, in supplying hydrogen peroxide, in introducing rhenium, nickel and cobalt into leaching solution and in concentrating tungsten, niobium and tantalum in insoluble residue. Further, solution is separated from insoluble residue; extraction of rhenium from solution is leached with secondary aliphatic alcohol. Extract is washed and rhenium is re-extracted with leaching solution upon extraction. Hydrogen peroxide is supplied after main part of nickel and cobalt have passed into solution at maintaining redox potential in interval of 0.50-0.75 V relative to a saturated chlorine-silver electrode, while extraction of rhenium, extract washing and rhenium re-extraction are carried out on 2-5 steps.
EFFECT: increased extraction of rhenium at reduced consumption of oxidant, increased safety of procedure due to separated in time operations followed with release of hydrogen and oxygen.
6 cl, 4 ex
SUBSTANCE: procedure consists in underground leaching nickel with solution of sulphuric acid and in pumping product solution out. Further, acidity of product solution is reduced, and nickel is sorbed on ionite resin with its following desorption. Upon desorption raffinate of nickel sorption is made-up with sulphuric acid and directed to leaching as leaching solution. Also, excessive sulphuric acid is sorbed on separate ionite with following desorption for reduction of product solution acidity. Upon nickel sorption raffinate is made-up with sulphuric acid and with sulphuric acid after operation of its desorption.
EFFECT: simplification of process, increased ecological safety and reduced consumption of sulphuric acid.
1 dwg, 1 tbl
SUBSTANCE: processing procedure consists in supply of charge into slag melt in oxidising (melting) zone of two-zone furnace. Also charge contains source raw material and fluxes, liquid or solid processed slag, carbon containing material and oxygen containing blast supplied in quantities required for complete combustion of carbon and hydrogen with maximal heat release. Before supply of mixture of source raw material and fluxes into the oxidising (melting) zone of the furnace their mixture is preliminary roasted and supplied at temperature 500-1300°C. Melted charge forms slag melt coming into a furnace zone of reduction, whereto oxygen containing blast and carbon containing material are supplied. Notably, they are supplied at amount required for reduction of extracted material into a metal phase and for compensation of heat consumption by means of after-burning gases of the reduction zone above melt, whereupon melt products are tapped.
EFFECT: raised efficiency of melting process and reduced consumption of oxygen and carbon containing material.
3 cl, 4 tbl, 5 dwg, 2 ex
SUBSTANCE: proposed method comprises dissolving wastes in acid electrolyte by applying AC electric field thereto. Dissolving is performed in nitrate or sulphate electrolyte on applying half-wave asymmetric AC industrial-frequency current and on using second electrode made from tantalum or niobium plates. Note here that anodic dissolution is carried at acidity of nitrate electrolyte at the level of 200-250 g/l HNO3, while that of sulphate electrolyte making 150-200 g/l H2SO4 at 20-40°C and current of at least 1 kA.
EFFECT: increased process rate, better ecology.
3 cl, 3 tbl, 3 ex
SUBSTANCE: method involves drying of concentrate and melting in the oven. At that, melting is performed in cylindrical reaction chamber of the oven at bubbling and rotation of the molten metal with oxygen-containing jets in sulphur to oxygen ratio 1:(1-1.1). After melting is completed, the molten metal is separated into slag and matte in collector.
EFFECT: continuous high efficiency method of processing of copper-nickel sulphide concentrates so that high-grade mattes are obtained and content of cobalt in slag is decreased.
SUBSTANCE: method consists in dissolving solubilisated components of ore by means of carrying out two or more successive stages of leaching. The first stage includes leaching at atmospheric pressure (AL), while during the second stage leaching is performed under (HPAL) pressure. In the course of this combined process average fraction of ore (0.075-0.5 mm) (1) is subjected to leaching under atmospheric pressure (AL) thereby producing flow (3) of high dissolved iron, aluminium and residual acid concentration. This said flow (3) is supplied to the next stage of leaching under pressure (HPAL) of fine fraction of ore (<0.075 mm) (4); contained free acid is re-used. Reaction of hydrolysis of iron and aluminium sulphates causes sedimentation of iron and aluminium and, thereby, regeneration of sulphuric acid.
EFFECT: reduced amount of consumed acid used for leaching.
7 cl, 4 dwg
SUBSTANCE: procedure for processing final tailings of galvanic production consists in crumbling, leaching, separation of solution from sedimentation and in extracting heavy non-ferrous metals from produced solution. Also, final tailings are crumbled with mechanic-chemical activation by wet crumbling in form of pulp suspension at pH≤3 and ratio s (solid): l (liquid) = 1:(0.4-1) and temperature 60-90°C.
EFFECT: reduced harmful environmental impact and power expenditures due to elimination of thermal treatment stage at processing final tailings; raised efficiency of extraction of heavy metal compounds.
3 tbl, 1 ex