Processing of gold-bearing inorganic materials including processing of jewellery scrap and gold refining
SUBSTANCE: proposed method comprises melting of initial stock with flux containing 3-15 wt % of dewatered borax, 0.5-3 wt % of calcium oxide and 0.4-3 wt % of quartz sand relative to the sum of weight of impurities in initial product. Melt heated to 1100-1200°C is bubbled by oxygen-bearing gas to termination of impurities oxidation. Then, oxidised melt is poured at 1200-1250°C into heated lined mould arranged at centrifuge rotor. Mould with melt is spinned at the rate creating the gravity factor Kg=50-500. Note here that used mould allows melt cooling rate not exceeding 10°C/min. Mould spinning is terminated after melt crystallisation termination to obtain casting with temperature lower that solidus temperature.
EFFECT: higher purity and good geometry of final product.
2 cl, 2 tbl
The invention relates to metallurgy, in particular to methods pyrometallurgical processing of materials containing precious metals or their alloys.
Currently, the raw materials used by the enterprises for processing of precious metals, has a great variety. Along with the technologies for processing of placer gold and receive the precious metals from the gravitational concentrators there are a large variety of industrial sources of gold-bearing raw materials. Gravity concentrates are ore breed that otdovat during the concentration of placer gold. Together with the breed otdyvautsya tiny particles of gold, the surface is covered by water films of oxides, sulphides of silver, etc. that interfere with the extraction of precious metals common Royal-vodka method. Gravity concentrates usually contain up to Au 10, Ag-20, Si-40, S 30, Fe 30, Cu-5, K 5. They also contain Ti, Pl, Mn, and other Anthropogenic sources are mainly waste jewelry alloys, gold-bearing materials received for disposal of electronic products industry, and scrap jewelry industry, containing large amounts of impurities, including iron, copper, Nickel, lead, zinc, etc. in Addition to the contamination of the alloy these impurities due to the high affinity for oxygen increases E. what about the content in the alloy up to 0.06 wt.%, which negatively affects the mechanical properties of the alloy decreases strength, elongation, ductility, increases the propensity to display dircetory etc. these examples show that the practice of extracting gold from gold-bearing materials and bringing the final product to the desired condition requires high technology adaptation to each specific version of the raw materials used. To meet these technological challenges, the industry has a large Arsenal of hydrometallurgical and pyrometallurgical technologies.
Famous classical refining of precious metals, including complete dissolution, separate deposition from solutions, the melting of pure metals, and then the subsequent soldering of components in the alloy (see, for example,). The method allows to get conditioned by impurities alloys, but requires substantial economic costs and long processing cycle up to 3 months. In addition, the dissolution of noble metals is carried out in concentrated acids, which makes the method is environmentally dirty.
Known refining of precious metals by the chlorination of remelting by blowing through the melt chlorine (see, for example, RU 2048554 C1, publ. 20.11.1995). Chlorination is used to separate the base metals of the alloy, but can be used for full and is of finara with the translation of the noble metal chlorides. The composition of the alloy are removed sequentially zinc, lead, iron, copper. But how haidoushki can be applied when significant costs associated with environmental activities, as chlorine poisoning the atmosphere of the shop. In addition, the chlorination process and lost a large number of chloride of gold. Refining the chlorination involves an additional manufacturing operation - separation and processing of chlorides for the selection of these noble metals.
The closest to the invention is a method of refining silver-gold alloys from selenium, tellurium, copper and lead. The method includes melting the original alloy, the blowing of the obtained melt air. When the melting of the source alloy to it add the intermediate processing facilities at the silver oxide in an amount of from 20 to 150% by weight of the original alloy. Then spend the separation of slag from the surface of the melt and the melt processing of carbon-containing reducing agent to remove dissolved oxygen. After removal of oxygen are pouring the melt into ingots and use them as anodes in electrolytic production of refined silver (see EN 2048554 C1, publ. 20.04.2010). When the melt blowing air metals contained in the silver, turn into oxides, which are then separated by density is of atalla and oxides. The disadvantage of this method is that it does not provide for the deoxidation of the melt and the oxygen content in profilirovannomu metal remains above acceptable level, which reduces the mechanical properties of the alloy.
However, also inherent to each method of processing material weaknesses, there are common disadvantages for all given as examples in this application, as well as other well-known technologies of processing of precious metals. All known methods are not practically solved technologically acceptable level the following tasks.
1. The release of the final product from residual intermetallic compounds, and other pollutants inclusions in a single technological process. The presence of such inclusions is unacceptable, in particular in the production of fouls and microwire in the electronics industry.
2. Giving the final product the necessary geometrical parameters usually requires a separate process of casting into ingots.
The task to be solved by the invention, is the elimination of most of the known shortcomings of the existing methods of processing of precious metals and alloys.
The technical result achieved by the proposed method, is to increase the purity of gold material from impurities while providing the attachment of the required geometric parameters of the final product.
The technical result is achieved by a method for processing gold-bearing inorganic materials, including fusion of raw materials with flux, comprising 3-15 wt.% dehydrated borax, 0.5 to 3 wt.% of calcium oxide and 0.4-3 wt.% quartz sand relative to the sum of the masses of impurities in the original product, and the bubbling of the obtained melt is heated up to 1100-1200°C, oxygen-containing gas prior to the completion of oxidation of the impurities, after which pour the melt into a heated lined mold installed in the centrifuge rotor, ensuring the temperature of the melt 1200-1250°C, rotating the mold with the melt with the speed that creates the gravitational coefficient Kg=50÷500, using the mold, providing the cooling rate of the filled melt no more than 10°C/min, the rotation of the mold is carried out until the completion of the crystallization process and lowering the temperature of the casting below the solidus temperature.
In addition, heating of the mold before pouring it melt preferably be done by pouring it melt flux, taken in an amount of 1 wt.% in relation to the weight of the oxidized melt and consisting of dehydrated borax and calcium oxide at a mass ratio of the components 3 to 1.
The proposed method pyrometallurgical processing of gold-containing inorganic materials, including the I recycle scrap jewelry and refining of gold, consists of two stages.
In the first phase, including the melting of the source material with flux or without bubbling the melt at a temperature of 1100-1200°C oxygen-containing gas, the result is oxidized melt consisting of noble metals and different amounts of oxides of related impurities. In addition, the melt can be various kinds of non-metallic impurities (not associated with slag of various intermetallic compounds), fragments linings, etc. In the second stage, carry out the separation processing of the melt in the presence of flux in the force field of the centrifuge gravity coefficient Kg in the range from 50 to 500 in the process of crystallization at the temperature of the beginning of the process 1200-1250°C (gravitational coefficient Kg is a dimensionless quantity that indicates how many times the value of the acceleration generated by the centrifuge, more free-fall acceleration on the surface of the earth, g=9.8 m/s2).
The method has a certain versatility and allows by adjustment of the composition of the charge and composition of the oxidizing gas in the first stage and changes of thermodynamic characteristics and values of the gravitational coefficient of the field of centrifugal forces centrifuges at the second stage of processing or refining to obtain a high degree of extraction of useful and refining of the melt from primase is with the enhancement of the mechanical properties of the alloy of noble metals.
The essence of the process of oxidation of the melt by bubbling oxygen-containing gas consists in the following. Zinc, having a high partial pressure at the temperature of the process 1100-1200°C, transferred in the form of metal in the gas phase and when creating oxidative environment in further forms a stable zinc oxide ZnO. Purification from admixtures noble alloy has the following mechanism: the transition into the gas phase metal zinc and the further oxidation to ZnO; the formation of condensed oxide b and the transition from condensed to a gaseous state; the formation of stable condensed oxides of Nickel and iron and their transition into the slag.
All this happens against the background of increasing oxygen content, the maximum content can reach 0.3% due to the process of dissolution of cuprous oxide in liquid copper. This amount of oxygen at 1100-1200°C provides almost complete oxidation of all impurity elements.
Borax, which is part of the slag-forming flux, is used as the fusible neutral flux with high extracting ability in relation to the oxide base elements of the system Na2O D2O3CaO - SiO2MenOmwhere Me=Fe, Mg, Ti, Zr, Al, usually occurring in various gold original products.
Quartz sand binds the oxides of W is found in low-melting silicate complexes.
Calcium oxide is used as a slag-forming flux, which increases the interfacial tension at the boundary of the slag - metal.
In the second stage, the oxidized melt is heated to a temperature of 1200°C, poured into a prepared mold special casting machine, which is a centrifuge, on the rotor where installed lined the mold. Lining moulds or heated to provide the cooling rate is flooded melt no more than 10°C per minute. Preparation of the mold for receiving the melt is in the promotion of a centrifuge rotor together with the mold to set the speed at which a field of centrifugal forces from the gravitational coefficient of from 50 to 500. Heating of the lining of the mold is carried out by pouring into a rotating mold melt borax with calcium oxide in the amount of 1 wt.% the mass of the oxidized melt the mass ratio of borax and calcium oxide 3:1. Calcium oxide, which is part of the slag-forming flux, increases the interfacial tension at the boundary of the slag/metal, contributing to the coalescence of small droplets of metals and more effective to oust them from the slag zone during processing in the centrifuge. After filling prepared in the first phase of the alloy into a rotating mold, the melt fills 2/3 part of the radius of the mold, and begins the process of centrifugal separation of the melt. If e is ω metal component of the melt is displaced by centrifugal forces centrifuges to the external radius of the mold, while the lighter weight of the sludge occupy a region of the volume of the mold is closer to the axis of rotation. The process of centrifugal separation continues until, while cooling the melt reaches the area of the external radius of the temperature of crystallization of the melt and until, respectively, the gradient of the pressure distribution along the radius of the rotating mold will not start the movement of the planar solidification front from the outer radius in the direction of the axis of rotation. Flat crystallization front supersedes all inclusions, not demanded by the process of crystallization of the alloy, in the direction of the axis of rotation, i.e. in the slag zone. Then the machine continues the rotation of the rotor from the mold without changing speed to achieve by casting the solidus temperature. The cooling rate is flooded melt no more than 10°C per minute support to no time to start the natural process of bulk crystallization of the melt until the end of crystallization. After that, the rotation of the centrifuge rotor stops, the casting is cooled and removed. After removing the casting mechanically separate the ingot or ingots of precious metals and slag formation. The geometry of the obtained ingot is determined by the structure forming part of the mold.
Laboratory testing of the proposed method was carried out as about what atom. 1000-gram sample of the waste jewelry alloys containing gold, silver, copper and contaminated by impurities of iron 0.07 wt.%, Nickel 0.06 wt.%, lead to 0.04 wt.%, zinc 0.10 wt.%, melted in a crucible in an induction installation with the addition to the melt 0.15 g of dehydrated borax, 0.03 g of calcium oxide and 0.01 g of quartz sand.. After reaching a temperature of 1100°C was started bubbling through the melt of air with a flow rate of 0.95 l/min (with conversion to normal conditions). Made 4 selection Oneida samples for analysis on the content of impurities of oxygen and major components. Bubbling was carried out for 28 min with a constant temperature of the melt is equal to 1150-1200°C. the Content of impurities was reduced and at the same time there was an increase in oxygen content (0.06 wt.%), the minimum content of impurities. Table 1 shows the results of analysis of samples of the melt collected in the course of ozonation.
|No. of selection||The processing time min||The content of impurities, wt.%|
Then the melt temperature was brought up to 1200°C and poured melt-in is installed on the rotor of the centrifuge mold. Before pouring the prepared melt in the mold it was filled with 40 grams of molten flux consisting of borax and calcium oxide in a ratio of 3:1, prepared in a separate crucible furnaces, and brought the value of revolutions of the rotor from the mold to 1600 rpm, this laboratory centrifuges corresponds to the gravitational coefficient Kg=200. Thermode licencie characteristics moulds centrifuge units determine the lifetime of the melt by pouring it with an initial temperature of 1200°C before the beginning of the crystallization process within 5-7 minutes. After completion of the process of centrifugal separation of the melt (5-6 minutes) and going through the process of directional solidification of the alloy from the periphery of the mold to its center (30-50 seconds) rotation of the centrifuge rotor has stopped. After cooling the casting (30-60 min), the casting was removed. The Central part of the ring casting mechanically separated. Then cut it in the laboratory template. The results of the study of the samples are presented in table 2. Analysis of the results of laboratory work convincingly confirm the efficiency of the proposed method and its applicability in practice.
Table 2 presents the results of laboratory testing of the method on the example of refining low-grade raw materials to produce high-grade gold for jewelry, electronics and dentistry. It shows the values of the content of impurities in the resulting casting.
|Kg||The content of impurities, wt.%|
Similar experiments were performed with other compounds of the mixture in the stated intervals of component contents, and similar results were obtained with close impurities from the resulting castings.
In comparison with the known proposed method has the following advantages:
- high technological flexibility to the composition of raw materials;
- achieved a higher degree of removal of impurities and the quality of the finished alloy;
- reduced the amount of the deadweight losses of noble metals;
- allows you to get the finished casting the final product with the given weight and geometrical parameters;
- casting the final product is free from non-metallic inclusions of any nature;
- environmental improvement of the enterprise by eliminating fumes of nitrogen oxides, hydrochloric acid, and T. p.
The sequence of operations of the proposed method in combination with the mode of operations provides them with the necessary interrelation and mutual influence, thus achieving a higher degree of purification of the melt from impurities, the higher the extraction of noble metals, the removal of the post is the enclosing non-metallic and intermetallic inclusions, the enhancement of the mechanical properties of hard alloys of precious metals, the final bars of the given geometry, as well as high process performance and environmental friendliness.
1. The method of refining gold inorganic materials, including their melting flux, containing dehydrated borax, calcium oxide and silica sand in the following components of the flux relative to the weight of impurities in the gold-bearing inorganic materials: dehydrated borax 3-15 wt.%, calcium oxide is 0.5-3 wt.%, quartz sand 0.4 to 3 wt.%, and the bubbling of the obtained melt is heated up to 1100-1200°C, oxygen-containing gas to complete the oxidation of the impurities, after which pour the oxidized melt in a heated lined mold installed in the centrifuge rotor, ensuring the temperature of the melt 1200-1250°C, carry out the rotation of the mold with the melt with the speed that creates the gravitational coefficient Kg=50÷500, using the mold, providing the cooling rate of the filled melt no more than 10°C/min, the rotation of the mold is stopped at the completion of solidification of the melt with obtaining castings of gold with a temperature below the solidus temperature.
2. The method according to claim 1, characterized in that the heating of the mold prior to pouring of the melt is carried out by pouring in pereprava flux, taken in an amount of 1 wt.% in relation to the weight of the oxidized melt and consisting of dehydrated borax and calcium oxide at a mass ratio of the components 3 to 1.
SUBSTANCE: starting material is premixed with calcium oxide in amount of 15-20 wt % of starting material and fused to obtain matte-slag melt. Then, silicon-bearing collector melt if the form FS25-grade ferrosilicon to collect platinum metals and nickel. Note here that copper remains in matte. Obtained melt is subjected to ageing. Said starting material represents a nickel-pyrrhotite concentrate. Note here that silicon-bearing alloys is used in ground form.
EFFECT: higher yield, copper and nickel separation.
2 cl, 3 tbl, 4 ex
SUBSTANCE: method includes thermal processing of crushed limestone and coal with discharge of gaseous products, which are applied for production of carbonic acid. Thermal processing is carried out in one reactor. At the first stage in the process of introduction of raw material into reactor it is subjected to heating to 1000°-1200°C by transmission of heat from constructive elements of loading canal and by exposure of raw material to plasma beam in zone of free movement of raw material particles. Thermal processing of raw material is realised in atmosphere of carbon dioxide. Further synthesis of calcium carbide is realised at temperature, at least, 1700-1800°C by induction heating of reaction mass. Obtained calcium carbide liquid is discharged. Gaseous products, from which carbon oxide and carbon dioxide are separated, are discharged from upper part of reactor, and at least, part of discharged carbon dioxide is applied for filling loading canal. For production of carbonic acid volume of carbon dioxide, remaining after filling loading canal and entire volume of carbon oxide are applied.
EFFECT: increase of target product output and reduction of process power consumption.
SUBSTANCE: tantalum-base alloy refining method involves vacuum electronic beam remelting in a horizontal crystalliser of the charge placed into it so that fumes of its metallic impurities are released on the surface that condenses them, and fumes of gas-containing impurities and production of a tantalum ingot by movement of an electronic beam from the beginning to the end of the crystalliser throughout the charge surface with its further switch-off. The charge contains metallic impurities of high-melting metals with the melting temperature close to that of tantalum. Vacuum electronic beam remelting is performed in two stages. The tantalum ingot produced at the first stage and containing impurities of high-melting metals is subject to electrochemical processing with release of tantalum-containing cathode residue that is subject to the second remelting stage so that an ingot of conditioned tantalum and fumes containing tantalum, which are returned to electrochemical processing, are obtained. From the first stage of the remelting process to the second one the specific power of an electronic beam is increased from 0.024-0.035 to 0.040-0.045 kW/mm2, and beam travel speed is decreased from 40-60 to 4-6 mm/min.
EFFECT: improving degree of extraction and purity of tantalum.
6 cl, 1 dwg, 2 tbl, 2 ex
SUBSTANCE: proposed method comprises: feeding initial alloy into cold crucible of induction furnace, forming initial alloy melt bed by induction heating in atmosphere of inert gas, continuation of induction heating and addition of the first refining agent to melt bed. Then content of at least phosphorus on impurities present in the melt bed is decreased and making the alloy ingot by hardening of the melt with decreased amount of phosphorus. Said first refining element represents the mix of metal calcium and flux containing calcium fluoride and at least one component of calcium chloride and oxide. Weight fraction of total amount of calcium chloride and oxide relative to calcium fluoride can vary from 5 wt % to 30 wt % while that of metal calcium relative to melt bed can make 0.4 wt % and higher. Alloy ingot can be produced at electron-beam furnace with cold hearth.
EFFECT: high-purity allow.
13 cl, 7 tbl, 9 dwg
SUBSTANCE: loading of metal charge and its subsequent smelting with an electron beam or plasma is performed to an upper crystalliser provided with a vertical slot, into which prior to loading of metal charge there installed is a plate from molten metal cleaned from impurities, which covers the above slot; surfacing is performed in an upper crystalliser of a molten metal bath with the depth of not more than 50 mm, without penetration of the above plate; a slot is penetrated with an electron beam or plasma in the above plate to the depth of that is less than depth of the surfaced molten metal bath by 20-30% and refined portion of molten metal is drained to the lower crystalliser for formation of an ingot. In the upper crystalliser there made is a vertical slot covered with a plate from molten metal cleaned from impurities with formation of a projection to retain heavy impurities during the melting process, and the above crystallisers are installed on a tray.
EFFECT: invention allows improving use efficiency and enlarging technical capabilities owing to reducing power consumption, shortening of a production cycle, increasing metal weight at surfacing and reducing the equipment dimensions.
5 cl, 1 tbl, 2 dwg
SUBSTANCE: method of electron-beam melting of products from high-melting metals and alloys and device for the method's implementation are proposed. The above method involves arrangement of molten material inside replaceable shape-generating melting pot and installation inside cooled vacuum chamber of cathode assembly, anode and melting pot. The latter is fixed inside anode made in the form of a metal pipe and arranged axisymmetrically inside cathode assembly with system of annular focusing electrodes and thready annular cathode. Melting of material in melting pot or first of the bottom part, and then of the whole material is performed by moving anode or cathode assembly relative to each other along their vertical axis with formation of crystallisation zone of molten product at the pot bottom and by movement of zone of molten material upwards with velocity providing the formation of shrinkage hole in upper part of the product.
EFFECT: obtaining complex products of high strength; increasing the surface area of its carrying section.
7 cl, 2 dwg, 8 ex
SUBSTANCE: method involves loading of metal charge to crystalliser and its melting with electron beam or plasma by scanning its surface so that molten metal is formed and an ingot is obtained. Either non-pressed metal charge or metal charge pressed into a briquette is used; it is re-molten by means of two-sided remelting process; at that, when briquetted metal charge is used, melting of one side is performed due to alternate movement of heating zone from one side of square to its opposite side, and when non-pressed metal charge is used, melting of one side is performed due to constant movement of heating zone from the centre along square spiral to crystalliser perimetre. At that, melting of one side is performed to the depth of larger half from height of the produced ingot; when melting process is completed on one side, the obtained ingot is turned and laid with its molten part at crystalliser bottom, and then, melting of the other half is repeated as per the same sequence according to which the melting of the first half was performed.
EFFECT: invention allows reducing power consumption, manufacturing cycle and metal weight during melting process.
2 cl, 2 dwg
SUBSTANCE: method involves loading of charge and metal melting with electron beam with electromagnetic mixing of the melt; melting is performed in a melting pot with slag lining in three-stage mode: 1-st stage - warming of the charge and making of fluid bath at electron beam power P1=K1·Pmax, where K1≤0.5; 2-nd stage - averaging and purification of metal at electromagnetic mixing of the melt with direction of mixing towards walls of slag lining at electron beam power P2=K2·Pmax, where 0.5<K2<0.9; 3-rd stage - drain of the melt at electromagnetic mixing of the melt with direction of mixing towards the melting pot centre at electron beam power P3=K3·Pmax, where 0.9≤K3≤1, where P1; P2 and P3 - beam power at stages 1, 2 and 3 of the mode; K1, K2 and K3 - beam power coefficients; Pmax - maximum electron beam power.
EFFECT: invention allows stabilising the melting mode owing to excluding breakdowns of electron beam gun, increasing the uniform distribution of impurities as per the volume of ingots and reducing specific electric power costs.
SUBSTANCE: proposed method comprises feeding power for smelting, feeding working gas via flow channel 8 and directing it by at least of plasma burner 10. Plasma is generated by at least one induction heating coil 18 enveloping said flow channel 8 to form heating zone 17. Proposed furnace comprises at least one heater 6 to supply smelting power. Said heater 6 comprises tubular case 7 that cover flow channel 8. Lengthwise section of tubular case 7 is made similarly to plasma burner 10. Note here it has at last one induction heating coil 18 enveloping said flow channel 8 to form heating zone 17.
EFFECT: lower costs.
27 cl, 3 dwg
SUBSTANCE: procedure consists in loading charge of various composition and dimension into melting installation, in melting with flare of plasmatron or electron beam producing melt of metal, and in correction of melting process with consideration of parametres change. Surface of melts is thermo-graph scanned in infra-red range of heat radiation with determination of temperature field and thermal image recording. At local changes of the range of temperature field in the direction of temperature decrease, when charge is melted not completely, temperature of melt surface is equalised by correction of trajectory of plasmatron flare transfer of electron beam directing it on sections of surface with reduced temperature.
EFFECT: stabilisation of melt temperature and maintenance of maximal area of melt surface on cold bottom.
3 cl, 1 dwg, 2 ex
SUBSTANCE: invention relates to concentration of minerals and can be used for extraction of fine gold from argillaceous sediments. This method comprises preparation of suspension of argillaceous sediments, trapping of fine gold from said suspension by introduction of vegetable material-based sorbent premixed to 0.3 mm grain size in suspension and mixing. Then, sorbent is flushed through 0.3 mm mesh screen, dried and subjected to assay fusion. Note here that suspension is prepared at S:L ratio of 1:25. Sorbent is added to suspension activated in mixer to homogeneous state for 3-5 minutes and, then, mixed for 30-40 seconds. After sorption, loose flakes bearing gold are flushed.
EFFECT: higher yield, environmental safety.
SUBSTANCE: method includes oxidising roasting, percolation leaching of the roasted product with aqueous solution of an oxidising agent or mixtures of oxidising agents to obtain a rhenium-containing solution and an insoluble residue, sorption of rhenium from the rhenium-containing solution in a separate apparatus, drying the insoluble residue, mixing with fluxing agents and fusion on a metal collector. Percolation leaching is carried out at redox potential values of 900-1100 mV and temperature of 50-90°C, with simultaneous sorption of rhenium, followed by desorption and separation of rhenium compounds or rhenium metal from the strippant. The fluxing agents used to fuse the insoluble residue are fluorspar, sodium carbonate and sodium nitrate. Fusion is carried out at temperature of 1200-1800°C on a metal collector in several steps, while discharging the formed slag after each step and fusing the next portion of the mixture on the collector from the previous fusion with separation of the alloy of platinum metals with the collector.
EFFECT: high degree of extraction of rhenium, low reactant consumption, labour input, faster processing of the material, considerable reduction of the volume of solutions which require recycling.
8 cl, 1 dwg, 1 ex
SUBSTANCE: method includes passing the solution through polymer fibre for sorption of silver ions. After passing the solution, silver ions contained in the fibre are reduced to a metal state with 0.02 M aqueous solution of a mixture of ascorbic acid with glucose in ratio of 1:9. Silver metal is then extracted by burning the silver-containing fibre in an air atmosphere at temperature of 450-500°C, followed by washing the formed silver reguli.
EFFECT: recovering silver ions from industrial waste water, improved method of extracting silver from process solutions used when producing textile materials with antimicrobial properties.
SUBSTANCE: invention relates to hydrometallurgy of noble metals and can be used for silver extraction from alkaline cyanide solutions by cementation. Proposed method comprises cementation by aluminium as 0.1-2.0 mm thick chips. Cementation is carried out at specific solution feed rate of 1-4 m3/m2·h at concentration of sodium hydroxide of 1.0-10.0 g/l.
EFFECT: higher yield and quality.
3 tbl, 3 ex
SUBSTANCE: electronic waste is crushed on a hammer crusher; crushed copper is added, and then, it is fused in presence of flux during 45-60 minutes at the temperature of 1320-1350°C with air blowdown at its flow rate of 3-4.5 l/h and the obtained slag containing at least 2.6 wt % of precious metals is separated from slag.
EFFECT: effective electronic waste processing with increase of content of precious metals in an alloy.
SUBSTANCE: invention relates to hydrometallurgy and can be used for processing of concentrates, industrial products and solid wastes containing metals. Proposed process comprises leaching of cake 3 n, by HCl solution at 70°C and L:S ratio of 2. Note here that leaching is performed in the presence of table salt of concentration making at least 120-140 g/dm3.
EFFECT: intensified leaching, higher yield.
4 tbl, 2 ex
SUBSTANCE: method to process an alloy of ligature gold, containing not more than 13% of silver and at least 85% of gold, includes electrolysis with soluble anodes from initial alloy with usage of hydrochloric acid solution of aurichlorohydric acid (HAuCl4) with excessive acidity by HCl 70-150 g/l as electrolyte. Electrolysis is carried out with deposition of pure gold on cathodes. At the same time into the initial electrolyte prior to start of the electrolysis process they introduce nitric acid to its concentration in electrolyte 70÷100 g/l. Then nitric acid is added in process of electrolysis into electrolyte in a dosing manner.
EFFECT: performance of gold refining per one stage with production of target product with high content of gold with reduced duration of process and lower energy and labour inputs.
SUBSTANCE: invention relates to the technology of production of gold nanoparticles. The method of production of gold nanoparticles from the raw material containing iron and non-ferrous metals comprises preparation of the chlorazotic acid solution of gold using chlorazotic acid. Then floatation extraction of gold precursors is carried out with cationic surfactants from the solution, separation and evaporation of the organic phase to concentrate the gold precursors. Then the concentrate reduction is carried out to obtain dispersion of gold nanoparticles. At that the starting material is first treated with hydrochloric acid to form the insoluble precipitate. Production of chlorazotic acid solution is carried out by dissolving in chlorazotic acid solution of insoluble precipitate. Before floatation extraction of precursors the nitric acid is removed from chlorazotic acid solution with methyl or ethyl alcohol or hydrochloric acid.
EFFECT: improvement of efficiency of the method of production of nanoparticles, namely the increase in the number of gold nanoparticles obtained or its hybrids with noble metals.
SUBSTANCE: process can be used in hydrometallurgy for processing of gold-bearing two-fold hardness concentrates, that is, stock containing gold dispersed in sulphides and organic carbonaceous substance. Prior to feeding the concentrate acid pulp produced by pre-treatment of concentrate with acid into autoclave is cleaned of chlorides. Autoclave leaching is conducted at 225-235°C and terminated at reaching the pulp redox potential in the range of +700 - 730 mV relative to standard hydrogen electrode. For cleaning the pulp of chlorides at filter or at continuous return flow decantation hot condensate or natural water and/or desalinised water may be used. To maintain preset temperature at autoclave leaching cold fresh and/or reused water is fed to every section of autoclave.
EFFECT: higher gold yield.
4 cl, 7 dwg, 3 tbl, 2 ex
FIELD: process engineering.
SUBSTANCE: invention relates to cleaning of silver-bearing materials by hydrometallurgy processes, for example, scrap and wastes of microelectronics. Proposed method comprises dilution of silver-bearing material in nitric acid, addition of sodium nitrate to nitrate solution at mixing, extraction of silver salt precipitate and pits treatment to get metal silver. Note here that after addition of sodium nitrate the reaction mix is held for 1 hour to add sodium carbonate or bicarbonate to pulp pH of 8-10. Free silver salt precipitate as silver carbonate is separated from the solution by filtration. Sodium nitrite and carbonate or bicarbonate is added in the dry form. Note here that sodium nitrite is taken with 25% excess of stoichiometry.
EFFECT: higher purity and yield, simplified process.
2 cl, 2 ex
FIELD: noble metal hydrometallurgy.
SUBSTANCE: invention relates to method for acid leaching of platinum method from secondary raw materials, in particular from ceramic support coated with platinum metal film. Target metals are leached with mixture of hydrochloric acid and alkali hypochlorite at mass ratio of OCl-/HCL = 0.22-0.25 and redox potential of 1350-1420 mV.
EFFECT: decreased leaching temperature, reduced cost, improved platinum metal yield.