Extraction of silver from alkaline cyanide solutions
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
The invention relates to the field of hydrometallurgy of precious metals and can be used, in particular, to extract silver from cyanide solutions by cementation.
Known methods of extraction of precious metals from cyanide solutions by cementation using as reagent precipitator zinc or zinc dust(1).
Zinc dust and chips in the air undergo oxidation, which complicates their use.
There is also known a method of extracting silver from cyanide solutions by cementation, in which the reagent precipitator used aluminum powder (2).
Aluminum powder consists of particles with a size of 5-20 μm, has a very developed surface, so that when in contact with air rather intensively oxidized, resulting after cementation receive precipitation containing 20-30% aluminum. Such precipitation before receiving ingots (fuse) require additional operations (alkaline or acid). In addition, in view of the difficulties associated with the wetting of the dust, need a special form of agitator. In campaign mode because of the developed surface of the aluminum dust is unacceptable dissolves quickly. In the process of campaigning because of the good contact of the solution with air, there is intense saturation of the solution with oxygen, which slows down the process of deposition, in addition, the precipitate of silver, formed by deposition of aluminum dust, then quickly dissolves (3).
The disadvantage of this method is the low velocity of the deposition of silver on the reason for the slow wettability of aluminum dust cyanide solutions. In addition, this method is associated with high consumption of aluminum resulting from unproductive dissolution of the last lye.
The task, which is aimed by the invention is the provision of improved performance of silver extraction from alkaline solutions and reducing the consumption of the precipitator.
The task is solved by the technical result, which is in the choice of optimal conditions cementation, namely due to the optimal size of the precipitator, the concentration of sodium hydroxide and the optimal flow rate of the deposition of silver.
The technical result is achieved in that in the method of extracting silver from alkaline cyanide solutions, including cementation aluminum, which is carried out with the use of aluminum in the form of chips with thickness of 0.1-2.0 mm while maintaining the concentration of sodium hydroxide 1-10 g/l to passing the solution with the specific rate of 1-4 m3/m2PM
The difference of the proposed technical solutions from the prototype is the use of aluminum the form of chips with thickness of 0.1-2.0 mm, ensuring the concentration of sodium hydroxide 1-10 g/l with a specific velocity cementation 1-4 m3/m2PM
When using aluminum shavings in the process of cementation aluminum actively interacts with alkali (NaOH) is one of the components of cyanide solutions. Upon contact of aluminum with such solutions containing silver, there are two main reactions:
the reaction cementation
the reaction of dissolution of aluminum in an aqueous solution of alkali
As you can see, the more developed the surface precipitator, the more it is spent on interaction with the alkali with hydrogen gas, causing it to unproductive consumption, i.e. this reaction is parasitic.
The method consists in the following. Chip thickness less than 0.1 mm is quickly dissolved in alkaline cyanide solutions, which leads to increased consumption of aluminum, and the use of chip thickness greater than 2.0 mm due to the smaller contact surface of the precipitant solution slows down the cementation process and decrease, as a consequence, the degree of extraction of silver.
The prior art is not identified technical solutions that have the signs consistent with the distinctive features of the present invention, therefore, can be considered that the proposed solution meets the criterion of "inventive step".
The method is illustrated by the following examples.
Example 1. The study was carried out in campaign mode with loading precipitator 15 g/l NaOH concentration of 1 g/l for 120 min with a selection of solutions for the analysis of silver for the extraction residue. The results of the experiments are shown in table 1.
|the table 1|
|The results of the deposition of silver from solutions.|
|Time, minutes||The concentration of silver in solution (mg/l) when the chip thickness (mm)|
|0,05||0,1||2,0||2,5||Al the dust|
As can be seen from table 1, the best results on the deposition of silver obtained on the aluminum flakes with thickness of 0.1-2.0 mm, while its extraction amounted to more than 99.99%, and the prototype is 75,3%.
Example 2. The study was carried out in campaign mode with a load of 15 g/l of aluminum shavings in the thickness of 1.0 mm for 120 minutes With a selection of solutions for the analysis of silver for the extraction residue. The results of the experiments are shown in table 2.
|The results of the deposition of silver from solutions of Table 2.|
|Time, minutes||The concentration of silver (mg/l) in solution at a concentration of sodium hydroxide (g/l)|
As can be seen from table 2, the best results on the deposition of silver obtained when the concentration of sodium hydroxide and 1.0-10.0 g/l, the extraction of silver amounted to more than 99.99%.
Example 3. Studies were performed in columns with a diameter of 0.05 m and a height of 0.25 m with a load of chips 150 g, the concentration of the silver solution of 920 mg/l, NaOH - 5.0 g/l and the specific rate of the transmittance of the solution is from 0.5 to 4 m3/m2h, chip thickness 1,0 mm the results of the experiments are given in table 3.
|The results of the deposition of silver from solutions (Table 3).|
|Time min||The extraction of silver in solution (%) specific velocity (m3/m2h)|
As can be seen from table 2, the best results are obtained when the specific speed transmission solution from 1 to 4 m3/m2h, thus removing 180 min amounted to 99.9%.
Sources of information
1. Metallurgy of noble metals (foreign experience). Meretukov M.A., Orlov A.M. - M.: metallurgy, 1991, pagination 126-131.
2. Metallurgy of noble metals. Malinetskii I.N., The Chugai is L.V. - Ed. Metallurgy, 1987, 182-185.
3. Metallurgy of noble metals. Textbook for high schools (Malinetskii I.N., Chugaev L.V., Borbat VF and others). Edited tchugaev L.V. - 2nd ed., revised and enlarged extra - M.: metallurgy, 1987, p.189 (prototype).
The method of extracting silver from alkaline cyanide solutions, including cementation aluminum, characterized in that the cementation is carried out with the use of aluminum in the form of chips with a thickness of 0.1-2.0 mm, while maintaining the concentration of sodium hydroxide and 1.0-10.0 g/l to passing the solution with the specific rate of 1-4 m3/m2PM
SUBSTANCE: proposed method comprises nickel carbonization by forcing nickel salt solution via powder of reduced iron. Said salt solution is forced at the rate of 0.5-1.0 ml/min. Note here that reaction mix is subjected to microwave radiation at frequency of 7.5-10.5 GHz. Said process is conducted at 20-30°C. Nickel salt solution is forced via powder of reduced iron repeatedly at simultaneous microwave radiation effects.
EFFECT: higher degree of nickel extraction.
3 cl, 3 dwg, 1 tbl
SUBSTANCE: method includes copper sedimentation by solution contact with copper-bearing clinker. Before sedimentation clinker is treated with solution containing sulphydric collector, for instance solution containing 0.5-10 g/l of xanthate, during 15-30 minutes. After treatment clinker is contacted with copper-bearing solution.
EFFECT: improving clinker sedimentary capacity, rate and degree of copper sedimentation.
1 tbl, 1 ex
SUBSTANCE: method involves treatment of rock with a sodium cyanide solution with formation of dispersion of rock particles with gold compound in the form of Na[Au(CN)2], which is dissolved in it. Then, particles are removed from the dispersion so that clarified solution of gold compound is obtained. Clarified solution contacts a solid zinc source so that their products are obtained as a result of reactions of ionic exchange and replacement in the form of water solution of zinc compound Na2[Zn(CN)4] and solid phase of gold. Solid phase of gold is separated and processed so that metal gold is obtained. As zinc source there used are particles of zinc hydroxide consisting of a composite sorbent dispersed in water, consisting of cellulose fibres with particles of zinc hydroxide, which are immobilised with them at their chemical deposition. Solid phase of gold is extracted in the form of its hydroxide.
EFFECT: accelerating and simplifying the process.
4 cl, 3 ex
SUBSTANCE: invention can be used for extraction, concentration and cleaning of molybdenum from companion elements (Fe3+, Cu2+, Zn2+, Ni2+, Co2+, Al3+, Sn4+, Sb3+, rare-earth elements3+, etc.) at processing of different liquid and solid molybdenum-containing wastes and middling products. Extraction method of molybdenum from diluted acid solutions containing companion elements of molybdenum involves molybdenum deposition in the form of its salt. Besides, deposition with molybdenum purification is performed in the form of its cesium salt of 12-molybdophosphoric acid containing the following: Cs3-xHxPMo12O40·nH2O (x=0-1, n=9-12). Deposition is performed at heating up to 40-80°C by subsequent addition of orthophosphate-ion in the form of soluble phosphate or orthophosphoric acid, strong acid, for example sulphuric acid or sodium hydroxide up to pH 1-3 and soluble cesium salt, including mother solutions obtained during leaching of pollucite.
EFFECT: increasing extraction degree of molybdenum from process and effluent solutions.
2 dwg, 3 ex
SUBSTANCE: reduction is performed with hydrogen generated in solution; at that, reduction is catalysed with reduced metal itself, which is contained in finely dispersed state. Reduction process is performed in multi-pass reactor at variable pressure that is changed with frequency of 1-5 Hz from maximum to minimum values of 8 kg/cm2 to 0.25 kg/cm2. Extraction plant of metals capable of hydrogen absorption from solutions includes dosing device, modified displacement pump, electrolyser for hydrogen generation and multi-pass reactor in the form of labyrinth.
EFFECT: simplifying the process and improving the purity of extracted metal.
10 cl, 9 dwg, 8 tbl, 4 ex
SUBSTANCE: procedure for treatment zinc containing gold-silver and/or silver-gold cakes consists of sulphuric acid leaching with aeration by air or mixture of gases oxygen-air and in filtration of pulp with production of filtrate containing compounds of zinc, copper and selenium. Selenium is cemented from filtrate with metallic copper. Pulp is filtered and there is produced copper containing selenium cake and the second filtrate. At pH 1.0÷3.0 copper is cemented from the second filtrate with addition of at least one equivalent of metallic zinc. Upon total dissolution of zinc pulp is filtered and there is produced copper containing cake and the third filtrate containing sulphate of zinc. The third filtrate is electrolysed; there is produced cathode zinc. Spent electrolyte is returned to leaching zinc containing gold-silver and/or silver/gold cake.
EFFECT: reduced consumption of sulphuric acid and water at processing zinc containing silver-gold cyanic cakes into commodity silver-gold alloy, metal zinc, metal copper and selenium-cooper product.
16 cl, 1 tbl
SUBSTANCE: here are disclosed 2 versions of fabrication of high porous silver sponge where as source of silver there are used silver salts or silver alloys successively converted into salts. The versions of the procedure consist in preparing concentrated chloride solution whereat silver salt is dissolved in accordance with its solubility at temperature of solution boiling. Salt of polyvalent metal of lead chloride at amount equal to amount of dissolved silver is introduced into prepared solution. Further, silver-lead sponge is settled with zinc. Contaminating substances and lead are removed from settled sponge which is successively washed and dried.
EFFECT: accelerated production of silver sponge due to reduced time for its sedimentation; qualitative stable high porosity of produced silver sponge.
2 cl, 1 dwg, 1 tbl, 3 ex
SUBSTANCE: procedure consists in settling silver with addition of zinc powder. Before sedimentation of silver zinc powder is preliminary activated in 1-5 % solution of HCl at temperature 80-100°C. Lead chloride at amount of 2-15 g/dm3 is added into chloride solution before sedimentation. The procedure of sedimentation consists in adding activated zinc powder to chloride solution heated to 50-60°C and in successive conditioning for forming a lead sponge and sedimentation of silver on it. After conditioning the formed sponge is broken and solution is mixed. Activated powder of zinc is added in big portions.
EFFECT: raised efficiency of chloride solution purification, increased output of silver, reduced consumption of zinc and time of sedimentation, and thereby reduced cost of process.
2 cl, 1 tbl, 3 ex
SUBSTANCE: inventions relate to gold extraction from solutions with low concentration at presence of ions of other metals, for instance cleaning solutions of gold-extracting plants, brines of potassium manufacturing, geothermal water, water of brine lakes and salt water. Essence consists in that through powder of metal-restorative it is passed gold-containing solution with low concentration at presence of ions of other metals during 2-240 hours. In the capacity of metal-restorative it is used lead-plated zinc powder of grade +0.001 mm - 2 mm with lead content 1-90 wt %. or powders of metals, used at temperature of solution not less than 50°C and selected from the group: Zn, Fe, Ni, Pb, Sn, Sb, of grade +0.1 mm - 5 mm. Additionally before cementation powders are placed in cartridge. Received after cementation gold-containing concentrate is separated by means of intensive mechanical agitation, it is treated by nitric or acetic acid. Gold sediment is separated by filtration, dried and molten with fluxing additives with receiving of crude metal.
EFFECT: increase of effectiveness and selectivity of gold extraction from solutions with low concentration.
3 cl, 1 dwg, 3 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: 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: process engineering.
SUBSTANCE: method comprises electrical treatment of minced material pulp in chloride solution and extraction of commercial metals. Both stages are executed in reactor using at least one membrane-free electrolytic cell. At electrical treatment, minced stock pump with S:L ratio equal to 1:(1-20) in chloride solution with chlorine concentration of 60-180 g/l to be acidified to pH 0.2-1.0. At electrical treatment initial stage, pump is mixed at current bulk density of 1000-10000 A/m3 at electrolytic cell permanent voltage of 2-5 V. Termination of pulp electrical treatment is fixed by transition over peak of time dependence of current magnitude and reach of pH 1-2.Treated pulp is fed to the stage of commercial metal extraction. For this cathode current density is set to 50-200 A/m3. Extraction is considered terminated at pH 3-7. Thereafter, cathode residues of both said stages are combined and directed for metal production by known processes.
EFFECT: incidental extraction directly in electrical chlorination of ore pulp.
11 cl 3 dwg, 1 tbl
SUBSTANCE: in preparation of mineral mass for leaching carbonate-alkaline solution is added thereto which contains diluted carbonic acid and active oxygen. Said carbonic acid and active oxygen are produced by electrochemical and/or photochemical treatment of soda solution. Besides, complexing agent and ion-exchange gold-selective resin with active oxidiser radicals and complexing ions for gold are added thereto. Note here that concentration of complexing agents in said resin is maintained larger than that in solution to process mineral mass. Then, prepared mineral mass is placed in tray with moisture proof sides and bottom and cured under moisture-proof film for sorption leaching of gold from sintered material. Note here that leaching is carried out under penetration-diffusion conditions. Then, oxygenated water or weak solution of the main complexing agent to obtain the pulp. Then, said pulp is bubbled to separate saturated sorbent therefrom.
EFFECT: higher efficiency of gold extraction.
2 cl, 1 dwg, 1 ex
SUBSTANCE: extraction method of precious metals from solutions involves contact of a solution with a sorbent applied onto a carrier with developed surface. Xanthogenate of non-precious metals, which is applied onto the carrier, is used as a sorbent. A filtering flexible plate material is used as a carrier. Filtering flexible plate material with the applied sorbent is rolled into a coil that is placed into a sorption column and contact is performed by passing initial solution through the coil.
EFFECT: improving selectivity of extraction and content of precious metals in a product by using available reagents and materials.
2 cl, 1 tbl, 1 ex
SUBSTANCE: dilution of tin solder is performed with 5-20% solution of methanesulfonic acid with oxidiser additives at the temperature of 70-90°C during two hours. Then, plastic mass is removed, and flushed and supplied for further utilisation. After that, suspended and frameless parts, microcircuits are separated on a grid, cleaned from methanesulfonic acid solution, dried, crushed to the particle size of -0.5 mm, separated on a magnetic separator into two fractions and processed fraction by fraction by means of hydrometallurgical methods. Besides, magnetic fraction is processed by means of an iodine-iodide method, and non-magnetic fraction is processed by means of a nitrohydrochloric acid method. The rest suspension of metastannic acid in solution of methanesulfonic acid with gold and lead impurities are coagulated at boiling during 30-40 minutes and filtered. Filtered deposit is flushed with hot water, dried and annealed till gold-bearing stannic oxide with further removal of gold from it is obtained.
EFFECT: reduction of reagent consumptions, losses of gold together with stannum and lead, reduction of power consumption and losses of palladium and platinum.
6 cl, 1 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.