RU2267544C1 - Method for extracting of precious metals from solutions by sorption - Google Patents

Abstract

FIELD: precious metallurgy, in particular, methods for extraction and concentration of precious metals used on processing of weak process solutions and pulps containing gold, silver and platinum-group metals.

SUBSTANCE: method involves providing contacting of solutions containing small amounts of precious metals with sorbent preliminarily treated with solution of derivatives of dithiocarbonic acid O-ethers. Insoluble porous substances such as activated coal, lignin, synthetic sorbent, etc may be used as basic sorbents. Acidity value of solution used in treatment process may range from 2 to 11, preferably from 5 to 8. Sorbent is preliminarily treated at room temperature for 2-24 hours.

EFFECT: increased efficiency of sorbent, increased extent of extraction and rate of process for extraction of metals from solutions.

3 cl, 6 tbl, 6 ex

Description

The invention relates to the metallurgy of precious metals, in particular to methods for their extraction and concentration, and can be used in the processing of poor technological solutions and pulps containing gold, silver and platinum group metals.

Known methods for the extraction of precious metals from solutions by electrolysis, cementation and sedimentation in the form of sparingly soluble compounds. All these methods are applicable only under certain conditions, limited by the concentrations of the extracted component, as well as the acid-salt composition of the solution. At low concentrations of recoverable metal, these methods do not provide the required degree of extraction and, as a result, are associated with a large consumption of reagents or electricity. In particular, when extracting gold from cyanide solutions, metal zinc cementation is used / (1) Maslenitsky I.N., Chugaev L.V. and others. Metallurgy of precious metals. - M .: Metallurgy, 1981 /, while the consumption of zinc is 15-50 g / t of solutions, and the concentration of metal in an anhydrous solution is 0.02-0.03 mg / l. Gold is extracted from thiourea solutions by electrolysis, while the degree of its extraction is even less. Known methods for the extraction of metals from poor solutions by sorption (1), which consist in contacting the processed solutions with synthetic or natural porous substances. To extract gold and silver, in particular, activated carbons are used, some natural substances are lignin / Voiloshnikov G.I., Chernov V.K. et al. Study of the possibility of using carbon lignin-based sorbents for the extraction of noble metals from cyanide solutions. University News. Color metallurgy. 1982, No. 5, pp. 52-55 /, as well as synthetic ion-exchange sorbents. for example, anion exchange resin AM-2B (1). The main advantage of sorption is the simplicity of the method, combined with a sufficiently high degree of extraction and a low residual concentration of gold, which may not exceed 0.01 mg / L. To increase capacity, selectivity, and improve other functional properties, sorbents are preliminarily processed using special reagents. For example, when silver is extracted from solutions, the pyrocatechol polymer is subjected to preliminary sulfidation / A.s. USSR No. 1678873. - 1991. A method of extracting silver from solutions.

The closest in technical essence is a method for extracting silver from fixed solutions with activated carbon (US patent No. 4394354, 1983). The method of removing silver with impregnated halogen activated carbon), including preliminary contacting the coal with a solution containing halides - iodine or bromine, until their content in coal is 0.1-50% and then passing the fixative solution through a column with modified carbon until the breakthrough. "

The main disadvantage of this method, selected by the prototype, is the limited use, expressed, in particular, in that it can be used only for some silver-containing solutions. In addition, to achieve the required degree of silver recovery, the consumption of expensive reagents is very high and reaches 50% by weight of coal. And finally, the prototype is not applicable for the processing of more widespread technological solutions, in particular cyanide, thiourea, etc.

The present invention is aimed at eliminating these disadvantages and aims to increase the capacity of the sorbent, the degree of extraction and intensification of the process of extraction of metals from solutions.

The specified technical result is achieved by the fact that when the precious metals are extracted from solutions by sorption, which includes pretreatment of the sorbent with a reagent and contacting the solution with the treated sorbent, the pretreatment of the sorbent is carried out using an aqueous solution of dithiological acid derivatives of O-esters as a reagent.

The essence of the invention lies in the fact that chloride, cyanide, thiosulfate and other solutions containing trace amounts of noble metals (gold, silver, platinum, and / or palladium) are brought into contact with a sorbent, a pre-treated solution of derivatives of dithiofaric acid O-esters . Insoluble porous substances, for example, activated carbon, lignin, synthetic sorbent, etc., are used as the initial sorbent. The selected carrier sorbent is pretreated with an aqueous solution of potassium salts of d-ethyl acid or O-butyl ether of cellulose xanthate or sodium xanthate. The concentration of these compounds in the processing solution is from 0.01 g / DM ³ to the concentration of maximum saturation for the selected reagent. The pH of the treatment solution should be from 2 to 11, preferably 5-8. The duration of the preliminary treatment of the sorbent at room temperature is 2-24 hours. This treatment allows you to give the sorbents a higher capacity and selectivity with respect to noble metals in complexing media.

Contacting the pre-treated sorbent with a solution containing noble metals is carried out until a full or predetermined degree of extraction of the target component is achieved. The saturated sorbent is separated from the mother liquor and processed by known methods (desorption, thermal decomposition) to obtain a concentrate or other marketable product - a compound, a metal.

The implementation of the proposed method is discussed in the following examples.

Example 1. Weighed portions of lignin and activated charcoal AP-B, each weighing 1 g, were pretreated with 25 ml of a 10 g / L solution of d - dihydric acid ethyl ethyl ester for 2-5 hours, washed with water and brought into contact with a model gold chloride or 100 ml thiosulfate silver-containing solution for 24 hours. By changing the concentration of gold and silver in the solution after sorption, the capacity and the degree of their extraction were calculated. During sorption and according to the final results, the capacity of the modified sorbent, the deposition rate of metals, and the degree of extraction from solutions were evaluated by a known method. The results of the experiments are shown in table 1. For comparison, experiments were carried out using untreated pre-coal and lignin.

Example 2

Activated carbon AP-B with a mass of 100 kg was pre-treated with 200 l of a solution of 20 g / l of dithiofluoric acid O-butyl ester for 24 hours, washed with 300 l of water, and then brought into contact with a real gold-containing solution in a sorption column the following composition: 500 mg / dm ³ dissolved chloride salts, 150 μg / dm ³ gold, 300 μg / dm ³ mercury, the amount of non-ferrous metals - not more than 100 mg / dm ³ , pH = 5.5; the solution was obtained by underground leaching of gold. The results of the sorption of gold on the starting coal and the treated coal are shown in table 2.

Example 3

Weighed portions of activated charcoal AR-B and ion exchanger AB-17 weighing 5 g each were treated with a solution of dithio-carbonic acid O-butyl ester with a concentration of 20 g / l for 10 hours, washed with water and brought into contact with a chloride solution of refining production of the composition, g / dm ³ : Pt-0.619; Cu-72.1; Sn-11.38; Zn-4.53; Pb-2.5; Al-0.48; HCl-120 for 24 hours. The platinum concentration was determined by the platinum sorption capacity and its degree of extraction. For comparison, experiments were carried out using untreated coal and anion exchange resin. The results are shown in table 3.

Table 1
The results of experiments on the extraction of gold and silver by modified sorbents Sorbent Modifying reagent, concentration, g / dm ³ Duration of modification, hour The composition of the test solution Capacity mg / g The residual concentration, mg / DM ³ The degree of extraction,% Lignin Potassium butyl xanthate 10 2 HCl-1 g / dm ³
Au ³⁺ -0.2 mg / dm ³ 6.5 0,025 87.5 5 HCl-1 g / dm ³
Au ³⁺ -0.2 mg / dm ³ 7.4 0.009 95.5 2 Na ₂ S ₂ O ₃ -200 g / dm ³
Ag ⁺ -3 g / dm ³ 38 370 87 5 Na ₂ S ₂ O ₃ -200 g / dm ³
Ag ⁺ -3 g / dm ³ 40 160 94.7 Lignin source HCl - 1 g / dm ³
Au ³⁺ - 0.2 mg / dm ³ 1,2 0.12 40 Na ₂ S ₂ O ₃ -200 g / dm ³
Ag ⁺ -3 g / dm ³ 3.0 1020 61 Activated carbon AR-B Potassium butyl xanthate-10 2 HCl-1 g / dm ³
Au ³⁺ -0.2 mg / dm ³ 69 0.007 96.5 5 HCl-1 g / dm ³
Au ³⁺ -0.2 mg / dm ³ 76 0.005 97.5 2 Na ₂ S ₂ O ₃ -200 g / dm ³
Ag ⁴⁺ -3 g / dm ³ 115 63 97.9 5 Na ₂ S ₂ O ₃ -200 g / dm ³
Ag ⁺ -3 g / dm ³ 132 22 99.3 Activated carbon AR-B source HCl-1 g / dm ³
Au ³⁺ -0.2 mg / dm ³ 39 0,033 89 Na ₂ S ₂ O ₃ -200 g / dm ³
Ag ⁺ -3 g / dm ³ 52 230 93

Example 4. It is characterized in that instead of activated carbon, lignin was used and sorption extraction of iridium was carried out from similar refining solutions containing 40 mg / dm ^{3 of} iridium. The results are shown in table 4.

table 2
Results of gold sorption from underground leaching solutions Sorbent The gold content in the initial solution, μg / DM ³ The gold content in the solution after sorption, μg / DM ³ The equilibrium capacity of coal in gold,% The degree of extraction,% Source coal 150 twenty 0.25 85 Pre-treated coal 150 3 0.37 98

Table 3
The results of experiments on the sorption of platinum Sorbent Platinum The residual content, mg / DM ³ Extract% SOYE, mg / g Activated carbon AR-B processed 58.8 90.5 25.3 source 208 67 14.3 Processed lignin processed 402 42 11.6 source 597 four 0.8 ANKB 35 processed 394.8 42.9 11.9 source 274.4 60.3 13,4 AB-17 (gel) processed 140,4 79.7 22.1 source 52 92.5 12.8

Table 4
Results of sorption of iridium Sorbent Iridium The residual content, mg / DM ³ Recovery% SOYE, mg / g Activated Carbon AR-B processed 5.5 83 fifteen source 32,4 twenty 1.3 Lignin modified processed 23.9 41 1,2 source 38.5 four 0.1 AB-17 (gel) processed 4.9 87 19 source 33,2 eighteen 1,1

Example 5. It is characterized in that the extraction of palladium from the mother liquors of the refining production was carried out with charcoal and lignin treated with pre-butyl ether of dithiofluoric acid. Cellulose and sodium cellulose xanthate were also used. The composition of the initial solution, the sorption capacity for palladium and the degree of its extraction are shown in table 5. The remaining experimental conditions are similar to examples 3 and 4.

Table 5 Metal Ref. Conc. mg / dm ³ Cellulose Cellulose Xanthate Lignin Processed lignin Coal Processed coal Ost. soda mg / l Ex. % SOYE mg / g Ost. soda mg / l % SOYE mg / g Ost. soda mg / l Ex. % SOYE mg / g Ost. soda mg / l Ex. % SOYE mg / g Ost. soda mg / l Ex. % SOYE mg / g Ost. soda mg / l Ex. % SOYE mg / g Pd 567 370 34 four 27 95 10.5 510 10 one 1,03 99.8 eleven 147 74 8.4 1.16 99.7 eleven Pt 317 308 3 0.2 281 eleven 0.8 301 5 0.3 244 23 1,5 108 65.9 4.2 73.8 76.7 4.8 Rh 168 166 0.5 0.04 159 5.3 0.2 167 0.6 0 166 1,2 0.04 90.5 46.1 1.9 113 32,7 1,1 Re 33 33 0 0 32 5 0.2 28 17.4 0.1 29.8 12 0.1 12.1 64.3 0.4 12.9 61.9 0.4 Cu 10700 9640 four twenty 9430 11.8 16 10060 6 13 10570 1,2 2.6 9415 12 16 9900 7.4 16 Ni 79 76 2 0.06 72 8.7 0.14 73 7.4 0.15 73 7.5 0.15 73 7.5 0.15 80 0 0

Example 6. To assess the effects of pretreatment conditions of lignin on its sorption properties, a series of experiments was conducted with different pH of the processing solution. In all experiments, lignin was treated with a solution of potassium butyl xanthate with a concentration of 10 g / dm ³ for 5 hours, and then gold was sorbed with treated lignin from an underground leaching solution containing 0.2 mg / dm ³ gold and 1 g / dm ³ HCl. The results of the experiments are presented in table 6.

Table 6 Indicators pH of the treatment solution 2 2,5 5 7 9 10 eleven 11.5 12 The residual gold content, mg / DM ³ 0.17 0.09 0,035 0,027 0.011 0.009 0.009 0.019 0,03 SOYE, mg / g 1.3 3,7 5.8 5,4 7.5 7.6 7.2 5.1 3.9

A comparative analysis of known technical solutions, including the method selected as a prototype, and the alleged invention allow us to conclude that it is the totality of the claimed features that ensures the achievement of the perceived technical result. The implementation of the proposed technical solution makes it possible to selectively extract precious metals from various technological solutions containing micro amounts of silver, gold, platinum and (or) palladium on a high concentration salt-acid background without prior preparation for their acidity and salt composition. The effective sorption selectivity of sorbents: lignin, activated carbon, etc., pretreated with aqueous solutions of dithiofluoric acid O-esters and their derivatives, ensures the achievement of a high degree of extraction of target components from complex technological solutions, and selectively select noble metals in one operation.

Claims (3)

1. The method of extraction of precious metals from solutions by sorption, including pre-treatment of the sorbent with a reagent and contacting the solution with the treated sorbent, characterized in that the preliminary treatment of the sorbent is carried out using an aqueous solution of dithiofaric acid derivatives of O-esters as a reagent. 2. The method according to claim 1, characterized in that the salts of O-ethyl or O-butyl esters of dithiofaric acid or sodium cellulose xanthate are used as derivatives of dithiofaric acid O-esters. 3. The method according to claim 1, characterized in that when extracting precious metals from solutions containing non-ferrous metals, lignin is used as the sorbent, and its treatment with an aqueous solution of dithiofaric acid derivatives of O-esters is carried out at pH 9-11.