RU2026389C1 - Method of gold extraction from cyanide liquids and pulps - Google Patents

Abstract

FIELD: metallurgy. SUBSTANCE: process is carried out at the selective effect of direct and alternating current fields on the processes of acid and thiourea treatment of sorbent. EFFECT: improved method of gold extraction. 1 dwg, 3 tbl

Description

 The invention relates to the metallurgy of noble metals and can be used to extract gold from cyanide solutions by sorption.

 The prospective development of the production of precious metals is primarily associated with the involvement in the processing of ores that are poor in the target metal with complex multicomponent composition.

 Sorption leaching of such ores is characterized by saturation of the sorbent in addition to the target component with a number of other impurity ions leached from the ore (copper, iron, zinc, nickel, etc.). Moreover, they account for 75-85% of the sorbent capacity. It is clear that effective process control is impossible without the development of selective methods for extracting gold from a solution.

 A known method of extracting gold and silver from cyanide solutions and pulps by sorption on activated carbon, followed by desorption of the metal.

 The disadvantages of this method are the low availability (activated carbon is obtained by crushing and pyrolysis of apricot kernel) and low mechanical strength of activated carbon. According to one of the gold mining enterprises, coal losses during sorption leaching are an order of magnitude higher than losses of macroporous polymer sorbents, for example, AM-2B grade.

 A known method of electrochemical regeneration of ion-exchange material by displacing sorbed ions in an electric field of direct current.

 The disadvantage of this method is that it can only be used in the processing of sorbents (and naturally solutions), saturated only with the target component. In real conditions of hydrometallurgical production, the use of a known method would lead to sorption and the release of the entire mass of dissolved impurities from the sorbent, which is unacceptable when using this technology.

 There is also a method of extracting gold from cyanide solutions or pulps by sorption on a polymer sorbent (anion exchange resin AM-2B) followed by desorption, which includes sequential treatment of the sorbent with solutions of sodium cyanide, sulfuric acid and thiourea and selected as a prototype.

 The disadvantages of the prototype are the high cost of time and chemicals for the extraction of gold from the sorbent.

 The purpose of the invention is to increase the productivity of gold extraction by increasing the intensity of extraction of the components of the sorbent and reducing the consumption of chemicals.

 The goal is achieved by the following: excludes the processing of saturated sorbent with sodium cyanide; processing with a solution of sulfuric acid is performed by applying a direct current; treatment with a solution of thiourea is performed by applying alternating current.

 According to the existing technology, for the extraction of iron and copper, the saturated sorbent is treated with a solution of sodium cyanide, and when the components of zinc and nickel are extracted, a solution of sulfuric acid.

 The application of a direct electric current to the process of sulfuric acid treatment of the sorbent provides the possibility of collective desorption of polymetals, thereby eliminating the need for treatment with sodium cyanide.

 The application of an electric current to the process of processing the sorbent with a thiourea solution activates the formation of a cationic complex of gold, as a result, the processing time and reagent consumption are reduced.

 The drawing shows a device that implements the proposed method.

 The process of gold extraction is implemented in a column, which is a working tank 1 - a stainless steel cylinder with a diameter of 40 mm and a height of 200 mm, equipped with a bottom 2 and top 3 drainage covers, providing unhindered filtration of the eluent. The solutions were fed into the column from the bottom up from the Marriott vessel 4, providing a constant in time gradient of pressure, to the fitting of the drainage cover 2 and after elution were collected through the connection of the cover 3 into a measuring vessel 5. A central electrode 6 made of a titanium rod with a diameter of 5 mm was installed coaxially with the working vessel 1 3 mm. In the course of the experiments, the electrodes (the body of the working capacitance served directly as the second electrode) were fed with direct or alternating electric current from sources 7 and 8.

 The column was loaded with saturated macroporous sorbent 9 of the AM-2B grade (100 ml of ion-exchange resin in an air-dry state) and the operations of acid treatment (sulfuric acid concentration 40 g / l) and thiourea sorption - gold desorption (acidic thiourea solution, thiourea concentration 90 g) were reproduced / l, sulfuric acid concentration of 20 g / l) according to the existing and claimed methods.

 In all cases, the operation time was identified at a given element flow rate upon reaching the Ж / Т parameter (ratio of the volumes of liquid and solid phases participating in the experiment), a certain value (Ж / Т = 6 during acid treatment, Ж / Т = 10 during thiourea treatment ) At intervals W / T = 1, eluate samples were taken for chemical analysis.

 A stabilized power source (B5-49) was used as current sources for generating direct voltage and a laboratory autotransformer (LATR-1M) for generating industrial-frequency voltage.

 For reasons of maintaining the stability of the thermodynamic conditions of the experiment, the electric field strength was set equal to 0.5 V / cm.

 Information on the kinetics of gold is presented in table. 1. The degree of gold extraction during the process according to the claimed method is 98.1% relative to the initial content on the resin, when carrying out the process according to the prototype - 70.9%. When carrying out two operations (treatments) with the application of only direct current, the degree of gold recovery was 50.6%.

 The kinetics of desorption of iron and copper is shown in table. 2 and 3. The degree of extraction of iron during the process according to the claimed method is a total of 89.3%, while in the stage of acid treatment extracted 74.6%. The degree of iron extraction during the process of the prototype is 7.1%.

 The degree of copper extraction during the process of the present method is 91%, while together with gold (at the stages of the parameter W / T = 9-16), 22.5% is desorbed. The same indicators during the prototype process are 86% and 73%, respectively. When carrying out the process with the application of only alternating current, 87% of the copper is extracted together with gold.

 Thus, the process of gold extraction by the proposed method provides a complete (98.1%) recovery of gold from the sorbent, while the time spent on the thiourea treatment stage is reduced by 25%, respectively, the consumption of thiourea and sulfuric acid is reduced; provides the possibility of selective desorption of iron and copper impurities at the stage of acid treatment; this eliminates the need for time and reagent for cyanide treatment of the sorbent, which in addition to the technical and economic focus solves the problem of improving the environmental situation of production.

Claims (1)

 METHOD FOR GOLD EXTRACTION FROM CYANIDE SOLUTIONS AND PULP, including gold sorption on macroporous anion exchangers followed by desorption of impurities by sulfuric acid solution and gold desorption by thiourea sulfate solution, characterized in that, in order to increase gold recovery productivity by increasing the rate of extraction of gold and reducing components from sorbent chemical consumption, sulfate treatment is carried out by applying a direct electric current, and treatment with a sulfate solution of thiourea us - upon application of an alternating electric current.

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