RU2310692C1 - Gold saturated anion-exchange resins regeneration process - Google Patents

Abstract

FIELD: hydraulic metallurgy of noble metals, possibly processes of sorption type extraction of gold from productive solutions of underground, heap and agitation leaching of ores.

SUBSTANCE: process comprises steps of treating gold-saturated anion-exchange resin by means of mineral acid solution; desorbing and washing out resin. Desorption is realized by means of sodium sulphite solutions with pH 4.5 - 6.5 and concentration 50 - 200 g/l. Washing out of resin is realized by means of solutions of sodium chloride with concentration 100 - 200 g/l. Washing out solution of sodium chloride containing sodium sulphite is used in return cycle as desorbent after final stabilizing of it by means of sodium sulphite.

EFFECT: simplified accelerated process of anion-exchange resins regeneration due to lowered number of stages, possibility for using method for processing solutions of ore hydraulic chlorination.

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Description

The invention relates to hydrometallurgy of precious metals and can be used in the technology of sorption extraction of gold from productive solutions of underground, heap and agitation leaching of ores.

A known method of regeneration of resins saturated with noble metals, including treatment with a solution of mineral acid, sorption of thiourea, desorption of noble metals with acid solutions of thiourea, washing the resin from thiourea with a solution of mineral acid, washing the anion exchange resin with water, alkaline treatment to convert the resin into a hydroxyl form and final washing the resin with water (A.S. SU No. 890738, BI No. 9, publ. 07.03.88).

The disadvantages of this method are the duration and multi-stage process.

Closest to the proposed method is the regeneration of ion-exchange resins saturated with noble metals, which includes acid treatment, sorption of thiourea, desorption of noble metals with acid solutions of thiourea, washing the resin from thiourea with water, alkaline treatment to convert the resin into a working (hydroxyl) form and final washing of the resin water (Patent RU No. 2040561, BI No. 21, publ. 07.27.95).

The disadvantages of this method are the duration and multi-stage process.

The technical result of the invention is to simplify the process of regeneration of ion-exchange resins by reducing the number of stages, accelerating the regeneration process, and also the ability to use the method for processing solutions of hydrochlorination of ores.

The technical problem is solved in that in the known method of regeneration of anion-exchange resins saturated with gold, including treatment with a solution of mineral acid, desorption of gold and washing of the resin, the desorption of gold from the resin is carried out with acidified to a pH of 4.5-6.5 sodium sulfite concentration of 50-200 g / l, and resin washing is carried out with solutions of sodium chloride with a concentration of 100-200 g / l, the solution after washing, containing sodium chloride and sodium sulfite, is used in the circulation as a desorbent after being fortified with sodium sulfite.

The essence of the method lies in the fact that for the desorption of precious metals used cheap and non-deficient reagents - sulfite and sodium chloride. In contrast to thiourea, the hydrosulfite ion is much weaker sorbed by anion exchangers, especially in the presence of a chloride ion, and the residual sulfite content in the resin is easily washed out with sodium chloride solutions. In addition, the anion exchange resin is immediately charged into the working (chloride) form and, without additional processing, can be used in the sorption cycle. The desorption solution contains 50-200 g / l sodium sulfite and has a pH of 4.5-6.5. Sodium sulfite is a complexing agent and allows you to convert gold into an anionic sulfite form, weakly adsorbed by resins. When the concentration of sodium sulfite in the solution is less than 50 g / l, it is not enough to shift the equilibrium of complexation towards the sulfite form of gold, which leads to a decrease in the degree of desorption of gold. The concentration of sodium sulfite in a solution of more than 200 g / l is impractical due to the fact that it does not lead to a significant increase in the degree of gold recovery, leads to unnecessary economic costs. Since sodium sulfite is a typical reducing agent, with a decrease in the pH of the stripping solution below 4.5 in the ionite phase, a redox process occurs with the participation of gold (III) present in the anion exchange resin in the form of an AuCl ₄ ^- ion. In this case, gold is restored to its elemental state, turning into a non-desorbable form. Accordingly, there is a decrease in the degree of extraction of gold. With an increase in the pH of the stripping solution above 6.5, a partial alkaline hydrolysis of gold occurs, which is accompanied by its translation into an insoluble form in the sorbent phase. As a result, the degree of extraction of gold from the resin is also reduced. In addition, hydrosulfite ions (HSO ₃ ^- ) at pH above 6.5 are converted to sulfite ions (SO ₃ ^2- ), which are more strongly retained by anion exchange resin and complicate the subsequent stage of resin regeneration.

To transfer the resin into the working form (chloride), the resin is washed with a solution of sodium chloride after desorption, which contributes to the course of the ion-exchange reaction

The concentration of sodium chloride in solutions at the stage of regeneration is 100-200 g / l. When the content of sodium chloride in the solution is less than 100 g / l, a sufficient concentration of Cl ^- - ions in the solution is not provided to shift the equilibrium of this reaction in the direction of the transition of sulfite ions into solution. The concentration of sodium chloride in a solution above 200 g / l is impractical due to the fact that it leads to unjustified economic costs and technological difficulties associated with the solubility of sodium chloride. Gold desorption by pure solutions of sodium chloride practically does not occur. After washing the anion exchange resin with solutions of sodium chloride, the solutions flowing out of the column with anion exchange resin after being fortified with sodium sulfite can be used in circulation as a stripping solution,

An example of a prototype. The ion-exchange resin saturated with gold from a productive hydrochlorination solution is placed in a column and treated with a 3% sulfuric acid solution at 40 ° C for 24 hours with an eluent flow rate of 3-4 vol / vol. pitches.

Then, to prepare the resin for desorption of noble metals, sorption of thiourea is carried out by feeding a solution containing 6% thiourea and 2.5% sulfuric acid to the column for 48 hours at an eluent flow rate of 2-3 vol / vol. pitches.

Then gold is desorbed, feeding for 96 hours an acidic solution of thiourea containing 9% thiourea and 3% sulfuric acid with an eluent flow rate of 3-4 vol / vol. pitches.

After desorption, the anion exchange resin is washed from thiourea and acid with water at a flow rate of 5-6 vol / vol for 24 hours. pitches.

Next, the anion exchange resin is treated in the column for 24 hours with a 4% sodium hydroxide solution with an eluent flow rate of 2-3 vol / vol. pitches.

To assess the amount of washed salts at the stage of acid treatment of the resin, all the filtrates after acid treatment were combined, evaporated and weighed dry residues. The residual gold content on the regenerated resin and the degree of gold desorption were determined by analysis of all solutions — filtrates formed in the regeneration process. The relevant data are given in the table.

The proposed method is as follows.

An example of the proposed method. In accordance with the proposed method, a sequential scheme of ion-exchange resin regeneration was checked: acid treatment, desorption with sodium sulfite, washing with sodium chloride.

The ion-exchange resin saturated with gold from a productive hydrochlorination solution was placed in a column and treated with a 3% solution of sulfuric acid at 40 ° С for 24 h with an eluent flow rate of 3-4 vol / vol. resin or 5% hydrochloric acid at 20-25 ° C with an eluent flow rate of 3-4 vol./about. resin for 24 hours

Then, to prepare the resin for desorption, the anionite was washed from the acid with water with an eluent flow rate of 2-3 vol / vol. resin for 12 hours. The resulting solution was used after the addition of mineral acid in the next cycle to process a new portion of the resin.

Then gold was desorbed by feeding a solution of sodium sulfite acidified to pH 4.5-6.5 with a concentration of 50-200 g / l with an eluent flow rate of 5-6 vol / vol. anion exchange resin for 24 hours

After desorption, the anion exchange resin was treated in a column for 24 h with a solution of sodium chloride at a concentration of 100-200 g / l with an eluent flow rate of 2-3 vol / vol. pitches. The solution after washing, containing sodium chloride and sodium sulfite, was used after adding sodium sulfite in the next cycle to carry out the desorption of gold from a new portion of the resin.

To assess the amount of washed salts at the stage of acid treatment of the resin, all the filtrates after acid treatment were combined, evaporated and weighed dry residues. The residual gold content on the regenerated resin and the degree of gold desorption were determined by analysis of all solutions — filtrates formed in the regeneration process. The corresponding data for the boundary and average values are given in the table.

Table Way The gold content in saturated anion exchange resin, mg / g The number of stages of the regeneration process Stage of the regeneration process Reagent used at the stage of the regeneration process Reagent consumption, vol./about. Time to the stage of the regeneration process, h The amount of washed salts in g with 1 g of dry anion exchange resin The degree of extraction of gold in p-p at the stage of washing to transfer to working form The residual gold content in the resin, after the stage of the process, mg / g Famous 9.5 5 Washing
mineral acid 3% sulfuric
acid four 24 0.210 0.05 9.49 Desorption Preparation p-p 6% thiourea and 2.5% sulfuric acid 3 48 - 2,4 9.27 desorption p-p 9% thiourea and 3% sulfuric acid four 96 - 48,2 4.81 Thiourea resin washing water 6 24 - 0.86 4.80 rinsing resin for conversion to working form 4% solution of caustic soda 3 24 - 3.12 4,311 mineral acid washing 3% sulfuric acid four 24 0,200 0.05 9.49 water wash water 3 12 0.009 0.006 9.49 The proposed method 9.5 3 desorption pp Na ₂ SO ₃ 50 g / l with the addition of 100 g / l NaCl, pH 4.5 6 24 91.6 0.793 rinsing resin for conversion to working form p-p 100 g / l NaCl 3 24 - 0.06 0.788 mineral acid washing 5% hydrochloric acid four 24 0.150 0,047 9,496 water wash water 3 12 0.006 0.005 9,496 The proposed method 9.5 3 desorption pp Na ₂ SO ₃ 50 g / l with the addition of 100 g / l NaCl, pH 4.5
pp 100 g / l NaCl 6
3 24
24 -
- 92.0
0,044 0.756
0.751 flushing resin to convert to mineral acid washing 5% hydrochloric acid four 24 0.150 0,047 9,496 The proposed method water wash water 3 12 0.006 0.005 9,496 9.5 3 desorption pp Na ₂ SO ₃ 200 g / l, pH 5.5 6 24 - 92.9 0.67 rinsing resin for conversion to working form p-p 200 g / l NaCl 3 24 0,052 0.665 mineral acid washing 5% hydrochloric acid four 24 0.150 0,047 9,496 The proposed method water wash water 3 12 0.006 0.005 9,496 9.5 3 desorption pp Na ₂ SO ₃ 100 g / l with the addition of 50 g / l NaCl, pH 6.5 6 24 - 95.4 0.432 rinsing resin for conversion to working form p-p 150 g / l NaCl 3 24 0,049 0.427

The results show that washing a saturated ion-exchange resin with acid solutions (3% sulfuric or 5% hydrochloric) practically does not depend on the nature of the acid and can significantly reduce its total salt content, practically without affecting (without desorbing) gold.

Gold-containing sulfite solutions are sent to the separation of gold by precipitation after acidification with mineral acid.

Carrying out resin regeneration according to the proposed method can significantly reduce the process time (from 216 hours to 84 hours), that is, speed up the process, as well as reduce the number of process steps (from 5 to 4).

Conducting experiments on the use of regenerated resin for re-saturation with gold from a productive solution of underground leaching with hydrochlorination showed that the capacity of the resin for gold remains high, which confirms the quality of regeneration.

Thus, the proposed method for the regeneration of ion exchange resins in comparison with the prototype allows using the mixed solution of sulfite and sodium chloride, acidified to pH 5-6, to achieve the following positive results:

- speed up the process;

- simplify the process by reducing the number of operations;

- use the method for the regeneration of ion exchange resins saturated with chloride productive solutions of underground, heap, agitation leaching by hydrochlorination;

- reduce the cost of the process through the use of cheap reagents and their partial use in circulation.

Claims (2)

1. The method of regeneration of anion exchange resins saturated with gold, comprising treating the resin with a solution of mineral acid, desorption of gold and washing the resin, characterized in that the desorption of gold is carried out acidified to a pH of 4.5-6.5 sodium sulfite concentration of 50-200 g / l and washing is carried out with a solution of sodium chloride concentration of 100-200 g / L. 2. The method according to claim 1, characterized in that the solution after washing, containing sodium chloride and sodium sulfite, is used in circulation as a desorbent after being fortified with sodium sulfite.