RU2418082C1 - Procedure for processing sulphide gold-copper concentrates with extraction of gold - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: procedure for processing sulphide gold-copper concentrates with extraction of gold consists in cyanide leaching with additives of ammonia compounds at molar ratio NH₃:CN=1-3. Also, cyanide leaching is performed at concentrations of sodium cyanide 0.05-0.15 g/l in leaching solution under conditions of automatic stabilisation of pH of solution and concentration of sodium cyanide. Leaching is carried out, replenishing solution with cyanide and ammonia. Cyanide and ammonia are replenished automatically with ammonia-cyanide solution.

EFFECT: optimisation of conditions of cyanide leaching.

2 cl, 2 tbl, 2 ex

Description

The invention relates to the field of metallurgy of noble metals (BM), in particular to the hydrometallurgical processing of concentrates containing noble, non-ferrous metals and sulfides.

The target product of the processing of ores containing precious metals are concentrates represented by iron and non-ferrous metal sulfides (pyrite, pyrrhotite, tennantite, chalcopyrite, etc.).

A known method of processing sulfide gold-copper concentrates, which consists in pyrohydrometallurgical processing in place using the process of oxidation-sulfatization roasting, which allows the conversion of copper sulfides into water and acid-soluble compounds. After oxidation-sulfatizing roasting, copper is leached from the cinder (the solvent is H ₂ SO ₄ ), after copper extraction, cinder is alkalized, followed by cyanidation [1].

The disadvantages are high capital and operating costs, due to the duration of the technological cycle, cleaning and neutralization of a large volume of firing gases.

There is also known a method of cyanide leaching of gold-copper sulfide concentrates in the presence of ammonia, which is adopted as a prototype, as the closest to the claimed technical solution. These studies were carried out under the following conditions: duration of cyanide leaching 24 hours; the concentration of sodium cyanide in a solution of 2.5-11.5 g / l; the pH of the medium ranged from 9.4-11.7; ammonia was added to the leaching medium in the form of ammonium chloride (NH ₄ Cl) at a molar ratio of NH ₃ : CN from 1: 1 to 10: 1, where the most optimal parameters, according to the criterion for the consumption of sodium cyanide, and the extraction of gold into the solution were obtained at a molar the ratio of NH ₃ : CN - 1: 1; 2: 1; 3: 1 and sodium cyanide concentrations of 2.5 kg / t. In this case, the solution, during the entire leaching time, was periodically supported by sodium cyanide and ammonia [2].

The disadvantage of this method is the high consumption of sodium cyanide with a low recovery of gold in solution.

The problem to which the invention is directed, is to provide acceptable indicators for the extraction of gold from gold-copper sulfide concentrates at low costs of sodium cyanide.

The problem is solved due to the technical result, which consists in optimizing the conditions of cyanide leaching.

The technical result is achieved by the fact that in the method of processing sulfide gold-copper concentrates with gold recovery, including cyanide leaching with additives of ammonia compounds at molar ratios of NH ₃ : CN - 1-3, according to the invention, cyanide leaching is carried out at concentrations of sodium cyanide 0.05-0, 15 g / l in a leach solution under conditions of automatic stabilization of the pH of the solution and the concentration of sodium cyanide when the solution is reinforced with cyanide and ammonia. Reinforcement for cyanide and ammonia is carried out automatically by an ammonia-cyanide solution.

The essence of the method is as follows.

Cyanide leaching occurs at a stable, low concentration of sodium cyanide and a constant pH of the medium, where the blocks of automatic determination (C _NaCN , pH) and reinforcement with reagents provide a constant concentration of free cyanide and a pH of the medium. Ammonia is fed into the leaching medium together with a concentrated solution of sodium cyanide in the form of ammonium hydroxide (NH ₄ OH) in a given molar ratio of NH ₃ : CN.

The concentration of sodium cyanide 0.05-0.15 g / l was selected based on studies. When the concentration of sodium cyanide is less than 0.05 g / l and more than 0.15 g / l, there is an increase in the consumption of sodium cyanide and a decrease in the extraction of gold in the solution.

A comparative analysis of the proposed technical solution with the prototype show the presence in it of a significant feature that distinguishes it from the prototype, which allows us to conclude that the claimed technical solution meets the criterion of "novelty."

No technical solutions have been identified from the prior art that have features that match the distinguishing features of the present invention, therefore, it can be considered that the proposed technical solution meets the criterion of "inventive step".

The method is illustrated by the following examples.

For experimental verification of the prototype and the proposed method used flotation concentrate obtained by the beneficiation of sulfide gold-copper ores. The size of the flotation concentrate is not less than 95% of the class minus 0.074 mm. The chemical composition of the concentrate is shown in table 1.

Table 1 Chemical composition of flotation concentrate Content, mass fraction,% Cu Fe S As Sb Pb Zn Au g / t Ag, g / t 8.7 29.4 37.6 1,57 0.17 0.12 0.33 36,2 67.8

Example 1. The proposed method.

The cyanide leaching of a sulfide gold-copper concentrate was carried out using an automatic determination and maintenance of a stable concentration of free sodium cyanide in solution and pH of the medium; the installation diagram is shown in the drawing. It consists of: 1 - pH meter-millivoltmeter; 2 - block automatic titration (BAT-15.1); 3 - the electromagnetic valve; 4 - mixer; 5 - a glass cup; 6 - calibrated consumables for alkaline, cyanide and ammonia-cyanide solutions; 7 - stirrer drive; 8 - auxiliary capacity; 9 - electrolytic key; 10 - silver chloride reference electrode; 11 - ion-selective electrode; 12 - temperature electrode; 13 - pH measuring electrode; 14 - a heating device.

The experimental procedure was as follows: the initial concentrate was loaded into a glass beaker and water was added in a certain proportion, mixed to a homogeneous mass. After that, a unit for automatic determination and maintenance of the pH of the medium, which automatically stabilized the pH of the medium at specified values, was turned on. After stabilization of the pH of the medium, the unit included an automatic determination and maintenance of the concentration of sodium cyanide in the leaching medium. The cyanide and ammonia reinforcement was carried out automatically by an ammonia-cyanide solution.

At the end of the experiment, the pulp was sent for filtration, the resulting solutions were analyzed on an Au, Ag, Cu atomic absorption method, cake after washing was analyzed on an Au, Ag, Cu assay with a chemical end.

The parameters of the experiment:

- the duration of cyanide 24 hours;

- grinding size 95% of the class minus 0.074 mm;

- the concentration of sodium cyanide 0.05-0.15 g / l;

- ratio W: T = 2: 1;

- pH of the medium 10.7.

Example 2. The method of the prototype.

The cyanide leaching of sulfide gold-copper concentrate was carried out according to previously published research results used in cyanidation of sulfide gold-copper concentrates [2].

The experimental procedure was as follows: cyanide leaching was carried out in a bottle agitator. The initial concentrate was loaded into the bottle and water was added in a certain proportion, it was all mixed until a homogeneous mass, after which the leaching medium was alkalized to a certain pH, then sodium cyanide (NaCN) and ammonium hydroxide (NH ₄ OH) were separately fed to a predetermined concentration. Reinforcement for sodium cyanide and ammonia was carried out by fractional supply of cyanide and ammonia according to the results of titration of NaCN with silver nitrate in the presence of KJ.

At the end of the experiment, the pulp was sent for filtration, the resulting solutions were analyzed on an Au, Ag, Cu atomic absorption method, cake after washing was analyzed on an Au, Ag, Cu assay with a chemical end.

The parameters of the experiment:

- the duration of cyanide 24 hours;

- grinding size 95% of the class minus 0.074 mm;

- the concentration of sodium cyanide 2.5 g / l;

- ratio W: T = 2: 1;

- pH of the medium is not lower than 10.5.

The results of the experiments are presented in table 2.

table 2 The results of the experiments Example The ratio of NH ₃ : CN C _NaCN , g / l The extraction of Au in the solution,% NaCN consumption, g / l one 0: 1 0.05 79.6 6.73 1: 1 82.1 4.94 2: 1 84.6 3.71 3: 1 85.6 3.15 0: 1 0.1 84.3 7.64 1: 1 86.7 5.34 2: 1 90,4 4.12 3: 1 91.1 3.92 0: 1 0.15 83.3 11.87 1: 1 87.8 9.43 2: 1 91.5 8.28 3: 1 91.9 5.7 2 0: 1 2.5 67.6 41.6 1: 1 57.1 39.2 2: 1 75.7 20.3 3: 1 73.6 18.7

From the obtained results of the experiments it follows that when leaching according to the proposed method, within the range of sodium cyanide concentrations of 0.05-0.15 g / l, the extraction of gold in solution at different molar ratios of NH ₃ : CN is 79.6-91.9% at sodium cyanide consumption 11.87-3.15 kg / t.

The extraction of gold into the solution according to the prototype method is 57.1-75.7% with a consumption of sodium cyanide 41.6-18.7 kg / t.

The proposed method can be used in the processing of gold-copper concentrates.

Information sources

1. Lodeishchikov VV Technology for the extraction of gold and silver from refractory ores. - Irkutsk: OJSC Irgiredmet, 1999, Vol. 2.

2. Muir D.M., La Brooy S.R. and Cao. Recovery of Gold from copper-bearing ores // Gold Forum on Technology and Practices: World Gold'89. - Littlton, Colorado, USA. - 1989, p. 363-374.

Claims (2)

1. A method of processing sulfide gold-copper concentrates with the extraction of gold, including cyanide leaching with additives of ammonia compounds at a molar ratio of NH ₃ : CN = 1-3, characterized in that the cyanide leaching is carried out at concentrations of sodium cyanide 0.05-0.15 g / l in a leach solution under conditions of automatic stabilization of the pH of the solution and the concentration of sodium cyanide when the solution is reinforced with cyanide and ammonia. 2. The method of claim 1, characterized in that the cyanide and ammonia reinforcement is carried out automatically by an ammonia-cyanide solution.

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