The method of extraction of precious metals

 

(57) Abstract:

The invention relates to hydrometallurgy of precious metals, in particular to the recovery of precious metals from cyanide solutions and/or slurries. The method of extraction of precious metals includes sorption, desorption, cooling solutions and electrolysis. What's new is that after desorption solution is divided into rich and poor, the poor part is sent again to the desorption and the rich part without refrigeration sent to electrolysis. The method allows to increase the concentration of noble metals in the solutions sent to electrolysis.

The invention relates to the field of hydrometallurgy of precious metals, in particular to the recovery of precious metals from cyanide solutions and/or slurries.

In the process of extracting precious metals from ores widespread find technology-based processing of ores or concentrates cyanide solutions. From cyanide solutions of noble metals extracted using various technologies, for example, adsorption on charcoal, desorption and deposition on zinc or adsorption on charcoal, desorption and electrolysis. Of great importance is the problem of increasing the efficiency sigh processing technologies to be used.

The method for extracting noble metals, closest to the proposed technical solution adopted for the prototype, on which the noble metal is subjected to sorption on coal, the coal is subjected to elution in an autoclave with a solution of 1-2% sodium hydroxide and 1% sodium cyanide at a temperature of 383 K (110oC). After 48 h of coal eluted 96-97% gold. The eluate was cooled to 353 K (80o(C) sent to electrolysis [1].

The disadvantages of the method include:

- wasteful expenditure of energy due to cooling of the solution before electrolysis;

- low concentration of noble metals in the eluates sent to electrolysis;

a significant duration of the whole process.

Object of the invention is the reduction of energy consumption and the duration of the whole process.

The problem is solved at the expense of achieving a technical result, which is to increase the concentration of noble metals in the eluates sent to electrolysis.

This technical result is achieved by the fact that in the known method of extracting precious metals from solutions, including their sorption on coal, desorption with getting hot Rast the percent content of noble metals parts, the poor part is sent again to the desorption for their enrichment and rich part without refrigeration sent to electrolysis.

The essence of the proposed method is based on the following:

when the secondary use of the poor of the eluates at the stage of desorption is enriched these eluates noble metals, which leads to increased concentration of noble metals in the solutions sent to electrolysis;

as the electrolysis according to the proposed method is conducted without prior cooling of the eluates, the hot solution during electrolysis leads to an increase in the conductivity of the electrolyte, the reduction of electrode polarization, reducing tension on the tub and possible passivation of the anodes, which ultimately leads to reduction of specific energy consumption.

Comparative analysis of the proposed method with the prototype shows that the proposed method of recovery of precious metals from the prototype differs. Thus, the proposed solution meets the criterion of "novelty".

To prove compliance of the claimed invention, the criterion of "inventive step" was compared with druging metal meets the criterion of "inventive step", as the totality of its distinctive characteristics, namely the separation of the eluate on the rich and the poor, with the return of the latter on desorption, the direction of the first directly to the electrolysis, and cooling the solution after electrolysis provides the possibility of increasing the concentration of noble metals in the eluates spent on electrolysis, and improve the efficiency of electrolysis, which is not obvious from the prior art.

An example of using the proposed method

For experimental verification of the proposed method used the resulting sorption coal of mark AG 95 containing 5 g/kg of gold weighing 200 g of This coal was filed on desorption carried out at a temperature of 430 K (160oC) a solution containing 4 g/l of sodium hydroxide. The feed rate of the solution was 4 l/h of the First 3.0 volume (1.2 l) eluates out of desorber, had a gold concentration of 580 mg/L. These solutions were sent to the electrolysis is carried out under pressure. The next three volumes of the eluates (1.2 l) had a gold concentration of 125 mg/L. These poor eluate sent back to desorption as the Stripping solution. While the eluate enriched in gold, the mass concentration of the electrolysis. The cooling solutions was performed after electrolysis to a temperature of 323 K (50oC). As this solution contained about 10 mg/l of gold, he was sent on the sorption for full obezbalivaniya. Treatment duration was 1 hour. Residual gold content in coal - 0.1 g/kg Thus, the gold recovery was 98%.

An example of the method on the prototype

For experimental verification of the method on the prototype used the resulting sorption coal of mark AG 95 containing 5 g/kg of gold weighing 200 g of the coal under the terms of the way the prototype was submitted to the desorption carried out at a temperature of 383 K (110oC) a solution containing 2% (20 g/l) of sodium hydroxide and 1% (10 g/l) of sodium cyanide. The feed rate of the solution was 1 l/h After desorption solution was cooled to a temperature of 353 K (80oC) and sent to the electrolysis. The maximum concentration of Au was 100 mg/l 48 h achieved a gold recovery of 96% - residual gold content in coal amounted to 0.2 g/kg

Thus, the proposed method of extraction of metals provides the possibility of increasing the concentration of noble metals in the eluates sent to the electrolysis Prim solutions without pre-cooling. The duration of the process of the proposed method was 1 h, and the way the prototype 48 h, therefore, the duration of the whole process decreased 48 times, resulting in energy costs have been reduced accordingly.

For the proof of the criterion of "industrial application" suffice it to say that the issue about its use on construction enterprises production Association "Yuzhuralzoloto".

Sources of information

1. Meretukov M. A., Orlov A. M. metallurgy of noble metals (foreign experience). - M.: metallurgy, 1990, S. 174-175.

The method of extracting precious metals from solutions, including their sorption on coal, desorption with getting hot solutions of eluates and electrolysis, characterized in that solutions of the eluates after desorption is divided into rich and poor in content of noble metals parts, poor part is sent again to the desorption for their enrichment and rich part without refrigeration sent to electrolysis.

 

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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.

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