CN85100106B - Full Wet Refining Process of Gold Cyanide Slime - Google Patents

Abstract

The invention discloses a full-wet refining process of gold cyanide mud, and belongs to the field of precious metal extraction. At present, most of the cyanide gold mud adopts a water method enrichment-fire method smelting-electrolytic refining method to prepare pure gold, the process is complex, and the loss of gold and silver is large. The invention provides a full-wet process which takes an extraction method as a main body and directly prepares pure gold from gold mud, and can recover valuable metals such as silver and the like. The recovery rate of gold can reach more than 99%. The main procedures in the process include dissolving aqua regia, extracting gold, leaching the insoluble residue of aqua regia with ammonia water, and reducing hydrazine hydrate to obtain silver. The process is suitable for various grades of gold cyanide mud, acid-washing gold mud, gold-silver alloy and gold-containing materials accompanied by elements such as zinc, copper, silver, iron, lead and the like.

Description

Full Wet Refining Process of Gold Cyanide Slime

The invention relates to a precious metal extraction process, in particular to a technology for extracting gold and silver from gold cyanide mud by hydrometallurgy.

Cyanide gold mud is a primary gold product obtained from gold ore after mineral processing, cyanide solution leaching, and zinc powder (silk) replacement. The gold and silver are of low grade and contain excessive zinc and other impurities. In order to increase the gold content, the gold mud is generally pickled to remove impurities, and the pickled gold mud is obtained, which is then smelted into gold-silver alloy and sold as the final product of the gold mine. If pure gold is to be obtained, the methods of water enrichment-fire smelting-electrolytic refining are mostly used. This traditional method is not only complex in process, diverse in equipment, poor in operating conditions, and long in production cycle, but more importantly, the loss rate of gold and silver is relatively high. In the process of enrichment by water method, multiple material transfer operations will easily cause the loss of fine gold mud particles; a considerable amount of low-grade gold-containing blanks such as slag, waste furnace lining, and waste crucible will be produced during pyromelting; the yield of electrolytic refining Low, large material backlog, and small flexibility in processing scale.

The present invention aims to directly prepare pure gold from gold mud by using a full wet process, so as to simplify the refining process of cyanide gold mud, increase the yield of gold, shorten the production cycle and reduce the backlog of materials.

The present invention is characterized in that it proposes a process flow for treating gold cyanide mud by an all-wet method mainly based on an extraction method. After dissolving the gold mud with aqua regia, it undergoes extraction-back-extraction-reduction to obtain pure gold. The extractant used is diisooctyl sulfide [two (2-ethylhexyl) sulfide]. The recovery of valuable metals such as silver and copper is also considered in the process. Fig. 1 is the flow chart of this technology, introduces the present invention as follows below in conjunction with flow chart:

Aqua regia dissolution process The dried and roasted desulfurized gold cyanide mud is dissolved with aqua regia. At this time, gold, zinc, copper, iron and other metals are transferred into the solution, and silver and lead form chlorides and remain in the insoluble slag. When aqua regia dissolves, the solid-liquid ratio is 1: (1-2) [W/V]. Concentrated aqua regia or 1:1 dilute aqua regia can be used. The dissolution temperature can be from room temperature to 90°C, and the dissolution time is 1 to 24 hours. The gold leaching rate is above 99.9%. The leachate was filtered, and the insoluble residue was washed with dilute hydrochloric acid. The filtrate and the washing liquid are combined together and properly diluted so that the acidity reaches 0.5-1.5N, which is the material liquid for extracting gold. This process can also be carried out by adding hydrochloric acid and sodium chlorate under heating conditions, and the extraction material liquid is the chloride medium at this time.

The organic phase during extraction in the extraction process is diisooctyl sulfide plus kerosene, wherein kerosene is a diluent, and the content of diisooctyl sulfide in the organic phase is 30-50% (volume percentage). During the extraction, the volume ratio of the aqueous phase material liquid and the organic phase should be such that the gold loading of the organic phase is not greater than 50 g/L, and the contact time between the two phases should not exceed 1 minute. Gold enters the organic phase during extraction, while other impurities in the feed liquid are not extracted, but remain in the aqueous phase extraction raffinate. Since diisooctyl sulfide has higher antioxidant capacity than ordinary dialkyl sulfide, it can directly extract high-concentration gold not only from hydrochloric acid medium but also from dilute aqua regia medium.

Washing process In order to remove the water phase mechanically entrained in the organic phase during extraction, the gold-containing organic phase is washed with 0.2-0.5N hydrochloric acid for 1-2 times, and the volume ratio of the washing acid to the organic phase is 1: (1-5). The washed aqueous phase returns to the extraction section.

The gold-containing organic phase after washing in the back extraction process is subjected to 1-2 stage back-extraction with an equal volume of alkaline sodium sulfite solution, and the two phases are contacted at room temperature for 5-20 minutes. At this point the gold is transferred to the water phase in the form of sulfite complexes. The composition of the stripping solution is 0.5-1.0M NaOH plus 0.5-1M Na ₂ SO ₃ .

Organic Phase Regeneration Process After degolding, the organic phase can be returned to the extraction process for reuse after being washed with dilute hydrochloric acid and water.

In the reduction process, the gold-containing stripping solution is acidified with hydrochloric acid at 50-70°C, so that the sulfite is converted into sulfur dioxide in the acidic medium. At this time, the gold is reduced to metal and precipitates out of the solution as a brown powdery precipitate. After aging for half an hour, it was filtered, and the precipitate was washed with dilute hydrochloric acid and water. Precipitated mother liquor can be discarded. The gold powder can be boiled and washed with hydrochloric acid if necessary. After precipitation and drying, it is a gold powder product, and the product purity is >99.98%.

Ammonia water immersion silver process After washing with dilute hydrochloric acid, the aqua regia insoluble residue was stirred and immersion silver with 1:1 ammonia water at room temperature. At this time, the silver chloride in the slag is converted into silver ammonium ions and enters the leaching solution, while the lead chloride in the slag is not leached and remains in the ammonia leaching residue, and the lead therein can be recovered by appropriate methods.

Silver reduction process The ammonia immersion solution is reduced by adding hydrazine hydrate solution at 50-80°C. At this time, the silver in the solution is reduced to metal, and gray-white silver powder precipitates are formed. Aging for 0.5 to 2 hours. After the solution is clarified, filter, wash the precipitate with water, and dry to obtain a pure silver powder product.

The scrap iron replacement process contains zinc, copper, iron and other metals in the raffinate. The recovery method depends on the economic rationality. In this process, it is recommended to replace copper with scrap iron and recover copper in the form of copper slag.

The waste liquid after copper replacement in the neutralization precipitation process can be treated by the neutralization precipitation method. If zinc slag is to be recovered, the pH value of the solution can be adjusted to precipitate iron and zinc step by step.

This process is applicable to various grades of cyanide gold mud, pickling gold mud, gold-silver alloy and other gold-containing materials accompanied by zinc, silver, copper, iron and lead. Adopting this process can make the recovery rate of gold > 99%, and the purity is equivalent to that of electrolytic gold. At the same time, the original refining process is greatly simplified, the production cycle can be shortened, and the processing scale can be flexibly controlled.

Embodiment Processed 19.8303 grams of gold-containing gold cyanide mud of 14.67% by this flow process. First use 50 ml of aqua regia to leach the gold mud at 90°C for 1 hour, dilute it with water appropriately and filter it, and wash the insoluble residue with dilute hydrochloric acid. The residue after washing contains 1.822 mg of gold, and the leaching rate of gold is 99.94%. The volume of filtrate and washing water is about 100 milliliters, put together and then extract with equal volume of 50% diisooctyl sulfide kerosene, contact for 1 minute, and then use 20 milliliters of organic phase to extract the second time after phase separation. 0.48 mg of gold remained in the raffinate, and the extraction rate was 99.98%. The two gold-containing organic phases were combined, washed with 25 ml of 0.2N hydrochloric acid, contacted for 1 minute, and the aqueous phase was separated. The washed gold-containing organic phase was back-extracted with an equal volume of 1M NaOH plus 1M Na ₂ SO ₃ solution, the two phases were in contact for 20 minutes, and then 25 ml of back-extraction solution was used for the second back-extraction. 140 mg of gold remained in the organic phase after gold removal, and the stripping rate was 99.95%. The two gold-containing back-extraction solutions are combined and heated to about 60°C. Hydrochloric acid is added to make the solution strongly acidic. At this time, brown gold powder is precipitated. After aging for half an hour, filter, and the precipitate is washed with dilute hydrochloric acid and water. 0.152 mg of gold remains in the mother liquor of reduction precipitation, and the reduction rate is 99.99%. After precipitation and drying, it is 2.9007 grams of pure gold powder, with a yield of 99.7% and a purity of >99.98%.

The aqua regia insoluble residue was stirred and leached with 10 ml of 1:1 ammonia water at room temperature for 1 hour, filtered, and the residue was washed with dilute ammonia water. Heat the filtrate to about 50°C, add 10% hydrazine hydrate, age for half an hour to clarify the solution, filter, wash and dry to obtain 0.52 g of off-white silver powder, with a yield of >98% and a purity of >99%.

Claims (9)

1. A full wet refining method for cyanide gold mud, which is dissolved in aqua regia, extracted with dialkyl sulfide, washed with hydrochloric acid, back-extracted with alkaline sodium sulfite solution, and high-purity gold is produced after reduction, which is characterized in that it is mixed with hydrochloric acid and nitric acid (Dilute aqua regia) directly use diisooctyl sulfide [bis(2-ethylhexyl) sulfide] as the extractant, kerosene as the diluent to extract gold from the organic phase, and the aqua regia insoluble residue is leached with ammonia water to extract silver. The leaching solution is reduced with hydrazine hydrate to obtain pure silver. 2. The method according to claim 1, characterized in that gold cyanide mud is dissolved with aqua regia, the solid-liquid ratio during dissolution is 1: (1-2) [W/V], and the dissolution temperature is from room temperature to 90°C. The dissolution time is 1 to 24 hours. 3. The method according to claim 1, characterized in that the acidity of the aqueous medium during extraction is 0.5-1.5N. 4. The method according to claim 1, 2, 3, characterized in that the composition of the organic phase during extraction is: 30-50% (volume percentage) of diisooctyl sulfide, and the rest is diluent kerosene. The volume ratio of the two phases is selected so that the gold loading of the organic phase is not greater than 50 g/L. 5. The method according to claim 1, characterized in that the gold-containing organic phase is washed with 0.2-0.5N hydrochloric acid, and the volume ratio of the washing solution to the organic phase is 1: (1-5). 6. The method according to claim 1, characterized in that the washed gold-containing organic phase is back-extracted with a solution containing 0.5-1.0M sodium hydroxide and 0.5-1.0M sodium sulfite at room temperature, and two phases are separated during back-extraction. The contact time is 5 to 20 minutes. 7. The method according to claim 1, characterized in that the organic phase after degolding can be washed with dilute hydrochloric acid and water for regeneration and reuse. 8. The method according to claim 1, characterized in that the gold-containing stripping solution is acidified with hydrochloric acid to reduce gold, and the reduction temperature is 50°C-70°C. 9. The method according to claim 1, characterized in that the aqua regia insoluble residue of gold cyanide mud is stirred and leached with 1:1 ammonia water at room temperature, and the leach solution is used to reduce silver with hydrazine hydrate, and the reduction temperature is 50-80°C.

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