CN1163314A

CN1163314A - Technical process for extracting valuable metal from gold slime

Info

Publication number: CN1163314A
Application number: CN96116082A
Authority: CN
Inventors: 纪寿昌; 王振忠; 王福祥; 黄志诚; 张侠; 王永选; 李腾山; 于汉芳
Original assignee: BEIJIE GOLD MINE ZHAOYUAN
Current assignee: BEIJIE GOLD MINE ZHAOYUAN
Priority date: 1996-11-21
Filing date: 1996-11-21
Publication date: 1997-10-29
Anticipated expiration: 2016-11-21
Also published as: CN1043787C

Abstract

Technologically, the said process features that it processes gold slime through four technological steps of extracting copper and zinc, extracting silver and lead, alkali soaking and aqua regia lixiviation of gold. Compared with available pyrometallurgical process, the said one has the advantages of high metal recovering rate, low cost, less slag amount and short working period, etc. And it may be widely used in gold slime smelting process.

Description

Process method for extracting valuable metal from gold mud

The invention relates to a process method for extracting valuable metals from gold mud.

The existing smelting process of the gold mud generally adopts a direct smelting method to extract valuable metals such as gold, silver and the like. This pyrometallurgical smelting comprises: drying gold mud, smelting in a converter, electrolyzing alloy gold, acid boiling electrolytic anode mud, smelting and casting ingots by a gold powder electric furnace and the like. The method has the defects of low recovery rate of gold and silver, difficult treatment of smelting slag, long operation time and the like.

The invention aims to provide a process method for extracting valuable metals from gold mud so as to overcome the defects in the prior art.

The technical scheme of the invention is realized as follows: a process method for extracting valuable metals from gold mud is completed according to the following process steps: firstly, removing copper and zinc, soaking gold mud in sulfuric acid solution with the concentration of 30-60% at the temperature of 60-100 ℃ according to the liquid-solid ratio of 2-6: 1 for 1-3 hours, adding an oxidant into the soaked gold mud according to the ratio of 1-2: 10, and replacing the soaking solution with a reducing agent to recover copper. This step is represented by the following chemical reaction equation: in the step, oxides and sulfides of zinc and copper enter the pickle liquor in a state of easy salt dissolution under the action of acid, the copper and the sulfides are further oxidized by an oxidant and enter the liquor, sulfur generated in the reaction process is further oxidized by sulfuric acid and oxygen, and the copper in the pickle liquor is replaced and recovered by a reducing agent; the second step is that: the silver and lead are removed, and the silver and lead are removed,soaking the leaching residue after copper and zinc removal by using a nitric acid solution with the temperature of 60-100 ℃ and the concentration of 25-65% according to the liquid-solid ratio of 2-6: 1, wherein the leaching time is 1-4 hours each time, the leaching frequency is 2-4 times, adding hydrochloric acid with equivalent weight into the nitric acid leaching solution to produce AgCL precipitate, and then replacing silver by using a reducing agent. This step can be represented by the following chemical equation:

the third step: soaking gold in aqua regia, soaking gold in aqua regia soaking solution with water-aqua regia ratio of 1-4: 1 at 60-100 deg.C for 2-4 times of 2-4 hr each time, adding nitrate removing agent into the aqua regia soaking solution to remove nitric acid, reducing with reducing agent to obtain gold powder, drying, and casting ingot. The chemical reaction formula of the step is as follows:

between the second and third steps, alkaline leaching can be carried out to further remove silver and lead while destroying silicic acid that affects the filtration. Soaking the leaching residue after nitric acid leaching with alkali liquor of water, caustic soda and soda ash in a liquid-solid ratio of 2-5: 1 at 60-100 ℃ for 0.5-2 hours in an alkali liquor of 100: 8-15: 1-3, and performing nitric acid leaching under the same conditions to dissolve and remove PbCO generated by alkali leaching after the alkali leaching is finished₃And Ag₂CO₃The reaction of this step is:

in each of the above process steps, the oxidant may be manganese dioxide, the reductant may be iron powder, and the nitrate-removing agent may be urea.

Compared with the prior art, the invention has the following advantages and positive effects: firstly, the method comprises the following steps: the recovery rate of gold reaches 99.99%, the recovery rate of silver reaches 99.98%, the recovery rates are respectively 0.99% and 27.98% higher than that of pyrometallurgical gold melting, and in addition, the recovery rate of copper is increased by 80% compared with pyrometallurgical gold melting; secondly, through economic accounting, the cost of the method is 5 yuan lower than that of every two gold prepared by a fire method; thirdly, the slag discharge is obviously reduced, the loss of valuable metals is reduced, and the working period is shortened by 10 days; fourthly, the method reduces the labor intensity of workers, improves the working environment and reduces the environmental pollution degree.

The invention is further illustrated by the following examples:

example 1, first, removing copper and zinc, soaking gold mud in 40% sulfuric acid at 70 ℃ for 3 hours, adding manganese dioxide to the gold mud after soaking according to the ratio of 1: 10, and adding iron powder to the soaking solution to replace and recover copper; the second step of silver and lead removal, namely soaking the leaching residue after copper and zinc removal by using a nitric acid solution with the concentration of 35% at 70 ℃ according to the liquid-solid ratio of 3: 1, wherein the leaching time is 3 hours each time, the leaching frequency is 4 times, adding hydrochloric acid with equivalent weight into the solution after the nitric acid leaching to generate AgCL precipitate, simultaneously returning the generated nitric acid for reuse, replacing silver by using a reducing agent, the third step of alkaline leaching, further removing silver and lead, and simultaneously destroying silica gel influencing filtration, soaking the leaching residue after the nitric acid leaching by using an alkali solution with the ratio of water, caustic soda and soda of 100: 8: 1 at 70 ℃, soaking the leaching residue after the nitric acid leaching by using the liquid-solid ratio of 2: 1, wherein the leaching time is 1 hour, and then performing one-time nitric acid leaching under the same conditions after the alkaline leaching to dissolve and remove PbCO generated by the alkaline leaching₃And Ag₂CO₃(ii) a And step four, soaking gold in aquaregia, soaking gold in the obtained leaching residue at the liquid-solid ratio of 3: 1 by using aqua regia soaking liquid with the ratio of water to aqua regia of 1: 1 at the temperature of 70 ℃, adding urea into the aqua regia soaking liquid to remove nitric acid, reducing by using a reducing agent to produce gold powder, and carrying out drying and ingot casting. The entire method is completed.

Example 2 the method of the present invention can be carried out by adjusting the indexes within the ranges of the technical parameters and the mixture ratios specified in the claims by the procedure described in example 1, and the same effects can be obtained.

Claims

1. A process method for extracting valuable metals from gold mud is characterized by comprising the following steps:

the first step is as follows: removing copper and zinc, soaking gold mud in sulfuric acid solution with the concentration of 30-60% at the temperature of 60-100 ℃ according to the liquid-solid ratio of 2-6: 1 for 1-3 hours, adding an oxidant into the soaked gold mud according to the ratio of 1-2: 10, and replacing the soaking solution with a reducing agent to recover copper;

the second step is that: removing silver and lead, soaking the leaching residue after copper and zinc removal by using a nitric acid solution with the temperature of 60-100 ℃ and the concentration of 25-65% according to the liquid-solid ratio of 2-6: 1, wherein the leaching time is 1-4 hours each time, the leaching frequency is 2-4 times, adding hydrochloric acid with equivalent weight into the nitric acid leaching solution to produce AgCL precipitate, and replacing metallic silver by using a reducing agent;

the third step: soaking gold in aqua regia, soaking gold in aqua regia soaking solution with water-aqua regia ratio of 1-4: 1 at 60-100 deg.C for 2-4 times of 2-4 hr each time, adding nitrate removing agent into the aqua regia soaking solution to remove nitric acid, reducing with reducing agent to obtain gold powder, drying, and casting ingot.

2. The process of claim 1, wherein alkaline leaching is performed between the second step and the third step, the leaching residue after nitric acid leaching is soaked in an alkaline solution with a ratio of water, caustic soda and soda ash of 100: 8-15: 1-3 at 60-100 ℃ for 0.5-2 hours in a liquid-solid ratio of 2-5: 1, and the alkaline leaching is performed again in the same conditions as the second step to dissolve and remove PbCO generated by alkaline leaching₃And Ag₂CO₃。

3. The process for extracting valuable metals from gold mud as claimed in claim 1 or 2, wherein the oxidant added in the copper and zinc removing process is manganese dioxide.

4. The process of claim 1 or 2, wherein the reducing agent used in the first and second steps is iron powder.

5. The process of claim 3, wherein the reducing agent used in the first and second steps is iron powder.

6. The process for extracting valuable metals from gold mud as claimed in claim 1 or 2, wherein the nitrate-removing agent used in the third step is urea.

7. The process of claim 3, wherein the nitrate-removing agent used in the third step is urea.

8. The process of claim 4, wherein the nitrate-removing agent usedin the third step is urea.