CN1114361A

CN1114361A - Method for recovering Ag, Au, Sb, Cu and Pb from Pb anode slime

Info

Publication number: CN1114361A
Application number: CN94107754A
Authority: CN
Inventors: 王广文; 张文钲; 丁育民
Original assignee: SHENHUA METAL MATERIAL INST SHAANXI
Current assignee: SHENHUA METAL MATERIAL INST SHAANXI
Priority date: 1994-06-28
Filing date: 1994-06-28
Publication date: 1996-01-03

Abstract

The process for recovering Ag, Au, Sb, Cu and Pb from Pb anode slime features use of hydrochloric acid to extract Sb and Cu, sodium chlorate-hydrochloric acid-sodium chloride to extract Au and ammonia to extract sponge Ag with Ag content of 99.3% for direct production of analytically pure silve nitrate. Its advantages include shorter extraction period, high extraction effect, low cost, high direct yield of sponge silver up to over 96% and low pollution.

Description

Method for recovering silver, gold, antimony, copper and lead from lead anode slime

The invention relates to a method for recovering silver, gold, antimony, copper and lead from lead anode slime, belonging to the technical field of hydrometallurgy.

The recovery of associated silver from anode slime of nonferrous metals such as lead, copper, nickel and the like has become an important source of silver, and China always adopts the traditional pyrometallurgical treatment of the anode slime for many years. The pyrogenic process has the characteristics of high processing capacity, strong raw material adaptability and the like. But also has the defects of long process flow, more return slag, large investment, long production period and the like. And a large amount of flue gas such as arsenic, lead, antimony, selenium and the like is discharged in the process of reducing smelting and oxidizing refining by a pyrogenic process, so that the environment is seriously polluted. In recent years, a plurality of scientific research institutes and smelting plants in China research out the method for treating the anode mud by the wet method, the process flow is simpler, the number of intermediate products is less, the investment for building the plant is less, the capital turnover is fast, and the useful metals in the anode mud can be effectively and comprehensively utilized. For example, chinese patent 90109944.9 discloses a method for preparing silver nitrate and recovering copper, lead and antimony from lead anode slime, which comprises leaching the filter residue after nitric acid leaching with hydrochloric acid, precipitating lead with sulfuric acid, hydrolyzing hydrochloric acid leaching solution, washing the filter residue obtained by hydrolysis with alkali, precipitating silver with hydrochloric acid, ammonia leaching, complexing, reducing, etc. It also has the defects of complex working procedure, large consumption of nitric acid, high cost, low recovery rate of silver and the like.

The invention aims to provide a method for recovering silver, gold, antimony, copper and lead from various lead anode slime, which has the advantages of low acid consumption, low cost, high silver recovery rate and low pollution and can overcome the defects in the prior art.

The purpose of the invention is realized by the following technical solution: the method is carried out according to the following steps in sequence:

1. leaching for 1-2 hours at 60-90 ℃ by using hydrochloric acid with the liquid-solid ratio of 3: 1-6: 1 and the 3N-5.5N, removing copper and antimony in the anode mud, recovering antimony through hydrolysis, and replacing copper with scrap iron;

2. adding sodium chlorate accounting for 3-10% of the weight of the residue into the filter residue, leaching the filter residue for 1-3 hours at 60-90 ℃ by using hydrochloric acid accounting for 0.3-1N and sodium chloride accounting for 2-12% of the weight of the residue in a liquid-solid ratio of 3: 1-5: 1, filtering, and reducing the filtrate by using oxalic acid or ferric sulfite or sulfur dioxide to obtain sponge gold;

3. leaching the sodium chlorate leaching residue for 1-3 hours at 20-60 ℃ by using 3-5N ammonia water with the liquid-solid ratio of 3: 1-6: 1, filtering, adding 1.2-2 times of excessive hydrazine hydrate into the filtrate, and reducing to obtain sponge silver, wherein the filter residue is lead dichloride containing 56-70% of lead.

4. Dissolving sponge silver in reagent-grade nitric acid, adsorbing with dechlorinating agent such as activated carbon or activated aluminum, filtering, evaporating, crystallizing, filtering, and oven drying to obtain analytically pure silver nitrate.

The attached drawing is a process flow chart of the invention.

The technical solution of the present invention will now be further described with reference to the accompanying drawings.

First, hydrochloric acid soaks antimony, copper

The antimony in the lead anode slime is mainly in the form of metallic antimony and antimony trioxide, and only a small amount of antimony exists in the form of antimony alloy. Adding hydrochloric acid with the liquid-solid ratio of 5: 1 and the concentration of 4N into the lead anode slime, and leaching for 1-1.5 hours at the temperature of 75-90 ℃. In the leaching process, antimony trioxide reacts with hydrochloric acid to form an antimony trichloride solution such as

Metallic antimony also reacts with hydrochloric acid to form an antimony trichloride solution, e.g.

The copper in the anode slime is mainly present as metallic copper and partly as basic copper carbonate, the copper and basic copper carbonate react with hydrochloric acid to form cuprous chloride solution, e.g. copper chloride

In the process, more than 95 percent of antimony and copper are leached, and antimony and copper chloride are separated from silver-containing filter residue through vacuum filtration, wherein the leaching rate of silver is lower than 1 percent.

Chlorination gold leaching

After antimony and copper are leached by hydrochloric acid, the leaching residue mainly contains silver, gold and lead compounds, sodium chlorate accounting for 4-6% of the weight of the residue is added into hydrochloric acid medium, sodium chloride accounting for 6-10% of the weight of the residue and hydrochloric acid with the concentration of 0.5-0.6N and the liquid-solid ratio of 4: 1 are added to leach gold, the leaching temperature is 75-35 ℃, and the leaching time is 1.5-2.5 hours. The following reactions take place in the process:

the action of sodium chlorate and hydrochloric acid produces hypochlorous acid, which is immediately decomposed to produce active oxygen to oxidize gold and silver. At the moment, gold forms complex ions to enter the solution, and oxidized silver is combined with chlorine to generate silver chloride precipitate with low solubility product to enter slag. The concentration of industrial sodium chloride is about 40g/L and the concentration of hydrochloric acid medium is 0.5N-0.6N when gold leaching is carried out by chlorination, so that the [ AgCl]is difficult to form₂]So silver is hardly leached out. During chlorination, the copper content in the slag is further reduced. The purpose of chlorination is to convert substantially all of the silver to silver chloride.

Three, ammonia leaching process

After chlorination, most of silver in the slag is converted into silver chloride, lead is converted into lead dichloride, ammonia water with the concentration of 3-4N and the liquid-solid ratio of 5: 1 is added into the slag for secondary ammonia leaching, the leaching temperature is 40-55 ℃, and the time is 1.2-1.8 hours. And (3) carrying out secondary ammonia leaching on the filter residue after the primary ammonia leaching to ensure that the silver chloride is completely converted into silver-ammonia complex ions, wherein the reaction is as follows:

since the lead dichloride is not complexed with the ammonia water, the ammonia leaching solution is Ag (NH)₃)₂ ⁺And the filtrate is lead dichloride containing 56-70% of lead.

Four, silver reduction process

Ag (NH) produced after complexing reaction of silver chloride₃)₂Reducing hydrazine hydrate (also called hydrazine hydrate) with 1.5 times excess in a stainless steel reaction kettleReaction under

Filtering the reduced sponge silver, washing the sponge silver by secondary distilled water, and drying the sponge silver to obtain the sponge silver with the silver content of more than 99.0 percent.

The sponge silver is washed and then reacts with reagent-grade nitric acid to generate silver nitrate, and the reaction formula is as follows:

adding 11-13 liters of 65% reagent-grade nitric acid into 20 liters of secondary distilled water in a reaction kettle to react with 8-11 kilograms of sponge silver, adsorbing impurities such as chloride ions in the solution by dechlorinating agents such as activated carbon or activated aluminum, and evaporating, crystallizing, filtering and drying to obtain the reagent-grade silver nitrate.

The results of the pilot test are shown in the following table:

name of material	Weight of material Kg	Filtrate L	Filtering residue Kg	Grade of slag (%)			Content of solution (%)				Leaching rate (%)		Recovery (%)
				Grade of slag (%)			Content of solution (%)				Leaching rate (%)		Recovery (%)		Cu	Sb	Ag	Au (g/r)	Cu	Sb	Ag	Au	Cu	Sb	Ag	Au
				Anode mud	100		6.1	9.5	16.4	252					Cu	Sb	Ag	Au (g/r)	Cu	Sb	Ag	Au	Cu	Sb	Ag	Au
Copper-leaching antimony slag			43.7	Anode mud	100		6.1	9.5	16.4	252					0.04	0.34	37.6	538
Copper-leaching antimony slag			43.7	Copper and antimony leaching solution		490					12.4	19.1			0.04	0.34	37.6	538									99.7	98.4
Chlorination slag			40	Copper and antimony leaching solution		490					12.4	19.1			0.04	0.31		21									99.7	98.4
Chlorination slag			40	Chlorination solution		380								0.64	0.04	0.31		21											96.5
Ammonia leaching residue			25.3	Chlorination solution		380								0.64	Pb 62.1		0.1												96.5
Ammonia leaching residue			25.3	Ammonia leaching solution		470							33.5		Pb 62.1		0.1
Sponge silver	15.9			Ammonia leaching solution		470							33.5				99.3								96.3
Sponge silver	15.9			Reducing liquid		460							0.1				99.3								96.3

The invention overcomes the defects in the background technology, improves the leaching effect of copper and antimony by using hydrochloric acid as a leaching agent, does not need to add an oxidant, and can effectively separate the copper and the antimony from silver, gold and lead. In the process of leaching gold by sodium chlorate-hydrochloric acid-sodium chloride, hypochlorous acid generated after the action of sodium chlorate and hydrochloric acid is immediately decomposed into active oxygen, gold and silver are oxidized, gold forms complex ions and enters the solution, crude gold is reduced by ferric sulfite, the recovery rate of gold is 96.5%, silver and chlorine are combined to generate silver chloride precipitate with low solubility product, and the silver chloride precipitate exists in slag and is ready for ammine complexing silver. And reducing the silver-ammonia complex generated after complexing the silver chloride into sponge silver by using hydrazine hydrate which is excessive by 1.5 times, wherein the direct recovery rate of the silver is more than 96 percent, and the ammonia leaching residue is lead dichloride containing 56 to 70 percent of lead. The sponge silver is washed, dissolved in nitric acid, and adsorbed and filtered by dechlorinating agent such as active carbon or active aluminum to obtain analytically pure or industrial pure silver nitrate. The method has the advantages of short leaching time, good leaching effect, low acid consumption, low cost, less pollution, capability of producing the silver nitrate of analytical pure grade meeting the GB 670-86 standard, and capability of producing the silver nitrate of the sponge silver with the silver content of more than 99.3 percent, and is suitable for treating various lead anode slime.

Claims

1. A method for recovering silver, gold, antimony, copper and lead from lead anode slime is characterized by comprising the following steps in sequence:

1.1, leaching for 1-2 hours at 60-90 ℃ by using hydrochloricacid with the liquid-solid ratio of 3: 1-6: 1 and the 3N-5.5N, removing copper and antimony in anode mud, recovering antimony through hydrolysis, and replacing copper with scrap iron;

1.2 adding sodium chlorate accounting for 3-10% of the weight of the residue into the filter residue, leaching the filter residue for 1-3 hours at 60-90 ℃ by using hydrochloric acid accounting for 0.3-1N and sodium chloride accounting for 2-12% of the weight of the residue in a liquid-solid ratio of 3: 1-5: 1, filtering, and reducing the filtrate into sponge gold by using oxalic acid, ferric sulfite or sulfur dioxide;

1.3, leaching sodium chlorate leaching residue for 1-3 hours at 20-60 ℃ for two times by using ammonia water with a liquid-solid ratio of 3: 1-6: 1 and 3N-5N, filtering, adding 1.2-2 times of excessive hydrazine hydrate into filtrate, reducing to obtain sponge silver, and obtaining filter residue which is lead dichloride containing 56-70% of lead;

1.4 dissolving sponge silver in reagent-grade nitric acid, adsorbing and filtering with dechlorinating agent such as activated carbon or activated aluminum, evaporating, crystallizing, filtering, and oven drying to obtain analytically pure silver nitrate.

2. The method as claimed in claim 1, wherein the liquid-solid ratio of the hydrochloric acid leaching in 1.1 is 4: 1-6: 1, the concentration is 4N-5N, and the leaching temperature is preferably 75-90 ℃.

3. The method as set forth in claim 1, wherein the weight of said sodium chlorate in 1.2 is 5-10% of the weight of the residue, the concentration of hydrochloric acid is 0.5-0.8N, the liquid-solid ratio is 3.5: 1-4.5: 1, the amount of sodium chloride is 4-11% of the weight of the residue, the leaching temperature is 70-90 ℃, and the leaching time is 1-2.5 hours.

4. The method according to claim 1, wherein the ammonia water concentration of 1.3 is 3 to 4N, the liquid-solid ratio is 4: 1 to 5: 1, and the ammonia leaching is carried out at 30 to 55 ℃.