CN1119678A - Method for recovering silver, gold, antimony, copper and lead from lead anode mud - Google Patents

Abstract

A method for recovering silver, gold, antimony, copper and lead from lead anode slime uses hydrochloric acid to leach out antimony and copper, uses sodium chlorate-hydrochloric acid-sodium chloride to leach out gold and uses ammonia to leach out spongy silver. Its leaching time is short, leaching effect is good, acid consumption is low and cost is low, and its direct-yield rate is up to above 96% and silver content is 99.3%. Said process can directly obtain analytically pure silver nitrate.

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 non-ferrous metals such as lead, copper, nickel and other anode slimes has become an important source of silver. For many years, my country has been using traditional pyrometallurgy to treat such anode slimes. The pyrotechnic process has the characteristics of large processing capacity and strong adaptability of raw materials. However, it also has disadvantages such as long process flow, more slag returning, large investment, and long production cycle. And in the process of pyro-reduction smelting and oxidation refining, a large amount of flue gas such as arsenic, lead, antimony and selenium is discharged, which seriously pollutes the environment. In recent years, many domestic scientific research institutes and smelters have developed a method to treat anode slime by wet method. The process is relatively simple, with less intermediate products, less investment in plant construction, and quick capital turnover, which can effectively and comprehensively utilize useful metals in anode slime. . Such as Chinese patent 90109944.9 discloses a kind of " method for producing silver nitrate, reclaiming copper, lead, antimony " by lead anode slime, is to leach the filter residue after nitric acid leaching with hydrochloric acid, and then sink lead with sulfuric acid, hydrolyze the hydrochloric acid leaching solution, The filter residue obtained by alkali washing and hydrolysis is subjected to silver precipitation with hydrochloric acid, ammonia leaching, complexation, reduction, etc. It also has complex procedures, large consumption of nitric acid, high cost, and low silver recovery.

The purpose of the present invention is to aim at the deficiencies that exist in the above-mentioned background technology, and introduce a kind of acid consumption is little, cost is low, the recovery rate of silver is higher, pollution is little, and can reclaim silver, gold, antimony from all kinds of lead anode slime , copper, and lead methods.

The object of the present invention is achieved by the following technical solutions: the method includes the preparation process of leaching copper with hydrochloric acid and leaching antimony, and the concrete process is:

1. Use hydrochloric acid with a liquid-solid ratio of 3:1-6:1, 3N-5.5N to leaching at 60-90°C for 1-2 hours to remove copper and antimony in the anode slime, recover antimony by hydrolysis, and use iron filings replace copper;

2. Add sodium chlorate with a residue weight of 3-10% to the filter residue, and use a liquid-solid ratio of 3:1-5:1, 0.3N ~1N hydrochloric acid and sodium chloride with slag weight of 2 ~ 12% are leached at 60 ~ 90 ° C for 1 ~ 3 hours and then filtered, and the filtrate is reduced with oxalic acid, ferric sulfite or sulfur dioxide to produce sponge gold;

3. The sodium chlorate leaching residue is leached twice with liquid-solid ratio of 3:1-6:1, 3N-5N ammonia water at 20-60°C for 1-3 hours and then filtered, and the excess of filtrate is 1.2-2 times Sponge silver can be obtained by reduction of activated carbon or activated aluminum.

Accompanying drawing is process flow chart of the present invention.

The technical solution of the present invention will be further described in conjunction with the accompanying drawings.

1. Hydrochloric acid leaching of antimony and copper

Antimony in lead anode slime mainly exists in the form of metal antimony and antimony trichloride, and only a small amount exists in the form of antimony alloy. Add hydrochloric acid with a liquid-solid ratio of 5:1 and a concentration of 4N to the lead anode slime and leach at a temperature of 75-90° C. for 1-1.5 hours. During the leaching process, antimony trioxide reacts with hydrochloric acid to form antimony trichloride solution such as

Metallic antimony also reacts with hydrochloric acid to form a solution of antimony trichloride, such as

Copper in anode slime mainly exists as metallic copper, and partly exists as basic copper carbonate. Copper and basic copper carbonate react with hydrochloric acid to form cuprous chloride solution, such as

In this process, more than 95% of antimony and copper are leached, and the antimony and copper chloride are combined and separated from the silver-containing filtrate by vacuum filtration, and the leaching rate of silver is lower than 1%.

2. Chloride gold leaching

After leaching antimony and copper with hydrochloric acid, the main components in the leaching residue are silver, gold, and lead compounds. Add 4-6% sodium chlorate in excess of slag weight to the hydrochloric acid medium, and then add 6-10% slag weight The gold is leached by sodium chloride and hydrochloric acid with a concentration of 0.5N-0.6N and a liquid-solid ratio of 4:1, the leaching temperature is 75-85° C., and the leaching time is 1.5-2.5 hours. During this process the following reactions take place:

Sodium chlorate reacts with hydrochloric acid to generate hypochlorous acid, which immediately decomposes to generate active oxygen to oxidize gold and silver. At this time, gold forms complex ions and enters the solution, and the oxidized silver combines with oxygen and chlorine to form silver chloride with a very low solubility product, which precipitates into the slag. Since the concentration of industrial sodium chloride is about 40g/L and the concentration of hydrochloric acid medium is 0.5N-0.6N during gold chlorination leaching, it is difficult to form [AgCl ₂ ] ^- , so silver is hardly leached. During chlorination, the copper content in the slag is further reduced. The purpose of its chlorination is to convert almost all of the silver into silver chloride.

3. Ammonia leaching process

After the chlorination treatment, most of the silver in the slag is converted into silver chloride, and the lead is converted into lead dichloride. At this time, ammonia water with a concentration of 3N to 4N and a liquid-solid ratio of 5:1 is added to the slag for secondary Stage ammonia leaching, the leaching temperature is 40-55°C, and the time is 1.2-1.8 hours. The filter residue after ammonia leaching for the first time is carried out secondary ammonia leaching again, to ensure that silver chloride is completely converted into ammonia silver complex ion, its reaction is as follows:

Since lead dichloride does not complex with ammonia water, the ammonia immersion solution is Ag(NH ₃ ) ₂ ⁺ .

4. Silver reduction process

The Ag(NH ₃ ) ₂ produced after the complexation reaction of silver chloride is reduced in a stainless steel reactor with an excess of 1.5 times of dechlorination agent such as activated carbon or activated aluminum, and the following reactions occur during the reduction process:

The sponge silver obtained after reduction is filtered and then washed with double distilled water, and after drying, it contains More than 99.0% silver sponge silver.

After the sponge silver is washed, react with reagent grade silver nitrate to generate silver nitrate, the reaction formula is as follows:

Add 11-13 liters of 65% reagent-grade silver nitrate to 20 liters of twice-distilled water in the reaction kettle, react with 8-11 kg of sponge silver, evaporate, crystallize, filter, and dry to obtain reagent-grade silver nitrate .

The results of the pilot test are shown in the table below: Materials Material weight Kg Filtrate L Filter residue Kg Slag grade% Solution content g/l Leaching rate% Recovery rate Cu Sb Ag Cu Sb Ag Cu Sb Ag Anode slime 100 6.1 9.50 16.40 Copper leaching antimony slag 43.68 0.04 0.34 37.60 Copper Immersion Antimony Solution 490 12.41 19.08 not detected 99.68 98.41 Chlorinated slag 40 0.04 0.31 Chlorinated solution not detected Ammonia leaching residue 25.31 Pb62.10 0.1 Ammonia infusion 470 33.5 Sponge silver 15.9 99.30 96.27 reducing solution 460 0.1

The invention overcomes the shortcomings in the background technology, uses hydrochloric acid as the leaching agent to improve the leaching effect of copper and antimony, and does not need to add an oxidant, and can effectively separate copper and antimony from silver, gold and lead. In the sodium chlorate-hydrochloric acid-sodium chloride gold immersion process, the hypochlorous acid generated after the action of sodium chlorate and hydrochloric acid immediately decomposes into active oxygen, and oxidizes gold and silver. At this time, gold forms complex ions and enters the solution. And silver combines with oxygen and chlorine to form silver chloride precipitate with very low solubility product, which exists in the slag and prepares for ammonia complexed silver. The silver ammonium complex produced after silver chloride is complexed is reduced to sponge silver with 1.5 times excess activated carbon or activated aluminum, and the direct recovery rate of silver is over 96%. Silver nitrate of analytical grade or industrial grade can be obtained directly by adding silver nitrate to silver sponge after washing. The method has short leaching time, good leaching effect, low acid consumption, low cost, less pollution, and the silver content of sponge silver can reach more than 99.3%, and can produce analytically pure silver nitrate that meets GB670-86 standards, and is suitable for various Treatment of lead-like anode slime.

Claims (4)

1. A method for recovering silver, gold, antimony, copper and lead from lead anode slime comprises the step of leaching antimony by using hydrochloric acid to leach copper, and is characterized in that:

1.1, 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 antimonyin 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 the sodium chlorate leaching residue for 1-3 hours by using ammonia water with the liquid-solid ratio of 3: 1-6: 1 and the liquid-solid ratio of 3N-5N at 20-60 ℃, filtering, and adding excessive activated carbon or activated aluminum with the amount of 1.2-2 times into the filtrate to reduce to obtain the sponge silver.

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 ℃.

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