Method for preferentially extracting gold and silver from lead anode slime

Abstract

The invention provides a method for preferentially extracting gold and silver from lead anode slime, and relates to the technical field of precious metal recovery, firstly, silver, antimony and other valuable metals in the lead anode slime are leached into a solution through catalytic oxidation leaching in the presence of a protective agent, and gold is enriched in residues; then, silver is selectively precipitated from the leachate, and silver precipitation residues and a valuable metal solution are obtained; and finally, valuable metals in the solution are recovered by adding a neutralizer and a precipitator, the obtained leaching mother liquor can be returned for leaching after being supplemented with hydrochloric acid, and the valuable metal precipitates are used for recovering antimony and bismuth. The method changes the traditional lead anode slime treatment thinking of first impurity removal and second refining, has the characteristics of high gold and silver direct recovery rate (greater than 99.5%), high reaction speed (total consumed time is less than 1 h), low cost and no generation of waste residue and wastewater, and is expected to solve the problems of long gold and silver recovery process, low direct recovery rate, capital overstock and difficult treatment of arsenic and antimony-containing smoke in the existing lead anode slime treatment method. The method has remarkable economic and environmental benefits and a good application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of precious metal recovery, in particular to a method for preferentially extracting gold and silver from lead anode slime. BACKGROUND

[0002] Lead anode slime is generated in the electrolysis process of lead smelting, and contains precious metals and antimony, bismuth, arsenic, lead, copper, tellurium, selenium, tin, etc. Most of the gold and silver in the lead smelting system is enriched in the anode slime. The content of gold in the lead anode slime is about 0.002%~0.8%, and the content of silver is about 0.1~25%. Gold and silver account for 60%~90% of the value of lead anode slime, and are important raw materials for gold and silver extraction, and also important profit sources for lead smelting plants. At present, the strategic position and application value of gold and silver are continuously rising, and are increasingly concerned. Therefore, improving the gold and silver recovery efficiency of lead anode slime has far-reaching significance for enhancing the resource guarantee capacity of China.

[0003] The widely used method for treating lead anode slime in the industry is "reduction smelting-oxidation smelting-gold and silver refining", which has strong processing capacity and low cost, but has problems such as high energy consumption, large loss of gold and silver in slag, arsenic-containing dust pollution, and poor working environment. Although some researches have improved equipment and process, they have not solved the problem of loss of gold and silver in a large amount of smelting slag and dust. Wet treatment usually uses the chemical inertness of precious metals, and first removes valuable metals through a series of pretreatments to obtain precious metal concentrates, and then refines the precious metals. The controlled electrochlorination leaching-chlorination gold separation process has problems of long pretreatment time and loss of Ag in leaching solution, and the alkali leaching arsenic removal-acid leaching impurity removal process has problems of long process and high reagent cost.

[0004] The current treatment method places the extraction of gold and silver at the end of the process, which results in long gold and silver recovery process (several days), low direct recovery rate of gold and silver (Au~97%, Ag~92%), and serious capital accumulation. Therefore, it is of great significance to develop a method for preferentially and efficiently extracting gold and silver from lead anode slime. SUMMARY

[0005] The present application solves the problems of long gold and silver recovery process, low direct recovery rate of gold and silver, serious capital accumulation, high energy consumption, arsenic-containing dust pollution, and poor working environment in the existing lead anode slime treatment technology by improving the process.

[0006] Specifically, a method for preferentially extracting gold and silver from lead anode slime comprises: S1, catalytic oxidation leaching: adding protective agent to the solution containing hydrochloric acid, chloride salt and catalytic metal ions, mixing with lead anode slime, and then passing in oxidizing gas for leaching. After leaching, filter to obtain gold-rich residue and leaching solution. Without protective agent, gold leaching loss will occur. The chloride salt provides leaching agent and maintains selective oxidation of copper because the required Cl concentration is high. Without adding chloride salt, the system acidity will be too high.

[0007] S2, selective silver deposition: adding iodide to the leaching solution obtained in S1 to recover silver. After reaction, filter to obtain silver iodide residue and valuable metal solution. S3, hydrolysis / precipitation: adding neutralizing agent and precipitating agent to the valuable metal solution obtained in S2 in sequence to make the valuable metals in the solution precipitate, to obtain valuable metal precipitate and leaching mother liquor. The leaching mother liquor is supplemented with hydrochloric acid and then returned to catalytic oxidation leaching. The valuable metal precipitate is used to recover antimony and bismuth.

[0008] Preferably, the chloride salt in step S1 is one or more of sodium chloride, calcium chloride, and ammonium chloride. The catalytic metal ion is copper ion or cuprous ion. Specifically, copper chloride or cuprous chloride can be selected.

[0009] Preferably, the protective agent in step S1 is a metal or intermetallic compound, preferably metallic tellurium, metallic selenium, or tellurium selenide (wherein the ratio of selenium to tellurium can be any common ratio). The usage amount is greater than 0 and not more than 0.2% of the mass of the lead anode slime.

[0010] Preferably, the concentration of H + in the leaching solution in step S1 is 0.5-3 mol / L. The concentration of catalytic metal ion is 2-20 g / L. The total chlorine concentration adjusted by the chloride salt is 200-260 g / L. The reaction temperature is 80-100 ℃. The liquid-solid ratio is 8:1-20:1. Through this process condition, gold can be enriched by more than 30 times in one step, and the reaction time is less than 1 h.

[0011] Preferably, the oxidizing gas in step S1 is air and / or oxygen. The gas flow rate is sufficient to meet the requirements of the oxidation reaction, without special requirements.

[0012] Preferably, the leaching rate of silver, antimony, bismuth, arsenic, and lead in step S1 is higher than 99.5%. The leaching rate of gold is lower than 0.5%. The residue rate (i.e. the ratio of the weight of the leaching residue to the weight of the raw material, which can reflect the gold enrichment multiple) is lower than 4%. The main component of the gold-rich residue is SiO2.

[0013] Preferably, the iodide in step S2 is one or more of sodium iodide, calcium iodide, zinc iodide, magnesium iodide, lead iodide, antimony iodide, and bismuth iodide.

[0014] Preferably, the amount of iodide used in step S2 is 1.1-1.3 times the molar amount of silver, the reaction temperature is 0-100 DEG C, and the reaction time is 0.5-1 h.

[0015] Preferably, the neutralizing agent used in step S3 is one or more of sodium hydroxide, ammonia, calcium hydroxide, calcium oxide, calcium carbonate, and water, preferably at least two of them, and more preferably at least one of sodium hydroxide, ammonia, calcium hydroxide, calcium oxide, and calcium carbonate is used in combination with water as the neutralizing agent; and the precipitating agent is one or more of sodium sulfide, sodium hydrosulfide, hydrogen sulfide, calcium sulfide, and ammonium sulfide.

[0016] Preferably, the end point pH value after adding the neutralizing agent in step S3 is 1.0-1.7, and the amount of the precipitating agent added is 1.05-1.2 times the total molar amount of the residual metals. By using such process conditions, it is possible to avoid too much hydrogen sulfide production due to too high acidity, and also avoid too low acidity which is not conducive to the reuse of the leaching solution.

[0017] The technical scheme provided by the embodiments of the present application has at least the following beneficial effects: The present application can preferentially extract gold and silver from lead anode slime, can enrich gold by more than 30 times in one step, takes less than 1 h, has a direct recovery rate of gold of more than 99.5%, and the obtained gold residue can be directly refined; the second step realizes selective extraction of silver, the impurity metal content in the silver deposition residue is less than 10%, and the direct recovery rate of silver is also more than 99.5%; fresh anode slime can be directly treated without pre-oxidation; the oxidizing agent consumed is air / oxygen, which improves the reaction efficiency while reducing the oxidation cost; the purified leaching mother liquor can be recycled to treat lead anode slime, avoids the generation of high-salt and heavy metal-containing waste liquid, and reduces the cost. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical scheme in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0019] Figure 1 is the process flow chart of the present application. DETAILED DESCRIPTION

[0020] The technical scheme in the present application will be described below.

[0021] In the embodiments of the present application, the words "exemplary", "for example", etc. are used to mean serving as an example, instance, or illustration, in no way implying any preference or relation by ABBREVIATION. Any embodiment or design scheme described in the present application as "exemplary" should not be interpreted as more preferred or having more advantages than other embodiments or design schemes. Rather, the word "exemplary" is used to present the concept in a specific manner. In addition, in the embodiments of the present application, the meaning expressed by "and / or" can be both, or can be either one of the two.

[0022] In the embodiments of the present application, "image" and "picture" can be used interchangeably at times. It should be pointed out that when the distinction is not emphasized, the meanings expressed are consistent. "The", "corresponding" and "corresponding" can be used interchangeably at times. It should be pointed out that when the distinction is not emphasized, the meanings expressed are consistent.

[0023] In the embodiments of the present application, sometimes the subscript such as W1 may be mistakenly used in the form of non-subscript such as W1. When the distinction is not emphasized, the meanings expressed are consistent.

[0024] In order to make the technical problems, technical schemes and advantages to be solved by the present application more clear, specific embodiments will be described in detail below.

[0025] The lead anode slime used in the embodiments at least includes: Au 60 g / t, Ag 4.09%, Sb 42.18%, Bi 17.12%, As 6.30%, Pb 13.65%, Te 0.28%, Se 0.03%. The main existence form of Au and Ag is elemental, and other metals are elemental and low-valence oxides.

[0026] Embodiment 1

[0027] A method for preferentially extracting gold and silver from lead anode slime, comprising: using water, concentrated hydrochloric acid, sodium chloride, and cuprous chloride to configure H +The leaching solution with concentration of 0.5 mol / L, cuprous ion concentration of 2 g / L and Cl concentration of 240 g / L, the amount of metallic tellurium added is 0.2% of the mass of the lead anode slime, oxygen is introduced for leaching the lead anode slime at 80 ℃ and liquid-solid ratio of 15:1, the time is 17 min, the leaching rates of silver and valuable metals are both higher than 99.5%, the leaching rate of gold is only 0.3% (i.e. the recovery rate of gold is 99.7%), the residue rate is 3.2%, and the enrichment multiple of gold in the residue is 31 times; immediately filtering and transferring the leaching solution to a new reactor, adding 1.1 times of the theoretical amount of sodium iodide, filtering after reaction at room temperature for 30 min, obtaining silver iodide and valuable metal solution, and the silver precipitation rate is 99.7%; adding sodium hydroxide 0.5 g / L to the valuable metal solution, adjusting the pH to ~1.5 by adding water, then adding sodium sulfide 8 g / L, filtering after reaction for 1 h, obtaining valuable metal residue and purified solution, and the valuable metal precipitation rate is all higher than 98%.

[0028] Example 2

[0029] A method for preferentially extracting gold and silver from lead anode slime, comprising: using water, concentrated hydrochloric acid, calcium chloride, copper chloride to configure H + The leaching solution with concentration of 3 mol / L, cupric ion concentration of 5 g / L and Cl concentration of 300 g / L, the amount of metallic selenium added is 0.1% of the mass of the lead anode slime, oxygen is introduced for leaching the lead anode slime at 85 ℃ and liquid-solid ratio of 12:1, the time is 16 min, the leaching rates of silver and valuable metals are both higher than 99.5%, the leaching rate of gold is only 0.4% (i.e. the recovery rate of gold is 99.6%), the residue rate is 3.3%, and the enrichment multiple of gold in the residue is 30 times; immediately filtering and transferring the leaching solution to a new reactor, adding 1.2 times of the theoretical amount of zinc iodide, filtering after reaction at room temperature for 30 min, obtaining silver iodide and valuable metal solution, and the silver precipitation rate is 99.9%; adding calcium oxide 6 g / L to the valuable metal solution, adjusting the pH to ~1.1 by adding water, then adding sodium sulfide 10 g / L, filtering after reaction for 1 h, obtaining valuable metal residue and purified solution, and the valuable metal precipitation rate is all greater than 98%.

[0030] Example 3

[0031] A method for preferentially extracting gold and silver from lead anode slime, comprising: using water, concentrated hydrochloric acid, ammonium chloride, copper chloride to configure H +The leaching solution with concentration of 2 mol / L, copper ion concentration of 15 g / L and Cl concentration of 260 g / L, the amount of tellurium selenide added is 0.01% of the mass of lead anode slime, under the conditions of 95 DEG C, liquid-solid ratio of 10:1, air is introduced to leach the lead anode slime for 15 min, the leaching rates of silver and valuable metals are all higher than 99.5%, the leaching rate of gold is only 0.4% (i.e. the recovery rate of gold is 99.6%), the residue rate is 2.9%, and the enrichment multiple of gold in the residue is 34 times; immediately filter and transfer the leaching solution to a new reactor, add 1.2 times of the theoretical amount of calcium iodide to the reactor, filter after reaction at normal temperature for 30 min, and obtain silver iodide and valuable metal solution, the silver precipitation rate is 99.9%; add calcium oxide 4 g / L to the valuable metal solution, adjust the pH to about 1.3 by adding water, then add sodium sulfide 9 g / L, filter after reaction at normal temperature for 1 h, and obtain valuable metal residue and purified solution, and the precipitation rates of valuable metals are all greater than 98%.

[0032] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited to this, any skilled person in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A process for preferential extraction of gold and silver from lead anode slime, characterized in that, The application relates to a method for recovering valuable metals from lead anode slime. The method comprises the following steps: S1, catalytic oxidation leaching: a protective agent is added into a solution containing hydrochloric acid, a chloride salt and catalytic metal ions, mixed with lead anode slime, and then an oxidizing gas is introduced for leaching, and after the leaching is completed, a gold-rich residue and a leaching solution are obtained by filtration; S2, selective silver deposition: iodide is added into the leaching solution obtained in S1 to recover silver, and after the reaction is completed, silver iodide residue and valuable metal solution are obtained by filtration; 2. The method of claim 1, wherein, S3, hydrolysis / precipitation: a neutralizing agent and a precipitating agent are sequentially added into the valuable metal solution obtained in S2 to make the valuable metals in the solution precipitate, and a valuable metal precipitate and a leaching mother liquor are obtained, the leaching mother liquor is supplemented with hydrochloric acid and then returned to the catalytic oxidation leaching, and the valuable metal precipitate is used for recovering antimony and bismuth.

3. The method of claim 1, wherein, The chloride salt in step S1 is one or more of sodium chloride, calcium chloride and ammonium chloride; and the catalytic metal ions are selected from copper ions and / or cuprous ions.

4. The method of claim 1, wherein, The concentration of H + in the leaching solution in step S1 is 0.5-3 mol / L, the concentration of catalytic metal ions is 2-20 g / L, the concentration of total chlorine adjusted by using a chlorine salt is 200-260 g / L, the reaction temperature is 80-100 ℃, and the liquid-solid ratio is 8:1-20:

1.

5. The method of claim 1, wherein, The protective agent in step S1 is a metal or an intermetallic compound.

6. The method of claim 1, wherein, In step S1, the leaching rates of silver, antimony, bismuth, arsenic and lead are all higher than 99.5%, the leaching rate of gold is lower than 0.5%, and the residue rate is lower than 4%.

7. The method of claim 1, wherein, The iodide in step S2 is one or more of sodium iodide, calcium iodide, zinc iodide, magnesium iodide, lead iodide, antimony iodide and bismuth iodide.

8. The method of claim 1, wherein, In step S2, the amount of the iodide is 1.1-1.3 times the molar amount of silver, the reaction temperature is 0-100 DEG C, and the reaction time is 0.5-1 h.

9. The method of claim 1, wherein, In step S3, the neutralizing agent is one or more of sodium hydroxide, ammonia, calcium hydroxide, calcium oxide, calcium carbonate and water; and the precipitating agent is one or more of sodium sulfide, sodium hydrosulfide, hydrogen sulfide, calcium sulfide and ammonium sulfide. In step S3, after the neutralizing agent is added, the final pH value is 1.0-1.7, and the amount of the precipitating agent is 1.05-1.2 times the total molar amount of the residual metals.

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