A method for recovering metal from high-arsenic copper-zinc solution

Abstract

The invention discloses a method for recovering metal from a high-arsenic copper-zinc solution, and relates to the technical field of metallurgy. The method comprises: adding a first alkaline reagent to a high-arsenic copper-zinc solution, controlling the pH value to 5.5-7, and performing a neutralization precipitation reaction to obtain a high-arsenic solution and a precipitated slag containing copper and zinc; adding an arsenic sulfide slag and a second alkaline reagent to the precipitated slag, controlling the pH value to 11-13, and performing an alkaline leaching and sulfidation reaction to obtain an alkaline leaching solution and a low-arsenic slag with an arsenic content of ≤0.5%; and acid leaching the low-arsenic slag to obtain copper sulfide and a zinc-containing solution. The method for recovering metal from a high-arsenic copper-zinc solution provided by the invention adopts a process combining neutralization precipitation and alkaline sulfidation, which can achieve a thorough separation of arsenic, copper and zinc, and the final metal recovery rate can reach more than 99.5%.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a method for recovering metal from a high-arsenic copper-zinc solution. Background Art

[0002] Using arsenic sulfide slag to recover copper from arsenic-containing copper solution is currently an ideal method. For example, CN 105603466 A (a method for efficiently separating and recovering copper and arsenic in copper electrolyte) uses arsenic sulfide slag to precipitate copper in copper electrolyte, thereby achieving copper-arsenic separation; CN116623000A (a method for wet combined treatment of arsenic-containing smoke and arsenic sulfide slag from copper smelting) uses arsenic sulfide slag to precipitate metallic copper from arsenic-containing smoke acid leaching solution, thereby achieving copper-arsenic separation. Wang Lei [1] Ma Yuncong [2] et al. studied the copper precipitation behavior and process of arsenic sulfide slag in copper smelting electrostatic dust collection acid leaching liquid, and explored the effects of conditions such as sulfur-copper ratio, initial sulfuric acid concentration, and reaction temperature. The above results all show that As2S3 can better convert copper in copper-arsenic solution into copper sulfide and arsenic into As2O3, thereby achieving copper-arsenic separation.

[0003] However, arsenic sulfide slag is generally composed of As2S3 and As2S5, and the As(III) / As(V) varies greatly depending on their sources. The above studies did not involve the reaction of As2S5, and there are some common problems: the separation of arsenic from valuable metals such as copper and zinc is not complete, which is mainly reflected in: (1) the precipitated copper sulfide slag has a high arsenic content and directly enters the pyrometallurgical recovery system, increasing the problem of arsenic accumulation; (2) other valuable metals such as nickel and zinc are enriched in the high arsenic solution and need to be further separated and recovered, which has a long process and high cost.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The object of the present invention is to provide a method for recovering metal from a high-arsenic copper-zinc solution.

[0006] The present invention is achieved in that:

[0007] In a first aspect, the present invention provides a method for recovering metal from a high-arsenic copper-zinc solution, comprising:

[0008] Adding a first alkaline reagent to a high-arsenic copper-zinc solution, controlling the pH value to be 5.5-7, and performing a neutralization precipitation reaction to obtain a high-arsenic solution and a copper-zinc-containing precipitated residue;

[0009] Adding arsenic sulfide slag and a second alkaline reagent to the precipitated slag, controlling the pH to 11-13, and performing an alkaline leaching and sulfidation reaction to obtain an alkaline leaching solution and a low-arsenic slag with an arsenic content of ≤0.5%;

[0010] The low-arsenic slag is subjected to acid leaching to obtain copper sulfide and a zinc-containing solution.

[0011] In an optional embodiment, the reaction temperature of the alkaline leaching vulcanization reaction is 45 to 95° C., and the reaction time is 1 to 4 hours;

[0012] Preferably, the amount of the arsenic sulfide slag is 1.01 to 1.2 times the theoretical amount.

[0013] In an optional embodiment, the precipitated slag is first slurried by adding water, and then the arsenic sulfide slag and the second alkaline reagent are added, wherein the solid-liquid ratio of the precipitated slag to the water is 1kg:5-7L.

[0014] In an optional embodiment, the alkaline leaching solution is returned to the neutralization precipitation reaction as an alkaline regulator to adjust the pH.

[0015] In an optional embodiment, the first alkaline reagent includes sodium hydroxide or aqueous ammonia, and the second alkaline reagent includes sodium hydroxide.

[0016] In an optional embodiment, the pH of the acid leaching is 1 to 4;

[0017] Preferably, the acid used for pickling is sulfuric acid.

[0018] In an optional embodiment, the zinc-containing solution is returned to the acid leaching step and circulated until the zinc content in the zinc-containing solution is ≥150 g / L and the arsenic is less than 0.2 g / L, so as to obtain a zinc solution to be electrolytically deposited, and the zinc solution to be electrolytically deposited is electrolytically deposited to obtain product electrolytic zinc.

[0019] In an optional embodiment, an iron reagent is added to the high-arsenic solution, the pH is controlled to be 5-7, and an iron salt arsenic precipitation reaction is performed to obtain a salt solution and arsenic iron slag;

[0020] Preferably, the high-arsenic solution contains less than 5 ppm copper and less than 1 ppm zinc;

[0021] Preferably, the iron reagent comprises ferric sulfate;

[0022] Preferably, the molar ratio of arsenic to iron in the high-arsenic solution and the iron reagent is 1:4-6.

[0023] In an optional embodiment, the salt solution is evaporated and crystallized to obtain product industrial salt, and the arsenic iron slag is treated to be harmless;

[0024] Preferably, the salt solution contains less than 1 ppm of arsenic.

[0025] In an optional embodiment, the high-arsenic copper-zinc solution includes a smoke acid leaching solution, a copper electrolysis solution, or an arsenic-containing copper solid waste acid leaching solution.

[0026] The present invention has the following beneficial effects:

[0027] The method for recovering metal from a high-arsenic copper-zinc solution provided by the present invention adopts a process combining neutralization precipitation and alkaline sulfidation, and can enrich more than 99.5% of copper and zinc in the precipitation slag during the neutralization precipitation process, and obtain a high-arsenic solution with copper less than 5ppm and zinc less than 1ppm; then, by alkaline sulfidation, the copper-zinc-containing precipitation slag reacts with arsenic sulfide slag in an alkaline system, and the amount of arsenic sulfide slag is controlled so that all copper in the precipitation slag is sulfided and converted into copper sulfide; the appropriate pH and reaction time are controlled so that the arsenic in the precipitation slag is converted into basic salt, and finally the arsenate and arsenite containing copper and zinc are fully reacted to release arsenic into the alkaline leaching solution, and the unreacted arsenic sulfide slag will also dissolve with the alkali, and finally low-arsenic slag is obtained, and the low-arsenic slag contains less than 0.5% of arsenic, and the alkaline leaching solution is returned to the copper removal leaching section to recover arsenic, and the overall process can achieve more than 99% separation of arsenic from copper and zinc. After acid leaching, the low-arsenic slag containing copper and zinc can obtain copper sulfide with low arsenic and zinc and zinc sulfate solution with low arsenic and copper, thus finally achieving a more thorough separation and recycling of arsenic, copper and zinc. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 The present invention provides a process flow chart of a method for recovering metal from a high-arsenic copper-zinc solution. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0031] CN105603466A and CN116623000A etc. believe that As2S3 can better convert copper in copper-arsenic solution into copper sulfide and arsenic into As2O3, thereby achieving copper-arsenic separation. The reaction mechanism is as follows:

[0032] As2S3+3CuSO4+4H2O=3CuS↓+2HAsO2+3H2SO4 (1)

[0033] As2S3+3H3AsO4=5HAsO2+3S+2H2O (2)

[0034] 2HAsO2=As2O3+H2O (3)

[0035] However, arsenic sulfide slag is generally composed of As2S3 and As2S5, and CN105603466A and CN116623000A do not involve the decoppering behavior of arsenic sulfide slag containing As2S5 in copper-containing arsenic solution. The present invention further studies the copper precipitation behavior of arsenic sulfide slag with high As(V) / As(III), and finds that in the acidic leaching solution system, in addition to the reactions of equations (1) to (3) above, the following reactions also occur:

[0036] As2S5+5CuSO4+8H2O=5CuS↓+2H3AsO4+5H2SO4(4)

[0037] As2S5+3H3AsO4=5HAsO2+5S+2H2O (5)

[0038] 2As2S5+2HAsO2=3As2S3+H2SO4 (6)

[0039] 3As2S3+10Cu 2+ +16H2O+H2SO4=10CuS↓+4H3AsO4+2HAsO2+20H + (7)

[0040] The copper precipitation reaction requires that the amount of arsenic sulfide is more than 1.3 times the theoretical copper precipitation amount (calculated by sulfur-copper ratio), the reaction temperature is 80-85°C, the time is 50-60 minutes, and the copper precipitation reaction is more thorough. Under the premise of ensuring complete copper precipitation, the arsenic content of the obtained copper sulfide slag is relatively high, which is affected by the reaction time and is 4.5% to 20%, which is not conducive to the thorough separation of copper and arsenic.

[0041] The results show that by prolonging the reaction time, As2S5 in the arsenic sulfide slag can basically react, leaving only As2S3 in the copper sulfide slag. This part of As2S3 is difficult to react with As(V) in the solution as shown in equation (2), mainly because the generated sulfur encapsulates and hinders the arsenic leaching reaction, resulting in a high level of residual arsenic in the copper sulfide slag, and metals such as zinc and nickel remain in the arsenic-containing solution and are not separated and recovered.

[0042] In view of the above analysis, the present invention provides a method for recovering metals from a high-arsenic copper-zinc solution, which adopts the process of "neutralization precipitation + alkaline sulfidation" to achieve complete separation and recycling of arsenic, copper and zinc.

[0043] Specifically, the present invention provides a method for recovering metal from a high-arsenic copper-zinc solution, the process flow of which is as follows: Figure 1As shown, it includes:

[0044] S1, adding a first alkaline reagent to a high-arsenic copper-zinc solution, controlling the pH to 5.5-7, and performing a neutralization precipitation reaction to obtain a high-arsenic solution and a copper-zinc-containing precipitate residue;

[0045] The high-arsenic copper-zinc solution includes but is not limited to smoke acid leaching solution, copper electrolysis solution or arsenic-containing copper solid waste acid leaching solution. The high-arsenic copper-zinc solution contains elements such as copper, zinc, arsenate, and arsenite, and the first alkaline reagent includes sodium hydroxide or ammonia water.

[0046] The neutralization precipitation reaction is carried out at room temperature, and the pH value of the system is adjusted by the first alkaline reagent. In addition, the alkaline leaching solution of the subsequent step S2 can also be returned to the neutralization precipitation reaction of this step as an alkaline regulator to adjust the pH. The alkaline leaching solution with a pH of about 11 to 13 also contains relatively high arsenic. After neutralization precipitation, it is enriched in the high-arsenic solution for separation and treatment. Through the neutralization precipitation reaction, more than 99.5% of copper and zinc can be enriched in the precipitated residue in the form of arsenate, sulfide, and hydroxide. The high-arsenic solution contains less than 5 ppm copper and less than 1 ppm zinc.

[0047] The main reactions in the neutralization precipitation stage are: copper and zinc react with arsenate, arsenite, hydroxide in the solution and sulfur ions or arsenic sulfide released by the alkaline leaching solution, and are converted into insoluble arsenate, arsenite, hydroxide, basic sulfate and a small amount of sulfide phases. Since the neutralization precipitation controls the pH at 5.5-7, no soluble zincate is produced, and ultimately copper and zinc can be enriched in the neutralization precipitation residue by more than 99.5%.

[0048] The main reactions are as follows:

[0049]

[0050] Cu 2+ +2OH - =Cu(OH)2↓ (10)

[0051] Cu 2+ +S 2- =CuS↓ (11)

[0052]

[0053] Zn 2+ +2OH - =Zn(OH)2↓ (14)

[0054]

[0055] 2Na3AsS4+3H2SO4=As2S5+3Na2SO4+3H2S↑ (17)

[0056] S2. Add arsenic sulfide slag and a second alkaline reagent to the precipitated slag, control the pH to 11-13, and perform alkaline leaching and sulfidation reaction to obtain low-arsenic slag and alkaline leaching solution.

[0057] The precipitated slag is first slurried with water, and then the arsenic sulfide slag and the second alkaline reagent are added, wherein the solid-liquid ratio of the precipitated slag to water is 1kg:5-7L. The amount of arsenic sulfide slag is 1.01 to 1.2 times the theoretical amount. The reaction temperature of the alkaline leaching sulfidation reaction is 45 to 95°C, and the reaction time is 1 to 4 hours.

[0058] Among them, the theoretical amount of arsenic sulfide slag is the theoretical amount of sulfur required after all the copper in the precipitated slag is converted into sulfide precipitation, and the theoretical amount divided by the percentage of sulfur in the arsenic sulfide slag is the amount of arsenic sulfide. The amount of arsenic sulfide added is higher than the theoretical amount to ensure that the arsenic-containing copper solution can convert all copper into sulfide precipitation, but too much arsenic sulfide dissolves in the alkaline solution and enters the solution in the form of thioarsenate. On the one hand, a large amount of alkali is consumed, which is easy to cause the accumulation of sulfur ions and return to the neutralization stage, and there is a risk that the pH is difficult to control; on the other hand, too much zinc will be converted into zinc sulfide, which is not conducive to the separation of copper and zinc in the subsequent acid leaching process. Through the above theoretical analysis, the preferred amount of arsenic sulfide slag in the present invention is 1.01 to 1.2 times the theoretical amount. It can be seen that the amount of arsenic sulfide slag in the present invention is significantly lower than the amount of arsenic sulfide slag (more than 1.3 times) in the current acidic environment, that is, a better effect can be achieved.

[0059] The alkaline leaching solution is returned to the neutralization precipitation reaction as an alkali regulator to adjust the pH. The alkaline leaching solution with a pH of about 11 to 13 also contains a high level of arsenic. After neutralization and precipitation, it is enriched in the high-arsenic solution for separation and treatment. Since the copper sulfide slag rate is low and the pH is controlled at 11 to 13, returning to the arsenic-containing copper solution as a regulator for neutralization and precipitation will not cause the pH in the solution to exceed the range of 7, so there is no need to consider the additional treatment of this part of the alkaline leaching solution.

[0060] The second alkaline agent includes sodium hydroxide.

[0061] The present invention adopts an alkaline system for arsenic removal, which can make the arsenic content of copper sulfide slag less than 0.5%. By controlling a certain amount of arsenic sulfide, pH and reaction time, copper is completely converted into sulfide and zinc is converted into zinc hydroxide, and the generation of zinc sulfide which is difficult to be removed by acid leaching is reduced as much as possible, thereby achieving complete separation of arsenic from copper and zinc.

[0062] The main reactions are as follows:

[0063] As2S3+Cu3(AsO4)2+4H2O=3CuS↓+2HAsO2+2H3AsO4 (18)

[0064] As2S3+Cu3(AsO3)2+6H2O=3CuS↓+4H3AsO3 (19)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0065] <h2 style=";text-align:left;direction:ltr"> 3As2S5+5Cu3(AsO4)2+24H2O=15CuS↓+16H3AsO4 (20)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0066] <h2 style=";text-align:left;direction:ltr"> 3As2S5+5Cu3(AsO3)2+24H2O=15CuS↓+10H3AsO3+6H3AsO4 (21)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0067] <h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0068] <h2 style=";text-align:left;direction:ltr"> As2S3+3Cu(OH)2=3CuS↓+2H3AsO3 (24)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0069] <h2 style=";text-align:left;direction:ltr"> As2S5+5Cu(OH)2=5CuS↓+2H3AsO4+2H2O (25)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0070] <h2 style=";text-align:left;direction:ltr"> As2S3+Zn3(AsO4)2+4H2O=3ZnS↓+2HAsO2+2H3AsO4 (26)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0071] <h2 style=";text-align:left;direction:ltr"> As2S3+Zn3(AsO3)2+6H2O=3ZnS↓+4H3AsO3 (27)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0072] <h2 style=";text-align:left;direction:ltr"> 3As2S5+5Zn3(AsO4)2+24H2O=15ZnS↓+16H3AsO4 (28)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0073] <h2 style=";text-align:left;direction:ltr"> 3As2S5+5Zn3(AsO3)2+24H2O=15ZnS↓+10H3AsO3+6H3AsO4 (29)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0074] <h2 style=";text-align:left;direction:ltr"> 3As2S5+5Zn3(AsO3)2+24H2O=15ZnS↓+10H3AsO3+6H3AsO4 (30)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0075] <h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0076] <h2 style=";text-align:left;direction:ltr"> As2S3+3Zn(OH)2=3ZnS↓+2H3AsO3 (33)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0077] <h2 style=";text-align:left;direction:ltr"> As2S5+5Zn(OH)2=5ZnS↓+2H3AsO4+2H2O (34)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0078] <h2 style=";text-align:left;direction:ltr"> As2S5+3H3AsO4=5HAsO2+5S+2H2O (35)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0079] <h2 style=";text-align:left;direction:ltr"> As2S3+3H3AsO4=5HAsO2+3S+2H2O (36)<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0080] <h2 style=";text-align:left;direction:ltr">

[0081] As2S5+6NaOH=Na3AsS4+Na3AsO3S+3H2O (38)

[0082]

[0083] Na3AsS3+2NaOH=Na3AsS2O+Na2S+H2O (41)

[0084] Na3AsS4+4NaOH(sufficient amount)=Na3AsO2S2+2Na2S+2H2O (42)

[0085] 2Na3AsS4+3H2SO4=As2S5+3Na2SO4+3H2S↑ (43)

[0086] 3S+5NaOH=2Na2S+Na2SO3+3H2O (44)

[0087] Therefore, controlling the amount of arsenic sulfide to 1.01 to 1.2 times the theoretical amount can ensure that all copper is converted into the copper sulfide phase; controlling the pH to 11 to 13 and the reaction time can ensure that zinc compounds will not be converted into soluble zincates, reducing zinc losses; excess arsenic sulfide is soluble in alkaline, and low-arsenic copper-zinc slag can be obtained. Ultimately, a more thorough separation of arsenic from copper and zinc is achieved, and low-arsenic slag with high copper and zinc recovery rates is obtained.

[0088] S3. The low-arsenic slag is leached with acid to obtain copper sulfide and zinc-containing solution.

[0089] In the present invention, the low-arsenic slag is acid-leached, wherein the pH of the acid-leaching is 1-4 and the acid used for the acid-leaching is sulfuric acid. The zinc-containing solution is returned to the acid-leaching step and circulated until the zinc content in the zinc-containing solution is ≥150g / L and the arsenic content is less than 0.2g / L, thereby obtaining a zinc solution to be electrolytically deposited, and electrolytically depositing the zinc solution to obtain a product of electrolytic zinc.

[0090] The main purpose of controlling the pH of acid leaching to 1-4 is to ensure that the zinc in the low-arsenic slag can be leached. The purpose is to ensure the subsequent electrolytic zinc deposition. The acidity should not be too high, as long as the zinc hydroxide can be dissolved. Of course, excessive acid can also achieve zinc leaching, but it will increase acid consumption and affect the acidity requirements for subsequent electrolytic zinc deposition.

[0091] The main reactions are as follows:

[0092] Zn(OH)2+H2SO4=ZnSO4+2H2O (45)

[0093] S4, adding an iron reagent to the high-arsenic solution, controlling the pH to 5-7, and performing an iron salt arsenic precipitation reaction to obtain a salt solution and arsenic iron slag, evaporating and crystallizing the salt solution to obtain a product industrial salt, and the arsenic iron slag is subjected to harmless treatment;

[0094] The high arsenic solution contains less than 5 ppm copper and less than 1 ppm zinc; the iron reagent includes ferric sulfate; the molar ratio of arsenic to iron in the high arsenic solution and the iron reagent is 1:4-6. The salt solution contains less than 1 ppm arsenic.

[0095] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0096] Example 1

[0097] This embodiment provides a method for recovering metal from a high-arsenic copper-zinc solution, which comprises the following steps:

[0098] S1. Composition of high-arsenic copper-zinc solution: As = 20.75 g / L, Cu = 13.42 g / L, Zn = 1.34 g / L, pH = 0.26. Sodium hydroxide was added to the high-arsenic copper-zinc solution, the pH was controlled to 6, and a neutralization precipitation reaction was performed. The reaction lasted for 30 minutes, and the high-arsenic solution and the copper-zinc-containing precipitate were obtained by filtration.

[0099] S2. Add water to the precipitated slag at a solid-liquid ratio of 1kg:6L to make a slurry, add 1.2 times the amount of arsenic sulfide slag, adjust the pH to 12 with sodium hydroxide, and carry out alkaline leaching and sulfidation reaction at 60°C for 1.5h. Filter to obtain low-arsenic slag and alkaline leaching solution, and return the alkaline leaching solution to the neutralization precipitation reaction as an alkali regulator to adjust the pH.

[0100] S3, the low-arsenic slag is leached with sulfuric acid, the pH is controlled at 2, and the reaction is carried out for 2 hours to obtain copper sulfide and a zinc-containing solution, and the zinc-containing solution is returned to the next acid leaching step.

[0101] S4. Add ferric sulfate to the high-arsenic solution at a molar ratio of arsenic to iron = 1:5, control the pH to 7, react for 30 minutes, and filter to obtain arsenic-iron slag and salt solution.

[0102] Example 2

[0103] This embodiment provides a method for recovering metal from a high-arsenic copper-zinc solution, which comprises the following steps:

[0104] S1. Composition of high-arsenic copper-zinc solution: As = 20.75 g / L, Cu 13.42 g / L, Zn 1.34 g / L, pH = 0.26. Sodium hydroxide was added to the high-arsenic copper-zinc solution, the pH was controlled to 5.5, and a neutralization precipitation reaction was carried out. The reaction lasted for 30 minutes, and the high-arsenic solution and the copper-zinc-containing precipitate were obtained by filtration.

[0105] S2. Add water to the precipitated slag at a solid-liquid ratio of 1kg:6L to make a slurry, add 1.1 times the amount of arsenic sulfide slag, adjust the pH to 11 with sodium hydroxide, carry out alkaline leaching and sulfidation reaction at 45°C for 4h, filter to obtain low-arsenic slag and alkaline leaching solution, and return the alkaline leaching solution to the neutralization precipitation reaction as an alkali regulator to adjust the pH.

[0106] S3, the low-arsenic slag is leached with sulfuric acid, the pH is controlled at 1, and the reaction is carried out for 2 hours to obtain copper sulfide and a zinc-containing solution, and the zinc-containing solution is returned to the next acid leaching step.

[0107] S4. Add ferric sulfate to the high-arsenic solution at a molar ratio of arsenic to iron = 1:4, control the pH to 5, react for 30 minutes, and filter to obtain arsenic-iron slag and salt solution.

[0108] Example 3

[0109] This embodiment provides a method for recovering metal from a high-arsenic copper-zinc solution, which comprises the following steps:

[0110] S1. Composition of high-arsenic copper-zinc solution: As = 20.75 g / L, Cu 13.42 g / L, Zn 1.34 g / L, pH = 0.26. Sodium hydroxide was added to the high-arsenic copper-zinc solution, the pH was controlled to 7, and a neutralization precipitation reaction was performed. The reaction lasted for 30 minutes, and the high-arsenic solution and the copper-zinc-containing precipitate were obtained by filtration.

[0111] S2. Add water to the precipitated slag at a solid-liquid ratio of 1kg:6L to make a slurry, add 1.01 times the amount of arsenic sulfide slag, adjust the pH to 13 with sodium hydroxide, and carry out alkaline leaching and sulfidation reaction at 95°C for 1h. Filter to obtain low-arsenic slag and alkaline leaching solution, and return the alkaline leaching solution to the neutralization precipitation reaction as an alkali regulator to adjust the pH.

[0112] S3. The low-arsenic slag is leached with sulfuric acid, the pH is controlled at 4, and the reaction is carried out for 2 hours to obtain copper sulfide and a zinc-containing solution, and the zinc-containing solution is returned to the next acid leaching solution.

[0113] S4. Add ferric sulfate to the high-arsenic solution at a molar ratio of arsenic to iron = 1:6, control the pH to 6, react for 30 minutes, and filter to obtain arsenic-iron slag and salt solution.

[0114] Comparative Example 1

[0115] This comparative example is basically the same as Example 1, except that the neutralization precipitation reaction in step S1 and the sodium hydroxide in step S2 are omitted in this comparative example. Specifically, it includes:

[0116] S1. Composition of high-arsenic copper-zinc solution: As = 20.75 g / L, Cu 13.42 g / L, Zn 1.34 g / L, pH = 0.26.

[0117] S2. Add 1.2 times the amount of arsenic sulfide slag to the high-arsenic copper-zinc solution, carry out sulfidation reaction at 60°C for 1.5 hours, and filter to obtain low-arsenic slag and zinc-arsenic solution.

[0118] S3, the low-arsenic slag is leached with sulfuric acid, the pH is controlled at 2, and the reaction is carried out for 2 hours to obtain copper sulfide and acid leaching solution, and the acid leaching solution is returned to the next acid leaching step.

[0119] S4. Add ferric sulfate to the zinc-arsenic solution at a molar ratio of arsenic to iron of 1:5, control the pH to 7, react for 30 minutes, and filter to obtain arsenic-iron slag and salt solution.

[0120] Comparative Example 2

[0121] This comparative example is basically the same as Example 1, except that the neutralization precipitation reaction in step S1 is omitted in this comparative example. Specifically, it includes:

[0122] S1. Composition of high-arsenic copper-zinc solution: As = 20.75 g / L, Cu 13.42 g / L, Zn 1.34 g / L, pH = 0.26.

[0123] S2. Add 1.2 times the amount of arsenic sulfide slag to the high-arsenic copper-zinc solution, adjust the pH to 12 with sodium hydroxide, carry out alkaline leaching and sulfidation reaction at 60°C for 1.5 hours, and filter to obtain low-arsenic slag and alkaline leaching solution.

[0124] S3. The low-arsenic slag is leached with sulfuric acid, the pH is controlled at 2, and the reaction is carried out for 2 hours to obtain copper sulfide and a zinc-containing solution, and the zinc-containing solution is returned to the next acid leaching solution.

[0125] S4, ferric sulfate is added to the alkaline leaching solution at a molar ratio of arsenic to iron = 1:5. At this time, it is found that the pH of the system is greater than 7 after the addition of ferric sulfate. Acid needs to be added to control the pH to 7. The reaction is carried out for 30 minutes, and arsenic iron slag and salt solution are obtained by filtration. Since the alkaline leaching solution contains more thioarsenate, it can provide more S 2- Iron sulfide is generated in the alkaline system and may be converted into ferrous sulfide and sulfur after adding acid, which is not conducive to the harmless treatment of arsenic iron slag.

[0126] Comparative Example 3

[0127] This comparative example is basically the same as Example 1, except that in this comparative example, only arsenic sulfide slag is added in step S2, and no sodium hydroxide is added. Specifically, it includes:

[0128] S1. Composition of high-arsenic copper-zinc solution: As = 20.75 g / L, Cu 13.42 g / L, Zn 1.34 g / L, pH = 0.26. Sodium hydroxide was added to the high-arsenic copper-zinc solution, the pH was controlled to 6, and a neutralization precipitation reaction was performed. The reaction lasted for 30 minutes, and the high-arsenic solution and the copper-zinc-containing precipitate were obtained by filtration.

[0129] S2. Add water to the precipitated residue at a solid-liquid ratio of 1kg:6L to make a slurry, add 1.2 times the amount of arsenic sulfide residue, react at 60°C for 1.5h, and filter to obtain low-arsenic residue and arsenic-containing filtrate.

[0130] S3. The low-arsenic slag is leached with sulfuric acid, the pH is controlled at 2, and the reaction is carried out for 2 hours to obtain copper sulfide and a high-arsenic zinc-containing solution (arsenic is greater than 0.2 g / L). The high-arsenic zinc-containing solution needs to be further separated from arsenic and zinc.

[0131] S4, high arsenic solution and arsenic-containing filtrate are added with ferric sulfate at a molar ratio of arsenic to iron = 1:5, the pH is controlled at 7, the reaction is carried out for 30 minutes, and arsenic-iron slag and salt solution are obtained by filtering.

[0132] Experimental example

[0133] The above-mentioned Examples 1-3 and Comparative Examples 1-3 were tested, and the test results were statistically shown as follows:

[0134]

[0135] As can be seen from the above table, the As content in the high-arsenic solution of Examples 1-3 of the present invention is relatively high, proving that most of the As in the high-arsenic copper-zinc solution enters the high-arsenic solution, and the content of impurities Cu and Zn in the high-arsenic solution is relatively low. In addition, the As content in the low-arsenic slag is also significantly lower than that in Comparative Examples 1-2, the As content in the dry basis copper sulfide is low and the Cu content is high, and the recovery rates of As, Cu and Zn are significantly higher than those in Comparative Examples 1-3.

[0136] In Comparative Example 1, since the neutralization precipitation step in step S1 and the sodium hydroxide in step S2 are omitted, the high-arsenic copper-zinc solution is directly subjected to sulfidation reaction with arsenic sulfide slag. At this time, the zinc-arsenic solution in Comparative Example 1, as a high-arsenic solution, has an As content significantly lower than that in Example 1, and the contents of impurities Cu and Zn are significantly higher than those in Example 1, while the As content in the low-arsenic slag is significantly increased, the As content in the dry basis copper sulfide is also significantly increased, and the recovery rates of As, Cu and Zn are significantly reduced.

[0137] In Comparative Example 2, only the neutralization precipitation step of step S1 is omitted. At this time, the alkaline leaching solution in Comparative Example 2 is used as a high-arsenic solution, and the arsenic concentration and impurity content are equivalent to those in the embodiment. The As content in the low-arsenic slag is significantly reduced compared with that in Comparative Example 1, but it is still higher than that in other embodiments. At the same time, the content of Cu and Zn is also reduced compared with that in the embodiment, and the As content in the dry copper sulfide is also slightly increased, greater than 0.5%. The recovery rates of As, Cu and Zn are equivalent to those in the embodiment. Since the alkaline leaching solution in Comparative Example 2 has more thioarsenate and hydroxide, more S can be converted into in the iron salt precipitation step. 2- A small amount of iron sulfide is easily generated, and with the addition of iron salts, the pH of the system decreases, which may be converted into ferrous sulfide and sulfur, which is not conducive to the harmless treatment of arsenic iron slag.

[0138] In comparative example 3, only arsenic sulfide slag is added in step S2, and sodium hydroxide is not added. At this time, the system is acidic. When the amount of arsenic sulfide is kept consistent with that in Example 1, its dissolution effect on As is significantly lower than that in Example 1, resulting in a large amount of As in the low-arsenic slag, which in turn leads to a significant increase in the As content in the dry basis copper sulfide, and a significant reduction in the recovery rate of As. At the same time, the high-arsenic zinc-containing solution obtained after acid leaching of the low-arsenic slag has a high arsenic content (arsenic is greater than 0.2 g / L), and cannot be directly electrolytically recovered zinc, which is not conducive to the recovery of zinc. It is necessary to further separate zinc and arsenic. After further separation, the recovery rate of zinc can reach 100%, but compared with Example 1, it adds a recovery step and reduces the production efficiency.

[0139] In summary, the method for recovering metal from a high-arsenic copper-zinc solution provided by the present invention adopts a process combining neutralization precipitation and alkaline sulfidation, which can separate arsenic and copper-zinc during the neutralization precipitation process, and then use alkaline sulfidation to react the copper-zinc-containing precipitate slag with arsenic sulfide slag in an alkaline system, wherein the copper and zinc can be sulfided into precipitation, and arsenic is released into the alkaline leaching solution, and the excess arsenic sulfide slag will be completely self-disproportionated in the subsequent alkaline leaching solution, and the alkaline leaching solution will return to the copper removal leaching section without causing the accumulation of arsenic sulfide. The unreacted arsenic sulfide slag will also dissolve with the alkali to finally obtain low-arsenic slag, which contains less than 0.5% arsenic (even less than 0.35%), and zinc in the system will not enter the solution, and the final metal recovery rate can reach more than 99.5%. Subsequently, acid leaching + electrolysis can be used to achieve a thorough separation of copper and zinc to obtain product electro zinc and copper sulfide. Arsenic precipitation by iron salt realizes the harmless treatment of arsenic, and the product industrial salt is obtained after evaporation and crystallization of the salt solution.

[0140] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for recovering metal from a high-arsenic copper-zinc solution, characterized in that: It includes: Adding a first alkaline reagent to a high-arsenic copper-zinc solution, controlling the pH value to be 5.5-7, and performing a neutralization precipitation reaction to obtain a high-arsenic solution and a copper-zinc-containing precipitated residue; Adding arsenic sulfide slag and a second alkaline reagent to the precipitated slag, controlling the pH to 11-13, and performing an alkaline leaching and sulfidation reaction to obtain an alkaline leaching solution and a low-arsenic slag with an arsenic content of ≤0.5%; The low-arsenic slag is subjected to acid leaching to obtain copper sulfide and a zinc-containing solution.

2. The method for recovering metal from a high-arsenic copper-zinc solution according to claim 1, characterized in that: The reaction temperature of the alkaline leaching vulcanization reaction is 45 to 95°C, and the reaction time is 1 to 4 hours; Preferably, the amount of the arsenic sulfide slag is 1.01 to 1.2 times the theoretical amount.

3. The method for recovering metal from a high-arsenic copper-zinc solution according to claim 1, characterized in that: The precipitated slag is firstly slurried by adding water, and then the arsenic sulfide slag and the second alkaline reagent are added, wherein the solid-liquid ratio of the precipitated slag to the water is 1kg:5-7L.

4. The method for recovering metal from a high-arsenic copper-zinc solution according to claim 1, characterized in that: The alkaline leaching solution is returned to the neutralization precipitation reaction as an alkaline regulator to adjust the pH.

5. The method for recovering metal from a high-arsenic copper-zinc solution according to claim 1, characterized in that: The first alkaline reagent includes sodium hydroxide or ammonia water, and the second alkaline reagent includes sodium hydroxide.

6. The method for recovering metal from a high-arsenic copper-zinc solution according to any one of claims 1 to 5, characterized in that: The pH of the acid leaching is 1 to 4; Preferably, the acid used for pickling is sulfuric acid.

7. The method for recovering metal from a high-arsenic copper-zinc solution according to any one of claims 1 to 5, characterized in that: The zinc-containing solution is returned to the acid leaching step and circulated until the zinc content in the zinc-containing solution is ≥150 g / L and the arsenic content is less than 0.2 g / L, thereby obtaining a zinc solution to be electrolytically deposited. The zinc solution to be electrolytically deposited is electrolytically deposited to obtain product electrolytic zinc.

8. The method for recovering metal from a high-arsenic copper-zinc solution according to any one of claims 1 to 5, characterized in that: Adding an iron reagent to the high-arsenic solution, controlling the pH to be 5-7, and performing an iron salt arsenic precipitation reaction to obtain a salt solution and arsenic iron slag; Preferably, the high-arsenic solution contains less than 5 ppm copper and less than 1 ppm zinc; Preferably, the iron reagent comprises ferric sulfate; Preferably, the molar ratio of arsenic to iron in the high-arsenic solution and the iron reagent is 1:4-6.

9. The method for recovering metal from a high-arsenic copper-zinc solution according to claim 8, characterized in that: The salt solution is evaporated and crystallized to obtain industrial salt product, and the arsenic iron slag is treated to be harmless; Preferably, the salt solution contains less than 1 ppm of arsenic.

10. The method for recovering metal from a high-arsenic copper-zinc solution according to any one of claims 1 to 5, characterized in that: The high-arsenic copper-zinc solution includes smoke acid leaching solution, copper electrolysis solution or arsenic-containing copper solid waste acid leaching solution.

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