A method for recovering valuable elements from polymetallic arsenic acid wastewater

Abstract

The present invention relates to a method for recovering valuable elements from polymetallic arsenic acidic wastewater, comprising the following steps: metal element content detection; mixed precipitation of copper, arsenic, gold, and silver; purification of the acidic mother liquor for iron removal; preparation of high-quality gypsum; two-stage leaching of the harmful element arsenic; and arsenic solidification treatment. The method utilizes a rational combination of sodium hydrosulfide and 25# black powder to fully precipitate copper arsenic ions and fine gold and silver particles in the acidic wastewater, significantly improving the recovery rate of the target components. The precipitate is then subjected to two-stage leaching for arsenic removal using either a raw acidic wastewater solution or the addition of copper sulfate, thereby obtaining high-quality gold, silver, and copper concentrate while reducing the amount of copper sulfate used. The filtered iron-containing acidic mother liquor is then subjected to iron removal and gypsum treatment to produce high-quality gypsum and ferric hydroxide. The intermediate product, ferric hydroxide, is then directly used for arsenic removal from the arsenic-containing acidic mother liquor. Through a synergistic effect with lime milk, the harmful element arsenic can be efficiently removed, achieving comprehensive recovery and harmless treatment of the valuable elements in the acidic wastewater.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a method for recovering valuable elements in polymetallic arsenic acid wastewater. Background Art

[0002] Non-ferrous metal smelting enterprises generate large quantities of acidic wastewater containing polymetallic arsenic during their production processes. This acidic wastewater is complex in nature, and its composition often varies significantly depending on the production process. Typically, the arsenic in this acidic wastewater is treated through wet precipitation to form gypsum slag or sulfide precipitation to produce an arsenic filter cake, but the valuable metals in this wastewater are not recovered. With the development and utilization of mineral resources and the continued rise in international gold prices, the recovery of valuable metals such as gold, silver, and copper from wastewater is gaining increasing attention. This is particularly true of wastewater generated by washing or acid leaching the roasting slag of polymetallic sulfide ores containing gold and silver, which has a high recovery value for valuable elements. In this wastewater, gold and silver exist as fine particles, while copper, arsenic, and iron exist as ions. Due to these different forms of existence, the comprehensive and effective recovery of valuable metals is difficult.

[0003] The main sedimentation recovery methods for this type of wastewater are lime-iron salt method, sulfide method, etc. The valuable metals and harmful elements in the precipitate are recovered and reduced in harm through methods such as hydrometallurgy, pyrometallurgy and flotation. These methods have more or less deficiencies and defects in application. Either the valuable components cannot be effectively recovered, or secondary pollution is generated again, which has a serious impact on the natural environment. (1) Lime method: The calcium hydroxide product after lime hydrolysis reacts with arsenate to form calcium arsenate precipitate. In order to improve the effect of arsenic removal, the pH value is generally controlled at 9-10.5. Under such conditions, other valuable metals are easy to form co-precipitation, producing a large amount of sediment, the recovery rate of valuable metals is low, and the subsequent processing cost is high; (2) Iron salt method: Iron ions are used to produce a large amount of iron hydroxide colloidal particles under pH conditions of 3-5.4, thereby adsorbing and co-precipitating arsenate ions. In this method, the valuable components will also be co-precipitated and cannot be effectively recovered; (3) Sulfide flotation method: Using After the sulfiding agent precipitates the valuable metal ions, the flotation method is used to recover them, and the flotation tailings or tailings are then treated. This method will cause the arsenic in the waste liquid to be sulfided and floated into the product, resulting in unqualified products. The flotation foaming effect of fine particles is poor, and the recovery rate is low. In addition, the process is long and the investment is large, which affects the economic benefits of the enterprise. (4) Fire smelting: Fire smelting removes arsenic and recovers valuable metals. The process is complex, costly, and causes serious secondary environmental pollution. (5) Cyanide leaching: Cyanide is used to react with gold and silver to form a soluble complex, allowing gold and silver to enter the solution, thereby achieving the extraction of gold and silver. This method requires the use of highly toxic cyanide. Not only is the cost of the agent high, the leaching rate of gold and silver is low, and copper is difficult to recover, but the cyanide slag produced also faces the environmental problem of secondary pollution.

[0004] In order to overcome the deficiencies and defects of the prior art, the present invention provides a method for recovering valuable elements from polymetallic arsenic acid wastewater, so as to economically and environmentally recover valuable metals from arsenic acid wastewater. Summary of the Invention

[0005] The present invention provides a method for recovering valuable elements from polymetallic arsenic wastewater. This method targets gold-containing polymetallic arsenic wastewater by adding sodium hydrosulfide to precipitate copper and arsenic ions. After the reaction is complete, a small amount of 25# black powder is added to enhance the hydrophobicity of fine gold and silver particles, allowing them to co-precipitate with copper and arsenic. The filtered and separated acidic mother liquor is then de-ironized (forming ferric hydroxide) to produce high-purity gypsum. The precipitate undergoes two-stage leaching to remove arsenic, yielding a gold, silver, and copper concentrate and an arsenic-containing mother liquor. Ferric hydroxide and lime are then added sequentially to the arsenic-containing mother liquor for arsenic removal and purification, achieving both harmless treatment of the acidic wastewater and comprehensive recovery of valuable elements. The technical solution includes:

[0006] (1) Detection of metal element content: Take a certain amount of polymetallic arsenic acid wastewater to be treated and determine the contents of copper, arsenic, gold, silver and iron respectively;

[0007] (2) Mixed precipitation of copper, arsenic, gold and silver: add 20% sodium hydrosulfide solution to acidic wastewater for stirring and precipitation to precipitate copper and arsenic ions. After stirring for 15 minutes, add 25# black medicine and stir for 2 to 4 minutes to enhance the hydrophobicity of fine particles of gold and silver, so that fine particles of gold and silver are co-precipitated with copper and arsenic. Then, thicken and filter to obtain a mixed precipitate containing copper, arsenic, gold and silver and an acidic mother liquor.

[0008] (3) Purification of the acidic mother liquor for iron removal: After introducing air into the acidic mother liquor obtained in step (2) and stirring for 5 to 10 minutes, a 10% sodium hydroxide solution is added, the pH value is controlled at 3 to 4, the stirring reaction time is 10 to 20 minutes, and then the solution is concentrated and filtered to obtain iron hydroxide and iron removal mother liquor;

[0009] (4) Preparation of high-quality gypsum: Add 10% lime milk to the iron removal mother liquor obtained in step (3), control the pH value at 7-7.5, stir and react for 15 minutes, then thicken and filter to obtain high-quality gypsum and dischargeable purified water;

[0010] (5) Two-stage leaching of harmful element arsenic:

[0011] Primary leaching and arsenic removal: adding a certain amount of polymetallic arsenic acid wastewater or copper sulfate to the mixed precipitate containing copper, arsenic, gold and silver obtained in step (2) to carry out primary leaching and arsenic removal, leaching for 1.5 to 2 hours, and then thickening and filtering to obtain a gold and silver precipitate and an arsenic acid mother liquor I;

[0012] Secondary leaching and arsenic removal: A certain amount of polymetallic arsenic acid wastewater or copper sulfate is added to the gold-silver precipitate obtained by the primary leaching and arsenic removal to perform secondary leaching and arsenic removal. The leaching time is 0.5 to 1 hour, followed by thickening and filtration separation to obtain high-quality gold, silver and copper concentrate and arsenic acid mother liquor II.

[0013] (6) Arsenic solidification treatment: After combining the arsenic-containing acid mother liquors I and II obtained in step (5), add the ferric hydroxide obtained in step (3), stir and react for 10 to 15 minutes, then add 10% lime milk, control the pH value at 7 to 7.5, stir and react for 10 to 15 minutes, then thicken and filter to obtain arsenic-containing slag and purified water that can be discharged.

[0014] Furthermore, in step (2), sodium hydrosulfide is reacted according to the chemical reaction equation Cu 2+ +S 2- =CuS and 2H3AsO3+3S 2- +6H + =As2S3↓+6H2O Add 1.2 to 1.4 times the theoretical cumulative amount.

[0015] Furthermore, the amount of 25# black medicine added in step (2) is 10g / m 3 .

[0016] Furthermore, in step (5), the amount of copper sulfate added to the wastewater containing polymetallic arsenic or the copper sulfate added during the primary leaching and arsenic removal is calculated according to the chemical reaction equation 3Cu 2+ +3As2S3+6H2O=3CuS+3H3AsO4+3SO2 is added at 0.8 to 0.9 times the theoretically calculated amount of copper.

[0017] Furthermore, in step (5), the amount of copper sulfate added to the wastewater containing polymetallic arsenic or the copper sulfate added during the secondary leaching and arsenic removal is calculated according to the chemical reaction equation 3Cu 2+ +3As2S3+6H2O=3CuS+3H3AsO4+3SO2 is added at 0.2 to 0.3 times of the theoretically calculated amount of copper, and the copper concentration of the solution is controlled to be 2 to 3 times the copper concentration of the first-level leaching solution.

[0018] The beneficial effects of the present invention are as follows: the method of the present invention firstly fully precipitates copper arsenic ions and fine gold and silver particles in acidic wastewater by rationally combining sodium hydrosulfide and 25# black medicine, thereby greatly improving the recovery rate of target components; then, the precipitate is subjected to two-stage leaching and arsenic removal by means of the acidic wastewater stock solution or by simultaneously supplementing copper sulfate, thereby obtaining high-quality gold, silver and copper concentrate while reducing the amount of copper sulfate used; and the filtered iron-containing acidic mother liquor is subjected to iron removal and gypsum preparation to obtain high-quality gypsum and ferric hydroxide, and then the intermediate product ferric hydroxide is directly used for arsenic removal treatment of the arsenic-containing acidic mother liquor. Under the synergistic effect with lime milk, the harmful element arsenic can be efficiently removed, truly realizing the comprehensive recovery and harmless treatment of valuable elements in acidic wastewater, and the recovery quality and recovery rate of each valuable element are remarkable, fully realizing the maximization of resource value, and the treated wastewater also meets the industrial wastewater discharge standard, which is conducive to reducing the risk of environmental pollution and has good economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a flow chart of a method for recovering valuable elements from polymetallic arsenic acid wastewater according to the present invention. DETAILED DESCRIPTION

[0020] In order to make the technical problems and technical solutions solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Example 1

[0021] Raw material 1#: A polymetallic arsenic acid wastewater, with a solution pH of 1.8 and metal element content of: arsenic 512 mg / L, copper 1650 mg / L, gold 0.15 mg / L, silver 0.048 mg / L, and iron 4700 mg / L.

[0022] like Figure 1 As shown, the present invention is used to recover valuable elements from polymetallic arsenic acid wastewater, and the specific technical solution includes:

[0023] (1) Detection of metal element content: Take a certain amount of polymetallic arsenic acid wastewater to be treated and determine the contents of copper, arsenic, gold, silver and iron respectively;

[0024] (2) Mixed precipitation of copper, arsenic, gold and silver: add 20% sodium hydrosulfide solution to the acidic wastewater for stirring and precipitation to precipitate copper and arsenic ions. After stirring for 15 minutes, add 25# black medicine 10g / m 3, stirring time 2 to 4 minutes, strengthen the hydrophobicity of fine particles of gold and silver, make fine particles of gold and silver co-precipitate with copper and arsenic, and then thicken and filter to obtain a mixed precipitate containing copper, arsenic, gold and silver and an acidic mother liquor; in this process, sodium hydrosulfide reacts according to the chemical reaction equation Cu 2+ +S 2- =CuS and 2H3AsO3+3S 2- +6H + =As2S3↓+6H2O Add 1.2 to 1.4 times the theoretical cumulative amount.

[0025] (3) Purification of the acidic mother liquor for iron removal: After introducing air into the acidic mother liquor obtained in step (2) and stirring for 5 to 10 minutes, a 10% sodium hydroxide solution is added, the pH value is controlled at 3 to 4, the stirring reaction time is 10 to 20 minutes, and then the solution is concentrated and filtered to obtain iron hydroxide and iron removal mother liquor;

[0026] (4) Preparation of high-quality gypsum: Add 10% lime milk to the iron removal mother liquor obtained in step (3), control the pH value at 7-7.5, stir and react for 15 minutes, then thicken and filter to obtain high-quality gypsum and dischargeable purified water;

[0027] (5) Two-stage leaching of harmful element arsenic:

[0028] Primary leaching arsenic removal: Add a certain amount of polymetallic arsenic acid wastewater or copper sulfate to the mixed precipitate containing copper, arsenic, gold and silver obtained in step (2) to carry out primary leaching arsenic removal, wherein the amount of polymetallic arsenic acid wastewater or copper sulfate added is as follows: 2+ +3As2S3+6H2O=3CuS+3H3AsO4+3SO2 is added at 0.8 to 0.9 times of the theoretically calculated amount of copper, leached for 1.5 to 2 hours, then concentrated and filtered to obtain a precipitate containing gold and silver and a mother liquor containing arsenic acid I;

[0029] Secondary leaching and arsenic removal: A certain amount of acidic wastewater containing polymetallic arsenic or copper sulfate is added to the gold and silver precipitate obtained by primary leaching and arsenic removal for secondary leaching and arsenic removal. The amount of polymetallic wastewater or copper sulfate added is calculated according to the chemical reaction equation 3Cu 2+ +3As2S3+6H2O=3CuS+3H3AsO4+3SO2 is added at 0.2-0.3 times of the theoretically calculated copper amount, and the copper concentration of the solution is controlled to be 2-3 times of the copper concentration of the primary leaching solution. The leaching time is 0.5-1 hour, and then thickening and filtration separation are carried out to obtain high-quality gold, silver and copper concentrate and arsenic acid mother liquor II;

[0030] (6) Arsenic solidification treatment: After combining the arsenic-containing acid mother liquors I and II obtained in step (5), add the ferric hydroxide obtained in step (3), stir and react for 10 to 15 minutes, then add 10% lime milk, control the pH value at 7 to 7.5, stir and react for 10 to 15 minutes, then thicken and filter to obtain arsenic-containing slag and purified water that can be discharged.

[0031] The test results obtained were: copper concentrate with a gold grade of 27.64g / t, a silver grade of 9.75g / t, and a copper grade of 40.85%. The gold, silver, and copper recoveries were 77.99%, 78.25%, and 95.38%, respectively. Example 2

[0032] Raw material 2#: A polymetallic arsenic acid wastewater, with a solution pH of 2.2 and metal element content of: arsenic 486 mg / L, copper 1130 mg / L, gold 0.18 mg / L, silver 0.075 mg / L, and iron 5100 mg / L.

[0033] like Figure 1 As shown, the present invention is implemented on the complex platinum-palladium concentrate, and the specific steps are as follows:

[0034] like Figure 1 As shown, the present invention is used to recover valuable elements from polymetallic arsenic acid wastewater, and the specific technical solution includes:

[0035] (1) Detection of metal element content: Take a certain amount of polymetallic arsenic acid wastewater to be treated and determine the contents of copper, arsenic, gold, silver and iron respectively;

[0036] (2) Mixed precipitation of copper, arsenic, gold and silver: add 20% sodium hydrosulfide solution to the acidic wastewater for stirring and precipitation to precipitate copper and arsenic ions. After stirring for 15 minutes, add 25# black medicine 10g / m 3 , stirring time 2 to 4 minutes, strengthen the hydrophobicity of fine particles of gold and silver, make fine particles of gold and silver co-precipitate with copper and arsenic, and then thicken and filter to obtain a mixed precipitate containing copper, arsenic, gold and silver and an acidic mother liquor; in this process, sodium hydrosulfide reacts according to the chemical reaction equation Cu 2+ +S 2- =CuS and 2H3AsO3+3S 2- +6H + =As2S3↓+6H2O Add 1.2 to 1.4 times the theoretical cumulative amount.

[0037] (3) Purification of the acidic mother liquor for iron removal: After introducing air into the acidic mother liquor obtained in step (2) and stirring for 5 to 10 minutes, a 10% sodium hydroxide solution is added, the pH value is controlled at 3 to 4, the stirring reaction time is 10 to 20 minutes, and then the solution is concentrated and filtered to obtain iron hydroxide and iron removal mother liquor;

[0038] (4) Preparation of high-quality gypsum: Add 10% lime milk to the iron removal mother liquor obtained in step (3), control the pH value at 7-7.5, stir and react for 15 minutes, then thicken and filter to obtain high-quality gypsum and dischargeable purified water;

[0039] (5) Two-stage leaching of harmful element arsenic:

[0040] Primary leaching arsenic removal: Add a certain amount of polymetallic arsenic acid wastewater or copper sulfate to the mixed precipitate containing copper, arsenic, gold and silver obtained in step (2) to carry out primary leaching arsenic removal, wherein the amount of polymetallic arsenic acid wastewater or copper sulfate added is as follows: 2+ +3As2S3+6H2O=3CuS+3H3AsO4+3SO2 is added at 0.8~0.9 times of the theoretically calculated amount of copper, leached for 1.5~2 hours, then concentrated and filtered to obtain gold and silver precipitates and arsenic acid mother liquor I;

[0041] Secondary leaching and arsenic removal: A certain amount of acidic wastewater containing polymetallic arsenic or copper sulfate is added to the gold and silver precipitate obtained by primary leaching and arsenic removal for secondary leaching and arsenic removal. The amount of polymetallic wastewater or copper sulfate added is calculated according to the chemical reaction equation 3Cu 2+ +3As2S3+6H2O=3CuS+3H3AsO4+3SO2 is added at 0.2-0.3 times of the theoretically calculated copper amount, and the copper concentration of the solution is controlled to be 2-3 times of the copper concentration of the primary leaching solution. The leaching time is 0.5-1 hour, and then thickening and filtration separation are carried out to obtain high-quality gold, silver and copper concentrate and arsenic acid mother liquor II;

[0042] (6) Arsenic solidification treatment: After combining the arsenic-containing acid mother liquors I and II obtained in step (5), add the ferric hydroxide obtained in step (3), stir and react for 10 to 15 minutes, then add 10% lime milk, control the pH value at 7 to 7.5, stir and react for 10 to 15 minutes, then thicken and filter to obtain arsenic-containing slag and purified water that can be discharged.

[0043] The test results obtained were: copper concentrate with a gold grade of 26.89g / t, a silver grade of 10.25g / t, and a copper grade of 38.96%. The gold, silver, and copper recoveries were 78.30%, 77.19%, and 94.92%, respectively.

[0044] As can be seen from the above examples, the method of the present invention can be used to treat polymetallic acidic wastewater, thereby comprehensively recovering the valuable elements gold, silver, and copper therein, with a gold recovery rate of approximately 78%, a silver recovery rate of approximately 78%, and a copper recovery rate of approximately 95%, truly realizing comprehensive resource utilization. At the same time, the intermediate product, ferric hydroxide, can be used to remove arsenic from the wastewater, ensuring that the acidic wastewater meets discharge standards, truly achieving harmless treatment, reducing the risk of environmental pollution, and having good economic and environmental benefits.

[0045] The present invention is described in detail above through specific and preferred embodiments, but those skilled in the art should understand that the present invention is not limited to the embodiments described above. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for recovering valuable elements from polymetallic arsenic acid wastewater, characterized in that: The steps include: (1) Detection of metal element content: Take a certain amount of polymetallic arsenic acid wastewater to be treated and determine the contents of copper, arsenic, gold, silver and iron respectively; (2) Mixed precipitation of copper, arsenic, gold and silver: add 20% sodium hydrosulfide solution to acidic wastewater for stirring and precipitation. After stirring for 15 minutes, add 25# black medicine and stir for 2 to 4 minutes to make fine particles of gold and silver co-precipitate with copper and arsenic. Then, thicken and filter to obtain a mixed precipitate containing copper, arsenic, gold and silver and an acidic mother liquor. (3) Purification of the acidic mother liquor for iron removal: After introducing air into the acidic mother liquor obtained in step (2) and stirring for 5 to 10 minutes, a 10% sodium hydroxide solution is added, the pH value is controlled at 3 to 4, the stirring reaction time is 10 to 20 minutes, and then the solution is concentrated and filtered to obtain iron hydroxide and iron removal mother liquor; (4) Preparation of high-quality gypsum: Add 10% lime milk to the iron removal mother liquor obtained in step (3), control the pH value at 7-7.5, stir and react for 15 minutes, then thicken and filter to obtain high-quality gypsum and dischargeable purified water; (5) Two-stage leaching of harmful element arsenic: Primary leaching and arsenic removal: adding a certain amount of polymetallic arsenic acid wastewater or copper sulfate to the mixed precipitate containing copper, arsenic, gold and silver obtained in step (2) to carry out primary leaching and arsenic removal, leaching for 1.5 to 2 hours, and then thickening and filtering to obtain a gold and silver precipitate and an arsenic acid mother liquor I; Secondary leaching and arsenic removal: A certain amount of polymetallic arsenic acid wastewater or copper sulfate is added to the gold-silver precipitate obtained by the primary leaching and arsenic removal to perform secondary leaching and arsenic removal. The leaching time is 0.5 to 1 hour, followed by thickening and filtration separation to obtain high-quality gold, silver and copper concentrate and arsenic acid mother liquor II. (6) Arsenic solidification treatment: After combining the arsenic-containing acid mother liquors I and II obtained in step (5), add the ferric hydroxide obtained in step (3), stir and react for 10 to 15 minutes, then add 10% lime milk, control the pH value at 7 to 7.5, stir and react for 10 to 15 minutes, then thicken and filter to obtain arsenic-containing slag and purified water that can be discharged.

2. The method for recovering valuable elements from polymetallic arsenic acid wastewater according to claim 1, characterized in that: In step (2), sodium hydrosulfide is reacted according to the chemical reaction equation Add 1.2 to 1.4 times the theoretical cumulative amount.

3. The method for recovering valuable elements from polymetallic arsenic acid wastewater according to claim 1 or 2, characterized in that: The amount of 25# black medicine added in step (2) is 10g / m 3 .

4. The method for recovering valuable elements from polymetallic arsenic acid wastewater according to claim 1, characterized in that: In step (5), the amount of copper sulfate added to the wastewater containing polymetallic arsenic or the copper sulfate added at the same time during the primary leaching and arsenic removal is calculated according to the chemical reaction equation: Add 0.8 to 0.9 times the theoretically calculated amount of copper.

5. The method for recovering valuable elements from polymetallic arsenic acid wastewater according to claim 1 or 4, characterized in that: In step (5), the amount of copper sulfate added to the wastewater containing polymetallic arsenic or the copper sulfate added at the same time during the secondary leaching and arsenic removal is calculated according to the chemical reaction equation: 0.2 to 0.3 times of the theoretically calculated amount of copper is added, and the copper concentration of the solution is controlled to be 2 to 3 times the copper concentration of the primary leaching solution.

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