A method for recovering valuable elements from high-copper, high-arsenic, and high-nickel wastewater by controlled potential stepwise recovery

Abstract

The invention belongs to the technical field of industrial wastewater treatment and specifically discloses a method for recovering valuable elements in high-copper, high-arsenic, and high-nickel wastewater by controlling potential stepwise. The method comprises the following steps: filtering the high-copper, high-arsenic, and high-nickel wastewater, performing a first-stage sulfidation reaction using sodium thiosulfate to obtain a first-stage sulfided slag containing copper and a first-stage post-sulfided liquid; adding a sulfiding agent to the first-stage post-sulfided liquid to carry out a second-stage sulfidation reaction to obtain a second-stage sulfided slag containing arsenic and a second-stage post-sulfided liquid; adding an alkaline substance to the second-stage post-sulfided liquid to obtain a neutralized slag and a neutralized liquid; and finally, leaching treatment, step-by-step hydrolysis, and low-temperature cooking are performed on the first-stage sulfided slag and the second-stage sulfided slag respectively to obtain copper and arsenic substances. The method has the advantages of simple operation, complete separation of copper, arsenic, and nickel, high recovery rate, short process, good selective separation effect, and the like. The neutralized slag can be exported as an industrial product, thereby realizing resource recovery of valuable elements in the high-copper, high-arsenic, and high-nickel wastewater.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial wastewater treatment, and particularly relates to a method for controlling potential in a stepwise manner to recover valuable elements from high-copper, high-arsenic, and high-nickel wastewater. Background Art

[0002] In order to avoid the waste of valuable elements (mainly nickel, copper, arsenic, etc.) when treating high-copper, high-arsenic, and high-nickel wastewater, it is necessary to recover copper, nickel, and arsenic from the wastewater. The current traditional nickel recovery process first performs a diffusion dialysis deacidification and dearsenicization on the copper sulfate mother liquor, then neutralizes the diffusion residual liquid to remove copper and arsenic, and then deeply neutralizes and extracts high-copper, high-arsenic, and high-nickel slag as the raw material for extracting nickel. Since the nickel-containing material contains impurities such as copper and arsenic, the main grade of nickel is low, resulting in a long nickel product extraction process, high alkali consumption, complex procedures, and greatly reduced nickel direct recovery and recovery rates. Therefore, we need to propose a method for controlling potential step-by-step recovery of valuable elements in high-copper, high-arsenic, and high-nickel wastewater to solve the above-mentioned problems, so that it can effectively improve the recovery rate of valuable elements. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for controlling potential and stepwise recovery of valuable elements in high-copper, high-arsenic, and high-nickel wastewater, which can effectively improve the resource recovery of valuable elements in high-copper, high-arsenic, and high-nickel wastewater to solve the problems raised in the above background technology.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for recovering valuable elements from high-copper, high-arsenic, and high-nickel wastewater by controlled potential stepwise recovery comprises the following steps:

[0006] S1. Filter the high-copper, high-arsenic, and high-nickel wastewater using a filtering device to remove suspended solids and particulate matter in the high-copper, high-arsenic, and high-nickel wastewater;

[0007] S2. Adding sodium thiosulfate to the filtered high-copper, high-arsenic, and high-nickel wastewater to carry out a temperature- and potential-controlled sulfidation reaction, separating the sulfided slag and the post-sulfidation liquid to obtain a copper-containing section of sulfided slag and a section of post-sulfidation liquid;

[0008] S3, adding a sulfiding agent to the first-stage sulfided liquid to carry out a sulfidation reaction under temperature and potential control, and then separating the sulfided slag and the sulfided liquid to obtain arsenic-containing second-stage sulfided slag and second-stage sulfided liquid;

[0009] S4, adding alkaline substances to the liquid after the second stage sulfidation to carry out a neutralization reaction under temperature and potential control, and then separating the slag and the neutralization liquid to obtain nickel-containing neutralized slag;

[0010] S5. Leaching the first-stage sulfide slag and the second-stage sulfide slag with chloride salt to obtain a first-stage leachate and a second-stage leachate respectively;

[0011] S6. Hydrolyzing the first-stage leachate and the second-stage leachate in steps, and then respectively performing low-temperature blowing on the first-stage precipitate and the second-stage precipitate after the hydrolysis to obtain copper substances and arsenic substances.

[0012] Preferably, in step S1, when filtering the high-copper, high-arsenic, and high-nickel wastewater, the wastewater is introduced into a filtering device, and the suspended matter and particulate matter are intercepted by the filter medium in the filtering device, while the liquid is allowed to flow out through the filter medium, and the suspended matter and particulate matter accumulated on the filter medium are backwashed to flush the intercepted suspended matter and particulate matter from the filter medium. After the filtration is completed, the waste residue generated during the filtration process is collected and the waste residue is treated as solid waste.

[0013] Preferably, in step S2, the sodium thiosulfate is in a solid or liquid state, and the conditions for adding sodium thiosulfate for the sulfidation reaction are: reaction temperature 50-100°C, reaction time 0.5-5h, reaction endpoint potential 200-300mV, and stirring equipment is required to stir the reaction liquid at a stirring speed of 100-600r / min.

[0014] Preferably, in step S3, the sulfiding agent is set to one or more of sodium sulfide, sodium hydrosulfide and hydrogen sulfide, and the conditions of the sulfiding reaction after adding the sulfiding agent are: reaction temperature 10-40°C, reaction time 0.5-4h, reaction endpoint potential 50-180mV, stirring operation needs to be added during the reaction, and the stirring speed is 100-600r / min.

[0015] Preferably, in step S4, the alkaline substance is set to one or more of sodium hydroxide, calcium hydroxide and potassium hydroxide, and the neutralization solution needs to be stirred during the neutralization reaction. The conditions of the neutralization reaction are: reaction temperature 20-80°C, reaction time 0.5-3h, stirring speed 100-600r / min, and reaction endpoint potential -100-30mV.

[0016] Preferably, in step S5, the chloride salt is set to sodium chloride or calcium chloride, and the leaching treatment of the first stage sulfide slag includes the following steps:

[0017] A1. Mix a section of sulfide slag with chloride salt to form a slurry;

[0018] A2. Add the slurry to a leaching tank, maintain the temperature at 50-90°C and stir, and introduce air or chlorine gas for oxidation, so that copper and arsenic are dissolved into the solution in the form of chlorides;

[0019] A3. After leaching the solution for 10-20 hours, separate the solid residue and the leachate by filtration or sedimentation to obtain a leachate;

[0020] The leaching treatment method of the second-stage sulfide slag is the same as the leaching treatment method of the first-stage sulfide slag to obtain the second-stage leachate.

[0021] Preferably, in step S6, when the first stage leachate is subjected to step-by-step hydrolysis, the pH value of the first stage leachate is adjusted to 6-8 according to the chemical properties of copper, and then sodium hydroxide is added to carry out a hydrolysis reaction to form a copper-containing hydroxide precipitate, which is the first stage precipitate.

[0022] Preferably, when the first-stage precipitate is subjected to low-temperature blowing, the first-stage precipitate is fed into a blowing furnace, the temperature of the blowing furnace is controlled at 1200° C.-1400° C., coke or charcoal is used as a reducing agent, and the blowing furnace is placed in a reducing atmosphere, so that the copper compound is reduced and exists in the form of dust, and finally the dust is collected and subjected to copper purification treatment.

[0023] Preferably, during the step-by-step hydrolysis of the second-stage leachate, the pH value of the second-stage leachate is adjusted to 2-4 according to the chemical properties of arsenic to precipitate arsenic, and then sodium hydroxide is added to carry out a hydrolysis reaction to form a hydroxide precipitate containing arsenic. The hydroxide precipitate containing arsenic is the second-stage precipitate.

[0024] Preferably, when the second-stage precipitate is subjected to low-temperature blowing, the second-stage precipitate is fed into a blowing furnace at a temperature of 400-550°C, and coke or charcoal is used as a reducing agent to reduce the arsenic compound so that the arsenic exists in the blowing furnace in the form of steam. The steam in the blowing furnace is collected, condensed, and purified to obtain the arsenic substance.

[0025] The method for recovering valuable elements from high-copper, high-arsenic, and high-nickel wastewater by controlled potential stepwise recovery proposed in the present invention has the following advantages over the prior art:

[0026] 1. The present invention filters high-copper, high-arsenic, and high-nickel wastewater, and then uses sodium thiosulfate to carry out a first-stage sulfidation reaction to obtain a first-stage sulfided slag containing copper and a first-stage sulfided liquid; then adds a sulfiding agent to the first-stage sulfided liquid to carry out a second-stage sulfidation reaction to obtain a second-stage sulfided slag containing arsenic and a second-stage sulfided liquid; then adds an alkaline substance to the second-stage sulfided liquid to obtain a neutralized slag and a neutralized liquid; finally, the first-stage sulfided slag and the second-stage sulfided slag are leached, hydrolyzed in steps, and low-temperature cooked respectively to obtain copper and arsenic substances. The present invention has the advantages of simple operation, complete separation of copper, arsenic, and nickel, high recovery rate, short process, and good selective separation effect. The first-stage sulfided slag can be returned to the copper smelting process as high-quality copper concentrate, the second-stage sulfided slag can be returned to the arsenic recovery process as high-quality raw material, and the neutralized slag can be exported as an industrial product, thereby realizing the resource recovery of valuable elements in the high-copper, high-arsenic, and high-nickel wastewater.

[0027] 2. The present invention can precipitate copper, arsenic and nickel in a stepwise manner, which is beneficial to the reuse of wastewater and does not generate new wastewater, thereby reducing environmental pollution and being safe and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flowchart of the present invention;

[0029] Figure 2 This is a flowchart of a sulfide slag leaching process according to the present invention;

[0030] Figure 3 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Example 1

[0032] The present invention provides Figure 1-3 The method for recovering valuable elements from high-copper, high-arsenic, and high-nickel wastewater by controlling potential stepwise is shown, comprising the following steps:

[0033] S1. Filter the high-copper, high-arsenic, and high-nickel wastewater using a filtering device to remove suspended solids and particulate matter in the high-copper, high-arsenic, and high-nickel wastewater;

[0034] When filtering the high-copper, high-arsenic, and high-nickel wastewater, the wastewater is introduced into a filtering device, and suspended matter and particulate matter are intercepted by the filter medium in the filtering device. At the same time, the liquid is allowed to flow out through the filter medium, and the suspended matter and particulate matter accumulated on the filter medium are backwashed to flush the intercepted suspended matter and particulate matter out of the filter medium. After the filtration is completed, the waste residue generated during the filtration process is collected and the waste residue is treated as solid waste. By filtering the high-copper, high-arsenic, and high-nickel wastewater, the suspended matter and particulate matter in the high-copper, high-arsenic, and high-nickel wastewater can be effectively removed, providing a good foundation for subsequent deep treatment.

[0035] S2. Adding sodium thiosulfate to the filtered high-copper, high-arsenic, and high-nickel wastewater to carry out a temperature- and potential-controlled sulfidation reaction, separating the sulfided slag and the post-sulfidation liquid to obtain a copper-containing section of sulfided slag and a section of post-sulfidation liquid;

[0036] The sodium thiosulfate is in a solid or liquid state, and the conditions for adding sodium thiosulfate for the sulfidation reaction are: a reaction temperature of 50-100° C., a reaction time of 0.5-5 hours, a reaction endpoint potential of 200-300 mV, and a stirring device is required to stir the reaction liquid at a stirring speed of 100-600 r / min to increase the rate of the first stage sulfidation reaction.

[0037] S3, adding a sulfiding agent to the first-stage sulfided liquid to carry out a sulfidation reaction under temperature and potential control, and then separating the sulfided slag and the sulfided liquid to obtain arsenic-containing second-stage sulfided slag and second-stage sulfided liquid;

[0038] The sulfiding agent is set to be one or more of sodium sulfide, sodium hydrosulfide and hydrogen sulfide. The conditions of the sulfiding reaction after adding the sulfiding agent are: reaction temperature 10-40°C, reaction time 0.5-4h, reaction endpoint potential 50-180mV, stirring operation needs to be added during the reaction, and the stirring speed is 100-600r / min.

[0039] S4, adding alkaline substances to the liquid after the second stage sulfidation to carry out a neutralization reaction under temperature and potential control, and then separating the slag and the neutralization liquid to obtain nickel-containing neutralized slag;

[0040] The alkaline substance is set to one or more of sodium hydroxide, calcium hydroxide and potassium hydroxide. The neutralization solution needs to be stirred during the neutralization reaction. The conditions of the neutralization reaction are: reaction temperature 20-80°C, reaction time 0.5-3h, stirring speed 100-600r / min, and reaction endpoint potential -100-30mV.

[0041] S5. Leaching the first-stage sulfide slag and the second-stage sulfide slag with chloride salt to obtain a first-stage leachate and a second-stage leachate respectively;

[0042] The chloride salt is set to sodium chloride or calcium chloride, and the leaching treatment of the first-stage sulfide slag includes the following steps:

[0043] A1. Mix a section of sulfide slag with chloride salt to form a slurry;

[0044] A2. Add the slurry to a leaching tank, maintain the temperature at 50-90°C and stir, and introduce air or chlorine gas for oxidation, so that copper and arsenic are dissolved into the solution in the form of chlorides;

[0045] A3. After leaching the solution for 10-20 hours, separate the solid residue and the leachate by filtration or sedimentation to obtain a leachate;

[0046] The leaching treatment method of the second-stage sulfide slag is the same as that of the first-stage sulfide slag, specifically: first, the arsenic-containing second-stage sulfide slag is mixed with a chloride salt to form a slurry, and then, under appropriate temperature and stirring conditions, the slurry is added to a leaching tank, the temperature is maintained at 50-90°C and stirred, and air or chlorine is introduced for oxidation, so that copper and arsenic are dissolved in the solution in the form of chlorides; after leaching the solution for 10-20 hours to ensure maximum extraction of copper and arsenic, after completion of leaching, the solid residue and the leachate are separated by filtration or sedimentation to obtain the second-stage leachate.

[0047] S6. Hydrolyzing the first-stage leachate and the second-stage leachate in steps, and then respectively performing low-temperature blowing on the first-stage precipitate and the second-stage precipitate after the hydrolysis to obtain copper substances and arsenic substances.

[0048] During the step-by-step hydrolysis of the first-stage leachate, the pH value of the first-stage leachate is adjusted to 6-8 according to the chemical properties of copper, and then sodium hydroxide is added for hydrolysis reaction to form a copper-containing hydroxide precipitate, namely the first-stage precipitate. During the low-temperature blowing of the first-stage precipitate, the first-stage precipitate is fed into a blowing furnace, the temperature of the blowing furnace is controlled at 1200° C.-1400° C., coke or charcoal is used as a reducing agent, and the blowing furnace is placed in a reducing atmosphere, so that the copper compound is reduced and exists in the form of dust. Finally, the dust is collected and the collected dust is subjected to copper purification treatment.

[0049] During the step-by-step hydrolysis of the second-stage leachate, the pH value of the second-stage leachate is adjusted to 2-4 according to the chemical properties of arsenic to precipitate arsenic, and then sodium hydroxide is added to carry out a hydrolysis reaction to form a hydroxide precipitate containing arsenic. The hydroxide precipitate containing arsenic is the second-stage precipitate. During the low-temperature blowing of the second-stage precipitate, the second-stage precipitate is fed into a blowing furnace at a temperature of 400-550°C, and the arsenic compound is reduced using coke or charcoal as a reducing agent, so that the arsenic exists in the blowing furnace in the form of vapor. The vapor in the blowing furnace is collected, condensed, and purified to obtain the arsenic substance. Example 2

[0050] According to the method provided in Example 1, the valuable element recovery operation is actually performed for the first time on the high-copper, high-arsenic, and high-nickel wastewater. The specific steps are as follows:

[0051] 1. First, filter the high-copper, high-arsenic, and high-nickel wastewater. The copper (Cu), arsenic (As), and nickel (Ni) components in the filtered high-copper, high-arsenic, and high-nickel wastewater are shown in Table 1 below:

[0052] Table 1

[0053] Element type Cu As Ni Content (g / L) 48.37 28.22 18.87

[0054] 2. Sodium thiosulfate solid was added to the filtered high-copper, high-arsenic, and high-nickel wastewater for sulfidation reaction. The reaction temperature was 90°C, the reaction time was 4 hours, the stirring speed was 300 r / min, and the reaction endpoint potential was 300 mV. After filtration, a section of sulfided slag and a section of sulfided liquid were obtained. The section of sulfided slag was treated through steps S4 and S5. The (Cu), arsenic (As), and nickel (Ni) components of the section of sulfided liquid are shown in Table 2 below:

[0055] Table 2

[0056] Element type Cu As Ni Content (g / L) 0.53 23.98 17.89

[0057] According to the above table and the recovery rate of copper sulfide in the first stage, it is 98.9%, which is greater than 90%. The liquid after the first stage of sulfidation enters the next process.

[0058] 3. Sodium sulfide was added to the first-stage sulfided liquid to carry out a second-stage sulfidation reaction. The reaction temperature was 40°C, the reaction time was 4 hours, the stirring speed was 300 r / min, and the reaction endpoint potential was 180 mV. The sulfidation reaction liquid was filtered to obtain second-stage sulfided slag and second-stage sulfided liquid. The second-stage sulfided slag was treated through steps S4 and S5. The (Cu), arsenic (As) and nickel (Ni) components in the second-stage sulfided liquid are shown in Table 3 below:

[0059] Table 3

[0060] Element type Cu As Ni Content (g / L) 0.23 0.77 14.31

[0061] It can be seen from the above table that the recovery rate of the second-stage arsenic sulfide is 96.9%, which is greater than 90%. The liquid after the second-stage sulfidation enters the next process.

[0062] 4. Sodium hydroxide was added to the liquid after the second stage sulfidation for neutralization reaction. The reaction temperature was 20°C, the reaction time was 3 hours, the stirring speed was 300 r / min, and the reaction endpoint potential was 30 mV. The neutralization reaction liquid was filtered to obtain the neutralization slag and the neutralized liquid. The (Cu), arsenic (As) and nickel (Ni) components in the neutralized liquid are shown in Table 4 below:

[0063] Table 4

[0064] Element type Cu As Ni Content (g / L) 0.21 0.36 0.34

[0065] As shown in the table, the nickel recovery rate after three-stage neutralization is 97.6%, exceeding 90%. The neutralization residue can be exported as high-quality nickel raw material, and the neutralized liquid is sent to the wastewater treatment process.

[0066] In the entire process, the copper recovery rate in the first stage is 98.9%, the arsenic recovery rate in the second stage is 96.9%, and the nickel recovery rate in the third stage is 97.6%. Moreover, the extraction can be carried out in stages with good selectivity, which effectively solves the dispersion problem in the process of re-separation and extraction of valuable elements. Example 3

[0067] According to the method provided in Example 1, the valuable element recovery operation is actually performed for the second time on the high-copper, high-arsenic, and high-nickel wastewater. The specific steps are as follows:

[0068] 1. First, filter the high-copper, high-arsenic, and high-nickel wastewater. The copper (Cu), arsenic (As), and nickel (Ni) components in the filtered high-copper, high-arsenic, and high-nickel wastewater are shown in Table 5 below:

[0069] Form 5

[0070] Element type Cu As Ni Content (g / L) 44.26 23.10 17.42

[0071] 2. Sodium thiosulfate liquid was added to the filtered high-copper, high-arsenic, and high-nickel wastewater for sulfidation reaction. The reaction temperature was 50°C, the reaction time was 2 hours, the stirring speed was 500 r / min, and the reaction endpoint potential was 250 mV. After filtration, a section of sulfided slag and a section of sulfided liquid were obtained. The section of sulfided slag was treated through steps S4 and S5. The (Cu), arsenic (As), and nickel (Ni) components of the section of sulfided liquid are shown in Table 6 below:

[0072] Table 6

[0073] Element type Cu As Ni Content (g / L) 0.43 20.16 16.58

[0074] According to the above table and the recovery rate of copper sulfide in the first stage, it is 99.1%, which is greater than 90%. The liquid after the first stage of sulfidation enters the next process.

[0075] 3. Sodium hydrosulfide was added to the first-stage sulfided liquid to carry out a second-stage sulfidation reaction. The reaction temperature was 20°C, the reaction time was 3 hours, the stirring speed was 400 r / min, and the reaction endpoint potential was 100 mV. The sulfidation reaction liquid was filtered to obtain second-stage sulfided slag and second-stage sulfided liquid. The second-stage sulfided slag was treated through steps S4 and S5. The (Cu), arsenic (As) and nickel (Ni) components in the second-stage sulfided liquid are shown in Table 7 below:

[0076] Form 7

[0077] Element type Cu As Ni Content (g / L) 0.36 0.48 13.11

[0078] It can be seen from the above table that the recovery rate of the second-stage arsenic sulfide is 97.6%, which is greater than 90%. The liquid after the second-stage sulfidation enters the next process.

[0079] 4. Calcium hydroxide was added to the second-stage sulfided liquid for neutralization reaction. The reaction temperature was 50°C, the reaction time was 2 h, the stirring speed was 400 r / min, and the reaction endpoint potential was -50 mV. The neutralization reaction liquid was filtered to obtain neutralization slag and neutralization liquid. The (Cu), arsenic (As) and nickel (Ni) components in the neutralization liquid are shown in Table 8 below:

[0080] Form 8

[0081] Element type Cu As Ni Content (g / L) 0.21 0.19 0.43

[0082] As shown in the table, the nickel recovery rate after three-stage neutralization is 96.7%, exceeding 90%. The neutralization residue can be exported as high-quality nickel raw material, and the neutralized liquid is sent to the wastewater treatment process.

[0083] In the entire process, the copper recovery rate in the first stage is 99.1%, the arsenic recovery rate in the second stage is 97.6%, and the nickel recovery rate in the third stage is 96.7%. Moreover, it can be extracted in stages with good selectivity, which effectively solves the dispersion problem in the process of re-separation and extraction of valuable elements. Example 4

[0084] According to the method provided in Example 1, the valuable element recovery operation is actually performed for the third time on the high-copper, high-arsenic, and high-nickel wastewater. The specific steps are as follows:

[0085] 1. First, filter the high-copper, high-arsenic, and high-nickel wastewater. The copper (Cu), arsenic (As), and nickel (Ni) components in the filtered high-copper, high-arsenic, and high-nickel wastewater are shown in Table 9 below:

[0086] Form 9

[0087] Element type Cu As Ni Content (g / L) 46.31 25.69 17.07

[0088] 2. Sodium thiosulfate liquid was added to the filtered high-copper, high-arsenic, and high-nickel wastewater for sulfidation reaction. The reaction temperature was 50°C, the reaction time was 1 hour, the stirring speed was 500 r / min, and the reaction endpoint potential was 200 mV. After filtration, a section of sulfided slag and a section of sulfided liquid were obtained. The section of sulfided slag was treated through steps S4 and S5. The (Cu), arsenic (As), and nickel (Ni) components of the section of sulfided liquid are shown in Table 10 below:

[0089] Form 10

[0090] Element type Cu As Ni Content (g / L) 0.32 20.65 15.44

[0091] According to the above table and the recovery rate of copper sulfide in the first stage, it is 99.3%, which is greater than 90%. The liquid after the first stage of sulfidation enters the next process.

[0092] 3. Hydrogen sulfide was added to the first-stage sulfided liquid to carry out a second-stage sulfidation reaction. The reaction temperature was 10°C, the reaction time was 2 hours, the stirring speed was 500 r / min, and the reaction endpoint potential was 50 mV. The sulfidation reaction liquid was filtered to obtain second-stage sulfided slag and second-stage sulfided liquid. The second-stage sulfided slag was treated through steps S4 and S5. The (Cu), arsenic (As), and nickel (Ni) components in the second-stage sulfided liquid are shown in Table 11 below:

[0093] Form 11

[0094] Element type Cu As Ni Content (g / L) 0.23 0.28 13.18

[0095] It can be seen from the above table that the recovery rate of the second-stage arsenic sulfide is 98.6%, which is greater than 90%. The liquid after the second-stage sulfidation enters the next process.

[0096] 4. Potassium hydroxide was added to the liquid after the second stage sulfidation for neutralization reaction. The reaction temperature was 80°C, the reaction time was 2 hours, the stirring speed was 500 r / min, and the reaction endpoint potential was -100 mV. The neutralization reaction liquid was filtered to obtain neutralization slag and neutralization liquid. The (Cu), arsenic (As) and nickel (Ni) components in the neutralization liquid are shown in Table 12 below:

[0097] Form 12

[0098] Element type Cu As Ni Content (g / L) 0.21 0.26 0.24

[0099] As shown in the table, the nickel recovery rate after three-stage neutralization is 98.2%, exceeding 90%. The neutralization residue can be exported as high-quality nickel raw material, and the neutralized liquid is sent to the wastewater treatment process.

[0100] In the entire process, the copper recovery rate in the first stage is 99.3%, the arsenic recovery rate in the second stage is 98.6%, and the nickel recovery rate in the third stage is 98.2%. Moreover, the extraction can be carried out in stages with good selectivity, which effectively solves the dispersion problem in the process of re-separation and extraction of valuable elements.

[0101] In summary, by filtering high-copper, high-arsenic, and high-nickel wastewater, and then using sodium thiosulfate to carry out a first-stage sulfidation reaction, a copper-containing first-stage sulfided slag and a first-stage sulfided liquid are obtained; a sulfiding agent is then added to the first-stage sulfided liquid to carry out a second-stage sulfidation reaction, and arsenic-containing second-stage sulfided slag and a second-stage sulfided liquid are obtained; an alkaline substance is then added to the second-stage sulfided liquid to obtain a neutralized slag and a neutralized liquid, and finally the first-stage sulfided slag and the second-stage sulfided slag are subjected to leaching treatment, step-by-step hydrolysis, and low-temperature cooking, respectively, to obtain copper and arsenic substances. The method has the advantages of simple operation, thorough separation of copper, arsenic and nickel, high recovery rate, short process and good selective separation effect. The first-stage sulfide slag can be returned to the copper smelting process as high-quality copper concentrate, the second-stage sulfide slag can be returned to the arsenic recovery process as high-quality raw material, and the neutralized slag can be exported as an industrial product, realizing the resource recovery of valuable elements in high-copper, high-arsenic and high-nickel wastewater. The method can cascade the precipitation of copper, arsenic and nickel, which is beneficial to the reuse of wastewater, does not generate new wastewater, reduces environmental pollution, and is safe and environmentally friendly.

[0102] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, 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 high-copper, high-arsenic, and high-nickel wastewater by controlled potential stepwise recovery, characterized by: The steps include: S1. Filter the high-copper, high-arsenic, and high-nickel wastewater using a filtering device to remove suspended solids and particulate matter in the high-copper, high-arsenic, and high-nickel wastewater; S2. Adding sodium thiosulfate to the filtered high-copper, high-arsenic, and high-nickel wastewater to carry out a temperature- and potential-controlled sulfidation reaction, separating the sulfided slag and the sulfided liquid to obtain a copper-containing section of sulfided slag and a section of sulfided liquid; the conditions for adding sodium thiosulfate for the sulfidation reaction are: a reaction temperature of 50-100° C., a reaction time of 0.5-5 h, a reaction endpoint potential of 200-300 mV, and a stirring device is required to stir the reaction liquid at a stirring speed of 100-600 r / min; S3, adding a vulcanizing agent to the first stage vulcanized liquid to carry out a temperature-controlled and potential-controlled vulcanization reaction, and then separating the sulfided slag and the vulcanized liquid to obtain arsenic-containing second stage vulcanized slag and second stage vulcanized liquid, wherein the conditions for the vulcanization reaction after adding the vulcanizing agent are: reaction temperature 10-40° C., reaction time 0.5-4 h, reaction endpoint potential 50-180 mV, stirring operation needs to be added during the reaction, and the stirring speed is 100-600 r / min; S4. Adding alkaline substances to the liquid after the second stage of sulfidation to carry out a neutralization reaction under temperature and potential control, and then separating the slag and the neutralization liquid to obtain nickel-containing neutralized slag. The conditions of the neutralization reaction are: reaction temperature 20-80°C, reaction time 0.5-3h, stirring speed 100-600r / min, and reaction endpoint potential -100-30mV; S5. Leaching the first-stage sulfide slag and the second-stage sulfide slag with chloride salt to obtain a first-stage leachate and a second-stage leachate respectively; S6, hydrolyzing the first-stage leachate and the second-stage leachate in steps, and then respectively performing low-temperature blowing on the first-stage precipitate and the second-stage precipitate after the hydrolysis to obtain copper substances and arsenic substances; When the first stage leachate is subjected to step-by-step hydrolysis, the pH value of the first stage leachate is adjusted to 6-8 according to the chemical properties of copper, and then sodium hydroxide is added to carry out a hydrolysis reaction to form a copper-containing hydroxide precipitate, which is the first stage precipitate; When the first stage precipitate is subjected to low-temperature blowing, the first stage precipitate is fed into a blowing furnace, the temperature of the blowing furnace is controlled at 1200° C. to 1400° C., coke or charcoal is used as a reducing agent, the blowing furnace is placed in a reducing atmosphere, the copper compound is reduced and exists in the form of dust, and finally the dust is collected and the collected dust is subjected to copper purification treatment; During the step-by-step hydrolysis of the second-stage leachate, the pH value of the second-stage leachate is adjusted to 2-4 according to the chemical properties of arsenic to precipitate arsenic, and then sodium hydroxide is added to carry out a hydrolysis reaction to form a hydroxide precipitate containing arsenic. The hydroxide precipitate containing arsenic is the second-stage precipitate.

2. The method for recovering valuable elements from high-copper, high-arsenic, and high-nickel wastewater by controlled potential stepwise recovery according to claim 1, characterized in that: In step S1, when filtering the high-copper, high-arsenic, and high-nickel wastewater, the wastewater is introduced into the filtering equipment, and the suspended matter and particulate matter are intercepted by the filter medium in the filtering equipment. At the same time, the liquid is allowed to flow out through the filter medium, and the suspended matter and particulate matter accumulated on the filter medium are backwashed to flush the intercepted suspended matter and particulate matter from the filter medium. After the filtration is completed, the waste residue generated during the filtration process is collected and the waste residue is treated as solid waste.

3. The method for recovering valuable elements from high-copper, high-arsenic, and high-nickel wastewater by controlled potential stepwise recovery according to claim 2, characterized in that: In step S2, the sodium thiosulfate is in a solid or liquid form.

4. The method for recovering valuable elements from high-copper, high-arsenic, and high-nickel wastewater by controlled potential stepwise recovery according to claim 3, characterized in that: In step S3, the sulfiding agent is set to be one or more of sodium sulfide, sodium hydrosulfide and hydrogen sulfide.

5. The method for recovering valuable elements from high-copper, high-arsenic, and high-nickel wastewater by controlled potential stepwise recovery according to claim 4, characterized in that: In step S4, the alkaline substance is set to one or more of sodium hydroxide, calcium hydroxide and potassium hydroxide, and the neutralization solution needs to be stirred during the neutralization reaction.

6. The method for recovering valuable elements from high-copper, high-arsenic, and high-nickel wastewater by controlled potential stepwise recovery according to claim 5, characterized in that: In step S5, the chloride salt is set to sodium chloride or calcium chloride, and the leaching treatment of the first stage sulfide slag includes the following steps: A1. Mix a section of sulfide slag with chloride salt to form a slurry; A2. Add the slurry to a leaching tank, maintain the temperature at 50-90°C and stir, and introduce air or chlorine gas for oxidation, so that copper and arsenic are dissolved into the solution in the form of chlorides; A3. After leaching the solution for 10-20 hours, separate the solid residue and the leachate by filtration or sedimentation to obtain a leachate; The leaching treatment method of the second-stage sulfide slag is the same as the leaching treatment method of the first-stage sulfide slag to obtain the second-stage leachate.

7. The method for recovering valuable elements from high-copper, high-arsenic, and high-nickel wastewater by controlled potential stepwise recovery according to claim 6, characterized in that: When the second-stage precipitate is subjected to low-temperature blowing, the second-stage precipitate is fed into a blowing furnace at a temperature of 400-550° C., and coke or charcoal is used as a reducing agent to reduce the arsenic compound so that the arsenic exists in the blowing furnace in the form of steam. The steam in the blowing furnace is collected, condensed, and purified to obtain the arsenic substance.

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