A process for the recovery of nickel salts from copper sulfate production wastewater by fractional precipitation

Abstract

The present application relates to the technical field of industrial wastewater pollution treatment, and particularly discloses a new method for recovering nickel salt from copper sulfate production wastewater by using a segmented precipitation method, which adopts a first-stage sulfuration to remove copper and arsenic, a second-stage sulfuration to remove arsenic, and a third-stage neutralization to precipitate nickel, so as to realize the selective recovery of valuable elements, solve the dispersion problem in the process of re-separation and extraction of valuable elements, reduce the content of impurities in the neutralization slag, improve the quality of the neutralization slag, and realize the recycling of valuable elements in high-copper, high-arsenic and high-nickel wastewater, thus achieving important economic, environmental and social benefits.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of industrial wastewater pollution treatment, and particularly relates to a new method for recovering nickel salt from copper sulfate production wastewater by a step-by-step precipitation method. BACKGROUND

[0002] The copper sulfate production wastewater is washing water in the process of producing refined copper sulfate crystal products and washing water of related equipment and pipelines. Since the coarse copper sulfate crystal is obtained by concentrating copper electrolyte, the coarse copper sulfate crystal carries part of impurities such as arsenic and nickel. In order to improve the quality of refined copper sulfate, the production wastewater must be discharged, which causes the high-value nickel element in the wastewater to be taken away together. With the increase of the processing amount of crude copper, the total amount of nickel taken away increases, which causes a large amount of resource waste.

[0003] The existing traditional nickel recovery process first carries out one-time diffusion dialysis deacidification and dearsenification on the nickel-containing waste liquid, then carries out neutralization de-coppering and dearsenification on the one-time diffusion residual liquid, and then deeply neutralizes to extract high-copper, high-arsenic and high-nickel slag. The high-nickel slag is used as a raw material for extracting nickel. Since the nickel-containing material contains copper, arsenic and other impurities, the main grade of nickel is low, which causes a long nickel product extraction process, large alkali consumption, complex process, and large discount of the direct recovery rate and the recovery rate of nickel. Therefore, a new method for recovering nickel salt from copper sulfate production wastewater by a step-by-step precipitation method is needed to solve the above problems and effectively improve the direct recovery rate and the recovery rate of nickel. SUMMARY

[0004] The purpose of the present application is to provide a new method for recovering nickel salt from copper sulfate production wastewater by a step-by-step precipitation method to solve the problem of low work efficiency and large waste of manpower in the prior art in the background.

[0005] To achieve the above purpose, the technical scheme is as follows:

[0006] A new method for recovering nickel salt from copper sulfate production wastewater by a step-by-step precipitation method, comprising the following steps:

[0007] S1, adding a sulfidation agent to the copper sulfate production wastewater to enable the copper sulfate production wastewater to perform a sulfidation reaction, filtering and washing after the reaction is completed, and obtaining a first sulfidation residue containing copper and arsenic and a first sulfidation liquid;

[0008] S2, adding a sulfidation agent to the first sulfidation liquid again to enable the first sulfidation liquid to perform a sulfidation reaction, filtering and washing after the reaction is completed, and obtaining a second sulfidation residue containing arsenic and a second sulfidation liquid;

[0009] S3, adding lye to the second-stage post-sulfuration liquid to make the second-stage post-sulfuration liquid perform a neutralization reaction, and then performing filtration and washing after the reaction is completed to obtain a nickel-containing neutralized residue and a post-neutralization liquid.

[0010] Preferably, in step S1, the copper sulfate production wastewater contains copper at a content of 23-24 g / L, arsenic at a content of 3-4 g / L, and nickel at a content of 2-3 g / L, and the content of the sulfuration agent added in the copper sulfate production wastewater is 12-13 g / L.

[0011] Preferably, the sulfuration agent is one or more of sodium thiosulfate, sodium sulfide, sodium hydrosulfide, and hydrogen sulfide.

[0012] Preferably, the copper sulfate production wastewater needs to be stirred when performing the sulfuration reaction, the stirring speed is 100-600 r / min, the sulfuration reaction temperature is 20-100℃, the reaction time is 2-6 h, and the reaction end-point potential is 200-300 mV.

[0013] Preferably, when the reaction liquid after the sulfuration reaction of the copper sulfate production wastewater is filtered and washed, the mixed liquid after the sulfuration reaction is first subjected to solid-liquid separation through a filtering device, and then the solid substance is washed with a washing liquid for 2-3 times, each time of washing needs to be subjected to solid-liquid separation, and the liquid after washing and the separated liquid are mixed, which is the first-stage post-sulfuration liquid, and the separated solid is a first-stage sulfuration residue containing copper and arsenic, which is transferred to a smelting production system for smelting and copper recovery.

[0014] Preferably, in step S2, the reaction temperature of the first-stage post-sulfuration liquid in the sulfuration reaction is 30-90℃, the reaction time is 1-5 h, the stirring speed is 100-600 r / min, the reaction end-point potential is 0-180 mV, and the content of the sulfuration agent added in the first-stage post-sulfuration liquid is 0.5-0.65 g / L.

[0015] Preferably, the filtering and washing of the sulfuration reaction liquid of the first-stage post-sulfuration liquid are the same as the filtering and washing of the sulfuration reaction liquid of the copper sulfate production wastewater, and the obtained second-stage sulfuration residue is subjected to an arsenic recovery process.

[0016] Preferably, in step S3, the lye is one or more of sodium hydroxide, calcium hydroxide, and potassium hydroxide.

[0017] Preferably, the reaction temperature of the second-stage post-sulfuration liquid in the neutralization reaction is 40-90℃, the reaction time is 1-3 h, the stirring speed is 100-600 r / min, the reaction end-point pH is 7-14, and the usage ratio of the lye to the second-stage post-sulfuration liquid is 1:1.

[0018] Preferably, the filtration and washing mode of the neutralized reaction liquid after the two-stage sulfidation is also the same as that of the sulfidation reaction liquid of the copper sulfate production wastewater, and the neutralized residue is a nickel raw material, and the neutralized liquid is treated in the wastewater treatment process.

[0019] The present application provides a new method for recovering nickel salt from copper sulfate production wastewater by a step-by-step precipitation method, which has the following advantages compared with the prior art:

[0020] 1. The present application adopts a one-stage sulfidation to remove copper and arsenic, a two-stage sulfidation to remove arsenic, and a three-stage neutralization to precipitate nickel, which has good selectivity, solves the dispersion problem in the process of re-separation and extraction of valuable elements, reduces the content of impurities in the neutralized residue, improves the quality of the neutralized residue, and has the advantages of simple operation, easy industrialization, realization of resource recovery of valuable elements in high-copper, high-arsenic and high-nickel wastewater, and important economic, environmental and social benefits.

[0021] 2. The present application adds a sulfidation agent to the copper sulfate production wastewater to enable the copper sulfate production wastewater to undergo a sulfidation reaction, and then filters and washes after the reaction is completed, which can make the recovery rate of copper in the first stage reach 93.17%, greatly improving the recovery rate of copper.

[0022] 3. The present application adds a sulfidation agent to the first-stage sulfidation liquid to make the first-stage sulfidation liquid undergo a sulfidation reaction, and then filters and washes after the reaction is completed, which can make the recovery rate of arsenic in the second stage reach 91.13%, effectively improving the recovery rate of arsenic.

[0023] 4. The present application adds an alkali solution to the second-stage sulfidation liquid to make the second-stage sulfidation liquid undergo a neutralization reaction, and then filters and washes after the reaction is completed, which can make the recovery rate of nickel in the third stage reach 97.44%, improving the purity of the neutralized residue. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The flowchart of the present application is shown in the figure;

[0025] Figure 2 The flowchart of the present application is shown in the figure. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. The specific embodiments described herein are only used to explain the present application, and are not used to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application. Example 1

[0027] The application provides a new method for recovering nickel salt from copper sulfate production wastewater by a fractional precipitation method as shown in the formula (I). Figures 1-2 The new method for recovering nickel salt from copper sulfate production wastewater by a fractional precipitation method comprises the following steps:

[0028] S1, a sulfidation agent is added into the copper sulfate production wastewater, so that the copper sulfate production wastewater can be subjected to a sulfidation reaction, and after the reaction is completed, filtration and washing are performed to obtain a first sulfidation residue containing copper and arsenic and a first sulfidation liquid;

[0029] The copper sulfate production wastewater contains copper at a content of 23-24 g / L, arsenic at a content of 3-4 g / L, and nickel at a content of 2-3 g / L, and the content of the sulfidation agent added into the copper sulfate production wastewater is 12-13 g / L.

[0030] The sulfidation agent is one or more of sodium thiosulfate, sodium sulfide, sodium hydrosulfide and hydrogen sulfide, wherein the sodium thiosulfate is obtained by reacting sulfur with sodium sulfite. The specific steps are as follows:

[0031] 1) sulfur powder is added into a dilute caustic solution and stirred until completely dissolved.

[0032] 2) a sulfite solution is slowly added to generate sodium thiosulfate precipitate.

[0033] 3) the precipitate is filtered and washed to obtain sodium thiosulfate.

[0034] The sodium sulfide is obtained by reacting sulfur and sodium hydroxide. The specific steps are as follows:

[0035] A1, sulfur is reacted with a sodium hydrate solution to generate sodium sulfide and water:

[0036] S+2NaOH->Na2S+H2O

[0037] A2, the sodium sulfide solution is filtered and crystallized, and then dried to obtain solid sodium sulfide.

[0038] The sodium hydrosulfide is obtained by reacting sodium sulfide and acid. The specific steps are as follows:

[0039] B1, sodium sulfide is reacted with acid (such as hydrochloric acid) to generate sodium hydrosulfide and corresponding salt:

[0040] Na2S+2HCl->NaHS+H2S+NaCl

[0041] B2, the generated sodium hydrosulfide solution is filtered and crystallized or concentrated to obtain solid sodium hydrosulfide.

[0042] The hydrogen sulfide is generated by reacting acid and sulfide. The specific steps are as follows:

[0043] C1, a sulfide (such as iron sulfide or sodium sulfide) is reacted with an acid (such as hydrochloric acid or sulfuric acid) to produce hydrogen sulfide gas:

[0044] FeS + 2HCl -> H2S + FeCl2

[0045] C2, the gas can be collected and treated by passing into water or by an absorption bottle.

[0046] The copper sulfate production wastewater needs to be stirred when the sulfidation reaction is carried out, the stirring speed is 100-600 r / min, the temperature of the sulfidation reaction is 20-100℃, the reaction time is 2-6h, and the reaction end potential is 200-300mV.

[0047] When the reaction liquid after the sulfidation reaction of the copper sulfate production wastewater is filtered and washed, the mixed liquid after the sulfidation reaction is first subjected to solid-liquid separation through a filtering device, and then the solid substance is washed with a washing liquid for 2-3 times, each time of washing needs to be subjected to solid-liquid separation, and the washed liquid and the separated liquid are mixed, which is a first-stage sulfidation liquid, and the separated solid is a first-stage sulfidation residue containing copper and arsenic, the first-stage sulfidation residue is transferred to a smelting production system for smelting and recovery of copper, and the recovery rate of copper in the treated copper sulfate production wastewater is greater than 90%.

[0048] S2, a sulfidation agent is added to the first-stage sulfidation liquid again, so that the first-stage sulfidation liquid is subjected to a sulfidation reaction, and then filtering and washing are carried out after the reaction is completed, to obtain a second-stage sulfidation residue containing arsenic and a second-stage sulfidation liquid.

[0049] The reaction temperature of the first-stage sulfidation liquid is 30-90℃, the reaction time is 1-5h, the stirring speed is 100-600 r / min, the reaction end potential is 0-180mV, and the content of the sulfidation agent added to the first-stage sulfidation liquid is 0.5-0.65g / L.

[0050] The filtering and washing of the sulfidation reaction liquid of the first-stage sulfidation liquid are the same as those of the filtering and washing of the sulfidation reaction liquid of the copper sulfate production wastewater, and will not be described in detail here, the obtained second-stage sulfidation residue is subjected to an arsenic recovery process, and the recovery rate of arsenic in the treated first-stage sulfidation liquid is greater than 90%.

[0051] S3, an alkali liquid is added to the second-stage sulfidation liquid, so that the second-stage sulfidation liquid is subjected to a neutralization reaction, and then filtering and washing are carried out after the reaction is completed, to obtain a neutralization residue containing nickel and a neutralized liquid.

[0052] The alkali liquid is set to one or more of sodium hydroxide, calcium hydroxide and potassium hydroxide.

[0053] The reaction temperature of the neutralization reaction of the second-stage sulfidation liquid is 40-90℃, the reaction time is 1-3h, the stirring speed is 100-600r / min, the reaction end point pH is 7-14, and the use ratio of the alkali liquid to the second-stage sulfidation liquid is 1:1.

[0054] The filtering and washing mode of the neutralized reaction liquid of the second-stage sulfidation liquid is the same as that of the filtering and washing mode of the sulfidation reaction liquid of the copper sulfate production wastewater, and will not be described in detail here. The obtained neutralized residue is a nickel raw material, and the obtained post-neutralization liquid enters the wastewater treatment process for wastewater treatment. The recovery rate of nickel in the second-stage sulfidation post-neutralization liquid after treatment is greater than 90%. Example 2

[0055] The method provided in Example 1 is used to recover the actual nickel salt from the copper sulfate production wastewater, and the specific process is as follows:

[0056] S1, sodium sulfide is added to the copper sulfate production wastewater to enable the copper sulfate production wastewater to undergo sulfidation reaction. The reaction temperature is 20℃, the reaction time is 6h, the stirring speed is 300r / min, and the reaction end point potential is 300mV. After the reaction is completed, filtering and washing are performed to obtain a first-stage sulfidation residue containing copper and arsenic and a first-stage sulfidation post-neutralization liquid;

[0057] The content of copper (Cu), arsenic (As) and nickel (Ni) in the copper sulfate production wastewater is as shown in Table 1 below:

[0058] Table 1

[0059] Element class Cu As Ni Content (g / L) 23.46 3.08 2.22

[0060] The content of copper (Cu), arsenic (As) and nickel (Ni) in the obtained first-stage sulfidation post-neutralization liquid is as shown in Table 2 below:

[0061] Table 2

[0062] Element class Cu As Ni Content (g / L) 1.32 2.96 2.09

[0063] From the data in the above copper sulfate production wastewater composition table and the first-stage sulfidation post-neutralization liquid composition table, it can be concluded that the recovery rate of the first-stage sulfidation copper is 93.17%, which is greater than 90%. The first-stage sulfidation residue can be used as high-quality copper-containing material and enters the smelting production system, and the first-stage sulfidation post-neutralization liquid enters the next process.

[0064] S2, sodium sulfide is added to the first-stage sulfidation post-neutralization liquid to enable the first-stage sulfidation post-neutralization liquid to undergo sulfidation reaction. The reaction temperature is 30℃, the reaction time is 5h, the stirring speed is 300r / min, the reaction end point potential is 180mV, and filtering and washing are performed after the reaction is completed to obtain a second-stage sulfidation residue containing arsenic and a second-stage sulfidation post-neutralization liquid;

[0065] The content of copper (Cu), arsenic (As) and nickel (Ni) in the obtained second-stage sulfidation post-liquid is as shown in Table 3:

[0066] Table 3

[0067] Element class Cu As Ni Content (g / L) 0.31 0.27 1.86

[0068] From the second-stage sulfidation post-liquid component table, it can be seen that the recovery rate of arsenic in the second-stage sulfidation is 91.13%, which is greater than 90%. The second-stage sulfidation residue can be used as a high-quality raw material in the arsenic recovery process, and the second-stage sulfidation post-liquid enters the next process.

[0069] S3, sodium hydroxide is added to the second-stage sulfidation post-liquid to make the second-stage sulfidation post-liquid undergo a neutralization reaction, the reaction temperature is 40°C, the reaction time is 3h, the stirring speed is 300r / min, the reaction endpoint pH is 7, and after the reaction is completed, filtration and washing are performed to obtain a nickel-containing neutralization residue and a post-neutralization liquid;

[0070] The content of copper (Cu), arsenic (As) and nickel (Ni) in the obtained post-neutralization liquid is as shown in Table 4:

[0071] Table 4

[0072] Element class Cu As Ni Content (g / L) 0.016 0.20 0.023

[0073] From the post-neutralization liquid component table, it can be seen that the recovery rate of nickel in the third-stage neutralization is 97.44%, which is greater than 90%. The neutralization residue can be sold as a high-quality nickel raw material, and the post-neutralization liquid enters the wastewater treatment process.

[0074] In the entire process, the recovery rate of copper in the first stage is 93.17%, the recovery rate of arsenic in the second stage is 91.13%, and the recovery rate of nickel in the third stage is 97.44%. Moreover, the valuable elements can be extracted in stages, which has good selectivity, solves the dispersion problem in the process of re-separation and extraction of valuable elements, reduces the content of impurities in the neutralization residue, and improves the quality of the neutralization residue. Example 3

[0075] The method provided in Example 1 is used to recover secondary actual nickel salt from copper sulfate production wastewater, and the specific process is as follows:

[0076] S1, sodium hydrosulfide is added to the copper sulfate production wastewater to enable the copper sulfate production wastewater to undergo a sulfidation reaction, the reaction temperature is 60°C, the reaction time is 4h, the stirring speed is 400r / min, the reaction endpoint potential is 250mV, and after the reaction is completed, filtration and washing are performed to obtain a copper and arsenic-containing first-stage sulfidation residue and a first-stage sulfidation post-liquid;

[0077] The content of copper (Cu), arsenic (As) and nickel (Ni) in the copper sulfate production wastewater is as shown in Table 5:

[0078] Table 5

[0079] Element class Cu As Ni Content (g / L) 23.22 3.16 2.31

[0080] The content of copper (Cu), arsenic (As) and nickel (Ni) in the obtained first-stage sulfidation liquid is as shown in Table 6 below:

[0081] Table 6

[0082] Element class Cu As Ni Content (g / L) 0.042 2.99 2.04

[0083] From the data of the copper sulfate production wastewater composition table and the first-stage sulfidation liquid composition table, it can be concluded that the recovery rate of the first-stage sulfidation copper is 98.89%, which is greater than 90%. The first-stage sulfidation residue can be used as high-quality copper-containing material to enter the smelting production system, and the first-stage sulfidation liquid enters the next process.

[0084] S2, hydrogen sulfide is added to the first-stage sulfidation liquid again, and the first-stage sulfidation liquid is subjected to a sulfidation reaction, the reaction temperature is 60°C, the reaction time is 3h, the stirring speed is 400r / min, the reaction endpoint potential is 100mV, and after the reaction is completed, filtration and washing are performed, obtaining a second-stage sulfidation residue containing arsenic and a second-stage sulfidation liquid;

[0085] The content of copper (Cu), arsenic (As) and nickel (Ni) in the obtained second-stage sulfidation liquid is as shown in Table 7 below:

[0086] Table 7

[0087] Element class Cu As Ni Content (g / L) 0.013 0.18 1.95

[0088] From the second-stage sulfidation liquid composition table, it can be concluded that the recovery rate of the second-stage sulfidation arsenic is 92.57%, which is greater than 90%. The second-stage sulfidation residue can be used as high-quality raw material to go to the arsenic recovery process, and the second-stage sulfidation liquid enters the next process.

[0089] S3, calcium hydroxide is added to the second-stage sulfidation liquid, and the second-stage sulfidation liquid is subjected to a neutralization reaction, the reaction temperature is 70°C, the reaction time is 2h, the stirring speed is 400r / min, the reaction endpoint pH is 10, and after the reaction is completed, filtration and washing are performed, obtaining a neutralization residue containing nickel and a neutralized liquid;

[0090] The content of copper (Cu), arsenic (As) and nickel (Ni) in the obtained neutralized liquid is as shown in Table 8 below:

[0091] Table 8

[0092] Element class Cu As Ni Content (g / L) 0.008 0.09 0.030

[0093] From the neutralization of the post-liquid composition table, the recovery rate of three-stage nickel is 97.18%, which is greater than 90%. The neutralization slag can be sold as high-quality nickel raw materials, and the post-neutralization liquid enters the wastewater treatment process.

[0094] The recovery rate of the whole process is 98.89% for the first-stage copper, 92.57% for the second-stage arsenic, and 97.18% for the third-stage nickel. The selective extraction can be performed in stages, and the dispersion problem in the re-separation and extraction process of valuable elements is well solved. The content of impurities in the neutralization slag is reduced, and the quality of the neutralization slag is improved. Example 4

[0095] The method provided in Example 1 is used to recover three actual nickel salts from copper sulfate production wastewater, and the specific process is as follows:

[0096] S1, hydrogen sulfide is added to the copper sulfate production wastewater to enable the copper sulfate production wastewater to undergo sulfidation reaction, the reaction temperature is 100°C, the reaction time is 2h, the stirring speed is 500r / min, and the reaction endpoint potential is 300mV. After the reaction is completed, filtration and washing are performed to obtain a first-stage sulfidation slag containing copper and arsenic and a first-stage sulfidation post-liquid;

[0097] The content of copper (Cu), arsenic (As) and nickel (Ni) components in the copper sulfate production wastewater is as follows in Table 9:

[0098] Table 9

[0099] Element class Cu As Ni Content (g / L) 23.02 3.26 2.13

[0100] The content of copper (Cu), arsenic (As) and nickel (Ni) components in the obtained first-stage sulfidation post-liquid is as follows in Table 10:

[0101] Table 10

[0102] Element class Cu As Ni Content (g / L) 0.012 2.88 2.01

[0103] From the above copper sulfate production wastewater composition table and the data of the first-stage sulfidation post-liquid composition table, the recovery rate of the first-stage sulfidation copper is 99.95%, which is greater than 90%. The first-stage sulfidation slag can be used as high-quality copper-containing materials to enter the smelting production system, and the first-stage sulfidation post-liquid enters the next process.

[0104] S2, sulfide acid is added to the first-stage sulfidation post-liquid to enable the first-stage sulfidation post-liquid to undergo sulfidation reaction, the reaction temperature is 90°C, the reaction time is 1h, the stirring speed is 500r / min, and the reaction endpoint potential is 180mV. After the reaction is completed, filtration and washing are performed to obtain a second-stage sulfidation slag containing arsenic and a second-stage sulfidation post-liquid;

[0105] The content of copper (Cu), arsenic (As) and nickel (Ni) in the obtained second-stage sulfidation post-liquid is shown in Table 11 below:

[0106] Table 11

[0107] Element class Cu As Ni Content (g / L) 0.011 0.15 1.92

[0108] It can be seen from the second-stage sulfidation post-liquid component table that the recovery rate of arsenic in the second-stage sulfidation is 95.4%, which is greater than 90%. The second-stage sulfidation residue can be used as a high-quality raw material in the arsenic recovery process, and the second-stage sulfidation post-liquid enters the next process.

[0109] S3, potassium hydroxide is added to the second-stage sulfidation post-liquid to perform a neutralization reaction, the reaction temperature is 80°C, the reaction time is 1h, the stirring speed is 500r / min, the reaction endpoint pH is 14, and after the reaction is completed, filtration and washing are performed to obtain a nickel-containing neutralization residue and a post-neutralization liquid;

[0110] The content of copper (Cu), arsenic (As) and nickel (Ni) in the obtained post-neutralization liquid is shown in Table 12 below:

[0111] Table 12

[0112] Element class Cu As Ni Content (g / L) Element class Cu As Ni Content (g / L) 0.007 0.08 0.020

[0113] It can be seen from the post-neutralization liquid component table that the recovery rate of nickel in the third-stage neutralization is 99.06%, which is greater than 90%. The neutralization residue can be sold as a high-quality nickel raw material, and the post-neutralization liquid enters the wastewater treatment process.

[0114] In the entire process, the recovery rate of copper in the first stage is 99.95%, the recovery rate of arsenic in the second stage is 95.4%, and the recovery rate of nickel in the third stage is 99.06%. Moreover, the valuable elements can be extracted in stages, with good selectivity, which solves the dispersion problem in the process of re-separation and extraction of valuable elements. The content of impurities in the neutralization residue is reduced, and the quality of the neutralization residue is improved.

[0115] In summary, by adopting the one-stage sulfidation to remove copper and arsenic, the two-stage sulfidation to remove arsenic, and the three-stage neutralization to precipitate nickel, the valuable elements can be extracted in stages with good selectivity, which solves the dispersion problem in the process of re-separation and extraction of valuable elements, reduces the content of impurities in the neutralization residue, and improves the quality of the neutralization residue. This method is simple to operate and easy to industrialize, realizes the resource recovery of valuable elements in high-copper, high-arsenic and high-nickel wastewater, and has important economic, environmental and social benefits.

[0116] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art will appreciate that the technical solutions described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalent features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for recovering nickel salts from copper sulfate production wastewater by a staged precipitation method, characterized in that: The steps include: S1. Add a sulfiding agent to the copper sulfate production wastewater to enable the copper sulfate production wastewater to undergo a sulfidation reaction. After the reaction is completed, filter and wash the wastewater to obtain a sulfided slag containing copper and arsenic and a post-sulfidation liquid; The copper sulfate production wastewater needs to be stirred during the sulfidation reaction, the stirring speed is 100-600r / min, the sulfidation reaction temperature is 20-100°C, the reaction time is 2-6h, and the reaction endpoint potential is 200-300mV; S2. Adding a sulfiding agent again to the first-stage sulfided liquid to cause a sulfidation reaction of the first-stage sulfided liquid. After the reaction is completed, filtering and washing are performed to obtain a second-stage sulfided slag containing arsenic and a second-stage sulfided liquid; The reaction temperature of the first stage post-sulfurization liquid for the sulfurization reaction is 30-90° C., the reaction time is 1-5 hours, the stirring speed is 100-600 r / min, the reaction endpoint potential is 0-180 mV, and the content of the sulfurizing agent added to the first stage post-sulfurization liquid is 0.5-0.65 g / L; S3, adding alkali solution to the second-stage sulfided liquid to neutralize the second-stage sulfided liquid, and filtering and washing after the reaction is completed to obtain nickel-containing neutralized slag and neutralized liquid; The reaction temperature of the neutralization reaction of the second-stage vulcanized liquid is 40-90° C., the reaction time is 1-3 hours, the stirring speed is 100-600 r / min, the pH value at the reaction end point is 7-14, and the ratio of the alkali solution to the second-stage vulcanized liquid is 1:

1.

2. The method for recovering nickel salts from copper sulfate production wastewater by a staged precipitation method according to claim 1, wherein: In step S1, the copper content in the copper sulfate production wastewater is 23-24 g / L, the arsenic content is 3-4 g / L, and the nickel content is 2-3 g / L. The content of the sulfiding agent added to the copper sulfate production wastewater is 12-13 g / L.

3. The method for recovering nickel salts from copper sulfate production wastewater by a staged precipitation method according to claim 2, wherein: The sulfiding agent is set to be one or more of sodium thiosulfate, sodium sulfide, sodium hydrosulfide and hydrogen sulfide.

4. The method for recovering nickel salts from copper sulfate production wastewater by a staged precipitation method according to claim 3, wherein: When filtering and washing the reaction liquid after the sulfidation reaction of the copper sulfate production wastewater, the mixed liquid after the sulfidation reaction is first passed through a filtering device for solid-liquid separation, and then the solid matter is washed 2-3 times with washing liquid. Solid-liquid separation is required for each washing. The washed liquid is obtained and mixed with the separated liquid to obtain a section of post-sulfidation liquid. The separated solid is a section of sulfided slag containing copper and arsenic. The section of sulfided slag is transferred to a smelting production system for smelting and copper recovery.

5. The method for recovering nickel salts from copper sulfate production wastewater by a staged precipitation method according to claim 4, characterized in that: The filtering and washing method of the sulfidation reaction liquid of the first-stage sulfidation liquid is the same as the filtering and washing method of the sulfidation reaction liquid of the copper sulfate production wastewater, and the obtained second-stage sulfidation slag is subjected to the arsenic recovery process.

6. The method for recovering nickel salts from copper sulfate production wastewater by a staged precipitation method according to claim 5, characterized in that: In step S3, the alkali solution is set to be one or more of sodium hydroxide, calcium hydroxide and potassium hydroxide.

7. The method for recovering nickel salts from copper sulfate production wastewater by a staged precipitation method according to claim 6, characterized in that: The filtering and washing method of the neutralized reaction liquid after the neutralization of the second-stage sulfidation liquid is also the same as the filtering and washing method of the sulfidation reaction liquid of the copper sulfate production wastewater. The obtained neutralization slag is the nickel raw material, and the obtained neutralized liquid enters the wastewater treatment process for wastewater treatment.

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