Treatment method of nickel-cobalt-containing sulfate wastewater

Abstract

The invention discloses a treatment method of nickel-cobalt-containing sulfate wastewater, and relates to the technical field of wastewater treatment. A part of sulfate wastewater containing nickel and cobalt generated in the P507 cobalt extraction stage is used for diluting the rough cobalt sulfate solution from the leaching workshop, so that the consumption of pure water consumed by pulping in the leaching workshop is reduced, the pulping frequency of the leaching workshop can be reduced, and the labor cost is greatly reduced. In the HBL116 nickel extraction stage, the HBL116 extraction agent is used for further extracting the other part of sulfate wastewater containing nickel and cobalt generated in the P507 cobalt extraction stage, a low-impurity nickel-cobalt binary solution can be output, and the problems that a high-purity cobalt chloride / cobalt sulfate solution is high in production cost, high in environmental protection pressure and the like are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a method for treating nickel-cobalt sulfate wastewater. Background Art

[0002] Cobalt chloride is a precursor for preparing ternary positive electrode materials for lithium batteries, and is also the basic raw material for preparing battery-grade high-purity cobalt tetroxide. It is widely used in the field of new energy batteries. Currently, the most common method for preparing cobalt chloride solution is solvent extraction. Solvent extraction has the advantages of short process, high efficiency, and low energy consumption. It is considered to be the most promising method for deeply removing impurities such as calcium, copper, and manganese from cobalt sulfate solution. Commonly used extractants include P204, P507, etc. According to the extraction order of P204 and P507 metal ions, sulfuric acid is often used to leach cobalt hydroxide, P204 is used to remove impurities, and finally P507 is used to extract cobalt and then hydrochloric acid is used for back extraction to obtain a cobalt chloride solution with a higher main content.

[0003] However, the current solvent extraction method has several drawbacks: The extraction of cobalt with P507 during the preparation of cobalt chloride solution produces a large amount of sulfate wastewater containing nickel and cobalt. Conventional treatment involves direct disposal of this wastewater to the wastewater treatment system. This large volume of sulfate wastewater increases the consumption of treatment materials, leading to higher production costs. Furthermore, this sulfate wastewater has a high nickel and cobalt content, making it difficult to treat and increasing environmental pressure.

[0004] Therefore, in the production process of preparing cobalt chloride solution using crude cobalt sulfate, the treatment of wastewater containing nickel and cobalt sulfate is a major focus of reducing production costs. If the nickel and cobalt metals in this wastewater can be recovered and the wastewater generation can be reduced, it will not only increase the recovery rate of valuable metals, but also greatly reduce production costs and the pressure of back-end wastewater treatment, and promote the stable development of the new energy industry.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The object of the present invention is to provide a method for treating nickel-cobalt sulfate wastewater, aiming to reduce the amount of wastewater generated in the process and at the same time reduce the impurity content in the nickel-cobalt solution product.

[0007] The present invention is achieved in that:

[0008] In a first aspect, the present invention provides a method for treating nickel-cobalt sulfate wastewater, comprising:

[0009] Wastewater reuse stage: nickel-cobalt sulfate wastewater and crude cobalt sulfate solution are mixed to obtain cobalt sulfate dilution solution;

[0010] P204 impurity extraction stage: The cobalt sulfate dilution liquid is extracted and impurities are removed using the P204 extractant. Impurities enter the organic phase and are separated to obtain the first raffinate;

[0011] P507 cobalt extraction stage: The first raffinate is extracted with P507 extractant, and the second raffinate obtained after separation is sulfate wastewater containing nickel and cobalt. Part of the second raffinate is returned to the wastewater reuse stage, and the other part enters the HBL116 nickel extraction stage;

[0012] HBL116 nickel extraction stage: The second raffinate is extracted using HBL116 extractant to obtain a third raffinate and an organic phase containing nickel and cobalt after separation. The third raffinate is output as wastewater.

[0013] In an optional embodiment, when the magnesium content in the second raffinate is greater than or equal to 5 g / L, returning the wastewater to the wastewater reuse stage is stopped; when the magnesium content in the second raffinate is less than or equal to 4 g / L, part of the second raffinate continues to be returned to the wastewater reuse stage.

[0014] In an optional embodiment, the ratio of the volume of the second raffinate returned to the wastewater reuse stage to the volume entering the HBL116 nickel extraction stage is 1:(4-6).

[0015] In an optional embodiment, the amount of nickel-cobalt sulfate wastewater added is adjusted so that the cobalt content in the cobalt sulfate dilution solution is between 60 g / L and 65 g / L;

[0016] And / or, the cobalt content in the crude cobalt sulfate solution is 85 g / L-90 g / L.

[0017] In an optional embodiment, the P204 extraction stage comprises: mixing and saponifying the P204 extractant and the first diluent to obtain a first extraction reagent, and mixing the first extraction reagent with the cobalt sulfate diluent for extraction;

[0018] Preferably, the volume ratio of the P204 extractant to the first diluent is 1:(3.5-4.5);

[0019] Preferably, the volume ratio of the first extraction reagent to the cobalt sulfate dilution is 1:(1.0-1.1);

[0020] Preferably, the first diluent is sulphonated kerosene.

[0021] In an optional embodiment, the P507 cobalt extraction stage comprises: mixing and saponifying the P507 extractant and a second diluent to obtain a second extraction reagent, and mixing the second extraction reagent with the first raffinate for extraction;

[0022] Preferably, the volume ratio of the P507 extractant to the second diluent is 1:(2.5-3.5);

[0023] Preferably, the volume ratio of the second extraction reagent to the first raffinate is 1:(0.15-0.20);

[0024] Preferably, the second diluent is sulphonated kerosene.

[0025] In an optional embodiment, the HBL116 nickel extraction stage includes: mixing the HBL116 extractant and the third diluent and saponifying to obtain a third extraction reagent, mixing the third extraction reagent with the second raffinate for extraction, and separating to obtain the third raffinate and an organic phase containing nickel and cobalt.

[0026] In an optional embodiment, the volume ratio of the HBL116 extractant to the third diluent is 1:(3.5-4.5);

[0027] and / or, the volume ratio of the third extraction reagent to the second raffinate is 1:(1.8-2.2);

[0028] And / or, the third diluent is sulfonated kerosene.

[0029] In an optional embodiment, the nickel-cobalt-containing organic phase is washed and stripped to obtain a nickel-cobalt-containing binary solution;

[0030] And / or, the third raffinate is subjected to evaporation treatment.

[0031] In an optional embodiment, the back extraction is performed using a sulfuric acid solution with a concentration of 0.7 mol / L-0.8 mol / L.

[0032] The present invention has the following beneficial effects: by using a portion of the nickel-cobalt sulfate wastewater generated in the P507 cobalt extraction stage to dilute the crude cobalt sulfate solution from the leaching plant, the pure water consumption for pulping in the leaching plant is reduced, the frequency of pulping in the leaching plant is also reduced, and labor costs are greatly reduced. In the HBL116 nickel extraction stage, the HBL116 extractant is used to further extract the other portion of the nickel-cobalt sulfate wastewater generated in the P507 cobalt extraction stage, producing a low-impurity nickel-cobalt binary solution. This solves the pain points of high production costs and high environmental pressures for high-purity cobalt chloride / cobalt sulfate solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 This is a process flow chart for the treatment of nickel-cobalt sulfate wastewater. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0036] The present invention provides a method for treating nickel-cobalt sulfate wastewater, such as Figure 1 As shown, a portion of the nickel-cobalt sulfate wastewater generated in the P507 cobalt extraction stage is used to dilute the crude cobalt sulfate solution from the leaching workshop, and another portion of the nickel-cobalt sulfate wastewater generated in the P507 cobalt extraction stage is further extracted using the HBL116 extractant. This can significantly reduce the amount of wastewater generated in the process and effectively reduce production costs. At the same time, it can also output a high-purity nickel-cobalt solution product, thereby improving the recovery rate of nickel and cobalt.

[0037] The following is a description of each stage, as follows:

[0038] S1. Wastewater reuse stage

[0039] The nickel-cobalt sulfate wastewater generated in the P507 cobalt extraction stage is mixed with the crude cobalt sulfate solution from the leaching workshop to produce a dilute cobalt sulfate solution. In this embodiment of the present invention, the nickel-cobalt sulfate wastewater generated in the P507 cobalt extraction stage is used to dilute the crude cobalt sulfate solution produced in the leaching workshop. This reduces the wastewater pressure on the back-end workshop while ensuring product quality, reduces the water consumption of the leaching workshop, and significantly reduces production costs.

[0040] Specifically, the preparation of crude cobalt sulfate solution in a leaching workshop is an existing process, which uses sulfuric acid solution to leach the ore to obtain a crude cobalt sulfate solution with a high cobalt content. When the process provided by the embodiment of the present invention is first implemented, the crude cobalt sulfate solution can be diluted with water.

[0041] In some embodiments, the cobalt content in the crude cobalt sulfate solution before dilution is 85 g / L-90 g / L, such as 85 g / L, 86 g / L, 87 g / L, 88 g / L, 89 g / L, 90 g / L, etc. By adjusting the amount of nickel-cobalt sulfate wastewater added, the cobalt content in the cobalt sulfate dilution solution obtained after dilution is adjusted to be 60 g / L-65 g / L, such as 60 g / L, 61 g / L, 62 g / L, 63 g / L, 64 g / L, 65 g / L, etc. The cobalt concentration after dilution is preferably within the above range, which is conducive to improving the extraction effect and increasing the recovery rate of nickel and cobalt.

[0042] S2, P204 extraction stage

[0043] The cobalt sulfate dilution obtained in step S1 is extracted and impurities removed using a P204 extractant to remove impurities such as Ca and Mn from the cobalt sulfate dilution. During the extraction process, the impurities enter the organic phase. The first raffinate obtained after separation is the cobalt sulfate after impurities are removed. The first raffinate enters step S3.

[0044] In some embodiments, the steps of the P204 extraction stage include: mixing the P204 extractant and the first diluent to obtain an organic phase, saponifying the organic phase to obtain a first extraction reagent, mixing the first extraction reagent with the cobalt sulfate dilution obtained in step S1 for extraction, and the obtained first raffinate entering the P507 cobalt extraction stage.

[0045] In some embodiments, the first diluent may be sulfonated kerosene, specifically 260# sulfonated kerosene, but is not limited thereto. The volume ratio of the P204 extractant to the first diluent is 1:(3.5-4.5), such as 1:3.5, 1:3.8, 1:4.0, 1:4.2, 1:4.5, etc. The volume ratio of the first extraction reagent to the cobalt sulfate diluent is 1:(1.0-1.1), such as 1:1.00, 1:1.03, 1:1.05, 1:1.08, 1:1.10, etc. By adjusting the ratio of the P204 extractant to the first diluent and the dosage of the first extraction reagent, the extraction effect can be improved, and impurities such as Ca and Mn can be more fully removed.

[0046] Specifically, when preparing the first extraction reagent, the organic phase needs to be saponified with an alkaline substance. The main purpose of this step is to react the acidic extractant with the alkaline substance to enhance its metal binding capacity and selectivity. The alkaline substance used in the saponification process can be ammonia water, which is converted into an ammonium salt after the saponification reaction.

[0047] S3, P507 cobalt extraction stage

[0048] The first raffinate is extracted using a P507 extractant, allowing most of the cobalt to enter the organic phase. The extracted organic phase and the second raffinate (also called cobalt-extracted raffinate) obtained after separation contain high-purity cobalt, which is output as a product for the preparation of cobalt chloride; the second raffinate is a sulfate wastewater containing nickel and cobalt, and the sulfate wastewater containing nickel and cobalt contains a small amount of cobalt. In this embodiment of the present invention, part of the second raffinate is returned to the wastewater reuse stage (i.e., step S1), and the other part enters the HBL116 nickel extraction stage (i.e., step S4). In this embodiment of the present invention, after the cobalt-extracted raffinate is reused in the leaching workshop, the Ni and Co content of the cobalt-extracted raffinate is enriched, which facilitates the operation of the HBL116 nickel extraction process and has the characteristics of being easy to control.

[0049] In some embodiments, when the magnesium content in the second raffinate is greater than or equal to 5 g / L, the impurity content is high, and the return to the wastewater reuse stage is stopped, and the nickel extraction process in HBL 116 is entered. When the magnesium content in the second raffinate is less than or equal to 4 g / L, the normal reuse process is resumed, and a portion of the second raffinate is continued to be returned to the wastewater reuse stage.

[0050] Furthermore, when the magnesium content in the second raffinate is less than or equal to 4 g / L, the wastewater reuse conditions are met, and a portion of the second raffinate is returned to the wastewater reuse stage, while the other portion enters the HBL116 nickel extraction stage. Simultaneously, the ratio of the volume of the second raffinate returned to the wastewater reuse stage to the volume entering the HBL116 nickel extraction stage is controlled to be 1:(4-6), such as 1:4.0, 1:4.3, 1:4.5, 1:4.8, 1:5.0, 1:5.3, 1:5.5, 1:5.8, 1:6.0, etc. By adjusting the ratio of the second raffinate entering the two different stages, this portion of nickel and cobalt-containing sulfate wastewater can be more fully utilized, and the amount of process wastewater generated can be significantly reduced.

[0051] In some embodiments, the P507 cobalt extraction stage includes: mixing a P507 extractant and a second diluent to obtain an organic phase, saponifying the organic phase to obtain a second extraction reagent, and then mixing the second extraction reagent with the first raffinate for extraction. The second diluent can be sulfonated kerosene, specifically, but not limited to, 260# sulfonated kerosene. The volume ratio of the P507 extractant to the second diluent is 1:(2.5-3.5), such as 1:2.5, 1:2.8, 1:3.0, 1:3.2, 1:3.5, etc. The volume ratio of the second extraction reagent to the first raffinate is 1:(0.15-0.20), such as 1:0.15, 1:0.16, 1:0.17, 1:0.18, 1:0.19, 1:0.20, etc. By adjusting the ratio of the P507 extractant to the second diluent and the amount of the second extraction reagent, the extraction efficiency can be improved, allowing the cobalt to be more fully extracted into the organic phase.

[0052] Specifically, the organic phase needs to be saponified to prepare the second extraction reagent. The main purpose and reagents used in this step are similar to those in step S2 and are not repeated here. Testing has shown that the second raffinate output from the P507 cobalt extraction stage primarily contains nickel and cobalt, with a nickel content of approximately 0.9-1.5 g / L (e.g., 1.1 g / L) and a cobalt content of approximately 0.10-0.15 g / L (e.g., 0.12 g / L).

[0053] S4, HBL116 nickel extraction stage

[0054] A portion of the second raffinate obtained in step S3 is extracted using HBL116 extractant to allow nickel to enter the organic phase. After separation, a third raffinate and an organic phase containing nickel and cobalt are obtained. The third raffinate is output as wastewater, and the organic phase containing nickel and cobalt is stripped to obtain a high-purity nickel-cobalt binary liquid.

[0055] In some embodiments, the HBL116 nickel extraction stage includes the following steps: mixing the HBL116 extractant and a third diluent to obtain an organic phase, saponifying the organic phase to obtain a third extraction reagent, then mixing the third extraction reagent with the second raffinate for extraction, and separating to obtain the third raffinate and an organic phase containing nickel and cobalt. The third diluent can be sulfonated kerosene, specifically 260# sulfonated kerosene, but is not limited thereto. The volume ratio of the HBL116 extractant to the third diluent is 1:(3.5-4.5), such as 1:3.5, 1:3.8, 1:4.0, 1:4.2, 1:4.5, etc. The volume ratio of the third extraction reagent to the second raffinate is 1:(1.8-2.2), such as 1:1.8, 1:1.9, 1:2.0, 1:2.1, 1:2.2, etc. By adjusting the ratio of HBL116 extractant and the third diluent and the amount of the third extraction reagent, the extraction effect can be improved and nickel can be more fully extracted into the organic phase.

[0056] Specifically, the organic phase needs to be saponified when preparing the third extraction reagent. The main purpose of this step and the reagents used refer to step S2 and will not be repeated here.

[0057] Furthermore, the third raffinate can be sent to the water treatment workshop for further water treatment by evaporation. The amount of wastewater generated in the nickel extraction process of HBL116 is significantly reduced to 31.5m 3 / gold ton of cobalt. Specifically, gold ton of cobalt is a ton of metal cobalt, representing the weight of cobalt metal is 1 ton. For example, the cobalt concentration in the cobalt chloride solution produced by the P507 cobalt extraction process in this process is about 143g / L, so one ton of cobalt metal corresponds to about 7m 3 Cobalt chloride solution, i.e. production of 7m 3 Cobalt chloride solution will produce 31.5m 3 Wastewater.

[0058] Further, the organic phase containing nickel and cobalt is washed and stripped, so that the metal ions loaded in the organic phase are transferred back to the aqueous phase to obtain a binary liquid containing nickel and cobalt. Specifically, 0.125mol / L-0.175mol / L sulfuric acid solution can be used for washing to wash the Mg in the organic phase into the aqueous phase to avoid excessive Mg impurities in the nickel and cobalt sulfate binary liquid. Sulfuric acid solution can be used for stripping, and the concentration of the sulfuric acid solution can be 0.7mol / L-0.8mol / L, such as 0.70mol / L, 0.73mol / L, 0.75mol / L, 0.78mol / L, 0.80mol / L, etc. The concentration range of the sulfuric acid solution is conducive to fully stripping the nickel and cobalt elements within this range, thereby improving the recovery rate of nickel and cobalt.

[0059] It should be noted that the process provided by the embodiments of the present invention has the advantages of simple operation, high production efficiency, and a short process flow. Compared with other methods for treating the cobalt extraction residual solution (produced in the P507 cobalt extraction stage), it can effectively reduce production costs. The entire process provided by the embodiments of the present invention is carried out under normal pressure and does not require temperature control, which is conducive to industrial production.

[0060] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0061] It should be noted that the crude cobalt sulfate solution treated in the following examples and comparative examples comes from a leaching workshop and is obtained by mixed leaching using a 98% by mass concentrated sulfuric acid solution and cobalt hydroxide powder. The composition of the crude cobalt sulfate solution is shown in Table 1.

[0062] Example 1

[0063] This embodiment provides a method for treating nickel-cobalt sulfate wastewater, which comprises the following steps:

[0064] (1) Wastewater Reuse Stage: Nickel-cobalt sulfate wastewater (cobalt extraction raffinate from step (3)) is mixed with crude cobalt sulfate solution, and the Co concentration in the cobalt sulfate dilution solution sent to the extraction workshop is controlled to be 60 g / L. Reuse is temporarily stopped when the Mg content in the cobalt extraction raffinate obtained in step (3) is ≥5 g / L, and is resumed when the Mg content is ≤4 g / L.

[0065] (2) P204 extraction stage: P204 extractant and 260# sulfonated kerosene are mixed in a volume ratio of 1:4 to obtain an organic phase. The organic phase is mixed with a 20% by mass ammonia solution and saponified. The saponification rate is controlled at 40%. After saponification, a first extraction reagent is obtained. The first extraction reagent and the cobalt sulfate dilution obtained in step (1) are mixed in a volume ratio of 1:1 to extract. The resulting raffinate enters the P507 cobalt extraction stage.

[0066] (3) P507 cobalt extraction stage: P507 extractant and 260# sulfonated kerosene are mixed in a volume ratio of 1:3 to obtain an organic phase. The organic phase is mixed with a 20% ammonia solution by mass for saponification. The saponification rate is controlled at 55%. After saponification, a second extraction reagent is obtained. The second extraction reagent is mixed with the raffinate obtained in step (2) from which Ca and Mn have been removed in a volume ratio of 1:0.15 to carry out an extraction reaction. The separated cobalt extraction raffinate is a sulfate wastewater containing nickel and cobalt. Part of this wastewater is sent to the subsequent HBL116 nickel extraction process, and part is returned to step (1). The volume ratio of the cobalt extraction raffinate sent to processes (1) and (4) is 1:4.

[0067] (4) HBL116 nickel extraction stage: HBL116 extractant and 260# sulfonated kerosene are mixed in a volume ratio of 1:4 to obtain an organic phase, which is mixed with a 20% ammonia solution for saponification, and the saponification rate is controlled at 50%. After saponification, a third extraction reagent is obtained. The third extraction reagent and the nickel-cobalt-containing sulfate wastewater obtained in step (3) are mixed in a volume ratio of 1:1.8 to perform an extraction reaction to recover nickel and cobalt metals. After the nickel and cobalt are extracted from the organic phase, it is washed with a 0.15 mol / L sulfuric acid solution. Then, in the stripping section, a sulfuric acid solution with a hydrogen ion concentration of 1.5 mol / L (i.e., the concentration of the sulfuric acid solution is 0.75 mol / L) is used to strip the loaded organic phase to obtain a nickel-cobalt sulfate binary solution (the volume ratio of the organic phase to the stripping acid is controlled to be 15:1, the same below). The obtained raffinate is sent to the water treatment workshop for evaporation treatment.

[0068] After testing, the nickel and cobalt in the nickel-cobalt wastewater obtained in step (3) of this embodiment are 1.31 g / L and 0.15 g / L respectively. The nickel-cobalt sulfate binary solution prepared in step (4) of this embodiment has a Co concentration of 2.17 g / L, a Ni concentration of 42.69 g / L, and a Mg concentration of 0.015 g / L. The raffinate wastewater produced in step (4) is 34.31 m 3 / gold ton of cobalt, of which the cobalt and nickel contents are 3.94mg / L and 2.81mg / L respectively.

[0069] Example 2

[0070] This embodiment provides a method for treating nickel-cobalt sulfate wastewater, which comprises the following steps:

[0071] (1) Wastewater Reuse Stage: Nickel-cobalt sulfate wastewater (cobalt extraction raffinate from step (3)) is mixed with crude cobalt sulfate solution, and the Co concentration in the cobalt sulfate dilution solution sent to the extraction workshop is controlled to be 60 g / L. Reuse is temporarily stopped when the Mg content in the cobalt extraction raffinate obtained in step (3) is ≥5 g / L, and is resumed when the Mg content is ≤4 g / L.

[0072] (2) P204 extraction stage: P204 extractant and 260# sulfonated kerosene are mixed in a volume ratio of 1:4 to obtain an organic phase. The organic phase is mixed with a 20% by mass ammonia solution and saponified. The saponification rate is controlled at 40%. After saponification, a first extraction reagent is obtained. The first extraction reagent is mixed with the cobalt sulfate dilution obtained in step (1) in a volume ratio of 1:1 for extraction. The resulting raffinate enters the P507 cobalt extraction stage.

[0073] (3) P507 cobalt extraction stage: P507 extractant and 260# sulfonated kerosene are mixed in a volume ratio of 1:3 to obtain an organic phase. The organic phase is mixed with a 20% ammonia solution by mass and saponified. The saponification rate is controlled at 55%. After saponification, a second extraction reagent is obtained. The second extraction reagent is mixed with the raffinate obtained in step (2) from which Ca and Mn have been removed in a volume ratio of 1:0.15 to carry out an extraction reaction. The separated cobalt extraction raffinate is a sulfate wastewater containing nickel and cobalt. Part of this wastewater is sent to the subsequent HBL116 nickel extraction process, and part is returned to step (1). The volume ratio of the cobalt extraction raffinate sent to processes (1) and (4) is 1:5.

[0074] (4) HBL116 nickel extraction stage: HBL116 extractant and 260# sulfonated kerosene are mixed in a volume ratio of 1:4 to obtain an organic phase, and the organic phase is mixed with a 20% ammonia solution for saponification, and the saponification rate is controlled at 50%. After saponification, a third extraction reagent is obtained. The third extraction reagent and the nickel-cobalt-containing sulfate wastewater obtained in step (3) are mixed in a volume ratio of 1:1.8 to perform an extraction reaction to recover nickel and cobalt metals. After the nickel and cobalt are extracted from the organic phase, it is washed with a 0.15 mol / L sulfuric acid solution, and then the loaded organic phase is stripped with a sulfuric acid solution with a hydrogen ion concentration of 1.5 mol / L (i.e., the concentration of the sulfuric acid solution is 0.75 mol / L) in the stripping section to obtain a nickel-cobalt sulfate binary liquid, and the resulting raffinate is sent to a water treatment workshop for evaporation.

[0075] After testing, the nickel and cobalt in the nickel-cobalt wastewater obtained in step (3) of this embodiment are 1.21 g / L and 0.11 g / L respectively. The nickel-cobalt sulfate binary solution prepared in step (4) of this embodiment contains 1.14 g / L of Co, 43.85 g / L of Ni, and 0.002 g / L of Mg. The raffinate wastewater produced in step (4) is 31.10 m 3 / gold ton of cobalt, of which the cobalt and nickel contents are 2.57mg / L and 2.21mg / L respectively.

[0076] Example 3

[0077] This embodiment provides a method for treating nickel-cobalt sulfate wastewater, which comprises the following steps:

[0078] (1) Wastewater Reuse Stage: Nickel-cobalt sulfate wastewater (cobalt extraction raffinate from step (3)) is mixed with crude cobalt sulfate solution, and the Co concentration in the cobalt sulfate dilution solution sent to the extraction workshop is controlled to be 60 g / L. Reuse is temporarily stopped when the Mg content in the cobalt extraction raffinate obtained in step (3) is ≥5 g / L, and is resumed when the Mg content is ≤4 g / L.

[0079] (2) P204 extraction stage: P204 extractant and 260# sulfonated kerosene are mixed in a volume ratio of 1:4 to obtain an organic phase. The organic phase is mixed with a 20% by mass ammonia solution and saponified. The saponification rate is controlled at 40%. After saponification, a first extraction reagent is obtained. The first extraction reagent and the cobalt sulfate dilution obtained in step (1) are mixed in a volume ratio of 1:1 to extract. The resulting raffinate enters the P507 cobalt extraction stage.

[0080] (3) P507 cobalt extraction stage: P507 extractant and 260# sulfonated kerosene are mixed in a volume ratio of 1:3 to obtain an organic phase. The organic phase is mixed with a 20% ammonia solution by mass and saponified. The saponification rate is controlled at 55%. After saponification, a second extraction reagent is obtained. The second extraction reagent is mixed with the raffinate obtained in step (2) from which Ca and Mn have been removed in a volume ratio of 1:0.15 to carry out an extraction reaction. The separated cobalt extraction raffinate is a sulfate wastewater containing nickel and cobalt. Part of this wastewater is sent to the subsequent HBL116 nickel extraction process, and part is returned to step (1). The volume ratio of the cobalt extraction raffinate sent to processes (1) and (4) is 1:6.

[0081] (4) HBL116 nickel extraction stage: HBL116 extractant and 260# sulfonated kerosene are mixed in a volume ratio of 1:4 to obtain an organic phase, and the organic phase is mixed with a 20% ammonia solution for saponification, and the saponification rate is controlled at 50%. After saponification, a third extraction reagent is obtained. The third extraction reagent and the nickel-cobalt-containing sulfate wastewater obtained in step (3) are mixed in a volume ratio of 1:1.8 to perform an extraction reaction to recover nickel and cobalt metals. After the nickel and cobalt are extracted from the organic phase, it is washed with a 0.15 mol / L sulfuric acid solution, and then the loaded organic phase is stripped with a sulfuric acid solution with a hydrogen ion concentration of 1.5 mol / L (i.e., the concentration of the sulfuric acid solution is 0.75 mol / L) in the stripping section to obtain a nickel-cobalt sulfate binary liquid, and the resulting raffinate is sent to a water treatment workshop for evaporation.

[0082] After testing, the nickel and cobalt in the nickel-cobalt wastewater obtained in step (3) of this embodiment are 1.38 g / L and 0.16 g / L respectively. The nickel-cobalt sulfate binary solution prepared in step (4) of this embodiment has a Co concentration of 2.14 g / L, a Ni concentration of 41.59 g / L, and a Mg concentration of 0.004 g / L. The raffinate wastewater produced in step (4) is 34.85 m 3 / gold ton of cobalt, of which the cobalt and nickel contents are 3.11mg / L and 3.27mg / L respectively.

[0083] Example 4

[0084] The only difference from Example 1 is that in step (3), the volume ratio of the cobalt extraction residual solution going to steps (1) and (4) is 1:3.

[0085] After testing, the nickel and cobalt in the nickel-cobalt wastewater obtained in step (3) of this embodiment are 1.36 g / L and 0.15 g / L respectively. The nickel-cobalt sulfate binary solution prepared in step (4) of this embodiment has a Co concentration of 2.23 g / L, a Ni concentration of 42.14 g / L, and a Mg concentration of 0.009 g / L. The raffinate wastewater produced in step (4) is 33.55 m 3 / gold ton of cobalt, of which the cobalt and nickel contents are 3.55mg / L and 3.74mg / L respectively.

[0086] Example 5

[0087] The only difference from Example 1 is that in step (3), the volume ratio of the cobalt extraction residual solution going to processes (1) and (4) is 1:7.

[0088] After testing, the nickel and cobalt in the nickel-cobalt wastewater obtained in step (3) of this embodiment are 1.27 g / L and 0.13 g / L respectively. The nickel-cobalt sulfate binary solution prepared in step (4) of this embodiment has a Co concentration of 2.19 g / L, a Ni concentration of 41.58 g / L, and a Mg concentration of 0.007 g / L. The raffinate wastewater produced in step (4) is 36.12 m 3 / gold ton of cobalt, of which the cobalt and nickel contents are 3.45mg / L and 3.18mg / L respectively.

[0089] Example 6

[0090] The only difference from Example 1 is that the amount of extractant used and the ratio of the extractant to the pre-extraction solution in steps (2) to (4) are different. Specifically, in step (2), the P204 extractant is mixed with 260# sulfonated kerosene at a volume ratio of 1:3.5, and the volume ratio of the first extractant to the cobalt sulfate dilution is 1:1.1; in step (3), the P507 extractant is mixed with 260# sulfonated kerosene at a volume ratio of 1:2.5, and the second extractant is mixed with the raffinate obtained in step (2) from which Ca and Mn have been removed at a volume ratio of 1:0.20; in step (4), the HBL116 extractant is mixed with 260# sulfonated kerosene at a volume ratio of 1:3.5, and the third extractant is mixed with the nickel-cobalt sulfate wastewater obtained in step (3) at a volume ratio of 1:2.2.

[0091] After testing, the amount of raffinate wastewater produced in step (4) is 33.75m 3 / gold ton of cobalt, of which the cobalt and nickel contents were 4.23 mg / L and 3.59 mg / L respectively. Compared with Example 1, Example 6 increases the proportion of the extractant in the organic phase, thereby improving the organic phase's ability to extract the target metal. Simultaneously, the flow rate of the pre-extraction liquid is increased, thereby increasing the proportion of the target metal in the organic phase and resulting in a decrease in the amount of wastewater compared to Example 1.

[0092] Example 7

[0093] The only difference from Example 1 is that the amount of extractant used and the ratio of the extractant to the pre-extraction solution in steps (2) to (4) are different. Specifically, in step (2), the P204 extractant is mixed with 260# sulfonated kerosene at a volume ratio of 1:4.5, and the volume ratio of the first extractant to the cobalt sulfate dilution is 1:1.1; in step (3), the P507 extractant is mixed with 260# sulfonated kerosene at a volume ratio of 1:3.5, and the second extractant is mixed with the raffinate obtained in step (2) from which Ca and Mn have been removed at a volume ratio of 1:0.2; in step (4), the HBL116 extractant is mixed with 260# sulfonated kerosene at a volume ratio of 1:4.5, and the third extractant is mixed with the nickel-cobalt sulfate wastewater obtained in step (3) at a volume ratio of 1:2.2.

[0094] After testing, the amount of raffinate wastewater produced in step (4) is 34.51m 3 / gold ton of cobalt, of which the cobalt and nickel contents were 3.65 mg / L and 3.21 mg / L respectively. Compared with Example 1, Example 7 reduced the proportion of the extractant in the organic phase, resulting in a decrease in the ability of the organic phase to extract the target metal compared to Example 1. At the same time, the flow rate of the pre-extraction liquid was increased, resulting in an increase in the amount of wastewater compared to Example 1.

[0095] Comparative Example 1

[0096] This comparative example provides a method for treating nickel-cobalt sulfate wastewater. The main difference from Example 3 is that the extractant is replaced in step (4). The steps are as follows:

[0097] (1) Wastewater Reuse Stage: Nickel-cobalt sulfate wastewater (cobalt extraction residual solution from step (3)) is mixed with crude cobalt sulfate solution. The Co concentration in the cobalt sulfate dilution solution sent to the extraction workshop is controlled to be 60 g / L. The crude cobalt sulfate solution and nickel-cobalt wastewater are mixed in a volume ratio of 3.3:1. Reuse is temporarily stopped when the Mg content in the cobalt extraction residual solution obtained in step (3) is ≥5 g / L. Reuse is resumed when the Mg content is ≤4 g / L.

[0098] (2) P204 extraction stage: P204 extractant and 260# sulfonated kerosene are mixed in a volume ratio of 1:4 to obtain an organic phase. The organic phase is mixed with a 20% by mass ammonia solution and saponified. The saponification rate is controlled at 40%. After saponification, a first extraction reagent is obtained. The first extraction reagent and the cobalt sulfate dilution obtained in step (1) are mixed in a volume ratio of 1:1 to extract. The resulting raffinate enters the P507 cobalt extraction stage.

[0099] (3) P507 cobalt extraction stage: P507 extractant and 260# sulfonated kerosene are mixed in a volume ratio of 1:3 to obtain an organic phase. The organic phase is mixed with a 20% ammonia solution for saponification, and the saponification rate is controlled at 55%. After saponification, a second extraction reagent is obtained. The second extraction reagent is mixed with the raffinate obtained in step (2) from which Ca and Mn have been removed in a volume ratio of 1:0.15 to carry out an extraction reaction. The separated cobalt extraction raffinate is a sulfate wastewater containing nickel and cobalt. Part of this wastewater is sent to the subsequent P204 nickel and cobalt extraction stage, and part is returned to step (1). The volume ratio of the cobalt extraction raffinate sent to steps (1) and (4) is 1:6.

[0100] (4) P204 nickel and cobalt extraction stage: P204 extractant and 260# sulfonated kerosene are mixed in a volume ratio of 1:4 to obtain an organic phase, and the organic phase is mixed with a 20% ammonia solution for saponification, and the saponification rate is controlled at 50%. After saponification, a third extraction reagent is obtained. The third extraction reagent and the nickel and cobalt-containing sulfate wastewater obtained in step (3) are mixed in a volume ratio of 1:1.8 to perform an extraction reaction to recover nickel and cobalt metals. After the organic phase extracts nickel and cobalt, it is washed with a 0.25 mol / L sulfuric acid solution, and then in the stripping section, a sulfuric acid solution with a hydrogen ion concentration of 1.5 mol / L (i.e., the concentration of the sulfuric acid solution is 0.75 mol / L) is used to strip the loaded organic phase to obtain a nickel and cobalt sulfate binary liquid, and the obtained raffinate is sent to a water treatment workshop for evaporation.

[0101] After testing, the nickel and cobalt in the nickel-cobalt wastewater obtained in step (3) of this comparative example were 1.27 g / L and 0.18 g / L respectively. The nickel-cobalt sulfate binary solution prepared in step (4) of this embodiment had a Co concentration of 2.06 g / L, a Ni concentration of 37.56 g / L, and a Mg concentration of 0.127 g / L. The raffinate wastewater generated by the P204 nickel-cobalt extraction line was 38.67 m 3 / gold ton of cobalt, the nickel and cobalt contents in the raffinate are 15.29mg / L and 14.36mg / L respectively.

[0102] It should be noted that the pH of the P507 cobalt extraction residual solution in this comparative example is about 4.0. Under this condition, the extraction rates of Ni, Co, and Mg are similar. The Mg metal in the organic phase of the extraction section will increase significantly compared to the HBL116 extractant. In the washing section, a large amount of dilute sulfuric acid is needed to wash and remove the Mg metal. The amount of water in the residual solution is the amount of water before extraction + the amount of acid washing water. This results in a significant increase in the amount of wastewater of the P204 extractant compared to the HBL116 extractant under single variable conditions. At the same time, because the extraction rates of Ni, Co, and Mg are similar under the P204 extractant condition, their stripping rates are also similar, which means that the removal of Mg in the washing section cannot reach the effect of HBL116, and it is impossible to ensure that the Mg content in the nickel cobalt sulfate stripping solution is at a low level, and it is also impossible to ensure that the Ni and Co content in the wastewater are at a low level.

[0103] Table 1 Metal contents in crude cobalt sulfate solution before dilution

[0104] Co(g / L) Ni(g / L) Ca (g / L) Mn (g / L) Mg(g / L) Example 1 90.81 3.63 0.598 4.37 9.78 Example 2 89.57 3.53 0.614 4.12 9.16 Example 3 86.15 3.77 0.601 3.98 8.97

[0105] From the comparison of Examples 1-3, it can be seen that when the cobalt extraction residual solution obtained in step (3) is returned to step (1) at a ratio of 1:5 (i.e., Example 2), the amount of ammonium magnesium sulfate wastewater produced per ton of cobalt produced is less than that at 1:4 (Example 1) and 1:6 (Example 3), and the magnesium metal content in the produced nickel cobalt sulfate solution is lower.

[0106] By comparing Example 3 with Comparative Example 1, it can be seen that the extraction rates of magnesium and nickel-cobalt by the P204 extractant are similar. If the P204 extractant is used to treat the cobalt extraction residual solution, the amount of wastewater produced per ton of cobalt will increase significantly, and the magnesium impurity in the nickel-cobalt sulfate binary solution will be relatively high.

[0107] As can be seen, the use of HBL116 extractant in the embodiments of the present invention can complete the treatment of the nickel-cobalt sulfate wastewater generated in the P507 cobalt extraction process. If the entire cobalt extraction residual liquid were to enter the HBL116 nickel extraction process, not only would the wastewater volume be large, but it would also increase the pressure on the wastewater treatment system, increase auxiliary material consumption, and increase production costs such as labor costs. The present invention can efficiently recover the nickel and cobalt metals in the nickel-cobalt sulfate wastewater generated in the P507 cobalt extraction process by reusing it, ultimately obtaining a high-purity nickel-cobalt sulfate binary solution.

[0108] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for treating nickel-cobalt sulfate wastewater, characterized in that: include: Wastewater reuse stage: nickel-cobalt sulfate wastewater and crude cobalt sulfate solution are mixed to obtain cobalt sulfate dilution solution; P204 impurity extraction stage: using P204 extractant to extract and remove impurities from the cobalt sulfate dilution solution, and the impurities enter the organic phase, and after separation, a first raffinate is obtained; P507 cobalt extraction stage: The first raffinate is extracted with P507 extractant to obtain a second raffinate after separation, which is sulfate wastewater containing nickel and cobalt. Part of the second raffinate is returned to the wastewater reuse stage, and the other part enters the HBL116 nickel extraction stage; HBL116 nickel extraction stage: The second raffinate is extracted with HBL116 extractant to obtain a third raffinate and an organic phase containing nickel and cobalt after separation. The third raffinate is output as wastewater.

2. The method for treating nickel-cobalt sulfate wastewater according to claim 1, wherein: When the magnesium content in the second raffinate is greater than or equal to 5 g / L, returning the wastewater to the wastewater reuse stage is stopped; when the magnesium content in the second raffinate is less than or equal to 4 g / L, part of the second raffinate continues to be returned to the wastewater reuse stage.

3. The method for treating nickel-cobalt sulfate wastewater according to claim 1 or 2, characterized in that: The ratio of the volume of the second raffinate returned to the wastewater reuse stage to the volume entering the HBL116 nickel extraction stage is 1:(4-6).

4. The method for treating nickel-cobalt sulfate wastewater according to claim 1, wherein: By adjusting the amount of the nickel-cobalt sulfate wastewater added, the cobalt content in the cobalt sulfate dilution solution is adjusted to be between 60 g / L and 65 g / L; And / or, the cobalt content in the crude cobalt sulfate solution is 85 g / L-90 g / L.

5. The method for treating nickel-cobalt sulfate wastewater according to claim 1, wherein: The P204 extraction stage includes: mixing and saponifying a P204 extractant and a first diluent to obtain a first extraction reagent, and mixing the first extraction reagent with the cobalt sulfate diluent for extraction; Preferably, the volume ratio of the P204 extractant to the first diluent is 1:(3.5-4.5); Preferably, the volume ratio of the first extraction reagent to the cobalt sulfate dilution is 1:(1.0-1.1); Preferably, the first diluent is sulphonated kerosene.

6. The method for treating nickel-cobalt sulfate wastewater according to claim 1, wherein: The P507 cobalt extraction stage comprises: mixing and saponifying the P507 extractant and the second diluent to obtain a second extraction reagent, and mixing the second extraction reagent with the first raffinate for extraction; Preferably, the volume ratio of the P507 extractant to the second diluent is 1:(2.5-3.5); Preferably, the volume ratio of the second extraction reagent to the first raffinate is 1:(0.15-0.20); Preferably, the second diluent is sulphonated kerosene.

7. The method for treating nickel-cobalt sulfate wastewater according to claim 1, wherein: The HBL116 nickel extraction stage includes: mixing the HBL116 extractant and the third diluent and saponifying to obtain a third extraction reagent, mixing the third extraction reagent with the second raffinate for extraction, and separating to obtain the third raffinate and an organic phase containing nickel and cobalt.

8. The method for treating nickel-cobalt sulfate wastewater according to claim 7, characterized in that: The volume ratio of the HBL116 extractant to the third diluent is 1:(3.5-4.5); and / or, the volume ratio of the third extraction reagent to the second raffinate is 1:(1.8-2.2); And / or, the third diluent is sulfonated kerosene.

9. The method for treating nickel-cobalt sulfate wastewater according to claim 7, characterized in that: Washing and stripping the nickel-cobalt-containing organic phase to obtain a nickel-cobalt-containing binary liquid; And / or, the third raffinate is subjected to evaporation treatment.

10. The method for treating nickel-cobalt sulfate wastewater according to claim 9, characterized in that: Back extraction is performed using a sulfuric acid solution with a concentration of 0.7 mol / L-0.8 mol / L.

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