Method for removing COD, oil and heavy metals from cobalt-nickel raffinate jointly

Abstract

The present application belongs to the technical field of wastewater treatment of nickel-cobalt raffinate, and particularly relates to a method for jointly removing COD, oil and heavy metals in cobalt-nickel raffinate. The method provided by the present application for jointly removing COD, oil and heavy metals in cobalt-nickel raffinate comprises the steps of oil removal adsorption, oil removal resin recovery, alkali precipitation, heavy metal removal adsorption, heavy metal removal resin recovery and the like. The method collects multiple adsorption procedures in one process, and can not only reduce the content of organic matter in the raffinate, but also deeply remove heavy metals, thereby reducing environmental risks, achieving the dual benefits of economic value and environmental friendliness. Experimental verification shows that, after the method is used, the effluent COD can be reduced from 1370 mg / L to below 500 mg / L, the effluent oil can be reduced from 391.4 mg / L to below 10 mg / L, and the effluent cobalt-nickel can be stably maintained below 0.3 mg / L. The combined process proposed in the present application improves the recovery efficiency of cobalt-nickel precious metals.

Description

Technical Field

[0001] This invention belongs to the field of nickel-cobalt raffinate wastewater treatment technology, specifically relating to a method for the combined removal of COD, oil and heavy metals from cobalt-nickel raffinate. Background Technology

[0002] In the traditional hydrometallurgical process of cobalt and nickel, a large amount of extractant (mainly P204 and P507) and sulfonated kerosene (as a diluent) are used in the extraction stage to extract cobalt and nickel metal. After extraction, a raffinate containing a high concentration of organic matter is generated. At the same time, the raffinate still contains a certain concentration of cobalt and nickel metal, which has extremely high economic value. Therefore, it is necessary to recover the cobalt and nickel metal ions.

[0003] In existing technologies, common practices include: (1) Alkali method: adding liquid alkali or lime milk to convert cobalt and nickel ions into precipitates, followed by filtration to remove cobalt and nickel ions. Although this method is simple and easy to implement, the treated wastewater still contains 1.0 to 5.0 mg / L of nickel and cobalt, which is difficult to completely precipitate and recover; (2) Oxidative precipitation method: adding liquid alkali and oxidant at the same time to oxidize divalent nickel ions into trivalent nickel ions, which are easier to precipitate. However, due to the higher pH requirement, a large amount of magnesium ions will also precipitate while cobalt and nickel are precipitated, and this method cannot reduce Ni to a lower level. It is worth noting that the presence of organic matter (mainly COD and oil) in the raffinate will seriously affect the chemical precipitation effect of cobalt and nickel metal, resulting in poor precipitation treatment effect. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for the combined removal of COD, oil, and heavy metals from cobalt-nickel raffinate. This method not only reduces the organic matter content in the raffinate but also deeply removes heavy metals, ultimately reducing environmental risks and achieving the dual benefits of creating economic value and environmental friendliness. Specifically, this invention includes the following:

[0005] A method for combined removal of COD, oil and heavy metals from cobalt-nickel raffinate includes the following steps:

[0006] (1) Oil removal adsorption: The cobalt-nickel raffinate is passed through the oil removal resin at a rate of 3-8 BV / h to remove oil and adsorb oil, and the oil removal resin and the oil removal liquid are obtained.

[0007] (2) Recycling of oil-absorbing resin: After washing the oil-absorbing resin with H2O2, the washed oil-absorbing resin and high oil content waste liquid are obtained. The washed oil-absorbing resin is desorbed by steam stripping to complete desorption and regeneration, and the regenerated oil-absorbing resin is obtained. The regenerated oil-absorbing resin is returned to step (1) for reuse, and the high oil content waste liquid is treated for oil recovery.

[0008] (3) Alkaline precipitation: Add an alkaline solution to the deoiled liquid, adjust the pH to 8-9, carry out the precipitation reaction, and then perform solid-liquid separation to obtain the alkaline precipitated liquid and the solid containing nickel hydroxide / cobalt; the obtained solid containing nickel hydroxide / cobalt is slurried and returned to the extraction workshop for reuse.

[0009] (4) Resorption: The alkali-precipitated liquid is passed through the sorption resin at a rate of 3-8 BV / h to remove sorption and adsorption, and the resin and the adsorbed liquid are obtained. The adsorbed liquid is then sent to the pH adjustment tank to adjust the pH to neutral, and then discharged to the wastewater discharge outlet in compliance with the standards.

[0010] (5) Recycling of heavy metal resin: The resin adsorbed with cobalt and nickel is desorbed and regenerated in sequence with acidic solution and alkaline solution to obtain regenerated heavy metal resin and high-concentration cobalt and nickel solution. The regenerated heavy metal resin is returned to step (4) for reuse, and the high-concentration cobalt and nickel solution is returned to the front end for reuse.

[0011] Preferably, the degreasing resin in step (1) is HPX30 type resin (Haipu HPX30 type degreasing and adsorption resin).

[0012] Preferably, in step (2): the mass concentration of H2O2 is 0.5-2%, the H2O2 cleaning time is 100-150 min, and the steam stripping time is 100-150 min.

[0013] Preferably, the alkaline solution in step (3) is a sodium hydroxide solution with a concentration of 30-50 g / L.

[0014] Preferably, the deweighting resin in step (4) is D402 type resin (Sennat D402 type macroporous chelating ion exchange resin).

[0015] Preferably, the specific method of step (5) is as follows: first, use a sulfuric acid solution with a concentration of 300-360 g / L to elute the resin adsorbing cobalt and nickel for 60-100 min; then use a sodium hydroxide solution with a concentration of 50-120 g / L to regenerate the eluted resin for 60-100 min.

[0016] Preferably, the adsorbed liquid phase in step (4) is compared with the cobalt-nickel raffinate in step (1) in that: the COD content is reduced by more than 65%, the oil content is reduced by more than 98%, the Ni content is reduced by more than 99.7%, and the Co content is reduced by more than 99.9%.

[0017] The beneficial effects of this invention are:

[0018] This invention provides a method for the combined removal of COD, oil, and heavy metals from cobalt-nickel raffinate, comprising steps such as oil removal adsorption, oil removal resin recovery, alkali precipitation, heavy metal removal adsorption, and heavy metal removal resin recovery. This method integrates multiple adsorption processes into a single flow, not only reducing the organic matter content in the raffinate but also deeply removing heavy metals, ultimately reducing environmental risks and achieving the dual benefits of economic value creation and environmental friendliness. Experimental verification shows that after treatment using the method disclosed in this invention, the effluent COD can be reduced from 1370 mg / L to below 500 mg / L, the effluent oil content can be reduced from 391.4 mg / L to below 10 mg / L, and the effluent cobalt and nickel content can be stably maintained below 0.3 mg / L. The combined process proposed in this invention improves the recovery efficiency of cobalt and nickel, precious metals. Attached Figure Description

[0019] Figure 1 This is a process flow diagram of the method disclosed in this invention;

[0020] Figure 2 A schematic diagram of an apparatus for implementing the method disclosed in this invention. Detailed Implementation

[0021] The following is in conjunction with the appendix Figure 1-2 The present invention will be described in detail below with reference to specific embodiments. The embodiments shown below are not intended to limit the scope of the invention as described in the claims. Furthermore, the complete contents of the configurations shown in the embodiments below are not limited to those necessary for the solution of the invention as described in the claims.

[0022] Reference Appendix Figure 1A method for combined removal of COD, oil, and heavy metals from cobalt-nickel raffinate includes a combined process of removing COD and oil by oil-removing resin adsorption, primary precipitation of cobalt-nickel heavy metals by alkaline method, and deep removal of cobalt-nickel heavy metals by heavy metal removal resin adsorption. A certain volume of cobalt-nickel raffinate is passed through a chromatography column packed with oil-removing resin at a certain flow rate, and samples are taken every 1 hour to detect COD and oil content. A certain volume of the adsorbed oil-removing resin solution is placed in a beaker, and the beaker is placed on a magnetic stirrer with a speed set to 200-400 r / min. The pH of the solution is adjusted to approximately 8.5 with a sodium hydroxide solution with a concentration of 30-50 g / L, and the mixture is stirred and reacted for 30 minutes. The solution is then filtered through filter paper, and the cobalt-nickel content in the filtrate is detected. Simultaneously, a certain volume of the filtrate is passed through a chromatography column packed with heavy metal removal resin at a certain flow rate, and samples are taken every 1 hour to detect the cobalt-nickel content. When the degreasing resin reaches its adsorption saturation capacity, it is washed with a 1% H2O2 solution for 120 minutes, then steam-stripped for 120 minutes to complete desorption and regeneration. It is then reused for further adsorption of COD and oil. When the heavy removal resin reaches its adsorption saturation capacity, it is desorbed with a 300-360 g / L sulfuric acid solution for 60-100 minutes, then regenerated with a 50-120 g / L sodium hydroxide solution for 60-100 minutes. It is then reused for further deep removal of cobalt and nickel. Calculations based on experimental data show that, compared to the cobalt and nickel raffinate, the adsorbed liquid phase treated by this invention reduces COD content by more than 65%, oil content by more than 98%, Ni content by more than 99.7%, and Co content by more than 99.9%.

[0023] Preferably, the method for jointly removing COD, oil, and heavy metals from cobalt-nickel raffinate relies on a system for jointly removing COD, oil, and heavy metals from cobalt-nickel raffinate, the system of which is described in the attached reference document. Figure 2 The system includes an oil-removing resin ion exchange tank, a liquid alkali dosing reactor, a solid-liquid separation filter press, a heavy-duty resin ion exchange tank, and a pH adjustment tank, which are connected in sequence by pipelines. A first booster pump is installed on the pipeline between the oil-removing resin ion exchange tank and the liquid alkali dosing reactor, a second booster pump is installed on the pipeline between the liquid alkali dosing reactor and the solid-liquid separation filter press, a third booster pump is installed between the solid-liquid separation filter press and the heavy-duty resin ion exchange tank, and a fourth booster pump is installed between the heavy-duty resin ion exchange tank and the pH adjustment tank.

[0024] Example 1

[0025] A method for combined removal of COD, oil and heavy metals from cobalt-nickel raffinate. In this embodiment, the cobalt-nickel raffinate from the hydrometallurgical process contains the following components: COD 1370 mg / L, oil 73.8 mg / L, Co 68.7 mg / L, and Ni 368.8 mg / L.

[0026] 2000 ml of cobalt-nickel raffinate was passed through a chromatography column packed with degreasing resin (50 ml wet resin, flow rate 5 BV) at a certain flow rate. Samples were taken every 1 hour to determine COD and oil content. 1000 ml of the degreasing resin adsorption solution was placed in a beaker and stirred on a magnetic stirrer at 200 rpm. The pH of the solution was adjusted to 8.5 with a 30 g / L sodium hydroxide solution, and the reaction was allowed to proceed for 20 minutes. The solution was then filtered through filter paper, and the cobalt-nickel content of the filtrate was determined. Simultaneously, 800 ml of the filtrate was passed through a chromatography column packed with heavy metal removal resin (50 ml wet resin, flow rate 5 BV) at a certain flow rate. Samples were taken every 1 hour to determine the cobalt-nickel content. When the degreasing resin reached its adsorption saturation capacity, it was washed with 1% H₂O₂ solution for 120 minutes, followed by steam stripping for 120 minutes to complete desorption and regeneration. The resin was then reused for subsequent COD and oil adsorption. When the heavy removal resin reaches its adsorption saturation capacity, it is desorbed with a sulfuric acid solution of 300 g / L for 60 min, then regenerated with a sodium hydroxide solution of 80 g / L for 60 min, and then reused for further deep removal of cobalt and nickel.

[0027] Table 1. Sample analysis results from Example 1

[0028] Sample Name COD (mg / L) Oil content (mg / L) Co (mg / L) Ni (mg / L) Cobalt-nickel raffinate 1370 73.8 68.7 368.8 Oil-removing resin adsorption solution (after oil removal) 502.9 1.7 68.7 368.8 Alkali precipitation liquid 480.4 0.1 1.48 11.8 After adsorption by heavy removal resin, the liquid 475.8 0.1 0.20 0.16

[0029] According to the experimental results, after combined treatment with degreasing resin, alkaline solution precipitation, and heavy removal resin, the COD of the cobalt-nickel raffinate was 475.8 mg / L, the oil content was 0.1 mg / L, the Co content was 0.20 mg / L, and the Ni content was 0.16 mg / L.

[0030] Example 2

[0031] A method for combined removal of COD, oil and heavy metals from cobalt-nickel raffinate. In this embodiment, the cobalt-nickel raffinate from the hydrometallurgical process has the following characteristics: COD 1220 mg / L, oil 70.6 mg / L, Co 74.5 mg / L, and Ni 228.6 mg / L.

[0032] 2000 ml of cobalt-nickel raffinate was passed through a chromatography column packed with degreasing resin (50 ml wet resin, flow rate 5 BV) at a certain flow rate. Samples were taken every 1 hour to determine COD and oil content. 1000 ml of the degreasing resin adsorption solution was placed in a beaker and stirred on a magnetic stirrer at 300 rpm. The pH of the solution was adjusted to 8.5 with a 40 g / L sodium hydroxide solution, and the reaction was allowed to proceed for 20 minutes. The solution was then filtered through filter paper, and the cobalt-nickel content of the filtrate was determined. Simultaneously, 800 ml of the filtrate was passed through a chromatography column packed with heavy metal removal resin (50 ml wet resin, flow rate 5 BV) at a certain flow rate. Samples were taken every 1 hour to determine the cobalt-nickel content. When the resin reached its adsorption saturation capacity, the degreasing resin was washed with 1% H₂O₂ solution for 120 minutes, followed by steam stripping for 120 minutes to complete desorption and regeneration. The resin was then reused for subsequent COD and oil adsorption. When the heavy removal resin reaches its adsorption saturation capacity, it is desorbed with a sulfuric acid solution of 320 g / L for 80 min, then regenerated with a sodium hydroxide solution of 100 g / L for 80 min, and then reused for further deep removal of cobalt and nickel.

[0033] Table 2. Sample analysis results from Example 2

[0034] Sample Name COD (mg / L) Oil content (mg / L) Co (mg / L) Ni (mg / L) Cobalt-nickel raffinate 1220 70.6 74.5 228.6 Oil-removing resin adsorption solution (after oil removal) 447.4 0.1 74.5 228.6 Alkali precipitation liquid 425.8 0.1 2.2 21.9 After adsorption by heavy resin, the liquid 418.5 0.1 0.19 0.23

[0035] According to the experimental results, after combined treatment with degreasing resin, alkaline solution precipitation, and heavy removal resin, the COD of the cobalt-nickel raffinate was 418.5 mg / L, the oil content was 0.1 mg / L, the Co content was 0.19 mg / L, and the Ni content was 0.23 mg / L.

[0036] Example 3

[0037] A method for combined removal of COD, oil and heavy metals from cobalt-nickel raffinate. In this embodiment, the cobalt-nickel raffinate from the hydrometallurgical process has the following composition: COD 836.6 mg / L, oil 391.4 mg / L, Co 80.8 mg / L, and Ni 318.5 mg / L.

[0038] 2000 ml of cobalt-nickel raffinate was passed through a chromatography column packed with degreasing resin (50 ml wet resin, flow rate 5 BV) at a certain flow rate. Samples were taken every 1 hour to analyze COD and oil content. 1000 ml of the degreasing resin adsorption solution was placed in a beaker and stirred on a magnetic stirrer at 400 rpm. The pH of the solution was adjusted to 8.4 with a 50 g / L sodium hydroxide solution, and the reaction was allowed to proceed for 20 minutes. The solution was then filtered through filter paper, and the cobalt-nickel content of the filtrate was analyzed. Simultaneously, 800 ml of the filtrate was passed through a chromatography column packed with heavy metal removal resin (50 ml wet resin, flow rate 5 BV) at a certain flow rate. Samples were taken every 1 hour to analyze the cobalt-nickel content. When the resin reached its adsorption saturation capacity, the degreasing resin was washed with 1% H₂O₂ solution for 120 minutes, followed by steam stripping for 120 minutes to complete desorption and regeneration. The resin was then reused for subsequent COD and oil adsorption. When the heavy removal resin reaches its adsorption saturation capacity, it is desorbed with a sulfuric acid solution of 360 g / L for 100 min, then regenerated with a sodium hydroxide solution of 120 g / L for 100 min, and then reused for further deep removal of cobalt and nickel.

[0039] Table 3. Sample analysis results from Example 3

[0040] Sample Name COD (mg / L) Oil content (mg / L) Co (mg / L) Ni (mg / L) Cobalt-nickel raffinate 836.6 391.4 80.8 318.5 Oil-removing resin adsorption solution (after oil removal) 152.5 10.0 80.8 318.5 Alkali precipitation liquid 134.9 8.8 2.2 21.2 After adsorption by heavy resin, the liquid 120.2 6.5 0.19 0.23

[0041] According to the experimental results, after combined treatment with degreasing resin, alkaline solution precipitation, and heavy removal resin, the COD of the cobalt-nickel raffinate was 120.2 mg / L, the oil content was 6.5 mg / L, the Co content was 0.19 mg / L, and the Ni content was 0.23 mg / L.

[0042] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for combined removal of COD, oil, and heavy metals from cobalt-nickel raffinate, characterized in that, Includes the following steps: (1) Oil removal adsorption: The cobalt-nickel raffinate is passed through the oil removal resin at a rate of 3-8 BV / h to remove oil and adsorb oil, and the oil removal resin and the oil removal liquid are obtained. (2) Recycling of oil-absorbing resin: The oil-absorbing resin adsorbed with oil is washed with H2O2 with a mass concentration of 0.5-2% to obtain washed oil-absorbing resin and high oil content waste liquid. The washed oil-absorbing resin is desorbed by steam stripping to complete desorption and regeneration to obtain regenerated oil-absorbing resin. The regenerated oil-absorbing resin is returned to step (1) for reuse, and the high oil content waste liquid is treated for oil recovery. (3) Alkali precipitation: Add sodium hydroxide solution with a concentration of 30-50 g / L to the deoiled liquid, adjust the pH to 8-9, carry out precipitation reaction, and then perform solid-liquid separation to obtain the alkaline precipitated liquid and solid containing nickel / cobalt hydroxide. (4) Resorption: The alkaline precipitation solution is passed through the sorption resin at a rate of 3-8 BV / h to perform sorption adsorption, and the resin adsorbed with cobalt and nickel and the adsorbed solution are obtained. (5) Recycling of heavy-duty resin: The resin adsorbed with cobalt and nickel is desorbed and regenerated in sequence with acidic solution and alkaline solution to obtain regenerated heavy-duty resin and high-concentration cobalt and nickel solution. The regenerated heavy-duty resin is returned to step (4) for reuse.

2. The method for combined removal of COD, oil, and heavy metals from cobalt-nickel raffinate according to claim 1, characterized in that, The degreasing resin used in step (1) is HPX30 type resin.

3. The method for combined removal of COD, oil, and heavy metals from cobalt-nickel raffinate according to claim 1, characterized in that, Step (2): The cleaning time of H2O2 is 100-150 min; the steam stripping time is 100-150 min.

4. The method for combined removal of COD, oil, and heavy metals from cobalt-nickel raffinate according to claim 1, characterized in that, The de-weighting resin used in step (4) is D402 type resin.

5. The method for combined removal of COD, oil, and heavy metals from cobalt-nickel raffinate according to claim 1, characterized in that, The specific method of step (5) is as follows: First, use a sulfuric acid solution with a concentration of 300-360 g / L to elute the resin adsorbing cobalt and nickel for 60-100 min; then use a sodium hydroxide solution with a concentration of 50-120 g / L to regenerate the eluted resin for 60-100 min.

6. The method for combined removal of COD, oil, and heavy metals from cobalt-nickel raffinate according to any one of claims 1-5, characterized in that, The liquid phase after adsorption in step (4) is different from the cobalt-nickel raffinate in step (1): COD content is reduced by more than 65%, oil content by more than 98%, Ni content by more than 99.7%, and Co content by more than 99.9%.

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