Method for removing chromium impurities from a nickel chloride solution and use thereof

Abstract

The application provides a method for removing chromium impurities from a nickel chloride solution and application thereof, and comprises the following steps: S1, adding hydrochloric acid into the nickel chloride solution to adjust the pH to 1.0-3.0; S2, adding FeCl3 into the system obtained in the step S1, adjusting the pH of the system to 3.5-4.5 by using an alkaline compound of nickel, and performing heat preservation reaction, and then filtering the obtained mixed system to obtain the nickel chloride solution after removing chromium and a chromium-containing filter residue, and the method is especially suitable for deep purification of trivalent chromium (Cr 3+ ) and hexavalent chromium (Cr 6+ ) in a high-concentration nickel chloride system, and can be widely applied to the production fields of new energy battery grade, electroplating grade and high-purity chemical grade nickel chloride.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgy, and particularly relates to a method for removing chromium impurities from nickel chloride solution and its application. Background Technology

[0002] Nickel chloride is a core raw material in new energy batteries, electroplating, catalysis, and precision alloy preparation, and its purity directly determines the performance and quality of the end products. Currently, nickel chloride solutions mainly originate from laterite nickel ore, hydrochloric acid leaching of nickel sulfide ore, regeneration of nickel-iron alloy and stainless steel waste, electroplating wastewater, and sludge recycling. These raw materials commonly contain chromium impurities, forming Cr-containing compounds. 3+ A mixed system of nickel chloride, in which Cr 3+ The content can reach 0.5~3g / L. Chromium impurities are extremely harmful to nickel chloride products and production processes: they not only poison the electroplating solution and cause the plating layer to turn black and peel, but also cause lattice distortion of the battery cathode material and shorten the cycle life.

[0003] Existing nickel chloride solution chromium removal technologies mainly include neutralization precipitation, redox-precipitation, solvent extraction, and ion exchange, but all have significant drawbacks: neutralization precipitation results in large nickel co-precipitation losses (5%~15%), incomplete chromium removal (residual Cr > 50 ppm), and inability to remove Cr. 6+ Although the redox-precipitation method can reduce Cr 6+ However, problems still exist, such as nickel loss (3%~8%), high nickel content in slag, and difficulty in resource utilization of chromium; solvent extraction method has expensive extractants and complicated operation, the selectivity of high chlorine system decreases, and organic phase entrainment easily contaminates the product; ion exchange chelating resin method has high resin cost, low adsorption capacity, poor salt resistance, frequent regeneration, and is difficult to adapt to long-term stable operation of high concentration nickel chloride system.

[0004] In addition, high concentrations of Cl - In the environment, Ni 2+ With Cr 3+ It will form a stable complex [CrCl6] 3- This further increases the difficulty of separation, making it difficult for existing technologies to simultaneously meet the industry's demands for deep purification (Cr≤5 ppm), low cost, environmental friendliness, and chromium resource utilization. Therefore, developing an efficient, economical, and green method for removing chromium from nickel chloride solution has become crucial to overcoming the industry's bottleneck. Summary of the Invention

[0005] The main objective of this invention is to provide a method for removing chromium impurities from nickel chloride solution and its application in the preparation of high-purity nickel chloride. Addressing the shortcomings of existing technologies, this invention provides a method for removing chromium impurities from nickel chloride solution, solving problems such as poor selectivity, significant nickel loss, incomplete chromium removal, high cost, and significant environmental impact. This method achieves the removal of chromium impurities from nickel chloride solution. 3+ Cr6+ Deep removal of chromium enables resource recovery and reduces production energy consumption and environmental costs.

[0006] To achieve the above objectives, the present invention provides a method for removing chromium impurities from a nickel chloride solution, comprising the following steps: S1. Add hydrochloric acid to the nickel chloride solution to adjust the pH to 1.0~3.0. S2. Add FeCl3 to the system obtained in step S1, adjust the pH of the system to 3.5~4.5 with a nickel alkaline compound, keep the reaction at a constant temperature, and filter the resulting mixture to obtain a nickel chloride solution after chromium removal and a chromium-containing filter residue.

[0007] The reaction principle of this invention is: Cr in an acidic medium 6+ Selective reduction and high-temperature co-precipitation of goethite-chromium hydroxide. Specifically, in step S1, the pH of the solution is first adjusted to 1.0-3.0 with hydrochloric acid. This strongly acidic condition ensures that FeCl3 can be fully dissolved and uniformly dispersed in step S2, avoiding uneven precipitation or colloid formation caused by excessively high local pH, thus laying the foundation for the subsequent co-precipitation reaction, while maintaining a pure chloride system and avoiding the introduction of other anionic impurities. In S2, FeCl3 is added to the resulting solution, and the pH is adjusted to 3.5-4.5 with a basic nickel compound. At this point, Fe... 3+ Hydrolysis occurs to form goethite FeO(OH) precipitate, which exhibits high selectivity and acts as a carrier for adsorption and reaction with Cr. 3+ This forms a stable composite precipitate FeO(OH)·Cr(OH)3 (a coprecipitate of goethite and chromium hydroxide), thereby removing Cr from the solution. 3+ The concentration was reduced to below ppm, and the FeO(OH)·Cr(OH)3 filter residue was finally separated by filtration. This principle fully utilizes the Fe in the high-chlorine system. 3+ The preferential formation of goethite at specific pH and temperature enables deep selective removal of Cr while avoiding the introduction of foreign impurities, significantly improving nickel recovery.

[0008] According to some embodiments of the present invention, the basic compound of nickel includes at least one of nickel hydroxide and nickel carbonate.

[0009] According to some embodiments of the present invention, in step S1, if the nickel chloride solution contains Cr 6+ This also includes adding nickel powder to a nickel chloride solution to remove Cr-containing compounds. 6+ Reduced to Cr 3+ .

[0010] This invention is in Cr-containing 6+ Add nickel powder at that time, and Cr 6+ Completely reduced to Cr 3+ (Reaction formula: 2Cr)6+ + 3Ni → 2Cr³ + +3Ni² + ).

[0011] According to some embodiments of the present invention, in step S1, nickel and Cr in the nickel powder 6+ The molar ratio is 2.25 to 3.0:1.

[0012] According to some embodiments of the present invention, in step S1, in some embodiments, the nickel powder and Cr 6+ The molar ratio is 2.25 to 3.0:1. The molar ratio can be, for example, 2.25:1, 2.5:1, 2.75:1, 3.0:1, or any value between 2.25 and 3.0:1.

[0013] According to some embodiments of the present invention, in step S2, FeCl3 and Cr 3+ The molar ratio is 0.8 to 2.0:1.

[0014] According to some embodiments of the present invention, the FeCl3 and Cr 3+ The molar ratio is 0.8 to 2.0:1. The molar ratio can be, for example, 0.8:1, 1.0:1, 1.2:1, 1.5:1, 2.0:1 or any value between 0.8 and 2.0:1.

[0015] The control of the molar ratio mentioned above in step S2 ensures that Fe³ + Sufficient hydrolysis generates a large amount of goethite FeO(OH) as a carrier, enabling the reaction with Cr³⁺. + The highly efficient and selective co-precipitation process removes the Cr content in the nickel chloride solution to below 5 ppm, while avoiding the problems of incomplete chromium removal due to insufficient FeCl3 dosage or increased nickel loss and excessive filter residue due to excessive dosage.

[0016] According to some embodiments of the present invention, in step S2, the temperature of the heat preservation reaction is 80~95°C, and the heat preservation reaction time is 30~60 min.

[0017] According to some embodiments of the present invention, in step S2, the chromium-containing filter residue comprises FeO(OH)·Cr(OH)3.

[0018] According to some embodiments of the present invention, the heat preservation reaction time is 30 to 60 minutes. The temperature can be, for example, any value between 80°C, 85°C, 90°C, 95°C, or 80 to 95°C; the heat preservation reaction time can be, for example, any value between 30 minutes, 40 minutes, 50 minutes, 60 minutes, or 30 to 60 minutes.

[0019] According to some embodiments of the present invention, step S2 further includes rinsing the filter residue, and the rinsing liquid obtained from rinsing is added to the nickel chloride solution in step S1.

[0020] According to some embodiments of the present invention, in the nickel chloride solution, Ni 2+ Concentration of 100~250 g / L, Cr 3+ Concentration of 0.5~3 g / L, Cr 6+ The concentration is 0.0001~0.5g / L.

[0021] The present invention also provides the application of the method for removing chromium impurities from nickel chloride solution in the preparation of nickel chloride.

[0022] According to some embodiments of the present invention, the nickel chloride includes new energy battery-grade nickel chloride, electroplating-grade nickel chloride, or chemical-grade nickel chloride.

[0023] 1. This invention utilizes a combined process of pretreatment, reduction, selective precipitation, and deep purification to first remove Cr... 6+ Completely reduced to Cr 3+ Then, ferric chloride is added and the pH value is adjusted with nickel hydroxide or nickel carbonate to cause co-precipitation of iron and chromium, which can reduce the Cr content in the nickel chloride solution to below 5 ppm, meeting the purity requirements of new energy battery grade and high-purity chemical grade nickel chloride, and the Cr removal rate can reach more than 99.9%.

[0024] 2. Using nickel hydroxide or nickel carbonate to adjust the pH avoids the introduction of foreign impurities; nickel loss can be controlled below 1%, and the nickel recovery rate is ≥99%, which greatly improves product profitability; the filter residue washing liquid is recycled, which further reduces the loss of nickel entrainment.

[0025] 3. The FeO(OH)·Cr(OH)3 filter residue produced by precipitation can be used for the preparation of chromium salts and chromium concentrates, realizing the recycling of chromium resources; the entire process has no harmful gas emissions, the wastewater can be recycled after treatment, the amount of hazardous waste generated is reduced by more than 80%, the environmental disposal cost is reduced, and it is in line with the development trend of green metallurgy.

[0026] 4. Capable of handling nickel chloride solutions of varying concentrations and chromium valence states, suitable for various scenarios such as mine leaching, waste recycling, and electroplating wastewater treatment. It can handle high-concentration Cl... - The system can still maintain a stable chromium removal effect, solving the problem of poor selectivity in high-chlorine systems of existing technologies. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0029] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0030] The following are specific examples of the present invention: Example 1 The nickel chloride solution processed in this embodiment is derived from the leaching solution of recycled nickel-iron alloy stainless steel waste, and its composition is as follows: Ni 2+ Concentration 120 g / L, Cr 3+ Concentration 2.5 g / L, Cr 6+ Concentration 100 mg / L.

[0031] A method for removing chromium impurities from a nickel chloride solution comprises the following steps: S1. Take 1000 mL of the nickel chloride solution to be treated, add hydrochloric acid to adjust the pH to 2.0, then add 23 mg of nickel powder, and add Cr... 6+ All reduced to Cr 3+ Stir at 250 r / min for 30 min; S2.1. Slowly add FeCl3 solid to the solution obtained in step S1. The amount of FeCl3 added is Cr 3+ The theoretical molar amount was increased to 1 times, and the temperature was raised to 90℃. Simultaneously, the pH was adjusted to 3.5–4.5 using solid nickel hydroxide, and the reaction was maintained at this temperature for 2 hours. This allowed iron ions to form goethite FeO(OH) and react with Cr. 3+ Co-precipitation forms FeO(OH)·Cr(OH)3; S2.2 Filter the mixture after the reaction to obtain a nickel chloride solution after chromium removal and FeO(OH)·Cr(OH)3 coprecipitate filter residue; rinse the filter residue with 50 mL of deionized water after filtration. S2.3. The obtained nickel chloride solution after chromium removal is evaporated, concentrated, crystallized, and dried to obtain a high-purity nickel chloride product.

[0032] Test results: 12.5g of dry filter residue, nickel content 6.3%, nickel recovery rate 99.4%. The purified nickel chloride solution contained 1.6 mg / L of Cr and 135 g / L of Ni, with a Cr removal rate of 99.94%. The nickel chloride product contained 24.0% of nickel and ≤0.001% of chromium.

[0033] Example 2 The nickel chloride solution processed in this embodiment is derived from the leaching solution of recycled nickel-iron alloy stainless steel waste, and its composition is as follows: Ni 2+ Concentration 150 g / L, Cr 3+ Concentration 2.8 g / L, Cr 6+ Concentration 50 mg / L.

[0034] A method for removing chromium impurities from a nickel chloride solution comprises the following steps: S1. Take 1000 mL of the nickel chloride solution to be treated, add hydrochloric acid to adjust the pH to 2.0, then add 11 mg of nickel powder, and remove the chromium impurities. 6+ All reduced to Cr 3+ Stir at 250 r / min for 30 min; S2.1. Slowly add FeCl3 solid to the solution obtained in step S1. The amount of FeCl3 added is Cr 3+ The temperature was raised to 90℃ using 1.5 times the theoretical molar amount of nickel hydroxide, while simultaneously adjusting the pH to 3.5-4.5 with solid nickel hydroxide. The reaction was maintained at this temperature for 2 hours, allowing iron ions to form goethite FeO(OH) and react with Cr. 3+ Co-precipitation forms FeO(OH)·Cr(OH)3; S2.2 Filter the mixture after the reaction to obtain a nickel chloride solution after chromium removal and FeO(OH)·Cr(OH)3 coprecipitate filter residue; rinse the filter residue with 50 mL of deionized water after filtration. S2.3. The nickel chloride solution obtained in step S2.2 after chromium removal is evaporated, concentrated, crystallized, and dried to obtain a high-purity nickel chloride product.

[0035] Test results: 16.1g of dry filter residue, 7.1% nickel content, 99.3% nickel recovery rate, 2 mg / L Cr content and 165 g / L Ni content in the purified nickel chloride solution, 99.93% Cr removal rate, 24.2% nickel content and ≤0.001% chromium content in the nickel chloride product.

[0036] Example 3 The nickel chloride solution processed in this embodiment is derived from the leaching solution of recycled nickel-iron alloy stainless steel waste, and its composition is as follows: Ni 2+ Concentration 200 g / L, Cr 3+ Concentration 2.5 g / L, Cr 6+ Concentration 0.08 mg / L.

[0037] A method for removing chromium from a nickel chloride solution includes the following steps: S1. Take 1000 mL of the nickel chloride solution to be treated, add hydrochloric acid to the solution, and adjust the pH of the solution to 1.0~3.0, because Cr 6+ For concentrations less than 2 mg / L, no nickel powder reduction is required. S2.1. Slowly add ferric chloride solid to the nickel chloride solution, the amount added being Cr³ + The solution was prepared at twice the theoretical molar amount, with the dissolution temperature controlled at 90℃. The mixture was stirred for 60 min while maintaining the temperature. Simultaneously, the pH was adjusted to 3.5-4.5 using solid nickel carbonate. The reaction was maintained for 2 h, and FeO(OH)·Cr(OH)3 precipitate was formed. S2.2 Filter the mixture using a Buchner funnel to obtain filter residue and nickel chloride filtrate after chromium removal; rinse the filter residue with 50 mL of deionized water. S2.3. The deeply purified nickel chloride solution is evaporated, concentrated, crystallized, and dried to obtain a high-purity nickel chloride product.

[0038] Test results: 17.3g of dry filter residue, nickel content 10.7%, nickel recovery rate 99.2%, Cr content in the purified nickel chloride solution is 1.5mg / L, Ni content is 220g / L, Cr removal rate is 99.94%, nickel content in the nickel chloride product is 24.2%, and chromium content is ≤0.001%.

[0039] Comparative Example 1 This comparative example changes the pH adjuster, replacing the nickel-based alkaline compound with NaOH, while the other conditions remain the same as in Example 1.

[0040] Comparative Example 1 used NaOH instead of the alkaline compound for nickel to adjust the pH. The pH changed too quickly, making it impossible for Fe to react. 3+ Effectively generates goethite FeO(OH) carrier.

[0041] Comparative Example 2 In this comparative example, the temperature in step S2.1 was changed; the temperature was not increased, and the reaction was carried out at room temperature. The other conditions were the same as in Example 1.

[0042] Comparative Example 2 underwent a coprecipitation reaction at room temperature, but it was unable to cause Fe to... 3+ Effective formation of goethite FeO(OH) support, leading to Cr 3+ Insufficient co-precipitation leads to poorer chromium removal.

[0043] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for removing chromium impurities from a nickel chloride solution, characterized in that, Includes the following steps: S1. Add hydrochloric acid to the nickel chloride solution to adjust the pH to 1.0~3.

0. S2. Add FeCl3 to the system obtained in step S1, adjust the pH of the system to 3.5~4.5 with a nickel alkaline compound, keep the reaction at a constant temperature, and filter the resulting mixture to obtain a nickel chloride solution after chromium removal and a chromium-containing filter residue.

2. The method for removing chromium impurities from nickel chloride solution according to claim 1, characterized in that, In step S1, if the nickel chloride solution contains Cr 6+ This also includes adding nickel powder to a nickel chloride solution to remove Cr-containing compounds. 6+ Reduced to Cr 3+ .

3. The method for removing chromium impurities from nickel chloride solution according to claim 2, characterized in that, In step S1, nickel in the nickel powder reacts with Cr 6+ The molar ratio is 2.25 to 3.0:

1.

4. The method for removing chromium impurities from nickel chloride solution according to claim 2, characterized in that, In step S2, FeCl3 and Cr 3+ The molar ratio is 0.8 to 2.0:

1.

5. The method for removing chromium impurities from a nickel chloride solution according to claim 1, characterized in that, In step S2, the temperature of the heat preservation reaction is 80~95℃, and the heat preservation reaction time is 30~120 min.

6. The method for removing chromium impurities from a nickel chloride solution according to claim 1, characterized in that, In step S2, the chromium-containing filter residue includes FeO(OH)·Cr(OH)3.

7. The method for removing chromium impurities from a nickel chloride solution according to claim 1, characterized in that, Step S2 also includes rinsing the filter residue, and the rinsing solution obtained from rinsing is added to the nickel chloride solution in step S1.

8. The method for removing chromium impurities from a nickel chloride solution according to claim 1, characterized in that, In the nickel chloride solution, Ni 2+ Concentration of 100~250 g / L, Cr 3+ Concentration of 0.5~3 g / L, Cr 6+ The concentration is 0.0001~0.5g / L.

9. The application of the method for removing chromium impurities from nickel chloride solution as described in any one of claims 1 to 8 in the preparation of nickel chloride.

10. The application according to claim 9, characterized in that, The nickel chloride includes new energy battery-grade nickel chloride, electroplating-grade nickel chloride, or chemical-grade nickel chloride.