A method of reducing the production of crystalline material in a nickel sulfate extraction system

Abstract

The application belongs to the technical field of hydrometallurgical nickel-cobalt extraction, and particularly relates to a method for reducing the generation of crystalline substances in a nickel sulfate extraction system, comprising the following steps: adjusting the pH of a nickel sulfate solution, and washing the organic solvent by using ammonia water for saponification; then performing multi-stage extraction, wherein the ammonia saponified organic solvent enters from the first stage of extraction, the obtained loaded organic phase flows out from the last stage, the nickel sulfate solution simultaneously enters from each stage of extraction, and the obtained raffinate flows out from the first stage of extraction; then washing the loaded organic phase by using sulfuric acid; then stripping the washed loaded organic phase by using sulfuric acid and hydrogen peroxide; and finally performing ammonia removal treatment on the stripped solution to obtain a purified nickel sulfate solution. The application optimizes the liquid inlet mode, reduces the frequency of extraction system failures, and improves the production efficiency; the multi-stage ammonia removal process reduces the ammonia concentration in the system, and improves the product purity; and the ammonia removal treatment effectively recovers part of the ammonia, and realizes the recycling of resources.

Description

Technical Field

[0001] This application belongs to the field of hydrometallurgical nickel-cobalt extraction technology, specifically a method for reducing the formation of crystals in a nickel sulfate extraction system. Background Technology

[0002] In nickel extraction, the extractant is usually saponified to improve extraction efficiency. Common saponification methods include sodium soap and ammonia soap. Ammonia soap is preferred due to its higher selectivity for nickel, less tendency to form a third phase, lower operating costs, and wider marketability of byproducts. However, in actual production, when using an ammonia soap extraction system to treat nickel sulfate solutions, improper control can easily lead to the formation of ammonium nickel sulfate crystals, especially at higher nickel concentrations. This can cause greater crystal formation, leading to pipe blockage and impacting production efficiency and product quality. The formation of ammonium nickel sulfate crystals is mainly caused by excessively high ammonia and nickel concentrations in the system, and a high pH that causes the ammonium nickel sulfate to reach saturation quickly, resulting in crystal precipitation.

[0003] Currently, research indicates that researchers and practitioners in this field do not pay sufficient attention to the issue of nickel ammonium sulfate crystallization. This is mainly because the nickel concentration processed during production is relatively low, making crystallization difficult or resulting in small crystal formations that do not affect production in the short term. Alternatively, sodium soap extraction is used to directly avoid the risk of nickel ammonium sulfate crystallization. These methods all address the problem by changing the extraction system and the target material, resulting in relatively high overall operating costs. Therefore, there is an urgent need in this field for a method that, when processing high-concentration nickel sulfate using an ammonia soap extraction system, produces little or no nickel ammonium sulfate crystals without affecting nickel recovery and purity. Summary of the Invention

[0004] To address the problems existing in the prior art, this application provides a method for reducing the formation of crystals in a nickel sulfate extraction system. The method described in this application enables continuous extraction without nickel ammonium sulfate crystals, and the prepared nickel sulfate solution has high purity and low nickel loss rate.

[0005] This application discloses a method for reducing crystal formation in a nickel sulfate extraction system, comprising the following steps:

[0006] S1. Obtain a nickel sulfate solution and an organic solvent, adjust the pH of the nickel sulfate solution to obtain a first nickel sulfate solution, saponify the organic solvent with ammonia water, and then wash to obtain a first ammonia soap organic solvent;

[0007] S2. The first nickel sulfate solution is subjected to multi-stage extraction using the first ammonia soap organic solvent to obtain a first loaded organic phase and raffinate. The first ammonia soap organic solvent enters from the first extraction stage, the first loaded organic phase flows out from the last stage, and the first nickel sulfate solution enters from each extraction stage simultaneously. The raffinate flows out from the first extraction stage.

[0008] S3. Wash the first supported organic phase with sulfuric acid to obtain the second supported organic phase;

[0009] S4. The second loaded organic phase is back-extracted using second sulfuric acid and hydrogen peroxide to obtain the back-extracted solution;

[0010] S5. The stripped liquid is subjected to deammoniation treatment to obtain a second nickel sulfate solution.

[0011] In the above technical solution, in step S1, the pH of the nickel sulfate solution is first adjusted to ensure that nickel ions in the system exist in a free state, which can inhibit the complexation of nickel ions with ammonia. Then, the saponified organic solvent is washed to reduce the free ammonia in the organic solvent. These steps effectively reduce the risk of forming nickel ammonium sulfate crystals. In step S2, in the extraction stage process, the first ammonia soap organic solvent enters the mixing and clarification chamber from the first extraction stage, and the resulting first loaded organic phase flows into the washing section from the last extraction stage. During this period, the first nickel sulfate solution simultaneously enters from each extraction stage, and the final raffinate flows out from the first extraction stage. In the extraction reaction process, pH is a very important indicator. Maintaining the raffinate within a suitable pH range is essential for achieving the best results. The pH of the raffinate is mainly affected by the saponification rate of the organic phase, the pH of the nickel sulfate solution, and the phase ratio. The simultaneous entry of the nickel sulfate solution from each extraction stage can achieve uniform contact between the two phases, effectively avoiding local overconcentration and crystallization. The phase ratio can also be controlled by adjusting the influent flow rate, thereby maintaining the pH stability of the raffinate at each stage. In step S3, the first sulfuric acid is used for washing to remove free ammonia entrained in the first loaded organic phase. In step S4, hydrogen peroxide is added during back-extraction to oxidize and remove residual ammonia in the organic phase. In step S5, the back-extraction solution is deaminated to achieve ammonia-free back-extraction solution, avoiding the impact of ammonia on subsequent electrowinning, and recovering some ammonia for recycling. The resulting second nickel sulfate solution can be directly used for nickel electrowinning.

[0012] Furthermore, in step S1, the concentration of the first nickel sulfate solution is 110~150g / L, and the pH is 2~4.

[0013] Furthermore, in step S1, the concentration of the ammonia water is 5wt%~10wt%.

[0014] Furthermore, in step S1, the organic solvent comprises an extractant and an additive.

[0015] Furthermore, the extractant includes at least one of P204, P507, and CY272, the additive includes sulfonated kerosene, and the extractant is 20% to 35% vol% of the organic solvent.

[0016] The addition of sulfonated kerosene can improve the physical properties of organic solvents, such as viscosity, thereby enhancing the extraction efficiency of organic solvents.

[0017] Furthermore, in step S2, the volume flow ratio of the first ammonia soap organic solvent to the first nickel sulfate solution is 4:1 to 8:1, and the pH of the raffinate is 3.5 to 4.5.

[0018] Furthermore, in step S3, the acidity of the first sulfuric acid is 0.5N~1N, and the volume flow ratio of the first supported organic phase to the first sulfuric acid is 10:1~20:1.

[0019] Furthermore, in step S4, the acidity of the second sulfuric acid is 2N~4N, and the volume flow ratio of the second supported organic phase to the second sulfuric acid is 8:1~16:1.

[0020] Furthermore, in step S4, the concentration of hydrogen peroxide is 0.1~0.2 mol / L, and the volume flow ratio of the second loaded organic phase to the hydrogen peroxide is 200:1~500:1.

[0021] Furthermore, in step S5, the reaction temperature for the deamination treatment is 75~90℃.

[0022] This application proposes a method to reduce the formation of crystals in a nickel sulfate extraction system, which produces the following beneficial effects: by optimizing the liquid feeding method, the formation of nickel ammonium sulfate crystals is greatly reduced, the frequency of extraction system failures is lowered, and production efficiency is improved; by using a multi-stage ammonia removal process, the ammonia concentration in the system is reduced, preventing excessive ammonia from entering the final nickel sulfate product solution and improving product purity; by using ammonia removal treatment, some ammonia can be effectively recovered, realizing resource recycling. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0024] Figure 1 This is a process flow diagram for reducing the formation of crystals in the nickel sulfate extraction system in this application.

[0025] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0026] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0027] Please see Figure 1 , Figure 1 This application presents a process flow diagram for reducing crystal formation in a nickel sulfate extraction system. A method for reducing crystal formation in a nickel sulfate extraction system includes the following steps:

[0028] S1. Obtain a nickel sulfate solution and an organic solvent, adjust the pH of the nickel sulfate solution to obtain a first nickel sulfate solution, saponify the organic solvent with ammonia water, and then wash to obtain a first ammonia soap organic solvent;

[0029] Preferably, the concentration of the first nickel sulfate solution is 110~150 g / L, and the pH is 2~4; the concentration of ammonia water is 5wt%~10wt%; the organic solvent includes extractant and additives;

[0030] More preferably, the extractant includes at least one of P204, P507, and CY272, and the additive includes sulfonated kerosene; the extractant is 20 vt% to 35 vt% of an organic solvent.

[0031] Specifically, the concentration of the first nickel sulfate solution can be any one or a range between 110 g / L, 120 g / L, 130 g / L, 140 g / L, and 150 g / L; the pH can be any one or a range between 2, 2.5, 3, 3.5, and 4; the concentration of ammonia can be any one or a range between 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, and 10 wt%; and the extractant is any one or a range between 20 wt%, 25 wt%, 30 wt%, and 35 wt% of an organic solvent.

[0032] S2. The first nickel sulfate solution is extracted in multiple stages using the first ammonia soap organic solvent to obtain the first loaded organic phase and the raffinate. The first ammonia soap organic solvent enters from the first stage of extraction, the first loaded organic phase flows out from the last stage, the first nickel sulfate solution enters from each stage of extraction, and the raffinate flows out from the first stage of extraction.

[0033] Preferably, the volume flow ratio of the first ammonia soap organic solvent to the first nickel sulfate solution is 4:1 to 8:1, and the pH of the raffinate is 3.5 to 4.5.

[0034] Specifically, the volumetric flow rate ratio of the first ammonia soap organic solvent and the first nickel sulfate solution can be any one of 4:1, 5:1, 6:1, 7:1, 8:1 or any two of them, and the pH of the raffinate can be any one of 3.5, 3.7, 3.9, 4.1, 4.3, 4.5 or any two of them.

[0035] S3. Wash the first supported organic phase with sulfuric acid to obtain the second supported organic phase;

[0036] Preferably, the acidity of the first sulfuric acid is 0.5N~1N, and the volume flow ratio of the first supported organic phase to the first sulfuric acid is 10:1~20:1;

[0037] Specifically, the acidity of the first sulfuric acid can be any one of 0.5N, 0.6N, 0.7N, 0.8N, 0.9N, 1N or any two of them, and the volumetric flow rate ratio of the first supported organic phase to the first sulfuric acid can be any one of 10:1, 12:1, 14:1, 16:1, 18:1, 20:1 or any two of them.

[0038] S4. The second supported organic phase is back-extracted using second sulfuric acid and hydrogen peroxide to obtain the back-extracted solution;

[0039] Preferably, the acidity of the second sulfuric acid is 2N~4N, and the volume flow ratio of the second supported organic phase to the second sulfuric acid is 8:1~16:1; the concentration of hydrogen peroxide is 0.1~0.2mol / L, and the volume flow ratio of the second supported organic phase to hydrogen peroxide is 200:1~500:1.

[0040] Specifically, the acidity of the second sulfuric acid can be any one or any two of 2N, 2.5N, 3N, 3.5N, and 4N; the volumetric flow rate ratio of the second supported organic phase to the second sulfuric acid can be any one or any two of 8:1, 10:1, 12:1, 14:1, and 16:1; the concentration of hydrogen peroxide can be any one or any two of 0.1mol / L, 0.12mol / L, 0.14mol / L, 0.16mol / L, 0.18mol / L, and 0.2mol / L; and the volumetric flow rate ratio of the second supported organic phase to hydrogen peroxide can be any one or any two of 200:1, 300:1, 400:1, and 500:1.

[0041] S5. The stripping solution is subjected to deammoniation treatment to obtain a second nickel sulfate solution;

[0042] Preferably, the reaction temperature for deammoniation treatment is 75~90℃. In some embodiments of the present invention, a steam stripping method is used for deammoniation treatment. Specifically, steam is used to countercurrently contact the back-extraction liquid to carry out the ammonia in the back-extraction liquid. This method is highly efficient, does not introduce impurities, and the ammonia and steam mixture can be condensed to recover high-concentration ammonia water. Other deammoniation treatment methods include stripping: adding alkali to convert ammonium ions into free ammonia (NH3), and then blowing out the free ammonia by aeration or injection of a large amount of air; other methods include breakpoint chlorination: adding chlorine to oxidize ammonia into nitrogen; ion exchange: adsorption to remove ammonia; and chemical precipitation: adding magnesium salt and phosphate to form magnesium ammonium phosphate precipitate.

[0043] The technical solution of this application will be further described below with reference to specific embodiments.

[0044] Example 1

[0045] A method for reducing crystal formation in a nickel sulfate extraction system includes the following steps:

[0046] S1. Obtain a nickel sulfate solution and an organic solvent, adjust the pH of the nickel sulfate solution to obtain a first nickel sulfate solution, saponify the organic solvent with ammonia water, and then wash to obtain a first ammonia soap organic solvent;

[0047] Specifically, the nickel sulfate solution has a nickel concentration of 110 g / L and a pH of 2; the ammonia concentration is 5 wt%; and the extractant in the organic solvent is P2O4 extractant with a concentration of 20 wt%.

[0048] S2. The first nickel sulfate solution is extracted in multiple stages using the first ammonia soap organic solvent to obtain the first loaded organic phase and the raffinate. The first ammonia soap organic solvent enters from the first stage of extraction, the first loaded organic phase flows out from the last stage, the first nickel sulfate solution enters from each stage of extraction, and the raffinate flows out from the first stage of extraction.

[0049] Specifically, the volume flow ratio of the first ammonia soap organic solvent to the first nickel sulfate solution is 4:1, and the pH of the raffinate is 3.5.

[0050] S3. Wash the first supported organic phase with sulfuric acid to obtain the second supported organic phase;

[0051] Specifically, the acidity of the first sulfuric acid is 0.5N, and the volume flow ratio of the first supported organic phase to the first sulfuric acid is 10:1;

[0052] S4. The second supported organic phase is back-extracted using second sulfuric acid and hydrogen peroxide to obtain the back-extracted solution;

[0053] Specifically, the acidity of the second sulfuric acid is 2N, and the volume flow ratio of the second supported organic phase to the second sulfuric acid is 8:1; the concentration of hydrogen peroxide is 0.1 mol / L, and the volume flow ratio of the second supported organic phase to hydrogen peroxide is 200:1.

[0054] S5. The stripping solution is subjected to deammoniation treatment to obtain a second nickel sulfate solution;

[0055] Specifically, the ammonia removal process is performed using an air stripping method at a reaction temperature of 75°C.

[0056] Example 2

[0057] A method for reducing crystal formation in a nickel sulfate extraction system includes the following steps:

[0058] S1. Obtain a nickel sulfate solution and an organic solvent, adjust the pH of the nickel sulfate solution to obtain a first nickel sulfate solution, saponify the organic solvent with ammonia water, and then wash to obtain a first ammonia soap organic solvent;

[0059] Specifically, the nickel sulfate solution has a nickel concentration of 150 g / L and a pH of 4; the ammonia concentration is 10 wt%; and the extractant in the organic solvent is P2O4 extractant with a concentration of 35 wt%.

[0060] S2. The first nickel sulfate solution is extracted in multiple stages using the first ammonia soap organic solvent to obtain the first loaded organic phase and the raffinate. The first ammonia soap organic solvent enters from the first stage of extraction, the first loaded organic phase flows out from the last stage, the first nickel sulfate solution enters from each stage of extraction, and the raffinate flows out from the first stage of extraction.

[0061] Specifically, the volume flow ratio of the first ammonia soap organic solvent to the first nickel sulfate solution is 8:1, and the pH of the raffinate is 4.5.

[0062] S3. Wash the first supported organic phase with sulfuric acid to obtain the second supported organic phase;

[0063] Specifically, the acidity of the first sulfuric acid is 1N, and the volume flow ratio of the first supported organic phase to the first sulfuric acid is 20:1.

[0064] S4. The second supported organic phase is back-extracted using second sulfuric acid and hydrogen peroxide to obtain the back-extracted solution;

[0065] Specifically, the acidity of the second sulfuric acid is 4N, and the volume flow ratio of the second supported organic phase to the second sulfuric acid is 16:1; the concentration of hydrogen peroxide is 0.2 mol / L, and the volume flow ratio of the second supported organic phase to hydrogen peroxide is 500:1.

[0066] S5. The stripping solution is subjected to deammoniation treatment to obtain a second nickel sulfate solution;

[0067] Specifically, the ammonia removal process is performed using an air stripping method at a reaction temperature of 90℃.

[0068] Example 3

[0069] A method for reducing crystal formation in a nickel sulfate extraction system includes the following steps:

[0070] S1. Obtain a nickel sulfate solution and an organic solvent, adjust the pH of the nickel sulfate solution to obtain a first nickel sulfate solution, saponify the organic solvent with ammonia water, and then wash to obtain a first ammonia soap organic solvent;

[0071] Specifically, the nickel sulfate solution has a nickel concentration of 135 g / L and a pH of 3; the ammonia concentration is 8 wt%; and the extractant in the organic solvent is P2O4 extractant with a concentration of 30 wt%.

[0072] S2. The first nickel sulfate solution is extracted in multiple stages using the first ammonia soap organic solvent to obtain the first loaded organic phase and the raffinate. The first ammonia soap organic solvent enters from the first stage of extraction, the first loaded organic phase flows out from the last stage, the first nickel sulfate solution enters from each stage of extraction, and the raffinate flows out from the first stage of extraction.

[0073] Specifically, the volume flow ratio of the first ammonia soap organic solvent to the first nickel sulfate solution is 6:1, and the pH of the raffinate is 4.0;

[0074] S3. Wash the first supported organic phase with sulfuric acid to obtain the second supported organic phase;

[0075] Specifically, the acidity of the first sulfuric acid is 0.8N, and the volume flow ratio of the first supported organic phase to the first sulfuric acid is 14:1;

[0076] S4. The second supported organic phase is back-extracted using second sulfuric acid and hydrogen peroxide to obtain the back-extracted solution;

[0077] Specifically, the acidity of the second sulfuric acid is 4N, and the volume flow ratio of the second supported organic phase to the second sulfuric acid is 12:1; the concentration of hydrogen peroxide is 0.15 mol / L, and the volume flow ratio of the second supported organic phase to hydrogen peroxide is 300:1.

[0078] S5. The stripping solution is subjected to deammoniation treatment to obtain a second nickel sulfate solution;

[0079] Specifically, the ammonia removal process is performed using an air stripping method at a reaction temperature of 80℃.

[0080] Example 4

[0081] A method for reducing crystal formation in a nickel sulfate extraction system includes the following steps:

[0082] S1. Obtain a nickel sulfate solution and an organic solvent, adjust the pH of the nickel sulfate solution to obtain a first nickel sulfate solution, saponify the organic solvent with ammonia water, and then wash to obtain a first ammonia soap organic solvent;

[0083] Specifically, the nickel sulfate solution has a nickel concentration of 135 g / L and a pH of 4; the ammonia concentration is 6 wt%; and the extractant in the organic solvent is P2O4 extractant with a concentration of 30 wt%.

[0084] S2. The first nickel sulfate solution is extracted in multiple stages using the first ammonia soap organic solvent to obtain the first loaded organic phase and the raffinate. The first ammonia soap organic solvent enters from the first stage of extraction, the first loaded organic phase flows out from the last stage, the first nickel sulfate solution enters from each stage of extraction, and the raffinate flows out from the first stage of extraction.

[0085] Specifically, the volume flow ratio of the first ammonia soap organic solvent to the first nickel sulfate solution is 6:1, and the pH of the raffinate is 4.2.

[0086] S3. Wash the first supported organic phase with sulfuric acid to obtain the second supported organic phase;

[0087] Specifically, the acidity of the first sulfuric acid is 1N, and the volume flow ratio of the first supported organic phase to the first sulfuric acid is 14:1.

[0088] S4. The second supported organic phase is back-extracted using second sulfuric acid and hydrogen peroxide to obtain the back-extracted solution;

[0089] Specifically, the acidity of the second sulfuric acid is 3.5N, and the volume flow ratio of the second supported organic phase to the second sulfuric acid is 10:1; the concentration of hydrogen peroxide is 0.15mol / L, and the volume flow ratio of the second supported organic phase to hydrogen peroxide is 300:1.

[0090] S5. The stripping solution is subjected to deammoniation treatment to obtain a second nickel sulfate solution;

[0091] Specifically, the ammonia removal process is performed using an air stripping method at a reaction temperature of 90℃.

[0092] Comparative Example 1

[0093] A method for nickel sulfate extraction includes the following steps:

[0094] S1. Obtain a nickel sulfate solution and an organic solvent, adjust the pH of the nickel sulfate solution to obtain a first nickel sulfate solution, and saponify the organic solvent with ammonia water to obtain a first ammonia soap organic solvent.

[0095] Specifically, the nickel sulfate solution has a nickel concentration of 110 g / L and a pH of 2; the ammonia concentration is 5 wt%; and the extractant in the organic solvent is P2O4 extractant with a concentration of 20 wt%.

[0096] S2. The first nickel sulfate solution is extracted in multiple stages using the first ammonia soap organic solvent to obtain the first loaded organic phase and the raffinate. The first ammonia soap organic solvent enters from the first stage of extraction, the first loaded organic phase flows out from the last stage, the first nickel sulfate solution enters from the last stage of extraction, and the raffinate flows out from the first stage of extraction.

[0097] Specifically, the volume flow ratio of the first ammonia soap organic solvent to the first nickel sulfate solution is 4:1, and the pH of the raffinate is 3.5.

[0098] S3. Wash the first supported organic phase with sulfuric acid to obtain the second supported organic phase;

[0099] Specifically, the acidity of the first sulfuric acid is 0.5N, and the volume flow ratio of the first supported organic phase to the first sulfuric acid is 10:1;

[0100] S4. Use the second sulfuric acid to back-extract the second supported organic phase to obtain the back-extracted solution, which is the second nickel sulfate solution.

[0101] Specifically, the acidity of the second sulfuric acid is 2N, and the volume flow ratio of the second supported organic phase to the second sulfuric acid is 8:1.

[0102] The comparative example uses traditional process steps. The difference from Example 1 is that the organic solvent after saponification is not washed in step S1; the liquid feeding method is different in step S2; hydrogen peroxide is not added during back-extraction in step S4; and the liquid after back-extraction is not deaminated.

[0103] Comparative Example 2

[0104] A method for nickel sulfate extraction includes the following steps:

[0105] S1. Obtain a nickel sulfate solution and an organic solvent, adjust the pH of the nickel sulfate solution to obtain a first nickel sulfate solution, saponify the organic solvent with ammonia water, and then wash to obtain a first ammonia soap organic solvent;

[0106] Specifically, the nickel sulfate solution has a nickel concentration of 110 g / L and a pH of 2; the ammonia concentration is 5 wt%; and the extractant in the organic solvent is P2O4 extractant with a concentration of 20 wt%.

[0107] S2. The first nickel sulfate solution is subjected to multi-stage extraction using the first ammonia soap organic solvent to obtain the first loaded organic phase and the raffinate. The first ammonia soap organic solvent enters from the first stage of extraction, the first loaded organic phase flows out from the last stage, and the first nickel sulfate solution enters from the last stage of extraction, while the raffinate flows out from the first stage of extraction.

[0108] Specifically, the volume flow ratio of the first ammonia soap organic solvent to the first nickel sulfate solution is 4:1, and the pH of the raffinate is 3.5.

[0109] S3. Wash the first supported organic phase with sulfuric acid to obtain the second supported organic phase;

[0110] Specifically, the acidity of the first sulfuric acid is 0.5N, and the volume flow ratio of the first supported organic phase to the first sulfuric acid is 10:1;

[0111] S4. The second supported organic phase is back-extracted using second sulfuric acid and hydrogen peroxide to obtain the back-extracted solution;

[0112] Specifically, the acidity of the second sulfuric acid is 2N, and the volume flow ratio of the second supported organic phase to the second sulfuric acid is 8:1; the concentration of hydrogen peroxide is 0.1 mol / L, and the volume flow ratio of the second supported organic phase to hydrogen peroxide is 200:1.

[0113] S5. The stripping solution is subjected to deammoniation treatment to obtain a second nickel sulfate solution;

[0114] Specifically, the ammonia removal process is performed using an air stripping method at a reaction temperature of 75°C.

[0115] This comparative example uses the multi-stage ammonia removal process from Example 1, but retains the traditional liquid inlet method.

[0116] Comparative Example 3

[0117] A method for nickel sulfate extraction includes the following steps:

[0118] S1. Obtain a nickel sulfate solution and an organic solvent, adjust the pH of the nickel sulfate solution to obtain a first nickel sulfate solution, and saponify the organic solvent with ammonia water to obtain a first ammonia soap organic solvent.

[0119] Specifically, the nickel sulfate solution has a nickel concentration of 110 g / L and a pH of 2; the ammonia concentration is 5 wt%; and the extractant in the organic solvent is P2O4 extractant with a concentration of 20 wt%.

[0120] S2. The first nickel sulfate solution is extracted in multiple stages using the first ammonia soap organic solvent to obtain the first loaded organic phase and the raffinate. The first ammonia soap organic solvent enters from the first stage of extraction, the first loaded organic phase flows out from the last stage, the first nickel sulfate solution enters from each stage of extraction, and the raffinate flows out from the first stage of extraction.

[0121] Specifically, the volume flow ratio of the first ammonia soap organic solvent to the first nickel sulfate solution is 4:1, and the pH of the raffinate is 3.5.

[0122] S3. Wash the first supported organic phase with sulfuric acid to obtain the second supported organic phase;

[0123] Specifically, the acidity of the first sulfuric acid is 0.5N, and the volume flow ratio of the first supported organic phase to the first sulfuric acid is 10:1;

[0124] S4. Use the second sulfuric acid to back-extract the second supported organic phase to obtain the back-extracted solution, which is the second nickel sulfate solution.

[0125] Specifically, the acidity of the second sulfuric acid is 2N, and the volume flow ratio of the second supported organic phase to the second sulfuric acid is 8:1.

[0126] This comparative example used the liquid inlet method in Example 1, but did not perform a multi-stage ammonia removal process.

[0127] To verify the crystallization of nickel ammonium sulfate after adopting different technical solutions, the operating status of the nickel sulfate extraction system after adopting the solutions of each embodiment and the comparative embodiment is recorded in Table 1:

[0128] Table 1

[0129]

[0130] As can be seen from the above embodiments and comparative examples, after adopting the technical solution of this application, the frequency of malfunctions in the extraction system due to the formation of nickel ammonium sulfate crystals is significantly reduced, and the nickel recovery rate and product purity are also improved accordingly. By adjusting and optimizing the parameters, even better extraction results can be achieved.

[0131] This application proposes a method to reduce the formation of crystals in a nickel sulfate extraction system, which produces the following beneficial effects: by optimizing the liquid feeding method, the formation of nickel ammonium sulfate crystals is greatly reduced, the frequency of extraction system failures is lowered, and production efficiency is improved; by using a multi-stage ammonia removal process, the ammonia concentration in the system is reduced, preventing excessive ammonia from entering the final nickel sulfate product solution and improving product purity; by using ammonia removal treatment, some ammonia can be effectively recovered, realizing resource recycling.

[0132] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. All equivalent structural transformations made using the content of this application's specification under the inventive concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A method for reducing the formation of crystals in a nickel sulfate extraction system, characterized in that, Includes the following steps: S1. Obtain a nickel sulfate solution and an organic solvent, adjust the pH of the nickel sulfate solution to obtain a first nickel sulfate solution, the pH of the first nickel sulfate solution being 2-4, saponify the organic solvent with ammonia water, and then wash to obtain a first ammonia soap organic solvent; S2. The first nickel sulfate solution is subjected to multi-stage extraction using the first ammonia soap organic solvent to obtain a first loaded organic phase and raffinate. The first ammonia soap organic solvent enters from the first extraction stage, the first loaded organic phase flows out from the last stage, and the first nickel sulfate solution enters from each extraction stage simultaneously. The raffinate flows out from the first extraction stage. S3. Wash the first supported organic phase with sulfuric acid to obtain the second supported organic phase; S4. The second loaded organic phase is back-extracted using second sulfuric acid and hydrogen peroxide to obtain the back-extracted solution; S5. The stripped liquid is subjected to deammoniation treatment to obtain a second nickel sulfate solution.

2. The method for reducing crystal formation in a nickel sulfate extraction system according to claim 1, characterized in that, In step S1, the concentration of the first nickel sulfate solution is 110~150 g / L.

3. The method for reducing crystal formation in a nickel sulfate extraction system according to claim 1, characterized in that, In step S1, the concentration of the ammonia water is 5wt%~10wt%.

4. The method for reducing crystal formation in a nickel sulfate extraction system according to claim 1, characterized in that, In step S1, the organic solvent includes an extractant and an additive.

5. The method for reducing crystal formation in a nickel sulfate extraction system according to claim 4, characterized in that, The extractant includes at least one of P204, P507, and CY272, the additive includes sulfonated kerosene, and the extractant is 20% to 35% of the organic solvent.

6. The method for reducing crystal formation in a nickel sulfate extraction system according to claim 1, characterized in that, In step S2, the volume flow ratio of the first ammonia soap organic solvent to the first nickel sulfate solution is 4:1 to 8:1, and the pH of the raffinate is 3.5 to 4.

5.

7. The method for reducing crystal formation in a nickel sulfate extraction system according to claim 1, characterized in that, In step S3, the acidity of the first sulfuric acid is 0.5N~1N, and the volume flow ratio of the first supported organic phase to the first sulfuric acid is 10:1~20:

1.

8. The method for reducing crystal formation in a nickel sulfate extraction system according to claim 1, characterized in that, In step S4, the acidity of the second sulfuric acid is 2N~4N, and the volume flow ratio of the second supported organic phase to the second sulfuric acid is 8:1~16:

1.

9. The method for reducing crystal formation in a nickel sulfate extraction system according to claim 1, characterized in that, In step S4, the concentration of hydrogen peroxide is 0.1~0.2 mol / L, and the volume flow ratio of the second loaded organic phase to the hydrogen peroxide is 200:1~500:

1.

10. The method for reducing crystal formation in a nickel sulfate extraction system according to claim 1, characterized in that, In step S5, the reaction temperature for the deamination treatment is 75~90℃.

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