Process for the preparation of anhydrous nickel fluoride
Anhydrous nickel fluoride crystals were directly generated by stepwise gradient alkali addition and low-temperature stirring, which solved the problems of high-temperature calcination and impurity introduction, and achieved efficient and low-cost preparation of anhydrous nickel fluoride, which is suitable for anhydrous fluorination reaction and battery materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGSU ELECTRONIC TECH ENVIRONMENTAL CO LTD
- Filing Date
- 2026-04-07
- Publication Date
- 2026-06-12
AI Technical Summary
Existing technologies are difficult to use efficiently and energy-savingly to prepare high-purity anhydrous nickel fluoride from nickel-containing waste. Furthermore, traditional methods are prone to introducing impurities or require high-temperature calcination, resulting in high production costs and poor product performance.
Anhydrous nickel fluoride crystals are directly generated by using a stepwise gradient alkali addition method, combined with low-temperature stirring and constant-temperature aging, and by controlling the reaction environment, avoiding high-temperature calcination and the introduction of impurities. This method includes steps such as stepwise addition of ammonia, low-temperature stirring, centrifugal separation, and low-temperature negative pressure drying.
This method enables the efficient and low-cost preparation of high-purity anhydrous nickel fluoride, significantly reducing energy consumption, increasing nickel content and yield, and avoiding high-temperature calcination and impurity contamination. It is suitable for anhydrous fluorination reactions and battery material preparation.
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Figure CN122187151A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of nickel fluoride recycling and purification technology, and in particular to a process for preparing anhydrous nickel fluoride. Background Technology
[0002] High-purity nitrogen trifluoride (NF3) is widely used in integrated circuits, semiconductor manufacturing, and other fields as an excellent plasma etching gas. Industrially, it is mainly produced through electrolysis. During this process, the nickel anode plate is gradually corroded by the electrolyte, generating a large amount of nickel fluoride-containing waste residue and waste liquid. For the recycling of this nickel-containing waste, various treatment methods have been developed. For example, a method for treating nickel-containing waste residue generated by nitrogen trifluoride electrolysis, disclosed in a Chinese patent, can recover solid nickel fluoride from the waste residue through steps such as oxidation dissolution, pH adjustment, filtration, and crystallization. However, the nickel fluoride product obtained by this method readily forms nickel fluoride tetrahydrate under conventional crystallization conditions.
[0003] However, nickel tetrahydrate has significant drawbacks in practical applications: firstly, its poor solubility in water makes it inconvenient to use; secondly, due to the large proportion of water of crystallization in its molecular weight, the nickel content of the product is only 5%-12wt%, which is insufficient to meet the requirements of high nickel loading scenarios. In contrast, anhydrous nickel fluoride contains no water of crystallization and has a theoretical nickel content as high as 59wt%, offering significant advantages in ease of use and high effective nickel content, making it valuable for applications in anhydrous fluorination reactions and battery material preparation.
[0004] Currently, obtaining anhydrous nickel fluoride from nickel-containing waste typically requires high-temperature (above 300°C) calcination and dehydration of the recovered nickel tetrahydrate. This process is extremely energy-intensive, requires stringent equipment, and significantly increases production costs. There have also been attempts to directly prepare anhydrous nickel fluoride using carbonate precipitation conversion, but the reaction generates a large amount of carbon dioxide bubbles, easily introducing impurities such as sodium, potassium, or carbonate ions, affecting product purity. Therefore, how to directly, efficiently, and energy-savingly prepare high-purity anhydrous nickel fluoride from nickel-containing waste has become a pressing technical problem to be solved in this field. Summary of the Invention
[0005] In order to efficiently and energy-savingly prepare anhydrous nickel fluoride from nickel-containing waste, this application provides a process for preparing anhydrous nickel fluoride.
[0006] A process for preparing anhydrous nickel fluoride includes the following steps: S1. Pretreatment: Provide nickel-fluorine etch waste liquid and adjust the pH value with alkaline solution; S2, Insulation and Stirring: During the pH adjustment process in step S1, the reaction temperature is controlled at 30~50°C and stirring is carried out; S3, Static Aging: The liquid after the reaction in step S2 is allowed to stand and age. S4. Centrifugal separation: The aged liquid from step S3 is subjected to solid-liquid separation to obtain wet nickel fluoride containing free water. S5. Drying: The wet nickel fluoride material containing free water obtained in step S4 is dried using a cyclone separator to obtain the nickel fluoride product. In step S1, the alkaline solution is ammonia water, and the ammonia water is added in steps, with the proportion of the mass of ammonia water added in each step gradually increasing to the total mass of ammonia water.
[0007] The preparation process described in this application reduces the stability of hydrated ions by utilizing a mild thermal environment of 30-50°C, while simultaneously controlling the supersaturation of the system within the optimal range for nucleation and growth using a stepwise gradient alkali addition method. These two factors work synergistically to create a low-energy-barrier, highly ordered crystalline microenvironment. This environment effectively inhibits the formation of hydrogen bonds, thereby interfering with the binding of water molecules to nickel and fluoride ions, and effectively preventing water of crystallization from entering the crystal lattice. This allows the crystal to directly form an anhydrous structure during growth, thus enabling the direct precipitation of high-purity anhydrous nickel fluoride crystals from an aqueous solution without the introduction of high-temperature calcination.
[0008] Compared to existing technologies that first generate nickel tetrahydrate and then dehydrate it at high temperature, this application not only directly generates anhydrous nickel fluoride crystals during the precipitation stage, eliminating the energy-intensive step of high-temperature calcination (above 300°C) and significantly reducing production costs; the preparation process of this application also avoids the introduction of sodium, potassium or carbonate impurities caused by the use of carbonate methods, thereby greatly improving the nickel content and yield of the product.
[0009] Preferably, the ammonia water in step S1 is added in four steps, with the percentage of ammonia water added in each step relative to the total mass of ammonia water being 8-12 wt%, 18-22 wt%, 28-32 wt%, and 38-42 wt%, respectively; more preferably, the percentage of ammonia water added in each step relative to the total mass of ammonia water is 10 wt%, 20 wt%, 30 wt%, and 40 wt%, respectively. The inventors verified through experiments that the initial addition of a small amount of ammonia is to "induce crystals" in the nickel-fluorine etching waste liquid, avoiding excessively high instantaneous supersaturation that could lead to impurity encapsulation. The gradually increased proportion in the later stages ensures complete precipitation of nickel ions when the driving force is insufficient in the later stages of the reaction. This specific ratio ensures a gradual increase in the pH value of the reaction system, avoiding localized over-alkalinity, thereby guaranteeing the integrity of crystal growth and achieving the desired nickel content in the final product.
[0010] If ammonia is added all at once, the crystal water content in the product will increase, resulting in a significant reduction in the nickel content and a severe impact on the yield. If it is added in stages but in an improper ratio, it will lead to a violent reaction or incomplete precipitation. Compared to the case where the ammonia is added in a distributed manner according to the above percentage, both the nickel content and yield of the product will be reduced accordingly.
[0011] Preferably, in step S1, the time interval between each addition of ammonia is 0.4 to 0.6 hours; more preferably, the time interval between each addition of ammonia is 0.5 hours.
[0012] By adopting the above technical solution, it is ensured that each batch of ammonia water can fully react with the hydrogen and nickel ions in the waste liquid, allowing sufficient time for the generated nickel fluoride crystal nuclei to grow and age. If the interval is too short, the reaction of the previous batch will not be completed, leading to disordered crystal form; if the interval is too long, production efficiency will be reduced. This parameter guarantees the density of the crystals and the completeness of the reaction.
[0013] Preferably, the concentration of ammonia in step S1 is 10~20wt%.
[0014] Analysis of the experiments showed that too low a concentration (e.g., <10%) introduces excessive free water, increasing the burden on subsequent drying and potentially promoting hydrate formation; while too high a concentration (e.g., >20%) results in an overly vigorous reaction, making it difficult to control the rate of pH increase, easily leading to localized high pH, generating nickel hydroxide impurities, or causing crystals to encapsulate the mother liquor. A concentration of 10-20%, combined with stepwise addition, achieves the smoothest pH adjustment.
[0015] Preferably, in step S2, after adding ammonia water at each step, the temperature difference of the reaction is controlled to be within 5°C.
[0016] By employing the above technical solution, a strict temperature difference control within ±2.5°C, i.e., a total fluctuation of 5°C, can ensure the constancy of the crystal growth environment. Excessive temperature fluctuations can cause the crystal growth rate to fluctuate wildly, easily leading to lattice defects or polymorphic mixing due to the incorporation of hydrates. A constant temperature environment is conducive to the formation of a regular anhydrous nickel fluoride crystal structure.
[0017] Preferably, before step S1, the initial pH of the nickel-fluorine etching waste liquid is 0~3; after step S1, the pH of the reaction system is adjusted to 3.5~4.0.
[0018] In a strongly acidic environment (pH < 3), nickel fluoride exists in ionic form. When the pH is raised to 3.5–4.0, the solubility product of nickel fluoride reaches a critical point; this pH range is the "golden window" for the formation of anhydrous nickel fluoride. If the pH is too low (< 3.5), precipitation will be incomplete, resulting in low nickel recovery. If the pH is too high (> 4.0), nickel ions in the solution will easily combine with hydroxide ions to form nickel hydroxide precipitate, or cause ammonium fluoride to decompose, thereby reducing product purity and nickel content.
[0019] Preferably, in step S2, the stirring rate is 20~40 r / min.
[0020] This rotation speed is sufficient to ensure uniform mixing of materials within the reactor, preventing localized ammonia enrichment that could lead to sudden pH changes. It also avoids the strong shear forces caused by high rotation speeds that could damage the growing crystal structure. Low-speed stirring promotes the formation of large, easily filterable crystals, reducing the amount of mother liquor encapsulated by the crystals.
[0021] Preferably, in step S3, the temperature of the static aging process is maintained at 30~50°C.
[0022] The aging process is a crystal dissolution-redeposition process. Aging at a temperature of 30-50°C accelerates the adjustment of the internal crystal structure, causing small crystals to dissolve and large crystals to grow, thereby improving the integrity and purity of the crystals. Simultaneously, this temperature range coincides with the reaction temperature, avoiding the increase in water encapsulation in the crystals caused by cooling.
[0023] Preferably, in step S4, the centrifugal separation speed is 2800~3200 r / min; more preferably, the centrifugal separation speed is 3000 r / min.
[0024] This rotational speed provides sufficient centrifugal force to efficiently separate nickel fluoride crystals from the mother liquor, removing most of the free water and soluble impurities (such as ammonium salts). Too high a speed may cause the crystals to be over-compacted and difficult to unload, while too low a speed will result in incomplete separation. This parameter ensures that the resulting wet material has a suitable moisture content, which is beneficial for subsequent low-energy drying.
[0025] Preferably, in step S5, the drying temperature is 40~50°C and the pressure is -1000~-1600Pa.
[0026] Because the initial process has suppressed the formation of water of crystallization, the crystals contain only free water adsorbed by physical means. Under low temperature and negative pressure conditions of 40-50°C, this free water readily vaporizes and is carried away. Compared to traditional processes that require temperatures above 300°C to remove chemically bound water of crystallization, this process consumes very little energy and avoids product oxidation or decomposition caused by high temperatures, ensuring the high activity and high purity of anhydrous nickel fluoride.
[0027] In summary, this application includes at least one of the following beneficial technical effects: 1. This application creates a dynamic reaction environment that can effectively suppress hydrogen bonding by distributively adjusting pH and coordinating temperature control and stirring within a low-temperature range. This interferes with the binding of water molecules with nickel and fluoride ions, inhibiting water molecules from embedding into the crystal lattice at the crystallization source. Anhydrous nickel fluoride crystals can be directly precipitated without high-temperature calcination, greatly avoiding the high energy consumption drawbacks of traditional high-temperature dehydration above 300°C, simplifying production processes and reducing industrial production costs.
[0028] 2. This application adopts a controlled alkali process of adding ammonia water in stages and increments to precisely control the supersaturation of the reaction system, thereby achieving a crystallization control effect of first initiating crystals and then steadily growing them. This avoids the problems of impurity encapsulation and crystal form disorder caused by instantaneous alkali addition, and prevents the formation of nickel hydroxide byproducts due to local over-alkali. It also completely eliminates the residual sodium, potassium and carbonate impurities caused by carbonate alkali adjustment, and significantly improves the purity of nickel fluoride products and the recovery rate of nickel element.
[0029] 3. This application relies on the synergistic effect of low-speed stirring, constant temperature aging, precise centrifugal separation and low-temperature negative pressure drying throughout the entire process. This ensures regular crystal growth and complete purification to remove free impurities and free water, while avoiding damage to the crystal structure or oxidative decomposition of raw materials caused by strong shearing and high temperature conditions. The result is a highly active and high-purity anhydrous nickel fluoride, which also takes into account production efficiency and energy-saving advantages. It is suitable for the industrial-scale application of resource recovery of nickel-fluorine etching waste liquid. Attached Figure Description
[0030] Figure 1 This is a product diagram of anhydrous nickel fluoride prepared in Example 1 of this application.
[0031] Figure 2 This is a diagram of the nickel fluoride product containing water of crystallization obtained in Comparative Example 1 of this application.
[0032] Figure 3 The images show the products doped with water-soluble nickel fluoride and anhydrous nickel fluoride obtained in Examples 2-3 of this application. Detailed Implementation
[0033] The present application will be further described in detail below with reference to embodiments and comparative examples: Some of the raw materials used in the examples and comparative examples: Unless otherwise specified, all raw materials used in the examples and comparative examples are commercially available products.
[0034] Typically, nickel-fluorine etching wastewater contains 0.5-2 wt% nickel, 10-22 wt% ammonium fluoride, 0-18 wt% hydrofluoric acid, and has a pH < 3. The nickel-fluorine etching waste liquid used in this application has a nickel content of 1.33 wt%, an ammonium fluoride content of 16%, a hydrofluoric acid content of 9%, and a pH < 3. Example
[0035] Example 1 A process for preparing anhydrous nickel fluoride includes the following steps: S1. Pretreatment: 1000 kg of nickel-fluorine etching waste liquid is provided. 120 kg of 15 wt% ammonia solution is added to the nickel-fluorine etching waste liquid in four steps: first, 12 kg of ammonia solution is added; second, 24 kg of ammonia solution is added; third, 36 kg of ammonia solution is added; and finally, the remaining 48 kg of ammonia solution is added. Each step is spaced 0.5 h apart. The final pH value of the reaction system is adjusted to be between 3.5 and 4.0. S2, Insulation and Stirring: During the pH adjustment process in step S1, the reaction temperature is controlled at 30~50°C and stirring is carried out at a stirring rate of 30r / min; after adding ammonia water in each step, the temperature difference of the reaction is controlled within 5°C. S3. Static aging: The liquid after the reaction in step S2 is allowed to stand and age for 1.5 hours at 30~50°C. S4. Centrifugal separation: The aged liquid from step S3 is separated into solid and liquid components using a centrifuge at a speed of 3000 r / min to obtain wet nickel fluoride containing free water. S5. Drying: The wet nickel fluoride material containing free water obtained in step S4 is dried using a cyclone separator at 40~50°C and -1000~-1600Pa pressure to obtain the nickel fluoride product.
[0036] This embodiment ultimately yielded 21 kg of nickel fluoride product. Chemical titration and purity analysis revealed a nickel content of 59 wt%, which, based on theoretical ideal results, indicates that it is anhydrous nickel fluoride. The overall nickel recovery rate was 93%. The product is pale yellow and has the following appearance characteristics. Figure 1 As shown.
[0037] Example 2 The only difference between Example 2 and Example 1 is that in Example 2, 120 kg of ammonia water with a concentration of 15 wt% was added to the nickel-fluorine etching waste liquid in four steps in step S1, was replaced by 120 kg of ammonia water with a concentration of 5 wt% being added to the nickel-fluorine etching waste liquid in four steps.
[0038] In this embodiment, 24 kg of nickel fluoride product was finally obtained. After chemical titration and purity testing, the nickel content of the product was 48 wt%, and the comprehensive nickel element recovery rate was 86%.
[0039] Example 3 The only difference between Example 3 and Example 1 is that in Example 3, 120 kg of ammonia water with a concentration of 15 wt% was added to the nickel-fluorine etching waste liquid in four steps in step S1, was replaced by 120 kg of ammonia water with a concentration of 25 wt% being added to the nickel-fluorine etching waste liquid in four steps.
[0040] In this embodiment, 22 kg of nickel fluoride product was finally obtained. After chemical titration and purity testing, the nickel content of the product was 54 wt%, and the comprehensive nickel element recovery rate was 89%.
[0041] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that in step S1 of Comparative Example 1, ammonia is added to the nickel-fluorine etching waste liquid all at once, which includes the following steps: S1. Pretreatment: Provide 1000kg of nickel-fluorine etching waste liquid, and add 120kg of 15wt% ammonia water to the nickel-fluorine etching waste liquid in one go, and finally adjust the pH value of the reaction system to within 3.5 to 4.0; S2. Keep warm and stir: During the process of adjusting the pH value in step S1, control the reaction temperature to be maintained at 30~50°C and stir at a rate of 30r / min. S3. Static aging: The liquid after the reaction in step S2 is allowed to stand and age for 1.5 hours at 30~50°C. S4. Centrifugal separation: The aged liquid from step S3 is separated into solid and liquid components using a centrifuge at a speed of 3000 r / min to obtain wet nickel fluoride containing free water. S5. Drying: The wet nickel fluoride material containing free water obtained in step S4 is dried using a cyclone separator at 40~50°C and -1000~-1600Pa pressure to obtain the nickel fluoride product.
[0042] This comparative example ultimately yielded 31 kg of nickel fluoride product containing water of crystallization. Chemical titration and purity analysis revealed a nickel content of 34 wt%, with a comprehensive nickel recovery rate of 80%. The product was light green in color and had the following appearance characteristics. Figure 2 As shown.
[0043] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that step S2 of Comparative Example 2 does not involve temperature control, and it includes the following steps: S1. Pretreatment: 1000 kg of nickel-fluorine etching waste liquid is provided. 120 kg of 15 wt% ammonia solution is added to the nickel-fluorine etching waste liquid in four steps: first, 12 kg of ammonia solution is added; second, 24 kg of ammonia solution is added; third, 36 kg of ammonia solution is added; and finally, the remaining 48 kg of ammonia solution is added. Each step is spaced 0.5 h apart. The final pH value of the reaction system is adjusted to be between 3.5 and 4.0. S2, Insulation and Stirring: During the pH adjustment process in step S1, the stirring rate is 30 r / min; S3, Static Aging: The liquid after the reaction in step S2 is allowed to stand and age for 1.5 hours; S4. Centrifugal separation: The aged liquid from step S3 is separated into solid and liquid components using a centrifuge at a speed of 3000 r / min to obtain wet nickel fluoride containing free water. S5. Drying: The wet nickel fluoride material containing free water obtained in step S4 is dried using a cyclone separator at 40~50°C and -1000~-1600Pa pressure to obtain the nickel fluoride product.
[0044] This comparative example ultimately yielded 27 kg of a mixture of water of crystallization and anhydrous nickel fluoride. Chemical titration and purity analysis revealed a nickel content of 40 wt%, with a comprehensive nickel recovery rate of 85%. The product exhibited an uneven coloration, with a mixture of pale yellow and pale green impurities, and its appearance was as follows: Figure 3 As shown.
[0045] The nickel content and overall nickel recovery rate of the nickel fluoride products measured under the preparation processes of each embodiment and comparative example are summarized and recorded in the table below: Table 1. Record of Nickel Content and Comprehensive Nickel Recovery Rate in Nickel Fluoride Products Group Nickel content (wt%) Nickel recovery yield % Example 1 59 93 Example 2 48 86 Example 3 54 89 Comparative Example 1 34 80 Comparative Example 2 40 85 Based on Examples 1-3 and Table 1, it can be seen that the concentration of ammonia water has a decisive impact on the nickel content and yield of anhydrous nickel fluoride products. Example 1, using ammonia water within the preferred concentration range, effectively suppressed the formation of water of crystallization under the synergistic effect of stepwise gradient alkali addition and temperature-controlled crystallization, achieving an ideal nickel content and optimal yield. Example 2, using low-concentration ammonia water, introduced excess free water into the system, partially offsetting the process's effect of suppressing water of crystallization, resulting in a small amount of water molecules embedding into the crystal lattice, significantly reducing the nickel content and yield of the product. Example 3, using high-concentration ammonia water, resulted in an overly vigorous reaction, with localized over-alkali leading to the formation of trace amounts of nickel hydroxide impurities or crystal encapsulation of the mother liquor; both the nickel content and yield of the product were lower than the preferred scheme. This indicates that the ammonia water concentration must be strictly controlled within the preferred range to achieve the best anhydrous crystallization effect and resource recovery efficiency.
[0046] Combining Example 1 and Comparative Example 1, and referring to Table 1, it can be seen that the method of adding ammonia has a crucial impact on the nickel content and yield of anhydrous nickel fluoride products. Example 1 used a step-by-step gradient addition of ammonia, employing a "first crystallization, then steady growth" control strategy to maintain the system's supersaturation within the optimal range of "nucleation-growth," effectively suppressing water molecule embedding into the crystal lattice, resulting in excellent nickel content and yield. Comparative Example 1 used a single-stage addition of ammonia, leading to instantaneous supersaturation, explosive crystal nucleus formation, and disordered growth. Impurities were largely encapsulated, and the high water content made it difficult to suppress crystal water, significantly reducing both the nickel content and yield. This indicates that step-by-step gradient alkali addition is the core operational method for suppressing crystal water formation and ensuring high product purity and high yield.
[0047] Combining Example 1 and Comparative Example 2, and referring to Table 1, it can be seen that strict control of the reaction temperature has a significant impact on the nickel content of the anhydrous nickel fluoride product. In Example 1, the reaction temperature fluctuation was strictly controlled after each ammonia addition, providing a stable, low-energy-barrier microenvironment for crystal growth, effectively interfering with hydrogen bond formation, inhibiting water molecules from entering the crystal lattice, and achieving an ideal nickel content in the product. In Comparative Example 2, no reaction temperature control was performed, and the temperature fluctuations in the system led to uneven crystal growth. In some areas, the temperature drop promoted the formation of mixed crystals of hydrates, resulting in a significantly lower nickel content in the product. This indicates that, based on stepwise alkali addition, strict isostatic control is crucial for achieving regular growth of anhydrous nickel fluoride crystals and avoiding hydrate doping.
[0048] This application utilizes the synergistic effect of stepwise gradient alkali addition and isothermal stirring to suppress water molecule embedding into the crystal lattice at the crystallization source, enabling the direct precipitation of anhydrous nickel fluoride crystals without high-temperature calcination, thus significantly reducing energy consumption. Furthermore, by controlling the ammonia concentration within an optimal range, the risks of introducing excessive free water at low concentrations or generating impurities at high concentrations are avoided, further ensuring product purity and yield. This application achieves high-nickel content and high-yield anhydrous nickel fluoride preparation while significantly reducing production costs, providing an efficient and energy-saving industrial pathway for the high-value resource recovery of nickel-fluoride etching wastewater.
[0049] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.
Claims
1. A process for preparing anhydrous nickel fluoride, characterized in that, Includes the following steps: S1. Pretreatment: Provide nickel-fluorine etch waste liquid and adjust the pH value with alkaline solution; S2, Insulation and Stirring: During the pH adjustment process in step S1, the reaction temperature is controlled at 30~50°C and stirring is carried out; S3, Static Aging: The liquid after the reaction in step S2 is allowed to stand and age. S4. Centrifugal separation: The aged liquid from step S3 is subjected to solid-liquid separation to obtain wet nickel fluoride containing free water. S5. Drying: The wet nickel fluoride material containing free water obtained in step S4 is dried using a cyclone separator to obtain the nickel fluoride product. In step S1, the alkaline solution is ammonia water, and the ammonia water is added in steps, with the proportion of the mass of ammonia water added in each step gradually increasing to the total mass of ammonia water.
2. The preparation process of anhydrous nickel fluoride according to claim 1, characterized in that, The ammonia water in step S1 is added in four steps, and the percentage of the mass of ammonia water added in each step relative to the total mass of ammonia water is 8-12wt%, 18-22wt%, 28-32wt%, and 38-42wt%, respectively.
3. The preparation process of anhydrous nickel fluoride according to claim 1, characterized in that, In step S1, the time interval between adding ammonia water in each step is 0.4~0.6h.
4. The preparation process of anhydrous nickel fluoride according to claim 1, characterized in that, The concentration of ammonia in step S1 is 10~20wt%.
5. The preparation process of anhydrous nickel fluoride according to claim 1, characterized in that, In step S2, after each addition of ammonia, the temperature difference of the reaction is controlled to be within 5°C.
6. The preparation process of anhydrous nickel fluoride according to claim 1, characterized in that, Before step S1, the initial pH of the nickel-fluorine etching waste liquid is 0~3; after step S1, the pH of the reaction system is adjusted to 3.5~4.
0.
7. The preparation process of anhydrous nickel fluoride according to claim 1, characterized in that, In step S2, the stirring rate is 20~40 r / min.
8. The preparation process of anhydrous nickel fluoride according to claim 1, characterized in that, In step S3, the temperature for static aging is maintained at 30~50°C.
9. The preparation process of anhydrous nickel fluoride according to claim 1, characterized in that, In step S4, the centrifugal separation speed is 2800~3200 r / min.
10. The preparation process of anhydrous nickel fluoride according to claim 1, characterized in that, In step S5, the drying temperature is 40~50°C and the pressure is -1000~-1600Pa.