Duplex method for preparing high-purity nickel sulfate and recovering hydrogen energy

Abstract

The invention provides a duplex method for preparing high-purity nickel sulfate and recovering hydrogen energy. The duplex method comprises the following steps: firstly adding a nickel metal source into a heteropoly acid solution, stirring for reaction, filtering to remove impurities to obtain filtrate, then adsorbing nickel ions in the filtrate by using resin to obtain adsorbed resin and hydrogen source liquid, then washing the adsorbed resin by using sulfuric acid to obtain washing liquor, and drying the washing liquor to obtain the nickel-containing hydrogen source. Evaporating and concentrating the washing liquid, cooling and crystallizing, then carrying out solid-liquid separation to obtain high-purity nickel sulfate, and finally thermally catalyzing the hydrogen source liquid through a hydrogen evolution catalyst to release hydrogen. The duplex method provided by the invention realizes preparation of high-purity nickel sulfate for new energy batteries (such as Li, Na and K batteries) and economical recovery of hydrogen energy at the same time, and improves the economical efficiency of the preparation process of the high-purity nickel sulfate.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen energy, and specifically relates to a dual process for the preparation of high-purity nickel sulfate and hydrogen energy recovery. Background Art

[0002] Nickel sulfate is an important inorganic chemical product with the chemical formula NiSO4. It appears as a yellowish-green powder or a bright green crystalline solid of NiSO4·6H2O, is easily soluble in water, and its aqueous solution is acidic. As the core product in the nickel salt series, nickel sulfate has extensive applications in the electroplating industry, battery materials, catalyst preparation, ceramic colorants, and other fields. With the rapid development of the new energy vehicle industry, nickel sulfate, as the main raw material for the precursor of the cathode material of ternary lithium batteries, has seen an explosive growth in market demand. According to industry data statistics, the global annual output of nickel sulfate has increased from approximately 200,000 tons in 2015 to over 800,000 tons in 2023, with more than 60% of the production capacity being used to meet the demand in the power battery field. This rapid growth has not only promoted the technological innovation of traditional production processes but also encouraged enterprises to continuously explore more efficient and environmentally friendly production methods. The main current industrial production processes of nickel sulfate include the metal nickel dissolution method, waste recycling method, nickel concentrate pressure acid leaching method, nickel iron dissolution method, and electrolysis method, etc. These methods have their own characteristics in terms of raw material adaptability, production cost, environmental protection indicators, etc., and together constitute a diversified technology system for modern nickel sulfate production.

[0003] Among them, the metal nickel dissolution method, as a traditional production process, its basic principle is to utilize the chemical reaction between metal nickel and sulfuric acid under specific conditions to generate a nickel sulfate solution. This process can use electrolytic nickel plates with a purity ≥99.8% or waste materials with a high nickel content as raw materials. After mechanical crushing or tablet pressing to form metal particles with a larger surface area, they are then put into a reaction kettle equipped with a steam heating device. During the reaction process, it is necessary to strictly control the sulfuric acid concentration (the initial concentration is usually controlled at 20 - 30%), the reaction temperature (maintained at 80 - 90°C), and the stirring speed. By adding concentrated sulfuric acid in stages, the acidic environment of the reaction system is maintained. In the later stage of the reaction, hydrogen peroxide and other substances are added as oxidants to redissolve the possible nickel hydroxide formed to ensure the complete conversion of nickel. The outstanding advantage of this process is the high purity of the product (up to the electroplating grade standard), the simple process flow, and relatively low equipment investment, which is especially suitable for the electroplating industry with strict impurity control requirements. However, during the operation of this process, hydrogen evolution occurs. On the one hand, the bubbles hinder the dissolution of the metal, and on the other hand, the hydrogen cannot be effectively collected, which may cause hydrogen embrittlement. Most importantly, the hydrogen cannot be stored, resulting in a large amount of energy waste, unable to achieve higher economic value, and means need to be adopted to avoid potential explosions.

[0004] In summary, in view of the energy loss in the dissolution of metallic nickel and the recycling of nickel waste, a method with higher safety and economy needs to be developed. Summary of the Invention

[0005] The present invention aims to solve at least one of the above technical problems existing in the prior art. To this end, the present invention provides a dual method for preparing high-purity nickel sulfate and recovering hydrogen energy, which realizes the method of economically recovering hydrogen energy while producing high-purity nickel sulfate for new energy batteries (such as Li, Na, K batteries), and improves the economy of the process of producing high-purity nickel sulfate.

[0006] The first aspect of the present invention provides a dual method for preparing high-purity nickel sulfate and recovering hydrogen energy, comprising the following steps:

[0007] S1: Adding a nickel metal source to a heteropolyacid solution, stirring and reacting, and then filtering to remove impurities to obtain a filtrate;

[0008] S2: Adsorbing nickel ions in the filtrate with a resin to obtain an adsorbed resin and a hydrogen source solution;

[0009] S3: Washing the adsorbed resin with sulfuric acid to obtain a washing solution, evaporating and concentrating the washing solution, cooling and crystallizing, and then performing solid-liquid separation to obtain high-purity nickel sulfate;

[0010] S4: Thermally catalyzing the hydrogen source solution through a catalyst to release hydrogen gas.

[0011] One technical solution of the dual method for preparing high-purity nickel sulfate and recovering hydrogen energy of the present invention has at least the following beneficial effects:

[0012] The dual method of the present invention makes full use of the high hydrogen storage capacity of the heteropolyacid with high reducibility and its redox reversibility. Specifically:

[0013] In step S1, due to the high solubility and multi-electron reduction characteristics of the heteropolyacid, it can provide enough H + to support the dissolution of a large amount of nickel metal. The heteropolyacid has a dissolution capacity of 0.5 M or more, and each heteropolyacid molecule also carries multiple H + which helps the rapid dissolution of nickel. When nickel metal dissolves in the heteropolyacid solution, the heteropolyacid HPA forms the corresponding heteropoly blue H x PB. The following reaction occurs:

[0014] (x - 1)Ni(s) + 2HPA + 2(x - 1)H + →(x - 1)Ni 2+ (aq) + 2H x PB

[0015] In step S2, an ion exchange resin is used to filter the heteropolyacid solution containing nickel, and active groups such as sulfonic acid groups therein are used to efficiently adsorb nickel ions; the following reaction mainly occurs:

[0016] 2R-SO3 - H + +Ni 2+ →(R-SO3 - )2Ni 2+ +2H +

[0017] In step S3, nickel ions are ion-exchanged with sulfuric acid to desorb nickel sulfate and make it exist in the liquid phase, i.e., the washing solution; the following reaction occurs:

[0018] (R-SO3 - )2Ni 2+ +H2SO4→2R-SO3 - H + +NiSO4

[0019] In step S4, thermal catalytic heating and a hydrogen evolution catalyst are used to accelerate the hydrogen evolution of the reduced heteropolyacid, and hydrogen can be quickly produced and collected; the following reaction occurs:

[0020] 2H x PB→2HPA+(x-1)H2

[0021] The present invention effectively separates the process of dissolving nickel to produce nickel sulfate from the process of hydrogen production, avoiding serious waste of hydrogen energy resources in the preparation process of high-purity NiSO4. Among them, nickel sulfate can be used to prepare the positive electrode material of the battery, and hydrogen can be used for power generation, industrial emergency power supply, etc. Therefore, the process method provided by the present invention improves the economy and environmental protection of the preparation of high-purity nickel sulfate by the metal nickel dissolution method.

[0022] The present invention uses heteropolyacid as an acidic solution to dissolve nickel, and the heteropolyacid has excellent redox reversibility, which can realize the reuse of the acid solution, effectively save the use of strong acids, and improve the safety and economy of the preparation process of high-purity nickel sulfate.

[0023] The raw materials used in the present invention are either industrial waste or cheap raw materials in the chemical industry. Therefore, the double-link method of the present invention effectively reduces the cost. The process method provided by the present invention has a simple process flow and is conducive to industrial promotion.

[0024] The high-purity nickel sulfate of the present invention refers to nickel sulfate with a purity ≥ 99.99% (with an error of 0.01%).

[0025] According to some embodiments of the present invention, the nickel metal source includes at least one of nickel flakes, nickel balls, and nickel meshes.

[0026] According to some embodiments of the present invention, the unit mass of the nickel metal source can be 0.1 to 10 g.

[0027] According to some embodiments of the present invention, the nickel metal source can be refined.

[0028] According to some embodiments of the present invention, the refining process includes screening and crushing the nickel metal source to obtain crushed materials.

[0029] The crushing process has an activation effect. Crushing in advance can increase the contact area, improve the nickel dissolution rate, and reduce the time cost.

[0030] According to some embodiments of the present invention, the crushing methods include but are not limited to cutting, ball milling, etc.

[0031] According to some embodiments of the present invention, the concentration of the heteropolyacid solution is 0.05 to 0.7 mol / L.

[0032] According to some embodiments of the present invention, the concentration of the heteropolyacid solution is 0.05 to 0.1 mol / L.

[0033] According to some embodiments of the present invention, the concentration of the heteropolyacid solution is 0.05 to 0.3 mol / L.

[0034] According to some embodiments of the present invention, the concentration of the heteropolyacid solution is 0.05 to 0.5 mol / L.

[0035] According to some embodiments of the present invention, the concentration of the heteropolyacid solution is 0.1 to 0.5 mol / L.

[0036] According to some embodiments of the present invention, the concentration of the heteropolyacid solution is 0.2 to 0.7 mol / L.

[0037] According to some embodiments of the present invention, in the heteropolyacid solution, the heteropolyacid includes at least one of phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, cobalt tungstate and their salts.

[0038] According to some embodiments of the present invention, the concentration of the phosphotungstic acid solution is 0.05 to 0.5 mol / L.

[0039] According to some embodiments of the present invention, the concentration of the silicotungstic acid solution is 0.2 to 0.7 mol / L.

[0040] According to some embodiments of the present invention, the concentration of the phosphomolybdic acid solution is 0.05 to 0.1 mol / L.

[0041] According to some embodiments of the present invention, the concentration of the cobalt tungstate solution is 0.05 to 0.3 mol / L.

[0042] According to some embodiments of the present invention, the resin includes at least one of a hydrogen ion exchange resin and a sodium ion exchange resin. The purpose of the resin is to adsorb and separate the target nickel metal ions and realize the reuse of the heteropolyacid.

[0043] According to some embodiments of the present invention, the resin is a sulfonic acid group hydrogen ion exchange resin, and the resin dosage is 2-50 g.

[0044] According to some embodiments of the present invention, the resin is a sulfonic acid group hydrogen ion exchange resin, and the resin dosage is 2-10 g.

[0045] According to some embodiments of the present invention, the resin is a sulfonic acid group hydrogen ion exchange resin, and the resin dosage is 5-50 g.

[0046] According to some embodiments of the present invention, the resin is a sulfonic acid group hydrogen ion exchange resin, and the resin dosage is 10-40 g.

[0047] According to some embodiments of the present invention, the mass-volume ratio of the nickel metal source to the heteropolyacid solution is 1 g:0.05-0.5 L.

[0048] According to some embodiments of the present invention, the concentration of the sulfuric acid is 0.5-10 mol / L.

[0049] According to some embodiments of the present invention, the concentration of the sulfuric acid is any value of 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, 5.5 mol / L, 6 mol / L, 6.5 mol / L, 7 mol / L, 7.5 mol / L, 8 mol / L, 8.5 mol / L, 9 mol / L, 9.5 mol / L, 10 mol / L or a range value formed by any two of them, such as 5-7 mol / L.

[0050] According to some embodiments of the present invention, the concentration of the sulfuric acid is 2-4 mol / L.

[0051] According to some embodiments of the present invention, the concentration of the sulfuric acid is 2-5 mol / L.

[0052] According to some embodiments of the present invention, the concentration of the sulfuric acid is 1-4 mol / L.

[0053] According to some embodiments of the present invention, the concentration of the sulfuric acid is 3-4 mol / L.

[0054] According to some embodiments of the present invention, the temperature of the evaporation and concentration is 100-150 °C.

[0055] According to some embodiments of the present invention, the instrument for evaporation and concentration may be at least one of a universal electric furnace and a flat electric heater.

[0056] According to some embodiments of the present invention, the temperature for cooling crystallization is 10 - 50 °C.

[0057] According to some embodiments of the present invention, the temperature for cooling crystallization is 10 - 30 °C.

[0058] According to some embodiments of the present invention, the temperature for cooling crystallization is 20 - 25 °C.

[0059] According to some embodiments of the present invention, the temperature for cooling crystallization is 15 - 27 °C.

[0060] According to some embodiments of the present invention, the temperature for cooling crystallization is 15 - 20 °C.

[0061] Evaporation and concentration, cooling crystallization, means performing high-temperature water removal and cooling crystallization, and using the change in solubility of nickel sulfate in concentrated sulfuric acid with temperature to precipitate it from the solution.

[0062] In step S3, after solid-liquid separation, the product is washed, and the washing liquid can be ethanol, and the water content is controlled within 5%.

[0063] According to some embodiments of the present invention, the hydrogen evolution catalyst includes at least one of platinum-carbon and Pt metal.

[0064] According to some embodiments of the present invention, the addition amount of the catalyst is 0.1 - 10 g of the catalyst added per liter of the hydrogen source liquid.

[0065] According to some embodiments of the present invention, the addition amount of the catalyst is 1 - 3 g of the catalyst added per liter of the hydrogen source liquid.

[0066] According to some embodiments of the present invention, the addition amount of the catalyst is 0.5 - 4 g of the catalyst added per liter of the hydrogen source liquid.

[0067] According to some embodiments of the present invention, the addition amount of the catalyst is 0.2 - 1 g of the catalyst added per liter of the hydrogen source liquid.

[0068] According to some embodiments of the present invention, in step S4, when adding the hydrogen evolution catalyst, stirring can be performed, and the stirring speed is 800 - 1500 rpm.

[0069] The method of stirring includes magnetic stirring. The function of stirring is to increase the mass transfer rate during the dissolution of nickel. The speed and duration of stirring are not limited as long as the nickel source can be dissolved.

[0070] According to some embodiments of the present invention, the temperature of the thermal catalysis is 25 to 90 °C.

[0071] According to some embodiments of the present invention, the temperature of the thermal catalysis can be any value among 25 °C, 30 °C, 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, 90 °C or a range value formed by any two of them, such as 50 °C to 70 °C.

[0072] According to some embodiments of the present invention, the time of the thermal catalysis is 1 to 48 h.

[0073] According to some embodiments of the present invention, the time of the thermal catalysis can be any value among 1 h, 5 h, 10 h, 15 h, 20 h, 25 h, 30 h, 35 h, 40 h, 45 h, 48 h or a range value formed by any two of them, such as 24 to 36 h. Description of the Drawings

[0074] Figure 1 is a schematic flow chart of the dual method of the present invention.

[0075] Figure 2 is the XRD pattern of nickel sulfate obtained in Example 1 of the present invention.

[0076] Figure 3 is a physical picture of nickel sulfate obtained in Example 1 of the present invention.

[0077] Figure 4 is the SEM image of nickel sulfate in Example 1 of the present invention.

[0078] Figure 5 is the SEM image of nickel sulfate in Example 2 of the present invention. Detailed Embodiments

[0079] The following will clearly and completely describe the concept and technical effects generated by the present invention in combination with the embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

[0080] In the description of the present invention, the description referring to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0081] Unless otherwise specified, "room temperature" in the present invention means 25°C ± 5°C.

[0082] Unless otherwise specified, "about" in the present invention means an allowable error within ±2%.

[0083] For those not specified with specific conditions in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified with the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0084] Example 1

[0085] This example provides a dual process method for preparing battery-grade high-purity nickel sulfate by dissolving nickel and achieving economic recovery of hydrogen energy. The process schematic diagram is as Figure 1 shown. The specific steps are as follows:

[0086] D1: Weigh 580 g of phosphotungstic acid and dissolve it in 1 L of water to prepare a solution with a concentration of 0.2 mol / L, and stir at 800 rpm until completely dissolved.

[0087] D2: Add 10 g of nickel flakes to the above phosphotungstic acid solution, and keep stirring at 800 rpm until completely dissolved.

[0088] D3: Filter the solution after the reaction in D2 by suction filtration to obtain the liquid-phase target sample.

[0089] D4: Pass the liquid phase obtained in D3 through a resin column containing 40 g of hydrogen ion exchange resin under normal pressure, and collect the liquid phase after passing through the column (i.e., the hydrogen source liquid) and the resin after complete adsorption.

[0090] D5: Repressurize and pack the resin after complete adsorption obtained in D4 into a column, and prepare sulfuric acid with a concentration of 3 mol L -1 Add 70 mL of sulfuric acid to the resin column, and collect the liquid phase after passing through the column again (i.e., the washing solution).

[0091] D6: Evaporate and concentrate the liquid phase obtained in D5 at 110°C to obtain a concentrated sulfuric acid solution of nickel sulfate, and cool and crystallize it.

[0092] D7: Filter the mixture obtained in D6 to separate the solid from the liquid, obtaining a mother liquor and a filter residue.

[0093] The above mother liquor can be returned to D5 for dilution and reuse, specifically equivalent to the application of concentrated sulfuric acid.

[0094] D8: Dry the solid obtained in D7 and collect high-purity nickel sulfate.

[0095] D9: Place the liquid phase obtained in D4 (i.e., the hydrogen source solution) into a closed device under a nitrogen atmosphere, stir at 500 rpm, control the temperature of the device to 30 °C, add 0.025 g of Pt / C, and collect the gas using the water displacement method to obtain a nitrogen-hydrogen mixture. Nitrogen-hydrogen separation can be carried out subsequently.

[0096] The solution after hydrogen production above can be returned to the nickel dissolution reaction in D2, specifically equivalent to the reuse of an aqueous solution of phosphotungstic acid.

[0097] In this example, the hydrogen ion exchange resin was purchased from Sinopharm Chemical Reagent Co., Ltd., with the model of sodium-type 732 cation exchange resin, and was converted to the hydrogen form by treatment with sulfuric acid before use.

[0098] The size of the nickel sheet is ~0.01 * 10.6 * 10.6 cm (about 10 g), and it was cut to the target mass before use.

[0099] Example 2

[0100] This example provides a dual process method for preparing battery-grade high-purity nickel sulfate by dissolving nickel and achieving economical recovery of hydrogen energy. The specific steps are different from those in Example 1 in that:

[0101] (1) In step D1, the amount of phosphotungstic acid used is 288 g.

[0102] (2) In step D2, the amount of nickel sheet used is changed to 5 g.

[0103] (3) In step D4, the amount of resin used is 30 g.

[0104] (4) In step D5, the amount of sulfuric acid used is 40 mL.

[0105] Example 3

[0106] This example provides a dual process method for preparing battery-grade high-purity nickel sulfate by dissolving nickel and achieving economical recovery of hydrogen energy. The specific steps are different from those in Example 1 in that:

[0107] (1) In step D1, the amount of phosphotungstic acid used is 1000 g.

[0108] (2) In step D2, the amount of nickel sheet used is 20 g.

[0109] (3) In step D4, the amount of resin used is 50 g.

[0110] (4) In step D5, the amount of sulfuric acid used is 90 mL.

[0111] Example 4

[0112] This example provides a dual - process method for preparing battery - grade high - purity nickel sulfate by dissolving nickel and achieving economic hydrogen energy recovery. The specific steps are different from those of Example 1 in that:

[0113] (1) In step D1, the amount of phosphotungstic acid used is 690 g.

[0114] (2) In step D2, the amount of nickel flakes used is 12 g.

[0115] (3) In step D5, the amount of sulfuric acid used is 65 mL.

[0116] Example 5

[0117] This example provides a dual - process method for preparing battery - grade high - purity nickel sulfate by dissolving nickel and achieving economic hydrogen energy recovery. The specific steps are different from those of Example 1 in that:

[0118] (1) In step D1, the amount of cobalt tungstic acid used is 872 g.

[0119] (2) In step D2, the amount of nickel flakes used is 20 g.

[0120] (3) In step D4, the amount of resin used is 50 g.

[0121] (4) In step D5, the amount of sulfuric acid used is 90 mL.

[0122] Example 6

[0123] This example provides a dual - process method for preparing battery - grade high - purity nickel sulfate by dissolving nickel and achieving economic hydrogen energy recovery. The specific steps are different from those of Example 1 in that:

[0124] (1) In step D1, the amount of silicotungstic acid used is 575 g.

[0125] (2) In step D2, the amount of nickel flakes used is 12 g.

[0126] (3) In step D5, the amount of sulfuric acid used is 65 mL.

[0127] Comparative Example 1

[0128] This example provides a dual - process method for preparing battery - grade high - purity nickel sulfate by dissolving nickel and achieving economic hydrogen energy recovery. The specific steps are as follows:

[0129] D1: Prepare a 3 mol / L -1 sulfuric acid solution,

[0130] D2: Add 10 g of nickel flakes to the solution in D1, and stir at 800 rpm until the nickel is completely dissolved.

[0131] D3: Evaporate and concentrate at 110 °C to obtain a concentrated sulfuric acid solution of nickel sulfate, and then cool and crystallize.

[0132] D4: Perform suction filtration on the mixture obtained in D3 to separate the solid and liquid, obtaining a mother liquor and a filter residue.

[0133] D5: Dry the solid obtained in D4 and collect high-purity nickel sulfate.

[0134] Test Example

[0135] This test example tested the residual amount of nickel ions in the liquid phase after nickel was dissolved and adsorbed by heteropolyacid, the nickel content in the solution after desorption, and the mass of high-purity nickel sulfate solid.

[0136] Table 1 Comparison of Results of Examples and Comparative Examples

[0137] Nickel sulfate mass Recovery rate Example 1 24.10 91.40％ Example 2 10.60 80.40％ Example 3 48.72 92.39％ Example 4 27.83 87.96％ Example 5 48.45 91.88％ Example 6 29.07 91.87％ Comparative Example 1 24.75 93.86％

[0138] In Table 1, the calculation method of the recovery rate is as follows:

[0139]

[0140] In the examples and comparative examples, the purity of nickel sulfate is 99.99%.

[0141] Table 2 Comparison of Hydrogen Production Amounts of Each Example

[0142] Hydrogen production volume (L) Example 1 Step D9 2.46 Example 2 Step D9 0.89 Example 3 Step D9 5.23 Example 4 Step D9 2.55 Example 5 Step D9 3.85 Example 6 Step D9 3.02 Comparative Example 1 — —

[0143] The results in Table 1 and Table 2 show that the nickel sulfate preparation process provided by the present invention can recover the hydrogen generated during the nickel dissolution process while ensuring the yield. Among them:

[0144] The result comparison between Example 1 - 2 or Example 2 - 3 shows that if the dissolution amount of nickel flakes in step D2 is increased, the product yield of nickel sulfate will increase, and at the same time, the hydrogen production recovery rate can be maintained above 50%.

[0145] Comparing Examples 4 - 6 illustrates that different heteropolyacids have a greater impact on step D9 and a smaller impact on the nickel sulfate yield.

[0146] This test example tested the XRD pattern of the final product in Example 1. The results showed that the crystallization state of the obtained nickel sulfate was very good and no impurity peaks appeared. That is, the process method provided by the present invention can obtain nickel sulfate with a good crystallization state and high purity. The corresponding XRD pattern is as Figure 2As shown, all the characteristic peaks of nickel sulfate are included in the XRD pattern. The physical picture is as shown in Figure 3 .

[0147] Tested by ICP-OES and ion chromatography (specifically, the dissolved nickel sulfate after crystallization was dissolved in water for determination), the purity of nickel sulfate is as high as 99.99%.

[0148] This test example also carried out SEM tests on the samples of Example 1 and Example 2 and found that the SEM morphologies prepared were consistent, indicating that this process method can stably synthesize high-purity nickel sulfate products, as shown in Figure 4 and Figure 5 .

[0149] In summary, the process method provided by the present invention has a high extraction rate for dissolved nickel ions and can also collect hydrogen energy, and also takes into account the preparation requirements of high-purity nickel sulfate. Therefore, the industrial practicability of this process method is high. At the same time, there are various choices of raw material types, and the raw materials can be regulated according to the target requirements. The raw material heteropolyacid can also be recycled, and the economic value of the produced products is higher, which means that the economy of this process method is improved. In addition, the most important thing is to avoid the waste of hydrogen energy during the nickel dissolution process and greatly reduce the hydrogen energy loss.

[0150] The present invention has been described in detail above in conjunction with the embodiments. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the gist of the present invention within the scope of knowledge possessed by those of ordinary skill in the art.

Claims

1. A dual method for preparing high-purity nickel sulfate and recovering hydrogen energy, characterized in that, It includes the following steps: S1: Add a nickel metal source into a heteropolyacid solution, stir and react, then filter to remove impurities to obtain a filtrate; S2: Adsorb nickel ions in the filtrate with a resin to obtain the adsorbed resin and a hydrogen source solution; S3: Wash the adsorbed resin with sulfuric acid to obtain a washing solution, evaporate and concentrate the washing solution, cool and crystallize, and then perform solid-liquid separation to obtain high-purity nickel sulfate; S4: Thermally catalyze the hydrogen source solution through a hydrogen evolution catalyst to release hydrogen gas.

2. The dual method according to claim 1, characterized in that, In the heteropolyacid solution, the heteropolyacid includes at least one of phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, cobalt tungstate and their salts.

3. The double connection method according to claim 1, characterized in that: The concentration of the heteropolyacid solution is 0.05 - 0.7 mol / L.

4. The dual-link method according to claim 1, wherein, The resin includes at least one of a hydrogen ion exchange resin and a sodium ion exchange resin.

5. The dual method according to claim 1, wherein The mass-volume ratio of the nickel metal source to the heteropolyacid solution is 1 g:0.05 - 0.5 L.

6. The dual-link method according to claim 1, characterized in that, The concentration of the sulfuric acid is 0.5 - 10 mol / L.

7. The dual method according to claim 1, wherein The temperature of the evaporation and concentration is 100 - 150 °C.

8. The duplex method according to claim 1, wherein The temperature of the cooling and crystallization is 10 - 50 °C.

9. The dual-link method according to claim 1, wherein The hydrogen evolution catalyst includes a hydrogen evolution catalyst.

10. The dual method according to claim 1, wherein The addition amount of the hydrogen evolution catalyst is 0.1 - 10 g of the hydrogen evolution catalyst added per liter of the hydrogen source solution.

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