Preparation method of basic nickel carbonate and mother liquor circulating sulfur removal system

Abstract

The application belongs to the technical field of inorganic carbonate preparation, and particularly relates to a preparation method of basic nickel carbonate and a mother liquor circulating sulfur removal system. The basic nickel carbonate is prepared by adopting a precipitation reaction of a nickel salt, a carbonate and a regulating agent. The regulating agent has hydrophilic hydroxyl and carboxylic acid groups, and has hydrophobic long aliphatic chains, trifluoromethyl and large steric t-butyl. After the nickel salt and the carbonate react to generate the basic nickel carbonate, the regulating agent can be adsorbed on the surface of the basic nickel carbonate precipitate through electrostatic action, intermolecular force and the like, and through steric hindrance effect, the agglomeration of the basic nickel carbonate precipitate is hindered, the precipitation adhesion speed of the basic nickel carbonate is reduced, the particle size of the basic nickel carbonate precipitate is controlled in a certain range, and the particle size uniformity of the basic nickel carbonate is improved. In addition, the regulating agent avoids impurity elements in the liquid phase from entering the formed basic nickel carbonate precipitate through coordination effect and steric hindrance effect, and thus the purity of the basic nickel carbonate is improved.

Description

Technical Field

[0001] This invention belongs to the field of inorganic carbonate preparation technology, specifically a method for preparing basic nickel carbonate and a mother liquor circulation desulfurization system. Background Technology

[0002] Basic nickel carbonate is an important inorganic fine chemical, mainly used to prepare various nickel salts, which are widely used in electroplating, electroforming, ceramic enamel pigments, and industrial catalysts. High-quality basic nickel carbonate can be used in the electronics industry. Basic nickel carbonate is usually prepared by liquid-phase precipitation, which has the advantages of simple process and wide applicability. Currently, industrially, basic nickel carbonate is mainly prepared by liquid-phase homogeneous precipitation using nickel sulfate, nickel chloride, or nickel nitrate as raw materials and sodium carbonate, sodium hydroxide, sodium bicarbonate, ammonium bicarbonate, ammonia, etc., as precipitants. However, in current industrial production processes, due to limitations in raw material selection and process control, the resulting basic nickel carbonate products not only have high impurity content but are also difficult to remove during washing.

[0003] Furthermore, the production of basic nickel carbonate typically generates mother liquor containing sulfate ions. Traditional treatment methods present several problems: ① Ineffective sulfate removal: Existing desulfurization methods struggle to reduce sulfate ions to low levels, resulting in low product purity and hindering its application in high-end fields. ② Resource waste: The mother liquor contains a large amount of valuable metal ions, such as nickel ions; direct discharge or simple treatment leads to resource waste. ③ Environmental pollution: Discharging untreated mother liquor pollutes the environment and fails to meet green and environmentally friendly production requirements.

[0004] In summary, there is an urgent need to develop a method for preparing basic nickel carbonate that can effectively reduce the impurity content of basic nickel carbonate products, as well as a system for treating and reusing the mother liquor generated during the production of basic nickel carbonate. Summary of the Invention

[0005] To address the above problems, this invention provides a method for preparing basic nickel carbonate and a mother liquor circulation desulfurization system, which solves the problems of high impurity content in currently prepared basic nickel carbonate products and the ineffective utilization of mother liquor during the production process.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing basic nickel carbonate includes the following steps: a nickel salt, a carbonate, and a regulator are subjected to a precipitation reaction, and after purification, basic nickel carbonate is obtained; the regulator is prepared as follows: (S)-tert-leucine alcohol and 2-(trifluoromethyl)acrylic acid are subjected to a Michael addition reaction to obtain an addition product, and the addition product is subjected to a Michael addition reaction with 9-octadecenoic acid to obtain an intermediate, and then the intermediate is subjected to a salt formation reaction with sodium hydroxide to obtain the regulator; the molar ratio of (S)-tert-leucine alcohol, 2-(trifluoromethyl)acrylic acid, and 9-octadecenoic acid is 1:1:1, and the molar ratio of the intermediate to sodium hydroxide is 1:3.

[0008] Preferably, the nickel salt is one or any combination of nickel sulfate, nickel sulfate hydrate, nickel chloride, and nickel chloride hydrate.

[0009] Preferably, the carbonate is ammonium carbonate.

[0010] Preferably, the precipitation reaction method is as follows: a nickel salt solution, a carbonate solution, and a regulator are stirred and mixed, wherein the concentration of the nickel salt solution is 2.0~2.4 mol / L, the concentration of the carbonate solution is 2.5~2.9 mol / L, the volume ratio of the nickel salt solution to the carbonate solution is 100~150:90~120, and 100~120 g of regulator is used for every 100 L of nickel salt solution.

[0011] Preferably, the precipitation reaction is carried out at a temperature of 50-58°C for 2.5-3.2 hours.

[0012] Preferably, the stirring rate during the precipitation reaction is 300~400 r / min.

[0013] Preferably, the Michael addition reaction of (S)-tert-leucine and 2-(trifluoromethyl)acrylic acid is carried out at a temperature of 35-40°C for 12-15 h; the Michael addition reaction of the addition product and 9-octadecenoic acid is carried out at a temperature of 60-70°C for 18-24 h.

[0014] Preferably, the purification method is as follows: the system after precipitation reaction is subjected to solid-liquid separation to obtain crude basic nickel carbonate, and then the crude basic nickel carbonate is washed and dried to obtain basic nickel carbonate.

[0015] Preferably, the washing process involves first washing the crude basic nickel carbonate with water, then washing it with a 0.4 mol / L calcium chloride solution, then washing it with water again, and finally centrifuging and filtration the system after the three washings to obtain wet basic nickel carbonate.

[0016] A mother liquor circulation desulfurization system includes a mother liquor collection tank, a pretreatment unit, a desulfurization reaction unit, a solid-liquid separation unit, and a mother liquor recovery unit; the mother liquor collection tank is used to collect the mother liquor generated in the impurity removal process of the preparation method of basic nickel carbonate as described above, and the pretreatment unit includes a filtration device and a pH adjustment tank.

[0017] The beneficial effects of the method for preparing basic nickel carbonate and the mother liquor circulation desulfurization system of the present invention are as follows:

[0018] (1) The basic nickel carbonate prepared by this invention has uniform particle size and low impurity content. The sodium content is 10~14ppm, the magnesium content is 16~19ppm, the sulfate ion content is 29~33ppm, and the iron, cobalt and calcium contents are all less than 10ppm, which meets the requirements for use of electronic grade basic nickel carbonate.

[0019] (2) The regulator used in this invention can effectively improve the particle size uniformity of basic nickel carbonate and reduce the impurity content. The regulator has hydrophilic hydroxyl and carboxylic acid groups, as well as hydrophobic long aliphatic chains, trifluoromethyl and sterically hindered tert-butyl groups. After the nickel salt and carbonate ions react to form basic nickel carbonate, the regulator can be adsorbed on the surface of the basic nickel carbonate precipitate through electrostatic interaction, intermolecular forces, etc. Through the steric hindrance effect, it hinders the aggregation of basic nickel carbonate precipitate, reduces the precipitation adhesion rate of basic nickel carbonate, and controls the particle size of basic nickel carbonate precipitate within a certain range, thereby improving its particle size uniformity. In addition, the regulator avoids impurity elements in the liquid phase from entering the formed basic nickel carbonate precipitate through coordination effect and steric hindrance, thereby improving the purity of basic nickel carbonate.

[0020] (3) The mother liquor circulation desulfurization system in this invention can realize the recycling of mother liquor, reduce the waste of valuable metal ions, reduce production costs, and at the same time reduce the discharge of mother liquor, reduce environmental pollution, and conform to the green and environmentally friendly production concept. Attached Figure Description

[0021] Figure 1 This is a schematic diagram illustrating the working principle of the basic nickel carbonate preparation process and the mother liquor circulation desulfurization system of the present invention. Detailed Implementation

[0022] To enable those skilled in the art to better understand the technical solution, the present invention will be described in detail below with reference to embodiments. The description in this part is only exemplary and explanatory, and should not be used to limit the scope of protection of the present invention in any way.

[0023] The NiSO4·6H2O solution used in Examples 1-3 and Comparative Examples 1-10 below was prepared from industrial-grade NiSO4·6H2O and water; the ammonium carbonate solution was prepared from industrial-grade ammonium carbonate and water; and the NiCl2·6H2O solution was prepared from industrial-grade NiCl2·6H2O and water. The NiSO4·6H2O solution and the ammonium carbonate solution used in Examples 1 and Comparative Examples 1-10 were the same.

[0024] I. Specific embodiments of the preparation method of basic nickel carbonate of the present invention are as follows:

[0025] Example 1

[0026] The method for preparing basic nickel carbonate in this embodiment includes the following steps:

[0027] (1) Add 100L of NiSO4·6H2O solution with a concentration of 2mol / L and 90L of ammonium carbonate solution with a concentration of 2.5mol / L to the reactor, then add 100g of regulator, stir evenly and heat to 50℃, control the stirring speed to 300r / min, stir for 2.5h, cool to room temperature and filter, the filter cake is crude basic nickel carbonate. The preparation method of the regulator is as follows: (S)-tert-leucine, 2-(trifluoromethyl)acrylic acid, triethylamine and anhydrous tetrahydrofuran in a molar ratio of 1:1:0.03:5 are added to a reaction vessel, heated to 35°C, and stirred for 12 hours. Then, a 50% (w / w) tetrahydrofuran solution of 9-octadecenoic acid is added, heated to 60°C, and stirred for 18 hours. Triethylamine and tetrahydrofuran are removed by vacuum distillation to obtain the intermediate. The molar ratio of 9-octadecenoic acid and (S)-tert-leucine is 1:1. The chemical structure of the intermediate is as follows:

[0028] .

[0029] Then, the intermediate and water in a mass ratio of 1:5 were added to a stirred tank, followed by sodium hydroxide. The mixture was stirred and reacted for 30 minutes. The water was removed by vacuum distillation, and the product was dried to obtain the regulator. The molar ratio of the intermediate to sodium hydroxide was 1:3.

[0030] (2) Add crude basic nickel carbonate and 300L of deionized water to a stirred tank for primary stirring and washing. Control the stirring speed at 150r / min, the primary stirring and washing time at 25min, and the primary stirring and washing temperature at 25℃. After stirring and washing, filter the mixture, and the filter cake is the primary washing material. Then add the primary washing material and 200L of 0.3mol / L calcium chloride solution to the stirred tank for secondary stirring and washing. Control the stirring speed at 200r / min, the secondary stirring and washing time at 35min, and the secondary stirring and washing temperature at 35℃. After washing and filtration, the filter cake becomes the secondary washing material. Then, the secondary washing material and 300L of deionized water are added to a stirred tank for tertiary stirring and washing, with the stirring speed controlled at 150r / min, the tertiary stirring and washing time at 25min, and the tertiary stirring and washing temperature at 25℃. After stirring and washing, the material is then separated by a centrifuge and dehydrated by a filter press at 4000r / min for 18min to obtain wet basic nickel carbonate. Finally, the wet basic nickel carbonate is placed in an oven and dried at 100℃ for 10h to obtain basic nickel carbonate.

[0031] Example 2

[0032] The method for preparing basic nickel carbonate in this embodiment includes the following steps:

[0033] (1) Add 120L of NiCl2·6H2O solution with a concentration of 2.2mol / L and 100L of ammonium carbonate solution with a concentration of 2.8mol / L to the reaction vessel, then add 110g of regulator, stir evenly and heat to 53℃, control the stirring speed to 350r / min, stir for 2.8h, cool to room temperature and filter, the filter cake is crude basic nickel carbonate. The preparation method of the regulator is as follows: (S)-tert-leucine, 2-(trifluoromethyl)acrylic acid, triethylamine, and anhydrous tetrahydrofuran in a molar ratio of 1:1:0.04:6 are added to a reaction vessel, heated to 38°C, and stirred for 14 hours. Then, a 52% (w / w) tetrahydrofuran solution of 9-octadecenoic acid is added, and the mixture is heated to 65°C and stirred under reflux for 19 hours. Triethylamine and tetrahydrofuran are removed by vacuum distillation to obtain the intermediate. The molar ratio of 9-octadecenoic acid and (S)-tert-leucine is 1:1. The chemical structure of the intermediate is as follows:

[0034] .

[0035] Then, the intermediate and water in a mass ratio of 1:5 were added to a stirred tank, followed by sodium hydroxide. The mixture was stirred and reacted for 40 minutes. The water was removed by vacuum distillation, and the product was dried to obtain the regulator. The molar ratio of the intermediate to sodium hydroxide was 1:3.

[0036] (2) Add crude basic nickel carbonate and 350L of deionized water to a stirred tank for primary stirring and washing. Control the stirring speed at 180r / min, the primary stirring and washing time at 28min, and the primary stirring and washing temperature at 28℃. After stirring and washing, filter the mixture, and the filter cake is the primary washing material. Then add the primary washing material and 220L of 0.35mol / L calcium chloride solution to the stirred tank for secondary stirring and washing. Control the stirring speed at 220r / min, the secondary stirring and washing time at 38min, and the secondary stirring and washing temperature at 36℃. After filtration, the filter cake becomes the secondary washing material. Then, the secondary washing material and 350L of deionized water are added to a stirred tank for tertiary stirring and washing. The stirring speed is controlled at 180r / min, the tertiary stirring and washing time is 28min, and the tertiary stirring and washing temperature is 28℃. After stirring and washing, the material is sequentially separated by a centrifuge and dehydrated by a filter press. The centrifuge speed is 4200r / min, and the centrifugation time is 19min, yielding wet basic nickel carbonate. Finally, the wet basic nickel carbonate is placed in an oven and dried at 103℃ for 10.5h to obtain basic nickel carbonate.

[0037] Example 3

[0038] The method for preparing basic nickel carbonate in this embodiment includes the following steps:

[0039] (1) Add 150L of NiSO4·6H2O solution with a concentration of 2.4mol / L and 120L of ammonium carbonate solution with a concentration of 2.9mol / L to the reactor, then add 120g of regulator, stir evenly and heat to 58℃, control the stirring speed to 400r / min, stir for 3.2h, cool to room temperature and filter, the filter cake is crude basic nickel carbonate. The preparation method of the regulator is as follows: (S)-tert-leucine, 2-(trifluoromethyl)acrylic acid, triethylamine and anhydrous tetrahydrofuran in a molar ratio of 1:1:0.05:7 are added to a reaction vessel, heated to 40°C, and stirred for 15 h. Then, a 55% (w / w) tetrahydrofuran solution of 9-octadecenoic acid is added, heated to 70°C, and stirred under reflux for 24 h. Triethylamine and tetrahydrofuran are removed by vacuum distillation to obtain the intermediate. The molar ratio of 9-octadecenoic acid and (S)-tert-leucine is 1:1. The chemical structure of the intermediate is as follows:

[0040] .

[0041] Then, the intermediate and water in a mass ratio of 1:6 were added to a stirred tank, followed by sodium hydroxide. The mixture was stirred and reacted for 50 minutes. The water was removed by vacuum distillation, and the product was dried to obtain the regulator. The molar ratio of the intermediate to sodium hydroxide was 1:3.

[0042] (2) Add crude basic nickel carbonate and 400L of deionized water to a stirred tank for primary stirring and washing. Control the stirring speed at 200r / min, the primary stirring and washing time at 30min, and the primary stirring and washing temperature at 30℃. After stirring and washing, filter the mixture, and the filter cake is the primary washing material. Then add the primary washing material and 250L of 0.4mol / L calcium chloride solution to the stirred tank for secondary stirring and washing. Control the stirring speed at 240r / min, the secondary stirring and washing time at 40min, and the secondary stirring and washing temperature at 38℃. After washing and filtration, the filter cake becomes the secondary washing material. Then, the secondary washing material and 400L of deionized water are added to a stirred tank for tertiary stirring and washing, with the stirring speed controlled at 200r / min, the tertiary stirring and washing time at 30min, and the tertiary stirring and washing temperature at 30℃. After stirring and washing, the material is then separated by a centrifuge and dehydrated by a filter press. The centrifuge speed is 4500r / min, and the centrifugation time is 20min, yielding wet basic nickel carbonate. Finally, the wet basic nickel carbonate is placed in an oven and dried at 108℃ for 11h to obtain basic nickel carbonate.

[0043] Comparative Example 1

[0044] The difference between the preparation method of basic nickel carbonate in this comparative example and the preparation method of basic nickel carbonate in Example 1 is that the amount of regulator used in step (1) of the preparation method of basic nickel carbonate in this comparative example is 0.

[0045] Comparative Example 2

[0046] The difference between the preparation method of basic nickel carbonate in this comparative example and the preparation method of basic nickel carbonate in Example 1 is only that the preparation method of the regulator in step (1) of the preparation method of basic nickel carbonate in this comparative example is as follows: (S)-tert-leucine, 2-fluoroacrylic acid, triethylamine and anhydrous tetrahydrofuran in a molar ratio of 1:1:0.03:5 are added to a reaction vessel, heated to 35°C, and stirred for 12 hours. Then, a 50% (w / w) tetrahydrofuran solution of 9-octadecenoic acid is added, heated to 60°C, and stirred for 18 hours. The triethylamine and tetrahydrofuran are removed by vacuum distillation to obtain an intermediate; the molar ratio of 9-octadecenoic acid and (S)-tert-leucine is 1:1. Finally, the intermediate and water in a mass ratio of 1:5 are added to a stirred vessel, and sodium hydroxide is added. The mixture is stirred for 30 minutes, and the water is removed by vacuum distillation. After drying, the regulator is obtained; the molar ratio of the intermediate to sodium hydroxide is 1:3.

[0047] Comparative Example 3

[0048] The difference between the preparation method of basic nickel carbonate in this comparative example and the preparation method of basic nickel carbonate in Example 1 is only that the preparation method of the regulator in step (1) of the preparation method of basic nickel carbonate in this comparative example is as follows: (S)-tert-leucine alcohol, 2,4,5-trifluorophenylpropenylic acid, triethylamine and anhydrous tetrahydrofuran in a molar ratio of 1:1:0.03:5 are added to a reaction vessel, heated to 35°C, and stirred for 12 h. Then, a tetrahydrofuran solution of 9-octadecenoic acid with a mass fraction of 50% is added, heated to 60°C, and stirred for 18 h. The triethylamine and tetrahydrofuran are removed by vacuum distillation to obtain an intermediate; the molar ratio of 9-octadecenoic acid and (S)-tert-leucine alcohol is 1:1. Finally, the intermediate and water in a mass ratio of 1:5 are added to a stirred vessel, and sodium hydroxide is added. The mixture is stirred for 30 min, and the water is removed by vacuum distillation. After drying, the regulator is obtained; wherein, the molar ratio of the intermediate and sodium hydroxide is 1:3.

[0049] Comparative Example 4

[0050] The difference between the preparation method of basic nickel carbonate in this comparative example and the preparation method of basic nickel carbonate in Example 1 is only that the preparation method of the regulator in step (1) of the preparation method of basic nickel carbonate in this comparative example is as follows: 2-amino-1-butanol, 2-(trifluoromethyl)acrylic acid, triethylamine and anhydrous tetrahydrofuran in a molar ratio of 1:1:0.03:5 are added to a reaction vessel, heated to 35°C, and stirred for 12 hours. Then, a 50% (w / w) tetrahydrofuran solution of 9-octadecenoic acid is added, heated to 60°C, and stirred for 18 hours. Triethylamine and tetrahydrofuran are removed by vacuum distillation to obtain an intermediate; the molar ratio of 9-octadecenoic acid and 2-amino-1-butanol is 1:1. Finally, the intermediate and water in a mass ratio of 1:5 are added to a stirred vessel, and sodium hydroxide is added. The mixture is stirred for 30 minutes, and the water is removed by vacuum distillation. After drying, the regulator is obtained; the molar ratio of the intermediate to sodium hydroxide is 1:3.

[0051] Comparative Example 5

[0052] The difference between the preparation method of basic nickel carbonate in this comparative example and the preparation method of basic nickel carbonate in Example 1 is only that the preparation method of the regulator in step (1) of the preparation method of basic nickel carbonate in this comparative example is as follows: (S)-tert-leucine, 2-(trifluoromethyl)acrylic acid, triethylamine and anhydrous tetrahydrofuran in a molar ratio of 1:1:0.03:5 are added to a reaction vessel, heated to 35°C, and stirred for 12 h. Then, a 50% (w / w) solution of maleic acid in tetrahydrofuran is added, heated to 60°C, and stirred for 18 h. The triethylamine and tetrahydrofuran are removed by vacuum distillation to obtain an intermediate; the molar ratio of maleic acid and (S)-tert-leucine is 1:1. Finally, the intermediate and water in a mass ratio of 1:5 are added to a stirred vessel, and sodium hydroxide is added. The mixture is stirred for 30 min, and the water is removed by vacuum distillation. After drying, the regulator is obtained; the molar ratio of the intermediate to sodium hydroxide is 1:3.

[0053] Comparative Example 6

[0054] The difference between the preparation method of basic nickel carbonate in this comparative example and the preparation method of basic nickel carbonate in Example 1 is only that the preparation method of the regulator in step (1) of the preparation method of basic nickel carbonate in this comparative example is as follows: (S)-tert-leucine, 2-(trifluoromethyl)acrylic acid, triethylamine and anhydrous tetrahydrofuran in a molar ratio of 1:1:0.03:5 are added to a reaction vessel, heated to 35°C, and stirred for 12 hours. Then, a 50% tetrahydrofuran solution of tetratetraenoic acid is added, heated to 60°C, and stirred for 18 hours. The triethylamine and tetrahydrofuran are removed by vacuum distillation to obtain an intermediate; the molar ratio of tetratetraenoic acid and (S)-tert-leucine is 1:1. Finally, the intermediate and water in a mass ratio of 1:5 are added to a stirred vessel, and sodium hydroxide is added. The mixture is stirred for 30 minutes, and the water is removed by vacuum distillation. After drying, the regulator is obtained; the molar ratio of the intermediate and sodium hydroxide is 1:3.

[0055] Comparative Example 7

[0056] The difference between the preparation method of basic nickel carbonate in this comparative example and the preparation method of basic nickel carbonate in Example 1 is that the preparation method of the regulator in step (1) of the preparation method of basic nickel carbonate in this comparative example is as follows: (S)-tert-leucine, 2-(trifluoromethyl)acrylic acid and 9-octadecenoic acid in a molar ratio of 1:1:1 are stirred evenly to obtain a mixture. The mixture and water are added to a stirred tank in a mass ratio of 1:5. Sodium hydroxide is then added and stirred for 30 minutes. The mixture is then distilled under reduced pressure to remove water and dried to obtain the regulator. The molar amount of sodium hydroxide is equal to twice the molar amount of 9-octadecenoic acid and the sum of the molar amounts of 2-(trifluoromethyl)acrylic acid in the mixture.

[0057] Comparative Example 8

[0058] The difference between the preparation method of basic nickel carbonate in this comparative example and the preparation method of basic nickel carbonate in Example 1 is that the preparation method of the regulator in step (1) of the preparation method of basic nickel carbonate in this comparative example is as follows: (S)-tert-leucine, 2-(trifluoromethyl)acrylic acid, triethylamine and anhydrous tetrahydrofuran in a molar ratio of 1:1:0.03:5 are added to the reaction vessel, heated to 35°C, and stirred for 12 hours. Then, a tetrahydrofuran solution of 9-octadecenoic acid with a mass fraction of 50% is added, heated to 60°C, and stirred for 18 hours. Then, succinic anhydride is added to the reaction vessel, stirred for 6 hours at room temperature, and triethylamine and tetrahydrofuran are removed by vacuum distillation to obtain the intermediate. The molar ratio of 9-octadecenoic acid and (S)-tert-leucine is 1:1, and the molar ratio of succinic anhydride and (S)-tert-leucine is 1:1. Then, the intermediate and water in a mass ratio of 1:5 were added to a stirred tank, followed by sodium hydroxide. The mixture was stirred and reacted for 30 minutes. The water was removed by vacuum distillation, and the product was dried to obtain the regulator. The molar ratio of the intermediate to sodium hydroxide was 1:4.

[0059] Comparative Example 9

[0060] The difference between the preparation method of basic nickel carbonate in this comparative example and the preparation method of basic nickel carbonate in Example 1 is that the regulator in step (1) of the preparation method of basic nickel carbonate in this comparative example is sodium citrate.

[0061] Comparative Example 10

[0062] The difference between the preparation method of basic nickel carbonate in this comparative example and the preparation method of basic nickel carbonate in Example 1 is that the regulator in step (1) of the preparation method of basic nickel carbonate in this comparative example is tetrasodium ethylenediaminetetraacetate.

[0063] II. Specific embodiments of the mother liquor circulation desulfurization system of the present invention are as follows:

[0064] In actual production using the methods for preparing basic nickel carbonate described in Examples 1-3, the washing mother liquor produced contains a large amount of valuable metal ions, such as nickel ions. Direct discharge or simple treatment would waste resources and pollute the environment, failing to meet the requirements of green and environmentally friendly production. Therefore, based on the aforementioned methods for preparing basic nickel carbonate, this invention further develops a highly efficient mother liquor circulation desulfurization system and a clean production process for basic nickel carbonate utilizing this system.

[0065] Example 4

[0066] The mother liquor circulation desulfurization system of this embodiment includes a mother liquor collection tank, a pretreatment unit, a desulfurization reaction unit, a solid-liquid separation unit, and a mother liquor recovery unit.

[0067] The mother liquor collection tank is a rectangular tank made of corrosion-resistant stainless steel, with a volume of 5-10 m³. 3 The pool wall is 3-5mm thick, with a drain outlet at the bottom and an inlet on the side. It is used to collect mother liquor containing sulfate ions generated during the production process. The mother liquor from the production stage is received through the inlet, and the mother liquor can be transported to the subsequent treatment unit through the drain outlet.

[0068] The pretreatment unit includes a filtration device and an equalization tank. The filtration device comprises a sand core funnel and a microporous membrane. The sand core funnel has a pore size of G4~G6 and is used for preliminary filtration of larger solid particles in the mother liquor. The microporous membrane has a pore size of 0.22~0.45μm and further removes smaller particles from the mother liquor. The sand core funnel is installed at the top inlet of the pretreatment unit, and the microporous membrane is installed at the bottom outlet of the sand core funnel. The two are connected by a sealing ring to ensure no leakage during filtration. The equalization tank is a cylindrical water tank made of carbon steel with a volume of 3~5m³. 3 The pool walls are coated with an anti-corrosion coating, and the pool is equipped with a pH monitoring electrode and an acid-base regulator addition device. The pH monitoring electrode is used to adjust the pH value of the mother liquor to a suitable range (6.5~7.5). The pH monitoring electrode monitors the pH value of the mother liquor in real time. When the pH value deviates from the set range, the acid-base regulator addition device automatically adds an appropriate amount of acid or alkali to adjust it.

[0069] The desulfurization reaction unit includes a reaction vessel and a desulfurizing agent feeding device. The reaction vessel is made of stainless steel and has a volume of 5-8 m³. 3 The reactor body is lined with an acid-resistant layer to prevent corrosion from the mother liquor. The reactor is equipped with a heating device, a stirring device, and a temperature monitoring device. The heating device uses an electric heating jacket with a heating power of 10-15kW, which can precisely control the reaction temperature between 80-100℃. The stirring device consists of a motor, a stirring shaft, and a stirring paddle. The motor power is 3-5kW, the stirring shaft speed is adjustable within the range of 100-300 r / min, and the stirring paddle adopts a double-layer turbine structure, which can effectively promote the mixing and reaction of the mother liquor and the desulfurizing agent. The desulfurizing agent feeding device is a metering pump, which adds a certain concentration of calcium chloride solution to the reactor at a certain flow rate, allowing it to fully mix and react with the mother liquor to remove sulfate ions.

[0070] The solid-liquid separation unit includes a centrifuge and a filter press. The centrifuge is a horizontal screw centrifuge with a drum diameter of 300-500 mm, a rotation speed of 3000-5000 r / min, and a separation factor of 1000-3000 g. It uses the centrifugal force generated by high-speed rotation to initially separate the mother liquor and precipitate after the reaction. Solid particles are thrown against the drum wall, while the mother liquor is discharged through the overflow port in the center of the drum. The filter press is a plate and frame filter press with polypropylene filter plates measuring 600×600 mm and a filtration pressure of 0.3-0.5 MPa. Its function is to further remove water from the precipitate, reducing its moisture content to 20%-30%.

[0071] The mother liquor recovery unit includes an intermediate storage tank and a circulation pump. The intermediate storage tank is a cylindrical tank made of polyethylene with a volume of 5-8 m³. 3 The tank wall is equipped with a liquid level monitoring device and a circulating liquid outlet; it is used to store mother liquor after desulfurization treatment. The liquid level monitoring device monitors the liquid level in the tank in real time. When the liquid level reaches the set value, the circulating pump starts to transport the mother liquor back to the production process for recycling. The circulating pump is a corrosion-resistant magnetically driven centrifugal pump with a flow rate of 2~3 m³ / h. 3 The pump has a flow rate of 10-15 m and a head of 10-15 m. It is used to provide power for the circulation of mother liquor, ensuring that the mother liquor can be smoothly transported from the intermediate storage tank back to the precipitation reaction step.

[0072] The mother liquor circulation desulfurization system in this embodiment is a supporting device for the basic nickel carbonate preparation system, and its working principle is as follows: Figure 1As shown: Nickel salt solution and carbonate solution are added to the reactor at a molar ratio of 1:1.8~2.2. The reaction temperature is controlled at 45~55℃, the stirring speed at 200~400 r / min, and the reaction time at 2~3 h. After the reaction, basic nickel carbonate precipitate is formed. The basic nickel carbonate precipitate is then washed with deionized water. The washing conditions are: washing solution to precipitate mass ratio of 3~5:1, washing temperature at 20~30℃, stirring speed at 100~200 r / min, and washing time at 20~30 min. The purpose of washing is to remove most of the soluble impurities on the precipitate surface, such as unreacted nickel salts and carbonates. A secondary wash is then performed using a 0.2–0.4 mol / L calcium chloride solution, with a washing solution-to-precipitate mass ratio of 2–4:1, a washing temperature of 30–40°C, a stirring speed of 150–300 r / min, and a washing time of 30–40 min. The purpose of this wash is to utilize the competitive reaction between calcium chloride and the residual sulfate ions on the precipitate surface to further reduce the sulfate content. A tertiary wash is then performed using deionized water, with a washing solution-to-precipitate mass ratio of 3–5:1, a washing temperature of 20–30°C, a stirring speed of 100–200 r / min, and a washing time of 20–30 min. The purpose of this wash is to remove any remaining impurities on the precipitate surface after the secondary wash, ensuring a low sulfate ion content. The system after the tertiary wash is then preliminarily separated using a centrifuge and further dehydrated using a filter press to obtain wet basic nickel carbonate solid with a water content of 10%–20%. Finally, the wet basic nickel carbonate solid is dried in an oven to obtain the basic nickel carbonate product. The mother liquor generated during each washing process is collected in a mother liquor collection tank. After treatment by a pretreatment unit, a desulfurization reaction unit, a solid-liquid separation unit, and a mother liquor recovery unit, it is recycled back to the precipitation reaction step. Automatic circulation of the mother liquor is achieved through a liquid level monitoring device and a circulation pump, ensuring the continuity and stability of the production process. The mother liquor circulation desulfurization system of this embodiment enables the recycling of mother liquor, reduces the waste of valuable metal ions, lowers production costs, and simultaneously reduces mother liquor emissions, thus reducing environmental pollution and aligning with the concept of green and environmentally friendly production.

[0073] Experimental Example

[0074] This experimental example was used to investigate the particle size and impurity content of basic nickel carbonate prepared in Examples 1-3 and Comparative Examples 1-10. The particle size was tested according to the specifications in standard GB-T19077-2016 "Particle Size Distribution - Laser Diffraction Method". The test results include D... 10 Particle size, D 50 Particle size and D 90Particle size and impurity metal content were tested according to the provisions of GB / T15337-2008 "General Rules for Atomic Absorption Spectrometry Analysis". Sulfate and chloride ion contents were determined by ion chromatography. The particle size and impurity content of the basic nickel carbonate prepared in Examples 1-3 and Comparative Examples 1-10 are shown in Table 1.

[0075] Table 1. Particle size and impurity content of basic nickel carbonate prepared in Examples 1-3 and Comparative Examples 1-10

[0076]

[0077] As can be seen from the test results in Table 1, the D of the basic nickel carbonate prepared in Examples 1-3 of this invention is... 10 Particle size, D 50 Particle size and D 90 The particle sizes were 13.8–14.7, 16.7–17.1, and 18.4–19.2 μm, respectively, D 10 Particle size, D 50 Particle size and D 90 The small difference in particle size indicates that the basic nickel carbonate prepared by this invention has a relatively uniform particle size. Furthermore, the basic nickel carbonate prepared by this invention contains 10-14 ppm sodium, 16-19 ppm magnesium, and 29-33 ppm sulfate ions. The contents of iron, cobalt, and calcium are all below 10 ppm, significantly lower than the impurity content in the basic nickel carbonate prepared in the comparative examples. This proves that the basic nickel carbonate prepared by this invention has high purity and meets the requirements for electronic-grade basic nickel carbonate.

[0078] As can be seen from Example 1 and Comparative Example 1, the regulator used in this invention can effectively improve the particle size uniformity of basic nickel carbonate and reduce the impurity content. This is because the regulator has hydrophilic hydroxyl and carboxylic acid groups, as well as hydrophobic long aliphatic chains, trifluoromethyl and sterically hindered tert-butyl groups. After the nickel salt and carbonate ions react to form basic nickel carbonate, the regulator can be adsorbed on the surface of the basic nickel carbonate precipitate through electrostatic interaction, intermolecular forces, etc. Through the steric hindrance effect, it hinders the aggregation of basic nickel carbonate precipitate, reduces the precipitation adhesion rate of basic nickel carbonate, and controls the particle size of basic nickel carbonate precipitate within a certain range, thereby improving its particle size uniformity. Furthermore, the regulator prevents impurity elements in the liquid phase from entering the formed basic nickel carbonate precipitate through coordination effect and steric hindrance, thereby improving the purity of basic nickel carbonate.

[0079] As can be seen from Example 1 and Comparative Examples 2-3, when 2-fluoroacrylic acid or 2,4,5-trifluorophenylacrylic acid is used to prepare the regulator, the change in surface properties or the change in the conjugated properties of the system caused by the reduction in the number of fluorine atoms leads to a change in the interaction between the regulator and the basic nickel carbonate precipitate, resulting in a decrease in the particle size uniformity of basic nickel carbonate and an increase in the impurity content.

[0080] As can be seen from Example 1 and Comparative Example 4, when 2-amino-1-butanol is used to prepare the regulator, the regulator molecule lacks a sterically hindered tert-butyl group, which leads to changes in its steric hindrance effect and surface properties. This results in an increased ability to hinder the migration of impurity ions into the basic nickel carbonate precipitate, leading to an increase in the impurity content of the basic nickel carbonate.

[0081] As can be seen from Example 1 and Comparative Examples 5-6, when maleic acid or tetracosenoic acid is used to prepare the regulator, the length of the long aliphatic chain in the regulator molecular chain changes, resulting in changes in the hydrophobic effect and steric hindrance effect, which in turn causes changes in the surface properties and adsorption capacity of the regulator, resulting in poor particle size uniformity of basic nickel carbonate and increased impurity content.

[0082] As can be seen from Example 1 and Comparative Examples 7 and 9-10, when a mixture of (S)-tert-leucine, sodium 2-(trifluoromethyl)acrylate and sodium 9-octadecenoate is used, or when sodium citrate and disodium ethylenediaminetetraacetate are used, the particle size uniformity of the prepared basic nickel carbonate is poor and the impurity content is high. This further proves that the regulator used in this invention can significantly improve the particle size uniformity of basic nickel carbonate and reduce the impurity content.

[0083] As can be seen from Example 1 and Comparative Example 8, after the hydroxyl group in the regulator molecule of Example 1 reacts with succinic anhydride to attach to the carboxyl group, the number of carboxyl salts in the molecular chain increases, the hydroxyl group disappears, the particle size uniformity of basic nickel carbonate deteriorates, and the impurity content increases. This indicates that the hydroxyl group in the regulator molecule can also be adsorbed on the surface of basic nickel carbonate precipitate through hydrogen bonding and other interactions, thereby improving the surface properties of the regulator and playing a role in improving the particle size uniformity of basic nickel carbonate and reducing the impurity content.

[0084] It should be noted that, in this document, the terms "comprising," "including," and any other variations are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Specific examples have been used in this document to illustrate the principles and implementation methods of the present invention. These examples are merely for the purpose of helping to understand the method and core ideas of the present invention. The above descriptions are only preferred embodiments of the present invention. It should be pointed out that, due to the limitations of written expression and the objective existence of infinite specific structures, those skilled in the art can make several improvements, modifications, or variations without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, variations, or combinations, or the direct application of the concept and technical solution of the present invention to other situations without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A method for preparing basic nickel carbonate, characterized in that, Includes the following steps: Nickel salt, carbonate, and regulator are subjected to a precipitation reaction, and after purification, basic nickel carbonate is obtained. The regulator is prepared as follows: S-tert-leucine alcohol and 2-trifluoromethylacrylic acid are subjected to a Michael addition reaction to obtain an addition product. The addition product is then subjected to a Michael addition reaction with 9-octadecenoic acid to obtain an intermediate. The intermediate is then subjected to a salt formation reaction with sodium hydroxide to obtain the regulator. The molar ratio of S-tert-leucine alcohol, 2-trifluoromethylacrylic acid, and 9-octadecenoic acid is 1:1:1, and the molar ratio of the intermediate to sodium hydroxide is... The ratio is 1:3; the volume ratio of nickel salt solution to carbonate solution in the precipitation reaction is 100~150:90~120, the amount of regulator used per 100L nickel salt solution is 100~120g, the temperature is 50~58℃, and the time is 2.5~3.2h; the Michael addition reaction of S-tert-leucine and 2-trifluoromethylacrylic acid is carried out at a temperature of 35~40℃ for a time of 12~15h; the Michael addition reaction of the addition product and 9-octadecenoic acid is carried out at a temperature of 60~70℃ for a time of 18~24h.

2. The method for preparing basic nickel carbonate according to claim 1, characterized in that, The nickel salt is one or any combination of nickel sulfate, nickel sulfate hydrate, nickel chloride, and nickel chloride hydrate.

3. The method for preparing basic nickel carbonate according to claim 1, characterized in that, The carbonate is ammonium carbonate.

4. The method for preparing basic nickel carbonate according to claim 1, characterized in that, The precipitation reaction is performed as follows: a nickel salt solution, a carbonate solution, and a regulator are stirred and mixed. The concentration of the nickel salt solution is 2.0~2.4 mol / L, and the concentration of the carbonate solution is 2.5~2.9 mol / L.

5. The method for preparing basic nickel carbonate according to claim 4, characterized in that, The stirring rate during the precipitation reaction is 300~400 r / min.

6. The method for preparing basic nickel carbonate according to claim 1, characterized in that, The purification method is as follows: the system after precipitation reaction is subjected to solid-liquid separation to obtain crude basic nickel carbonate, and then the crude basic nickel carbonate is washed and dried to obtain basic nickel carbonate.

7. The method for preparing basic nickel carbonate according to claim 6, characterized in that, The washing process involves first washing the crude basic nickel carbonate with water, then washing it with a 0.4 mol / L calcium chloride solution, followed by a third washing with water. Finally, the system after the three washings is centrifuged and filtered to obtain wet basic nickel carbonate.

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