High-precision aluminum hydroxide wet purification process

Abstract

The invention provides a high-precision aluminum hydroxide wet purification process, and relates to the technical field of aluminum hydroxide production and manufacturing, and the high-precision aluminum hydroxide wet purification process comprises the following steps: step S1, crushing and grinding raw materials to obtain fine particles suitable for subsequent dissolution; s2, the pretreated raw materials are subjected to a leaching reaction in a solvent, an aluminum compound in the raw materials is fully dissolved into soluble aluminum salt, and meanwhile uniform mixing and stable temperature are maintained; the process is matched with crushing and solvent processing to optimize subsequent leaching reaction conditions, so that an aluminum compound can be more sufficiently dissolved into soluble aluminum salt, the reaction efficiency and uniformity are improved, meanwhile, the impurity removal process can effectively remove various types of impurity ions, and the purity of the product is improved. And accurate control of cooling crystallization is matched to ensure that the generated aluminum hydroxide crystals are uniform in size and excellent in quality, the stability and consistency among batches of products are improved, waste is reduced, and the yield is improved.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum hydroxide production and manufacturing, and in particular to a high-precision aluminum hydroxide wet purification process. Background Art

[0002] As an important inorganic material, aluminum hydroxide is widely used in ceramics, chemicals, medicine, electronics and other fields. Traditionally, the purification process of aluminum hydroxide mainly relies on the hydrometallurgical process, which extracts high-purity aluminum hydroxide from raw materials by chemical dissolution and recrystallization. However, as downstream applications continue to increase product purity and performance requirements, the traditional hydrometallurgical purification process has gradually exposed many limitations.

[0003] Although the existing technology has achieved the purification of aluminum hydroxide to a certain extent, there are still some significant problems. First, the pretreatment steps in the traditional process are often not fine enough, and the material particle size is large, resulting in low efficiency of the subsequent leaching reaction, affecting the overall production efficiency. Secondly, in the process of impurity removal, most processes only rely on a single precipitation method or simple filtration means, which cannot completely remove various types of impurity ions, especially trace metal ions and organic matter, thereby reducing the purity of the final product. Summary of the invention

[0004] The present invention aims to solve the shortcomings existing in the background technology, provide a high-precision aluminum hydroxide wet purification process, adopt optimized pretreatment and leaching and precipitation processes to prevent impurities in the raw materials from causing lower production efficiency, and at the same time adopt an optimized impurity removal process to provide a good and comprehensive impurity removal effect to avoid a reduction in the purity of the finished product.

[0005] To achieve the above object, the present invention provides the following technical solution, a high-precision aluminum hydroxide wet purification process, comprising the following steps: Step S1: pre-processing the raw material by crushing and grinding to obtain fine particles suitable for subsequent dissolution; Step S2: subjecting the pretreated raw material to a leaching reaction in a solvent so that the aluminum compound therein is fully dissolved into a soluble aluminum salt while maintaining uniform mixing and a stable temperature; Step S3: removing impurity ions in the solution, adding a precipitant to cause calcium and magnesium ions to form insoluble compounds and precipitate, and further purifying the solution by using adsorption, ion exchange and membrane separation technology; Step S4: Prompt pure aluminum hydroxide crystals to precipitate from the solution by cooling crystallization or evaporation concentration, while controlling the cooling rate and supersaturation to ensure the quality of the crystals; Step S5: finely separating the precipitated crystals to further ensure the purity of the product; Step S6: Low-temperature drying and separation of the aluminum hydroxide crystals are performed, and classification and packaging are performed according to particle size requirements.

[0006] Furthermore, the step S1 also includes the following specific steps: Step S11: crushing the bauxite or secondary aluminum resource material until the diameter is less than 20 mm; Step S12: Grind the crushed material until the material can pass through a 200-mesh sieve.

[0007] Furthermore, the solvent in step S2 is any one of a dilute sulfuric acid solution and a caustic soda solution having a pH value between 8 and 10.

[0008] Furthermore, the step S2 also includes the following specific steps: Step S21: mixing the ground raw material with a solvent and leaching the raw material to fully dissolve the aluminum compound into a soluble aluminum salt; Step S22: using a stirrer to continuously stir and mix, and continuously heating the solution to control the leaching time to be between 2-4 hours.

[0009] Furthermore, the step S3 also includes the following specific steps: Step S31: adding 10-15 wt% of lime milk in a ratio of 1:1.2 to the total amount of calcium and magnesium ions, so that the calcium and magnesium ions form insoluble carbonates or sulfates and then precipitate; Step S32: directing the solution through a filling density of 0.5-0.8 g / cm 3 The activated carbon is used to control the flow rate within 0.5-2 m / h to remove organic matter and other impurity ions in the solution; Step S33: filtering the solution under high pressure using a filter membrane, wherein the filter membrane is any one of a nanofiltration membrane with a molecular weight cutoff of 200-500 Da and a reverse osmosis membrane with an operating pressure of 10-20 bar.

[0010] Furthermore, in step S33, a multi-stage filtration technology is used, where larger particle impurities are first filtered through a coarse filter membrane and then filtered through different types in sequence.

[0011] Furthermore, the step S4 also includes the following specific steps: Step S41: Cooling the solution at a cooling rate of 3°C / h to form cooling crystals through the cooling effect. After the initial solution temperature drops to 50°C, the temperature begins to drop slowly at a rate of 2°C per hour until it drops to the target temperature. Step S42: During the cooling and crystallization process, the supersaturation of the solution is adjusted to ensure that its value is between 1.05-1.15 to promote uniform crystal formation.

[0012] Furthermore, the step S5 also includes the following specific steps: Step S51: using a self-cleaning continuous filter press in combination with an automatic control system to achieve efficient solid-liquid separation, wherein the filtration rate is 0.5-2 m³ / m²·h; Step S52: fine particles are separated more finely using a high-speed centrifuge with a rotation speed of 3000-5000 rpm to ensure separation effect and product quality.

[0013] Furthermore, the step S6 also includes the following specific steps: Step S61: using a fluidized bed dryer to dry the material, wherein the temperature of the fluidized bed dryer cannot exceed 120°C, and the air humidity is controlled at 30%-60%; Step S62: Use a vibrating screen to screen the finished particles according to particle size to ensure the product particle size.

[0014] The present invention provides a high-precision aluminum hydroxide wet purification process, which has the following beneficial effects: The advantages of the present invention are that the subsequent leaching reaction conditions are optimized by combining crushing and solvent processing, so that the aluminum compound can be more fully dissolved into a soluble aluminum salt, thereby improving the reaction efficiency and uniformity. At the same time, the impurity removal process can effectively remove various types of impurity ions, and cooperate with precise control of cooling crystallization to ensure that the generated aluminum hydroxide crystals are uniform in size and of excellent quality, thereby improving the batch-to-batch stability and consistency of the product, reducing waste and increasing the yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the process flow of the present invention.

[0016] Figure 2 It is a raw material processing flow chart of the present invention. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0018] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0019] The embodiment of the present application provides a high-precision aluminum hydroxide wet purification process, which can achieve the optimization of subsequent leaching reaction conditions by coordinating crushing and solvent processing, so that aluminum compounds can be more fully dissolved into soluble aluminum salts, improve reaction efficiency and uniformity, and at the same time, the impurity removal process can effectively remove various types of impurity ions, and cooperate with precise control of cooling crystallization to ensure that the generated aluminum hydroxide crystals are uniform in size and of good quality, improve the batch-to-batch stability and consistency of the product, reduce waste and increase yield. The high-precision aluminum hydroxide wet purification process is described in detail below. It should be noted that the description order of the following embodiments is not intended to limit the preferred order of the embodiments.

[0020] The present application is described in detail below in conjunction with the accompanying drawings and specific implementation methods. Figure 1-2 In this embodiment, a high-precision aluminum hydroxide wet purification process is provided, comprising the following steps: Step S1: pre-processing the raw material by crushing and grinding to obtain fine particles suitable for subsequent dissolution; Step S2: subjecting the pretreated raw material to a leaching reaction in a solvent so that the aluminum compound therein is fully dissolved into a soluble aluminum salt while maintaining uniform mixing and a stable temperature; Step S3: removing impurity ions in the solution, adding a precipitant to cause calcium and magnesium ions to form insoluble compounds and precipitate, and further purifying the solution by using adsorption, ion exchange and membrane separation technology; Step S4: Prompt pure aluminum hydroxide crystals to precipitate from the solution by cooling crystallization or evaporation concentration, while controlling the cooling rate and supersaturation to ensure the quality of the crystals; Step S5: finely separating the precipitated crystals to further ensure the purity of the product; Step S6: Low-temperature drying and separation of the aluminum hydroxide crystals are performed, and classification and packaging are performed according to particle size requirements.

[0021] Wherein, the step S1 also includes the following specific steps: Step S11: crushing the bauxite or secondary aluminum resource material until the diameter is less than 20 mm; Step S12: Grind the crushed material until the material can pass through a 200-mesh sieve.

[0022] During processing, the fine particles increase the contact area with the solvent, thereby improving the efficiency of the subsequent dissolution reaction. At the same time, the consistent particle size of the material passing through the 200-mesh screen helps to achieve more uniform dispersion and reaction during the leaching process.

[0023] Wherein, the solvent in step S2 is any one of a dilute sulfuric acid solution and a caustic soda solution having a pH value between 8 and 10.

[0024] Wherein, the step S2 also includes the following specific steps: Step S21: mixing the ground raw material with a solvent and leaching the raw material to fully dissolve the aluminum compound into a soluble aluminum salt; Step S22: using a stirrer to continuously stir and mix, and continuously heating the solution to control the leaching time to be between 2-4 hours.

[0025] Wherein, the step S3 also includes the following specific steps: Step S31: adding 10-15 wt% of lime milk in a ratio of 1:1.2 to the total amount of calcium and magnesium ions, so that the calcium and magnesium ions form insoluble carbonates or sulfates and then precipitate; Step S32: directing the solution through a filling density of 0.5-0.8 g / cm 3 The activated carbon is used to control the flow rate within 0.5-2 m / h to remove organic matter and other impurity ions in the solution; Step S33: filtering the solution under high pressure using a filter membrane, wherein the filter membrane is any one of a nanofiltration membrane with a molecular weight cutoff of 200-500 Da and a reverse osmosis membrane with an operating pressure of 10-20 bar.

[0026] Wherein, in step S33, a multi-stage filtration technology is adopted, and larger particle impurities are first filtered through a coarse filter membrane, and then filtered through different types in sequence.

[0027] During the processing, various types of impurity ions are effectively removed through multi-step treatment, thereby improving product purity. The use of physical adsorption and membrane separation technology avoids excessive use of chemical reagents and reduces environmental pollution. Multi-stage filtration technology reduces the impurity content in the final solution and improves product quality.

[0028] Wherein, the step S4 also includes the following specific steps: Step S41: Cooling the solution at a cooling rate of 3°C / h to form cooling crystals through the cooling effect. After the initial solution temperature drops to 50°C, the temperature begins to drop slowly at a rate of 2°C per hour until it drops to the target temperature. Step S42: During the cooling and crystallization process, the supersaturation of the solution is adjusted to ensure that its value is between 1.05-1.15 to promote uniform crystal formation.

[0029] During the processing, the cooling rate and supersaturation are precisely controlled to ensure that the generated crystals are of uniform size and excellent quality. A reasonable cooling strategy is used to increase the yield of crystal precipitation and reduce waste. The control of the supersaturation factor ensures the consistency of crystal growth and improves the batch-to-batch stability of the product.

[0030] Wherein, the step S5 also includes the following specific steps: Step S51: using a self-cleaning continuous filter press in combination with an automatic control system to achieve efficient solid-liquid separation, wherein the filtration rate is 0.5-2 m³ / m²·h; Step S52: fine particles are separated more finely using a high-speed centrifuge with a rotation speed of 3000-5000 rpm to ensure separation effect and product quality.

[0031] In the processing process, the above steps can achieve the combined use of self-cleaning filter press and high-speed centrifuge, realize efficient solid-liquid separation, reduce separation time, and use automatic control system to ensure the stability and repeatability of the separation process, reducing the risk of manual intervention.

[0032] Wherein, the step S6 also includes the following specific steps: Step S61: using a fluidized bed dryer to dry the material, wherein the temperature of the fluidized bed dryer cannot exceed 120°C, and the air humidity is controlled at 30%-60%; Step S62: Use a vibrating screen to screen the finished particles according to particle size to ensure the product particle size.

[0033] During the processing, the above process can utilize low-temperature drying to avoid the influence of high temperature on the product structure, maintain the activity of aluminum hydroxide crystals, and at the same time control the air humidity of the fluidized bed dryer to prevent material adhesion and ensure the uniformity of drying.

[0034] Utilizing the above scheme, the purification process can achieve multi-stage purification by adding lime milk, activated carbon adsorption, anion exchange resin, and a combination of nanofiltration membrane or reverse osmosis membrane, and adopt precise cooling rate and supersaturation factor control, combined with cooling crystallization or evaporation concentration methods to promote crystal precipitation, thereby ensuring that the generated aluminum hydroxide crystals are uniform in size and excellent in quality, improving the batch-to-batch stability and consistency of the product, reducing waste and increasing yield.

[0035] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0036] The above is a detailed introduction to a high-precision aluminum hydroxide wet purification process provided in the embodiments of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solution and core idea of ​​the present application; ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the present application.

Claims

1. A high-precision aluminum hydroxide wet purification process, characterized in that: The steps include: Step S1: pre-processing the raw material by crushing and grinding to obtain fine particles suitable for subsequent dissolution; Step S2: subjecting the pretreated raw material to a leaching reaction in a solvent so that the aluminum compound therein is fully dissolved into a soluble aluminum salt while maintaining uniform mixing and a stable temperature; Step S3: removing impurity ions in the solution, adding a precipitant to cause calcium and magnesium ions to form insoluble compounds and precipitate, and further purifying the solution by using adsorption, ion exchange and membrane separation technology; Step S4: Prompt pure aluminum hydroxide crystals to precipitate from the solution by cooling crystallization or evaporation concentration, while controlling the cooling rate and supersaturation to ensure the quality of the crystals; Step S5: finely separating the precipitated crystals to further ensure the purity of the product; Step S6: Low-temperature drying and separation of the aluminum hydroxide crystals are performed, and classification and packaging are performed according to particle size requirements.

2. The high-precision aluminum hydroxide wet purification process according to claim 1, characterized in that: The step S1 also includes the following specific steps: Step S11: crushing the bauxite or secondary aluminum resource material until the diameter is less than 20 mm; Step S12: Grind the crushed material until the material can pass through a 200-mesh sieve.

3. The high-precision aluminum hydroxide wet purification process according to claim 2, characterized in that: The solvent in step S2 is any one of a dilute sulfuric acid solution and a caustic soda solution having a pH value between 8 and 10.

4. The high-precision aluminum hydroxide wet purification process according to claim 1, characterized in that: The step S2 also includes the following specific steps: Step S21: mixing the ground raw material with a solvent and leaching the raw material to fully dissolve the aluminum compound into a soluble aluminum salt; Step S22: using a stirrer to continuously stir and mix, and continuously heating the solution to control the leaching time to be between 2-4 hours.

5. The high-precision aluminum hydroxide wet purification process according to claim 1, characterized in that: The step S3 also includes the following specific steps: Step S31: adding 10-15 wt% of lime milk in a ratio of 1:1.2 to the total amount of calcium and magnesium ions, so that the calcium and magnesium ions form insoluble carbonates or sulfates and then precipitate; Step S32: directing the solution through a filling density of 0.5-0.8 g / cm 3 The activated carbon is used to control the flow rate within 0.5-2 m / h to remove organic matter and other impurity ions in the solution; Step S33: filtering the solution under high pressure using a filter membrane, wherein the filter membrane is any one of a nanofiltration membrane with a molecular weight cutoff of 200-500 Da and a reverse osmosis membrane with an operating pressure of 10-20 bar.

6. The high-precision aluminum hydroxide wet purification process according to claim 5, characterized in that: In the step S33, a multi-stage filtration technology is used, where larger particles of impurities are first filtered through a coarse filter membrane, and then filtered through different types in sequence.

7. The high-precision aluminum hydroxide wet purification process according to claim 1, characterized in that: The step S4 also includes the following specific steps: Step S41: Cooling the solution at a cooling rate of 3°C / h to form cooling crystals through the cooling effect. After the initial solution temperature drops to 50°C, the temperature begins to drop slowly at a rate of 2°C per hour until it drops to the target temperature. Step S42: During the cooling and crystallization process, the supersaturation of the solution is adjusted to ensure that its value is between 1.05-1.15 to promote uniform crystal formation.

8. The high-precision aluminum hydroxide wet purification process according to claim 1, characterized in that: The step S5 also includes the following specific steps: Step S51: using a self-cleaning continuous filter press in combination with an automatic control system to achieve efficient solid-liquid separation, wherein the filtration rate is 0.5-2 m³ / m²·h; Step S52: fine particles are separated more finely using a high-speed centrifuge with a rotation speed of 3000-5000 rpm to ensure separation effect and product quality.

9. The high-precision aluminum hydroxide wet purification process according to claim 1, characterized in that: The step S6 also includes the following specific steps: Step S61: using a fluidized bed dryer to dry the material, wherein the temperature of the fluidized bed dryer cannot exceed 120°C, and the air humidity is controlled at 30%-60%; Step S62: Use a vibrating screen to screen the finished particles according to particle size to ensure the product particle size.

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