An ultrasonic-coupled chemical purification method for high-purity optical-grade calcite raw materials

Abstract

This invention belongs to the field of mineral purification technology, specifically relating to an ultrasonic-coupled chemical purification method for high-purity optical-grade calcite raw materials. The method includes: 1) taking high-whiteness calcite concentrate and performing high-intensity magnetic separation to obtain pretreated material; 2) mixing the pretreated material with water and ultrasonically cleaning to obtain cleaned material; 3) mixing the cleaned material with a chemical washing solution and separating the resulting material to obtain iron-removed material; the chemical washing solution is mainly composed of a mixture of chelating agent, dispersant, and water; 4) rinsing the iron-removed material with water to obtain rinsed material; 5) drying the rinsed material to obtain the final product. This method achieves gradient and comprehensive iron removal and purification through dual coupling of physical high-intensity magnetic separation and chemical chelation iron removal, significantly improving iron removal efficiency and product purity. The resulting calcite has an Fe2O3 content ≤3ppm, a CaCO3 content ≥99.99%, a whiteness ≥95, and a particle surface cleanliness ≥Class 1000, meeting the requirements for optical-grade use. The process is feasible, environmentally friendly, and suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of mineral purification technology, specifically relating to an ultrasonic-coupled chemical purification method for optical-grade high-purity calcite raw materials. Background Technology

[0002] Calcite is a calcium carbonate mineral. As an important non-metallic mineral raw material, it is widely used in optical fields such as optical glass, optical lenses, and high-end display panels due to its high whiteness, high purity, good optical properties, and chemical stability. Optical-grade calcite has strong birefringence. As a raw material for optical devices, it has stringent requirements for Fe2O3 content, CaCO3 purity, and whiteness. However, the magnetic iron-bearing minerals (such as hematite and limonite) contained in calcite and the trace iron impurities attached to its surface are the core bottlenecks that prevent it from meeting optical-grade standards.

[0003] Traditional calcite purification and whiteness enhancement processes are primarily manual, supplemented by simple mechanical treatments. These mainly include manual sorting, scrubbing, and chemical bleaching. Manual sorting is the most primitive method, requiring no complex equipment but relying solely on human judgment. Its efficiency is extremely low, highly subjective, and makes it difficult to guarantee the uniformity of whiteness after purification. Scrubbing utilizes friction and collision between mineral particles or between mineral particles and machinery for purification. It can only remove loose impurities from the ore surface and cannot remove metal ions trapped within the ore, thus limiting its whiteness enhancement. Chemical bleaching involves reacting chemical agents with coloring impurities in the mineral (mainly iron, titanium, and organic matter), converting them into soluble or easily washable substances, thereby improving mineral whiteness. However, it can only remove some easily reacting pigment ions, and traditional processes often use general-purpose bleaching agents, which can lead to incomplete reactions between the agent and ore components, resulting in secondary pollution and ultimately a decrease in calcite whiteness and impaired performance. While traditional chemical washing methods can remove iron, they often introduce a large amount of organic reagent residues and micro-nano-sized byproduct particles, leading to defects such as scattering and optical distortion when calcite is processed into optical devices.

[0004] The aforementioned traditional methods are insufficient for precisely controlling the purification and whiteness improvement of calcite, failing to meet the demands of large-scale, high-quality production in modern industry. Therefore, developing efficient, precise, and environmentally friendly calcite purification and whiteness enhancement processes has become an inevitable trend in the industry. Summary of the Invention

[0005] The purpose of this invention is to provide an ultrasonic-coupled chemical purification method for optical-grade high-purity calcite raw materials, achieving gradient and all-round iron removal purification, significantly improving iron removal efficiency and calcite product purity.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An ultrasonic-coupled chemical purification method for high-purity optical-grade calcite raw materials includes the following steps: 1) Take high-whiteness calcite concentrate and perform high-intensity magnetic separation to remove iron, and obtain pretreated material; 2) Mix the obtained pretreated material with water and ultrasonically clean it to obtain the cleaned material; 3) Mix the obtained cleaning material with the chemical cleaning solution, adjust the pH of the system to 5.0-6.5, react for 10-60 minutes, and then separate the iron-removed material. The chemical cleaning solution is mainly composed of a mixture of chelating agent, dispersant and water; the mass ratio of chelating agent, dispersant and water is 0.5-2:0.1-0.5:100; the chelating agent is any one or a combination of tetrasodium iminodisuccinate, tetrasodium glutamate diacetate and trisodium citrate. 4) Rinse the obtained iron-removed material with water to obtain rinsed material; 5) Dry the obtained rinsed material to obtain the final product.

[0007] In step 1), the high-whiteness calcite concentrate meets the following requirements: Fe2O3 mass content ≤ 20ppm, CaCO3 mass content ≥ 98.5%, and whiteness ≥ 90.

[0008] Furthermore, the particle size of the high-whiteness calcite concentrate is 10-120 mesh.

[0009] More preferably, the high-whiteness calcite concentrate meets the following requirements: Fe2O3 mass content 10-20ppm, CaCO3 mass content ≥98.5%, and whiteness 90-93.

[0010] Furthermore, in step 1), the magnetic induction intensity of the high-intensity magnetic separation iron removal process is 15000-22000 Gauss.

[0011] In step 1), the high-intensity magnetic separation iron removal process uses a high-gradient magnetic separator to perform dry two-stage magnetic separation on the high-white calcite concentrate under a magnetic induction intensity of 15000-22000 Gauss.

[0012] The purpose of high-intensity magnetic separation for iron removal is to initially remove magnetic iron-containing impurities from the concentrate.

[0013] In step 2), the ratio of pretreated material to water is 1:2-6.

[0014] In this invention, the material-liquid ratio is always a mass-volume ratio (kg:L).

[0015] In step 2), the frequency of the ultrasound is 28-40kHz, the temperature is 40-55℃, and the time is 20-40min.

[0016] The purpose of ultrasonic cleaning is to remove impurities and loose iron-containing deposits adhering to the surface of materials.

[0017] In step 3), the ratio of the cleaning material to the chemical cleaning solution is 1:3-10.

[0018] Furthermore, in the chemical washing solution, when the chelating agent is any two of tetrasodium iminodisuccinate, tetrasodium glutamate diacetate, and trisodium citrate, the mass ratio is 1-2:1; when the chelating agent is a combination of tetrasodium iminodisuccinate, tetrasodium glutamate diacetate, and trisodium citrate, the mass percentage of each component is 10%-80%.

[0019] In step 3), the dispersant is any one or a combination of sodium polyacrylate and sodium polymaleate.

[0020] Furthermore, the preparation method of the chemical cleaning solution is as follows: first, the dispersant is mixed with water and stirred until completely dissolved, then the chelating agent is added and stirred until evenly dispersed.

[0021] In step 3), the pH value of the system is adjusted using a citric acid solution with a mass concentration of 5%-10% or an acetic acid solution with a mass concentration of 5%-8%.

[0022] In step 3), the pH of the system is adjusted to 5.0-6.5. If the pH is too low, the calcite surface will be acid-dissolved, damaging the structure and causing defects. If the pH is too high, the complexing ability of the chelating agent on iron ions will be sharply reduced, and the Fe2O3 content in the final product will not meet the requirements.

[0023] Furthermore, in step 4), rinsing refers to rinsing until the pH value of the system is 6.8-7.5.

[0024] In step 4), the rinsing is a three-stage countercurrent pure water rinsing, with a material-to-liquid ratio of 1:2-4 for each stage; the parameters for each stage are as follows: First-stage rinsing: The system pH is 6.0-7.0, free Fe... 3+ ≤5ppm, pesticide residue ≤100ppm; Secondary rinsing: The system pH is 6.5-7.2, free Fe... 3+ ≤1ppm, pesticide residue ≤10ppm; Three-stage rinsing: The system pH is 6.8-7.5, free Fe... 3+ ≤0.1ppm, particle surface cleanliness ≥Class1000.

[0025] In this invention, a particle surface cleanliness rating of Class 1000 means that the number of dust particles with a diameter ≥ 0.5 μm is ≤ 1000 per square foot of surface. A particle surface cleanliness rating ≥ Class 1000 means that the particle surface cleanliness is not lower than Class 1000 (thousand-class). In the particle surface cleanliness rating system, the smaller the number after Class, the higher the particle surface cleanliness.

[0026] In step 5), the drying temperature is 120-160℃, and the material is dried until the moisture content is ≤0.1%.

[0027] The ultrasonic-coupled chemical purification method for high-purity optical-grade calcite raw materials of the present invention adopts a dual iron removal coupling method of physical high-intensity magnetic separation and chemical chelation iron removal, which breaks through the limitation of single iron removal process that is difficult to achieve high-precision white purification, and realizes gradient and all-round iron removal purification.

[0028] Among them, physical high-intensity magnetic separation for iron removal serves as a pretreatment that can quickly and efficiently remove most of the magnetic iron-containing impurities in the raw materials, such as limonite and hematite, completing the initial coarse iron removal and laying the foundation for subsequent fine purification. At the same time, it avoids large iron particles scratching calcite particles and obscuring surface impurities, thus improving the efficiency of subsequent processes.

[0029] Ultrasonic cleaning combined with chemical chelation for iron removal works in two ways. First, ultrasound removes loose iron-containing deposits from the material surface. The cavitation effect of ultrasound generates microjets and localized high pressure on the surface of calcite particles. After removing the loose deposits, the dispersants and chelating agents in the subsequent chemical cleaning solution can quickly penetrate to the calcite surface, microcracks, and edges of lattice defects, improving the complexation efficiency. Second, environmentally friendly chelating agents are used to specifically complex trace iron impurities remaining on and inside the material surface. Within a safe, weakly acidic pH range of 5.0-6.5, ultra-deep iron removal is achieved in a very short time, while avoiding the acid dissolution loss of calcium carbonate.

[0030] The synergistic effect of the dual iron removal modes not only significantly improves iron removal efficiency, reduces the amount of chemical reagents used, and lowers production costs, but also effectively ensures the high whiteness and high purity of calcite raw materials, greatly reduces reagent residues and particulate adsorption, and successfully prepares high-purity calcite raw materials that meet the requirements for optical-grade use. This solves the technical pain points of insufficient purification precision and substandard whiteness in traditional single iron removal processes, and the process is highly feasible and suitable for industrial production.

[0031] This invention provides an ultrasonic-coupled chemical purification method for optical-grade high-purity calcite raw materials, which significantly improves iron removal efficiency and product purity. The resulting calcite has a Fe2O3 content ≤3ppm, a CaCO3 content ≥99.99%, a whiteness ≥95, and a particle surface cleanliness ≥Class 1000, meeting the requirements for optical-grade high-purity raw materials. The process is feasible, environmentally friendly, and suitable for industrial production. Detailed Implementation

[0032] The present invention will be further described below with reference to specific embodiments.

[0033] In specific embodiments, the preparation method of the chemical cleaning solution is as follows: first, the dispersant and water are stirred and mixed until completely dissolved, then the chelating agent is added, and the mixture is stirred again until it is evenly dispersed, thus obtaining the solution.

[0034] In a specific embodiment, the molecular weight of the sodium polyacrylate used is 2000-5000.

[0035] In the specific implementation, the pH value of the system was adjusted by adding the components dropwise.

[0036] Example 1

[0037] The ultrasonic-coupled chemical purification method for high-purity optical-grade calcite raw materials in this embodiment includes the following steps: 1) Take high-whiteness calcite concentrate and use a high-gradient magnetic separator to perform dry two-stage magnetic separation under a magnetic induction intensity of 15000 Gauss to obtain pretreated material; The high-whiteness calcite concentrate meets the following requirements: average feed particle size of 50 mesh, Fe2O3 mass content of 15ppm, CaCO3 mass content of 98.5%, and whiteness of 90. 2) Mix the obtained pretreated material with water at a material-to-liquid ratio of 1:4, and ultrasonically clean it for 30 minutes at 48℃ and 35kHz. Filter the cleaned material. 3) The obtained cleaning material and chemical washing solution were mixed in a reaction vessel at a material-to-liquid ratio of 1:4. The pH of the system was adjusted to 5.8 using an 8% acetic acid solution. After reacting for 30 minutes under stirring, the iron-removed material was separated. The chemical cleaning solution is prepared by mixing a chelating agent, a dispersant, and water; the mass ratio of the chelating agent, dispersant, and water is 1.2:0.3:100; the chelating agent is tetrasodium iminodisuccinate; the dispersant is sodium polyacrylate. 4) The obtained iron-removed material is rinsed with three-stage countercurrent pure water, with a material-to-liquid ratio of 1:3 for each stage, to obtain the rinsed material; the parameters for each stage are as follows: First rinse: System pH=6.5, free Fe 3+ ≤5ppm, pesticide residue ≤100ppm; Secondary rinsing: System pH=6.8, free Fe 3+ ≤1ppm, pesticide residue ≤10ppm; Three-stage rinsing: System pH=7.2, free Fe 3+ ≤0.1ppm, particle surface cleanliness ≥Class 1000;

[0038] 5) The obtained rinsed material is dried at 140℃ until the moisture content is 0.08% to obtain high-purity material, which is calcite optical grade high-purity raw material.

[0039] The obtained optical-grade high-purity calcite raw material was tested and found to have a Fe2O3 content of 2.3 ppm, a CaCO3 content of 99.992%, a whiteness of 96.2, and a particle surface cleanliness of Class 800, which meets the requirements for optical-grade high-purity raw materials.

[0040] Example 2

[0041] The ultrasonic-coupled chemical purification method for high-purity optical-grade calcite raw materials in this embodiment includes the following steps: 1) Take high-whiteness calcite concentrate and use a high-gradient magnetic separator to perform dry two-stage magnetic separation under a magnetic induction intensity of 20,000 Gauss to obtain pretreated material; The high-whiteness calcite concentrate meets the following requirements: average feed particle size of 30 mesh, Fe2O3 mass content of 12ppm, CaCO3 mass content of 99%, and whiteness of 93. 2) Mix the obtained pretreated material with water at a material-to-liquid ratio of 1:2, and ultrasonically clean it for 20 minutes at 40℃ and 28kHz. Filter the cleaned material. 3) The obtained cleaning material and chemical cleaning solution are mixed in a reaction vessel at a material-to-liquid ratio of 1:3. The pH of the system is adjusted to 5.0 using a 5% citric acid solution. After reacting for 20 minutes under stirring, the iron-removed material is separated.

[0042] The chemical cleaning solution is prepared by mixing a chelating agent, a dispersant, and water; the mass ratio of the chelating agent, dispersant, and water is 0.5:0.1:100; the chelating agent is a mixture of tetrasodium glutamate diacetate and trisodium citrate in a mass ratio of 1:1; the dispersant is sodium polyacrylate.

[0043] 4) The obtained iron-removed material is rinsed with three-stage countercurrent pure water, with a material-to-liquid ratio of 1:2 for each stage, to obtain the rinsed material; the parameters for each stage are as follows: First rinse: System pH=6.0, free Fe 3+ ≤5ppm, pesticide residue ≤100ppm; Secondary rinsing: System pH=6.5, free Fe 3+ ≤1ppm, pesticide residue ≤10ppm; Three-stage rinsing: System pH=7.8, free Fe 3+ ≤0.1ppm, particle surface cleanliness ≥Class 1000; 5) The obtained rinsed material is dried at 120℃ until the moisture content is 0.09% to obtain high-purity material, which is calcite optical grade high-purity raw material.

[0044] The obtained optical-grade high-purity calcite raw material was tested and found to have a Fe2O3 content of 2.7 ppm, a CaCO3 content of 99.991%, a whiteness of 95.5, and a particle surface cleanliness of Class 900, which meets the requirements for optical-grade high-purity raw materials.

[0045] Example 3

[0046] The ultrasonic-coupled chemical purification method for high-purity optical-grade calcite raw materials in this embodiment includes the following steps: 1) Take high-whiteness calcite concentrate and use a high-gradient magnetic separator to perform dry two-stage magnetic separation under a magnetic induction intensity of 22000 Gauss to obtain pretreated material; The high-whiteness calcite concentrate meets the following requirements: average feed particle size of 100 mesh, Fe2O3 mass content of 18ppm, CaCO3 mass content of 98.5%, and whiteness of 90. 2) Mix the obtained pretreated material with water at a material-to-liquid ratio of 1:6, and ultrasonically clean it for 40 minutes at 55℃ and 40kHz. Filter the cleaned material. 3) The obtained cleaning material and chemical cleaning solution were mixed in a reaction vessel at a material-to-liquid ratio of 1:6. The pH of the system was adjusted to 6.5 using a 10% citric acid solution. After reacting for 40 minutes under stirring, the iron-removed material was separated. The chemical cleaning solution is prepared by mixing a chelating agent, a dispersant, and water; the mass ratio of the chelating agent, dispersant, and water is 2:0.5:100; the chelating agent is a mixture of tetrasodium glutamate diacetate, tetrasodium iminodisuccinate, and trisodium citrate, with the three components accounting for 30%, 30%, and 40% of their respective mass percentages; the dispersant is sodium polyacrylate. 4) The obtained iron-removed material is rinsed with three-stage countercurrent pure water, with a material-to-liquid ratio of 1:4 for each stage, to obtain the rinsed material; the parameters for each stage are as follows: First rinse: System pH=7.0, free Fe 3+ ≤5ppm, pesticide residue ≤100ppm; Secondary rinsing: System pH=7.2, free Fe 3+ ≤1ppm, pesticide residue ≤10ppm; Three-stage rinsing: System pH=7.5, free Fe 3+ ≤0.1ppm, particle surface cleanliness ≥Class 1000; 5) The obtained rinsed material is dried at 160℃ until the moisture content is 0.07% to obtain high-purity material, which is calcite optical grade high-purity raw material.

[0047] The obtained optical-grade high-purity calcite raw material was tested and found to have a Fe2O3 content of 2.1 ppm, a CaCO3 content of 99.993%, a whiteness of 96.5, and a particle surface cleanliness of Class 930, which meets the requirements for optical-grade high-purity raw materials.

[0048] Example 4

[0049] The ultrasonic-coupled chemical purification method for high-purity optical-grade calcite raw materials in this embodiment includes the following steps: 1) Take high-whiteness calcite concentrate and use a high-gradient magnetic separator to perform dry two-stage magnetic separation under a magnetic induction intensity of 18000 Gauss to obtain pretreated material; The calcite concentrate meets the following requirements: average feed particle size 80 mesh, Fe2O3 mass content 16ppm, CaCO3 mass content 98.7%, and whiteness 91. 2) Mix the obtained pretreated material with water at a material-to-liquid ratio of 1:5, and ultrasonically clean it for 35 minutes at 50℃ and 32kHz. Filter the cleaned material. 3) The obtained cleaning material and chemical washing solution were mixed in a reaction vessel at a material-to-liquid ratio of 1:5. The pH of the system was adjusted to 6.2 using a 7% acetic acid solution. After reacting for 50 minutes under stirring, the iron-removed material was separated. The chemical cleaning solution is prepared by mixing a chelating agent, a dispersant, and water; the mass ratio of the chelating agent, dispersant, and water is 1.2:0.3:100; the chelating agent is a mixture of tetrasodium glutamate diacetate and tetrasodium iminodisuccinate in a mass ratio of 2:1; the dispersant is sodium polymaleate. 4) The obtained iron-removed material is rinsed with three-stage countercurrent pure water. The material-to-liquid ratios for the first, second, and third stages are 1:2, 1:3, and 1:4, respectively, to obtain the rinsed material. The parameters for each stage are as follows: First rinse: System pH=6.3, free Fe 3+ ≤5ppm, pesticide residue ≤100ppm; Secondary rinsing: System pH=7.0, free Fe 3+ ≤1ppm, pesticide residue ≤10ppm; Three-stage rinsing: System pH=7.3, free Fe 3+ ≤0.1ppm, particle surface cleanliness ≥Class 1000; 5) The obtained rinsed material is dried at 150℃ until the moisture content is 0.08% to obtain high-purity material, which is calcite optical grade high-purity raw material.

[0050] The obtained optical-grade high-purity calcite raw material was tested and found to have a Fe2O3 content of 2.4 ppm, a CaCO3 content of 99.992%, a whiteness of 96.0, and a particle surface cleanliness of Class 1000, which meets the requirements for optical-grade high-purity raw materials.

[0051] Comparative Example 1

[0052] This comparative example uses the same calcite concentrate as in Example 1, without any purification treatment, and its performance indicators are as follows: The Fe2O3 content is 15ppm, the CaCO3 content is 98.5%, the whiteness is 90, the particle surface cleanliness Class is 5000, and there is no chemical residue. It does not meet the requirements for optical-grade high-purity raw materials.

[0053] Comparative Example 2

[0054] This comparative example uses the same calcite concentrate as Example 1, but employs only the high-gradient magnetic separation (step 1) and ultrasonic cleaning (step 2) of Example 1. The resulting material was tested and found to be: The Fe2O3 content is 8.6 ppm, the CaCO3 content is 99.2%, the whiteness is 93.8, the particle surface cleanliness is Class 3000, and there is no chemical residue, which does not meet the requirements for optical-grade high-purity raw materials.

[0055] Comparative Example 3

[0056] This comparative example uses the same calcite concentrate as Example 1, but employs only the high-gradient magnetic separation (step 1) and chemical cleaning (step 3) of Example 1. The resulting material was tested and found to be: The Fe2O3 content is 7.2 ppm, the CaCO3 content is 99.3%, the whiteness is 94.2, the particle surface cleanliness is Class 2500, and the reagent residue is 320 ppm, which does not meet the requirements for optical-grade high-purity raw materials.

[0057] Comparative Example 4

[0058] This comparative example uses the same calcite concentrate as Example 1, but employs only the high-gradient magnetic separation (step 1), ultrasonic cleaning (step 2), and chemical cleaning (step 3) processes as in Example 1. The resulting material was tested and found to be: The Fe2O3 content is 3.8 ppm, the CaCO3 content is 99.95%, the whiteness is 95.1, the particle surface cleanliness class is 1500, and the reagent residue is 86 ppm, which does not meet the requirements for optical-grade high-purity raw materials.

[0059] As can be seen from the comparison between Example 1 and Comparative Examples 1-4, the ultrasonic-coupled chemical purification method of the present invention can significantly reduce the Fe2O3 content in calcite, improve the purity and whiteness of CaCO3, reduce reagent residue, and improve the surface cleanliness of particles. The performance indicators of the obtained product meet the requirements of optical-grade high-purity raw materials. However, a single process or the lack of key steps cannot achieve the target effect.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent substitutions made using the content of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A method for ultrasonic-coupled chemical purification of optical-grade high-purity calcite raw material, characterized in that, Includes the following steps: 1) Take high-whiteness calcite concentrate and perform high-intensity magnetic separation to remove iron, and obtain pretreated material; 2) Mix the obtained pretreated material with water and ultrasonically clean it to obtain the cleaned material; 3) Mix the obtained cleaning material with the chemical cleaning solution, adjust the pH of the system to 5.0-6.5, react for 10-60 minutes, and then separate the iron-removed material. The chemical cleaning solution is mainly composed of a mixture of chelating agent, dispersant and water; the mass ratio of chelating agent, dispersant and water is 0.5-2:0.1-0.5:100; the chelating agent is any one or a combination of tetrasodium iminodisuccinate, tetrasodium glutamate diacetate and trisodium citrate. 4) Rinse the obtained iron-removed material with water to obtain rinsed material; 5) Dry the obtained rinsed material to obtain the final product.

2. The ultrasonic-coupled chemical purification method for optical-grade high-purity calcite raw materials according to claim 1, characterized in that, In step 1), the high-whiteness calcite concentrate meets the following requirements: Fe2O3 mass content ≤ 20ppm, CaCO3 mass content ≥ 98.5%, and whiteness ≥ 90.

3. The ultrasonic-coupled chemical purification method for high-purity optical-grade calcite raw materials according to claim 1, characterized in that, In step 1), the high-intensity magnetic separation iron removal process uses a high-gradient magnetic separator to perform dry two-stage magnetic separation on calcite concentrate under a magnetic induction intensity of 15000-22000 Gauss.

4. The ultrasonic-coupled chemical purification method for optical-grade high-purity calcite raw materials according to claim 1, characterized in that, In step 2), the frequency of the ultrasound is 28-40kHz, the temperature is 40-55℃, and the time is 20-40min.

5. The ultrasonic-coupled chemical purification method for high-purity optical-grade calcite raw materials according to claim 1, characterized in that, In step 3), the ratio of the cleaning material to the chemical cleaning solution is 1:3-10.

6. The ultrasonic-coupled chemical purification method for high-purity optical-grade calcite raw materials according to claim 1, characterized in that, In the chemical washing solution, when the chelating agent is any two of tetrasodium iminodisuccinate, tetrasodium glutamate diacetate, and trisodium citrate, the mass ratio is 1-2:1; when the chelating agent is a combination of tetrasodium iminodisuccinate, tetrasodium glutamate diacetate, and trisodium citrate, the mass percentage of each component is 10%-80%.

7. The ultrasonic-coupled chemical purification method for high-purity optical-grade calcite raw materials according to claim 1, characterized in that, In step 3), the dispersant is any one or a combination of sodium polyacrylate and sodium polymaleate.

8. The ultrasonic-coupled chemical purification method for high-purity optical-grade calcite raw materials according to claim 1, characterized in that, In step 3), the pH value of the system is adjusted using a citric acid solution with a mass concentration of 5%-10% or an acetic acid solution with a mass concentration of 5%-8%.

9. The ultrasonic-coupled chemical purification method for high-purity optical-grade calcite raw materials according to claim 1, characterized in that, In step 4), the rinsing is a three-stage countercurrent pure water rinsing, with a material-to-liquid ratio of 1:2-4 for each stage; the parameters for each stage are as follows: First-stage rinsing: The system pH is 6.0-7.0, free Fe... 3+ ≤5ppm, pesticide residue ≤100ppm; Secondary rinsing: The system pH is 6.5-7.2, free Fe... 3+ ≤1ppm, pesticide residue ≤10ppm; Three-stage rinsing: The system pH is 6.8-7.5, free Fe... 3+ ≤0.1ppm, particle surface cleanliness ≥Class 1000.

10. The ultrasonic-coupled chemical purification method for high-purity optical-grade calcite raw materials according to claim 1, characterized in that, In step 5), the drying temperature is 120-160℃, and the material is dried until the moisture content is ≤0.1%.