Method for preparing battery-grade sodium carbonate by efficiently removing impurities
By combining saturated washing and modified clinopterite adsorption technology, the problems of poor impurity removal and high production cost in the existing soda ash purification methods are solved, and a method for efficient and low-cost preparation of battery-grade sodium carbonate is achieved.
Patent Information
- Application Number
- CN202510197436.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-21
- Publication Date
- 2025-05-27
AI Technical Summary
The existing soda ash purification method is not effective in removing impurities from sodium carbonate, especially the removal effect of trace metal ions such as iron and copper is limited, and the production cost is high, making it difficult to meet the high purity needs of the battery industry.
Using a combination of "saturated washing + modified clinopterite adsorption", impurities are initially removed through the solubility difference of sodium carbonate at different temperatures, and then modified clinopterite adsorbs the residual trace impurities, and finally obtain high-purity battery-grade sodium carbonate.
It significantly improves the purity of sodium carbonate, effectively removes metal ions such as iron, potassium, copper, and zinc, reduces production costs, avoids environmental pollution, and is suitable for large-scale industrial production.
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Figure CN120039907A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for removing impurities from soda ash, and particularly to a method for efficiently removing impurities to prepare battery-grade sodium carbonate. Background Art
[0002] The production of sodium carbonate mainly includes the synthetic method and the natural soda method. The synthetic method is suitable for large-scale industrial production with high output, but has problems such as high energy consumption and difficult treatment of by-products. The natural soda method is simple to operate, has low equipment requirements, and does not require additional chemical reactions, but the product has a high impurity content. Due to the large number of associated minerals in natural soda mines, the impurity content in the raw brine after solution mining is high, and the impurity content doubles after multi-effect evaporation, seriously affecting the quality of soda ash and making it difficult to meet the requirements of high-end products such as the battery industry. In addition, the advantage of the natural soda industry lies in its "natural" characteristics, and production enterprises do not want to improve product performance through chemical reactions by adding chemical agents, which undoubtedly increases the difficulty of purifying soda ash products.
[0003] The purification of natural soda mainly includes traditional technologies such as crystallization method, solvent extraction method, and ion exchange method. These methods have obvious defects in removing impurities in battery-grade sodium carbonate. (1) Crystallization method: By adjusting the solution temperature and solubility, sodium carbonate crystallizes and impurities are separated from the solution. Although this method can remove some impurities with low solubility, it has poor removal effects on metal ions such as iron and copper (especially trace metal ions). During the crystallization process, impurities are easily crystallized together with sodium carbonate, resulting in low impurity removal efficiency and the purity of the obtained sodium carbonate cannot meet the requirements of battery-grade sodium carbonate. In addition, this method consumes a large amount of energy and time, resulting in high production costs. (2) Solvent extraction method: Using the affinity difference between organic solvents and solutes to separate impurities. This method is suitable for removing certain water-soluble impurities, but has limited removal effects on complex metal impurities in natural soda, especially metal ions such as iron and copper. Not only is the solvent consumption large, difficult to recycle, poor in environmental protection, and costly, but the use of solvents will also cause environmental pollution and increase the treatment difficulty. (3) Ion exchange method: Using different ion exchange resins or mineral adsorbents to remove metal ions in the solution. Some minerals in nature such as zeolite have strong ion exchange ability and can effectively adsorb metal ions in water. However, the traditional ion exchange method has problems such as long treatment cycle, limited treatment capacity, and poor adsorption of metal ions.
[0004] Therefore, there is an urgent need to improve the existing soda ash purification methods. Summary of the Invention
[0005] In view of the deficiencies of the prior art, the present invention provides a method for efficiently removing impurities to prepare battery-grade sodium carbonate.
[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:
[0007] A method for efficiently removing impurities to prepare battery-grade sodium carbonate, comprising the following steps:
[0008] (1) Weigh 30 - 50 g of soda ash sample S0, add it to the elutriation tank, add 100 - 150 mL of water to the elutriation tank, control the water temperature at 20 - 25 °C, elutriate for 1.5 - 2 h with stirring, and perform the first filtration after elutriation to obtain a filtrate and the elutriated soda ash sample S1;
[0009] (2) Weigh 20 - 25 g of battery-grade primary standard soda ash, add it together with soda ash sample S1 to an adsorption reaction tank containing 100 - 150 mL of water, control the water temperature at 25 - 30 °C, and completely dissolve the soda ash to obtain an adsorption reaction solution;
[0010] (3) Weigh 0.1 - 1 g of modified clinoptilolite, add it to the adsorption reaction solution, control the water temperature at 30 °C, stir for 4 - 6 h, perform the second filtration on the adsorbed mixture to separate the adsorbed modified clinoptilolite from the filtrate, and cool the filtrate to 20 °C;
[0011] (4) Perform the third filtration on the cooled mixture to obtain a filtrate and soda ash crystals, put the soda ash crystals into a drying oven, and dry until no crystal water is contained, thus obtaining the target product S2.
[0012] The preparation method of the modified clinoptilolite therein is as follows:
[0013] Wash natural clinoptilolite with water to remove surface dust and attachments, perform drying and screening to obtain 50 - 80 - mesh zeolite; then calcine the natural clinoptilolite at 200 °C for 2 h, cool it and place it in a NaOH solution with a concentration of 0.2 mol / L, and perform ultrasonic treatment for 2 h; take out the zeolite, wash it, and place it in an AlCl 3 solution and perform ultrasonic treatment for 2 h; finally take out the zeolite, wash it, put it into a NaCl solution with a mass concentration of 20%, boil it for 30 min, wash it with water and dry it at 105 °C for 2 h to obtain the modified clinoptilolite.
[0014] Preferably, in step (1), the soda ash sample S0 is 39.7 g, the added water is 100 mL, and the water temperature is 20 °C;
[0015] In step (2), the battery-grade primary soda ash sample is 21.5 g, and the water temperature is 30 °C;
[0016] In step (3), the dosage of the modified clinoptilolite is 0.5 g;
[0017] In step (4), the drying temperature is 100 - 200 °C, and the drying time is 2 - 4 h;
[0018] During stirring, magnetic stirring or electric stirring is adopted, and the stirring speed is 600 r / min. The filtrates after the first filtration and the third filtration are collected separately and used as the next eluent and adsorption reaction solution for recycling respectively.
[0019] Advantages of the present invention
[0020] (1) The present invention adopts the combined process of "saturated elution + zeolite adsorption". Utilizing the characteristic that the solubility of sodium carbonate varies greatly at different temperatures (the solubility of sodium carbonate in water is 21.5 g / 100 mL at 20 °C and 39.7 g / 100 mL at 30 °C), part of the impurities are removed first, and then the residual trace impurities are further adsorbed by the modified zeolite, and finally battery-grade sodium carbonate products are obtained. This process effectively solves the problems of poor impurity removal effect and high production cost in the purification process of sodium carbonate in the prior art.
[0021] (2) Compared with the traditional recrystallization process, the method of the present invention has the following advantages:
[0022] 1) High-efficiency impurity removal: Through the combined process of elution and modified zeolite adsorption, the removal effects of metal ions such as iron, potassium, copper, and zinc in sodium carbonate are remarkable, effectively improving the purity of sodium carbonate, and the product meets the sodium carbonate standard in the battery industry.
[0023] 2) Cost reduction: The present invention uses physical elution and modified zeolite to remove impurities, avoiding the use of a large amount of chemical reagents, which can reduce production costs and avoid environmental pollution.
[0024] 3) Simple operation: The whole process does not require complex chemical reagents and high-energy-consuming equipment, meeting the requirements of green production. The implementation process is simple and easy to operate, greatly improving production efficiency and reducing costs, and is suitable for large-scale industrial production.
[0025] (3) The modified clinoptilolite used in the present invention is obtained through processes such as high-temperature roasting, alkali solution ultrasonic desilication, aluminum solution treatment for aluminum supplementation, and salt modification. Compared with the unmodified one, the specific surface area and ion exchange capacity of the modified clinoptilolite are significantly improved, and it shows good adsorption performance especially in the removal of impurity elements such as K, Fe, Cu, Pb, Cr, and B, which is beneficial to improving the removal effect of impurities in sodium carbonate.
[0026] (4) During the modification process of the modified clinoptilolite of the present invention, the water and impurities in the zeolite pores are effectively dredged, and its pore structure is improved, increasing both the specific surface area and the mesoporous surface area of the zeolite. In addition, ions that are easily exchanged with K+ enter the zeolite pores during the modification process. This change reduces the average pore diameter of the zeolite and adsorbs on its surface, which is beneficial to the removal of impurity elements such as K in sodium carbonate by the modified clinoptilolite. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 Process flow chart of preparing battery-grade sodium carbonate by removing impurities according to the present invention. DETAILED DESCRIPTION OF THE INVENTION
[0028] The following further describes in detail the specific embodiments of the present invention with reference to the examples.
[0029] Example 1 A method for efficiently removing impurities to prepare battery-grade sodium carbonate, the specific steps are as follows:
[0030] (1) Weigh 39.7 g of soda ash sample S0, add it to the elution tank, add 100 mL of ultrapure water for laboratory use, turn on the magnetic stirrer, and elute for 1.5 h under the conditions of a rotation speed of 600 r / min and a water temperature of 20 °C. After elution, perform the first filtration to obtain a filtrate and eluted soda ash S1.
[0031] (2) Weigh 21.5 g of battery-grade primary soda ash, add it to the adsorption reaction tank together with soda ash S1, which contains 100 mL of ultrapure water, control the water temperature at 30 °C, and stir to completely dissolve the soda ash to obtain an adsorption reaction solution.
[0032] (3) Weigh 0.5 g of modified clinoptilolite, add it to the adsorption reaction solution, control the water temperature at 30 °C, keep the stirring speed at 600 r / min, and stir for 4 h; perform the second filtration on the adsorbed mixture to separate the adsorbed modified clinoptilolite from the filtrate, and cool the filtrate at 20 °C.
[0033] (4) Perform the third filtration on the cooled mixture to obtain a filtrate and soda ash crystals, put the soda ash crystals into a drying oven for drying, the drying temperature is 150 °C, and dry until no crystal water is contained, then the target product S2 is obtained.
[0034] Among them, collect the filtrates of the first and third filtrations, which can be used as the next eluent and adsorption reaction solution respectively.
[0035] Preparation method of the modified clinoptilolite in step (3):
[0036] Wash natural clinoptilolite with water to remove surface dust and attachments, dry and then screen to obtain zeolite powder with a particle size of 50 - 80 mesh; then, calcine the zeolite powder at 200 °C for 2 h, cool it and place it in a NaOH solution with a concentration of 0.2 mol / L, and perform ultrasonic treatment for 2 h; take out the zeolite, wash it, and then place it in AlCl with a concentration of 0.5 mol / L 3The solution was ultrasonically treated for 2 h; finally, the zeolite was taken out, washed, and then put into a 20% (mass concentration) NaCl solution and boiled for 30 min (the boiling process was repeated three times in total), washed with water, and dried at 105 °C for 2 h to obtain the modified clinoptilolite.
[0037] The used modified clinoptilolite was treated as solid waste.
[0038] Example 2 Performance analysis of the sodium carbonate product of the present invention
[0039] (1) A variety of impurities such as K, Ca, Fe, and Cu were detected in the original soda ash sample S0. These impurities mainly originated from the associated minerals rich in the natural soda ash mine. After the alkali mine was dissolved and collected, the impurity content in its original brine was relatively high, and these impurity contents increased significantly after multi-effect evaporation, resulting in a relatively high impurity content in S0.
[0040] The contents of impurity elements in the original soda ash sample S0 and soda ash S1 were analyzed by ICP-MS, as shown in Table 1.
[0041] The impurity content in the washed soda ash S1 decreased significantly, and the removal rates of impurity elements such as Ca, Fe, Mg, Zn, and Cu all reached over 75%, and the removal rates of impurity elements such as Al, Ni, and Cr reached over 40%. However, the removal effect of K element was not obvious and did not meet the standard of battery-grade sodium carbonate, and further purification was still required.
[0042] Table 1 Contents of impurities in soda ash sample S0 and washed soda ash S1 (%, ω)
[0043]
[0044] (2) ICP-MS full-scan analysis was carried out on the soda ash raw material S0 and the product S2, and the results are shown in Table 2.
[0045] The results showed that the removal effect of K element in the product S2 was prominent, and the removal rate increased from 27.98% of S1 to 98.78%. In addition, the removal rates of other impurity elements such as Fe, Cu, Pb, Cr, and B increased significantly. The contents of various impurities in the product S2 decreased significantly, and its quality reached the first-class standard of battery-grade sodium carbonate (T / HNSDCHYXH001-2023).
[0046] This result verified the advantages of the combined impurity removal process of the present invention, proving that this process can effectively remove impurities in sodium carbonate, and the obtained sodium carbonate meets the requirements of the battery industry.
[0047] Table 2 Contents of impurities in soda ash sample S0 and product S2 (%, ω)
[0048]
[0049] Example 3 Performance Test of Modified Clinoptilolite in the Present Invention
[0050] (1) The performance of the modified clinoptilolite obtained in Example 1 was measured, and the results are shown in Table 3 below.
[0051] It can be seen that compared with that before modification, the BET surface area of the modified clinoptilolite increased by 97.7%, the pore volume increased by 36.1%, and the average pore diameter decreased slightly.
[0052] Table 3 Comparison of Specific Surface Area and Pore Structure of Clinoptilolite before and after Modification
[0053]
[0054] (2) Dosage of Modified Clinoptilolite
[0055] 0.1 g, 0.3 g, 0.5 g, 0.7 g, and 1 g of the modified clinoptilolite in Example 1 were respectively taken and placed in a saturated sodium carbonate solution at 30 °C (prepared from 39.7 g of S0 and 100 mL of water). The rotation speed was controlled at 600 r / min and adsorption was carried out for 4 h to obtain the adsorption amounts under different conditions, as shown in Table 4.
[0056] It can be seen that with the increase of the dosage of the modified clinoptilolite, its adsorption amount gradually increases. When the dosage of clinoptilolite is greater than 0.5 g, the increase of its adsorption amount is slow. Considering comprehensively, the dosage of zeolite is selected as 0.5 g.
[0057] Table 4 Relationship between Dosage of Modified Clinoptilolite and Adsorption Amount
[0058]
Claims
1. A method for efficiently removing impurities to prepare battery-grade sodium carbonate, characterized in that: The method comprises the following steps: (1) Weigh 30-50 g of soda ash sample S0, add it to a washing tank, add 100-150 mL of water to the washing tank, control the water temperature to 20-25° C., wash for 1.5-2 h under stirring, and perform the first filtration after washing to obtain a filtrate and the washed soda ash sample S1; (2) Weigh 20-25 g of battery-grade primary standard soda ash and add it together with soda ash sample S1 into an adsorption reaction cell containing 100-150 mL of water, control the water temperature to 25-30° C., completely dissolve the soda ash, and obtain an adsorption reaction solution; (3) Weigh 0.1-1 g of modified clinoptilolite, add it to the adsorption reaction solution, control the water temperature to 30° C., stir for 4-6 h, filter the adsorbed mixed solution for the second time, separate the adsorbed modified clinoptilolite and the filtrate, and cool the filtrate at 20° C.; (4) The cooled mixture is filtered for a third time to obtain a filtrate and soda ash crystals. The soda ash crystals are placed in a drying oven and dried until no crystal water is contained, thereby obtaining the target product S2.
2. The method for efficiently removing impurities to prepare battery-grade sodium carbonate according to claim 1, characterized in that: The preparation method of modified clinoptilolite is: The natural clinoptilolite is washed with water to remove dust and attachments on the surface, dried and sieved to obtain a zeolite of 50-80 mesh; the natural clinoptilolite is then calcined at 200°C for 2 hours, cooled and placed in a 0.2 mol / L NaOH solution and ultrasonically treated for 2 hours; the zeolite is taken out and washed, and then placed in a 0.5 mol / L AlCl3 solution and ultrasonically treated for 2 hours; finally, the zeolite is taken out and washed, placed in a 20% NaCl solution by mass, boiled for 30 minutes, washed with water and dried at 105°C for 2 hours to obtain a modified clinoptilolite.
3. The method for preparing battery-grade sodium carbonate by efficiently removing impurities according to claim 1 or 2, characterized in that: The soda ash sample S0 in step (1) is 39.7 g, 100 mL of water is added, and the water temperature is 20°C.
4. The method for preparing battery-grade sodium carbonate by efficiently removing impurities according to claim 1 or 2, characterized in that: Step (2) The battery-grade first-grade soda ash sample is 21.5 g and the water temperature is 30°C.
5. The method for efficiently removing impurities to prepare battery-grade sodium carbonate according to claim 1 or 2, characterized in that: The amount of modified clinoptilolite used in step (3) is 0.5 g.
6. The method for efficiently removing impurities to prepare battery-grade sodium carbonate according to claim 1 or 2, characterized in that: The drying temperature in step (4) is 100-200° C. and the drying time is 2-4 hours.
7. The method for preparing battery-grade sodium carbonate by efficiently removing impurities according to claim 1 or 2, characterized in that: The stirring method is magnetic stirring or electric stirring, and the stirring speed is 600r / min.
8. The method for preparing battery-grade sodium carbonate by efficiently removing impurities according to claim 1 or 2, characterized in that: The filtrates after the first filtration and the third filtration are collected and recycled as the next washing liquid and adsorption reaction liquid respectively.