Method for preparing potassium fluosilicate by recovering fluorine-potassium-containing silicon dioxide by-product

Abstract

The invention discloses a method for recovering and preparing potassium fluosilicate from fluorine-potassium-containing silicon dioxide solid by-products, and belongs to the technical field of inorganic fluoride salt, the fluorine-potassium-containing silicon dioxide solid by-products are mixed with sulfuric acid or hydrochloric acid for acid immersion cleaning, then primary solid-liquid separation is carried out, and filter residues rich in silicon dioxide and first filtrate are obtained; carrying out secondary temperature-controlled washing and secondary solid-liquid separation on the filter residue to obtain a purified silicon dioxide product and a second filtrate; and combining the first filtrate and the second filtrate, adding fluosilicic acid into the combined filtrate according to a chemical reaction stoichiometric ratio, reacting at the temperature not lower than 50 DEG C to generate potassium fluosilicate crystals, and finally performing solid-liquid separation, washing and drying to obtain a potassium fluosilicate product. According to the method, potassium recycling is achieved, waste acid liquid after reaction is returned to the immersion cleaning process for recycling, zero emission of acid is achieved, meanwhile, the purity of the by-product silicon dioxide is improved to 85% or above through the simple acid immersion cleaning process, the purity of the silicon dioxide can be improved to 90% or above through secondary washing, and the method is suitable for industrial production. And the total yield of potassium fluosilicate is remarkably improved, the product recovery rate reaches 95% or above, and good economic benefits and social benefits are achieved.

Description

Technical Field

[0001] This invention belongs to the field of inorganic fluoride salt technology, and more specifically, relates to a method for recovering and preparing potassium fluorosilicate from fluorine-containing potassium silicate solid byproducts. Background Technology

[0002] Current Status of Potassium Resources: The current market price of potassium resources is relatively high, mainly due to the influence of supply and demand. Global demand for potash fertilizer continues to grow, especially in the agricultural sector, while supply faces certain constraints. Furthermore, the potassium production process generates numerous byproduct residues, such as SiO2 containing F / K, which not only increases production costs but may also have environmental impacts.

[0003] Current technological challenges: Current potassium resource extraction and processing technologies suffer from low production efficiency, high energy consumption, and environmental pollution. Solving these problems may encounter technical bottlenecks and high economic costs; for example, improving production efficiency while reducing energy consumption and minimizing byproduct residues requires substantial investment in research and development and technical support.

[0004] Market Outlook: With global population growth and agricultural modernization, the demand for potash fertilizer will continue to grow steadily. Future market development will rely on technological innovation, through improved production processes and the development of new technologies to reduce costs, increase efficiency, and minimize environmental pollution. Therefore, the current market price of potash resources is high, and the production process suffers from significant byproduct residues. Technological innovation is urgently needed to address existing technical problems, improve production efficiency and environmental protection, and meet the ever-increasing market demand. Summary of the Invention

[0005] To address the above deficiencies, this invention provides a method for recovering and preparing potassium fluorosilicate from fluorine-containing potassium silicate solid byproducts, comprising the following steps: a) Acid leaching: The fluorine-containing potassium silica solid byproduct is mixed with sulfuric acid or hydrochloric acid in the first reaction vessel for acid leaching to dissolve the potassium and fluorine in the byproduct to form a first mixed solution; b) First solid-liquid separation: The first mixture is subjected to solid-liquid separation to obtain a filter residue rich in silica and a first filtrate; c) Secondary temperature-controlled washing: The silica-rich filter residue obtained in step b) is transferred to the second reaction vessel, pure water or dilute acid solution is added, and a second stirring and washing is carried out at a certain temperature to further wash out the potassium and fluorine ions remaining in the filter residue. Then, a second solid-liquid separation is carried out to obtain the purified silica product and the second filtrate. d) Combining and reacting the filtrate: Combine the first filtrate and the second filtrate to obtain a mixed filtrate; add fluorosilicic acid to the mixed filtrate and react at a temperature not lower than 50°C to crystallize potassium fluorosilicate; e) The slurry after reaction is subjected to solid-liquid separation, washing and drying to obtain potassium fluorosilicate product.

[0006] Furthermore, the temperature of the secondary temperature-controlled washing is 30-50℃.

[0007] Furthermore, the secondary temperature-controlled washing is performed using pure water or a dilute acid solution.

[0008] Furthermore, in step a), the pH of the slurry is adjusted to 7 using sulfuric acid or hydrochloric acid.

[0009] Furthermore, in step d), the reaction temperature is 50-80℃.

[0010] Furthermore, the acid immersion time in step a) is 30-120 min.

[0011] Furthermore, in step e), the waste acid solution containing potassium fluorosilicate generated after the reaction is returned to step a) for recycling.

[0012] Compared with the prior art, the present invention has the following advantages: 1. The method of this invention not only realizes the recovery and utilization of potassium, but also allows the waste acid solution after the reaction to be returned to the leaching process for recycling, achieving zero acid discharge and having great social benefits.

[0013] 2. This invention improves the purity of the by-product silica to over 85% through a simple acid leaching process, achieving comprehensive utilization of resources and resulting in significant economic benefits.

[0014] 3. Improved yield and product purity: Through the unique secondary temperature-controlled washing step of this invention, not only is the purity of silica products increased from over 85% to over 90%, but potassium and fluoride ions remaining in the micropores of the filter residue are also effectively recovered into the second filtrate. By merging the filtrates, the total yield of potassium fluorosilicate is significantly improved.

[0015] 4. The "one-time leaching + two-time temperature-controlled washing and recycling" combined process is a systematic solution designed for the treatment of specific complex solid wastes. Through multi-step separation, washing and merging operations, it achieves a synergistic improvement in the yield of the two target products (purified silica and potassium fluorosilicate). It is fundamentally different from conventional liquid phase treatment methods or simple solid-liquid separation methods and has significant progress. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1

[0018] This embodiment provides a method for recovering and preparing potassium fluorosilicate from fluorine-containing potassium silicate solid byproducts, including the following steps: A method for recovering and preparing potassium fluorosilicate from fluorine-containing potassium silicate solid byproducts includes the following steps: (a) Acid leaching: Take 1000 kg of solid byproduct containing potassium fluoride silica (containing 70% silica, 10% fluorine and 10% potassium) and add it to the reaction vessel. Add 500 kg of water and slowly add 98% sulfuric acid while stirring. Adjust the pH to 7 and the acid leaching time is 60 min. (b) First solid-liquid separation: The slurry obtained in step (a) is subjected to a first solid-liquid separation to obtain filter residue 1 and filtrate 1; (c) Secondary temperature-controlled washing: Transfer the filter residue 1 obtained in step (b) to another reactor, add 500 kg of pure water, and stir and wash at 40°C (in this embodiment, the temperature of the secondary temperature-controlled washing is 40°C within the range of 30-50°C) for 60 minutes. Then perform a second solid-liquid separation to obtain purified silica filter residue 2 and filtrate 2; (d) Combining and reacting the filtrate: Combine the filtrate 1 obtained in step (b) and the filtrate 2 obtained in step (c) in a reaction vessel to obtain a mixed filtrate; add 1440 kg of fluorosilicic acid with a concentration of 25% to the mixed filtrate, react at 60°C (in this embodiment, the reaction temperature is 60°C within the range of 50-80°C) for 60 min, and then cool to crystallize; (e) The slurry after the reaction in step (d) is subjected to solid-liquid separation, washing, and drying to obtain potassium fluorosilicate product. In addition, the waste acid solution generated in this step is returned to step (a) for recycling.

[0019] The final conclusion was that a silica product with a purity of 91.5% and a potassium fluorosilicate product with a total yield of 97.1% were obtained.

[0020] Example 2

[0021] This embodiment provides a method for recovering and preparing potassium fluorosilicate from fluorine-containing potassium silicate solid byproducts, including the following steps: (a) Acid leaching: Take 1000 kg of solid byproduct containing potassium fluoride silica (containing 70% silica, 10% fluorine and 10% potassium) and add it to the reaction vessel. Add 500 kg of water and slowly add 98% sulfuric acid while stirring. Adjust the pH to 7 and the acid leaching time is 90 min. (b) First solid-liquid separation: The slurry obtained in step (a) is subjected to a first solid-liquid separation to obtain filter residue 1 and filtrate 1; (c) Secondary temperature-controlled washing: The filter residue 1 obtained in step (b) is transferred to another reactor, 500 kg of pure water is added, and the mixture is stirred and washed at 30°C for 60 minutes. Then, a second solid-liquid separation is performed to obtain purified silica filter residue 2 and filtrate 2. (d) Combining and reacting the filtrate: Combine the filtrate 1 obtained in step (b) and the filtrate 2 obtained in step (c) in a reaction vessel to obtain a mixed filtrate; add 1440 kg of fluorosilicic acid with a concentration of 25% to the mixed filtrate, react at 80°C for 60 min, and then cool to crystallize. (e) The slurry after the reaction in step (d) is subjected to solid-liquid separation, washing, and drying to obtain potassium fluorosilicate product. In addition, the waste acid solution generated in this step is returned to step (a) for recycling.

[0022] The final conclusion is that a silica product with a purity of 90.8% and a potassium fluorosilicate product with a total yield of 96.5% were obtained.

[0023] Example 3

[0024] This embodiment provides a method for recovering and preparing potassium fluorosilicate from fluorine-containing potassium silicate solid byproducts, including the following steps: (a) Acid immersion: Take 1000 kg of solid byproduct containing potassium fluoride silica (containing 70% silica, 10% fluorine and 10% potassium) and add it to the reaction vessel. Add 500 kg of water and slowly add hydrochloric acid while stirring to adjust the pH to 7. The acid immersion time is 120 min. (b) First solid-liquid separation: The slurry obtained in step (a) is subjected to a first solid-liquid separation to obtain filter residue 1 and filtrate 1; (c) Secondary temperature-controlled washing: The filter residue 1 obtained in step (b) is transferred to another reactor, and 500 kg of dilute sulfuric acid solution is added. The mixture is stirred and washed at 50°C for 60 minutes. Then, a second solid-liquid separation is performed to obtain purified silica filter residue 2 and filtrate 2. (d) Combining and reacting the filtrate: Combine the filtrate 1 obtained in step (b) and the filtrate 2 obtained in step (c) in a reaction vessel to obtain a mixed filtrate; add 1440 kg of fluorosilicic acid with a concentration of 25% to the mixed filtrate, react at 50°C for 60 min, and then cool to crystallize. (e) The slurry after the reaction in step (d) is subjected to solid-liquid separation, washing, and drying to obtain potassium fluorosilicate product. In addition, the waste acid solution generated in this step is returned to step (a) for recycling.

[0025] The final conclusion is that a silica product with a purity of 92.1% and a potassium fluorosilicate product with a total yield of 97.8% were obtained.

[0026] Comparative Example 1 The steps correspond to the scheme after omitting the first part of steps (c) and (d) in Examples 1-3, and the specific steps are as follows: (a) Take 1000 kg of solid byproduct containing potassium fluoride silica (containing 70% silica, 10% fluorine, and 10% potassium) and add it to the reaction vessel. Add 500 kg of water and slowly add 98% sulfuric acid while stirring. Adjust the pH to 7 and stir the reaction for 60 min. (b) The slurry obtained in step (a) is subjected to solid-liquid separation to obtain filter residue (silica product) and filtrate; (c) Add 1440 kg of fluorosilicic acid with a concentration of 25% to the filtrate obtained in step (b), react at 60°C for 60 min, cool to crystallize, and obtain potassium fluorosilicate product by filtration, washing and drying. (d) Return the waste acid solution generated in step (c) to step (a) for recycling.

[0027] Measurements revealed a silica product with a purity of 85.2%. Potassium fluorosilicate was also obtained, with an overall yield of 92.5%. The key results of Comparative Example 1 and Examples 1-3 are summarized in Table 1 below: Table 1 Examples / Comparative Examples Second wash Filtrate Combination final purity of silica Total yield of potassium fluorosilicate Comparative Example 1 no no 85.2% 92.5% Example 1 yes yes 91.5% 97.1% Example 2 yes yes 90.8% 96.5% Example 3 yes yes 92.1% 97.8% As shown in Table 1 above, compared with Comparative Example 1, which did not employ secondary washing and filtrate merging, Examples 1-3 all achieved significant technical progress under similar or varying conditions: 1. The purity of silica products has been significantly improved: from 85.2% to over 90%, resulting in higher product quality and greater economic value.

[0028] 2. The total yield of potassium fluorosilicate has been significantly improved: from 92.5% to over 96%, resulting in higher resource utilization and effectively reducing production costs.

[0029] It should be noted that the structure described in this invention can be implemented in many different forms and is not limited to the embodiments described. Any equivalent transformations made by those skilled in the art based on the content of this specification, or direct or indirect applications in other related technical fields, such as the loading and unloading of other items, are included within the protection scope of this invention.

Claims

1. A method for recovering and preparing potassium fluorosilicate from fluorine-containing potassium silicate solid byproducts, characterized in that, Includes the following steps: a) Acid leaching: The fluorine-containing potassium silica solid byproduct is mixed with sulfuric acid or hydrochloric acid in the first reaction vessel for acid leaching to dissolve the potassium and fluorine in the byproduct to form a first mixed solution; b) First solid-liquid separation: The first mixture is subjected to solid-liquid separation to obtain a filter residue rich in silica and a first filtrate; c) Secondary temperature-controlled washing: The silica-rich filter residue obtained in step b) is transferred to the second reaction vessel, pure water or dilute acid solution is added, and a second stirring and washing is carried out at a certain temperature to further wash out the potassium and fluorine ions remaining in the filter residue. Then, a second solid-liquid separation is carried out to obtain the purified silica product and the second filtrate. d) Combining and reacting the filtrate: Combine the first filtrate and the second filtrate to obtain a mixed filtrate; add fluorosilicic acid to the mixed filtrate and react at a temperature not lower than 50°C to crystallize potassium fluorosilicate; e) The slurry after reaction is subjected to solid-liquid separation, washing and drying to obtain potassium fluorosilicate product.

2. The method for recovering and preparing potassium fluorosilicate from fluorine-containing potassium silicate solid byproducts as described in claim 1, characterized in that: The temperature of the secondary temperature-controlled washing is 30-50℃.

3. The method for recovering and preparing potassium fluorosilicate from fluorine-containing potassium silicate solid byproducts as described in claim 2, characterized in that: The secondary temperature-controlled washing process uses pure water or a dilute acid solution.

4. The method as described in claim 1, characterized in that: In step a), the pH of the slurry is adjusted to 7 using sulfuric acid or hydrochloric acid.

5. The method as described in claim 1, characterized in that: In step d), the reaction temperature is 50-80℃.

6. The method as claimed in claim 1, characterized in that: The acid immersion time in step a) is 30-120 minutes.

7. The method as claimed in claim 1, characterized in that: In step e), the waste acid solution containing potassium fluorosilicate generated after the reaction is returned to step a) for recycling.