Method for removing phosphorus from fluosilicic acid

Abstract

The present application relates to fluorosilicic acid impurity removal technical field, disclose a kind of removal method of phosphorus in fluorosilicic acid, precipitant is added in fluorosilicic acid, so that phosphate in fluorosilicic acid is reacted with precipitant and precipitate is precipitated, then filtration separation is carried out, to obtain first precipitate and first solution, remove phosphate in fluorosilicic acid;The precipitant is at least one of soluble zirconium salt or soluble titanium salt.The method of the present application uses soluble zirconium salt or soluble titanium salt as the precipitant of phosphate, and the impurity removal process is simple and easy to operate;The method of the present application separates phosphoric acid in a strong acidic environment, and the precipitate obtained after phosphorus removal can be used as a precipitant again after treatment, achieving the effect of recycling the precipitant.

Description

Technical Field

[0001] This invention relates to the field of fluorosilicic acid impurity removal technology, and in particular to a method for removing phosphorus from fluorosilicic acid. Background Technology

[0002] Fluorosilicic acid is a typical inorganic acid with the chemical formula H₂SiF₆ and a molecular weight of approximately 144.09. Anhydrous fluorosilicic acid is a colorless gas with a pungent odor; its aqueous solution is strongly acidic, and when a concentrated solution (60-70%) is cooled, colorless fluorosilicic acid containing two molecules of water precipitates out (melting point 19°C); a 13.3% aqueous solution of fluorosilicic acid is the most stable and does not decompose upon distillation; commercially, it exists as an approximately 30% concentration aqueous solution, which is colorless, transparent, and fuming, with a relative density of 1.29-1.31 (15°C).

[0003] When industrial fluorosilicic acid purchased directly from the market has a high phosphorus content, it will affect the product quality during subsequent comprehensive utilization and may fail to meet customer requirements.

[0004] Therefore, there is an urgent need for a method to remove phosphorus from fluorosilicic acid to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a method for removing phosphorus from fluorosilicic acid, addressing the problems in the prior art.

[0006] To achieve the above objectives, the present invention is implemented according to the following technical solution: A method for removing phosphorus from fluorosilicic acid includes the following steps: A precipitant is added to a fluorosilicic acid solution, causing the phosphate ions in the fluorosilicic acid solution to react with the precipitant and precipitate. The precipitate is then separated by filtration to obtain the first precipitate and the first solution, thus removing the phosphate ions from the fluorosilicic acid.

[0007] Preferably, the fluorosilicic acid solution is an aqueous solution with a fluorosilicic acid content of 25-40 wt%; the phosphorus content, calculated as phosphorus pentoxide, is 3-8% of the mass of the fluorosilicic acid solution.

[0008] Preferably, the amount of precipitant added is calculated based on the phosphoric acid content in fluorosilicic acid, and is 1-1.3 times the theoretically calculated amount according to the chemical reaction equation between the precipitant and phosphoric acid in the fluorosilicic acid solution.

[0009] Preferably, the precipitant is at least one of a soluble zirconium salt or a soluble titanium salt.

[0010] Preferably, when a soluble zirconium salt is used as the precipitant, the first precipitate is zirconium phosphate precipitate; when a soluble titanium salt is used as the precipitant, the first precipitate is titanium phosphate precipitate.

[0011] Preferably, the soluble zirconium salt is at least one of zirconium oxychloride, zirconium oxysulfate, and zirconium fluorosilicate.

[0012] More preferably, the soluble zirconium salt is zirconium fluorosilicate.

[0013] Preferably, the soluble titanium salt is at least one of titanium oxychloride, titanium oxysulfate, and titanium fluorosilicate.

[0014] More preferably, the soluble titanium salt is titanium fluorosilicate.

[0015] Specifically, it includes the following steps: Soluble zirconium salts or soluble titanium salts (zirconium oxychloride, zirconium sulfate, zirconium fluorosilicate, titanium oxychloride, titanium sulfate, titanium fluorosilicate, etc.) are added to phosphoric acid containing phosphoric acid under stirring. This causes the phosphoric acid in the fluorosilicate to combine with zirconium or titanium to form zirconium phosphate or titanium phosphate precipitates, which are then removed by filtration.

[0016] Taking zirconium fluorosilicate as an example, its reaction equation is: 4H3PO4+3Zr(SiF6)2=Zr3(PO4)4+6H2SiF6; Taking titanium fluorosilicate as an example, its reaction equation is: 4H3PO4+3 Ti(SiF6)2=Ti3(PO4)4+6H2SiF6; Taking zirconium oxychloride as an example, its reaction equation is: 4H3PO4+3ZrOCl2=Zr3(PO4)4+3H2O+6HCl; Taking titanium oxychloride as an example, its reaction equation is as follows: 4H3PO4+3TiOCl2=Ti3(PO4)4+3H2O+6HCl; Taking zirconium oxysulfate as an example, its reaction equation is: 4H3PO4+3ZrOSO4=Zr3(PO4)4+3H2O+3H2SO4; Taking titanium oxysulfate as an example, its reaction equation is as follows: 4H3PO4+3TiO SO4=Ti3(PO4)4+3H2O+3H2SO4.

[0017] Zirconium oxychloride, titanium oxychloride, zirconium oxysulfate, and titanium oxysulfate are readily available raw materials for precipitating agents; zirconium fluorosilicate and titanium fluorosilicate are even more effective. However, when using zirconium oxychloride, titanium oxychloride, zirconium oxysulfate, or titanium oxysulfate as precipitants, subsequent processes can recycle the obtained zirconium phosphate or titanium phosphate to produce zirconium fluorosilicate and titanium fluorosilicate for reuse as precipitants for phosphorus removal.

[0018] In this invention, the first precipitate generated can be processed to generate a precipitant, thus enabling the precipitant to be reused.

[0019] Preferably, the first precipitate is dissolved in hydrofluoric acid with a concentration of 30-50 wt% at room temperature and then filtered to obtain a second solution; the second solution is reacted with potassium phosphate solution with a concentration of 18-24 wt% at 60℃ at room temperature to precipitate, and then filtered to separate the precipitate and obtain the second precipitate and phosphoric acid solution. The second precipitate reacts with a 30-40 wt% potassium hydroxide solution at 60-80°C to form a precipitate, which is then separated by filtration to obtain the third precipitate and potassium fluoride solution. The third precipitate is dissolved in a 25-35 wt% fluorosilicic acid solution at 50°C. The recovered product can be used as a precipitant to remove phosphoric acid from fluorosilicic acid.

[0020] Preferably, when the first precipitate is zirconium phosphate precipitate, the second solution contains fluorozirconic acid, the second precipitate is potassium fluorozirconate precipitate, and the third precipitate is metazirconic acid; When the first precipitate is titanium phosphate, the second solution contains fluorotitanic acid, the second precipitate is potassium fluorotitanate, and the third precipitate is metatitanic acid.

[0021] Preferably, the amount of hydrofluoric acid added is 1.05 times the theoretically calculated amount according to the chemical reaction equation of hydrogen fluoride in hydrofluoric acid and zirconium phosphate or titanium phosphate in the first precipitate; excess hydrofluoric acid will volatilize during subsequent phosphoric acid concentration and be absorbed and recycled with water. The amount of potassium phosphate added is 1.05 times the theoretically calculated amount according to the reaction equation of fluorozirconic acid or fluorotitanic acid in the second solution; excess potassium phosphate will precipitate during subsequent phosphoric acid concentration and be recovered by filtration. The amount of potassium hydroxide solution added should be based on the theoretically calculated amount according to the chemical reaction equation between potassium hydroxide in the potassium hydroxide solution and potassium fluorozirconate or potassium fluorotitanate in the second precipitate; finally, the final pH value should be controlled to be 7-7.5. The amount of fluorosilicic acid solution used should be 8-15 times the mass of titanium or zirconium in the fluorosilicic acid solution and the third precipitate zirconic acid or titanic acid.

[0022] When the first precipitate is zirconium phosphate, the reaction equation for the formation of the precipitant after treatment is as follows: (1) Treatment of zirconium phosphate: ① Zirconium phosphate reacts with hydrofluoric acid to produce fluorozirconic acid and phosphoric acid (at room temperature). Zr3(PO4)4+18HF=3H2ZrF6+4H3PO4; ② Fluorozyric acid reacts with potassium phosphate to produce potassium fluorozirconate and phosphoric acid (at room temperature). 3H2ZrF6+2K3PO4=3K2ZrF6+2H3PO4; ③ Potassium fluorozirconate reacts with potassium hydroxide to produce potassium fluoride and metazirconic acid (temperature 60-80℃) K₂ZrF₆ + 4KOH = H₂O ⇌ 3Zr + 6KF + H₂O; ④ Zirconic acid reacts with fluorosilicic acid to form zirconium fluorosilicate (temperature 50℃) H2O3Zr+2H2SiF6=Zr(SiF6)2+3H2O.

[0023] When the first precipitate is titanium phosphate, the process of generating a precipitant after treatment is as follows (similarly, when the first precipitate is zirconium phosphate, the principle of generating a precipitant after treatment is similar to that of titanium phosphate): Titanium phosphate reacts with hydrofluoric acid at room temperature to produce fluorotitanic acid and phosphoric acid. In the presence of a strong base, fluorotitanic acid reacts with the base to form a salt, and further reacts with the strong base to form metatitanic acid and alkali metal fluorides. The reaction is reversible depending on the acid-base environment. Specifically, the reaction process is as follows: The generated titanium phosphate precipitate is dissolved in hydrofluoric acid to produce fluorotitanic acid and phosphoric acid. Potassium phosphate solution (strong alkali) is added to the fluorotitanic acid in the filtered solution to react and precipitate potassium fluorotitanate (potassium fluorotitanate has very low solubility in water). The solution is then filtered to obtain solid potassium fluorotitanate and phosphoric acid solution.

[0024] Potassium fluorotitanate reacts with potassium hydroxide solution (a strong alkali) to produce metatitanic acid and potassium fluoride (the reaction of fluorotitanic acid with potassium hydroxide is neutralized with the theoretical amount of potassium hydroxide needed to produce potassium fluorotitanate; when potassium hydroxide is in excess and the temperature is raised to 60-80℃, potassium fluorotitanate reacts with potassium hydroxide to produce metatitanic acid and potassium fluoride). Metatitanic acid is obtained by filtration. The product obtained after dissolving metatitanic acid in fluorosilicic acid can be returned as a precipitant to remove phosphoric acid from fluorosilicic acid.

[0025] The reaction equations for the above process are as follows: (2) Treatment of titanium phosphate: ① Titanium phosphate reacts with hydrofluoric acid to produce fluorotitanic acid and phosphoric acid (at room temperature). Ti3(PO4)4+18HF=3H2TiF6+4H3PO4; ② Fluorotitanic acid reacts with potassium phosphate to produce potassium fluorotitanate and phosphoric acid (at room temperature). 3H2TiF6+2K3PO4=3K2TiF6+2H3PO4; ③ Potassium fluorotitanate reacts with potassium hydroxide to produce potassium fluoride and metatitanic acid (temperature 60-80℃). K₂TiF₆ + 4KOH = H₂O ⇌ 3Ti + 6KF + H₂O; ④ Metatitanic acid reacts with fluorosilicic acid to form titanium fluorosilicate (temperature 50℃) H2O3Ti+2H2SiF6=Ti(SiF6)2+3H2O.

[0026] Beneficial effects: The method of the present invention uses soluble zirconium salt or soluble titanium salt as precipitant for phosphate ions. The impurity removal process is simple and easy to operate. The method of the present invention separates phosphoric acid in a strongly acidic environment. The precipitate obtained after phosphorus removal can be reused as a precipitant after treatment, achieving the effect of precipitant recycling. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments. The illustrative embodiments and descriptions herein are used to explain the present invention, but are not intended to limit the present invention.

[0028] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0029] There are no particular restrictions on the purity of any of the raw materials used in this invention; however, it is preferred to use materials with conventional purity levels used in the field.

[0030] All processes in this invention are referred to by abbreviations that are common abbreviations in the field. Each abbreviation is clear and specific in its relevant application area, and those skilled in the art can understand its conventional process steps based on the abbreviation.

[0031] Example 1 A method for removing phosphorus from fluorosilicic acid includes the following steps: S1. Add a soluble zirconium salt (zirconium oxychloride) to a phosphorus-containing fluorosilicic acid solution while stirring. This causes the phosphoric acid in the fluorosilicic acid solution to combine with zirconium to form a precipitate of zirconium phosphate. After filtration and separation, the phosphoric acid can be removed. The fluorosilicic acid solution is an aqueous solution with a fluorosilicic acid content of 32 wt%; the phosphorus content, calculated as phosphorus pentoxide, is 5% of the mass of the fluorosilicic acid solution. The amount of precipitant added was calculated based on the phosphoric acid content in fluorosilicic acid, and was 1.2 times the theoretically calculated amount according to the chemical reaction equation between the precipitant and phosphoric acid in the fluorosilicic acid solution; after filtration and separation, the phosphorus content in the fluorosilicic acid, calculated as phosphorus pentoxide, was 0.057%. S2, the generated zirconium phosphate precipitate is dissolved in 40wt% hydrofluoric acid at room temperature. The filtered solution is then reacted with 20wt% potassium phosphate solution at 60℃ at room temperature to form potassium fluorozirconate precipitate. The precipitate is obtained by filtration, yielding potassium fluorozirconate and phosphoric acid solution. The amount of hydrofluoric acid and potassium phosphate added is 1.05 times the theoretically calculated amount. S3, potassium fluorozirconate reacts with a 35wt% potassium hydroxide solution at 70℃ to produce metazirconic acid and potassium fluoride, and the metazirconic acid is obtained by filtration; the amount of potassium hydroxide added is the theoretical calculation amount; after adding according to the theoretical amount, the final pH value is controlled to be 7.2. S4, the product generated by dissolving zirconic acid in a 30wt% fluorosilicic acid solution at 50°C can be returned as a precipitant to remove phosphoric acid from fluorosilicic acid; The amount of fluorosilicic acid solution used is 11 times the mass of zirconium in the fluorosilicic acid and zirconic acid solutions.

[0032] Example 2 A method for removing phosphorus from fluorosilicic acid includes the following steps: S1. Add a soluble zirconium salt (zirconium oxysulfate) to a phosphoric acid solution containing phosphoric acid while stirring. This causes the phosphoric acid in the fluorosilicic acid solution to combine with zirconium to form a zirconium phosphate precipitate, which can be removed by filtration. The fluorosilicic acid solution is an aqueous solution with a fluorosilicic acid content of 25 wt%; the phosphorus content, calculated as phosphorus pentoxide, is 3% of the mass of the fluorosilicic acid solution. The amount of precipitant added was calculated based on the phosphoric acid content in the fluorosilicic acid, and was 1.1 times the theoretically calculated amount according to the chemical reaction equation between the precipitant and phosphoric acid in the fluorosilicic acid solution. After filtration and separation, the phosphorus content in the fluorosilicic acid, calculated as phosphorus pentoxide, was found to be 0.064%. S2, the generated zirconium phosphate precipitate was dissolved in 30wt% hydrofluoric acid at room temperature. The filtered solution was then reacted with 22wt% potassium phosphate solution at 60℃ at room temperature to form potassium fluorozirconate precipitate. The precipitate was obtained by filtration, yielding potassium fluorozirconate and phosphoric acid solution. The amount of hydrofluoric acid and potassium phosphate added was 1.05 times the theoretically calculated amount. S3, potassium fluorozirconate reacts with a 30wt% potassium hydroxide solution at 60℃ to produce metazirconic acid and potassium fluoride, and the metazirconic acid is obtained by filtration; the amount of potassium hydroxide added is the theoretical calculation amount; after adding according to the theoretical amount, the final pH value is controlled to be 7.1; S4, the product generated by dissolving zirconic acid in a 25wt% fluorosilicic acid solution at 50°C can be returned as a precipitant to remove phosphoric acid from fluorosilicic acid; The amount of fluorosilicic acid solution used is 8 times the mass of zirconium in the fluorosilicic acid solution and the zirconium in the metazirconic acid solution.

[0033] Example 3 A method for removing phosphorus from fluorosilicic acid includes the following steps: S1. Add a soluble zirconium salt (zirconium fluorosilicate) to a phosphoric acid solution containing phosphoric acid while stirring. This causes the phosphoric acid in the solution to combine with the zirconium to form a precipitate of zirconium phosphate. After filtration and separation, the phosphoric acid can be removed. The fluorosilicic acid solution is an aqueous solution with a fluorosilicic acid content of 40 wt%; the phosphorus content, calculated as phosphorus pentoxide, is 8% of the mass of the fluorosilicic acid solution. The amount of precipitant added was calculated based on the phosphoric acid content in the fluorosilicic acid, and was 1.3 times the theoretically calculated amount according to the chemical reaction equation between the precipitant and phosphoric acid in the fluorosilicic acid solution. After filtration and separation, the phosphorus content in the fluorosilicic acid, calculated as phosphorus pentoxide, was found to be 0.036%. S2, the generated zirconium phosphate precipitate is dissolved in 50wt% hydrofluoric acid at room temperature. The filtered solution is then reacted with 24wt% potassium phosphate solution at 60℃ at room temperature to form potassium fluorozirconate precipitate. The precipitate is obtained by filtration, yielding potassium fluorozirconate and phosphoric acid solution. The amount of hydrofluoric acid and potassium phosphate added is 1.05 times the theoretically calculated amount. S3, potassium fluorozirconate reacts with a 40wt% potassium hydroxide solution at 80℃ to produce metazirconic acid and potassium fluoride, and the metazirconic acid is obtained by filtration; the amount of potassium hydroxide added is the theoretical calculation amount; after adding according to the theoretical amount, the final pH value is controlled to be 7.3; S4, the product generated by dissolving zirconic acid in a 35wt% fluorosilicic acid solution at 50°C can be returned as a precipitant to remove phosphoric acid from fluorosilicic acid; The amount of fluorosilicic acid solution used is 15 times the mass of zirconium in the fluorosilicic acid solution and the zirconium in the metazirconic acid solution.

[0034] Example 4 A method for removing phosphorus from fluorosilicic acid includes the following steps: S1. Add a soluble titanium salt (titanium oxychloride) to a phosphorus-containing fluorosilicic acid solution while stirring. This causes the phosphoric acid in the fluorosilicic acid solution to combine with titanium to form titanium phosphate precipitate, which can be removed by filtration. The fluorosilicic acid solution is an aqueous solution with a fluorosilicic acid content of 32 wt%; the phosphorus content is calculated as phosphorus pentoxide and is 5% of the mass of the fluorosilicic acid solution. The amount of precipitant added was calculated based on the phosphoric acid content in the fluorosilicic acid, and was 1.2 times the theoretically calculated amount according to the chemical reaction equation between the precipitant and phosphoric acid in the fluorosilicic acid solution. After filtration and separation, the phosphorus content in the fluorosilicic acid, calculated as phosphorus pentoxide, was found to be 0.061%. S2, the generated titanium phosphate precipitate was dissolved in 40wt% hydrofluoric acid at room temperature. The filtered solution was then reacted with 18wt% potassium phosphate solution at 60℃ at room temperature to form potassium fluorotitanate precipitate. The precipitate was obtained by filtration, yielding potassium fluorotitanate and phosphoric acid solution. The amount of hydrofluoric acid and potassium phosphate added was 1.05 times the theoretically calculated amount. S3, potassium fluorotitanate reacts with a 35wt% potassium hydroxide solution at 65℃ to produce metatitanic acid and potassium fluoride, and the metatitanic acid is obtained by filtration; the amount of potassium hydroxide added is the theoretical calculation amount; after adding according to the theoretical amount, the final pH value is controlled to be 7.0. S4, the product generated by dissolving metatitanic acid in a 30wt% fluorosilicic acid solution at 50°C can be returned as a precipitant to remove phosphoric acid from fluorosilicic acid; The amount of fluorosilicic acid solution used is 11 times the mass of titanium in the fluorosilicic acid and metatitanic acid solutions.

[0035] Example 5 A method for removing phosphorus from fluorosilicic acid includes the following steps: S1. Add a soluble titanium salt (titanium sulfate) to a phosphorus-containing fluorosilicic acid solution while stirring. This causes the phosphoric acid in the fluorosilicic acid solution to combine with titanium to form titanium phosphate precipitate, which can be removed by filtration. The fluorosilicic acid solution is an aqueous solution with a fluorosilicic acid content of 25 wt%; the phosphorus content is calculated as phosphorus pentoxide and is 3% of the mass of the fluorosilicic acid solution. The amount of precipitant added was calculated based on the phosphoric acid content in the fluorosilicic acid, and was 1.2 times the theoretically calculated amount according to the chemical reaction equation between the precipitant and phosphoric acid in the fluorosilicic acid solution. After filtration and separation, the phosphorus content in the fluorosilicic acid, calculated as phosphorus pentoxide, was found to be 0.049%. S2, the generated titanium phosphate precipitate was dissolved in 30wt% hydrofluoric acid at room temperature. The filtered solution was then reacted with 18wt% potassium phosphate solution at 60℃ at room temperature to form potassium fluorotitanate precipitate. The precipitate was obtained by filtration, yielding potassium fluorotitanate and phosphoric acid solution. The amount of hydrofluoric acid and potassium phosphate added was 1.05 times the theoretically calculated amount. S3, potassium fluorotitanate reacts with a 30wt% potassium hydroxide solution at 75℃ to produce metatitanic acid and potassium fluoride, and the metatitanic acid is obtained by filtration; the amount of potassium hydroxide added is the theoretical calculation amount; after adding according to the theoretical amount, the final pH value is controlled to be 7.5. S4, the product generated by dissolving metatitanic acid in a 25wt% fluorosilicic acid solution at 50°C can be returned as a precipitant to remove phosphoric acid from fluorosilicic acid; The amount of fluorosilicic acid solution used is 8 times the mass of titanium in the fluorosilicic acid and metatitanic acid solutions.

[0036] Example 6 A method for removing phosphorus from fluorosilicic acid includes the following steps: S1. Add a soluble titanium salt (titanium fluorosilicate) to a phosphorus-containing fluorosilicic acid solution while stirring. This causes the phosphoric acid in the fluorosilicic acid solution to combine with titanium to form titanium phosphate precipitate, which can be removed by filtration. The fluorosilicic acid solution is an aqueous solution with a fluorosilicic acid content of 40 wt%; the phosphorus content, calculated as phosphorus pentoxide, is 8% of the mass of the fluorosilicic acid solution. The amount of precipitant added was calculated based on the phosphoric acid content in the fluorosilicic acid, and was 1.3 times the theoretically calculated amount according to the chemical reaction equation between the precipitant and phosphoric acid in the fluorosilicic acid solution. After filtration and separation, the phosphorus content in the fluorosilicic acid, calculated as phosphorus pentoxide, was found to be 0.037%. S2, the generated titanium phosphate precipitate is dissolved in 50wt% hydrofluoric acid at room temperature. The filtered solution is then reacted with 20wt% potassium phosphate solution at 60℃ at room temperature to form potassium fluorotitanate precipitate. The precipitate is obtained by filtration, yielding potassium fluorotitanate and phosphoric acid solution. The amount of hydrofluoric acid and potassium phosphate added is 1.05 times the theoretically calculated amount. S3, potassium fluorotitanate reacts with a 40wt% potassium hydroxide solution at 70℃ to produce metatitanic acid and potassium fluoride, and the metatitanic acid is obtained by filtration; the amount of potassium hydroxide added is the theoretical calculation amount; after adding according to the theoretical amount, the final pH value is controlled to be 7.4. S4, the product generated by dissolving metatitanic acid in a 35wt% fluorosilicic acid solution at 50°C can be returned as a precipitant to remove phosphoric acid from fluorosilicic acid; The amount of fluorosilicic acid solution used is 15 times the mass of titanium in the fluorosilicic acid and metatitanic acid solutions.

[0037] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A method for removing phosphorus from fluorosilicic acid, characterized in that, Includes the following steps: A precipitant is added to a fluorosilicic acid solution, causing the phosphate ions in the fluorosilicic acid solution to react with the precipitant and precipitate. The precipitate is then separated by filtration to obtain the first precipitate and the first solution, thus removing the phosphate ions from the fluorosilicic acid.

2. The method for removing phosphorus from fluorosilicic acid according to claim 1, characterized in that: The fluorosilicic acid solution is an aqueous solution with a fluorosilicic acid content of 25-40 wt%; the phosphorus content, calculated as phosphorus pentoxide, is 3-8% of the mass of the fluorosilicic acid solution.

3. The method for removing phosphorus from fluorosilicic acid according to claim 1, characterized in that: The amount of precipitant added is calculated based on the phosphoric acid content in fluorosilicic acid, and is added at 1-1.3 times the theoretically calculated amount according to the chemical reaction equation between the precipitant and phosphoric acid in the fluorosilicic acid solution. The precipitant is at least one of a soluble zirconium salt or a soluble titanium salt.

4. The method for removing phosphorus from fluorosilicic acid according to claim 3, characterized in that: When a soluble zirconium salt is used as the precipitant, the first precipitate is zirconium phosphate; when a soluble titanium salt is used as the precipitant, the first precipitate is titanium phosphate.

5. The method for removing phosphorus from fluorosilicic acid according to claim 4, characterized in that: The soluble zirconium salt is at least one of zirconium oxychloride, zirconium oxysulfate, and zirconium fluorosilicate.

6. The method for removing phosphorus from fluorosilicic acid according to claim 4, characterized in that: The soluble titanium salt is at least one of titanium oxychloride, titanium oxysulfate, and titanium fluorosilicate.

7. The method for removing phosphorus from fluorosilicic acid according to claim 4, characterized in that: The first precipitate was dissolved in hydrofluoric acid with a concentration of 30-50 wt% at room temperature and then filtered to obtain the second solution. The second solution was reacted with a 18-24 wt% potassium phosphate solution at 60℃ at room temperature to precipitate the precipitate, which was then separated by filtration to obtain the second precipitate and the phosphoric acid solution. The second precipitate reacts with a 30-40 wt% potassium hydroxide solution at 60-80°C to form a precipitate, which is then separated by filtration to obtain the third precipitate and potassium fluoride solution. The third precipitate is dissolved in a 25-35 wt% fluorosilicic acid solution at 50°C. The recovered product can be used as a precipitant to remove phosphoric acid from fluorosilicic acid.

8. The method for removing phosphorus from fluorosilicic acid according to claim 8, characterized in that: When the first precipitate is zirconium phosphate, the second solution contains fluorozirconic acid, the second precipitate is potassium fluorozirconate, and the third precipitate is metazirconic acid; When the first precipitate is titanium phosphate, the second solution contains fluorotitanic acid, the second precipitate is potassium fluorotitanate, and the third precipitate is metatitanic acid.

9. The method for removing phosphorus from fluorosilicic acid according to claim 8, characterized in that: The amount of hydrofluoric acid added is 1.05 times the theoretically calculated amount according to the chemical reaction equation of hydrogen fluoride in hydrofluoric acid and zirconium phosphate or titanium phosphate in the first precipitate; The amount of potassium phosphate added is 1.05 times the theoretically calculated amount according to the reaction equation of fluorozirconic acid or fluorotitanic acid in the second solution; The amount of potassium hydroxide solution added should be based on the theoretically calculated amount according to the chemical reaction equation between potassium hydroxide in the potassium hydroxide solution and potassium fluorozirconate or potassium fluorotitanate in the second precipitate; finally, the final pH value should be controlled to be 7-7.

5. The amount of fluorosilicic acid solution used is 8-15 times the mass of fluorosilicic acid in the fluorosilicic acid solution and the titanium or zirconium in the third precipitate zirconic acid or metatitanic acid.