A method for comprehensive utilization, separation and purification of calcium fluoride sludge

Abstract

The invention relates to the technical field of calcium fluoride sludge treatment, and in particular to a method for comprehensive utilization, separation and purification of calcium fluoride sludge, which is used to solve the problem that fluorine-containing sludge is difficult to treat, which not only causes waste of resources but also causes pollution to the environment. The method can simultaneously comprehensively utilize fluorine-containing waste acid and calcium fluoride sludge, separate and purify useful substances therein and reuse them, and the obtained hydrofluoric acid and acid solution reduce the production cost of the enterprise, and the obtained calcium fluorosilicate and potassium fluorosilicate can be directly sold, have high market value, and have significant economic benefits. The method not only improves resource utilization and reduces the impact on the environment, but is also easy to trial and promote.

Description

Technical Field

[0001] The invention relates to the technical field of calcium fluoride sludge treatment, and in particular to a method for comprehensive utilization, separation and purification of calcium fluoride sludge. Background Art

[0002] After treating industrial fluoride-containing wastewater with lime chemical precipitation method, a large amount of fluoride-containing sludge will inevitably be produced. The composition of this sludge varies with the products produced by the enterprise. At present, the main component of fluoride-containing sludge produced in the production process of photovoltaic, semiconductor and panel industries is calcium fluoride, and it also contains impurities such as calcium carbonate and calcium fluorosilicate. Some enterprises choose to pile up the sludge in the open air, while others choose to transport it as waste and hand it over to qualified waste disposal companies for treatment. Most waste disposal companies will mix it with cement to solidify bricks, which will be used as low-end sewage pipes, industrial building materials, etc. In the above methods, fluorine will be released into the environment again. In the long run, it will inevitably increase the fluoride concentration in groundwater and cause environmental pollution.

[0003] If calcium fluoride is extracted from the sludge, it can not only avoid secondary pollution of groundwater caused by sludge, but also make full use of fluorine resources, which is of great significance to the treatment of calcium fluoride sludge. Therefore, the purpose of this study is to find a comprehensive utilization, separation and purification method for calcium fluoride sludge to solve the above problems. Summary of the invention

[0004] In order to overcome the above technical problems, the object of the present invention is to provide a method for comprehensive utilization, separation and purification of calcium fluoride sludge: by adding fluorine-containing waste acid and clean water to calcium fluoride sludge, stirring and dissolving to form a mixed solution, by using a pH regulator to adjust the pH of the mixed solution, calcium fluoride and calcium fluorosilicate are separated in turn, by drying the separated calcium fluoride to obtain dry calcium fluoride, and using a sulfuric acid method to react the dry calcium fluoride to generate anhydrous hydrogen fluoride, by drying the separated calcium fluorosilicate to obtain a calcium fluorosilicate by-product, by reacting the residual liquid formed after separating calcium fluoride and calcium fluorosilicate from the mixed solution, and then filtering to obtain a potassium fluorosilicate by-product and an acid solution, thereby solving the problem that fluoride-containing sludge is difficult to handle, which not only causes a waste of resources but also causes pollution to the environment.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for comprehensive utilization, separation and purification of calcium fluoride sludge comprises the following steps:

[0007] Step 1: Purification of calcium fluoride with waste acid: adding fluorine-containing waste acid and clean water to calcium fluoride sludge, stirring and dissolving to form a mixed solution;

[0008] Step 2: Adjusting pH value and separation: Using a pH adjuster to adjust the pH of the mixed solution, and separating calcium fluoride and calcium fluorosilicate in turn;

[0009] Step 3: drying the separated calcium fluoride to obtain dry calcium fluoride, and using a sulfuric acid method to react the dry calcium fluoride to generate anhydrous hydrogen fluoride, and adding the anhydrous hydrogen fluoride or residual gas into water or spraying with water to absorb it to produce aqueous hydrofluoric acid;

[0010] Step 4: drying the separated calcium fluorosilicate to obtain a calcium fluorosilicate by-product;

[0011] Step 5: reacting the residual liquid formed after separating calcium fluoride and calcium fluorosilicate from the mixed solution, and then filtering to obtain potassium fluorosilicate byproduct and acid solution, and evaporating the potassium fluorosilicate to obtain a solid byproduct.

[0012] As a further solution of the present invention: the calcium fluoride sludge in step one comes from calcium fluoride sludge produced in the production process of semiconductor, panel and photovoltaic industries, and the fluorine-containing waste acid comes from waste acid produced in the production process of semiconductor, panel and photovoltaic industries.

[0013] As a further solution of the present invention: the usage ratio of the calcium fluoride sludge, fluorine-containing waste acid and clean water in step 1 is 1kg:2.5-3kg:2-20kg.

[0014] As a further solution of the present invention: the pH adjusting agent in step 2 is a hydrochloric acid solution and a sodium hydroxide solution, the mass fraction of the hydrochloric acid solution is 20-32%, and the mass fraction of the sodium hydroxide solution is 20-40%.

[0015] As a further solution of the present invention: the specific process of adjusting the pH value and separating in step 2 is as follows:

[0016] The pH of the mixed solution is adjusted to 3-4.5 using a hydrochloric acid solution, and then centrifuged using a centrifuge, and the precipitate is washed with clean water to separate calcium fluoride;

[0017] The pH of the mixed solution is adjusted to 5.5-8 using a sodium hydroxide solution, and then centrifuged using a centrifuge. The precipitate is washed with clean water to separate the calcium fluorosilicate.

[0018] As a further solution of the present invention: the calcium fluoride drying condition in step 3 is to use flash drying equipment for drying until the moisture content is less than 0.2%.

[0019] As a further solution of the present invention: the specific process of the dried calcium fluoride in step 3 to generate anhydrous hydrogen fluoride is as follows:

[0020] Add dry calcium fluoride and sulfuric acid to the rotary reactor, react at a reaction temperature of 200-300°C, introduce the hydrogen fluoride gas produced by the reaction into the condensation system, control the condensation temperature to -20-0°C, condense the hydrogen fluoride gas to form anhydrous hydrogen fluoride, the chemical reaction formula is as follows: CaF2+H2SO4→2HF+CaSO4, introduce the residual gas into the spray tower system, control the temperature of the spray water in the spray tower system to 5-20°C, the spray water absorbs the hydrogen fluoride gas to form aqueous hydrofluoric acid, the chemical reaction formula is as follows: HF (g) +H2O→HF (eq) .

[0021] As a further solution of the present invention: the usage ratio of the dry calcium fluoride and sulfuric acid in step 3 is 1kg:1.3-1.7kg, and the mass fraction of the sulfuric acid is 98.3%.

[0022] As a further solution of the present invention: the calcium fluorosilicate drying condition in step 4 is to use flash drying equipment for drying until the moisture content is less than 0.2%.

[0023] As a further solution of the present invention: the specific process of the residual liquid in step 5 reacting is as follows:

[0024] Potassium chloride is added to the residual liquid, and the reaction is stirred at a temperature of 50-60°C for 1-2 hours, and then vacuum filtered, the filtrate is collected to obtain acid solution, the filter cake is washed with clean water and then dried to obtain potassium fluorosilicate by-product, and the chemical reaction formula is as follows: H2S i F6+2KCl=K2S i F6↓+2HCl.

[0025] As a further solution of the present invention: the filter cake drying condition is to use flash drying equipment for drying until the moisture content is less than 0.2%; the usage ratio of the residual liquid and potassium chloride is 1kg:75-115g.

[0026] Beneficial effects of the present invention:

[0027] The invention discloses a method for comprehensive utilization, separation and purification of calcium fluoride sludge, comprising the steps of adding fluorine-containing waste acid and clean water to the calcium fluoride sludge, stirring and dissolving the mixture to form a mixed solution, adjusting the pH of the mixed solution by using a pH regulator, separating calcium fluoride and calcium fluorosilicate in sequence, drying the separated calcium fluoride to obtain dry calcium fluoride, and reacting the dry calcium fluoride to generate anhydrous hydrogen fluoride by using a sulfuric acid method, drying the separated calcium fluorosilicate to obtain a calcium fluorosilicate byproduct, reacting the residual liquid formed after separating calcium fluoride and calcium fluorosilicate from the mixed solution, and filtering the residual liquid to obtain a potassium fluorosilicate byproduct and an acid solution;

[0028] The method for treating calcium fluoride sludge is different from the traditional method for treating calcium fluoride sludge. Instead, the calcium fluoride sludge is separated and purified to produce high-purity calcium fluoride powder, calcium fluorosilicate and potassium fluorosilicate. The purity of calcium fluorosilicate can be purified to more than 95%, and the purity of potassium fluorosilicate can be industrial-grade products with a purity of more than 99.5%. Part of the fluorine-containing waste acid is used in the purification process. While the fluorine-containing waste acid is comprehensively utilized, the generation of secondary pollution is also reduced, creating economic benefits.

[0029] The method uses fluorine-containing waste acid to treat calcium fluoride sludge. Because the calcium fluoride sludge has been placed for too long and the sludge is alkaline, a large amount of calcium oxide remaining in the sludge absorbs carbon dioxide in the air, thereby forming calcium carbonate. The calcium carbonate is dissolved by the hydrofluoric acid in the fluorine-containing waste acid, and the following reaction occurs: CaCO3+2HF=CaF2+CO2↑+H2O. At the same time, a large amount of calcium fluorosilicate is dissolved into the aqueous solution. The calcium ions and hydrofluoric acid form calcium fluoride, and the fluorosilicic acid is dissolved in the water. Then, the pH is adjusted to make the substances in the mixed solution Precipitation is performed to obtain high-purity calcium fluoride, and the calcium fluoride is reacted with the sulfuric acid method to generate anhydrous hydrogen fluoride, wherein the hydrogen fluoride gas that has not been completely condensed dissolves in water to form aqueous hydrofluoric acid, and the anhydrous hydrogen fluoride and aqueous hydrofluoric acid can be reused in the production processes of the semiconductor, panel, and photovoltaic industries, and calcium fluorosilicate can be separated. The calcium fluorosilicate byproduct has high purity and can be sold directly to generate income. Finally, potassium chloride is used to treat the residual liquid, which contains a large amount of fluorosilicic acid. The fluorosilicic acid and potassium chloride react as follows: H2S i F6 + 2KCl = K2S i F6↓ + 2HCl, thereby fully converting the fluorosilicic acid into acid solution and potassium fluorosilicate for recovery. The acid solution can be used as a pH adjuster to adjust the pH of the mixed solution, and the potassium fluorosilicate byproduct has high purity and can be sold directly to generate income.

[0030] The method can comprehensively utilize fluorine-containing waste acid and calcium fluoride sludge at the same time, and separate and purify the useful substances therein for reuse. The obtained hydrofluoric acid and acid solution reduce the production cost of the enterprise, and the obtained calcium fluorosilicate and potassium fluorosilicate can be sold directly, have a high market value, and have significant economic benefits. The method not only improves resource utilization and reduces the impact on the environment, but is also easy to trial and promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described below in conjunction with the accompanying drawings.

[0032] Figure 1 The present invention discloses a process flow chart of a method for comprehensive utilization, separation and purification of calcium fluoride sludge. DETAILED DESCRIPTION

[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Embodiment 1:

[0035] See also Figure 1 As shown, this embodiment is a method for comprehensive utilization, separation and purification of calcium fluoride sludge, comprising the following steps:

[0036] Step 1, waste acid purification of calcium fluoride: add fluorine-containing waste acid and clean water to calcium fluoride sludge, stir and dissolve, and form a mixed solution; the calcium fluoride sludge comes from calcium fluoride sludge generated in the production process of semiconductor, panel, and photovoltaic industries, and the fluorine-containing waste acid comes from waste acid generated in the production process of semiconductor, panel, and photovoltaic industries; the usage ratio of the calcium fluoride sludge, fluorine-containing waste acid, and clean water is 1kg:2.5kg:2g;

[0037] Step 2, adjusting pH value and separation: using a pH adjuster to adjust the pH of the mixed solution, the pH adjuster is a hydrochloric acid solution and a sodium hydroxide solution, and calcium fluoride and calcium fluorosilicate are separated in turn; the specific process is as follows:

[0038] The pH value of the mixed solution is adjusted to 4.5 using a 20% hydrochloric acid solution, and then centrifuged using a centrifuge, and the precipitate is washed with clean water to separate calcium fluoride;

[0039] The pH value of the mixed solution is adjusted to 5.5 using a sodium hydroxide solution with a mass fraction of 20%, and then centrifuged using a centrifuge, and the precipitate is washed with clean water to separate the calcium fluorosilicate;

[0040] Step 3: drying the separated calcium fluoride, wherein the calcium fluoride is dried using a flash drying device until the water content is less than 0.2% to obtain dry calcium fluoride, and reacting the dry calcium fluoride to generate anhydrous hydrogen fluoride using a sulfuric acid method; the specific process of the dry calcium fluoride to generate anhydrous hydrogen fluoride is as follows:

[0041] Adding dry calcium fluoride and sulfuric acid into a rotary reactor, reacting at a reaction temperature of 200°C, introducing hydrogen fluoride gas generated by the reaction into a condensation system, controlling the condensation temperature to be 0°C, condensing the hydrogen fluoride gas to form anhydrous hydrogen fluoride, introducing the residual gas into a spray tower system, controlling the temperature of the spray water in the spray tower system to be 5°C, and the spray water absorbs the hydrogen fluoride gas to form aqueous hydrofluoric acid; the usage ratio of the dry calcium fluoride and sulfuric acid is 1kg:1.3kg, and the mass fraction of the sulfuric acid is 98.3%;

[0042] Step 4: drying the separated calcium fluorosilicate, wherein the calcium fluorosilicate is dried using a flash drying device until the moisture content is less than 0.2%, to obtain a calcium fluorosilicate byproduct;

[0043] Step 5: react the residual liquid formed after separating calcium fluoride and calcium fluorosilicate from the mixed solution, and then filter to obtain potassium fluorosilicate byproduct and acid solution; the specific process is as follows:

[0044] Potassium chloride was added to the residual liquid, and the reaction was stirred at a temperature of 50°C for 1 hour, followed by vacuum filtration, and the filtrate was collected to obtain acid solution. The filter cake was washed with clean water and then dried. The filter cake drying condition was to use a flash drying device for drying until the water content was less than 0.2%, and potassium fluorosilicate by-product was obtained.

[0045] Embodiment 2:

[0046] See also Figure 1 As shown, this embodiment is a method for comprehensive utilization, separation and purification of calcium fluoride sludge, comprising the following steps:

[0047] Step 1, waste acid purification of calcium fluoride: add fluorine-containing waste acid and clean water to calcium fluoride sludge, stir and dissolve, and form a mixed solution; the calcium fluoride sludge comes from calcium fluoride sludge generated in the production process of semiconductor, panel, and photovoltaic industries, and the fluorine-containing waste acid comes from waste acid generated in the production process of semiconductor, panel, and photovoltaic industries; the usage ratio of the calcium fluoride sludge, fluorine-containing waste acid, and clean water is 1kg:2.8kg:11kg;

[0048] Step 2, adjusting pH value and separation: using a pH adjuster to adjust the pH of the mixed solution, the pH adjuster is a hydrochloric acid solution and a sodium hydroxide solution, and calcium fluoride and calcium fluorosilicate are separated in turn; the specific process is as follows:

[0049] The pH value of the mixed solution is adjusted to 4 using a hydrochloric acid solution with a mass fraction of 26%, and then centrifuged using a centrifuge, and the precipitate is washed with clean water to separate calcium fluoride;

[0050] The pH value of the mixed solution is adjusted to 6.5 using a sodium hydroxide solution with a mass fraction of 30%, and then centrifuged using a centrifuge, and the precipitate is washed with clean water to separate the calcium fluorosilicate;

[0051] Step 3: drying the separated calcium fluoride, wherein the calcium fluoride is dried using a flash drying device until the water content is less than 0.2% to obtain dry calcium fluoride, and reacting the dry calcium fluoride to generate anhydrous hydrogen fluoride using a sulfuric acid method; the specific process of the dry calcium fluoride to generate anhydrous hydrogen fluoride is as follows:

[0052] Adding dry calcium fluoride and sulfuric acid into a rotary reactor, reacting at a reaction temperature of 250°C, introducing hydrogen fluoride gas generated by the reaction into a condensation system, controlling the condensation temperature to -10°C, condensing the hydrogen fluoride gas to form anhydrous hydrogen fluoride, introducing the residual gas into a spray tower system, controlling the water temperature of the spray water in the spray tower system to 12°C, and the spray water absorbs the hydrogen fluoride gas to form aqueous hydrofluoric acid; the usage ratio of the dry calcium fluoride and sulfuric acid is 1kg:1.5kg, and the mass fraction of the sulfuric acid is 98.3%;

[0053] Step 4: drying the separated calcium fluorosilicate, wherein the calcium fluorosilicate is dried using a flash drying device until the moisture content is less than 0.2%, to obtain a calcium fluorosilicate byproduct;

[0054] Step 5: react the residual liquid formed after separating calcium fluoride and calcium fluorosilicate from the mixed solution, and then filter to obtain potassium fluorosilicate byproduct and acid solution; the specific process is as follows:

[0055] Potassium chloride was added to the residual liquid, and the reaction was stirred at a temperature of 55°C for 1.5 hours, and then vacuum filtered to collect the filtrate to obtain acid solution. The filter cake was washed with clean water and then dried. The filter cake drying condition was to use a flash drying device for drying until the water content was less than 0.2% to obtain potassium fluorosilicate by-product; the amount ratio of the residual liquid to potassium chloride was 1kg:95g.

[0056] Embodiment 3:

[0057] See also Figure 1 As shown, this embodiment is a method for comprehensive utilization, separation and purification of calcium fluoride sludge, comprising the following steps:

[0058] Step 1, waste acid purification of calcium fluoride: add fluorine-containing waste acid and clean water to calcium fluoride sludge, stir and dissolve, and form a mixed solution; the calcium fluoride sludge comes from calcium fluoride sludge generated in the production process of semiconductor, panel, and photovoltaic industries, and the fluorine-containing waste acid comes from waste acid generated in the production process of semiconductor, panel, and photovoltaic industries; the usage ratio of the calcium fluoride sludge, fluorine-containing waste acid, and clean water is 1kg:3kg:20kg;

[0059] Step 2, adjusting pH value and separation: using a pH adjuster to adjust the pH of the mixed solution, the pH adjuster is a hydrochloric acid solution and a sodium hydroxide solution, and calcium fluoride and calcium fluorosilicate are separated in turn; the specific process is as follows:

[0060] The pH value of the mixed solution is adjusted to 3 using a hydrochloric acid solution with a mass fraction of 32%, and then centrifuged using a centrifuge, and the precipitate is washed with clean water to separate calcium fluoride;

[0061] The pH value of the mixed solution is adjusted to 8 using a sodium hydroxide solution with a mass fraction of 40%, and then centrifuged using a centrifuge, and the precipitate is washed with clean water to separate calcium fluorosilicate;

[0062] Step 3: drying the separated calcium fluoride, wherein the calcium fluoride is dried using a flash drying device until the water content is less than 0.2% to obtain dry calcium fluoride, and reacting the dry calcium fluoride to generate anhydrous hydrogen fluoride using a sulfuric acid method; the specific process of the dry calcium fluoride to generate anhydrous hydrogen fluoride is as follows:

[0063] Adding dry calcium fluoride and sulfuric acid into a rotary reactor, reacting at a reaction temperature of 300°C, introducing hydrogen fluoride gas generated by the reaction into a condensation system, controlling the condensation temperature to -20°C, condensing the hydrogen fluoride gas to form anhydrous hydrogen fluoride, introducing the residual gas into a spray tower system, controlling the water temperature of the spray water in the spray tower system to 20°C, and the spray water absorbs the hydrogen fluoride gas to form aqueous hydrofluoric acid; the usage ratio of the dry calcium fluoride and sulfuric acid is 1kg:1.7kg, and the mass fraction of the sulfuric acid is 98.3%;

[0064] Step 4: drying the separated calcium fluorosilicate, wherein the calcium fluorosilicate is dried using a flash drying device until the moisture content is less than 0.2%, to obtain a calcium fluorosilicate byproduct;

[0065] Step 5: react the residual liquid formed after separating calcium fluoride and calcium fluorosilicate from the mixed solution, and then filter to obtain potassium fluorosilicate byproduct and acid solution; the specific process is as follows:

[0066] Potassium chloride is added to the residual liquid, and the reaction is stirred at a temperature of 60°C for 2 hours, followed by vacuum filtration, and the filtrate is collected to obtain acid solution. The filter cake is washed with clean water and then dried. The filter cake drying condition is to use a flash drying device for drying until the moisture content is less than 0.2% to obtain potassium fluorosilicate by-product; the usage ratio of the residual liquid to potassium chloride is 1kg:115g.

[0067] The calcium fluoride sludge in Examples 1-3 was tested, and the test results are shown in the following table:

[0068] Element <![CDATA[H2O]]> CaF <![CDATA[CaSiF6]]> <![CDATA[CaCO3]]> other content,% 25.54 58.65 8.69 3.95 3.17

[0069] The fluorine-containing waste acid in Examples 1-3 was tested, and the test results are shown in the following table:

[0070] Appearance Acidity (HCl meter) m(HF),% <![CDATA[m(H2SiF6),%]]> <![CDATA[m(SO4 2- ),%]]> <![CDATA[m(Cl - ),%]]> Colorless and transparent 18.56 4.96 9.25 4.53 0.10

[0071] The products in Examples 1-3 were tested, and the test results are shown in the following table:

[0072] sample Example 1 Example 2 Example 3 Purity of anhydrous hydrogen fluoride, % 99.67 99.75 99.81 Calcium fluorosilicate purity, % 95.58 95.91 96.35 Potassium fluorosilicate purity, % 99.51 99.63 99.72

[0073] Referring to the data in the above table, it can be known that after the comprehensive utilization of calcium fluoride sludge by the method of the present invention, high-purity anhydrous hydrogen fluoride, calcium fluorosilicate and potassium fluorosilicate can be recovered to create economic benefits.

[0074] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0075] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A method for comprehensive utilization, separation and purification of calcium fluoride sludge, characterized in that: The following steps are involved: Step 1: Purification of calcium fluoride with waste acid: adding fluorine-containing waste acid and clean water to calcium fluoride sludge, stirring and dissolving to form a mixed solution; Step 2: Adjusting pH value and separation: Using a pH adjuster to adjust the pH of the mixed solution, and separating calcium fluoride and calcium fluorosilicate in turn; The specific process of adjusting pH value and separation is as follows: The pH of the mixed solution is adjusted to 3-4.5 using a hydrochloric acid solution, and then centrifuged using a centrifuge, and the precipitate is washed with clean water to separate calcium fluoride; The pH of the mixed solution is adjusted to 5.5-8 using a sodium hydroxide solution, and then centrifuged using a centrifuge, and the precipitate is washed with clean water to separate the calcium fluorosilicate; Step 3: drying the separated calcium fluoride to obtain dry calcium fluoride, and using a sulfuric acid method to react the dry calcium fluoride to generate anhydrous hydrogen fluoride, and adding the anhydrous hydrogen fluoride or residual gas into water or spraying with water to absorb it to produce aqueous hydrofluoric acid; The specific process of drying calcium fluoride to generate anhydrous hydrogen fluoride is as follows: Adding dry calcium fluoride and sulfuric acid into a rotary reactor, reacting at a reaction temperature of 200-300° C., introducing hydrogen fluoride gas generated by the reaction into a condensation system, controlling the condensation temperature to be -20-0° C., condensing the hydrogen fluoride gas to form anhydrous hydrogen fluoride, introducing the residual gas into a spray tower system, controlling the temperature of spray water in the spray tower system to be 5-20° C., and the spray water absorbs the hydrogen fluoride gas to form aqueous hydrofluoric acid; Step 4: drying the separated calcium fluorosilicate to obtain a calcium fluorosilicate by-product; Step 5: reacting the residual liquid formed after separating calcium fluoride and calcium fluorosilicate from the mixed solution, and then filtering to obtain potassium fluorosilicate byproduct and acid solution, and evaporating the potassium fluorosilicate to obtain a solid byproduct; The specific process of the residual liquid reacting is as follows: Potassium chloride is added to the residual liquid, and the reaction is stirred at a temperature of 50-60° C. for 1-2 hours, followed by vacuum filtration, and the filtrate is collected to obtain an acid solution. The filter cake is washed with clean water and then dried to obtain potassium fluorosilicate by-product; the filter cake drying condition is to use a flash drying device for drying until the moisture content is less than 0.2%.

2. A method for comprehensive utilization, separation and purification of calcium fluoride sludge according to claim 1, characterized in that: The calcium fluoride sludge in step one comes from calcium fluoride sludge produced in the production processes of semiconductor, panel and photovoltaic industries, and the fluorine-containing waste acid comes from waste acid produced in the production processes of semiconductor, panel and photovoltaic industries.

3. The method for comprehensive utilization, separation and purification of calcium fluoride sludge according to claim 1, characterized in that: The usage ratio of the calcium fluoride sludge, fluorine-containing waste acid and clean water in step 1 is 1kg: 2.5-3kg: 2-20kg.

4. The method for comprehensive utilization, separation and purification of calcium fluoride sludge according to claim 1, characterized in that: The pH regulator in step 2 is hydrochloric acid solution and sodium hydroxide solution, the mass fraction of the hydrochloric acid solution is 20-32%, and the mass fraction of the sodium hydroxide solution is 20-40%.

5. The method for comprehensive utilization, separation and purification of calcium fluoride sludge according to claim 1, characterized in that: The calcium fluoride drying condition in step 3 is to use flash drying equipment to dry until the moisture content is less than 0.2%.

6. The method for comprehensive utilization, separation and purification of calcium fluoride sludge according to claim 1, characterized in that: The usage ratio of the dry calcium fluoride and sulfuric acid in step 3 is 1kg:1.3-1.7kg, and the mass fraction of the sulfuric acid is 98.3%.

7. The method for comprehensive utilization, separation and purification of calcium fluoride sludge according to claim 1, characterized in that: The calcium fluorosilicate drying condition in step 4 is to use flash drying equipment for drying until the moisture content is less than 0.2%.

8. The method for comprehensive utilization, separation and purification of calcium fluoride sludge according to claim 1, characterized in that: The usage ratio of the residual liquid and potassium chloride is 1kg:75-115g.

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