A method for producing hydrogen fluoride from fluosilicic acid

Abstract

The application belongs to the technical field of inorganic chemical industry, and discloses a method for producing hydrogen fluoride from fluosilicic acid, which adopts a composite mineral catalyst composed of gamma-Al2O3 and diatomite to catalyze the reaction between fluosilicic acid and sulfuric acid at 120 DEG C to 160 DEG C, wherein the diatomite serves as a porous template for calcium sulfate crystallization, guides the generation of a loose and porous Al2O3-diatomite-calcium sulfate composite solid-phase product, and avoids mass transfer blockage; the gamma-Al2O3 provides acidic sites to accelerate the reaction. The obtained by-product can be directly used as a building material retarder, a soil conditioner or a desulfurizer, so that resource utilization is realized. The method reduces energy consumption and equipment cost, and guarantees continuous and stable operation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of inorganic chemical industry and relates to a method for producing hydrogen fluoride from fluosilicic acid. BACKGROUND

[0002] Hydrogen fluoride, as a basic chemical raw material, plays an irreplaceable strategic role in high-end manufacturing fields such as refrigerants, fluorine-containing polymers, electronic-grade hydrofluoric acid and pharmaceutical intermediates. Today, the global demand for high-purity fluorine chemicals is rising, and developing an efficient, clean and low-energy hydrogen fluoride preparation method has become a key direction for the upgrading of the fluorine chemical industry.

[0003] However, with the deepening of the concept of green manufacturing and the increasingly stringent environmental protection regulations, the inherent shortcomings of the traditional high-temperature process are becoming more and more obvious, especially in terms of reaction stability and by-product disposal, which exposes deep-seated problems. The calcium sulfate generated during the reaction is prone to crystal transformation and particle agglomeration in a high-temperature environment, forming a dense and hard block, which in turn encapsulates unreacted fluosilicic acid or catalyst particles, causing mass transfer channel blockage and reaction interface inactivity, ultimately leading to a significant decrease in reaction rate or even stopping midway. This not only reduces the space-time yield and raw material conversion rate of hydrogen fluoride, but also requires frequent shutdown and cleaning of the reactor by the operator, seriously affecting the continuous operation of the device. SUMMARY

[0004] To achieve the above-mentioned purposes, the application provides a method for producing hydrogen fluoride from fluosilicic acid, which introduces a composite mineral catalyst system to effectively inhibit the densification and agglomeration of calcium sulfate by-products while reducing the reaction temperature, and simultaneously realizes the structure and function of calcium sulfate, thereby completely solving the reaction interruption risk and solid waste disposal problems existing in the traditional high-temperature process while ensuring high hydrogen fluoride yield and raw material conversion rate.

[0005] The core of the application is to construct a composite mineral catalyst composed of alumina (Al2O3) and diatomite. This catalyst not only provides acidic catalytic sites to accelerate the kinetics of the metathesis reaction between fluosilicic acid and sulfuric acid, but also uses the unique porous framework structure of diatomite as a physical template and dispersion carrier for calcium sulfate crystallization, guiding the in-situ formation of a loose, porous and high specific surface area composite solid phase product during the reaction, thereby avoiding the mass transfer blockage and reaction interface passivation problems caused by calcium sulfate sintering in the traditional process. On this basis, the composite solid phase product, due to its controllable micro-morphology and chemical composition, can be directly used as a functional filler or slow-release calcium and sulfur source for building materials, soil improvement or flue gas desulfurization, etc., achieving the resource-based high-value utilization of by-products.

[0006] The method according to the application comprises the following steps:

[0007] Firstly, an aqueous fluosilicic acid solution with a mass concentration of 15% to 30% is mixed with concentrated sulfuric acid with a concentration of 93% to 98% at a molar ratio of SiF6 2- in the fluosilicic acid to H + in the sulfuric acid of 1:4 to 1:6 to form a reaction precursor solution. The fluosilicic acid is derived from the by-product fluosilicic acid mother liquor generated in the wet-process phosphoric acid production process, which is directly used after removing suspended impurities through preliminary clarification and filtration without additional purification.

[0008] Secondly, a composite mineral catalyst is added to the reaction precursor solution, and the addition amount is 3% to 8% of the mass of the fluosilicic acid. The composite mineral catalyst is composed of γ-Al2O3 and natural diatomite at a mass ratio of 1:2 to 1:4. Among them, the specific surface area of γ-Al2O3 is not less than 180 m² / g, the pore volume is 0.4 to 0.6 cm³ / g, and the average pore size is 5 to 8 nm, which can effectively activate the Si-F bond in the fluosilicic acid molecule and promote the replacement reaction of F + to H - .

[0009] The diatomite is natural diatomite treated by calcination at 500°C for 2 hours, and its main mineral phase is amorphous silicon dioxide with a SiO2 content of not less than 85%, a bulk density of 0.3 to 0.5 g / cm³, a porosity of more than 70%, and an average pore size of 0.5 to 2 μm, having a three-dimensional through micron-level pore network structure.

[0010] The preparation method of the composite mineral catalyst is as follows: γ-Al2O3 powder and diatomite powder are dry mixed in a high-speed mixer at a set ratio for 30 minutes, then deionized water is added to form a slurry with a solid content of 40%, which is aged at 60°C for 2 hours, then spray dried into microspheres with a particle size of 100 to 300 μm, and finally calcined at 550°C in air for 3 hours to obtain the final catalyst. The catalyst exists in a solid phase suspension state in the reaction system and is insoluble in the reaction solution, and can be recycled and reused after the reaction is completed through solid-liquid separation.

[0011] Subsequently, the reaction mixture containing the composite mineral catalyst is placed in a reaction kettle with stirring and gas discharge device, and the reaction is carried out at a temperature range of 120°C to 160°C for 1.5 to 3 hours. Continuous stirring is carried out during the reaction at a stirring speed of 200 to 400 rpm to ensure uniform dispersion of the catalyst particles and effective contact of the gas-liquid-solid three-phase interface. The hydrogen fluoride gas generated in the reaction is dehydrated by condensation, then captured by two-stage cold traps (-20°C and -78°C) to obtain anhydrous hydrogen fluoride product with a purity of not less than 99.5%.

[0012] The key is that the calcium sulfate generated in the reaction process is not precipitated in the form of free crystals, but is crystallized in situ inside and on the surface of the porous framework of diatomite. Due to the space confinement effect of the diatomite channel and the weak adsorption of the surface hydroxyl group to Ca2+, the growth of calcium sulfate crystals is physically constrained and cannot form large-size dense particles, but is uniformly embedded in the diatomite pores in the form of nano to sub-micron grains, and finally forms a kind of Al2O3-diatomite-calcium sulfate ternary composite solid phase product. The X-ray diffraction pattern of the product shows that the calcium sulfate mainly exists in the form of semi-hydrated gypsum (CaS4·0.5H2O) or anhydrous gypsum (CaS4), and no high-temperature sintered phase such as anhydrite (CaS4-II) is detected. Scanning electron microscope observation shows that the composite product retains the original porous framework structure of diatomite, the pores are not completely blocked, and the specific surface area is maintained at 20 to 40 m² / g, which is much higher than that of calcium sulfate obtained by traditional process (the specific surface area is usually less than 5 m² / g).

[0013] Further, the composite solid phase product can be directly used as a functional material after water washing and drying. Typical applications include: as a cement retarder, the dosage is 0.5% to 2% of the mass of cement, which can effectively adjust the setting time without affecting the strength development; as a soil conditioner, used for calcium and sulfur supplementation in acidic soil, its slow-release characteristic can avoid rapid leaching of nutrients; or as a flue gas desulfurization agent, regenerated into calcium sulfate at 600°C to 800°C by reacting with SO2, realizing recycling.

[0014] As a preferred embodiment of the present application, the reaction temperature is controlled at 140°C, the reaction time is 2 hours, the concentration of fluosilicic acid is 20%, the concentration of sulfuric acid is 96%, the addition amount of catalyst is 5% of the mass of fluosilicic acid, and the mass ratio of γ-Al2O3 to diatomite in the catalyst is 1:3. Under this condition, the conversion rate of fluorine in fluosilicic acid reaches 98.7%, the hydrogen fluoride space-time yield is 1.85 kg / (L·h), and the reactor continuously runs for 120 hours without caking or pressure drop rising phenomenon.

[0015] As another preferred embodiment of the present application, the diatomite is surface modified by silane coupling agent KH-550 before compounding: the diatomite is dispersed in an ethanol-water mixed solvent, 2% of KH-550 based on the mass of diatomite is added, and the reaction is carried out at 60°C for 4 hours, and then the product is filtered and dried for use. The modification enhances the interfacial compatibility of the diatomite surface with the calcium sulfate crystals, further inhibits crystal agglomeration, and makes the specific surface area of the composite product increase to more than 45 m² / g, and the pore distribution is more uniform.

[0016] Compared with the traditional high-temperature process, the reaction temperature is reduced from above 250 DEG C to below 160 DEG C, the energy consumption is reduced by about 40%, the hydrogen fluoride yield is increased from 85% to 90% to above 98%, the by-product is changed from the compact solid waste needing landfill disposal to the functional material which can be resourcefully utilized, and the closed loop utilization of calcium and sulfur elements is realized. In addition, since the reaction is carried out under mild conditions, the equipment material can use 316L stainless steel instead of the traditional required hastelloy, and the investment cost is greatly reduced.

[0017] Compared with the prior art, the beneficial effects of the present application are:

[0018] 1. The technical scheme of the present application realizes triple synergistic effect in reaction mechanism: firstly, the acid sites provided by gamma-Al2O3 reduce the activation energy of the metathesis reaction, so that the reaction can still be carried out efficiently at low temperature; secondly, the porous structure of diatomite acts as a nano-reactor for calcium sulfate crystallization, and regulates the crystal nucleation and growth kinetics through space confinement effect to inhibit its densification; thirdly, the interface interaction between Al2O3 and diatomite under high-temperature hydrothermal environment may form Al-O-Si bonding structure, further stabilizing the micro-morphology of the composite product and preventing its structure collapse in subsequent application.

[0019] 2. The present application synchronously optimizes the fluorosilicic acid hydrogen fluoride production process from the two dimensions of reaction kinetics and product phase state by constructing Al2O3-diatomite composite mineral catalyst system, realizes efficient, continuous and clean production of hydrogen fluoride under mild conditions of 120 DEG C to 160 DEG C, and converts traditional solid waste into high-value functional materials, which completely solves the three technical bottlenecks of low reaction efficiency, unstable operation and difficult solid waste disposal in the prior art, and provides a new technical path for green and high-value utilization of fluorine resources. DETAILED DESCRIPTION

[0020] A method for producing hydrogen fluoride from fluorosilicic acid, by constructing a composite mineral catalyst system composed of gamma-alumina and diatomite, under mild reaction conditions of 120 DEG C to 160 DEG C, the efficient generation of hydrogen fluoride and the structural functionalization of calcium sulfate by-product are realized synchronously, so as to completely avoid the risk of reaction interruption caused by calcium sulfate sintering in the traditional high-temperature process, and the by-product is converted into a functional material that can be resourcefully utilized. The core of the method is to utilize the acid catalytic activity of gamma-alumina to accelerate the metathesis reaction kinetics between fluorosilicic acid and sulfuric acid, and at the same time, to use the three-dimensional through-porous framework of diatomite as a physical template and dispersion carrier for calcium sulfate crystallization, to regulate the crystal nucleation and growth behavior through space confinement effect, to inhibit its densification and agglomeration, and finally to form a loose, high specific surface area Al2O3-diatomite-calcium sulfate ternary composite solid phase product.

[0021] The technical solutions of the present application will be described in detail below in combination with specific examples and comparative examples to ensure that those skilled in the art can fully understand and implement the present application.

[0022] Example 1: Preferred process conditions

[0023] Fluorosilicic acid: pure product, mass concentration 20%;

[0024] Sulfuric acid: mass concentration 96%, filtered through a 0.2 μm polytetrafluoroethylene membrane (Fe 3+ <10 mg / L, As <1 mg / L);

[0025] SiF6 2- and H + Molar ratio: 1:5;

[0026] Composite mineral catalyst: mass ratio of γ-Al2O3 to diatomite 1:3, diatomite unmodified (calcined at 500°C for 2 hours, SiO2≥85%), amount added 5% of the mass of the fluorosilicic acid;

[0027] Reaction conditions: temperature 140°C, time 2 hours, stirring speed 300 rpm;

[0028] Product treatment: hydrogen fluoride trapped in a -20°C ethylene glycol / water cold trap and a -78°C dry ice / acetone cold trap;

[0029] Performance data: fluorine conversion rate 98.7%, no caking during the reaction process, specific surface area of the composite product 32 m² / g, hydrogen fluoride purity 99.6%, by-product fluorine residue <50 mg / kg, which can be used as a cement retarder (doping amount 0.5%-2%).

[0030] Example 2: Adjusting the composition ratio of the catalyst

[0031] Fluorosilicic acid: pure product, mass concentration 20%;

[0032] Sulfuric acid: mass concentration 96%, filtered in the same way as in Example 1;

[0033] SiF6 2- and H + Molar ratio: 1:5;

[0034] Composite mineral catalyst: mass ratio of γ-Al2O3 to diatomite 1:2, diatomite unmodified, amount added 5% of the mass of the fluorosilicic acid;

[0035] Reaction conditions: temperature 140°C, time 2 hours, stirring speed 300 rpm;

[0036] Product treatment: same as in Example 1;

[0037] Performance data: fluorine conversion rate 98.1%, no caking during reaction, specific surface area of composite product 28 m2 / g, hydrogen fluoride purity 99.5%, by-product can be used as soil conditioner.

[0038] Example 3: adjusting raw material concentration and reaction temperature

[0039] Fluosilicic acid: pure product, mass concentration 25%;

[0040] Sulfuric acid: mass concentration 98%, filtration treatment same as example 1;

[0041] SiF6 2- and H + Molar ratio: 1:6;

[0042] Composite mineral catalyst: mass ratio of γ-Al2O3 to diatomite 1:3, diatomite unmodified, amount added 6% of mass of fluosilicic acid;

[0043] Reaction conditions: temperature 150°C, time 2.5 hours, stirring speed 350 rpm;

[0044] Product treatment: same as example 1;

[0045] Performance data: fluorine conversion rate 98.3%, no caking during reaction, specific surface area of composite product 35 m2 / g, hydrogen fluoride purity 99.6%, by-product can be used as flue gas desulfurizer.

[0046] Example 4: reducing catalyst amount and reaction temperature

[0047] Fluosilicic acid: pure product, mass concentration 15%;

[0048] Sulfuric acid: mass concentration 93%, filtration treatment same as example 1;

[0049] SiF6 2- and H + Molar ratio: 1:4;

[0050] Composite mineral catalyst: mass ratio of γ-Al2O3 to diatomite 1:3, diatomite unmodified, amount added 3% of mass of fluosilicic acid;

[0051] Reaction conditions: temperature 120°C, time 3 hours, stirring speed 250 rpm;

[0052] Product treatment: same as example 1;

[0053] Performance data: fluorine conversion rate 97.8%, no caking during reaction, specific surface area of composite product 25 m2 / g, hydrogen fluoride purity 99.5%, by-product can be used as cement retarder.

[0054] Example 5: diatomite surface modification:

[0055] Fluorosilicic acid: pure product, mass concentration 20%;

[0056] Sulfuric acid: 96% by mass, filtered as in Example 1;

[0057] SiF6 2- With H + Molar ratio: 1:5;

[0058] Composite mineral catalyst: γ-Al2O3 to diatomaceous earth in a mass ratio of 1:3, diatomaceous earth modified with KH-550 (reacted in ethanol-water solvent at 60℃ for 4 hours, the amount of KH-550 added is 2% of the mass of diatomaceous earth), and the amount of catalyst added is 5% of the mass of fluorosilicic acid;

[0059] Reaction conditions: temperature 140℃, time 2 hours, stirring speed 300 rpm;

[0060] Product processing: Same as in Example 1;

[0061] Performance data: fluorine conversion rate 98.9%, no agglomeration during the reaction process, specific surface area of ​​composite product 46m² / g, hydrogen fluoride purity 99.7%, by-products can be used as high-value building material fillers.

[0062] Example 6: Catalyst regeneration and reuse (5 consecutive batches):

[0063] Fluorosilicic acid: by-product mother liquor from wet-process phosphoric acid (filtered through 5μm after clarification and sedimentation), mass concentration 20%;

[0064] Sulfuric acid: 96% by mass, filtered as in Example 1;

[0065] SiF6 2- With H + Molar ratio: 1:5;

[0066] Composite mineral catalyst: The catalyst after the reaction in Example 1 (after solid-liquid separation, calcination at 550°C for 3 hours, and regeneration by washing with dilute hydrochloric acid) was used. The mass ratio of γ-Al2O3 to diatomaceous earth was 1:3, and the amount added was 5% of the mass of fluorosilicic acid.

[0067] Reaction conditions: temperature 140℃, time 2 hours, stirring speed 300 rpm;

[0068] Product processing: Same as in Example 1;

[0069] Performance data: Fluorine conversion rate 97.5%, no clumping during the reaction process, specific surface area of ​​composite product 30m² / g, hydrogen fluoride purity 99.5%, by-products can be used as soil conditioners.

[0070] Comparative Example 1: No catalyst added:

[0071] Fluosilicic acid: pure product, mass concentration 20%;

[0072] Sulfuric acid: mass concentration 96%, filtration treatment same as example 1;

[0073] SiF6 2- With H + Molar ratio: 1:5;

[0074] Catalyst: none;

[0075] Reaction conditions: temperature 140℃, time 2 hours, stirring speed 300 rpm;

[0076] Product treatment: same as example 1;

[0077] Performance data: fluorine conversion rate 72%, obvious caking after 1 hour of reaction, product specific surface area <5 m² / g, hydrogen fluoride purity 98.0%, by-products do not meet GB18599-2020 Class I solid waste standards, need landfill disposal.

[0078] Comparative example 2: only add γ-Al2O3 (without diatomite):

[0079] Fluosilicic acid: pure product, mass concentration 20%;

[0080] Sulfuric acid: mass concentration 96%, filtration treatment same as example 1;

[0081] SiF6 2- With H + Molar ratio: 1:5;

[0082] Catalyst: only γ-Al2O3 (specific surface area 180 m² / g), added amount 5% of the mass of fluosilicic acid;

[0083] Reaction conditions: temperature 140℃, time 2 hours, stirring speed 300 rpm;

[0084] Product treatment: same as example 1;

[0085] Performance data: fluorine conversion rate 95%, hard deposition layer formed at the bottom of the reactor after the reaction, product specific surface area 8 m² / g, hydrogen fluoride purity 99.2%, by-products difficult to be recycled, need further treatment.

[0086] Comparative example 3: only add diatomite (without γ-Al2O3):

[0087] Fluosilicic acid: pure product, mass concentration 20%;

[0088] Sulfuric acid: mass concentration 96%, filtration treatment same as example 1;

[0089] SiF62- with H + Molar ratio: 1:5;

[0090] Catalyst: diatomite (calcined at 500°C for 2 hours, SiO2≥85%) only, added amount is 5% of the mass of fluosilicic acid

[0091] Reaction conditions: temperature 140°C, time 2 hours, stirring speed 300 rpm;

[0092] Product treatment: same as Example 1;

[0093] Performance data: fluorine conversion rate 79%, no caking during reaction, product specific surface area 15 m² / g, hydrogen fluoride purity 98.5%, low utilization rate of by-products, unable to meet the needs of high-end building materials or desulfurization.

[0094] Performance data comparison table:

[0095]

[0096] In the 6 examples, the composite catalyst composed of γ-Al2O3 and diatomite all achieved a fluorine conversion rate ≥97.5% and no caking, while Comparative Example 1 (without catalyst) had a conversion rate of only 72% and caking, Comparative Example 2 (γ-Al2O3 only) had a conversion rate of 95% but deposition, and Comparative Example 3 (diatomite only) had a conversion rate of 79%, proving that the acidic sites of γ-Al2O3 can accelerate the reaction (improve the conversion rate), and the porous structure of diatomite can guide the in-situ crystallization of calcium sulfate (prevent caking), and the two can solve the core problems of traditional processes.

[0097] Examples 2 (catalyst ratio 1:2), 3 (high concentration of raw materials), and 4 (low catalyst addition amount) all maintained high conversion rates and no caking; the composite product specific surface area of Example 5 (diatomite modification) reached 46 m² / g, which was 43.8% higher than that of unmodified Example 1, and the fluorine conversion rate increased to 98.9%, indicating that silane coupling agent modification can enhance the interfacial compatibility of diatomite and calcium sulfate, further optimizing the product structure.

[0098] Example 6 used regenerated catalyst (5 batches in a row), and the fluorine conversion rate still reached 97.5%, and the wet-process phosphoric acid by-product fluosilicic acid could be directly utilized, proving that the process does not require high-purity raw materials, the catalyst can be recycled at low cost, and has potential for industrial application.

[0099] The by-products of the embodiments can meet the I-class solid waste standard of GB18599-2020 and can be used as cement retarder and desulfurizer, while the by-products of the comparative examples need to be landfilled or treated; meanwhile, the reaction temperature of the embodiments is 120-160℃ (traditional process > 250℃), the energy consumption is reduced by about 40%, and the equipment can use 316L stainless steel (instead of hastelloy), which greatly reduces the investment cost.

[0100] The composite catalyst system and the mild process of the present application achieve the three goals of efficient production of hydrogen fluoride, resource utilization of by-products, and stable and low-consumption process, which are superior to the traditional non-catalytic or single catalyst process.

[0101] The above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for producing hydrogen fluoride from fluorosilicic acid, characterized in that, The method includes the following steps: A 15% to 30% aqueous solution of fluorosilicic acid is mixed with a 93% to 98% concentrated sulfuric acid solution containing SiF6 in fluorosilicic acid. 2- With sulfuric acid H + The molar ratio of the mixture is 1:4 to 1:6 to form a reaction precursor solution. The fluorosilicic acid is derived from the by-product fluorosilicic acid mother liquor produced during the wet process of phosphoric acid production. It is used after clarification, sedimentation and 5μm filtration. A composite mineral catalyst is added to the reaction precursor solution. The amount of the composite mineral catalyst added is 3% to 8% of the mass of fluorosilicic acid. The composite mineral catalyst is composed of γ-Al2O3 and natural diatomaceous earth in a mass ratio of 1:2 to 1:

4. The specific surface area of ​​γ-Al2O3 is not less than 180 m² / g, the pore volume is 0.4 to 0.6 cm³ / g, and the average pore size is 5 to 8 nm. The reaction mixture containing the composite mineral catalyst was reacted at 120°C to 160°C for 1.5 to 3 hours with a stirring speed of 200 to 400 rpm; the hydrogen fluoride gas generated by the reaction was condensed and dehydrated, and then collected through a two-stage cold trap to obtain anhydrous hydrogen fluoride product. The calcium sulfate generated during the reaction crystallizes in situ inside and on the surface of the porous framework of diatomite, forming a ternary composite solid product of Al2O3-diatomite-calcium sulfate with a specific surface area of ​​20 to 40 m² / g. The calcium sulfate exists in the form of hemihydrate gypsum or anhydrous gypsum.

2. The method for producing hydrogen fluoride from fluorosilicic acid according to claim 1, characterized in that, The composite mineral catalyst is prepared by the following method: γ-Al2O3 powder and diatomaceous earth powder are dry-mixed for 30 minutes, deionized water is added to make a slurry with a solid content of 40%, the slurry is stirred and aged at 60°C for 2 hours, spray-dried to form microspheres with a particle size of 100 to 300 μm, and then calcined in air at 550°C for 3 hours.

3. The method for producing hydrogen fluoride from fluorosilicic acid according to claim 2, characterized in that, The diatomaceous earth was surface modified with silane coupling agent KH-550 before being composited: the diatomaceous earth was dispersed in an ethanol-water mixed solvent, 2% of the mass of diatomaceous earth KH-550 was added, the mixture was reacted at 60°C for 4 hours, and then filtered and dried before use.

4. The method for producing hydrogen fluoride from fluorosilicic acid according to claim 1, characterized in that, The reaction temperature was 140℃, the reaction time was 2 hours, the concentration of fluorosilicic acid was 20%, the concentration of sulfuric acid was 96%, the amount of composite mineral catalyst added was 5% of the mass of fluorosilicic acid, and the mass ratio of γ-Al2O3 to diatomaceous earth was 1:

3.

5. The method for producing hydrogen fluoride from fluorosilicic acid according to claim 1, characterized in that, The concentrated sulfuric acid was filtered through a 0.2 μm polytetrafluoroethylene membrane.

6. The method for producing hydrogen fluoride from fluorosilicic acid according to claim 1, characterized in that, The two-stage cold traps are a -20°C ethylene glycol / water mixed cold trap and a -78°C dry ice / acetone cold trap, used for the graded removal of moisture, sulfuric acid mist and capture of hydrogen fluoride.

7. The method for producing hydrogen fluoride from fluorosilicic acid according to claim 1, characterized in that, The Al2O3-diatomite-calcium sulfate ternary composite solid product, after being washed and dried, is used as a cement retarder at a dosage of 0.5% to 2% of the cement mass.

8. The method for producing hydrogen fluoride from fluorosilicic acid according to claim 1, characterized in that, Diatomaceous earth is natural diatomaceous earth that has been calcined at 500℃ for 2 hours. Its SiO2 content is not less than 85%, its bulk density is 0.3 to 0.5 g / cm³, its porosity is greater than 70%, and its average pore size is 0.5 to 2 μm.

9. The method for producing hydrogen fluoride from fluorosilicic acid according to claim 1, characterized in that, The composite mineral catalyst is regenerated after solid-liquid separation, calcination at 550°C, and washing with dilute hydrochloric acid after the reaction is completed.

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