64 results about "Silicon tetrafluoride" patented technology

The invention belongs to the field of inorganic chemical industry, and particularly relates to a method and a system for efficiently utilizing a phosphate fertilizer byproduct, the method comprises the following steps: carrying out acidolysis on fluosilicic acid with the concentration of more than or equal to 45% wt and concentrated sulfuric acid to generate a mixed solution of silicon tetrafluoride gas and fluorosulfonic acid; the mass ratio of the fluosilicic acid to the concentrated sulfuric acid is controlled to be 1: (4-15); pyrolyzing the obtained fluorosulfonic acid to generate dilute sulphuric acid, hydrogen fluoride and water vapor, forming 98% concentrated sulphuric acid from part of dilute sulphuric acid and fuming sulphuric acid, drying hydrogen fluoride to obtain crude hydrogen fluoride gas, and condensing and rectifying to obtain anhydrous hydrogen fluoride; the rest dilute sulphuric acid is partially compounded and then returned for acidolysis, and the rest dilute sulphuric acid is used for producing white carbon black and flows back to a wet-process phosphoric acid system; and circularly absorbing the obtained silicon tetrafluoride gas by using secondary concentrated fluosilicic acid to obtain fluosilicic acid with the mass concentration of more than or equal to 45%, recycling the fluosilicic acid for acidolysis reaction, and modifying the concentrated by-product silicon dioxide to obtain the high-activity white carbon black. The problems of energy consumption and cost are solved, and efficient circulation and poly-generation of fluorine and silicon resources are achieved in the whole process.

The invention discloses a method for preparing hydrogen fluoride and co-producing fumed silica from low-concentration fluosilicic acid, which belongs to the technical field of inorganic chemical industry and comprises the following steps: concentrating low-concentration fluosilicic acid under reduced pressure; mixing concentrated sulfuric acid with system circulating sulfuric acid, reacting with concentrated fluosilicic acid, and performing gas-liquid separation to obtain mixed liquid of silicon tetrafluoride gas, hydrogen fluoride and sulfuric acid; and washing the separated silicon tetrafluoride gas and / or silicon tetrafluoride gas generated by a wet-process phosphoric acid process with concentrated sulfuric acid, reacting with water vapor, hydrogen and oxygen, and dedusting to obtain the fumed silica. The method has the advantages of simple process flow, low production cost, high product quality, low three-waste output and the like. Besides, low-grade and low-concentration fluosilicic acid is used as a raw material, fluorine and silicon elements are efficiently separated, high-value fumed silica and high-quality hydrogen fluoride are prepared, and good social and economic values are embodied; and cyclic utilization of byproducts such as sulfuric acid reduces environmental pollution and three-waste treatment pressure, and has good environmental protection benefits.

The invention discloses a system and method for preparing high-purity silicon dioxide, and the system comprises a Venturi injection pump which is used for mixing silicon tetrafluoride gas with water to form jet flow; the swirler is connected with the venturi injection pump, and the swirler is connected with the venturi injection pump; the jet flow enters the swirler and then is subjected to separation treatment, and underflow and upper-layer overflow are formed; and the separation device is connected with the cyclone and is used for separating the silicon dioxide from the underflow and the upper overflow to obtain silicon dioxide particles. The method for preparing the high-purity silicon dioxide has the advantages of being simple in process, high in product purity, environmentally friendly, low in production cost, convenient for industrial production and the like, and has high economic benefits and social benefits.

The invention belongs to the technical field of aluminum smelting solid hazardous waste recycling, and particularly relates to a recycling method of aluminum oxide-rich complex electrolyte hazardous waste. According to the method, the complex aluminum electrolyte hazardous waste, aluminum salt and silicon-containing oxide are mixed and then subjected to segmented roasting-leaching treatment, fluorine in the electrolyte is converted into aluminum fluoride firstly and then converted into silicon tetrafluoride gas, separation of fluorine and aluminum and separation of gas and solid are achieved, and sodium and lithium elements are converted into soluble salt and further separated and recycled. According to the process, collaborative recovery and high-value utilization of various valuable elements in the complex aluminum electrolyte hazardous waste are achieved. The whole technological process is environment-friendly, toxic and harmful gas emission is avoided, secondary solid waste residues are not generated, the method has the advantages of being simple in process, high in recovery rate, high in product additional value and the like, and a feasible technical scheme is provided for resource utilization of the aluminum electrolysis solid waste.

The application discloses a method and system for preparing ammonium bifluoride from hydrofluoric acid waste liquid, which comprises the following steps: (1) adding the hydrofluoric acid waste liquid into an electrolytic cell, transporting the electrolytic cell to a first reaction kettle after electrodepositing treatment, adding silicon dioxide, then stirring and reacting, and returning the generated silicon tetrafluoride and hydrofluoric acid into a spray tower to react and then return to the first reaction kettle, and then adding ammonia water to perform neutralization reaction; (2) filtering the solid-liquid mixture I, evaporating and drying the obtained filtrate I to obtain an ammonium nitrate product, and returning the obtained filter cake I to a second reaction kettle, adding ammonia water to adjust the pH value, and then stirring and reacting; (3) filtering the solid-liquid mixture II, returning the obtained filter cake II to the first reaction kettle for reuse, transporting the obtained filtrate II to a reactor, adding hydrofluoric acid to perform reaction, and then performing evaporation and drying treatment to obtain an ammonium bifluoride product. The method is simple in process, low in energy consumption, convenient to operate and convenient for industrialized production and application.

The application provides a method for removing parasitic silicon carbide, which comprises using silane and an oxygen-free cleaning gas containing hydrogen and hydrogen fluoride gas, keeping the cleaning temperature in a cleaning chamber not lower than 1300 DEG C, and removing the parasitic silicon carbide under a cleaning pressure not lower than 100 mbar, so as to improve the cleaning rate. The hydrogen gas plays a dilution role on the hydrogen fluoride gas, and meanwhile, the cleaning efficiency is considered, so as to prevent over-etching. The silicon species generated by the decomposition of silane can generate gaseous silicon tetrafluoride with fluorine, and is adsorbed on the surface of exposed graphite basal body after cleaning, so as to reduce the significant damage of the hydrogen fluoride gas to the surface of exposed graphite basal body after cleaning. In the later cleaning stage, the silane is switched to propane, so as to improve the silicon-rich atmosphere formed in the cleaning chamber due to the introduction of silane, reduce or avoid the problem that the silicon species adsorbed on the surface of the graphite basal body is difficult to be taken away by the flow field of the purge gas, and make the surface of the epitaxial wafer appear obvious cluster phenomenon.

This invention relates to a silicon tetrafluoride gas absorption device for the production of hydrofluoric acid from fluorosilicic acid. The device includes a housing, within which is an absorption cylinder extending horizontally along its axis. One end of the absorption cylinder is fixedly connected to an inlet pipe, and the other end is rotatably mounted to a liquid inlet pipe via a bearing. The housing is equipped with a drive motor for rotating the inlet pipe and an inlet structure for introducing silicon tetrafluoride gas into the inlet pipe. The end of the liquid inlet pipe away from the absorption cylinder extends out of the housing and is sealed and fixedly connected to it. A suction pipe is located inside the liquid inlet pipe, with its inner end extending to the lower side of the absorption cylinder. The outer wall of the absorption cylinder has several filter holes, each hinged with a sealing cap. A torsion spring on the hinge shaft of the sealing cap keeps it sealed to the filter holes. The housing also includes a gas supply pipe and a gas extraction pipe. Compared to existing technologies, this invention offers better absorption of silicon tetrafluoride and better separation of silica hydrates.

The invention discloses a preparation method of high-purity silane suitable for a small experimental device, which comprises the following steps: sequentially connecting and arranging a main reactor, a second reactor, a condenser, a silane buffer tank, a booster pump and a silane steel cylinder, and injecting hydrogen, nitrogen and silicon tetrafluoride materials into the main reactor after passing through the same mass flow controller; then the material enters a second reactor through a gas phase outlet pipeline at the top of the main reactor, a gas phase outlet at the top of the second reactor is connected with an inlet at the bottom of a condenser, an outlet of the condenser is connected with a silane buffer tank, and an outlet pipeline is arranged at the top of the silane buffer tank; materials enter the booster pump through the outlet pipeline, are pressurized in the booster pump and then are fed into the silane steel cylinder to be stored, so that the complexity of the reaction device is simplified, the energy consumption is reduced, and the problems of huge device size, complex process conditions and the like are solved.

The application discloses a method for preparing white carbon black and ammonium fluoride from silicon tetrafluoride, wherein the silicon tetrafluoride gas enters an ammoniation reactor through the middle part, the carrier gas and the ammonia gas enter the ammoniation reactor through the bottom part, solid particles SiO2 and NH4F are generated, the carrier gas flows out from the top outlet of the ammoniation reactor and enters a separator, solid slurry is rapidly formed after being washed in the spray at the top inlet of the separator, and then the solid slurry is settled into the separator; inert solvents are added into the separator, and SiO2 and NH4F are separated by using the density difference. The application uses the SiF4 gas obtained by decomposing fluorosilicic acid or the by-product silicon tetrafluoride gas of phosphate fertilizer as raw materials to continuously produce high-quality white carbon black and ammonium fluoride, and the method is continuous, stable, simple, and has a long operation period, and effectively overcomes the defects of the existing intermittent process technology.

The invention provides a method for removing silicon tetrafluoride in boron trifluoride by adopting a chemical method, and belongs to the technical field of purification and impurity removal. The preparation method comprises the following steps: introducing a boron trifluoride raw material into anisole for complex reaction to obtain complex product feed liquid; the molar ratio of the anisole to the boron trifluoride raw material is 1: (0.3-0.8); performing exhaust treatment on the complexing product feed liquid to obtain exhaust feed liquid; the temperature of the exhaust treatment is 30-40 DEG C; the exhaust feed liquid is subjected to cracking treatment, and purified boron trifluoride is obtained; the final temperature of the cracking treatment is 100-120 DEG C. The method disclosed by the invention is excellent in desilicication effect, can meet the requirement of electronic grade boron trifluoride on the content of silicon tetrafluoride, is high in product yield and low in energy consumption, and greatly reduces the cost.

This invention relates to a chemical equipment, specifically a silicon tetrafluoride concentrator. The technical solution includes a main gas inlet pipe, characterized in that at least one set of spray cylinder sections are connected in series within the main gas inlet pipe. Each spray cylinder section includes vertical and horizontal sections. The vertical section has gas inlets and outlets at different heights. The gas inlet of the vertical section is connected to the main gas inlet pipe, and the gas outlet of the vertical section is connected to the inlet of the horizontal section. The top of the horizontal section has multiple spray mounting ports, into which spray pipes are inserted. The lower end of each spray pipe is connected to a nozzle, and the upper end is connected to a main liquid pipeline. This invention features simple structure, low equipment height, low investment and operating costs, sufficient gas-liquid contact, good concentration effect, corrosion and wear resistance, convenient maintenance, and stable and reliable operation.

The invention relates to the technical field of electronic special gas purification, in particular to a separation device and method for removing carbon dioxide and hydrogen sulfide in silicon tetrafluoride mixed gas through a two-stage membrane. The two-stage membrane of the separation membrane element of the CHA molecular membrane and the polyimide membrane is adopted, and the rectifying tower is coupled, so that the use of chemical substances such as sulfuric acid and an adsorbent can be avoided on the basis of obtaining the high-purity silicon tetrafluoride product gas, and the production cost and the post-treatment cost are reduced.

This invention discloses a method for efficiently preparing aluminum fluoride from aluminum ash, comprising the following steps: Aluminum ash is ground, preheated, and then oxidized for denitrification. Silicon chloride is used to chlorinate the aluminum, iron, and magnesium in the oxidized aluminum ash into aluminum chloride, ferric chloride, and magnesium chloride. High-purity aluminum chloride is obtained through multi-stage condensation and purification. The aluminum chloride is then gasified, preheated, and reacted with silicon tetrafluoride to produce aluminum fluoride and silicon chloride. The silicon chloride is recycled for use in the chlorination process. This invention significantly improves the oxidative denitrification efficiency of aluminum ash through grinding and activation. The chlorination process uses silicon chloride as the chlorinating agent, eliminating the need for carbon addition. The chlorination products are easily separated, and the operation is simple. Silicon tetrafluoride is used to fluorinate aluminum chloride to prepare aluminum fluoride. The byproduct silicon chloride can be recycled within the system, effectively reducing production costs. Simultaneously, the system has high energy utilization, enabling the harmless treatment of aluminum ash and the large-scale, efficient preparation of aluminum fluoride, resulting in significant economic and social benefits.

The invention discloses a method for preparing a silicon isotope and a boron isotope. The method comprises the following steps: purifying boron powder through a pretreatment process to obtain high-purity boron powder; vacuumizing the reactor to-0.08 MPa to-0.09 MPa, then introducing inert gas to replace air in the reactor, and carrying out reduction reaction on the high-purity boron powder and the high-purity silicon tetrafluoride gas rich in silicon-28 in the reactor to obtain a crude silicon-28 isotope product; the method comprises the following steps: removing impurities from a crude silicon-28 isotope product through plasma zone melting to obtain a silicon-28 isotope product, removing excessive silicon tetrafluoride from generated boron trifluoride gas through a low-temperature rectification process, preparing boron-10 and boron-11 isotopes, and returning the excessive silicon tetrafluoride to a system for recycling. The one-step coupling preparation technology of the silicon and boron isotopes is developed, the silicon-28 isotopic, the boron-10 isotope and the boron-11 isotope are prepared at the same time, efficient directional conversion of the silicon and boron isotopes is achieved, the production cost is further reduced, and the economic benefits of the process are remarkable.

The invention discloses a process and a device for preparing hydrogen fluoride by a fluosilicic acid complexing method. The process comprises the following steps: mixing a fluosilicic acid solution, a complexing solution and a cross-linking agent to generate a complexing reaction to obtain a first mixed material containing a metastable state complex; raising the temperature of the first mixed material to be stable, so as to obtain a second mixed material containing a solid-phase steady-state complex; and carrying out solid-liquid separation on the second mixed material, drying the solid, and carrying out thermal decomposition to obtain hydrogen fluoride gas, silicon tetrafluoride gas and a liquid material. The device comprises complex reaction equipment, cross-linking reaction equipment, first solid-liquid separation equipment, a drying machine and complex decomposition equipment. The complexing agent can be recycled for a long period and has the advantages of being high in separation efficiency, small in fluosilicic acid loss, high in hydrogen fluoride yield, low in material consumption and energy consumption and the like, and on the basis that a hydrogen fluoride product reaches superior product indexes, the fluosilicic acid complexing rate reaches 98% or above, the complex decomposition rate reaches 95% or above, and the total hydrogen fluoride yield reaches 90% or above.

The application discloses a closed loop process for synchronously increasing the value of silicon and fluorine components in silicon tetrafluoride, and belongs to the technical field of fluorine-containing silicon byproduct resource utilization. The steps are as follows: 1) mixing anhydrous alcohol with triethylamine, and introducing silicon tetrafluoride gas at 0-30 DEG C to generate alkyl orthosilicate and triethylamine monohydrofluoride; 2) distilling the reaction liquid to recover alcohol, performing vacuum rectification to obtain alkyl orthosilicate product, and separating to obtain triethylamine monohydrofluoride; 3) adding triethylamine monohydrofluoride into water, and performing heating reflux reaction with inorganic alkali or basic oxide to separate to obtain triethylamine crude product and fluorinated metal salt; 4) after dehydration rectification, the triethylamine crude product is recycled to step 1) with recovered alcohol; and the fluorinated metal salt is post-treated to obtain high-purity fluorinated metal salt. The process has low reaction temperature, high alkyl orthosilicate yield, recyclable triethylamine, all fluorine solidified into high-value-added products, no three-waste emissions, and can be continuously industrialized.

The invention relates to the technical field of preparation of inorganic fluorine-containing special gas, and discloses a preparation method for preparing anhydrous hydrogen fluoride and silicon tetrafluoride based on low-temperature decomposition of fluosilicic acid organic alkali dihydrate, which comprises the following steps: S1, mixing dilute fluosilicic acid and organic alkali for reaction: slowly dropwise adding the organic alkali into hot fluosilicic acid, and after dropwise adding is completed, performing reaction for 2-4 hours; continuously heating and stirring until complete dissolution, reducing the stirring rotating speed in a gradient manner, naturally and slowly cooling and crystallizing, and performing suction filtration and purification to obtain a fluosilicic acid organic alkali dihydrate intermediate; s2, distilling and pyrolyzing the fluosilicic acid organic alkali dihydrate intermediate at the distillation temperature of more than or equal to 140 DEG C, and decomposing to obtain hydrogen fluoride and silicon tetrafluoride; according to the method, the enrichment efficiency of the dilute fluosilicic acid can be effectively improved, the fluosilicic acid organic alkali complex containing crystal water can be decomposed with low energy consumption, and the yield of the obtained product can meet the requirement of industrial production. The method is simple to operate, short in preparation route, stable in reaction process, low in reaction temperature and suitable for industrial production.

The invention belongs to the technical field of resource recovery and material preparation, and provides a method for preparing silicon powder by using an out-of-service wind turbine blade. By adopting the method disclosed by the invention, the silicon powder with higher purity and the resin with lower ash content can be recovered from the retired wind turbine blade. The method comprises the following steps that S1, the retired wind power blade is disassembled, and non-glass fiber composite material parts are removed; then crushing into fragments; s2, grinding the fragments; s3, carrying out first-stage reaction on the powder material in a mixed solution of hydrofluoric acid and an organic solution; then carrying out second-stage reaction to generate silicon tetrafluoride gas, and filtering feed liquid after the reaction to obtain solid-phase resin; collecting silicon tetrafluoride gas, introducing the silicon tetrafluoride gas into a weakly alkaline aqueous solution, stirring, and standing to obtain silicic acid precipitate; s4, filtering, washing and calcining the silicic acid precipitate to obtain a silicon powder crude product; and S5, purifying and drying the silicon powder crude product to obtain a silicon powder product.

The present application provides a cleaning method for silicon carbide growth equipment, which comprises the following steps: introducing an oxygen-free cleaning gas containing hydrogen and hydrogen fluoride into a growth chamber, and then introducing monosilane. After performing the step of alternately introducing the oxygen-free cleaning gas and monosilane at least once, the step of growing a silicon carbide layer is performed. The predetermined temperature in the growth chamber is not less than 1400 degrees Celsius, and the preset pressure higher than the growth pressure is controlled, which is conducive to improving the cleaning rate. Hydrogen plays a dilution role on the strong oxidizing hydrogen fluoride, while the cleaning efficiency is taken into account to prevent over-etching. The silicon species generated by the decomposition of monosilane can generate gaseous silicon tetrafluoride with fluorine and be adsorbed on the corrosion-resistant carbon-based surface, reducing the significant damage of hydrogen fluoride to the exposed corrosion-resistant carbon-based surface after cleaning. Finally, the step of growing a silicon carbide layer can fix the particles adsorbed on the exposed surface in the growth space which are not easy to be removed by blowing, and also provides a good growth environment for subsequent growth.

The invention discloses a process and system for producing electronic-grade silane through thermal coupling reactive distillation, and relates to the technical field of electronic-grade silane generation, and the system mainly comprises a reactive distillation tower, a compression system, a silane crude distillation tower, a silane refining tower, a silane adsorption tower, a solvent recovery tower, a tail gas treatment system and a filtering and drying system. According to the technology, silicon tetrafluoride gas and a sodium aluminum hydride solution are introduced into a reactive distillation tower for a reverse contact reaction, generated crude silane gas is subjected to compression, multi-stage distillation and adsorption purification, and finally 9N-12N electronic-grade silane is obtained. A stirring kettle is replaced by reactive distillation, so that the risk of dynamic seal leakage is thoroughly eliminated; by adopting a multi-stage thermal coupling technology, reaction heat, tower bottoms and compression heat are used for heating the system, so that the energy consumption is obviously reduced; the method realizes cyclic utilization of the solvent and fluorine resources, and has the advantages of high safety, high product purity, low energy consumption and comprehensive utilization of resources.

The present application belongs to the technical field of fluorine-containing silicon slag recycling, and specifically discloses a method for preparing white carbon black from fluorine-containing silicon slag. The fluorine-containing silicon slag is first dried and calcined at high temperature to make fluorine escape in the form of silicon tetrafluoride; the tail gas is absorbed by multi-stage water circulation to obtain an acidic solution. The calcined residue is reacted with calcium hydroxide to generate calcium silicate, which is then acid-dissolved by sulfuric acid and separated from calcium sulfate by water washing. The silicon dioxide is dried and dehydrated by n-butanol to obtain white carbon black. The present application can efficiently treat the fluorine-containing silicon slag generated in the production of anhydrous hydrogen fluoride by fluorosilicic acid method, realize the recycling of fluorine and silicon components, convert fluorine into an acidic solution, and convert silicon into high-value-added white carbon black, thus achieving both environmental and economic benefits.

The utility model discloses a process device for concentrating and absorbing silicon tetrafluoride gas, which relates to the field of gas absorption and comprises an absorption box and a box door, an absorption cavity and two symmetrical slots are arranged at the front end of the absorption box, the slots are arranged on two sides of the absorption cavity, and the absorption cavity is communicated with the slots. A filter screen inserting assembly, a water circulation assembly and an air inlet assembly are arranged on the absorption box, the filter screen inserting assembly comprises a filter screen body, inserting blocks are fixedly connected to the two sides of the filter screen body, the outer ends of the inserting blocks are slidably connected with inserting grooves, clamping holes are formed in the upper ends of the inserting grooves, inserting columns are slidably connected to the inner walls of the clamping holes, and the outer ends of the inserting columns are slidably connected with the absorption box; the upper end of the inserting column is fixedly connected with a moving column and a spring, the moving column is sleeved with the spring, the upper end of the spring is fixedly connected with an L-shaped plate, and the moving column penetrates through the L-shaped plate. According to the utility model, the filter screen body for filtering molded silica gel for a long time can be conveniently replaced, and the filtering effect of the filter screen body is always ensured.

The application provides a method for preparing silicon tetrafluoride by using fluorine-containing silicon slag, and belongs to the field of fluorine-containing silicon slag utilization; the method comprises the following steps: washing the fluorine-containing silicon slag with brine A, filtering to obtain silicon dioxide and filtrate; adding brine B to the obtained filtrate, filtering to obtain a silicon tetrafluoride precursor and secondary filtrate; and drying, calcining the obtained silicon tetrafluoride precursor to obtain silicon tetrafluoride. Compared with the prior art, the fluorine-containing silicon slag is washed with specific ammonium brine, so that the fluosilicic acid in the fluorine-containing silicon slag can be efficiently extracted, the yield of the silicon tetrafluoride precursor is improved, the method is more energy-saving, the raw material cost is lower, the process control is simpler, and the silicon tetrafluoride precursor is not prone to sticking to the wall during the calcining process.

The invention discloses phosphoric acid defluorination equipment based on silicon dioxide. The phosphoric acid defluorination equipment is used for improving the recovery rate of fluorine resources. The device comprises a clarifying tank, a mixing device and a concentrating device, the clarifying tank is connected with the mixing device through a pipeline and is used for conveying clarified dilute phosphoric acid to the mixing device; an anhydrous hydrogen fluoride device and a mixing tank are arranged in the mixing device, the anhydrous hydrogen fluoride device is used for producing silicon dioxide, the anhydrous hydrogen fluoride device is connected with the mixing tank through a pipeline and used for mixing the dilute phosphoric acid and the silicon dioxide, the mixing tank is connected with the concentration device through the pipeline, and the concentration device is used for concentrating the dilute phosphoric acid and the silicon dioxide. The conveying device is used for conveying a fluoride-containing mixed solution generated after mixing to the concentration device; the concentration device is used for heating and concentrating the fluoride-containing mixed solution, and in the concentration process, fluoride in the fluoride-containing mixed solution is heated and decomposed to generate silicon tetrafluoride gas so as to realize phosphoric acid defluorination.

The invention discloses a silicon tetrafluoride resource utilization method, and relates to the field of silicon tetrafluoride resource utilization. The method comprises the following steps: S1, introducing silicon tetrafluoride into an ammonium bifluoride solution, and filtering to obtain ammonium fluosilicate precipitate and first filtrate; s2, adding a desilicication precipitator into the first filtrate, and filtering to obtain fluosilicate precipitate and second filtrate; s3, mixing the second filtrate with concentrated sulfuric acid, heating, evaporating and analyzing, absorbing the obtained gas with water to obtain hydrofluoric acid, and crystallizing and separating out the residual liquid to obtain ammonium salt. The whole process route is mild in reaction condition and high in safety coefficient; high temperature and external electric field are not needed, and energy consumption is low; no secondary waste is generated, and the comprehensive utilization degree of resources is high.

The invention provides a method for separating HCl in SiF4 gas, which comprises the following steps: S1, introducing silicon tetrafluoride gas containing hydrogen chloride into glycerol to carry out gas absorption to obtain a mixture containing hydrogen chloride, silicon tetrafluoride and glycerol and absorbed silicon tetrafluoride gas; and S2, desorbing hydrogen chloride and silicon tetrafluoride in the mixture, performing at least two stages of desorption under a negative pressure condition, and increasing the desorption temperature stage by stage. According to the method disclosed by the invention, glycerol is used as an absorbent, and high-selectivity absorption of HCl in SiF4 can be realized.

The application belongs to the technical field of resource recycling and material preparation, and provides a method for preparing silicon powder by using retired wind power blades. The method can recycle silicon powder with high purity and resin with low ash content from the retired wind power blades. The method comprises the following steps: S1, disassembling the retired wind power blades, removing the non-glass fiber composite material parts, and then crushing into fragments; S2, grinding the fragments; S3, carrying out the first stage reaction of the powder material in a mixed solution of hydrofluoric acid and an organic solution; then carrying out the second stage reaction to generate silicon tetrafluoride gas, filtering the material liquid after the reaction to obtain solid-phase resin; collecting the silicon tetrafluoride gas, stirring and standing in a weak alkaline aqueous solution to obtain a silicon acid precipitate; S4, filtering, washing and calcining the silicon acid precipitate to obtain a silicon powder crude product; and S5, purifying and drying the silicon powder crude product to obtain a silicon powder product.

The invention relates to a method for preparing hydrogen fluoride by a sulfuric acid method, which comprises the following steps: S1, mixing concentrated fluosilicic acid and first concentrated sulfuric acid, heating to obtain fluorine-containing sulfuric acid and silicon tetrafluoride gas, and distilling the fluorine-containing sulfuric acid to obtain hydrogen fluoride; s2, contacting the silicon tetrafluoride gas obtained in S1 with second concentrated sulfuric acid to obtain primarily purified silicon tetrafluoride; s3, contacting the primarily purified silicon tetrafluoride obtained in S2 with an organic solution dissolved with fluosilicate to obtain secondarily purified silicon tetrafluoride; and S4, dissolving the secondarily purified silicon tetrafluoride obtained in the step S3 into dilute fluosilicic acid to prepare concentrated fluosilicic acid, and recycling the concentrated fluosilicic acid in the step S1. The method solves the technical problems that 0.1-2wt% of hydrogen chloride impurities are often contained in dilute fluosilicic acid in the prior art, are easy to accumulate in a system when hydrogen fluoride is prepared by a sulfuric acid method and are difficult to remove.

A method for producing a halogenated alkene, the method comprising converting a halogenated alkane represented by formula (1) into a halogenated alkene represented by formula (2) and a compound represented by formula (3) in a gas phase in the presence of silicon oxide and an alkali metal element. R1-R3 each independently represent a hydrogen atom, a fluorine atom, a methyl group, a fluorinated methyl group, an ethyl group, or a fluorinated ethyl group, and the number of carbon atoms in each of formulae (1)-(3) is 2-4.

This invention discloses a method for preparing aluminum fluoride from aluminum ash, comprising the following steps: First, chlorination and denitrification of finely ground and preheated aluminum ash is performed using chlorine gas, converting aluminum and aluminum nitride in the ash into aluminum chloride and nitrogen. Second, a secondary chlorination of aluminum, iron, and magnesium in the primary chlorination product is performed using silicon chloride, converting them into aluminum chloride, ferric chloride, and magnesium chloride. High-purity aluminum chloride is obtained through multi-stage condensation and separation. The aluminum chloride obtained from the two chlorinations is then gasified, preheated, and reacted with silicon tetrafluoride to produce aluminum fluoride and silicon chloride. The silicon chloride is recycled for secondary chlorination. This invention uses chlorine and silicon chloride sequentially to chlorinate aluminum ash twice, eliminating the need for carbon addition. The chlorination products are easily separated, and the operation is simple. The use of silicon tetrafluoride to fluorinate aluminum chloride to prepare aluminum fluoride, along with the recycling of the byproduct silicon chloride within the system, effectively reduces production costs. Simultaneously, the system has high energy utilization, enabling the harmless treatment of aluminum ash and the large-scale clean preparation of aluminum fluoride, resulting in significant economic and social benefits.