57results about "Silicon halogen compounds" patented technology

This invention discloses a process for purifying and concentrating dilute fluorosilicic acid solution using chemical extraction. The main steps are as follows: 1. Extraction: Dilute fluorosilicic acid and extractant are mixed in a certain ratio for chemical extraction. After extraction, the aqueous phase and the organic phase are separated. 2. Back-extraction: The organic phase and back-extraction solution are mixed in a certain ratio. Under certain operating conditions, fluorosilicic acid is back-extracted from the organic phase to obtain a concentrated fluorosilicic acid solution and raffinate. 3. Raffinate treatment: A saturated solution of soluble heavy metal salt is added to the raffinate in a certain ratio, and a chemical reaction is carried out under certain operating conditions. After the reaction is completed, centrifugation is performed to obtain heavy metal sulfate, which is recovered as a byproduct. The organic phase is then subjected to vacuum distillation to separate the extraction aid. The remaining organic matter is further decomposed by vacuum heating to obtain an organic extractant and inorganic acid vapor. The organic extractant is reused, and the inorganic acid vapor is condensed and recovered. This invention has good purification effect, simple process, and the extractant can be recycled.

The invention belongs to the technical field of industrial wastewater treatment and resource recovery, and particularly relates to an enhanced treatment method for recovering fluorine resources in semiconductor processing fluorine-containing wastewater. And step-by-step efficient recovery of sodium fluosilicate and calcium fluoride is realized through cooperation of precipitant compounding and pH regulation. The method comprises the following steps: firstly, adding a NaCl-NaHCO3 composite precipitator and sodium fluosilicate seed crystals to induce crystallization and recover hexagonal prism-shaped sodium fluosilicate single crystals; and after filtering, adding a CaCl2-Ca (OH) 2 composite precipitator and calcium fluoride seed crystals into the filtrate to generate large-particle calcium fluoride. And the impurity content in the recovered product respectively reaches the industrial sodium fluosilicate superior product standard and the metallurgical grade calcium fluoride secondary product standard. And the treated wastewater is neutral or weakly alkaline, so that the subsequent mixed treatment with other wastewater is facilitated.

The invention provides a lithium ion halide solid electrolyte, the chemical composition of the lithium ion halide solid electrolyte is LixMa + Nb + yClx + a + by, a is the valence of an element M, and b is the valence of an element N; 1 < = x < = 4, 0lt; y < = 1, 2 < = a < 5, and 2 < = b < = 5. The lithium ion halide solid electrolyte provided by the invention not only has high room-temperature ionic conductivity, but also has relatively good negative electrode contact stability due to relatively low valence. The invention also provides a preparation method of the lithium ion halide solid electrolyte, the raw materials adopted by the method are low in cost, and the synthesis technical route is simple.

Silicon subhalide-containing composite particles along with processes for producing and uses for the same. Where the silicon subhalide-containing composite particles have a Si content >30% by weight. Wherein the silicon is placed in and on the pores of a porous matrix. The silicon subhalide-containing composite particles include a halogen concentration of 0.0003 to 16% by weight, a pH of 3 to 9, a volume-weighted particle size distribution having diameter percentiles d50 of 0.5 to 20 μm, and a specific BET surface area of at most 170 m2 / g.

The application provides a quartz sand acid washing waste liquid resource treatment method, and belongs to the field of industrial waste water treatment, and comprises the following steps: adding magnetic composite seeds to the quartz sand acid washing waste liquid, and performing magnetic separation after stirring treatment; adding soluble potassium salt to the treated waste liquid to recover potassium fluosilicate; treating the filtrate through diffusion dialysis to obtain recovered acid and dialysis residual liquid; the diffusion dialysis treatment adopts an asymmetric membrane, the asymmetric membrane has a physical gradient of one side being a dense structure and the other side being a loose structure, and the dense structure side is in contact with the waste liquid; and adding calcium oxide or calcium hydroxide to the dialysis residual liquid for deep treatment and calcium recovery. The application provides a quartz sand acid washing waste liquid resource treatment method which is low in treatment cost, high in resource recovery rate and friendly to the environment, and realizes the differentiated resource recovery of the quartz sand acid washing waste liquid.

The invention discloses a wet-process phosphoric acid defluorination residue recycling coupling device and a production method, the coupling device is arranged in a wet-process phosphoric acid production system, and the coupling device comprises a spiral mixing reactor (1), a mixing reactor (2) and a fluorine-containing gas washing and recycling device (3) which are sequentially arranged and connected; the production method comprises the following steps: adding concentrated sulfuric acid with the temperature of 80-90 DEG C into the wet-process phosphoric acid defluorination residues and silica fume in a spiral mixing reactor according to the mass ratio of 100: (5-10), reacting for 40-60 minutes, controlling the reaction temperature to be 90-100 DEG C, returning slurry B to a wet-process phosphoric acid production pre-extraction system, and separating and purifying the slurry B to obtain the wet-process phosphoric acid defluorination residues. Fluorine-containing gases SiF and HF generated by the mixing reaction are sent to a fluorine-containing gas washing and recycling device through a waste gas main pipe to be washed to obtain a 8-15% fluosilicic acid solution. The coupling device is coupled with an existing wet-process phosphoric acid production system, a large number of newly-added equipment and procedures are reduced, the whole process is free of three-waste emission, the method is simple in process, the fluorine recovery rate is larger than or equal to 83%, meanwhile, phosphorus is efficiently recovered, and pollution of fluorine resources to the environment is reduced.

The invention relates to the technical field of magnesium fluosilicate production, in particular to a preparation method of magnesium fluosilicate for a concrete hardener, which comprises the following steps: adding a magnesium-containing compound into a fluosilicic acid solution to obtain a mixed solution; when it is judged that the preparation of the mixed solution does not meet the preset standard according to the turbidity gradient of the mixed solution, the preset adding rate is reduced; adding an impurity removal agent into the mixed solution meeting the preset standard, stirring, standing, precipitating and filtering to obtain magnesium fluosilicate filtrate; concentrating the magnesium fluosilicate filtrate until crystals are separated out to obtain magnesium fluosilicate crystal slurry; judging whether the preparation of the magnesium fluosilicate crystal slurry meets a preset standard or not according to the gray value variance; and carrying out centrifugal separation on the magnesium fluosilicate crystal slurry meeting the preset standard to obtain wet magnesium fluosilicate crystals, and drying the wet magnesium fluosilicate crystals to obtain a magnesium fluosilicate product. The preparation efficiency of the magnesium fluosilicate is improved.

The invention discloses a homogeneous reactor and application thereof, and belongs to the technical field of reactors. Comprising a stirring tank and a stirrer, wherein the stirrer comprises a stirring shaft coaxially arranged in the stirring tank, a motor for driving the stirring shaft and stirring blades on the stirring shaft; the lower part of the stirring tank is provided with a feed port, the top of the stirring tank is provided with an exhaust port, the lower part is a straight cylinder section, and the upper part is an expansion part; a lower guide cylinder is coaxially arranged at the lower part in the straight cylinder section, an upper guide cylinder is coaxially arranged at the upper part in the straight cylinder section, a plurality of spoilers are uniformly distributed on the inner wall of the top of the straight cylinder section, and a discharge hole is formed in the side wall of the top of the straight cylinder section; an upper plug flow blade, a lower plug flow blade and a floating foam scattering blade are sequentially arranged on the stirring shaft from bottom to top; the upper flow pushing blade is positioned at the lower part in the lower guide cylinder and is used for pushing liquid upwards; the lower flow pushing blade is positioned at the upper part in the upper guide cylinder and is used for pushing liquid downwards; the floating foam scattering blade is located in the expansion part, located above the liquid level in the stirring tank and used for scattering floating foam on the liquid level.

The application discloses a device for preparing potassium fluosilicate by using mixed acid and belongs to the technical field of potassium fluosilicate preparation, which comprises a fixing frame, the inner side of the fixing frame is provided with a reaction kettle shell, and the inside of the reaction kettle shell is provided with a stirring device; the top of the stirring device is fixedly connected with a gear one, the top sides of the reaction kettle shell are movably connected with a rotating shaft one, the top of the rotating shaft one is fixedly connected with a gear two, the bottom of the rotating shaft one is fixedly connected with a reciprocating screw rod, the outer side of the reciprocating screw rod is movably connected with a sliding plate, the inner side of the reaction kettle shell is fixedly connected with a sliding rod, the outer side of the sliding rod is movably connected with a sliding plate, the outer side surface of the sliding plate is provided with a groove, the inside of the groove is movably connected with a rotating shaft two, the outer side of the rotating shaft two is fixedly connected with a disturbance plate, and the bottom of the disturbance plate is fixedly connected with a flow guide fin. The application is used to solve the problem that the silicon powder is mixed with the mixed acid solution slowly in the early stage of reaction, thereby reducing the overall production efficiency.

The invention relates to the technical field of chemical product preparation, in particular to pure sandy sodium fluosilicate as well as a preparation method and application thereof. The preparation method of the pure sandy sodium fluosilicate comprises the following steps: S1, adding industrial sodium sulfate into hot water, dissolving, filtering to obtain a sodium sulfate solution, slowly adding the sodium sulfate solution into a fluosilicic acid solution according to a molar ratio of the fluosilicic acid solution to the sodium sulfate solution of 1: 1, stirring, centrifuging, and filtering to obtain a sodium fluosilicate filter cake; s2, dissolving the sodium fluosilicate filter cake in pure water according to a ratio of 1: 30 to obtain a colorless and transparent sodium fluosilicate saturated solution; s3, mixing the crushed ice blocks frozen by the pure water with cold pure water at 0-5 DEG C to obtain an ice-water mixture; preparing a sandy sodium fluosilicate seed crystal; s4, adding an ice-water mixture into the sodium fluosilicate saturated solution; meanwhile, adding sandy sodium fluosilicate seed crystals; s5, sodium fluosilicate crystals are separated out, the sodium fluosilicate crystals are centrifuged and dried, and a sand-like sodium fluosilicate finished product is obtained.

The solid electrolyte contains Na, M [alpha], M [beta], and F, where M [alpha] is at least one element that is a trivalent cation, and M [beta] is at least one element that is a tetravalent or higher cation. As a result, it is possible to provide a solid electrolyte having high ion conductivity. Preferably, M [beta] is an element having a tetravalent cation, the solid electrolyte contains a component represented by the compositional formula Na3-xM [alpha] 1-xM [beta] xF6, and 0 < x < 1 is satisfied.

The invention provides a quartz sand pickling waste liquid resourceful treatment method, which belongs to the field of industrial wastewater treatment, and comprises the following steps: adding a magnetic composite seed crystal into quartz sand pickling waste liquid, stirring, and carrying out magnetic separation; adding soluble potassium salt into the treated waste liquid to recover potassium fluosilicate; carrying out diffusion dialysis treatment on the filtrate to obtain recycled acid and dialysis residual liquid; the diffusion dialysis treatment adopts an asymmetric membrane, one surface of the asymmetric membrane is of a compact structure, the other surface of the asymmetric membrane is of a physical gradient of a loose structure, and one side of the compact structure of the asymmetric membrane is in contact with the waste liquid; and adding calcium oxide or calcium hydroxide into the dialysis raffinate for deep treatment and calcium recovery. The resource treatment method for the quartz sand pickling waste liquid is low in treatment cost, high in resource recovery rate and environmentally friendly, and quality-divided resource recovery of the quartz sand pickling waste liquid is achieved.

The invention discloses a solid-state battery material recovery method, and relates to the technical field of solid-state battery recovery, and the method comprises the following steps: heating first mixed powder in air to obtain second mixed powder; the second mixed powder is leached through organic weak acid and a reducing agent, first leaching residues and first leaching liquid are obtained, and then the first leaching liquid is processed through a wet process; the first leaching residues are leached with sulfuric acid, and second leaching residues and second leaching liquid are obtained; precipitating lanthanum oxalate from the second leaching solution to obtain a first mixed solution; precipitating lithium carbonate from the first mixed solution; the second leaching residues are leached with hydrofluoric acid, and third leaching liquid and carbon are obtained; precipitating zirconium oxalate from the third leaching solution to obtain a second mixed solution, and concentrating the second mixed solution to obtain fluosilicic acid. Through heating, step-by-step leaching, a wet process, precipitation separation and the like, valuable metals, silicon and carbon are efficiently separated and recycled, copper and aluminum impurities are removed, the resource utilization rate is effectively increased, and the feasibility of industrialization is remarkably improved.

This invention relates to heterovalent substituted argyrodite-type solid electrolytes. These solid electrolytes exhibit increased ionic conductivity.

This application relates to phosphor materials for light sources and methods for manufacturing the same. One method includes: mixing a first fluoride phosphor powder doped with tetravalent manganese with a processing solution for a specified time period; stopping the mixing to allow the fluoride phosphor powder to settle; removing at least some liquid that has separated from the first fluoride phosphor powder; repeating the steps of (a) mixing, (b) stopping the mixing, and (c) removing at least some of the liquid during one or more additional cycles; and obtaining a second fluoride phosphor powder after repeating the steps of mixing, stopping the mixing, and removing at least some of the liquid. The second fluoride phosphor powder contains a reduced amount of manganese compared to the first fluoride phosphor powder.

The present application relates to sewage treatment and water resource recycling technical field, especially to a kind of photovoltaic industrial park sewage treatment and recycling integrated pollution reduction water-saving method, including first pollution reduction water-saving strategy, pull rod slice production wastewater internal circulation, photovoltaic cell piece production wastewater internal circulation;Second pollution reduction water-saving strategy, after tail water treatment of park sewage treatment plant, as recycled water is provided to enterprise, for the production, life link of non pure water demand;After tail water treatment of sewage treatment plant, as recycled water is provided to enterprise, for pure water production;Third pollution reduction water-saving strategy, enterprise fluorine-containing wastewater, fluorine-free wastewater is treated by quality, and quality is transported to sewage treatment plant, so that sewage treatment plant reduces fluorine-containing wastewater treatment cost, while increasing fluorine-free recycled water volume, reduce the influence of photovoltaic industrial wastewater on water ecological environment.

Provided is an automatic method for producing a fluorine-containing crystalline product from a hydrofluoric acid solution, comprising: sensing the concentration of the hydrofluoric acid solution, and presetting a feeding flow rate; outputting a predetermined flow rate of the reaction solution by an automatic control module based on the concentration and the flow rate of the hydrofluoric acid solution and the concentration of the reaction solution; feeding the reaction solution and the hydrofluoric acid solution into the reaction area; sensing the in-situ fluoride ion concentration of the solution in the reaction area in real time, and controlling the feeding flow rate of the reaction solution in real time by the automatic control module; sensing the precipitation height of the fluorine-containing crystals in real time, and controlling whether to discharge the fluorine-containing crystals by the automatic control module. The method can be used to easily treat the hydrofluoric acid solution with a high concentration, accordingly obtaining sodium fluoroaluminate crystalline products or sodium fluorosilicate crystalline products with sand-like shape, low moisture content, and high sodium-to-aluminum ratio.

This application discloses a red phosphor, a method for manufacturing the same, and its use, and relates to the technical field of luminescent materials. The chemical composition of the red phosphor is A2M (1-x) F6:xMn 4+ (where A is at least one selected from alkali metal elements, M is at least one selected from Group 4 elements or Ti element, and the value range of x satisfies 0 < x ≦ 0.05). The red phosphor is in a particulate form, and the concentration of tetravalent manganese ions gradually decreases in the radial direction from the center of the red phosphor particles to its surface. In this application, due to the concentration of the activator Mn 4+ distributing in a descending gradient in the radial direction from the center of the red phosphor particles to its surface, the erosion of the phosphor powder by water vapor is buffered, its anti-aging property is improved, and the service life is further extended.

The invention belongs to the technical field of flue gas recovery, and provides a microwave radiation-based enhanced lithium leaching control process which comprises the following steps: predicting the concentrations of fluorides and sulfides by using a moving average method to avoid that the concentration of the fluorides exceeds the standard due to reaction lag, and determining the concentration of the fluorides by periodically analyzing the change trend of concentration data and setting a moving window. Different change stages of fluoride or sulfide concentration can be more accurately captured, the accuracy of prediction analysis is improved, the adjustment amount of spray liquid of the corresponding adjustment layer of the three-stage cross-flow spray tower is calculated by using a PID algorithm, the adjustment amount of spray liquid of other fine adjustment layers is calculated through a fluid mechanics model, and the requirements of fluorine and sulfur separation and recovery are met while the cost is reduced. According to the method, gas-liquid separation balance is kept, safe and stable operation of flue gas recovery is achieved, influence analysis of gas drag force is added, whether correction is conducted or not during spraying liquid flow adjustment is selected, and therefore flue gas recovery is achieved by improving the accuracy of spraying liquid flow adjustment and high quality.

The invention discloses a vertical graphene skeleton confinement silicon fluoride-based composite material as well as a preparation method and application thereof, and belongs to the field of inorganic materials. Putting Si into a tubular furnace, and heating to 1000-1200 DEG C at the speed of 10 DEG C / min in an argon environment; converting the atmosphere into a hydrogen / methane mixture for reaction to generate Si (at) G; then mixing and grinding the Si (at) G and tetrafluoroterephthalic acid, transferring the mixture to a tubular furnace, and finally performing heat treatment in an argon atmosphere to obtain a Si (at) G-F composite material; the composite material is of a core-shell type compact structure, and the surfaces of silicon particles are coated with vertically growing graphene sheets (VGs) in a self-adaptive mode to form a tightly-crosslinked three-dimensional network; dispersed sphere-like particles are formed, and the surfaces of the particles are tightly coated with the corrugated graphene sheet layers; the vertical graphene framework confinement silicon fluoride-based composite material Si (at) G-F composite material disclosed by the invention shows excellent electrochemical performance, and a feasible new way is provided for the development of high-energy-density lithium ion batteries.

One embodiment of the present invention relates to a porous silicon composite, a porous silicon carbon composite containing the same, and an anode active material, in which the porous silicon composite and the porous silicon carbon composite each contain both silicon particles and a magnesium compound, and have a molar ratio (O / Si) of oxygen (O) atoms to silicon (Si) atoms that satisfies a specific range, and by applying the porous silicon composite and the porous silicon carbon composite to the anode active material, it is possible to realize an excellent capacity retention rate, and to significantly improve the discharge capacity and initial efficiency.

This invention discloses a method for using circulating water from a wet-process phosphoric acid concentration system to improve the yield of fluorosilicic acid. The method includes the following steps: First, circulating water from a 58% ω(P₂O₅) concentrated phosphoric acid production system is pumped into a cooling system; the cooled circulating water is then pumped into the first and second fluorine absorption tanks of a 48% ω(P₂O₅) concentrated phosphoric acid production system. Second, the circulating water from the 48% ω(P₂O₅) concentrated phosphoric acid production system is used as makeup water for the 58% ω(P₂O₅) concentrated phosphoric acid production system. Finally, process water is pumped into the 48% ω(P₂O₅) concentrated phosphoric acid production system to replenish the water level. The method provided by this invention can effectively recover fluorine resources from the circulating water in the concentration system, improve the yield of fluorosilicic acid, reduce silica gel deposition in the 48% ω(P₂O₅) concentrated phosphoric acid production system, reduce cleaning workload, and continuously refresh the circulating water to reduce the corrosion rate of equipment and pipelines by HF. Furthermore, it can reduce the amount of circulating water discharged and the amount of calcium hydroxide used.

The invention discloses raw material mixing equipment for potassium fluosilicate preparation, and belongs to the technical field of potassium fluosilicate preparation, the raw material mixing equipment comprises a hollow base, a supporting frame is arranged at the top of the hollow base, a mixing barrel is arranged at the top of the supporting frame, a sealing cover plate is arranged at the top of the mixing barrel, and a first rotating shaft is arranged in the sealing cover plate; a first belt round head is fixedly connected to the outer side of the first rotating shaft, a second rotating shaft is movably connected to the interior of the sealing cover plate, a second belt round head is fixedly connected to the outer side of the second rotating shaft, a first bevel gear is fixedly connected to the bottom of the second rotating shaft, a sliding rail is fixedly connected to the surface of the bottom of the sealing cover plate, and a sliding rod is slidably connected to the interior of the sliding rail. An annular rack is fixedly connected to the bottom of the sliding rod, a first fixing plate is fixedly connected to the bottom of the annular rack, and a flow guide plate is fixedly connected to the bottom of the first fixing plate. The equipment is used for solving the problem that when the equipment mixes raw materials, the mixing efficiency of the surrounding raw materials is low, and conglomeration and wall adhesion phenomena are generated.

Multi-functional compounds of the structure: electrolyte compositions containing them, and electrochemical devices that utilize the electrolyte compositions.

The invention discloses a preparation method of a plasma-based Cl modified silicon negative electrode and a sulfur-based all-solid-state battery, and belongs to the technical field of batteries. The preparation method comprises the following steps: placing silicon with a preset mass into a plasma chamber, modulating the pressure in the plasma chamber into a preset pressure, and inputting chlorine-containing gas into the plasma chamber; the preset pressure is kept, and redundant air in the plasma chamber is emptied; generating plasma by adopting a radio frequency source, and treating the silicon powder for preset time; the plasma acts on the chlorine active group, the plasma bombards the surface of the silicon, the chemical reaction activity of surface atoms is activated, the chlorine active group and the silicon atoms are promoted to be subjected to an in-situ bonding reaction, a Si-Cl covalent bond modification layer is constructed, and the surface Cl modified silicon negative electrode is obtained. The transfer behavior of electrons at the interface to the sulfide electrolyte is limited, and the reductive decomposition problem of the sulfide solid electrolyte is inhibited, so that the sulfenyl all-solid-state battery with good performance is constructed.

The application discloses a method for removing fluorine from white fertilizer by dry method and preparing fluorosilicic acid, which comprises the following steps: adding dried white fertilizer into a reaction container, mixing the white fertilizer with silicon powder and sulfuric acid under stirring, wherein the mixing ratio is that the molar ratio of SiO2 / F is 0.3-0.8 and the molar ratio of H2SO4 / F is 1-4; then conveying the mixed material to a calcining furnace for calcination; introducing fluorine-containing gas discharged from the calcining into a fluorosilicic acid preparation system, and obtaining fluorosilicic acid products with a purity of greater than or equal to 12 % through two-stage spray absorption; and continuing to use the fluorine-removing calcined slag as white fertilizer. The application can significantly improve the fluorine resource utilization rate and reduce resource waste; meanwhile, by adding sulfuric acid which has the dual functions of raw material and catalyst, the reaction temperature is effectively reduced, the energy consumption and equipment cost are reduced, and the reaction efficiency and process economy are further improved.

An automated production method is provided for producing fluorine-containing crystalline products using a hydrofluoric acid solution. [Solution] The method comprises sensing the concentration of the hydrofluoric acid solution and pre-setting the supply flow rate; an automatic control module outputting a predetermined flow rate of the reaction solution based on the concentration and flow rate of the hydrofluoric acid solution and the concentration of the reaction solution; supplying the reaction solution and the hydrofluoric acid solution to the reaction zone; sensing the fluoride ion concentration of the solution in the reaction zone in real time and controlling the supply flow rate of the reaction solution in real time by the automatic control module; and sensing the precipitation height of the fluorine-containing crystals in real time and controlling whether or not to discharge the fluorine-containing crystals by the automatic control module. The present invention makes it possible to obtain granular sodium fluoroaluminate crystals or sodium fluorosilicate crystals with low water content and high Na / Al molecular ratio by processing a high-concentration hydrofluoric acid solution in a simple manner.

The invention discloses a method for recovering fluorine in a white fertilizer and preparing a slow-release nitro fertilizer at the same time, and belongs to the technical field of clean processing and utilization of phosphorus resources. The white fertilizer is subjected to fractional acidolysis by using nitric acid, and the phosphorus-containing filtrate subjected to preliminary acidolysis is low in impurity content and can be used for preparing water-soluble ammonium phosphate. And the residual acidolysis residues are subjected to complete acidolysis, phosphorus and fluorine elements are completely leached and then defluorination is performed, fluorine is precipitated in the form of fluosilicate, and a fluosilicate product can be obtained through further separation. According to the method, phosphorus and fluorine resources in the white fertilizer are comprehensively utilized, and clean processing and utilization of the phosphorus resources are achieved. The method is simple in whole process implementation method and low in production cost, and phosphorus and fluorine resources in the white fertilizer are fully recycled.

According to one aspect of the present disclosure, a method of producing purified silicon comprises providing an alkali or alkaline earth metal and a metallic or aminated halide salt of silicon; combining the alkali or alkaline earth metal and metallic or aminated halide salt of silicon in a liquid medium to form a precipitate; combining the precipitate with sulfuric acid or another acid to form a byproduct and silicon; and recovering the purified silicon. In some embodiments, the liquid medium is an amine or ammonia. In some embodiments, the alkali or alkaline earth metal and metallic or aminated halide salt of silicon are combined at a low temperature such that the amine or ammonia are in a liquid phase.

The invention discloses a method for recovering fluorine from fluorine-containing dilute sulphuric acid. Silicon tetrafluoride is obtained through chemical reaction of silicon dioxide and hydrogen fluoride in dilute sulphuric acid, the silicon tetrafluoride is released in a gas form and is blown back into a hydrogen fluoride system through a fan, the silicon tetrafluoride reacts with water in the system to generate fluosilicic acid, and the fluosilicic acid is a raw material for preparing anhydrous hydrogen fluoride, so that the yield of the anhydrous hydrogen fluoride is improved. And the fluosilicic acid is decomposed again in the hydrogen fluoride system to generate hydrogen fluoride, so that fluorine recovery is realized.