JP5291098B2 - Technology for the production of polycrystalline silicon from fluorosilicic acid solution and equipment for its production - Google Patents

Abstract

The invention relates to metallurgy and/or chemistry, in particular to methods and devices for producing a silicon tetrafluoride gas and polycrystalline silicon from said silicon tetrafluoride gas. The method for producing silicon tetrafluoride from a hydrosilicofluoric acid solution consists in forming, washing, drying and decomposing the acid extract and in bubbling a nonseparated silicon tetrafluoride and hydrogen fluoride flow through silicon dioxide. The silicon producing method consists in interacting the silicon tetrafluoride gas with magnesium vapour and in subsequently separating a final product. Said invention makes it possible to produce a highly pure silicon, to increase the final produce yield, to improve the environmental friendliness of the production, to simplify the silicon production process and to reduce the production cost of the final product.

Description

  The present invention relates generally to metallurgy and / or chemistry, and more particularly to the production of “solar grade” polycrystalline silicon in the form of spherical powders from wastes of phosphorus production, particularly from fluorosilicate solutions. It is related with technology and equipment to do.

Today, there is a lot of interest from all over the world in developing alternative energy fields, including solar energy. Photoelectric device manufacturing has increased from 1200 MW to 1727 MW worldwide during 2004-2005. However, further growth in solar cell manufacturing is limited by the shortage of silicon (including “solar grade” silicon) and by the high cost and ecological problems arising from its manufacturing technology . According to data from the European Photovoltaic Industry Association (EPIA), global solar energy share will be 15-20% by 2015 and silicon production will increase to 200,000 tons.

In industrial-scale silicon production, the fine silicon powder is obtained with anhydrous chlorine hydride by hot carbon reduction of quartzite [patent application No. RU No. 2003125002/15, МПК ⁷ C01 B9 / 00, published on 10.03.2005]. Techniques based on fluoride-hydride technology are known by purifying chlorosilanes, followed by chlorosilanes formed in the chlorination process, through adjustment to the required purity level. These silicon manufacturing technologies are multi-stage, consume energy, produce low commercial products, and have a large amount of impurities, so that reasonable prices cannot be obtained for manufactured polycrystalline silicon (known The market price of “solar grade” polycrystalline silicon manufactured with technology is $ 20 per kilogram).

  For example, a technique for producing silicon by reducing silicon from silicon tetrafluoride produced by fluorination of silicon dioxide is known [Patent RU 2272755C1, published on March 27, 2006, application WO 2005 / 021431A1, 2005 Released March 10]. The disadvantages of the process for producing tetrafluoride from silicon dioxide are large amounts of impurities and high energy consumption.

  The raw cost of polycrystalline silicon is determined primarily by the cost of raw materials, technical consumables, energy consumption and costs for providing ecologically and technically safe products. The condition for lowering the cost of silicon is the use of certain environmentally hazardous technical sub-extracts / chemical manufacturing wastes in the raw materials used in their production, It occurs in tens of thousands of tons annually within the territories of the USA, Canada, CIS countries (eg Belarus and Ukraine), Romania, the Czech Republic, and other countries.

For example, apatite-treated secondary products in fertilizer production, particularly fluorosilicic acid (H ₂ SiF ₆ ), can be used as a raw material for silicon tetrafluoride production.

A process for producing silicon tetrafluoride from a fluorosilicic acid solution comprising the generation of fluosilicate, its washing, drying and subsequent decomposition to form gaseous silicon tetrafluoride and hydrogen fluoride, followed by A method is known which consists of separating the final product [patent RU 2046095C1 МПК ⁶ CO1B33 / 10, published 20 October 1995].

The disadvantages of this method are as follows. That is, after the step of decomposing the fluosilicate, the two generated gaseous products (these are silicon tetrafluoride (SiF _4gas ) and hydrogen fluoride (HF _gas )) at −78 ° C. Separated by HF cold condensation. This process of separating silicon tetrafluoride and hydrogen fluoride requires additional low temperature equipment and high energy consumption, complicating the technical process, and the cost of the final product, i.e. silicon tetrafluoride. Cost increases.

  A process for producing silicon tetrafluoride is known in which fluorosilicic acid is decomposed into silicon tetrafluoride and hydrogen fluoride by heating to a temperature of 112 ° C., and then the gas mixture is passed through silicon dioxide [patents] GB 1009564, published November 10, 1965].

  The disadvantage of this method is that the fluorosilicic acid decomposition is carried out by heating which increases energy consumption. By flowing a gas mixture of silicon tetrafluoride and hydrogen fluoride through silicon dioxide, additional silicon is generated by the interaction of the dioxide and hydrogen fluoride, but there is also the generation of water that must be excluded from the reaction zone. Cause additional operations.

  A method for producing silicon tetrafluoride by the interaction of hydrogen fluoride with silicon dioxide immersed in concentrated sulfuric acid to exclude water from the reaction zone is known [Patent JP 57135711, published Aug. 21, 1982] .

  However, this method is used for tetrafluoride production, and in the claimed method, an unseparated mixture of hydrogen fluoride and tetrafluoride is flowed into silicon dioxide in the presence of fuming sulfuric acid. This results in an increase in tetrafluoride output from fluorosilicic acid.

  A method of reducing silicon from silicon dioxide with magnesium vapor is known [patent RU 2036143 C1 МПК6 CO1B33 / 023, published May 27, 1995]. The disadvantage of this method is that silicon dioxide is used as a raw material for silicon reduction, which produces silicon containing large amounts of impurities.

A method for producing silicon is known [Patent RU 2035397C1 МПК ⁶ CO1B 33/02, published May 20, 1995], which involves the interaction of a fluorosilicon-containing compound with a reducing agent. A disadvantage of this method is that atomic hydrogen is used during silicon reduction, and a high degree of safety is required for production.

  A method for producing silicon by the interaction of silicon tetrafluoride with a group 1 or group 2 metal, particularly magnesium, is known [WO 03059814 A, published 24 July 2003].

  The disadvantage of this method is that amorphous silicon is produced.

  Production facilities for polycrystalline silicon including an immersion chamber are known [Patent RU 2224715 C1, published 27 February 2004]. The disadvantage of this equipment is that it is designed to be produced by continuously reducing silicon from trichlorosilane with hydrogen and is not applicable to the process for producing silicon from fluorosilicic acid solutions.

  Equipment for the production of polycrystalline silicon is known [Patent RU 2066296 C1, published on Sep. 10, 1996], but this equipment is not capable of producing silicon from a fluorosilicic acid solution. Has the same drawbacks.

  An object of the present invention is to provide a method for continuously producing solar grade polycrystalline silicon from a fluorosilicic acid solution for the purpose of reducing the cost of the final product.

  The technical results achieved by implementing the claimed invention group are as follows: from fluorosilicic acid solution, adapted to “solar grade” silicon by its impurity characteristics Production of polycrystalline silicon, increased production of final product (polycrystalline silicon) due to increased production of silicon tetrafluoride, and generation of by-products (mainly hydrofluoric acid) The technical process of silicon tetrafluoride production is improved because the environmental conservation characteristics of the production process are improved for immediate use in the technical process, and the silicon tetrafluoride and hydrogen fluoride separation process is eliminated. Simplified, reduced energy consumption due to the use of low temperature reactions for silicon reduction, and its impurity characteristics make it suitable for “solar grade” silicon An integrated technical process for producing polycrystalline silicon, mainly in the form of a spherical powder, from a fluorosilicic acid solution is to be developed.

  The above benefits greatly reduce the cost of producing polycrystalline silicon (up to $ 10 per kilogram) while maintaining high purity (99.99% to 99.999%) and impurity content suitable for use in the solar energy sector. Can be made.

The intended technical result is that the following characteristics of the technology for producing polycrystalline silicon from a fluorosilicic acid solution, namely the interaction of fluorosilicic acid with an organic base solution, lead to an organic-soluble fluosilicate from the fluorosilicic acid solution. Generating salt,
Drying the generated fluosilicate with air or an inert gas stream heated to a temperature of 55-60 ° C.,
-Producing gaseous silicon tetrafluoride from fluosilicate,
-Producing gaseous silicon tetrafluoride by decomposing fluorosilicate into gaseous silicon tetrafluoride and hydrogen fluoride;
Flowing the generated gaseous silicon tetrafluoride and hydrogen fluoride through silicon dioxide immersed in fuming sulfuric acid without separation;
-Reducing silicon from the generated gaseous silicon tetrafluoride with magnesium vapor at a temperature below 1000 ° C,
Separating the product which is a mixed powder of silicon and magnesium fluoride and simultaneously obtaining polycrystalline silicon in the form of a spherical powder;
Achieved by separating the produced polycrystalline silicon from magnesium fluoride.

  High purity polycrystalline silicon can be produced by a series of technical operations in which the product formed in the previous operation is a raw material for the next operation. The production of organic soluble fluosilicates results in the formation of particularly pure silicon tetrafluoride. The drying of the fluosilicate facilitates the technical process.

In a bubbling reactor filled with silicon dioxide soaked in fuming sulfuric acid, by bubbling _unseparated SiF _4gas and HF _gas gas streams, for example by neutralization of hydrogen fluoride, SiF _gas and silicon dioxide Although not interacting, HF _gas begins to interact with the formula SiO ₂ + _{4HF gas} = SiF _4gas + H ₂ O, which results in the formation of additional gaseous silicon tetrafluoride and the total production of silicon tetrafluoride. Increase the amount.

Thus, bubbling _unseparated SiF _4gas and HF _gas gas streams through silicon dioxide produces only gaseous SiF ₄ free of impurities and increases Si yield. Further reduction of silicon tetrafluoride (SiF _4gas ) from SiO _{2 in} the presence of HF increases the total output of SiF _4gas , while at the same time using hydrogen fluoride immediately in the technical process, The separation process of silicon tetrafluoride and hydrogen fluoride, which would require technical conditions to use and consume high energy, is eliminated from the technical process.

  The presence of fuming sulfuric acid removes the water produced by the reaction and eliminates additional technical operations therefor.

  Silicon reduction at temperatures below 1000 ° C reduces energy consumption and improves the safety of the manufacturing process.

By separating the product, which is a mixed powder of silicon and magnesium fluoride, polycrystalline silicon in the form of a spherical powder can be obtained at the same time, an additional operation is required to convert amorphous silicon to crystalline silicon The cost is reduced, process continuity is achieved, and large spherical crystals can be easily separated from the magnesium fluoride powder.

  Furthermore, in a special embodiment of the invention, the fluosilicate (extract) is washed and then decomposed.

  Furthermore, in a special embodiment of the invention, a solution of trialkylamine, or a solution of trialkylamine dissolved in triethylbenzene, or a solution of trialkylamine in a mixture of dodecane and octyl spirit is used as the organic base. use.

  Furthermore, in a special embodiment of the invention, it is preferred to decompose the sol (extract) by treatment with concentrated mineral acid.

  Furthermore, in a special embodiment of the invention, it is reasonable to use fuming sulfuric acid (containing 3-5% by weight free sulfuric anhydride) as the mineral acid.

  Furthermore, in a special embodiment of the invention, it is recommended to immerse silicon dioxide in a 4-7% fuming sulfuric acid solution.

  Furthermore, in a special embodiment of the invention, it is preferred to use silica sand as silicon dioxide.

  Furthermore, in a special embodiment of the invention, the step of separating the reaction mixture and at the same time obtaining silicon in the form of a spherical powder is carried out by centrifugal disruption.

  Further, in a special embodiment of the invention, centrifugal disruption is the mixing of silicon and magnesium fluoride powder into a rotating crucible placed in a melting furnace where the mixture is placed between the crucible and the non-melting electrode. Exposure to a plasma arc formed between them.

  Furthermore, in a special embodiment of the invention, it is recommended to carry out the centrifugation in an inert gas.

  Furthermore, in a special embodiment of the invention, the reduction of silicon is carried out in the presence of an inert gas, which carries the silicon tetrafluoride to the immersion chamber and vortexes the resulting extract. Transport from container.

  Furthermore, in a special embodiment of the invention, it is reasonable to use argon as the inert gas.

  Furthermore, in a special embodiment of the invention, magnesium vapor is sent from the vacuum evaporator to the vortex reactor.

  Furthermore, in a special embodiment of the invention, polycrystalline silicon is produced in the form of spherical silicon powder having a particle size of mainly 0.3 mm to 0.6 mm.

  Furthermore, in a special embodiment of the invention, the silicon spherical powder is washed with distilled water and twice distilled water.

In order to carry out the technology for producing polycrystalline silicon in the form of spherical powder from a fluorosilicic acid solution and to achieve the objective and claimed technical results, the polycrystalline silicon is continuously produced in the form of spherical powder from a fluorosilicic acid solution. It is preferred to use equipment that is manufactured automatically. This equipment consists of a unit connected by a pipeline system for extracting a fluorosilicic acid solution in the presence of an extractant, a unit for drying the produced extract, acid-treating the extract, Unit to form silicon fluoride and hydrogen fluoride, unit to neutralize hydrogen fluoride to form silicon tetrafluoride, unit to generate magnesium vapor from magnesium melt, silicon vapor to silicon tetrafluoride with silicon vapor It consists of a unit for carrying out the reduction, a unit for separating the reaction mixture of silicon and magnesium fluoride powder and simultaneously obtaining silicon in the form of spherical powder, and a unit for separating silicon and magnesium fluoride in the form of spherical powder.

  Furthermore, in a special embodiment of the invention, the unit for extracting the fluorosilicic acid solution comprises at least one centrifugal extraction device.

  Furthermore, in a special embodiment of the invention, the unit for drying the extract comprises at least one foam dryer with a heat exchange device.

  Furthermore, in a special embodiment of the invention, the unit for acid treating the extract to form gaseous silicon tetrafluoride and hydrogen fluoride comprises at least one centrifugal extractor.

  Furthermore, in a special embodiment of the invention, the unit for performing hydrogen fluoride neutralization and forming silicon tetrafluoride comprises at least one foaming reactor filled with silicon dioxide.

  Furthermore, in a special embodiment of the invention, a protective coating is applied to the centrifugal extractor and the foam dryer.

  Furthermore, in a special embodiment of the invention, the protective coating is based on a fluoroplastic.

  Furthermore, in a special embodiment of the invention, at least one vacuum evaporator is used as a unit for generating magnesium vapor from the magnesium melt.

  Furthermore, in a special embodiment of the invention, at least one vortex reactor is used as the immersion chamber for silicon reduction.

  Furthermore, in a special embodiment of the invention, the vacuum evaporator and the vortex reactor are provided with a protective lining.

  Furthermore, in a special embodiment of the invention, the vortex reactor is equipped with a vacuum pump.

  Furthermore, in a special embodiment of the invention, the vortex reactor is equipped with a heating device.

  Furthermore, in a particular embodiment of the invention, the final product separation unit includes at least one tank filled with a fluid having a density not exceeding that of silicon.

  Furthermore, in a special embodiment of the invention, the unit for producing silicon in the form of a spherical powder comprises a crucible (rotatable) and an electrode, in which a plasma arc is maintained between the crucible and the electrode. including.

  Furthermore, in a special embodiment of the invention, the electrode is non-meltable.

  Furthermore, in a special embodiment of the invention, the unit for separating the final product is in the form of a vibrating table.

  Furthermore, in a special embodiment of the invention, the facility for producing polycrystalline silicon further comprises a melting furnace for producing silicon in an ingot.

  Furthermore, in a special embodiment of the invention, a unit for cooling the mixture resulting from the reduction reaction.

  Furthermore, in a special embodiment of the invention, the installation further comprises a silicon packaging line.

The above and other features and advantages of the present invention will now be described in a preferred embodiment with reference to the accompanying drawings.
It is a common arrangement of production equipment for polycrystalline silicon in the form of spherical powder. It is a general flowchart which shows the manufacturing method of the polycrystalline silicon in the form of spherical powder.

  The production of polycrystalline silicon in the form of a spherical powder from a fluorosilicic acid solution is preferably carried out in two main technical steps.

In a first technical step, gaseous silicon tetrafluoride is produced from a hydrosilicofluoric acid (H ₂ SiF ₆ ) solution in an assembly for producing silicon tetrafluoride from a silicohydrofluoric acid solution. This assembly is connected with a pipeline system and contains the following units with stop valves: an aqueous fluorosilicic acid solution (H ₂ SiF ₆ ) comprising at least one centrifugal extractor with a protective fluoroplastic cover. Unit 1 for extraction, comprising a protective fluoroplastic cover, including at least one bubbling dryer equipped with a heat exchange device, unit 2 for drying the produced extract, at least one comprising a protective fluoroplastic cover Including a centrifugal extractor based on unit 3, acid-treating the extract to generate gaseous silicon tetrafluoride and hydrogen fluoride, with a protective fluoroplastic cover, eg silicon dioxide (quality using silica sand) Including at least one bubbling reactor packed with Neutralize the hydrogen, comprising units 4 for generating the additional silicon tetrafluoride. Using the above assembly, silicon tetrafluoride is produced from a fluorosilicic acid solution by the following technique .

In unit 1, an aqueous solution of silicofluoric acid (H ₂ SiF ₆ ) (preferably 20% concentration) is added with an organic base solution (extractant), for example with a solution of trialkylamine (TAA) or with trialkylamine. Processed to produce an extract with a solution dissolved in ethylbenzene or with a solution of trialkylamine in a mixture of dodecane and octyl spirit, for example organic solubility such as (TAAH) ₂ SiF ₆ A sol (extract) is produced. After extraction and phase precipitation are complete, the resulting hydrosilicofluoric acid extract is separated from the liquid phase, washed with aqueous HF solution, unit 2 (a bubbler with a protective fluoroplastic cover and a heat exchanger. And dried with a stream of air or inert gas heated to a temperature of 55-60 ° C. The extract is then acid treated and treated with _{concentrated mineral} acid (mainly fuming sulfuric acid) containing 3-5% anhydrous sulfuric acid in unit 3 for generating gaseous silicon tetrafluoride SiF _4gas and hydrogen fluoride HF _gas. To do. The liquid phase obtained from this operation is returned to the extraction step. The gaseous products of fluorosilicate decomposition, namely SiF _4gas and HF _gas, are produced in unit 2 by the following reaction (when using a trialkylamine solution as extract).
_{(TAAH) 2 SiF 6 + nH} 2 SO 4 → SiF 4gas + 2HF gas + (TAAH) 2 SiO 4 (H 2 SO 4) n-1
After gas evolution and phase precipitation are complete, the organic phase is separated from the liquid phase followed by thorough washing with water and aqueous sodium hydroxide to complete the extraction of H ₂ SO ₄ . The regenerated extractant is returned to the H ₂ SiF ₆ extraction process. Gaseous products produced by fluorosilicate decomposition, namely silicon tetrafluoride (SiF _4gas ) and hydrogen fluoride (HF _gas ), without separation, neutralize the hydrogen fluoride and _provide additional tetrafluoride. A unit 4 is provided with a protective fluoroplastic cover for the production of silicon hydride and is composed of a composition neutralizing hydrogen fluoride, for example at least one bubbler filled with silicon dioxide, which is preferred for quality silica sand. To the containing unit 4.

Gaseous silicon tetrafluoride (SiF _4gas ) does not interact with silicon dioxide when bubbling through silicon dioxide (SiO ₂ ), but the reaction 4HF _gas + SiO ₂ → SiF ₄ ↑ + 2H ₂ O adds additional gaseous Manufactures silicon tetrafluoride (SiF _4gas ), increasing the total output of silicon tetrafluoride. Simultaneously with the increase in the total production of gaseous silicon tetrafluoride, harmful products such as hydrogen fluoride (hydrofluoric acid) are immediately neutralized in the process.

Organic fluosilicates (extracts) can also be produced by a continuous countercurrent extraction process. In order to carry out the preferred method of carrying out the present invention, the unit 1 uses a countercurrent extraction device in which at least 6 to 5 steps are performed to extract H ₂ SiF ₆ and the sixth step is to wash the extract. It is reasonable to do. The fluorosilicic acid extract produced in the last step is dried with a stream of air or inert gas heated to a temperature of 55-60 ° C. and concentrated mineral acid (mainly fuming sulfuric acid) containing 3-5% anhydrous sulfuric acid Process with.

  After the production of gaseous silicon tetrafluoride by increasing the yield of silicon and low impurity content by the above method, the next technical process, namely the gaseous silicon tetrafluoride produced in the previous process, is produced. Perform silicon reduction.

In order to produce polycrystalline silicon that conforms to the announced features in impurity content and price, the polycrystalline silicon production facility shown in Fig. 1 is used, and by using this facility, the polycrystalline silicon shown in Fig. 2 is used. It is preferable to implement manufacturing techniques .

The facility for continuous production of polycrystalline silicon from fluorosilicic acid (Figure 1) is connected by a pipeline system and is equipped with the following units with stop valves: at least one centrifuge with a protective fluoroplastic cover. A manufactured extraction comprising a unit 1 for extracting an aqueous fluorosilicic acid solution (H ₂ SiF ₆ ), including an extraction device, comprising a protective fluoroplastic cover and comprising at least one bubbling dryer equipped with a heat exchange device A unit 2 for drying things, a unit 3 for producing gaseous silicon tetrafluoride and hydrogen fluoride by acid treatment of the extract, comprising at least one centrifugal extraction device with a protective fluoroplastic cover, protection At least one bubbling with a fluoroplastic cover, for example filled with silicon dioxide (silica sand) Unit 4 comprising a reactor, neutralizing hydrogen fluoride and generating additional silicon tetrafluoride, including at least one vacuum evaporator with protective lining and generating magnesium vapor from the magnesium melt 5. Unit 6 for reducing silicon from silicon tetrafluoride with magnesium vapor, using a vacuum pump for collecting air from the chamber and at least one vortex reactor equipped with a unit for heating the reaction chamber A unit 7 for cooling the reaction mixture formed by reduction, a unit 8 for separating the reaction mixture into silicon and magnesium fluoride powders and obtaining spherical silicon powder at the same time, a unit for separating spherical silicon powder and magnesium fluoride 9 is included. The protective fluoroplastic cover protects the device from aggressive media during operation and extends its useful life. The number of units required is determined by the capacity of the equipment and is calculated based on the acid to be processed and the amount of silicon produced.

  In addition, this equipment is not directly involved in the silicon production process, but is a unit that performs support operations, such as a silicon packaging line, a magnesium fluoride packaging line, a line for producing gypsum from extractant regeneration solution (not shown) May be provided.

The generated silicon tetrafluoride is sent from the unit 4 to the immersion chamber 6 for silicon reduction, using at least one vortex reactor equipped with a vacuum pump and a heating device. Simultaneously with silicon tetrafluoride, magnesium vapor is sent from unit 5 to immersion chamber 6. After evacuating the air with a vacuum pump, the immersion chamber 6 is heated to a temperature of 670-800 ° C. Gaseous silicon tetrafluoride interacts with magnesium vapor, and a reaction mixture which is a mixed powder of silicon (Si) and magnesium fluoride (MgF ₂ ) is produced by the reduction reaction SiF _4gas + Mg _gas = Si + MgF ₂ . The product formed as a result of the reduction reaction is cooled in the cooling unit 7. Thereafter, the silicon powder (Si) is separated from magnesium fluoride (MgF ₂ ). In order to remove the reaction mixture from the immersion chamber 6, a “carrier” gas, ie argon, which flows into the immersion chamber 6 simultaneously with the gaseous silicon tetrafluoride is used. In a preferred embodiment of the invention, it is reasonable to produce silicon in the form of a commercial product, i.e. in the form of a spherical powder. In view of the fact that silicon melt and magnesium fluoride melt have different properties, inert gas is used to efficiently separate the resulting mixture and at the same time convert silicon to market quality (spherical powder) Centrifugal disintegration in the medium is a preferred choice for silicon production in the form of spherical powder. To perform the centrifugal disintegration method, the unit 8 includes a melting furnace with a rotatable crucible and a non-melting electrode and holding a plasma arc between the crucible and the electrode. A mixture of silicon and magnesium fluoride is sent to a rotating crucible and exposed to the heat of a plasma arc formed between the crucible and the non-melting electrode. Under the action of the heating arc, the silicon and magnesium fluoride begin to melt and the molten material is pushed out of the crucible edge by centrifugal force and dropped from the crucible in the form of separate drops of silicon and magnesium fluoride. The melt droplets solidify in the form of separated spherical particles in an inert atmosphere before impacting the chamber walls and maintain this sphere in the solid phase. Since the magnesium fluoride particles are 1.3 to 1.5 times smaller than the size of the obtained silicon spherical powder, the silicon powder can be separated with high accuracy by the unit 9 (for example, a vibration table). The produced spherical silicon powder having a particle size mainly in the range of 0.3 to 0.6 mm is washed with distilled water and twice distilled water.

  Accordingly, by carrying out the claimed invention, it is possible to remove polycrystalline silicon from a fluorosilicic acid solution, i.e. polycrystalline silicon in the form of a spherical powder having a high level of purity (99.99%). Compared to the technical aspect of this technology, the production of the final product can be increased and it can be continuously manufactured at a low cost.

Claims (16)

A method for producing polycrystalline silicon from a fluorosilicic acid solution comprising:
-Production of organic soluble fluosilicate from fluorosilicic acid solution by interaction of fluorosilicic acid and organic base,
-Drying the obtained fluosilicate with air or inert gas at a temperature of 55-60 ° C,
-Producing gaseous silicon tetrafluoride from fluosilicate,
-Producing gaseous silicon tetrafluoride by decomposing fluorosilicate into gaseous silicon tetrafluoride and hydrogen fluoride;
Flowing the produced gaseous silicon tetrafluoride and hydrogen fluoride through silicon dioxide in the presence of fuming sulfuric acid without separation;
-Reducing silicon from the generated gaseous silicon tetrafluoride with magnesium vapor at a temperature below 1000 ° C,
-Separating the reduction product, which is a mixture of silicon and magnesium fluoride powder, simultaneously forming polycrystalline silicon in the form of a spherical powder;
- polycrystalline silicon produced and separating from magnesium fluoride, method. The process according to claim 1, wherein the step of separating the reaction mixture and simultaneously obtaining silicon in the form of a spherical powder is carried out by centrifugal disruption. In the centrifugal disintegration method, a reaction mixture of silicon and magnesium fluoride powder is sent to a rotatable crucible placed in a melting furnace, and the mixture is formed between the crucible and the non-melting electrode. The method of claim 2, wherein the method is exposed to a plasma arc. The method according to claim 3, wherein the centrifugal disruption is performed in an inert gas atmosphere. The process according to claim 1, wherein the silicon reduction is carried out in a vortex reactor. The method of claim 1, wherein magnesium vapor is sent from a vacuum evaporator to a vortex reactor. The process according to claim 1, wherein the polycrystalline silicon is produced in the form of a spherical powder having a particle size mainly in the range of 0.3 mm to 0.6 mm. An apparatus for producing polycrystalline silicon in the form of spherical powder from a fluorosilicic acid solution, connected by a pipeline system,
A unit for extracting the fluorosilicic acid solution,
A unit for drying the produced fluorosilicic acid extract,
A unit for decomposing the extract and generating gaseous silicon tetrafluoride and hydrogen fluoride,
A unit for neutralizing hydrogen fluoride and generating silicon tetrafluoride,
A unit for generating magnesium vapor from the magnesium melt,
A unit for reducing silicon from gaseous silicon tetrafluoride in the presence of magnesium,
A unit for separating the reaction mixture and at the same time obtaining silicon in the form of a spherical powder;
An installation characterized in that it comprises a unit for separating the final product.   The installation according to claim 8, wherein the unit for extracting the fluorosilicic acid solution comprises at least one centrifugal extractor.   9. The installation according to claim 8, wherein the unit for drying the extract comprises at least one bubbling dryer with a heat exchange device.   9. The facility of claim 8, wherein the unit for decomposing the extract and generating gaseous silicon tetrafluoride and hydrogen fluoride comprises at least one centrifugal extraction device.   9. An installation according to claim 8, wherein the unit for neutralizing hydrogen fluoride and generating silicon tetrafluoride comprises a bubbling reactor filled with at least one silicon dioxide.   The installation according to claim 8, wherein at least one vacuum evaporator is used as a unit for generating magnesium vapor from the magnesium melt.   9. The installation according to claim 8, wherein at least one vortex reactor is used as the unit for silicon reduction. To produce silicon in the form of a spherical powder, units for separating the reaction mixture, comprising a rotatable Ruth Boo and electrodes arranged in a melting furnace, a plasma arc is maintained between the crucible and the electrode The equipment according to claim 8.   The facility of claim 15, wherein the electrode is non-meltable.

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