RU2525415C1 - Production of silicon and its compounds and production line to this end - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: proposed line comprises fluo(ro)silicic acid production unit (6), extraction unit (5) with absorption tower (1) to trap silicon tetrafluoride and anhydrous hydrogen fluoride and condenser (2) for their separation, gas cylinder station (3) to store and transfer gases and play of silicon compounds synthesis (10) including system (7) to feed gases into reactor (7). Reactor top is arranged in resistance furnace (12) to form heating zone (13) therein while reactor bottom is connected with intake bin (18) to collect synthesised particles in removable container (17). Bin top accommodates filter (15) to discharge gas into absorption column. Reactor (7) bottom and bin (18) top are equipped with water and air cooling system (14). To produce polycrystalline silicon, this line incorporates extra gas cylinder station (8) for storage and transfer of monosilane and reaction gas and monosilane decomposition station (9) with second reactor (7').

EFFECT: enhanced performances, stable output of high-purity product, non-polluting process, lower power input.

30 cl, 2 dwg, 2 tbl, 12 ex

Description

The present invention relates to the field of metallurgy and chemistry, in particular to the production of metallic silicon and its compounds, and can be used in mechanical engineering, non-ferrous metallurgy, chemical and glass industry, medical technology, jewelry, high-tech industries, such as the manufacture of semiconductor materials for electronic industry and solar energy.

Silicon and its compounds are the most important materials for the production of electronic devices and solar cells, as well as the starting materials for creating coatings and functional layers.

Ultrapure silicon (Si) is the main semiconductor material of electronic equipment and is used, for example, for the production of single electronic devices, microcircuits, functional elements of solar cells, etc. Due to its properties, silicon carbide (SiC) is widely used in the production of power semiconductor devices, heterostructure devices based on SiC polytypes, and also as a high-temperature abrasive material. Silicon nitride (Si ₃ N ₄ ) is used in the manufacture of electronic products, in particular for producing dielectric layers, and also as a high-temperature abrasive material. Silicon dioxide (SiO ₂ ), depending on the polytype, is the base material of the glass, electronic and optical industries and is used in the manufacture of almost all optical products, including optical fiber fibers, components of laser and traditional optics, and also as a filler in the paint and varnish and rubber industry. Crystalline quartz has piezoelectric properties and is therefore used in electronics, radio engineering, ultrasonic installations, and is used in the production of quartz resonators and piezoelectric sensors.

The methods for producing silicon and its compounds are very diverse, and therefore the development of an economical, environmentally friendly technology for producing silicon compounds and pure silicon is still an urgent problem.

Polycrystalline silicon carbide is obtained in electric furnaces at a temperature of 1800-2300 ° C by reducing silicon dioxide with carbon. Pure silicon carbide can be obtained by sublimation of powdered silicon carbide in an argon atmosphere at 2500 ° C. Due to the high temperature and pressure values necessary for the melting of silicon carbide, the classical methods for producing SiC single crystals are not applicable; therefore, they are grown by growing SiC crystals from the gas phase or from melts.

Silicon nitrides can be obtained by direct nitriding of silicon at a temperature of about 1500 ° C, thermocarbon nitriding, and the interaction of silicon compounds with ammonia.

Synthetic silicon dioxide is obtained by heating silicon to a temperature of 400-500 ° C in an oxygen atmosphere, thermal oxidation at high temperatures.

All of the known technologies for producing silicon compounds listed are carried out under conditions of high-temperature reactions, require sophisticated equipment, which increases the cost of the finished product. In addition, for each of the produced silicon compounds, their own equipment is used.

Known technologies for producing silicon compounds, in particular silicon hydride (monosilane), based on the catalytic dismutation of trichlorosilane followed by separation of reaction products and purification of monosilane (RU 2403964 C2, B01J 8/02, 11/20/2010). These methods, known as various modifications of the Siemens Process, require significant energy consumption, are multi-stage and generate a significant amount of waste.

A known method for producing silicon compounds, in particular monosilane, by catalytic disproportionation of trialkoxysilane obtained by the esterification of chlorosilanes with an organic alcohol or by direct exposure to organic alcohol with powdered technical silicon in the presence of a catalyst (RU 2313485 C2, C01B 33/04, 07/10/2006). The disadvantage of this method is that it has a high fire hazard.

A known method of producing monosilane by the decomposition of magnesium silicide with mineral acids (RU 2357924 C2, C01B 33/04, 10.06.2008). The disadvantage of this method is that to obtain monosilane requires the synthesis of a new compound - alkaline earth metal silicide, which increases the number of stages in its preparation.

Recently, the technology for producing silicon and silicon metal compounds by fluoride methods from various types of silicon-containing raw materials has been widely developed. So, there is a known method for producing silanes by the interaction of silicon tetrafluoride with manganese hydride in a molten salt (US 4623531, СВВ 33/04, 11/18/1986). Also known is a method of producing monosilane, which consists in the interaction of calcium hydride with gaseous silicon tetrafluoride in a molten salt of lithium and potassium chlorides. Silicon tetrafluoride is used in a concentration of 50-100 vol.%. Silicon tetrafluoride is diluted with nitrogen purified from oxygen and introduced in excess of up to 2 wt.% With respect to stoichiometric. The resulting monosilane is subjected to further purification by adsorption. Granulated sodium fluoride is used as the sorbent. Cleaning is carried out in two stages: at 130-140 ° С and at 250-280 ° С (RU 2077483 Cl, СВВ 33/04, 04/20/1997). The technology is multi-stage, requires additional costs, which increases the cost of the target product.

Closest to the proposed in relation to the device and method for producing silicon compounds is the installation for producing a silicon compound - monosilane, and the production method implemented using this installation (RU 2164218 Cl, C01B 33/04, 03.20.2001). The installation comprises a housing, a reaction chamber, a gas distribution device, nozzles for supplying a gaseous component and outputting the target product, heating means, loading and unloading nozzles for the solid component, and a device for tilting the reaction chamber. The method includes heating the reaction chamber to operating temperature, supplying a solid component of lithium hydride, supplying a gaseous component of silicon tetrachloride, and withdrawing reaction products of monosilane and lithium chloride from the reactor. The known technical solution is based on the use of harmful chloride compounds, which makes the process environmentally unsafe, there is no stability in the yield of the obtained target product. In addition, it is impossible to obtain silicon compounds other than monosilane in a known installation.

According to traditional technology, high-purity silicon is obtained by complex chemical transformations of the original, the so-called metallurgical silicon, which is obtained by high-temperature reduction of quartzite - SiO ₂ carbon. The purity of the obtained silicon is about 95%. To increase the purity of silicon, silicon gas compounds are formed, which are subjected to deep purification and reduced in a special reactor with hydrogen at a temperature of 1100 ° C. The process is energy-consuming and complex, which significantly increases the cost of the final product.

A known method of obtaining crystalline powdered silicon from a silicon-containing compound, preferably silane, by synthesis in a plasma formed by applying energy from an electromagnetic source, the resulting reaction mixture is cooled and the reaction products are separated from gaseous substances in the form of a powder (RU 2340551 C2, C01B 33/02, 10.12 .2008). The disadvantage of this method is that the reaction cannot proceed with 100% yield of the final product. In addition, the implementation of the technology requires sophisticated equipment, which is not economically viable.

A known method of producing polycrystalline silicon, which involves obtaining an organically soluble salt by reacting hydrofluoric acid with an organic base, which is dried with an inert gas, is obtained by decomposition of this salt, silicon tetrafluoride and hydrogen fluoride are passed through silicon dioxide without separation and reduced with magnesium vapor in a vortex reactor at a temperature not exceeding 1000 ° C (RU 2358906 C2, C01B 33/033, 06/27/2007).

Passing the gas mixture through silicon dioxide leads to the formation of silicon and water, which must be removed from the reaction zone, which leads to the complexity and cost of the method.

A device for producing silicon is known, comprising an extraction unit connected by a piping system, a unit for drying the obtained extract, an extract decomposing unit to form gaseous silicon tetrafluoride and hydrogen fluoride, a condenser, a hydrogen fluoride neutralization unit to form silicon tetrafluoride, a magnesium evaporator, a silicon synthesis reactor, a separation unit for the resulting mixture of silicon and magnesium fluoride (WO 2009/005412 A2, C01B 33/033, 01/08/2009). A method for producing polycrystalline silicon from a solution of hydrofluoric acid is disclosed therein, including the interaction of hydrofluoric acid with an organic base to produce an organosoluble salt of hydrofluoric acid, which is dried with air or an inert gas at a temperature of 55-60 ° C, decomposition of the salt to produce a mixture of gaseous silicon tetrafluoride and fluoride hydrogen, which is passed through silicon dioxide in the presence of oleum, the recovery of the obtained gaseous tetraph Oridi silicon magnesium vapor and separating the silicon from magnesium fluoride. The specified source was adopted as the closest analogue. The resulting silicon does not have a sufficiently high degree of purity and stability of yield of the finished product. In addition, the process takes place without separation of the gas mixture resulting from the decomposition of hydrofluoric acid, which does not allow to obtain other silicon compounds in a known installation.

The problem to which the present invention is directed, is to create a line and method that allows to obtain high-purity silicon and its compounds without any additional means in a single cycle.

The technical result of the invention is the expansion of technological capabilities due to the possibility of obtaining in one line both silicon and its compounds with carbon, nitrogen, oxygen or hydrogen, increasing the yield stability of the finished product of high purity, increasing the environmental friendliness of the process, reducing energy costs through the use of low-temperature reactions.

The technical result is achieved by creating a line for producing silicon compounds, which contains a unit for the production of hydrofluoric acid, an extraction unit with an absorption column for trapping silicon tetrafluoride and hydrogen fluoride and a condenser for separating silicon tetrafluoride and hydrogen fluoride, a gas and gas station for gas storage and transportation, and a unit synthesis of silicon compounds, including a system for supplying gases to the reactor, and a reactor, the upper part of which is installed in a resistance furnace It is necessary to form a heating zone, and the lower one is connected to a receiving hopper for collecting synthesized particles in a removable container, a filter installed in the upper part of the hopper for gas outlet from it and directing it to the absorption column, the lower part of the reactor and the outer upper part of the hopper water and air cooling system.

To obtain silicon hydride compounds, the device may further comprise a magnesium evaporator connected by a channel to the reactor heating zone

To obtain polycrystalline silicon powder, the above line contains a gas-balloon station for storing and transporting monosilane and reaction gas and a monosilane decomposition unit, including a reactor, the upper part of which is installed in a resistance furnace to form a heating zone, and the lower one is connected to a receiving hopper for collecting synthesized particles in a removable container connected to it through a ball valve, a filter installed in the upper part of the hopper to absorb gas through it and direct it in a single column, the lower part of the reactor and the upper upper part of the hopper equipped with water and air cooling systems.

The technical result is also achieved by the method of producing silicon compounds, which is carried out on the proposed line and includes extraction of hydrofluoric acid with amine solutions in an inert diluent, decomposition of hydrofluoric acid extract with the formation of a mixture of silicon tetrafluoride and hydrogen fluoride gases, separation of silicon tetrafluoride and hydrogen fluoride by cooling the gas mixture flow with the formation of condensate of anhydrous hydrogen fluoride and gaseous silicon tetrafluoride and si synthesis of silicon compounds by feeding gaseous silicon tetrafluoride and reaction gas to the reactor. Moreover, for the synthesis of monosilane, hydrogen or anhydrous hydrogen fluoride and magnesium vapor are fed into the reactor as reaction gas, while magnesium vapor is supplied from a vacuum evaporator; for the synthesis of silicon carbide, a saturated hydrocarbon or a mixture of saturated hydrocarbons, in particular natural gas, is fed into the reactor as a reaction gas; for the synthesis of silicon nitride, a chemical compound of nitrogen with hydrogen, in particular gaseous ammonia, is fed into the reactor as a reaction gas; for the synthesis of silicon carbonitride, a saturated hydrocarbon or a mixture of saturated hydrocarbons, in particular a mixture of natural gas, and gaseous ammonia or gaseous amine is fed into the reactor as a reaction gas; for the synthesis of silicon dioxide, water vapor is supplied to the reactor as a reaction gas, and an alloying element is introduced into the reactor to produce silicon dioxide to change the refractive index of silicon dioxide.

As hydrofluoric acid, it is possible to use hydrofluoric acid, previously obtained by dissolving quartzite in hydrofluoric acid, or obtained by processing apatite, or obtained by processing feldspar, or obtained by etching glass.

An extract of hydrofluoric acid can be obtained by purification of hydrofluoric acid with solutions of an aliphatic amine in a diluent and drying with air at a temperature of 55-60 ° C. The decomposition of hydrofluoric acid extract can be carried out by treatment with a weak solution of oleum, and the organic phase formed during processing is washed and returned to the subsequent extraction of hydrofluoric acid.

Particles of polycrystalline silicon are obtained by feeding the obtained monosilane to the decomposition reactor of monosilane and its decomposition at a temperature of 600-700 ° C. Moreover, during the decomposition of monosilane into the reactor, it is possible to additionally introduce a chemical compound containing an alloying element that changes the type of silicon conductivity.

The monosilane obtained after synthesis can also be fed into the second reactor together with the reaction gas to obtain silicon compounds selected from the group: silicon carbide, silicon nitride, silicon carbonitride, silicon dioxide. In order to obtain silicon carbide, a saturated hydrocarbon or a mixture of saturated hydrocarbons, in particular natural gas, is supplied as a reaction gas together with monosilane; to obtain silicon nitride, a chemical compound of nitrogen with hydrogen, in particular gaseous ammonia, is supplied as a reaction gas together with monosilane; to obtain silicon carbonitride as a reaction gas, a saturated hydrocarbon or a mixture of saturated hydrocarbons, in particular natural gas, and ammonia gas or amine gas are fed together with monosilane; to obtain silicon dioxide, water vapor is supplied as a reaction gas together with monosilane; it is possible to introduce into the reactor together with water vapor a chemical compound containing an alloying element that changes the refractive index of silicon dioxide.

The invention consists in the following.

Figure 1 presents a schematic diagram of a line for producing metallic silicon and its compounds.

Figure 2 presents a schematic diagram of a unit for the synthesis of silicon compounds.

The line for producing metallic silicon and its compounds (Fig. 1) contains an assembly for producing hydrofluoric acid (6) arranged in series and combined into a single technological chain, connected by transport pipelines and a control system, and an extraction unit (5) containing an absorption column (1 ) for trapping silicon tetrafluoride, a condenser (2) for separating silicon tetrafluoride and hydrogen fluoride, a gas station (3) for pumping silicon tetrafluoride into a transport cylinder, system gas supply (4), which is a cabinet in which cylinders with silicon tetrafluoride and reaction gas are installed, equipped with a gas flow control system, a silicon compound synthesis unit (10), shown in FIG. 2 and containing a reactor (7), the upper part which is installed in a resistance furnace (12) to form a heating zone (13), and the lower part is connected to a hopper (18) for collecting particles in a removable container (17) through ball valves (16), and a gas supply system (4) to the reactor . To obtain monosilane, the reactor contains a magnesium evaporator (11) connected by a channel to the heating zone (13) of the reactor (7). The lower part of the reactor and the upper part of the hopper have a cooling system (14). The exhaust gas from the receiving hopper (18) through the filter (15) enters the heat exchanger trap (19), and then into the scrubber (20), from where the purified gas is supplied either to the gas station (8) or to the extraction condenser (2) block (5). To obtain metallic silicon, the line contains a second gas station (8) for injecting monosilane or hydrogen into a transport cylinder, which differs from the first by the presence of a gas supply system (4 ') instead of a gas liquefaction unit, a gas compression unit (4'), arranged similarly to a gas supply system (4) and a monosilane decomposition unit (9), including a second reactor 7 ', the upper part of which is installed in a resistance furnace to form a heating zone, and the lower one is connected to a hopper for collecting synthesized particles in a removable container, which It is one with the hopper through a filter to remove gas through it and direct it into the absorption column. The outer upper part of the hopper and the lower part of the reactor have a water and air cooling system for the formation of solid silicon particles.

The device works, and the method is as follows.

In node (6), hydrofluoric acid (CPA) is obtained by dissolving quartzite in hydrofluoric acid by the reaction:

SiO ₂ + 4HF = 2H ₂ O + SiF ₄ .

The gaseous silicon tetrafluoride formed during the reaction is absorbed by hydrofluoric acid to form CPA by the reaction:

SiF ₄ + 2HF = H ₂ SiF ₆ .

Dissolution is carried out in the mode of circulation of an aqueous solution.

You can use hydrofluoric acid obtained as a by-product in the processing of apatite:

Ca ₅ P (PO ₄ ) ₃ + 5H ₂ SO ₄ + 10H ₂ O = 3H ₃ PO ₄ + 5CaSO ₄ · 2H ₂ O + HF, where CPK is obtained in the presence of quartzites:

6HF + SiO ₂ = H ₂ SiF ₆ + 2H ₂ O.

You can use CPK, formed when hydrofluoric acid is obtained from feldspar:

CaF ₂ + 5H ₂ SO ₄ + 2H ₂ O = CaSO ₄ · 2H ₂ O + 2HF, as well as glass etching.

Regardless of the method for producing CPK, it enters the extraction unit (5) for the extraction cleaning operation.

The extraction unit is designed to extract hydrofluoric acid (CPA) with solutions of an aliphatic amine in a diluent. The extraction of CPK from an aqueous solution occurs by the reaction:

H ₂ SiF _{6 (water)} + Amin _(org) = H ₂ SiF ₆ · Amin _(org) .

At the same time, only CPK passes into the organic solution (extract), and the impurities remain in the aqueous solution. The extract is dried with air, heated to 50 ÷ 55 ° C, to remove moisture. The dry extract is treated with a weak solution of oleum. When this occurs, the decomposition of the KFK extract by the reaction:

H ₂ SiF ₆ · Amin _(org) + H ₂ SO _{4 (water)} = H ₂ SO ₄ · Amin _(org) + SiF _{4 (gas)} + 2HF _(gas) .

The resulting gas (a mixture of silicon tetrafluoride and hydrogen fluoride) is separated from the aqueous-organic mixture. The organic phase is washed from sulfuric acid with aqueous ammonia and returned to the extraction cycle.

CPK can be extracted by extraction from aqueous solutions of alkali metal silicofluorides (fluoride dumps). In this case, silicon tetrafluoride is extracted in the presence of equimolar amounts of hydrofluoric acid by the reaction:

H ₂ SiF _{6 (water)} + 2HF _(water) + Amin _(org) = 2NaF _(water) + H ₂ SiF ₆ · Amin _(org)

The sodium fluoride solution is disposed of by precipitation of artificial feldspar (CaF ₂ ), which can be returned to the production cycle:

2NaF + Ca (OH) ₂ = CaF ₂ + 2NaOH.

The resulting gas stream of a mixture of silicon tetrafluoride and hydrogen fluoride enters the condenser (2) and is additionally captured in the absorption column (1), in which the reaction gives an aqueous solution of hydrofluoric acid (CPA).

In the condenser (2), silicon tetrafluoride and hydrogen fluoride are separated by cooling the gas stream to a temperature of about + 10 ° C. At this temperature, anhydrous hydrogen fluoride condenses, while silicon tetrafluoride remains in the gas stream and is sent to the gas station (3). The station is designed to equip cylinders with a capacity of 5 to 40 liters for the purpose of storage and transportation of process gases between separate operations. Air is pre-pumped from the system, gas is condensed by cooling it to the temperature of liquid nitrogen. The resulting condensate is heated, resulting in its evaporation, and the resulting process gas is pumped into the transport tank to the required pressure.

For the synthesis of silicon compounds, gaseous silicon tetrafluoride from a gas station is fed into a reactor (7). To obtain a variety of silicon compounds with carbon, nitrogen, oxygen, and hydrogen, the silicon compound synthesis unit contains a gas supply system (4), from which the required process gas is supplied together with silicon tetrafluoride.

For the synthesis of silicon carbide carried out by the reactions:

SiF ₄ + CH ₄ = SiC + 4HF

SiF ₄ + 2CH ₄ = SiC ₂ + 4HF + 2H _2.

natural gas is supplied to the reactor (7). The exhaust gas is sent to a condenser (2), where it is cooled to a temperature of + 10 ° C to separate hydrogen fluoride. Synthesized silicon carbide is collected in a receiving container. By controlling the natural gas content of methane and silicon tetrafluoride in the reaction mixture, silicon carbides of non-stoichiometric composition can be obtained.

For the synthesis of silicon nitride from the gas supply system (4), gaseous ammonia and silicon tetrafluoride are fed into the reactor (7), the technological operations are similar to the synthesis of silicon carbide, the synthesis is carried out by the reaction:

3SiF ₄ + 4NH ₃ = Si ₃ N ₄ + 12HF.

A mixture of natural gas and ammonia gas is used to produce silicon carbonitride particles. The synthesis of silicon carbonitride is carried out by the reaction:

4S _i F ₄ + CH ₄ + 4NH ₃ = Si ₄ CN ₄ + 16HF.

Technological operations are similar to the synthesis of silicon carbide.

When water vapor is supplied to the reactor (7), silicon dioxide particles are synthesized by the reaction:

S _i F ₄ + 2H ₂ O = SiO ₂ + 4HF.

Technological operations are similar to the synthesis of silicon carbide.

To obtain silicon compounds with hydrogen, in particular monosilane (SiH ₄ ), the reactor (7) further comprises a magnesium evaporator. Magnesium in the form of lumpy material is loaded into a crucible, melted and cooled to solidify with the formation of a monolithic mass. Hydrogen or anhydrous hydrogen fluoride is fed into the reaction zone; monosilane synthesis is carried out by the reactions:

SiF ₄ + 2Mg + 2H ₂ = SiH ₄ + 2MgF ₂

SiF ₄ + 4Mg + 4HF = SiH ₄ + 4MgF ₂ .

The resulting solid magnesium fluoride is collected in a receiver container, and monosilane is removed from the reaction zone through a filter located in the lid of the receiving hopper to a gas station (8). Filling is as follows. Air is pre-pumped out of the system and compressed by an oil-free compressor. The gas can be compressed in stages. The first stage is compression to 0.25 MPa with a chemically resistant diaphragm pump, which fills the receiver. The second stage is compression to 4-15 MPa with a membrane compressor while filling the transport cylinder to the required pressure.

To obtain polycrystalline silicon powder, monosilane from the gas supply unit (4 ') is sent to the reactor (7'), where it is decomposed at a temperature of 600-700 ° C by the reaction:

SiH ₄ = Si + 2H ₂ . (one)

The process is carried out in an apparatus similar in design to the reactor (7) for the synthesis of silicon compounds. The difference is the absence of a magnesium vaporizer.

Upon receipt of metallic silicon, it is possible to dope it with various elements in order to create donor conductivity (volatile compounds of elements of the 5th group, phosphorus, arsenic, antimony, bismuth) or acceptor conductivity (volatile compounds of elements of the 3rd group, boron, aluminum, gallium, indium ) For example, in the case of doping with boron, borane is fed into the reactor simultaneously with monosilane in an amount that provides the required boron content in the silicon metal. In this case, the reaction proceeds simultaneously with reaction (1):

2ВН ₃ = 2В + 3Н ₂ , (2)

providing obtaining compounds Si-B with the desired content of boron.

The use of the reactor (9) is not limited to the production of silicon metal. Using the gas supply system in it as well as in the reactor (7), it is possible to obtain particles of silicon compounds. In this case, natural gas is supplied to the reactor (7 ') from the gas supply system (4'), and the synthesis of silicon carbide is carried out by the reactions:

SiH ₄ + CH ₄ = SiC + 4H ₂

SiF ₄ + 2CH ₄ = SiC ₂ + 6H ₂ .

The off-gas is compressed and sent to the monosilane synthesis operation. Synthesized silicon carbide particles are collected in a receiver container.

The synthesis of silicon nitride is carried out by the reaction:

3SiH ₄ + 4NH ₃ = Si ₃ N ₄ + 12H ₂ .

Technological operations are similar to the synthesis of silicon carbide, only in this case, instead of natural gas, gaseous ammonia is used.

The synthesis of silicon carbonitride is carried out by the reaction:

4SiH ₄ + CH ₄ + 4NH ₃ = Si ₃ CN ₄ + 16H ₂ .

Technological operations are similar to the synthesis of silicon carbide, only in this case a mixture of natural gas and gaseous ammonia is used.

The synthesis of silicon dioxide (quartz) is carried out by the reactions:

SiH ₄ + 2H ₂ O = SiO ₂ + 4H ₂

SiH ₄ + 2CO = SiO ₂ + CH ₄ + H ₂ .

Technological operations are similar to the synthesis of silicon carbide, only in this case, instead of natural gas, sharp water vapor is supplied to the reactor.

To change the refractive index of synthetic quartz during production, it can be doped with volatile compounds of germanium, phosphorus, titanium, antimony aluminum (to increase the refractive index) or boron (to decrease the refractive index) according to reactions similar to reaction (2).

Examples of carrying out the invention.

Example 1

100 g of quartzite were loaded into the apparatus for producing CPK (6) and 1 l of a solution of 10 mol / l of hydrofluoric acid was poured. In the apparatus, heating was turned on. Upon reaching a temperature of 60 ° C, cooling of the absorption column of the apparatus was turned on. In this case, intensive mixing of the suspension took place. The time of complete dissolution of quartzite was 7-10 minutes. The resulting solution contained 19-21% by weight. KFK.

The purification of hydrofluoric acid (CPA) was carried out in the extraction unit (5). The initial 20% acid solution was fed to the 8th stage of the EC-33 centrifugal extractor block (5). The extractant — a 30% solution of trialkylamine in triethylbenzene — was fed into the first stage of the block. The ratio of the flows of the organic and aqueous phases (O: B) was 6.7: 1. A washing solution containing 2 mol / L hydrofluoric acid was supplied to the 10th stage of the extraction block at O: B = 10: 1. The extract emerging from the 10th stage was dried with purified air at a temperature of 50 ± 5 ° C. The dry extract was treated in a packed column with a 5% oleum solution at O: B = 1: 0.06. The evolved gas was absorbed in the absorption column with distilled water at a gas: water ratio of 120: 1. The extract after removal of CPK from it was sequentially treated with distilled water (O: B = 2.25: 1, 11-12 steps) and an aqueous solution of 2 mol / L ammonia (O: B = 4: 1, 13-15 steps). The extractant was saturated with 10 mol / L hydrofluoric acid in a column (0: B = 50: 1) and returned to the extraction cycle. The recovery of CPK in the purification cycle was 99.95%.

The content of impurities in the initial and purified CPK is presented in

table 1.

Table 1. The content of impurities in the original and purified CPK,% weight. (in terms of silicon).

Impurity Fe Na Mg Sa R Source CPK 0.1 0.06 0.09 0.02 0.08 Purified KFK 5 · 10 ^-6 2 · 10 ^-5 2 · 10 ^-5 1 · 10 ^-5 4 · 10 ^-6

The gas released during the treatment of the CPK extract with oleum in the column was directed to a condenser (2), where it was cooled to a temperature of + 10 ° С. Anhydrous liquid hydrogen fluoride was removed from the lower part of the condenser, the gas fraction was sent to a 10-liter cylinder of a gas-balloon station (3), cooled with liquid nitrogen. After filling the cylinder by ¼ of the volume, the gas supply was stopped and liquid nitrogen was drained through the cryogenic valve. The gas evolved when the cylinder was heated to room temperature was pumped into a transport cylinder of a gas cylinder station (3) with a capacity of 40 liters. The final gas pressure in the 40-liter cylinder was 18-21 atm.

The silicon content of anhydrous hydrogen fluoride was 2 · 10 ^-3 % by weight. The content of hydrogen fluoride in the cylinder with silicon tetrafluoride was less than 0.01% by weight.

Monosilane was synthesized in a silicon compound synthesis unit containing a reactor (7). 25 g of magnesium metal were loaded into a steel crucible St3. The crucible was placed in a magnesium evaporator, which was heated to a temperature of 650 ° C. Hydrogen with a flow rate of 400 ml / h or gaseous hydrogen fluoride with a flow rate of 800 ml / h was supplied to the magnesium evaporator, which transported the formed magnesium vapor into the reactor (7). At the same time, silicon tetrafluoride was supplied to the reactor from the gas supply system (4) at a flow rate of 200 ml / h. The reaction was carried out for 1 hour.

The resulting mixture was cooled in the lower zone of the reactor and the receiving hopper. Gas was removed from the hopper through a filter and sent to a packed absorption column filled with 10% aqueous sodium hydroxide solution. The volume of the absorption solution was 0.5 L. A solid precipitate of magnesium fluoride after termination of the reaction (gas supply shutdown) was discharged from the hopper into a removable container with open ball valves.

The completeness of the synthesis reaction was judged by the concentrations of silicon and fluoride ion in the absorption solution.

The direct yield of monosilane in the synthesis reaction was stably 99.5%.

Example 2

Sodium silicofluoride was purified in the extraction unit (5).

The initial solution containing 6 g / l sodium cremofluoride and 1.3 g / l hydrofluoric acid was fed to the 8th step of the EC-33 centrifugal extractor block (5). The extractant — a 30% solution of trialkylamine in triethylbenzene — was fed into the first stage of the block. The ratio of the flows of organic and aqueous phases (O: B) was 1.5: 1. A washing solution containing 2 mol / L hydrofluoric acid was supplied to the 10th stage of the extraction block at O: B = 10: 1. The extract emerging from the 10th stage was dried with purified air at a temperature of 50 ± 5 ° C. The dry extract was treated in a packed column with a 5% oleum solution at O: B = 1: 0.06. The evolved gas was absorbed in the absorption column with distilled water at a gas: water ratio of 120: 1. The extract after removal of hydrofluoric acid (CPA) from it was successively treated with distilled water (O: B = 2.25: 1, 11-12 stages) and an aqueous solution of 2 mol / L ammonia (O: B = 4: 1, 13-15 steps). The extractant was saturated with 10 mol / L hydrofluoric acid in a column (O: B = 50: 1) and returned to the extraction cycle. The recovery of sodium silicofluoride in the purification cycle was 99.92%.

The content of impurities in the initial sodium silicofluoride and purified CPK are presented in table 2.

Table 2. The content of impurities in the initial sodium silicofluoride and purified CPK,% weight. (in terms of silicon).

Impurity Fe Na Mg Ca R Starting sodium silicofluoride 0.21 62.18 0.11 0.24 0,03 Purified KFK 7 · 10 ^-6 5 · 10 ^-5 3 · 10 ^-5 2 · 10 ^-5 2 · 10 ^-6

Silicon tetrafluoride from purified CPA was obtained analogously to example 1.

The synthesis of silicon carbide was carried out in a block for the synthesis of silicon compounds containing a reactor (7). The reactor was preheated to a temperature of 350 ° C. From the gas supply system (4) of the silicon compound synthesis unit, methane and silicon tetrafluoride were supplied to the reactor (7) at a rate of 400 ml / hour each for 1 hour.

The resulting mixture was cooled in the lower zone of the reactor and the receiving hopper using a water and air cooling system. Gas was removed from the hopper through a filter and sent to a condenser (2), cooled by a cryostat to a temperature of + 5 ± 2 ° С. The resulting condensate of anhydrous hydrogen fluoride accumulated in the lower part of the apparatus. The gas, after the condenser, was sent to a packed absorption column filled with a 10% aqueous sodium hydroxide solution. The volume of the absorption solution was 0.5 L. A solid precipitate of silicon carbide after termination of the reaction (gas supply shutdown) was discharged from the hopper into a removable container with open ball valves.

The completeness of the synthesis reaction was judged by the concentrations of silicon and fluoride ion in the absorption solution.

The direct yield of silicon carbide by the synthesis reaction was stably 98.6% ± 0.015%.

The silicon content of anhydrous hydrogen fluoride was less than 10 ^-3 % by weight.

The carbon content of the discharged silicon carbide was 30%.

Example 3

The synthesis of non-stoichiometric silicon carbide was carried out under the conditions of example 2. The consumption of silicon tetrafluoride was 400 ml / h, the methane consumption was 600 ml / h. The reaction temperature was maintained at 750 ° C.

The direct yield of silicon carbide by the synthesis reaction was stably 97.3% ± 0.01%.

The silicon content of anhydrous hydrogen fluoride was less than 10 ^-3 % by weight.

The carbon content of the discharged silicon carbide was 39%.

Example 4

Silicon tetrafluoride was obtained analogously to example 1.

The synthesis of silicon nitride was carried out in a reactor (7), which was preheated to a temperature of 350 ° C. Silicon tetrafluoride with a flow rate of 400 ml / h and ammonia with a flow rate of 300 ml / h were fed into the reactor from the gas supply system (4), the reaction was carried out for 1 hour. All other operations were carried out under the conditions of example 2.

The direct yield of silicon nitride in the synthesis reaction was stably 98.9% ± 0.01%.

The silicon content of anhydrous hydrogen fluoride was less than 10 ^-3 % by weight.

The nitrogen content of the discharged silicon nitride was 40%.

Example 5

Silicon tetrafluoride was obtained analogously to example 1. Synthesis of silicon carbonitride was carried out in the reactor (7), preheated to a temperature of 350 ° C. Silicon tetrafluoride with a flow rate of 400 ml / h, methane with a flow rate of 100 ml / h and ammonia with a flow rate of 400 ml / h were fed into the reactor from a gas supply system (4). The reaction was carried out for 1 hour. All other operations were carried out under the conditions of example 2.

The direct yield of silicon carbonitride by the synthesis reaction was stably 99.8% ± 0.03%.

The silicon content of anhydrous hydrogen fluoride was less than 10 ^-3 % by weight.

The nitrogen content of the discharged silicon carbonitride was 31%. The carbon content of the discharged silicon carbonitride was 6.7%.

Example 6

Silicon tetrafluoride was obtained analogously to example 1.

Quartzite was synthesized in a reactor (7). The reactor was preheated to a temperature of 650 ° C. Silicon tetrafluoride with a flow rate of 400 ml / h was supplied from the gas supply system (4) to the reactor; at the same time, water vapor obtained from the steam generator of the gas supply system (4) was supplied to the reactor with a flow rate of 800 ml / hour. The reaction was carried out for 1 hour. All other operations were carried out under the conditions of example 2.

The direct yield of quartzite by the synthesis reaction was stably 99.4% ± 0.015%.

The silicon content of anhydrous hydrogen fluoride was less than 10 ^-3 % by weight.

The oxygen content in the discharged quartzite was 53%.

Example 7

Monosilane was obtained according to example 1.

The decomposition of monosilane to obtain metallic silicon was carried out in the decomposition unit reactor (9). Monosilane with a flow rate of 400 ml / h was supplied from the gas supply system (4 ') to the reactor (7'), preheated to a temperature of 750 ° C. The reaction was carried out for 1 hour.

The resulting mixture was cooled in the lower zone of the reactor and the receiving hopper using a water and air cooling system. Gas was removed from the hopper through a filter and sent to a packed absorption column filled with 10% aqueous sodium hydroxide solution. The volume of the absorption solution was 0.5 L. The gas after the absorption column was directed to the receiver. As gas accumulated in the receiver, it was pumped by a membrane compressor into the transport cylinder of the gas station (8).

A solid precipitate of metallic silicon after termination of the reaction (gas supply shutdown) was discharged from the hopper into a removable container with open ball valves.

The completeness of the synthesis reaction was judged by the concentration of silicon in the absorption solution.

The direct yield of silicon metal through the decomposition reaction was stably 99.95 ± 0.01%.

The impurity content in metallic silicon was less than 10 ^-6 % by weight.

Example 8

The production of silicon metal doped with boron was carried out in the reactor (7 ') of the monosilane decomposition unit according to the technology and modes corresponding to Example 7. The difference is that simultaneously with monosilane, borane is fed into the reactor (7') at a flow rate of 4 ml / hour.

The direct yield of doped metallic silicon by the decomposition reaction was stably 99.95 ± 0.01%.

The boron content in metallic silicon was 6%.

The content of the remaining impurities in metallic silicon was less than 10 ^-3 % by weight.

Example 9

The synthesis of silicon dicarbide was carried out under the conditions of example 7. The flow rate of monosilane was 400 ml / hour, the flow rate of methane was 800 ml / hour.

The direct yield of silicon dicarbide by the synthesis reaction was stably 99.3 ± 0.02%.

The carbon content of the discharged silicon carbide was 46%.

Example 10

The synthesis of silicon nitride was carried out in a reactor (7 '). Monosilane with a flow rate of 400 ml / h and ammonia with a flow rate of 300 ml / h were fed into the reactor (7 ') from the gas supply system (4'). The reactor was preheated to a temperature of 350 ° C. The reaction was carried out for 1 hour. All other operations were carried out under the conditions of example 7.

The direct yield of silicon nitride by the synthesis reaction was stably 99.8 ± 0.015%.

The nitrogen content of the discharged silicon nitride was 40%.

Example 11

The synthesis of silicon carbonitride was carried out analogously to example 10, except that simultaneously with monosilane, methane with a flow rate of 100 ml / h and ammonia with a flow rate of 400 ml / h were fed into the reactor (7 ') from the gas supply system.

The direct yield of silicon carbonitride by the synthesis reaction was stably 99.6 ± 0.01%.

The nitrogen content of the discharged silicon carbonitride was 31%.

The carbon content of the discharged silicon carbonitride was 6.7%.

Example 12

The synthesis of quartzite was carried out in a reactor (7 '). Silicon tetrafluoride with a flow rate of 400 ml / hour was fed into the reactor (7 '), preheated to a temperature of 650 ° C. At the same time, 800 ml / h of water was received at a flow rate from the steam generator. The reaction was carried out for 1 hour. All other operations were carried out under the conditions of example 7.

The direct yield of quartzite by the synthesis reaction was stably 99.4 ± 0.01%.

The oxygen content in the discharged quartzite was 53%.

From the above examples it follows that a universal installation is proposed, on which, without changing its configuration, it is possible to obtain various silicon compounds: carbides, nitrides, carbonitrides, oxides, hydrides. In addition, when using an additional monosilane decomposition reactor at the proposed installation, it is possible to obtain pure silicon metal, as well as its compounds using monosilane decomposition. The resulting target products have a high degree of purity and a stable yield. The method carried out on the proposed installation is environmentally friendly, since there is no use of harmful chloride compounds, and the process of obtaining the target product is carried out in a single cycle. The reactions used to obtain the target product take place at low temperatures, which significantly reduces the energy consumption for their implementation.

Claims (30)

1. A line for producing silicon compounds, containing a unit for producing hydrofluoric acid, an extraction unit with an absorption column for collecting silicon tetrafluoride and hydrogen fluoride and a capacitor for separating silicon tetrafluoride and hydrogen fluoride, a gas and gas storage station for transporting gases, and a silicon compound synthesis unit, including a gas supply system to the reactor, and a reactor, the upper part of which is installed in a resistance furnace to form a heating zone, and the lower is connected to a receiving hopper for collecting the synthesized particles into a removable container, a filter installed in the upper part of the hopper, for discharging gas from it and directing it to the absorption column, the lower part of the reactor and the outer upper part of the hopper equipped with a water and air cooling system. 2. The line according to claim 1, characterized in that to obtain monosilane it further comprises a magnesium evaporator connected by a channel to the heating zone of the reactor. 3. A line for producing polycrystalline silicon powder, comprising a line for producing monosilane according to claim 2, a gas station for storing and transporting monosilane and reaction gas, and a monosilane decomposition unit, including a reactor, the upper part of which is installed in a resistance furnace to form a heating zone, and the lower one is connected to a receiving hopper for collecting synthesized particles into a removable container connected to it through a ball valve, a filter installed in the upper part of the hopper to discharge gas through it and The direction in its absorption column, the lower part of the reactor and the outer upper part of the hopper are provided with systems of water and air cooling. 4. A method of producing silicon compounds, including extraction of hydrofluoric acid with amine solutions in an inert diluent, decomposition of an extract of hydrofluoric acid with the formation of a gas mixture of silicon tetrafluoride and hydrogen fluoride, separation of silicon tetrafluoride and hydrogen fluoride by cooling the gas mixture to form anhydrous hydrogen fluoride and gaseous condensate silicon tetrafluoride and the synthesis of silicon compounds by feeding gaseous silicon tetrafluoride and p reaction gases from the range of hydrogen, anhydrous hydrogen fluoride and magnesium vapor, saturated hydrocarbon, a mixture of saturated hydrocarbons, a chemical compound of nitrogen with hydrogen, gaseous amine, water vapor. 5. The method according to claim 4, characterized in that for the synthesis of monosilane as a reaction gas, hydrogen or anhydrous hydrogen fluoride and magnesium vapor are fed into the reactor. 6. The method according to claim 5, characterized in that the vaporous magnesium is fed from a vacuum evaporator. 7. The method according to claim 4, characterized in that for the synthesis of silicon carbide as a reaction gas, a saturated hydrocarbon or a mixture of saturated hydrocarbons, in particular natural gas, is fed into the reactor. 8. The method according to claim 4, characterized in that for the synthesis of silicon nitride as a reaction gas, a chemical compound of nitrogen with hydrogen, in particular gaseous ammonia, is fed into the reactor. 9. The method according to claim 4, characterized in that for the synthesis of silicon carbonitride as a reaction gas, a saturated hydrocarbon or a mixture of saturated hydrocarbons, in particular natural gas, and gaseous ammonia or gaseous amine is fed into the reactor. 10. The method according to claim 4, characterized in that for the synthesis of silicon dioxide as a reaction gas, water vapor is supplied to the reactor. 11. The method according to claim 10, characterized in that the chemical compound containing an alloying element that changes the refractive index of silicon dioxide is additionally introduced into the reactor. 12. The method according to claim 4, characterized in that the use of hydrofluoric acid, previously obtained by dissolving quartzite in hydrofluoric acid. 13. The method according to claim 4, characterized in that the use of hydrofluoric acid obtained from the processing of apatite. 14. The method according to claim 4, characterized in that the use of hydrofluoric acid obtained by processing feldspar. 15. The method according to claim 4, characterized in that the use of hydrofluoric acid obtained by etching glass. 16. The method according to any one of claims 4-15, characterized in that the hydrofluoric acid extract is preliminarily obtained by purification of hydrofluoric acid with aliphatic amine solutions in a diluent and air drying at a temperature of 55-60 ° C. 17. The method according to any one of claims 4-15, characterized in that the hydrofluoric acid extract is preliminarily obtained by purification of the hydrofluoric acid salt, for example sodium silicofluoride, and hydrofluoric acid with solutions of an aliphatic amine in a diluent and drying with air at a temperature of 55-60 ° C. 18. The method according to any one of claims 4 to 15, characterized in that the decomposition of the hydrofluoric acid extract is carried out by treatment with a weak solution of oleum, the organic phase formed during processing is washed and returned to the subsequent extraction of hydrofluoric acid. 19. The method according to clause 16, characterized in that the decomposition of the extract of hydrofluoric acid is carried out by treatment with a weak solution of oleum, and the organic phase formed during processing is washed and returned to the subsequent extraction of hydrofluoric acid. 20. The method according to 17, characterized in that the decomposition of the extract of hydrofluoric acid is carried out by treatment with a weak solution of oleum, and the organic phase formed during processing is washed and returned to the subsequent extraction of hydrofluoric acid. 21. The method according to claim 5 or 6, characterized in that the monosilane obtained after synthesis is fed into the reactor for the decomposition of monosilane together with the reaction gas to obtain silicon compounds selected from the group: silicon carbide, silicon nitride, silicon carbonitride, silicon dioxide. 22. The method according to item 21, characterized in that to obtain silicon carbide as a reaction gas together with monosilane serves a saturated hydrocarbon or a mixture of saturated hydrocarbons, in particular natural gas. 23. The method according to item 21, characterized in that to obtain silicon nitride as a reaction gas, together with monosilane serves chemical compound of nitrogen with hydrogen, in particular gaseous ammonia. 24. The method according to item 21, characterized in that to obtain silicon carbonitride as a reaction gas together with monosilane serves a saturated hydrocarbon or a mixture of saturated hydrocarbons, in particular natural gas, and gaseous ammonia or gaseous amine. 25. The method according to item 21, wherein in order to obtain silicon dioxide as a reaction gas together with monosilane serves water vapor. 26. The method according A.25, characterized in that the reactor is additionally introduced a chemical compound containing an alloying element that changes the refractive index of silicon dioxide. 27. A method for producing polycrystalline silicon particles, comprising supplying monosilane to the reactor of a monosilane decomposition unit and decomposing it at a temperature of 600-700 ° C., characterized in that monosilane obtained by the method according to any one of claims 5-6 is fed into the reactor. 28. The method according to item 27, wherein the decomposition of monosilane in the reactor additionally enter a chemical compound containing an alloying element that changes the type of conductivity of silicon. 29. Polycrystalline silicon powder obtained by the method according to item 27 or 28. 30. Inorganic compound powder obtained by the method according to any one of claims 4 to 26.

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