CN116216723A - Co-production process of nano silicon and granular silicon - Google Patents
Co-production process of nano silicon and granular silicon Download PDFInfo
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- CN116216723A CN116216723A CN202310254990.0A CN202310254990A CN116216723A CN 116216723 A CN116216723 A CN 116216723A CN 202310254990 A CN202310254990 A CN 202310254990A CN 116216723 A CN116216723 A CN 116216723A
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- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 62
- 239000010703 silicon Substances 0.000 title claims abstract description 62
- 239000005543 nano-size silicon particle Substances 0.000 title claims abstract description 56
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 32
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 107
- 239000011863 silicon-based powder Substances 0.000 claims abstract description 44
- 239000007789 gas Substances 0.000 claims abstract description 33
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 claims abstract description 27
- 229910000077 silane Inorganic materials 0.000 claims abstract description 27
- 238000005984 hydrogenation reaction Methods 0.000 claims abstract description 24
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 21
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 19
- 238000007323 disproportionation reaction Methods 0.000 claims abstract description 18
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 claims abstract description 18
- ZDHXKXAHOVTTAH-UHFFFAOYSA-N trichlorosilane Chemical compound Cl[SiH](Cl)Cl ZDHXKXAHOVTTAH-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000005052 trichlorosilane Substances 0.000 claims abstract description 16
- VXEGSRKPIUDPQT-UHFFFAOYSA-N 4-[4-(4-methoxyphenyl)piperazin-1-yl]aniline Chemical compound C1=CC(OC)=CC=C1N1CCN(C=2C=CC(N)=CC=2)CC1 VXEGSRKPIUDPQT-UHFFFAOYSA-N 0.000 claims abstract description 14
- 238000003723 Smelting Methods 0.000 claims abstract description 14
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims abstract description 14
- 239000005049 silicon tetrachloride Substances 0.000 claims abstract description 14
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 12
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 10
- 238000002360 preparation method Methods 0.000 claims abstract description 9
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 7
- 238000001816 cooling Methods 0.000 claims abstract description 6
- 238000002156 mixing Methods 0.000 claims abstract description 6
- 238000006479 redox reaction Methods 0.000 claims abstract description 6
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 6
- 238000003801 milling Methods 0.000 claims abstract description 5
- 239000000654 additive Substances 0.000 claims abstract description 4
- 230000000996 additive effect Effects 0.000 claims abstract description 4
- 238000012216 screening Methods 0.000 claims abstract description 4
- 239000000203 mixture Substances 0.000 claims abstract description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 40
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 34
- 238000000034 method Methods 0.000 claims description 28
- 239000002245 particle Substances 0.000 claims description 21
- 230000008569 process Effects 0.000 claims description 20
- 239000010865 sewage Substances 0.000 claims description 18
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 17
- 239000003546 flue gas Substances 0.000 claims description 17
- 239000001257 hydrogen Substances 0.000 claims description 17
- 239000000047 product Substances 0.000 claims description 17
- 239000002912 waste gas Substances 0.000 claims description 17
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 14
- 229910000041 hydrogen chloride Inorganic materials 0.000 claims description 14
- 239000001301 oxygen Substances 0.000 claims description 14
- 229910052760 oxygen Inorganic materials 0.000 claims description 14
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 13
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 13
- 239000004571 lime Substances 0.000 claims description 13
- 239000002002 slurry Substances 0.000 claims description 13
- 239000002351 wastewater Substances 0.000 claims description 13
- 239000005046 Chlorosilane Substances 0.000 claims description 12
- KOPOQZFJUQMUML-UHFFFAOYSA-N chlorosilane Chemical compound Cl[SiH3] KOPOQZFJUQMUML-UHFFFAOYSA-N 0.000 claims description 12
- 239000008267 milk Substances 0.000 claims description 12
- 210000004080 milk Anatomy 0.000 claims description 12
- 235000013336 milk Nutrition 0.000 claims description 12
- 238000006243 chemical reaction Methods 0.000 claims description 11
- 238000004064 recycling Methods 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 10
- 239000002918 waste heat Substances 0.000 claims description 9
- 238000002386 leaching Methods 0.000 claims description 8
- 238000009835 boiling Methods 0.000 claims description 7
- 239000006227 byproduct Substances 0.000 claims description 7
- 239000002893 slag Substances 0.000 claims description 7
- 239000000428 dust Substances 0.000 claims description 6
- 238000000227 grinding Methods 0.000 claims description 6
- 229920006395 saturated elastomer Polymers 0.000 claims description 6
- 238000007873 sieving Methods 0.000 claims description 6
- 238000010612 desalination reaction Methods 0.000 claims description 4
- 238000006477 desulfuration reaction Methods 0.000 claims description 4
- 230000023556 desulfurization Effects 0.000 claims description 4
- 238000001035 drying Methods 0.000 claims description 4
- 150000003839 salts Chemical class 0.000 claims description 4
- 238000007906 compression Methods 0.000 claims description 3
- 230000006835 compression Effects 0.000 claims description 3
- 238000005530 etching Methods 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 238000001223 reverse osmosis Methods 0.000 claims description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 3
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 3
- 239000013589 supplement Substances 0.000 claims description 3
- 230000003311 flocculating effect Effects 0.000 claims 1
- 229910021487 silica fume Inorganic materials 0.000 claims 1
- 239000013078 crystal Substances 0.000 abstract description 5
- 238000000926 separation method Methods 0.000 abstract description 5
- XJKVPKYVPCWHFO-UHFFFAOYSA-N silicon;hydrate Chemical compound O.[Si] XJKVPKYVPCWHFO-UHFFFAOYSA-N 0.000 abstract description 5
- 239000002994 raw material Substances 0.000 description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 7
- MROCJMGDEKINLD-UHFFFAOYSA-N dichlorosilane Chemical compound Cl[SiH2]Cl MROCJMGDEKINLD-UHFFFAOYSA-N 0.000 description 4
- 239000003610 charcoal Substances 0.000 description 3
- 238000010276 construction Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 238000005345 coagulation Methods 0.000 description 2
- 230000015271 coagulation Effects 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 238000007865 diluting Methods 0.000 description 2
- 239000004744 fabric Substances 0.000 description 2
- 238000005189 flocculation Methods 0.000 description 2
- 230000016615 flocculation Effects 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 239000008235 industrial water Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 229920005591 polysilicon Polymers 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- 238000004062 sedimentation Methods 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910003902 SiCl 4 Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000004067 bulking agent Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- FDNAPBUWERUEDA-UHFFFAOYSA-N silicon tetrachloride Chemical compound Cl[Si](Cl)(Cl)Cl FDNAPBUWERUEDA-UHFFFAOYSA-N 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/02—Silicon
- C01B33/021—Preparation
- C01B33/023—Preparation by reduction of silica or free silica-containing material
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/02—Silicon
- C01B33/037—Purification
- C01B33/039—Purification by conversion of the silicon into a compound, optional purification of the compound, and reconversion into silicon
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
- Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Silicon Compounds (AREA)
Abstract
The invention discloses a co-production process of nano silicon and granular silicon, which comprises the steps of mixing silica, a reducing agent and an additive in proportion, adding the mixture into an ore-smelting electric furnace, carrying out oxidation-reduction reaction, and cooling nano silicon water produced by smelting at high temperature to prepare nano silicon blocks; the nano silicon blocks are sent into a milling workshop, and metallurgical grade silicon powder, high-precision polycrystalline silicon powder and fine silicon powder are obtained through screening separation after milling; the metallurgical grade silicon powder and the fine silicon powder are sold as products; feeding high-precision polycrystalline silicon powder, hydrogen and silicon tetrachloride into a circulating fluidized bed for hydrogenation reaction; the generated trichlorosilane is sent to a silane preparation device for disproportionation reaction; and (3) delivering silane gas generated by the disproportionation reaction into a fluidized bed reactor for homogeneous decomposition reaction, and carrying out aftertreatment after silicon is deposited on the surface of the seed crystal to obtain a granular silicon product.
Description
Technical Field
The invention belongs to the field of polysilicon production, and particularly relates to a co-production process of nano silicon and granular silicon.
Background
At present, the existing nano silicon projects are produced by independently building factories and independently building modules, raw material silica is subjected to washing, screening and drying, then the raw material silica and reducing agent charcoal are respectively proportioned according to different proportions, the proportions of the raw material and the reducing agent charcoal are controlled by a program, the raw material and the reducing agent charcoal are respectively gathered on a belt from a stock bin, the raw material and the belt are uniformly mixed by a mixing program, the raw material enter an electric furnace, after various materials are in place, current is led to an electrode, the materials in the furnace are heated, the temperature reaches to a high temperature of more than 1800 ℃, silicon is reduced in the furnace, the liquid state is presented, silicon water is discharged through a silicon outlet and cast into a silicon ingot, and the silicon ingot is crushed and packaged into nano silicon powder for sale; the high-temperature gas from the electric furnace is subjected to dust removal to recover fine silicon powder for sale, and desulfurization and denitrification and flue gas discharge are carried out.
The process flow is that hydrogen, industrial silicon powder and silicon tetrachloride are mixed according to a certain proportion and enter a cold hydrogenation circulating fluidized bed to produce trichlorosilane, dichlorosilane, unreacted silicon tetrachloride, hydrogen, fine silicon powder and other products through hydrogenation reaction, after the products are treated by a rectifying tower, dichlorosilane, trichlorosilane and silicon tetrachloride are respectively purified, the trichlorosilane enters a silane gas preparation process to produce dichlorosilane and silicon tetrachloride through disproportionation reaction, the dichlorosilane is produced into silane gas through disproportionation reaction, the silane gas is purified and enters a particle silicon process, more than 90% of silane gas and hydrogen are subjected to homogeneous decomposition reaction in the particle silicon fluidized bed, the silicon is decomposed and deposited on the surface of the crystal, the silicon is grown gradually, the purity of the formed particle silicon can reach more than 99.99999%, the finished product is discharged out of the fluidized bed, and the finished product is sold/packaged after the silicon chloride is treated and qualified.
Disclosure of Invention
The invention aims to: aiming at the defects of the prior art, the invention provides a co-production process of nano silicon and granular silicon, which fundamentally solves the transportation and waste of energy sources such as water sources, electric power, raw materials, manpower and the like.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a co-production process of nano silicon and granular silicon comprises the following steps:
(1) Mixing silica, a reducing agent and an additive in proportion, adding the mixture into an ore-smelting electric furnace, carrying out oxidation-reduction reaction under an oxygen atmosphere, and cooling nano silicon water produced by smelting at a high temperature to prepare nano silicon blocks;
(2) Feeding the nano silicon blocks obtained in the step (1) into a grinding workshop, grinding, and screening and separating to obtain metallurgical grade silicon powder, high-precision polycrystalline silicon powder and fine silicon powder nano silicon products; the nano silicon is a popular name of industrial silicon powder produced in the field, and does not refer to silicon powder with nano-scale particle size;
(3) The obtained metallurgical grade silicon powder and fine silicon powder are sold as products; feeding high-precision polycrystalline silicon powder, hydrogen and Silicon Tetrachloride (STC) into a circulating fluidized bed for hydrogenation reaction to produce Trichlorosilane (TCS);
(4) Sending Trichlorosilane (TCS) generated by the hydrogenation reaction in the step (3) to a silane preparation device for disproportionation reaction;
(5) Step (4) of disproportionating silane gas (SiH) 4 ) And (3) feeding the silicon into a fluidized bed reactor for homogeneous decomposition reaction, and carrying out aftertreatment after silicon is deposited on the surface of the seed crystal to obtain a granular silicon product.
Specifically, in the step (1), the reducing agent is, for example, clean coal, and the additive is, for example, a bulking agent.
In the step (2), the particles which are more than or equal to 600 mu m and are separated by sieving after grinding are metallurgical grade silicon powder; the residual particles with the particle size of 150-600 μm collected by the cyclone separator after sieving are high-precision polycrystalline silicon powder; the particles which are taken away by the cyclone separator gas and are less than or equal to 150 mu m are fine silicon powder, and the fine silicon powder is collected through a metal powder sintering membrane filter.
In the step (4), silicon Tetrachloride (STC) generated by the disproportionation reaction is returned to the circulating fluidized bed in the step (3) for recycling, and the hydrogenation reaction is carried out again; and the byproduct Trichlorosilane (TCS) generated by the disproportionation reaction is reentered into a silane preparation device for recycling.
Further, in the step (5), H generated by the homogeneous decomposition reaction 2 Returning to the step (3) for hydrogenation recycling.
Further, in the step (1), high-temperature flue gas generated by the submerged arc furnace enters a waste heat boiler to generate saturated steam, redundant high-temperature flue gas enters an air cooler, heat is exchanged to the atmosphere through heat exchange between outdoor air and the high-temperature flue gas in the air cooler, and the temperature of the flue gas is reduced; mixing the flue gas with the reduced temperature with the low-temperature flue gas after the waste heat boiler, and uniformly passing through a cloth bag dust remover; the micro silicon powder captured by the bag-type dust collector is collected and sold, and the collected flue gas is discharged after reaching the standard through desulfurization and denitrification treatment.
In the step (3), the high-boiling-point substances generated by the hydrogenation reaction are sent to a slurry treatment reaction kettle, and the high-boiling-point substances, hydrochloric acid and lime milk are mixed according to a certain proportion in the reaction kettle to treat the high-boiling-point substances in a harmless way; high-salt wastewater generated by slag slurry treatment is sent to sewage treatment;
the chlorosilane waste gas generated by hydrogenation is sent to a chlorosilane waste gas treatment leaching tower, lime milk is adopted for leaching, the lime milk and the chlorosilane waste gas in the leaching tower are contacted from top to bottom for reaction, and the generated high-salt waste water is sent to sewage treatment;
the recovered water produced by sewage treatment is used as water for preparing lime milk in slag slurry treatment and chlorosilane waste gas treatment, and industrial crystalline salt byproduct is produced.
Further, the silane waste gas generated by the disproportionation reaction in the step (4) and the silane waste gas generated by the homogeneous decomposition reaction in the step (5) are sent into a silane tail gas treatment device together, industrial water is used for diluting liquid alkali according to a proportion, then the silane tail gas is absorbed, and the generated waste water is sent to sewage treatment.
Further, resolving hydrogen chloride gas from concentrated hydrochloric acid through a hydrochloric acid resolving tower, demisting and drying the hydrogen chloride gas, adopting a compressor to compress the hydrogen chloride, sending a part of the hydrogen chloride gas to the step (5) for etching the silicon carbide lining of the granular silicon, and sending the rest of the hydrogen chloride gas to a slurry treatment reaction kettle for treating hydrogenated high-boiling residues; the dilute hydrochloric acid generated by the analysis is sent to sewage treatment.
Further, the urban water is subjected to flocculation, coagulation aiding, sedimentation, filtration and reverse osmosis by a desalination water station to prepare desalted water; the generated partial desalted water is subjected to a hydrogen production process to produce hydrogen and oxygen, the hydrogen is used for hydrogenation reaction, and the oxygen is used for oxidation-reduction reaction in an ore-smelting electric furnace; and the rest desalted water is used as circulating water to supplement water for the electrode of the ore-smelting electric furnace for circulating cooling.
Further, saturated steam generated by the waste heat boiler is used as heating media for nano silicon and granular silicon.
The beneficial effects are that:
(1) The nano silicon product is chemical grade industrial silicon and metallurgical grade industrial silicon, 80% of the product reaches the chemical grade nano silicon through refining, and the rest is metallurgical grade industrial silicon, so that the production requirement of the granular silicon is completely met; the oxidant oxygen needed by the nano silicon in the smelting process can be introduced through the byproduct oxygen of the hydrogen production station, so that the investment of facilities for air compression station and oxygen separation is directly saved; the high-temperature heat exchange medium circulating water of the nano silicon electric furnace electrode can be supplemented by using a water source of a particle silicon desalination water station, so that the investment of the nano silicon water station is saved, nitrogen gas and instrument gas used by nano silicon can be shared with product gas in air separation nitrogen production of the particle silicon, the construction investment of an air compression station is saved, the saturated steam generated by heat exchange of nano silicon high-temperature flue gas through a waste heat boiler can be used for supplementing a particle silicon steam heat source, the investment of a particle silicon steam generator is reduced, nano silicon sewage can be discharged to a particle silicon sewage treatment station together for treatment, the zero emission of waste water is achieved, the construction investment of the sewage treatment station of the nano silicon is reduced, the nano silicon is pneumatically conveyed to a hydrogenation procedure, and the transportation cost of the nano silicon is saved.
(2) Compared with the existing granular silicon process, the high-precision polycrystalline silicon powder produced by the nano silicon process is used as the raw material for producing granular silicon, and the nano silicon is pneumatically conveyed to the hydrogenation process, so that the transportation cost of the nano silicon is saved; the quality of the nano silicon product can be finely controlled, intermediate pollutants and non-silicon introduction can be reduced in the transportation process, and the lowest-cost transportation mode is used for achieving complete closed loop in the transportation process, so that the product quality is improved from the source.
(3) The invention adopts an FBR method and an electrothermal method nanometer silicon production process with an electrothermal furnace as main production equipment to produce solar grade granular silicon and nanometer silicon. The construction project of the nano silicon and the granular silicon is planned in a production line, so that the transportation and waste of energy sources such as water sources, electric power, raw materials and manpower are fundamentally solved, the electricity consumption is about 19.06KWh/kg, and 10 ten thousand tons of granular silicon and 15 ten thousand tons of nano silicon can be produced annually.
Drawings
The foregoing and/or other advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings and detailed description.
Fig. 1 is a process route diagram for the co-production of nano-silicon and granular silicon.
Detailed Description
The invention will be better understood from the following examples.
As shown in FIG. 1, the comprehensive power consumption of the co-production process of nano silicon and granular silicon is 19.06kWh/kg, which is far lower than the requirement that the comprehensive power consumption of the newly built polysilicon project in the photovoltaic manufacturing industry standard condition (2021 is the present) is less than 70 kWh/kg; compared with the traditional Siemens method, the process flow reduces the procedures of hydrogen recovery, reduction, rectification, crushing and silicon core recovery, and the initial investment can be reduced by 30%.
The main line process comprises the following steps:
(1) Mixing silica, cleaned coal and loosening agent proportionally, adding into ore-smelting furnace (equipped with carbon electrode), and oxidizing in oxygen atmosphereOxidation-reduction reaction is carried out under the following conditions: siO (SiO) 2 Cooling nano silicon water generated by smelting at a high temperature of 1800 ℃ with +2C→Si+2CO to prepare nano silicon blocks;
(2) Feeding the nano silicon blocks obtained in the step (1) into a milling workshop, and carrying out sieving separation after milling to obtain metallurgical grade silicon powder, high-precision polycrystalline silicon powder and fine silicon powder;
(3) The obtained metallurgical grade silicon powder and fine silicon powder are sold as products; feeding high-precision polycrystalline silicon powder, hydrogen and Silicon Tetrachloride (STC) into a circulating fluidized bed for hydrogenation reaction: 3SiCl 4 +Si+2H 2 →4SiHCl 3 ；
(4) Feeding Trichlorosilane (TCS) generated in the hydrogenation reaction in the step (3) into a silane preparation device for disproportionation reaction: 2SiHCl 3 →SiH 2 Cl 2 +SiCl 4 ，3SiH 2 Cl 2 →SiH 4 +2SiHCl 3 ；
(5) The silane gas generated by the disproportionation reaction in the step (4) is sent into a fluidized bed reactor for homogeneous decomposition reaction: siH (SiH) 4 →Si+2H 2 And after the silicon is deposited on the surface of the seed crystal to be gradually longer, carrying out aftertreatment to obtain a granular silicon product, and loading the granular silicon product into a special tank truck for selling.
In the step (2), the particles which are more than or equal to 600 mu m and are separated by sieving after grinding are metallurgical grade silicon powder; the residual particles with the particle size of 150-600 μm collected by the cyclone separator after sieving are high-precision polycrystalline silicon powder; the particles which are taken away by the cyclone separator gas and are less than or equal to 150 mu m are fine silicon powder, and the fine silicon powder is collected through a metal powder sintering membrane filter.
In the step (4), silicon tetrachloride generated by the disproportionation reaction is returned to the circulating fluidized bed in the step (3) for recycling, and hydrogenation reaction is carried out again; and the byproduct trichlorosilane generated by the disproportionation reaction reenters the silane preparation device for recycling.
In the step (5), H generated by the homogeneous decomposition reaction 2 Returning to the step (3) for hydrogenation recycling.
The invention also includes a number of process legs:
in the step (1), high-temperature flue gas generated by the submerged arc furnace enters a waste heat boiler to generate saturated steam, redundant high-temperature flue gas enters a serpentine air cooler, heat is exchanged to the atmosphere through heat exchange between outdoor air and the high-temperature flue gas in the serpentine air cooler, and the temperature of the flue gas is reduced; mixing the flue gas with the reduced temperature with the low-temperature flue gas after the waste heat boiler, and uniformly passing through a cloth bag dust remover; the micro silicon powder captured by the bag-type dust collector is collected and sold, and the collected flue gas is discharged after reaching the standard through desulfurization and denitrification treatment.
In the step (3), high-boiling substances generated by hydrogenation reaction are sent to a slag slurry treatment reaction kettle, and the high-boiling substances, hydrochloric acid and lime milk (lime powder) are mixed according to a certain proportion in the reaction kettle to treat the high-boiling substances in a harmless way; and (5) delivering the high-salt wastewater generated by the slurry treatment to sewage treatment.
The generated chlorosilane waste gas is sent to a chlorosilane waste gas treatment leaching tower, lime milk is adopted for leaching, the lime milk and the chlorosilane waste gas in the leaching tower are contacted from top to bottom for reaction, and the generated high-salt waste water is sent to sewage treatment;
the recovered water produced by sewage treatment is used as water for preparing lime milk in slag slurry treatment and chlorosilane waste gas treatment, and industrial crystalline salt byproduct is produced.
And (3) delivering the silane waste gas generated by the disproportionation reaction in the step (4) and the silane waste gas generated by the homogeneous decomposition reaction in the step (5) into a silane tail gas treatment device, diluting liquid alkali with industrial water according to a proportion, absorbing the silane tail gas, and delivering the generated wastewater to sewage treatment.
Resolving hydrogen chloride gas from 31% concentrated hydrochloric acid through a hydrochloric acid resolving tower, defogging and drying the hydrogen chloride gas, adopting a compressor to compress the hydrogen chloride, sending a part (30%) of the hydrogen chloride gas to the step (5) for etching the silicon carbide with the particle silicon lining, and sending the rest (70%) of the hydrogen chloride gas to a slurry treatment reaction kettle for treating hydrogenated high-boiling residues; the 31% concentrated hydrochloric acid of the resolved hydrogen chloride gas is changed into 1% diluted hydrochloric acid, and the 1% diluted hydrochloric acid is sent to sewage treatment for treatment, thereby realizing zero emission.
Further, the urban water is subjected to flocculation, coagulation aiding, sedimentation, filtration and reverse osmosis by a desalination water station to prepare desalted water; the generated part (10%) desalted water is subjected to a hydrogen production process to produce hydrogen and oxygen, the hydrogen is used for hydrogenation reaction, and the oxygen is used for oxidation-reduction reaction in an ore-smelting electric furnace; and the rest (90%) desalted water is used as circulating water to supplement water and supply ore-smelting electric furnace electrode for circulating cooling.
In the hydrogen production process, desalted water is subjected to electrochemical reaction under the action of a direct current electric field, oxygen is separated out from an anode, and hydrogen is separated out from a cathode, so that hydrogen and oxygen are provided for the main line 1 of the patent.
Further, saturated steam generated by the waste heat boiler is used as heating media for nano silicon and granular silicon.
The invention can further comprise the steps of pressurizing the air separation nitrogen production process by an air compressor, wherein the dew point of 30% of pressurized air is less than or equal to 50 ℃ after passing through a dryer, the pressure is more than or equal to 0.7MpaG, and the pressurized air is used as instrument gas for all the steps of nano silicon and granular silicon; 70% of the pressurized air is pre-cooled, purified, rectified and purified to reach 99.9997% of N 2 (argon content) with oxygen content of 1ppmO or less 2 The dew point is less than or equal to-70 ℃ and is used as nitrogen for all working procedures of nano silicon and granular silicon.
The invention receives the wastewater from hydrochloric acid analysis, slag slurry treatment, chlorosilane tail gas treatment and silane tail gas treatment, and the treated wastewater is used as reclaimed water to be sent to lime milk preparation and slag slurry treatment for recycling; concentrating and crystallizing the wastewater to produce crystal salt for sale.
The invention provides a thought and a method for co-production process of nano silicon and granular silicon, and the method and the way for realizing the technical scheme are numerous, the above description is only a preferred embodiment of the invention, and it should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the invention, and the improvements and modifications should be regarded as the protection scope of the invention. The components not explicitly described in this embodiment can be implemented by using the prior art.
Claims (10)
1. The co-production process of the nano silicon and the granular silicon is characterized by comprising the following steps of:
(1) Mixing silica, a reducing agent and an additive according to a proportion, adding the mixture into an ore-smelting electric furnace, and carrying out oxidation-reduction reaction to obtain nano silicon blocks;
(2) Feeding the nano silicon block obtained in the step (1) into a milling workshop, and grinding and screening to obtain metallurgical grade silicon powder, high-precision polycrystalline silicon powder and fine silicon powder;
(3) The metallurgical grade silicon powder and the fine silicon powder are sold as products; the high-precision polycrystalline silicon powder, hydrogen and silicon tetrachloride are sent into a circulating fluidized bed to carry out hydrogenation reaction, and trichlorosilane is produced by the reaction;
(4) Sending the trichlorosilane generated in the step (3) to a silane preparation device for disproportionation reaction;
(5) And (3) delivering silane gas generated by the disproportionation reaction in the step (4) into a fluidized bed reactor to obtain a granular silicon product.
2. The process for co-production of nano-silicon and granular silicon according to claim 1, wherein in the step (2), the particles which are separated by sieving and are not less than 600 μm after grinding are used as metallurgical grade silicon powder; collecting particles with the particle diameter of 150-600 μm by a cyclone separator to be used as high-precision polycrystalline silicon powder; particles which are taken away along with the cyclone separator gas and are less than or equal to 150 mu m are fine silicon powder, and the fine silicon powder is collected through a filter.
3. The process for co-production of nano-silicon and granular silicon according to claim 1, wherein in the step (4), silicon tetrachloride generated by the disproportionation reaction is returned to the circulating fluidized bed in the step (3) for recycling, and hydrogenation reaction is carried out again; and the byproduct trichlorosilane generated by the disproportionation reaction reenters the silane preparation device for recycling.
4. The process for co-production of nano-silicon and granular silicon according to claim 1, wherein in step (5), H generated by the homogeneous decomposition reaction 2 Returning to the step (3) for hydrogenation recycling.
5. The process for co-production of nano-silicon and granular silicon according to claim 1, wherein in step (1), high-temperature flue gas generated by the submerged arc furnace enters a waste heat boiler and an air cooler; the silica fume is captured by a bag-type dust collector, and the desulfurization and denitrification treatment reaches the standard and is discharged.
6. The process for co-production of nano-silicon and granular silicon according to claim 1, wherein in the step (3), high-boiling substances generated by hydrogenation reaction are sent to a slurry treatment reaction kettle, and are mixed with hydrochloric acid and lime milk according to a certain proportion for harmless treatment, and the generated high-salt wastewater is sent to sewage treatment;
the chlorosilane waste gas generated by hydrogenation is sent to a chlorosilane waste gas treatment leaching tower, lime milk is adopted for leaching, and the generated high-salt waste water is sent to sewage treatment;
the recovered water produced by sewage treatment is used as water for preparing lime milk in slag slurry treatment and chlorosilane waste gas treatment, and industrial crystalline salt byproduct is produced.
7. The process for co-production of nano-silicon and granular silicon according to claim 1, wherein the silane waste gas generated by the disproportionation reaction in the step (4) and the silane waste gas generated by the homogeneous decomposition reaction in the step (5) are fed together into a silane tail gas treatment device, and the generated waste water is fed into sewage treatment.
8. The process for co-production of nano-silicon and granular silicon according to claim 6, wherein hydrogen chloride gas is resolved from concentrated hydrochloric acid by a hydrochloric acid resolving tower, wherein part of the hydrogen chloride gas is subjected to demisting, drying and compression treatment, and is sent to the step (5) for etching the granular silicon lining silicon carbide, and the rest of the hydrogen chloride is sent to a slurry treatment reaction kettle for treating hydrogenated high-boiling substances; the dilute hydrochloric acid generated by the analysis is sent to sewage treatment.
9. The process for co-production of nano-silicon and granular silicon according to claim 1, wherein desalinated water is produced by flocculating, setting, settling, filtering and reverse osmosis of municipal water by a desalination water station; the generated partial desalted water is subjected to a hydrogen production process to produce hydrogen and oxygen, the hydrogen is used for hydrogenation reaction, and the oxygen is used for oxidation-reduction reaction in an ore-smelting electric furnace; and the rest desalted water is used as circulating water to supplement water for the electrode of the ore-smelting electric furnace for circulating cooling.
10. The process for co-production of nano-silicon and granular silicon of claim 5, wherein saturated steam generated by the waste heat boiler is used as a heating medium for nano-silicon and granular silicon.
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