CN116692872A - Preparation method and reaction device of low-boron and phosphorus high-purity silicon - Google Patents
Preparation method and reaction device of low-boron and phosphorus high-purity silicon Download PDFInfo
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- CN116692872A CN116692872A CN202310792984.0A CN202310792984A CN116692872A CN 116692872 A CN116692872 A CN 116692872A CN 202310792984 A CN202310792984 A CN 202310792984A CN 116692872 A CN116692872 A CN 116692872A
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- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 65
- 239000010703 silicon Substances 0.000 title claims abstract description 65
- 238000006243 chemical reaction Methods 0.000 title claims abstract description 61
- 229910052698 phosphorus Inorganic materials 0.000 title claims abstract description 36
- 239000011574 phosphorus Substances 0.000 title claims abstract description 34
- 229910052796 boron Inorganic materials 0.000 title claims abstract description 32
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 title claims abstract description 29
- 238000002360 preparation method Methods 0.000 title claims abstract description 15
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 38
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 31
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 claims abstract description 27
- 238000000034 method Methods 0.000 claims abstract description 23
- 239000006004 Quartz sand Substances 0.000 claims abstract description 21
- 238000001035 drying Methods 0.000 claims abstract description 21
- 238000007711 solidification Methods 0.000 claims abstract description 15
- 230000008023 solidification Effects 0.000 claims abstract description 15
- 238000002156 mixing Methods 0.000 claims abstract description 12
- 229920002134 Carboxymethyl cellulose Polymers 0.000 claims abstract description 11
- 239000012498 ultrapure water Substances 0.000 claims abstract description 11
- 238000003756 stirring Methods 0.000 claims abstract description 6
- 238000004519 manufacturing process Methods 0.000 claims abstract description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 63
- 239000008188 pellet Substances 0.000 claims description 40
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 34
- 229910002804 graphite Inorganic materials 0.000 claims description 34
- 239000010439 graphite Substances 0.000 claims description 34
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 34
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 32
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 20
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 20
- 239000000126 substance Substances 0.000 claims description 16
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 15
- 238000000227 grinding Methods 0.000 claims description 15
- 238000010438 heat treatment Methods 0.000 claims description 15
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 14
- 239000000463 material Substances 0.000 claims description 14
- 239000000843 powder Substances 0.000 claims description 14
- 239000002210 silicon-based material Substances 0.000 claims description 14
- 239000002245 particle Substances 0.000 claims description 11
- 239000005350 fused silica glass Substances 0.000 claims description 10
- 229910052742 iron Inorganic materials 0.000 claims description 10
- 238000001291 vacuum drying Methods 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 9
- 230000015572 biosynthetic process Effects 0.000 claims description 8
- 238000011049 filling Methods 0.000 claims description 6
- 239000003929 acidic solution Substances 0.000 claims description 5
- 239000004568 cement Substances 0.000 claims description 5
- 238000001816 cooling Methods 0.000 claims description 5
- 239000008367 deionised water Substances 0.000 claims description 5
- 229910021641 deionized water Inorganic materials 0.000 claims description 5
- 239000010419 fine particle Substances 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 238000005086 pumping Methods 0.000 claims description 5
- 230000001105 regulatory effect Effects 0.000 claims description 5
- 239000000243 solution Substances 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- 229910021420 polycrystalline silicon Inorganic materials 0.000 abstract description 10
- 229920005591 polysilicon Polymers 0.000 abstract description 10
- 238000007670 refining Methods 0.000 abstract description 6
- 239000002253 acid Substances 0.000 abstract description 2
- 238000005406 washing Methods 0.000 abstract description 2
- 238000003723 Smelting Methods 0.000 abstract 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 22
- 239000012535 impurity Substances 0.000 description 13
- 241001062472 Stokellia anisodon Species 0.000 description 4
- 239000002994 raw material Substances 0.000 description 3
- 230000002378 acidificating effect Effects 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- 238000007792 addition Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000010310 metallurgical process Methods 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000011863 silicon-based powder Substances 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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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
- C01B33/025—Preparation by reduction of silica or free silica-containing material with carbon or a solid carbonaceous material, i.e. carbo-thermal process
-
- 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
-
- 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
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Inorganic Chemistry (AREA)
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Abstract
The invention discloses a preparation method and a reaction device of low-boron and phosphorus high-purity silicon. The preparation device of the low-boron and phosphorus high-purity silicon is characterized by comprising a reaction kettle, wherein a first cavity and a second cavity are arranged in the reaction kettle. A process for preparing high-purity Si (low-boron, phosphorus) includes such steps as mixing high-purity SiC, high-purity quartz sand, high-purity ferric oxide, carboxymethyl cellulose (CMC) and high-purity water, stirring, granulating, high-temp smelting, acid washing, drying and directional solidification. The method has the advantages of simple equipment requirement, easy operation, no need of repeated refining, reduced complexity of preparing solar grade polysilicon by a metallurgical method, and high practical popularization value.
Description
Technical Field
The invention relates to the technical field of metallurgy, in particular to a preparation method and a reaction device of low-boron and phosphorus high-purity silicon.
Background
With the rapid development of the photovoltaic industry, the market demand for solar grade polysilicon increases year by year. Although the traditional chemical method such as the improved Siemens method can produce excellent polysilicon, the production cost is higher, the process is complex and the environmental pollution is large. The metallurgical method for preparing solar grade polysilicon has the advantages of low cost, low energy consumption, less investment and environmental friendliness, and becomes a current mainstream research hot spot. At present, the metallurgical method mainly uses low-purity silicon powder as a raw material, and adopts one or a combination of several methods of acid washing, slag making refining, external refining, vacuum refining, directional solidification, plasma refining and the like to purify, wherein the directional solidification can remove most of impurities, but because of the influence of segregation coefficients, boron impurities and phosphorus impurities are difficult to reach the range required by solar grade polysilicon, the method for removing one of the boron impurities or the phosphorus impurities in the silicon by one or the combination of the methods can reach the range required by the solar grade polysilicon, but the method for removing the boron impurities and the phosphorus impurities in the silicon simultaneously and reaching the range required by the solar grade polysilicon is very difficult, and the method for separately removing the boron impurities or the phosphorus impurities in the silicon has high cost and complex process. Therefore, the difficulty in removing boron impurities and phosphorus impurities in silicon has become a technical bottleneck that is difficult to break through in the metallurgical process for preparing solar grade polysilicon.
Aiming at the problems, a better method for simultaneously removing boron impurities and phosphorus impurities in silicon and reaching the range of the requirement of solar grade polysilicon is not available.
Disclosure of Invention
Aiming at the problems and the defects of the prior art, the invention provides a preparation method and a reaction device of low-boron and phosphorus high-purity silicon. The invention takes silicon carbide powder, quartz powder and ferric oxide powder with higher purity as raw materials, firstly generates silicon by a carbothermic reduction method, and then achieves the aim of producing low-boron-phosphorus high-purity silicon by acidic and directional solidification treatment. The method has the advantages of simple equipment requirement, easy operation and suitability for large-scale industrial production.
The invention is realized by the following technical scheme:
the utility model provides a preparation facilities of low boron, phosphorus high purity silicon, includes reation kettle, be equipped with cavity one, cavity two in the reation kettle, cavity one is established directly over cavity two, connect through exhaust hole one between cavity one, the cavity two, exhaust hole two is connected at cavity one top, exhaust hole two slope sets up, exhaust hole one, exhaust hole two's inner wall is equipped with the screw thread, a plurality of sawtooth groove one has been seted up at cavity one's top, a plurality of sawtooth groove two have been seted up to cavity two's top and left and right sides wall. The arrangement of the first sawtooth groove and the second sawtooth groove can reduce the loss of the silicon monoxide and slow down the diffusion speed of the silicon monoxide.
As a preferable scheme, the material of the reaction kettle is high-purity graphite.
The preparation method of the low-boron and phosphorus high-purity silicon comprises the following steps:
(1) Mixing high-purity SiC, high-purity quartz sand, high-purity ferric oxide, carboxymethyl cellulose (CMC) and high-purity water, and stirring vigorously;
(2) Uniformly mixing the mixed materials prepared in the step 1, filling the mixed materials into a mould, preparing pellets, and keeping the pellets dry in a drying kettle for a certain time, wherein the temperature of the drying kettle is set to 55-65 ℃;
(3) Placing the pellets dried in the step (2) into a second cavity of the reaction kettle as set forth in claim 1, placing high-purity ferric oxide into the first cavity, and then placing the reaction kettle into a furnace chamber of a vacuum graphite resistance furnace;
(4) Pumping the vacuum graphite resistance furnace to a vacuum state, and regulating the pressure to 10 - 2 Pa-20 - 2 Pa；
(5) Heating the vacuum graphite resistance furnace from room temperature to high temperature, keeping the heating speed uniform for a certain time at the high temperature, and then cooling the vacuum graphite resistance furnace to the ambient temperature to smelt silicon materials;
specifically, under a high-temperature environment, high-purity quartz sand in the pellets is converted into fused silica, and then the fused silica is sunk to the bottom of the pellets; at this time, molten SiO 2 Will wetWetting the SiC particles, the SiC particles cannot be coated with SiO 2 Uniformly wet and nearby molten SiO 2 Will aggregate together, and the specific reactions are: sic+2sio 2 The reaction of SiO generated by the reaction with graphite C in the reaction kettle body will take place, sio+2c=sic+co, the reaction will form silicon carbide particles, and a large amount of CO gas is formed simultaneously, and the CO gas will inhibit the reaction of sio+sic=2si+co in the reaction kettle, so that the formation of silicon will be affected, and the concentration of CO gas can be reduced by the high-purity iron oxide placed in the first cavity: fe (Fe) 2 O 3 + 3CO= 2Fe+ 3CO 2， After the reaction, the concentration difference of CO gas is formed between the second cavity and the first cavity, so that CO is easier to volatilize, the reaction SiO+SiC=2Si+CO is promoted, and the formation of silicon is promoted;
(6) Taking out the silicon material obtained in the step (5), grinding by agate, adding the silicon material powder obtained by grinding into an acidic solution, continuously maintaining for a certain time at a certain temperature, removing an oxide layer on the surface of silicon, and dissolving metal elements; meanwhile, acetic acid (20%) is added to improve the wettability of the fine particles, and the leached residues are thoroughly washed by deionized water to obtain silicon;
(7) And (3) drying the product silicon obtained in the step (6) in a vacuum drying kettle, and then carrying out directional solidification in a directional solidification furnace for one time to obtain the high-purity silicon with low boron and phosphorus.
In the preferred scheme, in the step (1), the mass percentage of the chemical components of the high-purity SiC is as follows: siC is more than or equal to 99.99%, P is less than or equal to 1ppm, and B is less than or equal to 0.5ppm; the mass percentage of the chemical components of the high-purity quartz sand is required to be SiO 2 ≥99%，Fe 2 O 3 ≤0.08%，A1 2 O 3 Less than or equal to 0.06 percent, less than or equal to 0.05 percent of CaO, less than or equal to 1ppm of P and less than or equal to 0.5ppm of B; the chemical composition of the high-purity ferric oxide requires: p is less than or equal to 1ppm, and B is less than or equal to 1ppm; the mol ratio of the high-purity SiC to the high-purity quartz sand is 2:1, and the proportion of the high-purity ferric oxide is 5-15%; the content of carboxymethyl cellulose (CMC) is 0.1-3%, and the content of high purity water is 5-10%.
In the step (2), the mixture prepared in the step (1) is uniformly mixed and filled into an iron mold, the pressure is maintained for 3-10 min under 40-45 MPa, the pellet size is 15-20 mm multiplied by 20-25 mm, and the pellet is kept dry in a drying kettle for 10-60 min, so that the strength of the pellet is required to fall freely from a height of 2 meters to the cement floor without crushing.
In the step (5), the vacuum graphite resistance furnace is heated from room temperature to high temperature 1850-1950 ℃ at a uniform heating speed of 20-25 ℃/min, maintained at 1850-1950 ℃ for 30-60min, and then cooled to ambient temperature.
Preferably, in the step (6), the powder obtained by grinding is added to a 5-10% HF solution and kept at 50-75℃for 3-6 hours continuously.
Preferably, the step (7) is to keep the product silicon in a vacuum drying kettle at 75-85 ℃ for 3-6 hours.
Compared with the prior art, the invention has the beneficial effects that: the invention takes silicon carbide powder, quartz powder and ferric oxide powder with higher purity as raw materials, firstly generates silicon by a carbothermic reduction method, and then achieves the aim of producing low-boron-phosphorus high-purity silicon by acidic and directional solidification treatment. The method has the advantages of simple equipment requirement, easy operation, no need of repeated refining, reduced complexity of preparing solar grade polysilicon by a metallurgical method, and high practical popularization value.
The high-purity graphite is used as a reaction kettle, and the high-purity ferric oxide is put into the first cavity, so that the formation of silicon can be promoted.
Drawings
The invention is described in further detail below with reference to the attached drawings and detailed description:
FIG. 1 is a schematic sectional structure of a reaction kettle of the present invention;
FIG. 2 is a schematic diagram of a cross-sectional structure of a first vent and a second vent of the present invention;
FIG. 3 is a flow chart of a method for preparing high purity silicon according to the present invention.
Detailed Description
The invention will be further illustrated with reference to specific examples.
The utility model provides a preparation facilities of low boron, phosphorus high purity silicon, includes reation kettle 1, be equipped with cavity one 2, cavity two 3 in the reation kettle 1, cavity one 2 is established directly over cavity two 3, connect through exhaust hole one 4 between cavity one 2, the cavity two 3, exhaust hole two 5 are connected at cavity one 2 tops, exhaust hole two 5 slope sets up, exhaust hole one 4, exhaust hole two 5's inner wall is equipped with screw thread 6, a plurality of sawtooth groove one 7 have been seted up at cavity one 2's top, a plurality of sawtooth groove two 8 have been seted up to cavity two 3's top and left and right sides wall.
Preferably, the material of the reaction kettle 1 is high-purity graphite.
Example 1:
the preparation method of the low-boron and phosphorus high-purity silicon comprises the following steps:
(1) Mixing high-purity SiC, high-purity quartz sand, high-purity ferric oxide, carboxymethyl cellulose (CMC) and high-purity water, and stirring vigorously;
(2) Uniformly mixing the mixed materials prepared in the step 1, filling the mixed materials into a mould, preparing pellets, and keeping the pellets dry in a drying kettle for a certain time, wherein the temperature of the drying kettle is set at 55 ℃;
(3) Placing the pellets dried in the step (2) into a second cavity 3 of the reaction kettle 1 according to claim 1, placing high-purity ferric oxide into the first cavity 2, and then placing the reaction kettle 1 into a furnace chamber of a vacuum graphite resistance furnace;
(4) Pumping the vacuum graphite resistance furnace to a vacuum state, and regulating the pressure to 10 - 2 Pa；
(5) Heating the vacuum graphite resistance furnace from room temperature to high temperature, keeping the heating speed uniform for a certain time at the high temperature, and then cooling the vacuum graphite resistance furnace to the ambient temperature to smelt silicon materials;
specifically, under a high-temperature environment, high-purity quartz sand in the pellets is converted into fused silica, and then the fused silica is sunk to the bottom of the pellets; at this time, molten SiO 2 Will wet the SiC particles, which cannot be coated with SiO 2 Uniformly wet and nearby molten SiO 2 Will aggregate together, and the specific reactions are: sic+2sio 2 The reaction of SiO3SiOco with graphite C in the reactor produces SiO2C=SicCO, which forms silicon carbide particles and large particlesThe amount of CO gas can inhibit the occurrence of reaction SiO+SiC=2Si+CO in the reaction kettle, so that the formation of silicon can be influenced, and the concentration of CO gas can be reduced by the high-purity ferric oxide placed in the first cavity 2: fe (Fe) 2 O 3 + 3CO= 2Fe+ 3CO 2， After the reaction, the concentration difference of CO gas is formed between the cavity II 3 and the cavity I2, so that CO is easier to volatilize, the reaction SiO+SiC=2Si+CO is promoted, and the silicon is promoted to be formed;
(6) Taking out the silicon material obtained in the step (5), grinding by agate, adding the silicon material powder obtained by grinding into an acidic solution, continuously maintaining for a certain time at a certain temperature, removing an oxide layer on the surface of silicon, and dissolving metal elements; meanwhile, acetic acid (20%) is added to improve the wettability of the fine particles, and the leached residues are thoroughly washed by deionized water to obtain silicon;
(7) And (3) drying the product silicon obtained in the step (6) in a vacuum drying kettle, and then carrying out directional solidification in a directional solidification furnace for one time to obtain the high-purity silicon with low boron and phosphorus.
Further, in the step (1), the mass percentage of the chemical components of the high-purity SiC is as follows: sic=99%, p=0.8 ppm, b=0.3 ppm; the mass percentage of the chemical components of the high-purity quartz sand is required to be SiO 2 =99%，Fe 2 O 3 =0.06%，A1 2 O 3 =0.04%, cao=0.03%, p=8 ppm, b=0.3 ppm; the chemical composition of the high-purity ferric oxide requires: p=0.8 ppm, b=0.8 ppm; the molar ratio of the high-purity SiC to the high-purity quartz sand is 2:1, and the proportion of the high-purity ferric oxide is 5%; carboxymethyl cellulose (CMC) content is 0.1% and high purity water content is 5%.
Further, in the step (2), after the mixture prepared in the step (1) is uniformly mixed and filled into an iron mold, the pressure is maintained for 3 min under 40 MPa, the pellet size is 15 mm multiplied by 20 mm, the pellet is kept dry in a drying kettle for 10 min, and the strength of the pellet is required to fall freely from a height of 2 meters to the cement floor without crushing.
Further, in the step (5), the vacuum graphite resistance furnace is heated from room temperature to a high temperature 1850 ℃ at a heating rate of 20 ℃/min uniformly, maintained at 1850 ℃ for 30min, and then cooled to ambient temperature.
Further, in the step (6), the powder obtained by grinding was added to a 5% HF solution and kept continuously at 50 ℃ for 3 hours.
Further, the product silicon is kept at 75 ℃ for 3 hours in a vacuum drying kettle in the step (7).
Example 2:
the preparation method of the low-boron and phosphorus high-purity silicon comprises the following steps:
(1) Mixing high-purity SiC, high-purity quartz sand, high-purity ferric oxide, carboxymethyl cellulose (CMC) and high-purity water, and stirring vigorously;
(2) Uniformly mixing the mixed materials prepared in the step 1, filling the mixed materials into a mould, preparing pellets, and keeping the pellets dry in a drying kettle for a certain time, wherein the temperature of the drying kettle is set at 60 ℃;
(3) Placing the pellets dried in the step (2) into a second cavity 3 of the reaction kettle 1 according to claim 1, placing high-purity ferric oxide into the first cavity 2, and then placing the reaction kettle 1 into a furnace chamber of a vacuum graphite resistance furnace;
(4) Pumping the vacuum graphite resistance furnace to a vacuum state, and regulating the pressure to 15 - 2 Pa，；
(5) Heating the vacuum graphite resistance furnace from room temperature to high temperature, keeping the heating speed uniform for a certain time at the high temperature, and then cooling the vacuum graphite resistance furnace to the ambient temperature to smelt silicon materials;
specifically, under a high-temperature environment, high-purity quartz sand in the pellets is converted into fused silica, and then the fused silica is sunk to the bottom of the pellets; at this time, molten SiO 2 Will wet the SiC particles, which cannot be coated with SiO 2 Uniformly wet and nearby molten SiO 2 Will aggregate together, and the specific reactions are: sic+2sio 2 The reaction of SiO3SiO + CO with graphite C in the reactor produces SiO2C=SiCoO, which forms silicon carbide particles and CO gas to inhibit SiOSiO2Si+CO reaction in the reactor, and the high purity ferric oxide in the first cavity 2 may reduce COGas concentration: fe (Fe) 2 O 3 + 3CO= 2Fe+ 3CO 2， After the reaction, the concentration difference of CO gas is formed between the cavity II 3 and the cavity I2, so that CO is easier to volatilize, the reaction SiO+SiC=2Si+CO is promoted, and the silicon is promoted to be formed;
(6) Taking out the silicon material obtained in the step (5), grinding by agate, adding the silicon material powder obtained by grinding into an acidic solution, continuously maintaining for a certain time at a certain temperature, removing an oxide layer on the surface of silicon, and dissolving metal elements; meanwhile, acetic acid (20%) is added to improve the wettability of the fine particles, and the leached residues are thoroughly washed by deionized water to obtain silicon;
(7) And (3) drying the product silicon obtained in the step (6) in a vacuum drying kettle, and then carrying out directional solidification in a directional solidification furnace for one time to obtain the high-purity silicon with low boron and phosphorus.
Further, in the step (1), the mass percentage of the chemical components of the high-purity SiC is as follows: sic=99.999%, p=0.9 ppm, b=0.4 ppm; the mass percentage of the chemical components of the high-purity quartz sand is required to be SiO 2 =99.5%，Fe 2 O 3 =0.07%，A1 2 O 3 =0.05%, cao=0.04%, p=0.9 ppm, b=0.4 ppm; the chemical composition of the high-purity ferric oxide requires: p=0.9 ppm, b=0.91 ppm; the molar ratio of the high-purity SiC to the high-purity quartz sand is 2:1, and the proportion of the high-purity ferric oxide is 10%; carboxymethyl cellulose (CMC) content is 1% and high purity water content is 8%.
Further, in the step (2), after the mixture prepared in the step (1) is uniformly mixed and filled into an iron mold, the pressure is maintained for 8min under 42 MPa, the pellet size is 18mm multiplied by 22 mm, the pellet is kept dry in a drying kettle for 30min, and the strength of the pellet is required to fall freely from a height of 2 m to the cement floor without crushing.
Further, in the step (5), the vacuum graphite resistance furnace is heated from room temperature to high temperature 1900 ℃, the heating speed is uniform at 22 ℃/min, the temperature is kept at 1900 ℃ for 45min, and then the furnace is cooled to the ambient temperature.
Further, in the step (6), the powder obtained by grinding was added to a 6% HF solution and kept continuously at 65 ℃ for 4 hours.
Further, the product silicon is kept at 80 ℃ for 4 hours in a vacuum drying kettle in the step (7).
Example 3:
the preparation method of the low-boron and phosphorus high-purity silicon comprises the following steps:
(1) Mixing high-purity SiC, high-purity quartz sand, high-purity ferric oxide, carboxymethyl cellulose (CMC) and high-purity water, and stirring vigorously;
(2) Uniformly mixing the mixed materials prepared in the step 1, filling the mixed materials into a mould, preparing pellets, and keeping the pellets dry in a drying kettle for a certain time, wherein the temperature of the drying kettle is set at 65 ℃;
(3) Placing the pellets dried in the step (2) into a second cavity 3 of the reaction kettle 1 according to claim 1, placing high-purity ferric oxide into the first cavity 2, and then placing the reaction kettle 1 into a furnace chamber of a vacuum graphite resistance furnace;
(4) Pumping the vacuum graphite resistance furnace to a vacuum state, and regulating the pressure to 20 - 2 Pa，；
(5) Heating the vacuum graphite resistance furnace from room temperature to high temperature, keeping the heating speed uniform for a certain time at the high temperature, and then cooling the vacuum graphite resistance furnace to the ambient temperature to smelt silicon materials;
specifically, under a high-temperature environment, high-purity quartz sand in the pellets is converted into fused silica, and then the fused silica is sunk to the bottom of the pellets; at this time, molten SiO 2 Will wet the SiC particles, which cannot be coated with SiO 2 Uniformly wet and nearby molten SiO 2 Will aggregate together, and the specific reactions are: sic+2sio 2 The reaction of SiO generated by the reaction with graphite C in the reaction kettle body will take place, sio+2c=sic+co, the reaction will form silicon carbide particles, and a large amount of CO gas is formed simultaneously, and the CO gas will inhibit the reaction of sio+sic=2si+co in the reaction kettle, so that the formation of silicon will be affected, and the concentration of CO gas can be reduced by the high-purity iron oxide placed in the first cavity 2: fe (Fe) 2 O 3 + 3CO= 2Fe+ 3CO 2， And the reaction will generate a concentration difference of CO gas between the second cavity 3 and the first cavity 2CO is more easily volatilized, the reaction SiO+SiC=2Si+CO is promoted, and the formation of silicon is promoted;
(6) Taking out the silicon material obtained in the step (5), grinding by agate, adding the silicon material powder obtained by grinding into an acidic solution, continuously maintaining for a certain time at a certain temperature, removing an oxide layer on the surface of silicon, and dissolving metal elements; meanwhile, acetic acid (20%) is added to improve the wettability of the fine particles, and the leached residues are thoroughly washed by deionized water to obtain silicon;
(7) And (3) drying the product silicon obtained in the step (6) in a vacuum drying kettle, and then carrying out directional solidification in a directional solidification furnace for one time to obtain the high-purity silicon with low boron and phosphorus.
Further, in the step (1), the mass percentage of the chemical components of the high-purity SiC is as follows: sic=99.99%, p=1 ppm, b=0.5 ppm; the mass percentage of the chemical components of the high-purity quartz sand is required to be SiO 2 =99.9%，Fe 2 O 3 =0.08%，A1 2 O 3 =0.06%, cao=0.05%, p=1 ppm, b=0.5 ppm; the chemical composition of the high-purity ferric oxide requires: p=1 ppm, b=1 ppm; the mol ratio of the high-purity SiC to the high-purity quartz sand is 2:1, and the proportion of the high-purity ferric oxide is 15%; carboxymethyl cellulose (CMC) content is 3% and high purity water content is 10%.
Further, in the step (2), after the mixture prepared in the step (1) is uniformly mixed and filled into an iron mold, the pressure is maintained for 10 min under 45 MPa, the pellet size is 20 mm multiplied by 25 mm, the pellet is kept dry in a drying kettle for 60min, and the strength of the pellet is required to fall freely from a height of 2 meters to the cement floor without crushing.
Further, in the step (5), the vacuum graphite resistance furnace is heated from room temperature to a high temperature of 1950 ℃ at a uniform heating rate of 25 ℃/min, kept at 1950 ℃ for 60min, and then cooled to an ambient temperature.
Further, in the step (6), the powder obtained by grinding was added to a 10% HF solution and kept continuously at 75 ℃ for 6 hours.
Further, the product silicon is kept at 85 ℃ for 6 hours in a vacuum drying kettle in the step (7).
The technical features of the present invention that are not described in the present invention may be implemented by or using the prior art, and are not described in detail herein, but the above embodiments are not limited to the embodiments, and the present invention is not limited to the above embodiments, and variations, modifications, additions or substitutions made by those skilled in the art within the spirit and scope of the present invention should also fall within the protection scope of the present invention.
Claims (8)
1. The utility model provides a preparation facilities of low boron, phosphorus high purity silicon, its characterized in that, including reation kettle (1), be equipped with first (2) of cavity, second (3) of cavity in reation kettle (1), first (2) of cavity are established directly over second (3) of cavity, connect through exhaust hole (4) between first (2) of cavity, second (3) of cavity, exhaust hole (5) are connected at first (2) top, exhaust hole (5) slope sets up, the inner wall of exhaust hole (4) of exhaust hole (5) is equipped with screw thread (6), a plurality of sawtooth groove (7) have been seted up at the top of first (2) of cavity, a plurality of sawtooth groove (8) have been seted up at the top and the left and right sides wall of second (3) of cavity.
2. The preparation device of low-boron and phosphorus high-purity silicon according to claim 1, wherein the reaction kettle (1) is made of high-purity graphite.
3. The preparation method of the low-boron and phosphorus high-purity silicon is characterized by comprising the following steps of:
(1) Mixing high-purity SiC, high-purity quartz sand, high-purity ferric oxide, carboxymethyl cellulose (CMC) and high-purity water, and stirring vigorously;
(2) Uniformly mixing the mixed materials prepared in the step 1, filling the mixed materials into a mould, preparing pellets, and keeping the pellets dry in a drying kettle for a certain time, wherein the temperature of the drying kettle is set to 55-65 ℃;
(3) Placing the pellets dried in the step (2) into a second cavity of the reaction kettle as set forth in claim 1, placing high-purity ferric oxide into the first cavity, and then placing the reaction kettle into a furnace chamber of a vacuum graphite resistance furnace;
(4) Pumping the vacuum graphite resistance furnace to a vacuum state, and regulating the pressure to 10 - 2 Pa-20 - 2 Pa；
(5) Heating the vacuum graphite resistance furnace from room temperature to high temperature, keeping the heating speed uniform for a certain time at the high temperature, and then cooling the vacuum graphite resistance furnace to the ambient temperature;
specifically, under a high-temperature environment, high-purity quartz sand in the pellets is converted into fused silica, and then the fused silica is sunk to the bottom of the pellets; at this time, molten SiO 2 Will wet the SiC particles, which cannot be coated with SiO 2 Uniformly wet and nearby molten SiO 2 Will aggregate together, and the specific reactions are: sic+2sio 2 The reaction of SiO generated by the reaction with graphite C in the reaction kettle is carried out, sio+2c=sic+co, silicon carbide particles are formed in the reaction, a large amount of CO gas is formed in the reaction kettle, the CO gas can inhibit the reaction of sio+sic=2si+co in the reaction kettle, so that the formation of silicon can be affected, and the concentration of CO gas can be reduced by the high-purity ferric oxide placed in the first cavity: fe (Fe) 2 O 3 + 3CO= 2Fe+ 3CO 2， After the reaction, the concentration difference of CO gas is formed between the second cavity and the first cavity, so that CO is easier to volatilize, the reaction SiO+SiC=2Si+CO is promoted, and the formation of silicon is promoted;
(6) Taking out the silicon material obtained in the step (5), grinding by agate, adding the silicon material powder obtained by grinding into an acidic solution, continuously maintaining for a certain time at a certain temperature, removing an oxide layer on the surface of silicon, and dissolving metal elements; meanwhile, acetic acid (20%) is added to improve the wettability of the fine particles, and the leached residues are thoroughly washed by deionized water to obtain silicon;
(7) And (3) drying the product silicon obtained in the step (6) in a vacuum drying kettle, and then carrying out directional solidification in a directional solidification furnace for one time to obtain the high-purity silicon with low boron and phosphorus.
4. The method for preparing low-boron and high-phosphorus high-purity silicon according to claim 3, wherein the steps are as follows1) The mass percentage of the chemical components of the high-purity SiC is as follows: siC is more than or equal to 99.99%, P is less than or equal to 1ppm, and B is less than or equal to 0.5ppm; the mass percentage of the chemical components of the high-purity quartz sand is required to be SiO 2 ≥99%，Fe 2 O 3 ≤0.08%，A1 2 O 3 Less than or equal to 0.06 percent, less than or equal to 0.05 percent of CaO, less than or equal to 1ppm of P and less than or equal to 0.5ppm of B; the chemical composition of the high-purity ferric oxide requires: p is less than or equal to 1ppm, and B is less than or equal to 1ppm; the mol ratio of the high-purity SiC to the high-purity quartz sand is 2:1, and the proportion of the high-purity ferric oxide is 5-15%; the content of carboxymethyl cellulose (CMC) is 0.1-3%, and the content of high purity water is 5-10%.
5. The method for preparing the low-boron and high-phosphorus high-purity silicon according to claim 1, wherein in the step (2), after uniformly mixing the mixed materials prepared in the step (1) and filling the mixed materials into an iron mold, maintaining the pressure for 3-10 min under 40-45 MPa, keeping the pellet size at 15-20 mm multiplied by 20-25 mm, and keeping the pellet in a drying kettle for 10-60 min, wherein the strength of the pellet is required to fall freely from a height of 2 m to the cement floor without crushing.
6. The method for producing low-boron, phosphorus high-purity silicon according to claim 3, wherein in the step (5), a vacuum graphite resistance furnace is heated from room temperature to a high temperature 1850-1950 ℃ at a heating rate of 20-25 ℃/min, maintained at 1850-1950 ℃ for 30-60min, and then cooled to ambient temperature.
7. The method for producing low-boron, phosphorus high-purity silicon according to claim 3, wherein in the step (6), the powder obtained by grinding is added to a 5-10% HF solution and is continuously maintained at 50-75℃for 3-6 hours.
8. A method for preparing low-boron and high-phosphorus high-purity silicon according to claim 3, wherein the step (7) is to keep the product silicon in a vacuum drying kettle at 75-85 ℃ for 3-6 hours.
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