CN111252769A - Preparation method of solar polycrystalline silicon - Google Patents
Preparation method of solar polycrystalline silicon Download PDFInfo
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- CN111252769A CN111252769A CN201811453156.XA CN201811453156A CN111252769A CN 111252769 A CN111252769 A CN 111252769A CN 201811453156 A CN201811453156 A CN 201811453156A CN 111252769 A CN111252769 A CN 111252769A
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- 229910021420 polycrystalline silicon Inorganic materials 0.000 title claims abstract description 11
- 238000002360 preparation method Methods 0.000 title claims abstract description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 49
- 239000011863 silicon-based powder Substances 0.000 claims abstract description 30
- 239000000463 material Substances 0.000 claims abstract description 26
- 238000002386 leaching Methods 0.000 claims abstract description 23
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 19
- 239000010703 silicon Substances 0.000 claims abstract description 19
- 239000002253 acid Substances 0.000 claims abstract description 18
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 11
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims abstract description 8
- 238000007670 refining Methods 0.000 claims abstract description 8
- 238000000227 grinding Methods 0.000 claims abstract description 6
- 229920005591 polysilicon Polymers 0.000 claims abstract description 6
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 5
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 5
- 238000005520 cutting process Methods 0.000 claims abstract description 3
- 238000007711 solidification Methods 0.000 claims abstract description 3
- 230000008023 solidification Effects 0.000 claims abstract description 3
- 238000009849 vacuum degassing Methods 0.000 claims abstract description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 17
- 239000012535 impurity Substances 0.000 claims description 15
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 14
- 239000012153 distilled water Substances 0.000 claims description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 8
- 238000003828 vacuum filtration Methods 0.000 claims description 7
- 229910052742 iron Inorganic materials 0.000 claims description 6
- 238000005406 washing Methods 0.000 claims description 6
- 229910052786 argon Inorganic materials 0.000 claims description 4
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 4
- 239000007789 gas Substances 0.000 claims description 3
- 230000003472 neutralizing effect Effects 0.000 claims description 3
- 239000002245 particle Substances 0.000 claims description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 2
- 238000003723 Smelting Methods 0.000 claims description 2
- 238000000498 ball milling Methods 0.000 claims description 2
- 238000001816 cooling Methods 0.000 claims description 2
- 238000001035 drying Methods 0.000 claims description 2
- 229910002804 graphite Inorganic materials 0.000 claims description 2
- 239000010439 graphite Substances 0.000 claims description 2
- 239000000843 powder Substances 0.000 claims description 2
- 238000007873 sieving Methods 0.000 claims description 2
- 239000002994 raw material Substances 0.000 abstract description 8
- PYRZPBDTPRQYKG-UHFFFAOYSA-N cyclopentene-1-carboxylic acid Chemical compound OC(=O)C1=CCCC1 PYRZPBDTPRQYKG-UHFFFAOYSA-N 0.000 abstract 1
- 230000003647 oxidation Effects 0.000 abstract 1
- 238000007254 oxidation reaction Methods 0.000 abstract 1
- 238000005292 vacuum distillation Methods 0.000 abstract 1
- 238000004519 manufacturing process Methods 0.000 description 7
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 238000000746 purification Methods 0.000 description 4
- 229910003822 SiHCl3 Inorganic materials 0.000 description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 238000005660 chlorination reaction Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- 239000010936 titanium Substances 0.000 description 3
- 229910052719 titanium Inorganic materials 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000002210 silicon-based material Substances 0.000 description 2
- 229910021422 solar-grade silicon Inorganic materials 0.000 description 2
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 1
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/40—Electric properties
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Silicon Compounds (AREA)
Abstract
The invention mainly discloses a preparation method of solar grade polysilicon, which adopts metallurgical grade silicon as a raw material, silicon powder materials with the granularity of more than 50 meshes are obtained after crushing and grinding, the silicon powder materials are respectively subjected to acid leaching treatment by hydrochloric acid with the concentration of 1-6mol/l, nitric acid with the concentration of 0.5-6mol/l and hydrofluoric acid with the concentration of 1-5mol/l, the acid leaching is carried out, the vacuum refining is carried out in a vacuum furnace, the vacuum refining is divided into two stages, the first stage is vacuum oxidation refining, the temperature in the furnace is controlled to be 1430-type temperature and 1500 ℃, the vacuum degree is 90000-type temperature and 1000Pa, the second stage, namely a vacuum distillation refining and vacuum degassing stage, controlling the vacuum degree of the furnace to be 10 < -2 > -10 < -5 > Pa and the temperature to be 1430 ℃ and 1500 ℃, and finally obtaining the solar grade polysilicon product through directional solidification and end cutting treatment. The purity of the silicon is more than 99.9999 percent, and the specific resistance exceeds 0.4 omega cm, so as to meet the requirements of silicon raw materials required by the solar cell industry.
Description
Technical Field
The invention relates to the technical field of solar energy, in particular to a preparation method of solar polycrystalline silicon.
Background
At present, polycrystalline silicon produced in China is produced by adopting a foreign chlorination purification technology, which is to react metallurgical-grade silicon with anhydrous hydrogen chloride to generate SiHCl3, then obtain relatively pure SiHCl3 by distillation purification, and then reduce the pure SiHCl3 by using high-purity hydrogen at the temperature of 1100 ℃ to obtain a polycrystalline silicon material. Because of foreign technical blockade, the technical level of China is low at present, and the annual output is only about 60 tons. The production technology has the advantages of large investment, high production cost, chlorine gas required in the production process and poor safety, and on the other hand, the silicon material for the solar cell is mainly from waste materials and defective products in the semiconductor industry, so that the problem of raw material supply shortage is solved, and the cost for directly producing the solar grade silicon by using the existing chlorination purification process is overhigh and the potential reduction is not large. Several experts have begun investigating new methods for solar grade silicon production.
Disclosure of Invention
The invention aims to provide a preparation method of solar grade polysilicon, which adopts metallurgical grade silicon as a raw material, and the metallurgical grade silicon is subjected to acid leaching and is added into a vacuum furnace for vacuum refining to obtain a solar grade polysilicon product, wherein the purity of the silicon is more than 99.9999%, and the specific resistance exceeds 0.4 omega cm, so as to meet the requirement of silicon raw materials required by the solar cell industry.
The invention is completed according to the following steps.
1. Breaking and grinding: taking metallurgical-grade silicon as a raw material, grinding the metallurgical-grade silicon to the granularity of 20-150 meshes, reducing iron impurities in the ground silicon powder by using a magnet, and sieving the powder in a grading manner to obtain a silicon powder material with the granularity of more than 50 meshes for further treatment, wherein the silicon powder with the granularity of less than 50 meshes can be sold as a product;
2. acid leaching:
1) firstly, carrying out acid leaching treatment on the crushed and ground silicon powder material by using hydrochloric acid with the concentration of 1-6mol/l at the leaching temperature of 40-80 ℃ for 0.5-2 days, then washing the crushed and ground silicon powder material for 2-5 times by using distilled water, and then carrying out vacuum filtration to separate the silicon powder from the leaching solution;
2) secondly leaching the separated silicon powder material for 0.5-2 days at the nitric acid concentration of 0.5-6mol/l and the temperature of 40-80 ℃, cleaning for 2-5 times by using distilled water, and then performing vacuum filtration separation to separate the silicon powder from the leachate; the process mainly removes impurities such as iron, aluminum, nickel, titanium and the like, wherein the impurities such as iron can be removed by 30-90%, the impurities such as aluminum can be removed by 40-95%, the impurities such as nickel can be removed by 20-40%, and the impurities such as titanium can be removed by 35-80%. In order to improve the reaction rate of the acid leaching process of hydrochloric acid and nitric acid, the leaching temperature is kept between 40 and 80 ℃ so as to improve the reaction rate, in order to reduce energy consumption and shorten the treatment time, the invention can also use microwave heating or ultrasonic strengthening to improve the acid leaching temperature and shorten the treatment time besides using conventional electric heating, and the power is 300-;
3) finally, hydrofluoric acid with the concentration of 1-5mol/l is adopted to soak for 0.5-1 day at the temperature of 40-80 ℃; removing silicon dioxide on the surface of the silicon powder material and oxides on the surface of impurities, cleaning for 3-8 times by using distilled water, performing vacuum filtration, separating the silicon powder material from the leaching solution, neutralizing the leaching solution and lime, and discharging according to local environmental requirements, wherein the purity of the treated silicon powder material can reach 99.9-99.99%.
Compared with the prior chlorination purification technology, the method has the advantages that:
1. the refining process after wet legal treatment is finished under the vacuum environment condition, so the equipment is simple, the auxiliary systems are few, and the safety is high; 2. the power consumption is low, the production cost is low, the power consumption can be reduced by more than 50% in the production process, and the production cost can be reduced by more than 50%;
Detailed Description
The following description is presented to disclose the invention so as to enable any person skilled in the art to practice the invention. The preferred embodiments in the following description are given by way of example only, and other obvious variations will occur to those skilled in the art.
Example one
Metallurgical grade silicon with 99.5 wt% silicon content is used as a raw material, and the main impurity components of the metallurgical grade silicon comprise 440ppmw Al, 1300ppmw Fe and 320ppmw Ca.
Crushing and grinding the raw materials, removing iron impurities brought in the crushing and ball-milling process by adopting a magnet, and then screening to obtain the silicon powder material with the particle size of 50-150 meshes.
Acid leaching the silicon powder material with 2mol/l hydrochloric acid, leaching for 1 day in a 50-60 ℃ water bath, separating acid liquid from the silicon powder material by vacuum filtration, washing for 3 times with distilled water, acid leaching the silicon powder material with 2mol/l nitric acid, leaching for 1 day in a 50-60 ℃ water bath, separating the acid liquid from the material by vacuum filtration, washing for 3 times with distilled water, neutralizing the acid leached solution with lime-nitrate to meet the discharge requirement, reducing the iron impurity content by 40 percent after the acid leaching for two times, reducing the aluminum impurity content by 50 percent, reducing the nickel impurity content by 30 percent, removing the titanium impurity by 45 percent, treating the treated silicon powder material with 3mol/l hydrofluoric acid for 12 hours, silica on the surface of the particles and oxides on the surface of impurities may be completely removed and washed 5 times with distilled water. The purity of the treated silicon powder is 99.95 percent;
drying the acid-leached silicon powder for 24 hours under the vacuum condition of 80000Pa and the temperature of 100 ℃, wherein the water content in the silicon powder material is 3 percent, adding the dried material into a vacuum furnace for refining, wherein the container is a graphite crucible, the temperature of the material is raised to 1450 ℃ and the vacuum degree of the furnace is 80000Pa by utilizing induction heating, then introducing argon plasma with the water vapor content of 1-15wt percent of the total amount of the mixed gas, the argon flow is 101/min, the pressure is 90000Pa, smelting for 4 hours under the condition, then closing the plasma, raising the vacuum degree of the furnace, keeping the vacuum degree of the furnace at 0.001Pa, keeping the temperature of the furnace at 1450 ℃ and 1500 ℃ for 6 hours, simultaneously carrying out vacuum degassing treatment, and finally carrying out directional solidification treatment, wherein the pressure of the furnace is 0.001Pa, the temperature of the silicon melt part is still kept at 1450 ℃ and 1500 ℃ and the cooling rate is 0.8 mm/min, and (4) after the temperature of the furnace is reduced to room temperature, carrying out end cutting treatment on the condensed silicon.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are merely illustrative of the principles of the invention, but that various changes and modifications may be made without departing from the spirit and scope of the invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (1)
1. A preparation method of solar grade polysilicon is characterized in that: which is completed according to the following steps,
(1) and breaking and grinding: the method comprises the following steps of crushing and grinding metallurgical-grade silicon with 99.5 wt% of silicon content, 440ppmw of Al content, 1300ppmw of Fe content and 320ppmw of Ca content, removing iron impurities brought in the crushing and ball-milling process by adopting a magnet, and then sieving to obtain silicon powder material with the particle size of 50-150 meshes;
(2) acid leaching: acid leaching the silicon powder material with 2mol/l hydrochloric acid, leaching for 1 day in a 50-60 ℃ water bath, separating acid liquid from the silicon powder material by vacuum filtration, washing with distilled water for 3 times, then performing acid leaching on the silicon powder material with 2mol/l nitric acid, leaching for 1 day in a 50-60 ℃ water bath, separating the acid liquid from the silicon powder material by vacuum filtration, washing with distilled water for 3 times, neutralizing the acid-leached solution with lime nitrate to meet the discharge requirement, treating the treated silicon powder material with 3mol/l hydrofluoric acid for 12 hours, and washing with distilled water for 5 times to obtain silicon powder with 99.95% powder purity;
(3) drying the silicon powder for 24 hours under the vacuum condition of 80000Pa and at the temperature of 100 ℃, wherein the water content in the silicon powder is 3 percent;
(4) refining the dried material in a vacuum furnace, wherein the container is a graphite crucible, the temperature of the material is raised to 1450-, then argon plasma with the content of water vapor accounting for 1-15 wt% of the total amount of the mixed gas is introduced, the flow rate of the argon gas is 10l/min, the pressure is 90000Pa, smelting for 4 hours under the condition, then closing the plasma, raising the vacuum degree of the furnace, keeping the vacuum degree of the furnace at 0.001Pa, keeping the temperature of the furnace at 1450-1500 ℃, and preserving the heat for 6 hours, and simultaneously carrying out vacuum degassing treatment, and finally carrying out directional solidification treatment, wherein the pressure of the furnace is 0.001Pa, the temperature of the silicon melt part is still 1450-1500 ℃, the cooling rate is 0.8 mm/min, and after the temperature of the furnace is reduced to room temperature, cutting the condensed silicon to obtain the solar-grade polysilicon product.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811453156.XA CN111252769A (en) | 2018-11-30 | 2018-11-30 | Preparation method of solar polycrystalline silicon |
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|---|---|---|---|
| CN201811453156.XA CN111252769A (en) | 2018-11-30 | 2018-11-30 | Preparation method of solar polycrystalline silicon |
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| CN111252769A true CN111252769A (en) | 2020-06-09 |
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| CN201811453156.XA Pending CN111252769A (en) | 2018-11-30 | 2018-11-30 | Preparation method of solar polycrystalline silicon |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112624122A (en) * | 2021-01-12 | 2021-04-09 | 昆明理工大学 | Method and device for preparing 6N polycrystalline silicon by refining industrial silicon through vacuum microwave |
-
2018
- 2018-11-30 CN CN201811453156.XA patent/CN111252769A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112624122A (en) * | 2021-01-12 | 2021-04-09 | 昆明理工大学 | Method and device for preparing 6N polycrystalline silicon by refining industrial silicon through vacuum microwave |
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| PB01 | Publication | ||
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| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20200609 |
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| WD01 | Invention patent application deemed withdrawn after publication |