CN102134077A - Method for purifying polycrystalline silicon by wet method - Google Patents
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Abstract
The invention relates to a method for purifying polycrystalline silicon by a wet method. The method comprises the following steps of: crushing polycrystalline silicon into particles with diameter of 44 to 147 microns, reacting with heating and stirring under an alkali condition, and removing impurities such as greasy dirt and the like; removing most metal impurities by the protection and complexing action of HCl and polyethylene glycol; removing the impurities in silicon oxide and silicon through hydrogen peroxide or other oxidant; removing most metal impurities comprising B and P by the protection and complexing action of the added HCl, hydrofluoric acid (HF) and polyethylene glycol; and then performing centrifugal solid-liquid separation and vacuum drying to obtain a finished product. The obtained technical index B content is reduced to be less than or equal to 0.91ppmw from 3ppmw, the P content is reduced to be less than or equal to 0.82ppmw from 3ppmw, and the TM content is reduced to be less than or equal to 50ppmw from 300ppmw.
Description
Technical field
The present invention relates to a kind of method of wet purification polysilicon, belong to metallurgical grade silicon chemical purification technical field.
Background technology
At present, along with global photovoltaic industry high speed development, as the silicon materials of upstream, how cheaply industrial silicon to be purified is high-purity level, solar level, electronic-grade, and it is more and more important to become.Known silicon method of purification mainly is divided into chemical method and metallurgy method two classes, and chemical method mainly is meant Siemens Method, silane thermal decomposition process etc., and metallurgy method is the physics method again, and the main difference between them is the silicon in the chemical method, participates in chemical reaction in purification process.Silicon in the metallurgy method, the amount of not participating in chemical reaction or participating in chemical reaction at purification process seldom.From the grade of silicon, solar level just can satisfy the application of photovoltaic industry.From being purified to originally, chemical method purified silicon main products is an electronic-grade polycrystalline silicon, and byproducts such as its scrap stock, flavoring food often are used to make solar cell material, but the cost of chemical method is far above the physics method.The advantage of physics method purifying polycrystalline silicon is that it is cheap for manufacturing cost, and technology is simple, and environmental protection pressure is little etc.Shortcoming is that operational path is unified inadequately, does not have stdn.Generally speaking, all be unable to do without wet purification in the physics method purifying polycrystalline silicon step, wet purification not only can be removed the plurality of impurities in the silicon, and is the pre-treatment work of necessity that polysilicon is purified, do before the ingot casting.In numerous wet purification technology, all be the main component of reagent with the strong oxidizer, the soluble substance of the impurity of silicon oxide surface, and formation strongly enters into solution, reaches the purpose of purification.In recent years, a lot of documents and patent have all been mentioned the wet purification polysilicon.Disclose a kind of hydrometallurgy among the Chinese patent CN101362600A and removed the method for boron in the polysilicon, it is characterized in that elder generation is broken with silica flour, the silicon after the pulverizing leaches impurity in hydrochloric acid and hydrofluoric acid, leach impurity then in the mixing solutions of ammonium chloride or ammonium chloride again.The production method that a kind of chemistry improves silicon metal purity is disclosed among the Chinese patent ZL200610170726, it is characterized in that earlier silicon being crushed to 200 orders, after screening and the magnetic separation, carry out chemical purification again, add nitric acid dousing earlier, after bleeding off nitric acid, added the salt acid soak 7 hours, added the salt acid soak again 7 hours, back adding prussic acid and hydrogen peroxide dipping 48 hours, washing and drying obtains product.A kind of method of purifying polysilicon using chemical metallurgy is disclosed among the Chinese patent CN:101311114A (200810011266.0), it is characterized in that earlier that silica flour is broken, silicon after the pulverizing soaks in sodium hydroxide solution, after put into hydrochloric acid and soak, enter in the chloroazotic acid again and soak, use hydrofluoric acid dips at last, obtain target product.Chinese patent CN:101695697A discloses a kind of method for cleaning metallurgical silicon material in (200910035672.5), it is characterized in that earlier that silica flour is broken, silicon after the pulverizing leaches impurity in hydrofluoric acid and nitric acid, and then uses deionized water wash, and strengthens washing effect with ultrasonic wave.China's document: the research of metallurgical grade silicon material wet method leaching (2 00 eight convergent points state functional materialss science and technology and industry high-rise forum 200 eight convergent points state functional materials science and technology and the high-rise forum of industry collection of thesis 2008 years, minutes ID:6794082, functional materials, supplementary issue (39) volume in 2008) in the wet purification polysilicon has been done multinomial experimental study, mainly investigated the influence of different reagent and concentration refining effect.
Summary of the invention
The object of the present invention is to provide a kind of method of wet purification polysilicon.At first with the particulate of breaking polycrystalline silicon to the 44-147 micron, under alkaline condition, impurity such as greasy dirt are removed in the heated and stirred reaction.By HCL, the protection of polyoxyethylene glycol and complexing action are removed most metallic impurity again.By hydrogen peroxide or other oxygenant, the impurity in silicon oxide material and the silicon adds HCL more again, the protection of HF and polyoxyethylene glycol and complexing action, and removal comprises B, P and most metallic impurity.Separating, obtain qualified material after the vacuum-drying then by centrifugal solid-liquid.The technical indicator B content that obtains is reduced to≤0.91ppmw from 3ppmw, and P content is reduced to≤0.82ppmw from 3ppmw, and TM content is reduced to≤50ppmw from 300ppmw.
The present invention finishes according to the following steps:
1, earlier Pure Silicon Metal is broken into the silica flour of granularity 50-200 micron;
2, silica flour is put into the solution for preparing, solution is by the sodium hydroxide of 5-20wt%, the preparation in 1: 1 by volume of the dodecyl Sodium Benzoate of 5-20wt% or the Sodium dodecylbenzene sulfonate of 5-25wt%, the quality liquid-solid ratio 3-4 of silica flour and solution: 1, stirring reaction 4-8h under 50-60 ℃ of temperature, solid-liquid separation gets first-time filtrate and a filter cake, is 7 with filter cake of deionized water wash to pH value;
3, add hydrochloric acid, the nitric acid of 5-25wt%, the ethanol of 5-20wt% or the polyoxyethylene glycol of 5-20wt% of 1: 1: 1 5-25wt% of preparation by volume again in a filter cake, liquid-solid ratio 3-4: 1, stirring reaction 6-8h under 50-60 ℃ of temperature, solid-liquid separation, getting secondary filtrate and secondary filter cake, is 7 with deionized water wash secondary filter cake to pH value then;
4, in the secondary filter cake, add the 5-20wt% hydrogen peroxide again, liquid-solid ratio 3-4: 1, uniform stirring reaction 4-8h under 50-60 ℃ of temperature;
5, added 1: 1: 1 by volume again, HCL 5wt%-20%, the HF 5-20wt% of preparation, the mixed acid liquid of ethanol 5-20wt% or polyoxyethylene glycol 5-20wt%, the mass ratio 5-6 of mixed acid liquid and secondary filter cake: 1, stirring reaction 6-8h under 50-60 ℃ of temperature, solid-liquid separation gets three filtrates and three filter cakes, is 7 with three filter cakes of deionized water wash to pH value;
6, with three filter cakes, under vacuum condition, be dried to below the 5wt%, control vacuum tightness 0.1MPa, temperature 120-130 ℃, time 3-5h obtains the qualified silica flour finished product of purity.
Principle of the present invention: at first along impurity and the fracture of crystal boundary junction, most of impurity will expose in the fragmentation of silicon materials, and in shattering process, because the oxygenizement of oxygen in the air, the surface of material can form one deck SiO
2Film, the surface of silicon will have impurity such as iron filings, greasy dirt simultaneously.Add sodium hydroxide, dodecyl Sodium Benzoate or Sodium dodecylbenzene sulfonate, purpose is to remove impurity such as the iron filings, greasy dirt of silicon face, and the molten alkaline matter of silicon face is dissolved in the solution.After the impurity of silicon face came out, HCL, nitric acid and impurity fully reacted, and in the pass into solution, polyoxyethylene glycol plays a protective role on the surface of silicon, avoided the surperficial excessively oxidated of silicon, and the impurity of the silicon face of complexing simultaneously is as impurity such as boron.After alkali cleaning and two technological processs of pickling, can not remove the impurity of silicon face fully, some impurity is embedded in the silicon, and some impurity is under the surface of silicon.At this moment add hydrogen peroxide, the impurity on abundant silicon oxide and the silicon face, silicon face generates one deck SiO
2Film.Hydrogen peroxide surface of silicon oxide not only in solution, and the special impurities of oxidation part silicon face forms oxide compound, adds HC and HF reaction again, and the oxide compound of boron, phosphorus, iron, silicon, calcium is removed, and obtains qualified finished product at last.
Advantage of comparing with known technology and positively effect
Under alkaline condition, impurity such as greasy dirt are removed in the heated and stirred reaction; By HCL, the protection of polyoxyethylene glycol and complexing action are removed most metallic impurity again; Pass through hydrogen peroxide or other oxygenant, the impurity in silicon oxide material and the silicon again; Add HCL again, the protection of HF and polyoxyethylene glycol and complexing action, removal comprises B, P and most metallic impurity; Therefore the Impurity removal in the polysilicon is removed the end.The technical indicator B content that obtains is reduced to≤0.91ppmw from 3ppmw, and P content is reduced to≤0.82ppmw from 3ppmw, TM content from 300ppmw reduce to≤50ppmw).
Embodiment
Embodiment 1: the silica flour that Pure Silicon Metal 5kg (B 3ppmw, P 3ppmw, TM 300ppmw) is crushed to granularity 50-200 micron; Put into the solution for preparing, liquid-solid ratio 3: 1, solution is made up of sodium hydroxide 5wt% and dodecyl Sodium Benzoate 5wt%, volume ratio 1: 1 stirs 6h, solid-liquid separation uniformly under 60 ℃ of temperature, getting first-time filtrate and a filter cake, is 7 with filter cake of deionized water wash to pH value; Add HCL 5wt%, HNO again
35wt%, polyoxyethylene glycol 5wt%, volume ratio 1: 1: 1, liquid-solid ratio 3: 1 evenly stirs 6h under 60 ℃ of temperature, and solid-liquid separation gets secondary filtrate and secondary filter cake, is 7 with deionized water wash secondary filter cake to pH value; Add hydrogen peroxide 5wt% again, liquid-solid ratio 3: 1, under 50 ℃ of temperature, stir 4h uniformly, add HCL5%, HF5% again, polyoxyethylene glycol 5%, volume ratio 1: 1: 1, liquid-solid ratio 5: 1 stirs 6h, solid-liquid separation uniformly under 50 ℃ of temperature, getting three filtrates and three filter cakes, is 7 with three filter cakes of deionized water wash to pH value; Then, under vacuum condition, dry to moisture content 5wt% vacuum tightness 0.1MPa, 130 ℃ of temperature, time 3.5h.Obtain the technical indicator B=0.91ppmw of product after testing, P=0.82ppmw, TM＜50ppmw.
Embodiment 2: Pure Silicon Metal 15kg (B 3ppmw, P 3ppmw, TM 300ppmw) is crushed to the 100-150 micron; Put into the solution for preparing, liquid-solid ratio 4: 1, solution is made up of sodium hydroxide 10% and dodecyl Sodium Benzoate 10%, and volume ratio 1: 1 stirs 6h uniformly under 50 ℃ of temperature, use deionized water thorough washing filter cake then, is 7 until PH; Add hydrochloric acid 10%, nitric acid 5%, polyoxyethylene glycol 10% again, volume ratio 1: 1: 1, liquid-solid ratio 4: 1 evenly stirs 6h under 50 ℃ of temperature, be 7 with deionized water thorough washing filter cake to pH value then; Add hydrogen peroxide 10% again, liquid-solid ratio 3: 1, under 60 ℃ of temperature, stir 6h uniformly, add HCL 10%, HF10% again, polyoxyethylene glycol 10%, volume ratio 1: 1: 1, liquid-solid ratio 5: 1 stirs 7h, after question response finishes uniformly under 60 ℃ of temperature, with deionized water thorough washing filter cake, be 7 until pH value; Then, under vacuum condition, dry for standby, vacuum tightness 0.1MPa, 130 ℃ of temperature, time 3h.Obtain the technical indicator B=0.85ppmw of product after testing, P=0.63ppmw, TM＜45ppmw.
Embodiment 3: Pure Silicon Metal 50kg (B 3ppmw, P 3ppmw, TM 300ppmw) is crushed to the 150-200 micron; Put into the solution for preparing, liquid-solid ratio 3: 1, solution is made up of sodium hydroxide 20% and dodecyl Sodium Benzoate 10%, and volume ratio 1: 1 stirs 8h uniformly under 50 ℃ of temperature, use the deionized water thorough washing then, is 7 until PH; Add HCL20%, HNO again
35%, polyoxyethylene glycol 10%, volume ratio 1: 1: 1, and liquid-solid ratio 3: 1 evenly stirs 8h under 50 ℃ of temperature, be 7 with deionized water thorough washing to pH value then; Add hydrogen peroxide 15% again, liquid-solid ratio 3: 1, under 60 ℃ of temperature, stir 8h uniformly, add HCL15%, HF10% again, polyoxyethylene glycol 10%, volume ratio 1: 1: 1, liquid-solid ratio 5: 1 stirs 8h, after question response finishes uniformly under 50-60 ℃ of temperature, with deionized water thorough washing silica flour, be 7 until pH value; Then, under vacuum condition, dry for standby, vacuum tightness 0.1MPa, 120 ℃ of temperature, time 4h.Obtain the technical indicator B=0.72ppmw of product after testing, P=0.58ppmw, TM＜40ppmw.
Claims (2)
1. the method for a wet purification polysilicon, it is characterized in that: it is finished according to the following steps,
1), earlier Pure Silicon Metal is broken into the silica flour of granularity 50-200 micron;
2), silica flour is put into the solution for preparing, solution is by the sodium hydroxide of 5-20wt%, the preparation in 1: 1 by volume of the dodecyl Sodium Benzoate of 5-20wt% or the Sodium dodecylbenzene sulfonate of 5-25wt%, the quality liquid-solid ratio 3-4 of silica flour and solution: 1, stirring reaction 4-8h under 50-60 ℃ of temperature, solid-liquid separation gets first-time filtrate and a filter cake, is 7 with filter cake of deionized water wash to pH value;
3), add hydrochloric acid, the nitric acid of 5-25wt%, the ethanol of 5-20wt% or the polyoxyethylene glycol of 5-20wt% of 1: 1: 1 5-25wt% of preparation by volume again in a filter cake, liquid-solid ratio 3-4: 1, stirring reaction 6-8h under 50-60 ℃ of temperature, solid-liquid separation, getting secondary filtrate and secondary filter cake, is 7 with deionized water wash secondary filter cake to pH value then;
4), in the secondary filter cake, add 5-20wt% hydrogen peroxide, liquid-solid ratio 3-4 again: 1, stirring reaction 4-8h uniformly under 50-60 ℃ of temperature;
5) mixed acid liquid that, adds HCL 5wt%-20%, HF 5-20wt%, ethanol 5-20wt% or the polyoxyethylene glycol 5-20wt% of preparation in 1: 1: 1 by volume again, the mass ratio 5-6 of mixed acid liquid and secondary filter cake: 1, stirring reaction 6-8h under 50-60 ℃ of temperature, solid-liquid separation, getting three filtrates and three filter cakes, is 7 with three filter cakes of deionized water wash to pH value;
6), with three filter cakes, dry under vacuum condition, obtain the qualified silica flour finished product of purity.
2. the method for wet purification polysilicon according to claim 1 is characterized in that: described vacuum-drying is control vacuum tightness 0.1MPa, temperature 120-130 ℃, and time 3-5h, being dried to moisture content is below the 5wt%.
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102390832A (en) * | 2011-08-18 | 2012-03-28 | 江西赛维Ldk光伏硅科技有限公司 | Method for treating waste silicon powder produced in trichlorosilane synthesis process |
| CN102981221A (en) * | 2012-12-03 | 2013-03-20 | 连云港市盛昌照明电器有限公司 | Method for manufacturing sleeve for optical fiber connector |
| CN103011168A (en) * | 2011-09-23 | 2013-04-03 | 上海普罗新能源有限公司 | Cleaning method of polycrystalline silicon raw material |
| CN103132079A (en) * | 2013-02-07 | 2013-06-05 | 睿纳能源科技（上海）有限公司 | Additive for acid texturing of diamond-wire-cutting polycrystalline silicon slices and application method thereof |
| US20140037959A1 (en) * | 2012-08-06 | 2014-02-06 | Wacker Chemie Ag | Polycrystalline silicon chunks and method for producing them |
| CN104556052A (en) * | 2014-12-26 | 2015-04-29 | 东莞市长安东阳光铝业研发有限公司 | Method for removing impurities in polycrystalline silicon |
| CN105110336A (en) * | 2015-09-15 | 2015-12-02 | 无锡荣能半导体材料有限公司 | Cleaning liquid of silicon material and cleaning method of silicon material |
| CN110342525A (en) * | 2019-07-09 | 2019-10-18 | 浙江师范大学 | A kind of method of low cost removal boron impurities in metallurgical silicon |
| CN113353938A (en) * | 2021-07-07 | 2021-09-07 | 湖北麦格森特新材料科技有限公司 | Purification process method of high-purity silicon |
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Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102390832A (en) * | 2011-08-18 | 2012-03-28 | 江西赛维Ldk光伏硅科技有限公司 | Method for treating waste silicon powder produced in trichlorosilane synthesis process |
| CN102390832B (en) * | 2011-08-18 | 2013-06-26 | 江西赛维Ldk光伏硅科技有限公司 | Method for treating waste silicon powder produced in trichlorosilane synthesis process |
| CN103011168A (en) * | 2011-09-23 | 2013-04-03 | 上海普罗新能源有限公司 | Cleaning method of polycrystalline silicon raw material |
| US20140037959A1 (en) * | 2012-08-06 | 2014-02-06 | Wacker Chemie Ag | Polycrystalline silicon chunks and method for producing them |
| US9266741B2 (en) * | 2012-08-06 | 2016-02-23 | Wacker Chemie Ag | Polycrystalline silicon chunks and method for producing them |
| CN102981221A (en) * | 2012-12-03 | 2013-03-20 | 连云港市盛昌照明电器有限公司 | Method for manufacturing sleeve for optical fiber connector |
| CN103132079A (en) * | 2013-02-07 | 2013-06-05 | 睿纳能源科技（上海）有限公司 | Additive for acid texturing of diamond-wire-cutting polycrystalline silicon slices and application method thereof |
| CN104556052A (en) * | 2014-12-26 | 2015-04-29 | 东莞市长安东阳光铝业研发有限公司 | Method for removing impurities in polycrystalline silicon |
| CN105110336A (en) * | 2015-09-15 | 2015-12-02 | 无锡荣能半导体材料有限公司 | Cleaning liquid of silicon material and cleaning method of silicon material |
| CN110342525A (en) * | 2019-07-09 | 2019-10-18 | 浙江师范大学 | A kind of method of low cost removal boron impurities in metallurgical silicon |
| CN110342525B (en) * | 2019-07-09 | 2022-02-18 | 浙江师范大学 | Method for removing impurity boron in metallurgical silicon at low cost |
| CN113353938A (en) * | 2021-07-07 | 2021-09-07 | 湖北麦格森特新材料科技有限公司 | Purification process method of high-purity silicon |
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