CN102530954B - Composite refining agent for secondary refining to purify industrial silicon and remove boron - Google Patents

Composite refining agent for secondary refining to purify industrial silicon and remove boron Download PDF

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CN102530954B
CN102530954B CN201210057377.1A CN201210057377A CN102530954B CN 102530954 B CN102530954 B CN 102530954B CN 201210057377 A CN201210057377 A CN 201210057377A CN 102530954 B CN102530954 B CN 102530954B
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boron
silicon
slag
industrial silicon
refining
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CN102530954A (en
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马文会
魏奎先
丁朝
伍继君
谢克强
周阳
龙萍
刘永成
陈建云
周晓奎
刘大春
杨斌
戴永年
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Sichuan Nabi Material Technology Co ltd
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Kunming University of Science and Technology
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Abstract

The invention provides a composite refining agent for secondary refining to purify industrial silicon and remove boron. The composite refining agent comprises the following components in percentage by mass: 2 to 40 percent of LiF, 50 to 95 percent of SiO2, 3 to 48 percent of basic oxide and 0 to 45 percent of other compounds. The industrial silicon containing 10-2,000ppmw of boron and serving as a raw material is mixed with the composite refining agent for secondary refining to purify the industrial silicon and remove the boron in a mass ratio of 10:1-1:10, slagging refining is carried out at the temperature of between 1,450 and 1,850DEG C for 0.5 to 15 hours, cooling is carried out, and slag and silicon are separated, so that the impurity boron, together with the slag, is removed. The composite refining agent has obvious effects; by the method, the boron content in the industrial silicon is reduced to be less than 1ppmw, and the slag and the silicon are easy to separate; the technological operation is simple, requirements on equipment are low, and the cost is low; the energy consumption is low and the pollution is light; and harmful gases are not generated in the process, the waste slag can be recycled, and environment friendliness is achieved.

Description

A kind of purifying industrial silicon through external refining is except the composite refiner of boron
Technical field
The present invention relates to the composite refiner of a kind of purifying industrial silicon through external refining except boron, belong to the technical field of metallurgy method purifying industrial silicon.
Background technology
A large amount of exploitations of whole world fossil energy are the one of the main reasons causing ecological damage, a large amount of uses of fossil energy are then the major causes causing global environmental pollution, correlative study shows, big area uses solar energy power generating electric energy, effectively can reduce the discharge of carbonic acid gas, reduce Greenhouse effect, improve terrestrial climate.According to the analysis of world energy sources authoritative institution, calculate according to the fossil energy reserves verified at present and recovery rate, Global Oil residue can adopt the time limit only 41 years, and Sweet natural gas residue can adopt the time limit 61.9, coal residue can adopt the time limit 230 years, and uranium residue can adopt the time limit 71 years.
Sun power is as a kind of safe and reliable, noiseless, the reproducible new forms of energy that pollution-free, resource is wide, because of the effect of its energy saving standard, paid attention to widely, generally acknowledge it is 21 century important new forms of energy, be widely used in generate electricity by way of merging two or more grid systems, the aspect such as civilian power generation, communal facility and integrated energy-saving building.The main exploitation mode of sun power is solar generator, solar water and solar energy power generating, and from current development trend, prior development direction is solar energy power generating.
Photovoltaic industry develop the shortage bringing solar energy level silicon (Solar Grade Silicon, SOG-Si) rapidly, cause meet photovoltaic industry require polysilicon price constantly rise.At present, solar level silicon materials do not form independently supply system, major part derives from the waste material of electronic-grade silicon and the material end to end of silicon single crystal, can not meet the demand of solar cell industry fast development far away, and raw material supply has become the bottleneck of restriction theCourse of PV Industry.Commercial, silicon is normally obtained by highly purified silicon-dioxide and coke gasification reaction in the electric arc furnace of Graphite Electrodes, and the silicon purity that this method obtains is at least 95%, is called as industrial silicon (Metallurgical Grade Silicon, MG-Si).But make solar cell, the content of some impurity element can not more than 1ppmw.Growing to the needs having solar energy level silicon in order to meet, the metallurgy method developing a kind of low cost refined silicon has been very urgent.
Slag refining is that one is relatively consuming time few, and the metallurgical grade silicon purification techniques that energy consumption is low, to the new forms of energy epoch, the development of sun power has material impact.The people such as the M. Tanahashi of Japan Nagoya university are at paper " Oxidation Removal Behavior of Boron and Local Nonequlibrium Reaction Field in Purification Process of Molten Silicon by the Flux Injection Technique " (The Minerals, Metals & Materials Society, 2006,1:173-186) in attempt to use CaO-CaF 2powder melts process metallurgical grade silicon, found that Boron contents can be reduced to about 1ppm, compared with plasma melting, not only energy-conservation, and saves time.The people such as the L.A.V. Teixeira of Tokyo Univ Japan are at paper " Behavior and State of Boron in CaO-SiO 2slags during Refining of Solar Grade Silicon " (ISIJ Int. 2009,49:777-782) middle proposition, CaO-SiO 2binary slag mixing metallurgical grade silicon is put, and oxidation refining in the induction furnace of logical argon shield under 1823K, obtains the partition ratio (L of boron impurities element b) be to the maximum and 5.5, after refining, in silicon, minimum boron content is 1.9ppmw.
Summary of the invention
The object of the invention is to, for the limitation existing for existing refining agent removal boron from industrial silicon impurity, provide a kind of purifying industrial silicon through external refining except the composite refiner of boron, realized by following technical proposal.
Purifying industrial silicon through external refining, except the composite refiner of boron, comprises the following component of mass percent: LiF is 2 ~ 40%, SiO 2be 50 ~ 95%, basic oxide are 3 ~ 48%, other compounds contents are 0 ~ 45%.
Described basic oxide, as CaO, MgO, BaO, Na 2o, K 2o etc.
Other compounds described, as Al 2o 3, CaF 2deng.
Described purifying industrial silicon through external refining removes the composite refiner of boron in use, be using boron-containing quantity be the industrial silicon of 10 ~ 2000ppmw as raw material and purifying industrial silicon through external refining except the composite refiner of boron is that 10 ︰ 1 ~ 1 ︰ 10 mix in mass ratio, slag refining 0.5 ~ 15h is carried out at 1450 ~ 1850 DEG C, then cool, finally carry out the separation of slag silicon, boron impurities is removed along with slag.
Described purifying industrial silicon through external refining except the addition sequence of composite refiner of boron be add prior to industrial silicon raw material or melt or refining time time sharing segment add or component each in refining agent added respectively or add together after component each in refining agent is mixed, but be not limited to above-mentioned addition sequence.
Described purifying industrial silicon through external refining is directly from fire door or directly to add or from modes such as fire door and breather line add simultaneously from breather line except the Adding Way of composite refiner of boron, but is not limited to above-mentioned feed postition.
Described purifying industrial silicon through external refining is except the while of composite refiner and the conventional refinery gas of boron or cross-reference.
Described conventional refinery gas be in air, oxygen-rich air, oxygen, water vapour, argon gas, nitrogen any one or multiple, but be not limited to above-mentioned gas.
In slag refining process, the impurity B oxidation in industrial silicon generates B x o y, removing of partly volatilizing in a gaseous form, portion of residual is in melt silicon.Add LiF and can reduce slag and silicon melt liquidus temperature as slag former, save energy consumption, introduce F with LiF form -the viscosity of slag can be reduced, improve fluidity of molten, slag making be reacted and carries out more complete.Further, at high temperature, impurity B remaining in the adsorbable silicon of LiF, generates Li with its generation chemical reaction xb ycompound is stayed in slag, is removed along with the excision of slag.So, utilize the characteristic of novel refining agent, reached the object removing boron from industrial silicon by external refining, for the production of the high-quality industrial silicon product of ultralow Boron contents.Experiment proves, uses this refining agent slag refining metallurgical grade silicon, in removal silicon while boron impurity, also has certain effect, as Al, Ca, P to the removal of other usual impurities in silicon.
The invention provides a kind of purifying industrial silicon through external refining except after the composite refiner of boron mixes with industrial silicon, carry out slag refining purifying industrial silicon, institute adds LiF system refining agent and not only can reduce slag and silicon melt liquidus temperature, reduce the viscosity of slag, improve fluidity of molten, and impurity B element that can be remaining in chemisorption Si, be enriched in slag with its generation chemical reaction.Utilize the characteristic of refining agent, impurity (Al, Ca, P, B) in silicon is removed by slag making, especially to the boron of one of removal impurity the most difficult in silicon, successful, for the production of the high-quality industrial silicon product of ultralow Boron contents, compared with existing refining agent used, tool of the present invention has the following advantages:
(1) Be very effective, the Boron contents in industrial silicon can be reduced to <1ppmw by the method, can be used for producing the high-quality industrial silicon of ultralow Boron contents;
(2) main compound LiF density is little, so slag system density is much smaller than other existing slag systems, larger with melt silicon difference, is easy to the separation of slag silicon;
(3) technological operation is simple, low for equipment requirements, with low cost;
(4) energy consumption is low, pollutes little, and this process does not produce obnoxious flavour, waste residue recycling capable of circulation, environmentally friendly.
Embodiment
Below in conjunction with embodiment, the present invention is further elaborated.
Embodiment 1
Taking analytical pure LiF is 1.75g, SiO 2for 18.29g, CaO are 14.96g, mix and namely obtain the composite refiner of purifying industrial silicon through external refining except boron.
Using boron-containing quantity be the industrial silicon 35g of 15ppmw as raw material and purifying industrial silicon through external refining except the composite refiner of boron is that 1 ︰ 1 mixes in mass ratio, argon gas is passed in stove, slag refining 1.5h is carried out at 1550 DEG C, then cool, finally carry out the separation of slag silicon, boron impurities is removed along with slag.Measuring Boron contents with ICPMS is 0.52ppmw, and boron clearance is 96.53%.
Embodiment 2
Taking analytical pure LiF is 7g, SiO 2for 15.4g, CaO are 12.6g, mix and namely obtain the composite refiner of purifying industrial silicon through external refining except boron.
Using boron-containing quantity be the industrial silicon 35g of 15ppmw as raw material and purifying industrial silicon through external refining except the composite refiner of boron is that 1 ︰ 1 mixes in mass ratio, argon gas is passed in stove, slag refining 3h is carried out at 1650 DEG C, then cool, finally carry out the separation of slag silicon, boron impurities is removed along with slag.Measuring Boron contents with ICPMS is 0.38ppmw, and boron clearance is 97.47%.
Embodiment 3
Taking analytical pure LiF is 14g, SiO 2for 11.55g, CaO are 9.45g, mix and namely obtain the composite refiner of purifying industrial silicon through external refining except boron.
Using boron-containing quantity be the industrial silicon 35g of 15ppmw as raw material and purifying industrial silicon through external refining except the composite refiner of boron is that 1 ︰ 1 mixes in mass ratio, argon gas is passed in stove, slag refining 5h is carried out at 1800 DEG C, then cool, finally carry out the separation of slag silicon, boron impurities is removed along with slag.Measuring Boron contents with ICPMS is 0.43ppmw, and boron clearance is 97.13%.
Embodiment 4
Taking analytical pure LiF is 7g, SiO 2for 332.5g, BaO are 10.5g, mix and namely obtain the composite refiner of purifying industrial silicon through external refining except boron.
Using boron-containing quantity be the industrial silicon 35g of 10ppmw as raw material and purifying industrial silicon through external refining except the composite refiner of boron is that 1 ︰ 10 mixes in mass ratio, slag refining 15h is carried out at 1450 DEG C, then cool, finally carry out the separation of slag silicon, boron impurities is removed along with slag.Measuring Boron contents with ICPMS is 0.35ppmw, and boron clearance is 96.5%.
Embodiment 5
Taking analytical pure LiF is 1.295g, SiO 2for 1.4g, MgO are 0.105g, Al 2o 3for 0.7g, mix and namely obtain the composite refiner of purifying industrial silicon through external refining except boron.
Using boron-containing quantity be the industrial silicon 35g of 1000ppmw as raw material and purifying industrial silicon through external refining except the composite refiner of boron is that 10 ︰ 1 mix in mass ratio, slag refining 0.5h is carried out at 1850 DEG C, then cool, finally carry out the separation of slag silicon, boron impurities is removed along with slag.Measuring Boron contents with ICPMS is 28ppmw, and boron clearance is 97.2%.
Embodiment 6
Taking analytical pure LiF is 6.6g, SiO 2for 11.6g, MgO are 1.05g, CaF 2for 15.75g, mix and namely obtain the composite refiner of purifying industrial silicon through external refining except boron.
Using boron-containing quantity be the industrial silicon 35g of 2000ppmw as raw material and purifying industrial silicon through external refining except the composite refiner of boron is that 1 ︰ 1 mixes in mass ratio, slag refining 4.5h is carried out at 1650 DEG C, then cool, finally carry out the separation of slag silicon, boron impurities is removed along with slag.Measuring Boron contents with ICPMS is 52ppmw, and boron clearance is 97.4%.

Claims (1)

1. a purifying industrial silicon through external refining is except the using method of the composite refiner of boron, it is characterized in that through the following step: using boron-containing quantity be the industrial silicon of 10 ~ 2000ppmw as raw material and purifying industrial silicon through external refining except the composite refiner of boron is that 10 ︰ 1 ~ 1 ︰ 10 mix in mass ratio, slag refining 0.5 ~ 15h is carried out at 1450 ~ 1850 DEG C, then cool, finally carry out the separation of slag silicon, boron impurities is removed along with slag, wherein purifying industrial silicon through external refining comprises the following component of mass percent except the composite refiner of boron: LiF is 2 ~ 40%, SiO 2be 50 ~ 95%, basic oxide are 3 ~ 48%, other compounds contents are 0 ~ 45%.
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CN104276572B (en) * 2013-07-02 2016-08-10 青岛隆盛晶硅科技有限公司 The slag former of polycrystalline silicon medium melting and using method thereof
CN109231216A (en) * 2018-11-19 2019-01-18 成都斯力康科技股份有限公司 Refinery practice is purified outside industrial silicon furnace
CN115852193A (en) * 2022-12-26 2023-03-28 山东创新金属科技有限公司 Aluminum alloy smelting refining agent and preparation method thereof

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CN1628076A (en) * 2002-02-04 2005-06-15 夏普株式会社 Silicon purifying method, slag for purifying silicon, and purified silicon
CN101671023A (en) * 2009-09-15 2010-03-17 厦门大学 Boron-removing purification method of polysilicon
CN102219221A (en) * 2011-06-08 2011-10-19 大连理工大学 Method for purifying polycrystalline silicon by directional solidification and slag refining

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KR20120031159A (en) * 2009-07-03 2012-03-30 미쓰비시 가가꾸 가부시키가이샤 Method for producing silicon, silicon, and panel for solar cell

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CN1628076A (en) * 2002-02-04 2005-06-15 夏普株式会社 Silicon purifying method, slag for purifying silicon, and purified silicon
CN101671023A (en) * 2009-09-15 2010-03-17 厦门大学 Boron-removing purification method of polysilicon
CN102219221A (en) * 2011-06-08 2011-10-19 大连理工大学 Method for purifying polycrystalline silicon by directional solidification and slag refining

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Address after: 615500 Yinlu Industrial Park, Dechang County, Liangshan Yi Autonomous Prefecture, Sichuan Province

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