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A method for synergistically purifying polysilicon with volatile slag gas

A volatile, polycrystalline silicon technology, applied in the field of metallurgy, can solve the problems of low boron impurity content, long processing time, long processing time, etc., and achieve the effects of reducing boron impurities, low cost, and reducing energy consumption for purification

Inactive Publication Date: 2019-01-18
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The processing time of this method is longer, and the energy consumption is larger, and the boron impurity content in the raw material silicon of this method is low, only 7ppmw, for the raw material with higher boron impurity content, to achieve a good purification effect, the processing time will will be longer

Method used

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  • A method for synergistically purifying polysilicon with volatile slag gas

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] 1) Weigh 5g of raw silicon with a boron content of 75ppmw, according to 23.3mol% SiO 2 -46.7mol% CaCl 2 The ratio of -30mol% CaO weighs a total of 10g of volatile slag-based slagging agents, which ensures that in the volatile slag-based slagging agents, SiO 2The molar percentage is 23.3%, CaCl 2 The molar percentage of CaO is 46.7%, and the molar percentage of CaO is 30%.

[0041] 2) The raw silicon and the ground and mixed volatile slag-based slagging agent were pre-melted at 1450° C. respectively.

[0042] 3) After adding the slag to silicon, place it in a heating furnace and melt it at 1550°C under an argon atmosphere. After it is completely melted, insert an ammonia gas pipe into the melt to blow air. The gas blown in is ammonia gas, and the flow rate of ammonia gas is 100mL / min , blowing time 60min.

[0043] 4) After the air blowing is completed, quenching and cooling are carried out.

[0044] 5) The silicon and slag were separated and sampled, and then digest...

Embodiment 2

[0053] 1) Weigh 5g of raw silicon with a boron content of 75ppmw, according to 20wt% SiO 2 -40wt% MgCl 2 The ratio of -40wt% CaO weighs 10 g of volatile slag-based slagging agents in total.

[0054] 2) The raw silicon and the ground and mixed volatile slag-based slagging agent are pre-melted at 1450-1550° C. respectively.

[0055] 3) Put the slag into silicon and put it in a heating furnace to melt at 1450°C under an argon atmosphere. After complete melting, insert an ammonia gas pipe into the melt for blowing. The blown gas is ammonia, and the flow rate of ammonia gas is 100mL / min , blowing time 60min.

[0056] 4) After the air blowing is completed, quenching and cooling are carried out.

[0057] 5) After the silicon and slag were separated and sampled, they were digested for ICP detection, and the boron content was reduced to 41.9ppmw.

Embodiment 3

[0065] 1) Weigh 5g of raw silicon with a boron content of 80ppmw, according to 20mol% SiO 2 -40wt% BaCl 2 The ratio of -40wt% CaO weighs 10 g of volatile slag-based slagging agents in total.

[0066] 2) The raw silicon and the ground and mixed volatile slag-based slagging agent are pre-melted at 1450-1550° C. respectively.

[0067] 3) Put the slag into silicon and put it in a heating furnace to melt at 1450°C under an argon atmosphere. After complete melting, insert an ammonia gas pipe into the melt for blowing. The blown gas is ammonia, and the flow rate of ammonia gas is 100mL / min , blowing time 60min.

[0068] 4) After the air blowing is completed, quenching and cooling are carried out.

[0069] 5) After the silicon and slag were separated and sampled, they were digested for ICP detection, and the boron content was reduced to 49.5ppmw.

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Abstract

The invention relates to a method for purifying polycrystalline silicon, particularly relates to a method for purifying polycrystalline silicon by coordination of volatile slag formation and gas blowing, and belongs to the technical field of metallurgy. A technical problem solved by the invention is to provide the method for purifying polycrystalline silicon by coordination of volatile slag formation and gas blowing. The method comprises the following steps: step a, mixing raw material silicon with a slag forming agent of a volatile slag system, heating to melt in an inert gas atmosphere to obtain a melt; and step b, blowing an ammonia gas mixed gas into the melt, performing heat preservation and reacting for 60-120 min, then cooling and performing silicon-slag separation to obtain purified polycrystalline silicon. The method provided by the invention purifies the polycrystalline silicon by coordination of volatile slag formation and gas blowing, realizes coordination of chlorination,oxidation and nitridation in the process of purifying the polycrystalline silicon, and can greatly reduce boron impurity in silicon within a short treatment time so as to greatly reduce energy consumption during purification.

Description

technical field [0001] The invention relates to a method for purifying polysilicon, in particular to a method for synergistically purifying polysilicon with volatile slag gas, and belongs to the technical field of metallurgy. Background technique [0002] Photovoltaic energy is one of the most important new energy sources in the 21st century. In recent years, the global photovoltaic industry has developed rapidly. In order to meet the rapid development of the photovoltaic industry, all countries in the world are committed to developing new technologies and processes for the preparation of solar polysilicon with low cost and low energy consumption, such as improved Siemens method, new silane method, and fluidized bed method. , metallurgy, etc. Among them, metallurgical purification of polysilicon has low cost and relatively little environmental pollution, and has become the main development direction of solar-grade polysilicon. [0003] The purity of solar polysilicon is re...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/037
CPCC01B33/037C01P2006/80
Inventor 王烨陈辉王辛龙袁熙志
Owner SICHUAN UNIV
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