Polycrystalline silicon preparation method

A technology of polysilicon and silicon liquid, applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve the problems of poor impurity removal effect and high cost of polysilicon process, and achieve the effect of less pollution, low cost and good effect

Active Publication Date: 2013-05-15
福建兴朝阳硅材料股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In view of the defects such as high cost and poor impurity removal effect in t

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0038] Example 1

[0039] (1) Weigh 0.6t of mixed slag, NaCl-KCl-SiO 2 The components by weight percentage are: NaCl is 20%, KCl is 20%, SiO 2 To 60%, put the mixed slag system into the graphite crucible of the intermediate frequency furnace to heat and melt, and keep the slag liquid temperature at 1450°C;

[0040] (2) In the process of producing silicon from the submerged arc furnace, control the quality of the silicon liquid to 1t, ensure that the mass ratio of the slag liquid to the silicon liquid is 0.6:1, and continuously inject a mixture of chlorine, oxygen and nitrogen into the bottom of the ladle. Its composition The percentage by volume is: 40% for chlorine, 20% for oxygen, 40% for nitrogen, and a ventilation flow of 5m 3 / h, pressure is 3atm, ventilation time is 1h;

[0041] (3) After the silicon output is completed, pour the slag liquid in the crucible of the intermediate frequency furnace into the ladle for refining. At the same time, turn on the ion generator to partiall...

Example Embodiment

[0052] Example 2

[0053] (1) Weigh 0.8t of mixed slag, NaCl-KCl-SiO 2 The components by weight percentage are: NaCl is 25%, KCl is 25%, SiO 2 To 50%, put the mixed slag system into the graphite crucible of the intermediate frequency furnace to heat and melt, and keep the slag liquid temperature at 1600°C;

[0054] (2) In the process of producing silicon from the submerged arc furnace, control the quality of the silicon liquid to 1t, ensure that the mass ratio of the slag liquid to the silicon liquid is 0.8, and continuously inject a mixture of chlorine, oxygen and nitrogen into the bottom of the ladle, and its composition is by volume The percentages are: 60% for chlorine, 30% for oxygen, 10% for nitrogen, and a ventilation flow of 12m 3 / h, the pressure is 9atm, the ventilation time is 3h;

[0055] (3) After the silicon output is completed, pour the slag liquid in the crucible of the intermediate frequency furnace into the ladle for refining, and turn on the ion generator at the sa...

Example Embodiment

[0066] Example 3

[0067] (1) Weigh 1t of mixed slag, NaCl-KCl-SiO 2 The components by weight percentage are: NaCl is 30%, KCl is 25%, SiO 2 45%, put the mixed slag system into the graphite crucible of the intermediate frequency furnace to heat and melt, and keep the slag liquid temperature at 1550°C;

[0068] (2) In the process of producing silicon from the submerged arc furnace, control the quality of the silicon liquid to 1t, ensure that the mass ratio of the slag liquid to the silicon liquid is 1, and continuously inject a mixture of chlorine, oxygen and nitrogen into the bottom of the ladle, and its composition is by volume The percentages are: chlorine is 50%, oxygen is 25%, nitrogen is 25%, and the ventilation flow is 10m 3 / h, pressure is 6atm, ventilation time is 2h;

[0069] (3) After the silicon is finished, pour the slag liquid in the crucible of the intermediate frequency furnace into the ladle for refining, and turn on the ion generator to partially ionize the mixed gas...

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Abstract

The invention discloses a polycrystalline silicon preparation method, which comprises the following steps of: refining silicon liquid in a two-man ladle by the combination of gas blowing, NaCl, KCl and SiO2 slag formers and plasmas to remove boron impurities, wherein oxidizing gases are ionized into plasma gas, the plasma gas is continuously fed into the silicon liquid for 1-3 h from the bottom of the two-man ladle, and reaction is performed in the two-man ladle; after the reaction is completed, carrying out treatment on the obtained product so as to obtain low-phosphorus-boron metal silicon; carrying out crushing, grinding and acid-washing on silicon ingots, washing, and drying; melting silicon powder subjected to acid-washing into silicon liquid through heating, and carrying out heat preservation; placing a graphite plate on the surface of the silicon liquid, enabling the bottoms of the graphite plate and a graphite crucible to be respectively connected with negative and positive poles of an external direct-current voltage, wherein the exerted direct-current voltage is 10-100 V; and after carrying out electrification 2-4 h, in an electrified state, dropping the graphite crucible at a speed of 0.10-0.15 mm/min to leave a heating area, carrying out directional solidification, after the silicon ingots are cooled, taking out the silicon ingots, and cutting off an upper impurity gathering area so as to obtain purified 6N polycrystalline silicon. The method is good in removal effect on impurities such as boron, metals and the like, low in cost, and environment-friendly.

Description

technical field [0001] The invention relates to the field of purification of solar-grade polysilicon, in particular to a method for removing boron and metal impurities for preparing solar-grade polysilicon. 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 preparation technologies and processes for solar polysilicon with low cost and low energy consumption, such as improved Siemens method, new silane method, fluidized bed method, Metallurgy etc. Among them, the process of purifying polysilicon by metallurgy is relatively simple, the cost is low, and the pollution to the environment is relatively small, and it has become the main development direction of solar-grade polysilicon. [0003] The purity of solar p...

Claims

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Application Information

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IPC IPC(8): C01B33/037
Inventor 李伟生龚炳生王晓艳
Owner 福建兴朝阳硅材料股份有限公司
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