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Device and method for purifying polycrystalline silicon

A purification method and polysilicon technology, which is applied in the growth of polycrystalline materials, chemical instruments and methods, crystal growth, etc., can solve the problems of limited application range, low distribution coefficient, limited silicon, etc., and achieve high impurity removal efficiency and slag use The effect of less amount and reducing the amount of slag

Inactive Publication Date: 2010-06-09
XIAMEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The lower distribution coefficient determines that if a lower B content is to be obtained, a higher slag-gold ratio is required. Assuming that the B distribution coefficient is 2, if silicon is to be reduced from B content of 10ppmw to below 1ppmw, the slag-silicon distribution ratio The requirement is 3:1, such a large amount of slag is not only costly, but also the silicon that can be processed at one time is relatively limited
The density of Na-based slag is generally lower than that of silicon liquid to form scum, which can be treated by removing slag and adding slag in batches to reduce the amount of slag used. 2 O is easily decomposed into simple Na at high temperature and is volatile, so it is not widely used in industry

Method used

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  • Device and method for purifying polycrystalline silicon
  • Device and method for purifying polycrystalline silicon

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0051] 150kg of silicon (lump) and 150kg of CaO (53%wt)-SiO 2 (40%wt)-CaF 2(7%wt) slag (slag-silicon ratio is 1: 1) mixes and puts into the smelting crucible 3 of primary slagging, the CaO (53%wt)-SiO of 150kg 2 (40%wt)-CaF 2 (7%wt) slag is put into the secondary slagging melting crucible 7, start the intermediate frequency heating, and the power is controlled at 70KW-200KW. After the silicon and slag are completely melted, lower the stirring bar above the silicon liquid to preheat. After fully preheating Insert a stirring rod 2 cm away from the bottom of the crucible, and stir at a speed of 400 rpm. The reaction temperature is controlled at about 1700° C., and the reaction time is 1 h. After sufficient slagging, lift the graphite stirring rod away from the silicon liquid, and slowly and continuously add 20kg of BaCO into the melt 3 After the slag and silicon are obviously stratified, start the pneumatic two-way valve to slowly tilt to the right to cast, wait for most of th...

Embodiment 2

[0053] Technological process is with embodiment 1. Silicon material is 200kg, slag is 100kg, and slag-silicon ratio is 1: 2, and the composition of slag is the same as embodiment 1. The rotation speed of the stirring bar was 600 rpm, the reaction temperature was controlled at about 1700° C., and the reaction time was 30 min. BaCO 3 The addition amount is 20Kg, and the final sampling test shows that the P content is 2ppmw, the B content is 0.8ppmw, and the purity of the polysilicon is 99.9996%.

Embodiment 3

[0055] Technological process is with embodiment 1. The silicon material is 200Kg, the slag is 100kg, the slag-silicon ratio is 1:2, and the composition of the slag is CaO(40%wt)-SiO 2 (40%wt)-CaF 2 (20%wt), the rotating speed of the stirring rod is 600rpm, the reaction temperature is controlled at about 1700°C, and the reaction time is 30min. BaCO 3 The addition amount is 20kg, and the final sampling test shows that the P content is 3ppmw, the B content is 1.2ppmw, and the purity of the polysilicon is 99.9994%.

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Abstract

The invention provides a device and a method for purifying polycrystalline silicon, relates to the polycrystalline silicon, and provides the device and the method for purifying the polycrystalline silicon with lower cost and higher efficiency. The device is provided with a primary smelt crucible, a secondary smelt crucible, a dreg holding crucible after primary slagging and a secondary insulating ladle. The method comprises the following steps: uniformly mixing silicon and dreg and putting the mixture in the primary smelt crucible, putting the dreg in the secondary smelt crucible for heating until the dreg is melted; preheating a stirring rod after materials in the primary smelt crucible are melted; lifting the stirring rod after reaction, and adding BaCO3 into the mixture; turning the primary smelt crucible rightwards for casting after demixing, stopping casting after most silicon solution flows into the secondary smelt crucible and dreg solution starts to flows into the secondary smelt crucible, turning the primary smelt crucible rightwards for casting, and pouring the dreg solution in the secondary smelt crucible into the dreg holding crucible after primary slagging for solidifying; preheating the stirring rod, lifting the stirring rod after the reaction, adding BaCO3 into the secondary smelt crucible, turning the secondary smelt crucible rightwards for casting after demixing, and pouring all melt into the insulating ladle for standing, demixing and solidifying; and grinding and acid pickling silicon after the silicon is taken out, and directionally solidifying the silicon.

Description

technical field [0001] The invention relates to polysilicon, in particular to a polysilicon purification device and purification method. Background technique [0002] In recent years, the continuous rise of oil prices and the increasingly serious environmental pollution caused by traditional energy sources have become two major problems facing the sustainable economic development of various countries. Solar energy has become an important way to solve the energy crisis and environmental degradation due to its wide distribution, clean and non-polluting advantages. At present, the vast majority of conversion materials in the solar cell industry use crystalline silicon materials (polysilicon), and their raw materials are mainly obtained by chemical methods, namely improved Siemens method, silane method and fluidized bed method. These methods not only require large investment, high energy consumption, and long cycle time, but generally a production line with an annual output of ...

Claims

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Application Information

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IPC IPC(8): C30B29/06C01B33/037
Inventor 罗学涛陈文辉李锦堂龚惟扬沈晓杰陈朝
Owner XIAMEN UNIV