Direct oxidation refining purification method for industrial silicon melt

An oxidative refining and industrial silicon technology, applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve the problem of poor removal of element P, and achieve the effects of low cost, high removal rate and low investment

Inactive Publication Date: 2009-07-15
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

AlemanyC, a joint laboratory of France and Canada, published a paper "Refining of metallurgical-grade silicon by inductive plasma" (2002, 72(1-4): 41-48) on "Sol.Energy Mater.Sol.Cells", etc. using plasma flame Gas blowing refining, this method has a good removal efficiency for many impurities in si

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0015] Example 1: Add 5 kg of molten industrial silicon with a purity of 98% by weight or more into the graphite crucible of a heating converting furnace through a tundish, and use intermediate frequency induction heating to keep the temperature of the silicon melt at 1450-1500°C. First, blow compressed air and 55 wt% SiO into the silicon melt 2 -45% by weight CaO composed of gas-solid mixture, gas-solid product ratio is 40:1, gas-solid mixture flow rate is 10L / min, silicon metal elements such as Al, Ca, Ti, Na, Mg are removed, refining time is 1h, The slag phase is removed from the surface of the molten silicon; then the compressed air is turned off, and a mixed gas of Ar and 10% water vapor is blown into the melt. The gas flow rate is 10L / min, the temperature is controlled at 1550°C, the system pressure is 90000Pa, and the blowing time 1.5h; change to blowing in Ar+(10vol%)H 2 The gas flow rate is 10L / min, the melt temperature is still controlled at 1500~1550℃, the system pressu...

Example Embodiment

[0016] Example 2: Add 5 kg of molten industrial silicon through a tundish to the graphite crucible of the heating blowing furnace, and use intermediate frequency induction heating to keep the temperature of the silicon melt at 1450-1500°C. First, blow compressed air and 60% SiO into the silicon melt 2 A gas-solid mixture composed of -40% CaO, with a gas-solid ratio of 30:1. The gas-solid mixture flow rate is 15L / min. Silicon metal elements such as Al, Ca, Ti, Na, Mg, etc. are removed. The refining time is 1h. The slag phase is removed from the surface of the molten silicon; then the compressed air is turned off, and Ar-(15% by volume) H is blown into the melt 2 O mixed gas, gas flow rate 10L / min, temperature control at 1550℃, system pressure 90000Pa, blowing time 1.5h; change to blowing Ar+(20% volume) H 2The gas flow rate is 10L / min, the melt temperature is still controlled at 1550°C, the system pressure is 90000Pa, and the blowing time is maintained for 1.5h; after the refining,...

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PUM

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Abstract

The invention relates to a directly oxidizing refining and purifying method for industrial silicon melt, which comprises the following steps: adding melt state industrial silicon into a graphite crucible of a heating converting furnace through a pouring box, keeping the temperature of the silicon melt between 1450 and 1600 DEG C by adopting the intermediate sensing heating way, blowing the gas-solid mixture of compressed air and SiO2-CaO slag oxidant powder into the silicon melt to be oxidized and refined, removing most part of metallic impurity Al, Ca, Ti and the like and a small amount of impurity element B; and then closing the compressed air, blowing oxidized gas H2O steam, removing the residual metallic impurity and non-metallic impurity B; and finally, blowing H2 to remove the impurity element P in silicon. The invention achieves the purposes of reducing metallic impurity in the silicon to be less than 1.0 ppmw, reducing the non-metallic impurities B and P respectively to be less than 0.2 ppmw and 0.5 ppmw, and increasing the t electric resistivity to be larger than 2.5 Omega*cm.

Description

1. Technical field [0001] The invention relates to a method for directly oxidizing, refining and purifying industrial silicon melt, and belongs to the technical field of purifying industrial silicon materials by metallurgical methods. 2. Background technology [0002] Industrial silicon (MG-Si) mainly contains metal impurities such as Fe, Al, Ca and non-metallic impurities such as B, P, C, O, etc. The purity is generally above 98%, and the total content of impurities is usually higher than 10000ppm; solar-grade silicon The purity requirement of (SoG-Si) is 5N~7N. In order to ensure the required photoelectric conversion efficiency, the total impurity content in silicon should not exceed 50ppmw, usually Fe, Al, Ca and other metal impurities are below 5.0ppmw, B, P impurities are low At 1.0ppmw, C, O, etc. are below 5.0ppmw. In order for solar-grade silicon to be widely used, low-cost and high-volume production processes must be used. [0003] In 2007, global solar photovolta...

Claims

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Application Information

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IPC IPC(8): C01B33/037
Inventor 戴永年马文会杨斌伍继君王飞刘大春徐宝强谢克强周阳姚耀春郁青春秦博曲涛邓勇熊恒汪竞福刘永成周晓奎
Owner KUNMING UNIV OF SCI & TECH
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