Method of refining silicon with non-graphite crucible on medium-frequency furnace

Abstract

The invention discloses a method of refining silicon with a non-graphite crucible on a medium-frequency furnace, wherein the method includes following steps: (1) employing a high-temperature-resistant non-graphite crucible; (2) heating the high-temperature-resistant non-graphite crucible with a graphite electrode to melt metallic silicon; (3) controlling the parameter of the medium-frequency furnace and the temperature of molten silicon to form a silicon slag protective layer on an inner wall of the crucible to protect the crucible from being eroded and polluting the molten silicon; (4) adding a slag forming agent to perform slagging refining; (5) removing floated slag and pouring out a part of molten silicon while a little of molten silicon is remained in the crucible to perform next silicon melting and slagging refining. The method is carried out with the non-graphite crucible which is long in service life and is free of problem of oxidization. The silicon slag formed on the inner wall of the crucible can protect the crucible from being eroded by a slag forming agent and meanwhile high-purity molten silicon can be insulated from the wall of the crucible to stop pollution of the cruicble to the high-purity molten silicon. Continuous production in the medium-frequency furnace is ensured since enough molten silicon is remained in the crucible of each batch.

Description

technical field [0001] The invention belongs to the technical field of polysilicon purification by metallurgy, and in particular relates to a method for refining silicon in an intermediate frequency furnace using a non-graphite crucible. Background technique [0002] Energy and ecological environment issues have always been two new global issues of concern to the world. Solar energy is considered to be the most important new energy source in the 21st century due to its advantages such as wide distribution, cleanness, and no pollution. [0003] At present, the methods for purifying solar polysilicon mainly include Siemens method, new silane method, fluidized bed method, metallurgical method, etc. Among them, metallurgical method has the characteristics of high output, low investment, low cost and no pollution. Mainly include: blowing refining method, electron beam smelting, plasma smelting method, directional solidification, slagging method, vacuum smelting method, high temp...

AI Technical Summary

Problems solved by technology

This method is only suitable for use in submerged arc furnaces, and is not suitable for refining that generally uses solid metallic silicon as raw material

There are no relevant reports on other methods of purifying silicon using non-graphite crucible intermediate frequency furnaces

Ordinary smelting process will cause the metal, B, and P of high-purity silicon to be polluted, and the pollution amount ranges from one millionth to one ten thousandth

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