System and method for purifying polysilicon through continuous slagging under electric field

Abstract

The present invention discloses a system and a method for preparing high purity polysilicon through continuous slagging under an electric field effect. The system comprises: a silicon material melting device arranged in a closed chamber, a slagging agent melting device, an electrical migration device arranged in a thermal insulation chamber, a slag liquid collection tank, and a silicon liquid collection tank. According to the method, a direct current electric field perpendicular to a silicon liquid flowing direction is applied on a slowly-flowing melting silicon liquid, a layer of the slagging agent is arranged between the electrode and the silicon liquid, the silicone liquid flows while impurities migrate to the electrode direction with the electric field effect, and the impurities contact the slagging agent, and then is subjected to a reaction to be absorbed. With the method of the present invention, the use amount of the slagging agent can be reduced, the purification effect can be increased, the purity requirement on the slagging agent can be reduced, and continuous production of the high purity silicon can be achieved. In addition, the method of the present invention has advantages of good purification effect, high production efficiency, small use amount of the slagging agent, and the like.

Description

technical field [0001] The invention relates to a system and method for preparing high-purity polysilicon, specifically a system for preparing high-purity polysilicon by continuous slagging under the action of an electric field, and a method for preparing high-purity polysilicon with the system. Background technique [0002] As a method for preparing solar-grade polysilicon, metallurgy has attracted more and more attention in recent years due to its advantages of low cost and less pollution. Slagging refining is an effective means of boron removal in metallurgy, and it is widely used in production. It is also very effective in removing Ca, Al, Ti and other metals that are more easily oxidized than silicon. Usually slagging and impurity removal is to make molten silicon liquid and Na2O-CaO-SiO 2 Wait for the slag phase to contact, and use the balanced distribution of impurities in the slag phase and silicon liquid to make the impurities enter the slag phase. The ratio of th...

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Problems solved by technology

The continuity of this method is good, but during the purification process, a part of the silicon liquid with concentrated impurities needs to be recovered and purified, the production efficiency is low, there is a waste of energy, and the direct contact between the graphite electrode and the silicon liquid during the electromigration process will cause pollution. , reducing the effect of purification

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