Method for Refining Solar Grade (SoG) Silicon by Using Physical Metallurgy

摘要

The present invention discloses a method for physically refining solar grade silicon comprises: firstly, by using a vacuum induction furnace, selecting a high oxidizing crucible to avoid carbon pollution; secondly, conducting the vacuum-pumping during the heating process; thirdly, injecting a protective gas, after the smelting temperature reaches a predetermined temperature, the powerful oxidizing gas (chlorine) is injected into the bottom of the crucible; fourthly, producing chemical reaction with the powerful oxidizing gas and impurity such as Fe—Al—Ca—P—V, so that the reaction resultant is gasified, while the power oxidizing gas stirs with the metallic silicon liquation, and preserving the temperature; fifthly, injecting the refined metallic silicon into a pouring box to enter into a oriented crystallization procedure. The present invention has following advantages: being easy and convenient to be implemented, rapid heating, no pollution, and the purity of the silicon material refined by using the method in the present invention can be graded to 5N or more.