Directional solidification purification device and purification method for metallurgical silicon

Abstract

The invention relates to a directional solidification and purification apparatus of metallurgical silicon, comprising a ceramic crucible, a water-cooled copper crucible, a graphite bottom carrier, a sensing coil and a lifting system; the ceramic crucible and the water-cooled copper crucible are bottomless crucibles; the ceramic crucible is coaxially mounted on the water-cooled copper crucible to form a cast separate combination crucible; the graphite bottom carrier is movably mounted in the water-cooled copper crucible and is used for preheating metallurgical silicon and carrying metallurgicalsilicon melt; the sensing coil sleeves the outer wall of the cast separate combination crucible and is used for heating the graphite bottom carrier and the metallurgical silicon melt; the lifting system is used for driving the graphite bottom carrier to lift. The bottomless seamed water-cooled copper crucible is mounted on the lower portion of the bottomless ceramic crucible so as to provide continuous directional solidification for the metallurgical silicon melt under smelting in the ceramic crucible; compared with directional solidification in the traditional bottomed ceramic crucible, theapparatus herein has the advantages that melt contamination due to the crucible during solidification can be avoided, the cool crucible is reusable, crucible loss can be reduced, and purification costis lowered.

Description

Technical field [0001] Technical Field The present invention relates to purification methods physical metallurgy, particularly to a low power, high efficiency metallurgical silicon directional solidification purification method and purification apparatus. Background technique [0002] Because of greater social development, energy consumption and enhance the awareness of environmental protection, development and utilization of clean and renewable energy has become a hot spot. Solar has widely distributed, large reserves of clean and pollution-free advantages, has been widespread concern. Photovoltaic solar energy as a way in recent years has developed rapidly. Solar grade silicon (purity ≥99.9999%) are currently the main base solar cell production, which is currently mainly by improvement of Siemens purification of metallurgical silicon (2N) resulting. Preparation of purified solar grade silicon of high purity by this technique, stable quality, but the investment, complex process,...

AI Technical Summary

Problems solved by technology

Adopting this method firstly has the problem of low purification production efficiency; secondly, because the whole batch of materials is heated and melted to form a molten pool and then solidified, the ratio of the solid-liquid interface area S to the molten pool volume V in the directional solidification purification process (S / V) is small, which is obviously not conducive to the further improvement of the impurity removal rate; moreover, ceramic crucibles are generally used for melting, which inevitably has certain pollution, and the crucibles cannot be reused, which is not conducive to the further reduction of purification costs

Although the method of electromagnetic continuous casting can effectively improve the purification efficiency, the use of slotted cold crucible will consume a large amount of induction heat, which is not conducive to the reduction of purification energy consumption.

Based on this, the current purification of metallurgical silicon by directional solidification is difficult to balance energy consumption (cost) and purification efficiency, which restricts its large-scale production and application.

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