An energy-saving device for directional solidification and impurity removal of metallurgical silicon

Abstract

The invention relates to an energy saving device for the directional solidification and impurity removal of metallurgical silicon. The device is a rectangular body and comprises an upper heat preservation cover, a middle heat preservation sleeve, a lower bottom plate rail frame, a composite die, a heat conducting plate and a water-cooled copper disc, wherein the water-cooled copper disc is arranged in the middle of the lower bottom plate rail frame; the heat conducting plate is arranged on the upper part of the water-cooled copper disc; the composite die is arranged on the upper part of the heat conducting plate; the periphery of the composite die is filled with silicon carbide particles with supporting and heat preservation effects; and a sealing ring is arranged between the upper heat preservation cover and the middle heat preservation sleeve. The device is suitable for the directional solidification and non-vacuum production of the metallurgical silicon by a casting method, has lowmanufacturing cost and energy consumption and small maintenance amount, is conveniently and safely used, and is environment-friendly, directional solidification and purification effects are achieved by a simple device, product quality is improved, and production cost is reduced.

Description

technical field [0001] The invention belongs to the technical field of polysilicon purification by metallurgical methods, and in particular relates to an energy-saving device for directional solidification and impurity removal of metallurgical silicon. Background technique [0002] In order to further improve the quality of metallurgical silicon, domestic and foreign enterprises have adopted various methods and measures, such as: selecting optimal raw materials, blowing chlorine outside the furnace, refining with oxygen blowing, adding solvents, directional solidification, etc., and achieved great results in removing various impurities. good effect. Among them, the directional solidification process is an important part of the metallurgical preparation of solar-grade polysilicon. It makes the silicon ingot grow unidirectionally by controlling the temperature field change, and uses the segregation effect to separate the main metal impurity elements Fe, Al, Ca, Ti, Cu, Zn, Mn...

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Problems solved by technology

Invention patents CN85100519 "A polycrystalline silicon ingot process for directional solidification and growth of solar cells", CN101323972 "A device for directional solidification of polycrystalline silicon", CN101898763 "A method for preparing directional solidification polycrystalline silicon", CN85100529 "A kind of directional solidification growth Polysilicon Ingot Process for Solar Cells" and so on, these published patent applications are all inventions for solar cell polysilicon ingot casting process and equipment similar to polysilicon ingot furnace, because such equipment requires vacuum system, heating system, measuring Temperature systems, etc., need to remelt silicon materials in the equipment, so the equipment has the disadvantages of high cost, long production cycle, and large energy consumption for monomer solidification.

The quality of metallurgical silicon (2N grade) is 3 to 4 orders of magnitude lower than that of crystalline silicon (5 to 6N), and the impurity content is high. If the polysilicon ingot furnace is directly used for directional solidification, it will cause rapid aging of the graphite parts of the ingot furnace, and the quartz ceramic crucible The high cost of polysilicon ingot casting furnace is not suitable for metallurgical silicon directional solidification requirements

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