Solid-liquid separation method and device for polycrystalline silicon ingot

Abstract

The invention provides a solid-liquid separation method and device for a polycrystalline silicon ingot. The solid-liquid separation method comprises the following steps of: fusing a silicon material into a fused silicon material in a container, when carrying out ingot pulling until the quantity of silicon liquid in the fused silicon material is 10-20%, applying pressure to the fused silicon material by utilizing a press plate matched with the cross section of the container, and extruding the silicon liquid from the fused silicon material onto the press plate along a gap between the container and the press plate under the action of pressure; stopping applying pressure to the fused silicon material after the silicon liquid is completely extruded onto the press plate; and forming a high-purity ingot below the press plate. The invention further discloses the device for realizing the solid-liquid separation method for the polycrystalline silicon ingot. According to the solid-liquid separation method and the solid-liquid separation device, lots of disadvantages in the prior art are overcome; and when the separation between the enriched impurity melts and the high-purity ingot is guaranteed, the back diffusion is restrained, and the primary product yield in the polycrystalline silicon production is improved.

Description

Technical field [0001] The present invention relates to metallurgical purification technology, in particular, and a method and equipment for separating solid and liquid from polycrystalline silicon ingots. Background technique [0002] In recent years, there has been a shortage of solar-grade polysilicon raw materials with the rapid development of the photovoltaic industry, and people have turned their attention to the preparation of silicon raw materials. The preparation of polycrystalline silicon by metallurgical method uses a large amount of low-cost metallurgical grade silicon as raw materials to directly prepare solar-grade polycrystalline silicon, which has the characteristics of short production cycle, low pollution and low cost. The directional coagulation technology in metallurgy can not only be used for the preparation of solar-grade polysilicon ingots, but also can be used to remove metal impurities with small segregation coefficients in silicon, and has become the res...

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Problems solved by technology

At present, some researchers have disclosed several silicon solid-liquid separation and purification methods in the manufacture of high-purity polysilicon ingots: such as: patent application number 201210537365.9, the patent name is "a method and equipment for directional solidification and purification of polysilicon by vacuum extraction of tailings ” patent; the patent application number is 201310011153.1, and the patent name is “polysilicon ingot casting device and ingot casting method” respectively discloses solid-liquid separation and purification methods in the manufacture of polysilicon ingots, but the yield of the above methods is still not high, about It is 70-80%, and this has caused the great waste of raw material and energy, is unfavorable for suitability for industrialized production, therefore urgently needs a kind of method and equipment that further improves yield

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