Silicon nitride powder recycling and reusing method

Abstract

The invention discloses a silicon nitride powder recycling and reusing method, and belongs to the technical field of polycrystalline silicon ingot casting. The silicon nitride powder recycling and reusing method comprises following steps: a, acid dipping, wherein collected silicon nitride powder is immersed in hydrofluoric acid and hydrochloric acid so as to obtain an immersion solution; b, centrifugation, wherein the immersion solution obtained in step a is introduced into a centrifugation equipment for centrifugation; c, rinsing, wherein the silicon nitride obtained through centrifugation instep b is dissolved in pure water, stirring is carried out for 15 to 20min, centrifugation in step b is carried out for another time, and residual acid on the surface of silicon nitride is removed through rinsing; d, drying, wherein the silicon nitride powder cleaned through rinsing in step c is introduced into a microwave drying furnace for drying; e, crushing, wherein the silicon nitride powderdried in step d is crushed into fine powder; and f, silicon nitride crushed in step e is subjected to sieving using a sieving screen of 200 to 250 meshes. The silicon nitride powder recycling and reusing method can be used for recycling and reusing of silicon nitride, and is capable of reducing solid state waste, and reducing silicon nitride using cost.

Description

technical field [0001] The invention relates to the technical field of polysilicon ingot casting, in particular to a method for recycling silicon nitride powder. Background technique [0002] At present, the preparation method of polycrystalline silicon ingots is mainly carried out by using the directional solidification system provided by GT Solar, which usually includes steps such as heating, melting, crystal growth, annealing and cooling. In the ingot casting process, silicon nitride is used as a mold release agent (to isolate the contact between the silicon liquid and the quartz crucible at high temperature), which plays a key role in preventing the ingot from sticking to the pot and cracking. During the crucible spraying process, the suction hood will collect the silicon nitride floating in the air, and the annual collection volume is about 2T. At present, the silicon nitride collected by the suction hood is currently disposed of as solid powder waste, which not only p...

AI Technical Summary

Problems solved by technology

At present, the silicon nitride collected by the suction hood is currently disposed of as solid powder waste, which not only puts pressure on environmental protection, but also causes waste loss