Method for drying silicon wafer cutting waste by fluidized bed

Abstract

The invention relates to a method for drying silicon wafer cutting waste by a fluidized bed, and belongs to the technical field of recycling of silicon secondary resources. The method aims at the problems that the moisture content of a filter cake after pressure filtration of the silicon wafer cutting waste is high, and conventional steam drying, microwave drying and other methods are adopted, sothat the drying efficiency is low, the moisture removal is incomplete, and secondary oxidation of the silicon wafer cutting waste and reduction of a recovery rate of the silicon are caused and the like, and the fluidized bed drying treatment of the silicon wafer cutting waste is provided. The fluidized bed drying is carried out in advance before the silicon wafer cutting waste is subjected to high-temperature treatment and recycling, so that the moisture remaining in the filter cake of the silicon wafer cutting waste is efficiently and rapidly removed, and meanwhile, the oxidation of silicon particles in a drying process is inhibited. The moisture content in raw materials is reduced through the fluidized bed drying, so that the drying efficiency is improved, the utilization efficiency of the silicon wafer cutting waste in the subsequent process is improved, and the recovery rate of the silicon is further improved. The dried silicon wafer cutting material can be directly smelted to recover the silicon, or combined with a silicon raw material for refining.

Description

technical field [0001] The invention relates to a method for drying silicon chip cutting waste in a fluidized bed, and belongs to the technical field of silicon secondary resource regeneration and utilization. Background technique [0002] In the current crystalline silicon slicing process in China, it is inevitable that nearly 30% of high-purity silicon enters the silicon wafer cutting waste in the form of cutting debris. The resulting filter cake waste still contains 30-50% of the attached moisture residue. The residual moisture not only increases the subsequent transportation cost, but also causes the surface oxidation and heating of the ultrafine silicon particles, which not only increases the safety hazard of storage, but also reduces the silicon recovery rate. If the undried and dehydrated silicon wafer cutting waste is directly processed in the subsequent material preparation process, it is easy to cause production safety accidents, aggravate the secondary oxidation ...

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Problems solved by technology

[0003] The present invention aims at the high moisture content of the filter cake obtained after the silicon wafer cutting waste is press-filtered. Conventional steam drying, microwave drying and other methods are adopted, which not only have low drying efficiency and incomplete water removal, but also cause secondary oxidation of the silicon wafer cutting waste and To reduce the recovery rate of silicon and other problems, provide a method for fluidized bed drying of silicon wafer cutting waste, that is, to use fluidized bed drying to pretreat silicon wafer cutting waste, so that the moisture remaining in the silicon wafer cutting waste filter cake can be efficiently and quickly At the same time, it inhibits the oxidation of silicon particles in the drying process, improves the drying efficiency and reduces the moisture residue in the silicon wafer cutting waste, thereby improving the utilization efficiency of the silicon wafer cutting waste in the subsequent process and improving the recovery rate of silicon

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