T/CSP 12-2024 Particle technology Silicon powder recovery process specifications Melting method

Scope

Scope: This document defines the terms and definitions of silicon particles in silicon sludge generated during the melting recovery process of polycrystalline silicon ingots or monocrystalline silicon ingot slices; describes the recovery principle; establishes the recovery process; and stipulates the requirements for recovery product quality, resource conservation, and environmental protection. This document is applicable to the recovery of silicon sludge with an oxygen content of less than 10 wt% (excluding cutting fluid) generated during the crystalline silicon slicing process; Main technical content: The melting method, as the current main silicon sludge recovery process, plays an important role in the photovoltaic industry. This process efficiently converts silicon sludge into high-value silicon particles, effectively achieving the recycling and reuse of silicon resources. During the crystalline silicon steel wire slicing process, the loss rate at the cut site is about 35%. After filtration, it is produced in the form of silicon sludge, causing economic losses of billions of yuan each year. At present, there are dozens of silicon sludge recovery enterprises in China, all of which use the melting method to melt silicon sludge into silicon ingots, crush and grade them, and sell them in the form of silicon particles. However, the melting of silicon sludge suffers from high energy consumption, low product yield, and poor quality. To address these issues, this document systematically classifies silicon sludge raw materials. In view of the characteristics of silicon sludge with fine particle size, high reactivity, easy oxidation, and difficult melting, it stipulates the disposal methods of silicon sludge and significantly improves the yield and quality of silicon sludge through pre-treatment modification and flux-aided melting.

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