Study on Physical and Chemical Properties of Industrial Silicon Slag

Silicon slag is a secondary refining byproduct from industrial silicon. The content of industrial silicon in silicon slag is about 20% , which has extremely high economic value. To better achieve the recovery and reuse of industrial silicon slag, the morphology of industrial silicon slag, the occurrence state of elements and especially the interfacial structure between silicon and slag were deeply studied in this paper. The macro and micro morphology and surface composition distribution of the silicon slag were observed by microscope, SEM-EDS and Raman spectroscopy. The phase and composition of the silicon slag were analyzed by XRF and XRD. The results showed that the purity of silicon particles in silicon slag is high up to 99% . The size and shape of silicon in silicon slag were quite different. The interface between silicon and slag is clear and there is no obvious two-phase transition zone, which is conducive to the recycling of silicon. The crushing behavior of silicon slag under different pressure was investigated. These results provide a theoretical basis for further crushing silicon slag and recovering silicon particles. When silicon slag was crushed under certain pressure, the fracture surface of large-size silicon was mostly silicon-silicon interface. Therefore, in order to realize the complete dissociation of slag and silicon, the size of the crushing particle needs to be small enough. In this paper, the physical and chemical properties of industrial silicon slag were studied, which provides a theoretical basis for the efficient separation and recovery of silicon in the slag.