Abstract: Crystalline silicon sawing waste is an important new energy solid waste. However, during the slicing and storage process, the surface of the silicon sawing waste tends to form a high melting point oxide layer, which makes the internal liquid silicon wrapped by the high melting point oxide layer during the high-temperature melting process, further resulting in longer melting time, high energy consumption, low silicon powder yield, and other challenges. Besides, low-quality silicon is recycled by the existing ordinary lime melting method due to phosphorus contamination of the silicon sawing waste from the electroplated diamond wire during the slicing process. Therefore, the silicon recycled from the melting of silicon sawing waste is a potential raw material for silicone production. In this work, silicon for organic use was successfully prepared by removing the surface oxide layer and non-metallic impurities of elemental phosphorus from crystalline silicon cutting scrap in one step using slag refining. Firstly, the high-temperature melting behavior of the oxide layer was simulated using silicon oxide. The effect of two slag systems, CaO-Al2O3-SiO2 and CaO-SiO2-CaF2, on the dissolution ratio of silicon oxide was compared. The influences of refining time (2~6 min) and refining temperature (1400, 1450, and 1500℃) on the dissolution ratio of silicon oxide were also investigated. Then, the effect of two refining slag systems on phosphorus removal was compared by using silicon sawing waste as raw material. The dissolution mechanism of the oxidation layer and phosphorus removal results were analyzed. The results showed that the dissolution of silicon oxide was mainly influenced by the viscosity of the refining slag system. The dissolution rate of silicon oxide can be improved by reducing the viscosity of refining slag. Compared with the CaO-Al2O3-SiO2 slag system, the dissolution rate of silicon oxide was faster in the CaO-SiO2-CaF2 slag system at the same conditions. The refining experiments showed that increasing the basicity of CaO-Al2O3-SiO2 and CaO-SiO2-CaF2 refining slag systems was beneficial to the phosphorus removal of silicon sawing waste. The maximum removal ratio of phosphorus was 53.81% and 62.04% for the two refining slags, respectively.

Key words: Silicon sawing waste, CaO-SiO2-CaF2 refining slag, CaO-Al2O3-SiO2 refining slag, Oxide layer removal, Phosphorus removal by refining

摘要： 晶硅切割废硅粉是重要的新能源固废，切片过程电镀金刚线上磷的污染导致普通熔炼得到的再生硅磷含量高、品质差，无法满足有机硅行业对高品质原料的需求。本工作采用熔渣精炼一步去除晶硅切割废料的表面氧化层和非金属杂质磷元素，成功制备了有机用硅。首先使用石英砂模拟了硅粉表面氧化层的高温熔解行为，对比了CaO-Al2O3-SiO2和CaO-SiO2-CaF2两种渣系对二氧化硅的熔解效果，并考察了精炼时间(2~6 min)、精炼温度(1400, 1450和1500℃)下二氧化硅的熔解率。然后以晶硅切割废硅粉为原料，对比了两种精炼渣系对废硅粉的除磷效果，对氧化层和除磷结果进行了机理解析。结果表明，二氧化硅的熔解主要受精炼渣系的黏度影响，降低精炼渣的黏度能加快二氧化硅的熔解速率。相同条件下，二氧化硅在CaO-SiO2-CaF2渣系的熔解速率更快。精炼实验表明，提高CaO-Al2O3-SiO2和CaO-SiO2-CaF2精炼渣系的碱度有利于废硅粉中磷的去除，两种精炼渣的最大磷去除率分别为53.81%和62.04%。

关键词: 废硅粉, CaO-SiO2-CaF2渣系, CaO-Al2O3-SiO2渣系, 氧化层脱除, 精炼除磷