Si-Cu合金精炼与造渣精炼去除冶金级硅中金属杂质

Removal of metallic impurities from metallurgical grade silicon by combining Si-Cu alloy refining with slag refining

采用Si-Cu合金精炼与CaO-SiO2-CaCl2造渣精炼相结合的方法对冶金级硅进行精炼,通过多种分析方法考察了合金造渣过程、渣剂添加剂和合金成分对金属杂质Fe、Al和Ca去除效果的影响.结果表明,提高Si-Cu合金中Cu的质量分数可以有效增加Cu3Si相在Si中的含量,造渣精炼过程会影响Si-Cu合金的相转变,造渣后金属杂质Fe和Ca聚集在Si-Cu合金的Cu3Si相中.在渣剂中添加CaCl2助溶剂可降低渣剂黏度以促进传质过程,从而有效提高金属杂质Fe、Al和Ca的去除率.此外,随着Si-Cu合金中Cu质量分数的增加,造渣后合金相中Cu的析出现象明显,Fe的去除率上升,Ca的去除率下降,而Al的去除率不变.当Si-30%Cu合金与CaO-SiO2-CaCl2(质量比9∶9∶2)渣剂进行精炼后,Fe、Al和Ca的去除率分别为68%,94%和86%.

A combined process of Si-Cu alloy refining and CaO-SiO 2 -CaCl 2 slag refining was used to remove metallic impurities,Fe,Al and Ca,from metallurgical grade silicon (MG-Si).Effects of refining procedure,slag addition,and alloy composition on the removal efficiency were investigated using several methods.It was found that the content of the Cu 3 Si phase in the Cu-alloyed MG-Si increased when the mass fraction of Cu increased.The slag refining would affect the phase transformation of the Si-Cu alloy,and impurities,Fe and Ca,were found to concentrate in the Cu 3 Si phase after slag refining.The addition of CaCl 2 facilitated the mass transfer process by decreasing the viscosity of the slag,thus enhancing the removal efficiency of impurities,Fe,Al and Ca.With the mass fraction of Cu increasing,more Cu was precipitated after slag refining, the removal efficiency of Fe and Ca increased and reduced,respectively,while that of Al was unchanged.When Si-30%Cu alloy was refined with CaO-SiO 2 -CaCl 2 (9∶9∶2, by mass) slag,the removal efficiencies of Fe,Al and Ca were 68%,94%,and 86%,respectively.