Thermodynamic behavior and morphology of impurities in metallurgical grade silicon in process of O_2 blowing

冶金级硅吹氧精炼过程中杂质的热力学行为和赋存状态(英文)

Gas blowing is a valid method to remove the impurities from metallurgical grade silicon（MG-Si） melt.The thermodynamic behavior of impurities Fe,Al,Ca,Ti,Cu,C,B and P in MG-Si was studied in the process of O2 blowing.The removal efficiencies of impurities in MG-Si were investigated using O2 blowing in ladle.It is found that the removal efficiencies are higher than 90% for Ca and Al and nearly 50% for B and Ti.The morphology of inclusions was analyzed and the phases Al3Ni,NiSi2 and Al3Ni were confirmed in MG-Si by X-ray diffraction.It was found that SiB4 exists in Si？B binary system.The chemical composition of inclusions in MG-Si before and after refining was analyzed by SEM-EDS.It is found that the amount of white inclusion reduces for the removal of most Al and Ca in the forms of molten slag inclusion and the contents of Fe,Ni and Mn in inclusion increase for their inertia in silicon melt with O2 blowing.

吹气精炼是一种从冶金级硅熔体中直接去除杂质的有效方法。研究了冶金级硅中杂质在吹氧过程中的热力学行为,通过与吹氧精炼前的比较,得到了精炼后硅中杂质的去除效率。研究发现,Ca、Al的去除率高于90%,B、Ti的去除率接近50%。通过XRD手段研究了冶金级硅中杂质的赋存状态,并确定了Al3Ni、NiSi2和Al3Ni等金属间化合物的存在。同时实验发现,除了Liquid、Diamond-Si、SiB3、SiB6、SiBn和β-B六个物相外,Si?B二元系中还存在SiB4相。通过SEM?EDS分析了吹O2精炼前、后冶金级硅中夹杂物的化学组成及形态变化。由于精炼过程中大多数Ca、Al以熔渣形式氧化而被去除,硅中白色夹杂的数量大幅度减少,而Fe、Ni、Mn等由于不能氧化而去除,在夹杂物中含量升高。