真空精炼提纯工业硅除钙研究

Calcium Removal in Purifying Metallurgical-Grade Silicon by Vacuum Refining

钙是工业硅中的主要杂质元素之一,将其有效去除的方法之一是真空挥发技术。本文在真空挥发精炼除钙理论研究的基础上,开展了工业硅真空挥发精炼除钙的实验研究,考查了精炼时间、精炼温度等因素对钙去除效果的影响。研究结果表明,采用真空挥发精炼技术可以有效的去除工业硅中的杂质钙,可以将工业硅中杂质钙的含量从85×10-6降低到38×10-6,去除率为55.3%,且钙的去除率随着真空挥发精炼时间的延长和温度的升高而增加。

Removal of the calcium, a main impurity, from metallurgical-grade silicon（MC,-Si） by vacuum refining was physically modeled, theoretically calculated, and experimentally investigated. The effects of the evaporation conditions, in- eluding but not limited to the pressure,distillation temperature and distillation time, on the removal efficiency of calcium were evaluated. The results show that vacuum evaporation effectively removes calcium impurity from MG-Si, and that the distillation time and temperature significantly affect the separation efficiency of calcium. Distillated at 1823 K and a pres- sure of 10 Pa for 150 rain, calcium content in MG-Si was reduced to 38 parts per million weight（ppmw） ,a decrease from 85 × 10-6 to 38 × 10-6,and the removal efficiency is estimated to be 55.3% .In addition,higher distillation temperature and longer distillation time result in an increase of the seoaration rate of calcium.