Boron Removal From Metallurgical-Grade Silicon Using CaO-SiO_2 Slag

The removal of boron impurity from metallurgical-grade silicon for solar cell application in slag system of CaO-SiO_2 is investigated.The experiments are conducted in an electromagnetic induction furnace which is used to heat. The distribution coefficient of boron(L_B)between slag and silicon phase is particularly examined in terms of the optical basicity of slag.With the increase of optical basicity,L_B increases to a local maximum value of 1.58 when the optical basicity is 0.71 after getting to the minimum value of 0.72 when the optical basicity is 0.56.In that above optical basicity of 0.71,L_B decrease sharply which indicates that increasing the basicity of slag is not always effective in boron removal from silicon.

磨矿方式对回收工业硅精炼渣中单质硅的影响

工业硅精炼渣(MGSRS,简称硅渣)中单质硅被渣紧紧包裹,且硅颗粒粒度分布不均,存在很多细小颗粒,在浮选过程中硅渣分离困难,导致单质硅的回收率较低。提出首先需要解决的是单质硅与渣的解离,研究了磨矿方式对硅渣解离的影响,进而研究了磨矿方式对浮选回收硅渣中单质硅的影响。结果表明,硅渣湿磨后进行浮选,单质硅的回收率为17.28%,远高于干磨的2.10%,这主要是由于湿法磨矿得到的硅渣颗粒平均粒度为21.07μm,且较干磨的颗粒均匀。微观形貌结果可见明显解离的单质硅颗粒,硅与渣分离的效果优于干磨。此外,由X射线光电子能谱(XPS)结果可知,湿磨中伴随着硅酸盐的水解过程,进一步提高了硅酸盐的亲水性。傅里叶变换红外光谱(FTIR)分析表明,湿磨后硅表面形成了悬挂的Si-H键,表面更加疏水,利于浮选。