The recovery of silicon from the waste industrial silicon slag is urgent for the cleaner production of silicon industry. The feasibility and optimization of recovering and purifying the metallic silicon from silicon slag are investigated by a united technology of combining electromagnetic separation and slag treatment. The physicochemical purification mechanism of silicon from slag was put forward. A calcium silicate slag reagent containing chlorine was added to the raw materials, which displays greatly role on separation and purification of metallic silicon. The optimized experimental conditions of melting time 60 min and heating power 15 kW were obtained. The recovery rate of silicon from waste silicon slag reaches about 96% and the removal rate of Al and Fe reaches 98.1% and 81.5%, respectively. The industrial tests on a scale of several thousand kilograms treatment capacity for silicon slag display that most impurities can be removed into slag phase and the output rate of silicon reaches over 81%.The united electromagnetic separation and slag treatment technology is expected to be used on a large scale in production.

从工业废硅渣中回收硅对于清洁工业生产来说是迫在眉睫的。采用电磁分离与炉渣处理相结合的联合技术，研究了从硅渣中回​​收提纯金属硅的可行性和优化方法。提出了从炉渣中提纯硅的理化机理。原料中加入了含氯的硅酸钙炉渣试剂，对金属硅的分离提纯起到了很大的作用。获得了熔化时间为60 min，加热功率为15 kW的优化实验条件。废硅渣中硅的回收率达到96％左右，铝和铁的去除率分别达到98.1％和81.5％。