Very large purity silicon for semiconductors is acquired using the Siemens method; the silicon is reacted to create trichlorosilane, and that is to start with purified by distillation, then reacted with purified hydrogen on high purity silicon rods at 1150 oC to generate high purity, polycrystalline silicon with hydrochloric acid https://dukerglasslinedpipe81479.pennywiki.com/4864379/tantalum_carbide_rod_secrets