A metallurgical route to solar-grade silicon

摘要: The aim of the process is to produce silicon for crystallization into ingots that can be sliced wafers processing photovoltaic cells. If potential purity realized, will also applicable ribbon pulling techniques where purification during negligible. consists several steps: selection and raw materials, carbothermic reduction silica, ladle treatment, casting, crushing, leaching, melting. leaching step crucial high purity, obtainable determined by solidification before leaching. most difficult specifications fulfill are low contents boron, phosphorus, carbon. Boron phosphorus excluded from but unavoidably saturate with carbon at temperature. During cooling precipitate as carbide crystals, which harmful in solar cost this depend strongly on scale production. It yet premature give exact figures, a some thousand tons per year, only few times ordinary metallurgical silicon.