Metallurgical silicon containing impurities of carbon and/or carbon-containing compounds is classified and subsequently used selectively for chlorosilane production. The process comprises the steps of:



a) determining the free carbon proportion which reacts with oxygen up to a temperature of 700° C.,
b) directing metallurgical silicon in which the free carbon proportion is ≤150 ppmw to a process for producing chlorosilanes and/or directing metallurgical silicon in which the free carbon proportion is >150 ppmw to a process for producing methylchlorosilanes.




As a result of the process, metallurgical silicon having a total carbon content of up to 2500 ppmw can be used for producing chlorosilanes.