Abstract: Nitrogen and aluminum and fluxing agents (Al2O3, SiO2, CaO and MgO) are added to molten silicon to create an oxy-nitride slag that acts as a sink for dissolved boron and phosphorus. The nitrogen can be added by bubbling nitrogen gas through the molten silicon; the aluminum can be added as aluminum metal or as Al2O3. Normally, the silicon must initially be deoxidized to allow the boron and phosphorus refining reactions to occur. The process may be followed by oxidative refining, SiC settling, the Silgrain process and directional solidification to remove other impurities and produce silicon suitable for use in solar cells. In an alternative version of the process, the molten silicon is passed through a particulate bed formed of a nitrogen-containing compound and an aluminum-containing compound.

Abstract: Nitrogen and aluminum and fluxing agents (Al2O3, SiO2, CaO and MgO) are added to molten silicon to create an oxy-nitride slag that acts as a sink for dissolved boron and phosphorus. The nitrogen can be added by bubbling nitrogen gas through the molten silicon; the aluminum can be added as aluminum metal or as Al2O3. Normally, the silicon must initially be deoxidized to allow the boron and phosphorus refining reactions to occur. The process may be followed by oxidative refining, SiC settling, the Silgrain process and directional solidification to remove other impurities and produce silicon suitable for use in solar cells. In an alternative version of the process, the molten silicon is passed through a particulate bed formed of a nitrogen-containing compound and an aluminum-containing compound.

Abstract: The present invention relates to a method for the production of trichlorosilane by reaction of silicon with HCl gas at a temperature between 250° and 1100° C., and an absolute pressure of 0.5-30 atm in a fluidized bed reactor, in a stirred bed reactor or a solid bed reactor, where the silicon supplied to the reactor contains between 30 and 10.000 ppm chromium. The invention further relates to silicon for use in the production of trichlorosilane by reaction of silicon with HCl gas, containing between 30 and 10.000 ppm 10 chromium, the remaining except for normal impurities being silicon.