Patent ID: 8273176

Claim:
A process for obtaining silicon crystals from silicon powder, comprising: contacting silicon powder with a solvent metal, to provide a mixture containing silicon, wherein the solvent metal is selected from the group consisting of silicon, molten silicon, copper, tin, zinc, antimony, silver, bismuth, aluminum, cadmium, gallium, indium, magnesium, lead, an alloy thereof, and combinations thereof; melting the silicon under submersion by feeding the silicon powder into a vortex within the solvent metal using a rotary degasser, rotary furnace, molten metal pump or induction currents, to provide a first molten liquid; contacting the first molten liquid with a first gas, to provide dross and a second molten liquid, wherein the first gas comprises water vapor (H 2 O), and at least one of oxygen (O 2 ), nitrogen (N 2 ), helium (He), argon (Ar), hydrogen (H 2 ), carbon dioxide (CO 2 ), and carbon monoxide (CO); separating the dross and the second molten liquid; cooling the second molten liquid approximately homogenously to provide fractional crystallization to form first silicon crystals and a first mother liquid; separating the first silicon crystals and the first mother liquid; melting the first silicon crystals, to provide a first molten bath; contacting the first molten bath with a second gas, wherein the second gas comprises oxygen (O 2 ), water vapor (H 2 O), hydrogen (H 2 ), an inert gas, or a combination thereof; directionally solidifying the first molten bath, to provide second silicon crystals; heating the second silicon crystals, to provide a second molten bath; and directionally solidifying the second molten bath to provide purified silicon; wherein the purified silicon that is obtained from the last step of the process is used to make solar cells.