(JP10265214-A)      Pure Si for use in solar cells is obtained from Si oxide by: reducing molten Si oxide with C; pouring and solidifying the resulting metallurgical grade Si in a mold; melting and refining; and purifying in a single solidification step. Preferably P is eliminated from the metallurgical grade Si by melting at sub-atmospheric pressure; B and C are eliminated using an acid gas; and O2 is eliminated by de-oxidation. The liquid Si is then solidified into a rod and Fe, Al, Ti and Ca are eliminated by zone melting.    ADVANTAGE -   the method allows impure Si products that are removed or cut off from the metallurgical grade material to be recycled.    (JP10324514-A)      Pure Si for use in solar cells is obtained from Si oxide by: reducing molten Si oxide with C; pouring and solidifying the resulting metallurgical grade Si in a mold; melting and refining; and purifying in a single solidification step. Preferably P is eliminated from the metallurgical grade Si by melting at sub-atmospheric pressure; B and C are eliminated using an acid gas; and O2 is eliminated by de-oxidation. The liquid Si is then solidified into a rod and Fe, Al, Ti and Ca are eliminated by zone melting.    ADVANTAGE -   the method allows impure Si products that are removed or cut off from the metallurgical grade material to be recycled.    (JP10324515-A)      Pure Si for use in solar cells is obtained from Si oxide by: reducing molten Si oxide with C; pouring and solidifying the resulting metallurgical grade Si in a mold; melting and refining; and purifying in a single solidification step. Preferably P is eliminated from the metallurgical grade Si by melting at sub-atmospheric pressure; B and C are eliminated using an acid gas; and O2 is eliminated by de-oxidation. The liquid Si is then solidified into a rod and Fe, Al, Ti and Ca are eliminated by zone melting.    ADVANTAGE -   the method allows impure Si products that are removed or cut off from the metallurgical grade material to be recycled.    (US6090361-A)      Pure Si for use in solar cells is obtained from Si oxide by: reducing molten Si oxide with C; pouring and solidifying the resulting metallurgical grade Si in a mold; melting and refining; and purifying in a single solidification step. Preferably P is eliminated from the metallurgical grade Si by melting at sub-atmospheric pressure; B and C are eliminated using an acid gas; and O2 is eliminated by de-oxidation. The liquid Si is then solidified into a rod and Fe, Al, Ti and Ca are eliminated by zone melting.    ADVANTAGE -   the method allows impure Si products that are removed or cut off from the metallurgical grade material to be recycled.