Robert Dennis Chaney

US Patent:

41728831, Oct 30, 1979

Filed:

Jun 23, 1978

Appl. No.:

5/918537

Inventors:

Robert A. Administrator of the National Aeronautics and Space Frosch
William M. Ingle - Phoenix AZ
Stephen W. Thompson - Phoenix AZ
Robert E. Chaney - Scottsdale AZ

International Classification:

C01B 3302

US Classification:

423348

Abstract:

A method wherein a quartz tube is charged with chunks of metallurgical grade silicon and/or a mixture of such chunks and high purity quartz sand, and impurities from a class including aluminum, boron, and the like, as well as certain transition metals including nickel, iron, manganese and the like. The tube is then evacuated and heated to a temperature within a range of 800. degree. C. to 1400. degree. C. , whereupon a stream of gas comprising a reactant, such as silicon tetrafluoride, continuously is delivered at low pressures through the charge for causing a metathetical reaction of impurities of the silicon and the reactant to occur for forming a volatile halide and leaving a residue of silicon of an improved purity. Additionally, the reactant may include carbon monoxide gas, whereby impurites such as iron and nickel react therewith to form volatile carbonyls.