Patent ID: 8470279

Claim:
A high-purity, silicon-containing product selected from the group consisting of silicon, silicon carbide, silicon nitride, alpha-silicon carbide and beta-silicon carbide, said high-purity, silicon-containing product being made by: providing a carbon-silica product derived from plant matter containing at least about 3 wt % silica that is leached with an aqueous sulfuric acid solution, the carbon-silica product consisting essentially of fixed carbon and silica bound to each other in a mole ratio of fixed carbon to silica that is appropriate to the stoichiometry of the intended product, said mole ratio being selectively adjustable to different levels between 1.37:1 and 5:1 without combustion and without adding high purity silica, said carbon-silica product containing less than 1000 ppm total mineral impurities in the group consisting of sodium, potassium, magnesium, calcium, manganese, iron, aluminum, boron and phosphorus; optionally devolatilizing the carbon-silica product; and carbothermally reacting the carbon-silica product or the optionally devolatilized carbon-silica product with a gas selected from the group consisting of hydrogen, argon, nitrogen, ultra-high purity nitrogen, nitrogen and hydrogen, and nitrogen and ammonia at a temperature between 1350° C. and 2200° C.; wherein said high-purity, silicon-containing product comprises a combined total of less than 1000 ppm of minerals or metals in the group consisting of sodium, potassium, magnesium, calcium, manganese, iron, aluminum, boron and phosphorus.