A process for producing solar grade silicon from silica sand employs a plurality of plasma furnaces to perform a sequence of chemical reactions together with other process steps to produce solar grade silicon. The plasma furnace generates a stable dirty air, donutshaped plasma into which particulate matter can be introduced. The plasma in the first two stages is formed by gases from the chemical reactions and in the third from inert gasses. Cyclone separators are used to extract particulates from the plasma in an inert gas that prevents reverse reactions as the particular cools.

A process for producing solar grade silicon from silica sand employs a plurality of plasma furnaces to perform a sequence of chemical reactions together with other process steps to produce solar grade silicon. The plasma furnace generates a stable dirty air, donutshaped plasma into which particulate matter can be introduced. The plasma in the first two stages is formed by gases from the chemical reactions and in the third from inert gasses. Cyclone separators are used to extract particulates from the plasma in an inert gas that prevents reverse reactions as the particular cools.

Disclosed is a method for preparing an elemental material by reduction using monoatomic carbon, comprising: in a melt medium at a temperature of from 300° C. to 1500° C., cracking an organic carbon source into atomic carbon and dissolving the atomic carbon in the melt medium, allowing the atomic carbon to reduce an elemental precursor compound present in the melt medium by an oxidation-reduction reaction to generate an elemental material, and obtaining the elemental material by supersaturating and crystallizing. The method of the present invention can prepare the elemental materials with high quality by self-crystallization growth at a lower temperature and at a lower cost.

Disclosed is a method for preparing an elemental material by reduction using monoatomic carbon, comprising: in a melt medium at a temperature of from 300° C. to 1500° C., cracking an organic carbon source into atomic carbon and dissolving the atomic carbon in the melt medium, allowing the atomic carbon to reduce an elemental precursor compound present in the melt medium by an oxidation-reduction reaction to generate an elemental material, and obtaining the elemental material by supersaturating and crystallizing. The method of the present invention can prepare the elemental materials with high quality by self-crystallization growth at a lower temperature and at a lower cost.

A method for coating a silicon material can include mixing the silicon material with a coating reagent, and heating the mixture of the silicon material and the coating reagent to a treatment temperature for a treatment time. The silicon material can optionally include primary particles that are clustered into secondary particles. The resulting coating can optionally include carbon coating, graphite coating, or a polymeric coating.

A method for coating a silicon material can include mixing the silicon material with a coating reagent, and heating the mixture of the silicon material and the coating reagent to a treatment temperature for a treatment time. The silicon material can optionally include primary particles that are clustered into secondary particles. The resulting coating can optionally include carbon coating, graphite coating, or a polymeric coating.

A silicon material can include particles with a size between about 10 nanometers and 10 micrometers, where the particles can be porous or nonporous, and a coating disposed on the particles, wherein a thickness of the coating can be between about 1 nm and 1 μm. The coating can optionally include a carbon coating, graphite coating, or a polymeric coating.

An apparatus and a process for the production of high purity silicon from silica containing material such as quartz or quartzite, using a vacuum electric arc furnace, are disclosed.

An apparatus and a process for the production of high purity silicon from silica containing material such as quartz or quartzite, using a vacuum electric arc furnace, are disclosed.

Disclosed herein are embodiments of producing Si or SiO.sub.x from inexpensive silica sources. In some embodiments, plasma processing can be used to covert the silica sources to the silicon products. Unique morphologies can be formed in some embodiments. In some embodiments, reducing agents, catalysts, and/or salts can be used to provide advantageous properties.