Provided are silicon fine particles that are effectively prevented from being oxidized and have a crystallite diameter close to that of an amorphous substance. The silicon fine particles of the present invention have an average diameter of primary particles of 30 to 900 nm, a crystallite diameter of less than 10 nm, a chlorine concentration of 1 to 10% by mass, and a ratio (C.sub.o/S) of an oxygen concentration (C.sub.o: % by mass) to a specific surface area (S: m.sup.2/g) of less than 0.05. The method for producing silicon fine particles of the present invention includes: heating a gas containing trichlorosilane to a temperature of 600 to 950° C. in a reactor and thermally decomposing the trichlorosilane to produce a silicon fine particle precursor containing chlorine, then collecting the silicon fine particle precursor, and then heating and dechlorinating the collected silicon fine particle precursor at a temperature of 750 to 900° C. under supply of an inert gas or under reduced pressure.

Provided are silicon fine particles that are effectively prevented from being oxidized and have a crystallite diameter close to that of an amorphous substance. The silicon fine particles of the present invention have an average diameter of primary particles of 30 to 900 nm, a crystallite diameter of less than 10 nm, a chlorine concentration of 1 to 10% by mass, and a ratio (C.sub.o/S) of an oxygen concentration (C.sub.o: % by mass) to a specific surface area (S: m.sup.2/g) of less than 0.05. The method for producing silicon fine particles of the present invention includes: heating a gas containing trichlorosilane to a temperature of 600 to 950° C. in a reactor and thermally decomposing the trichlorosilane to produce a silicon fine particle precursor containing chlorine, then collecting the silicon fine particle precursor, and then heating and dechlorinating the collected silicon fine particle precursor at a temperature of 750 to 900° C. under supply of an inert gas or under reduced pressure.

The invention relates to a method for the production of high-purity elementary silicon from a starting material containing silicon dioxide, which includes the steps of: a) thermal pre-purification of the starting material, wherein impurities from the group consisting of boron and phosphorus are separated essentially completely and a pre-purified silicon dioxide is obtained; b) reduction of the pre-purified silicon dioxide to elementary silicon; and c) removal of impurities remaining in the pre-purified silicon dioxide after step a) during and/or after step b).

The invention relates to a method for the production of high-purity elementary silicon from a starting material containing silicon dioxide, which includes the steps of: a) thermal pre-purification of the starting material, wherein impurities from the group consisting of boron and phosphorus are separated essentially completely and a pre-purified silicon dioxide is obtained; b) reduction of the pre-purified silicon dioxide to elementary silicon; and c) removal of impurities remaining in the pre-purified silicon dioxide after step a) during and/or after step b).

A treatment method for purifying silicon microparticles contained in waste resulting from the cutting of ingots with a diamond wire comprises: a) providing a contaminated slurry, resulting from the waste, formed by an aqueous mixture comprising the silicon microparticles, organic species and metal contaminants; b) adding a dilute hydrogen peroxide solution to the contaminated slurry, in order to form a first mixture, and stirring the first mixture; c) solid/liquid separation of the first mixture in order to obtain, on the one hand, a first purified slurry and, on the other hand, a first liquid loaded with organic species and metal contaminants.

A treatment method for purifying silicon microparticles contained in waste resulting from the cutting of ingots with a diamond wire comprises: a) providing a contaminated slurry, resulting from the waste, formed by an aqueous mixture comprising the silicon microparticles, organic species and metal contaminants; b) adding a dilute hydrogen peroxide solution to the contaminated slurry, in order to form a first mixture, and stirring the first mixture; c) solid/liquid separation of the first mixture in order to obtain, on the one hand, a first purified slurry and, on the other hand, a first liquid loaded with organic species and metal contaminants.

A carbon negative clean fuel production system includes: a main platform; a heat collection device for capturing heat from a hydrothermal emissions from a hydrothermal vent on a floor of an ocean; a heat-driven electric generator; a heat distribution system including a heat absorbing material and a heat transporting pipe; anchor platforms tethered to the main platform; a mineral separator; a seawater filtration unit; a water splitting device; a sand refinery machine; a carbon removal system; and a chemical production system for producing hydrides, halides and silane. Also disclosed is a method for carbon negative clean fuel production, including: capturing heat; producing electric energy; separating minerals; filtering seawater; splitting water; refining sand; removing carbon dioxide; and producing hydrides, halides, and silane.

A carbon negative clean fuel production system includes: a main platform; a heat collection device for capturing heat from a hydrothermal emissions from a hydrothermal vent on a floor of an ocean; a heat-driven electric generator; a heat distribution system including a heat absorbing material and a heat transporting pipe; anchor platforms tethered to the main platform; a mineral separator; a seawater filtration unit; a water splitting device; a sand refinery machine; a carbon removal system; and a chemical production system for producing hydrides, halides and silane. Also disclosed is a method for carbon negative clean fuel production, including: capturing heat; producing electric energy; separating minerals; filtering seawater; splitting water; refining sand; removing carbon dioxide; and producing hydrides, halides, and silane.

Provided are processes to form microporous silicon useful as an active material in an electrode of an electrochemical cell the processes including subjecting a mixture of silicon oxide and a metal reducing agent, optionally aluminum, to mechanical milling to form mechanically activated silicon oxide/aluminum, thermally treating the silicon oxide/aluminum to reduce the silicon oxide and form Si/Al.sub.2O.sub.3, and removing at least a portion of the alumina from the Si to form a microporous silicon. The resulting electrochemically active microporous silicon is also provided with residual alumina present at 15% by weight or less that demonstrates excellent cycle life and safety.

Provided are processes to form microporous silicon useful as an active material in an electrode of an electrochemical cell the processes including subjecting a mixture of silicon oxide and a metal reducing agent, optionally aluminum, to mechanical milling to form mechanically activated silicon oxide/aluminum, thermally treating the silicon oxide/aluminum to reduce the silicon oxide and form Si/Al.sub.2O.sub.3, and removing at least a portion of the alumina from the Si to form a microporous silicon. The resulting electrochemically active microporous silicon is also provided with residual alumina present at 15% by weight or less that demonstrates excellent cycle life and safety.