The present application provides a method, a equipment and a system for producing a silicon-containing products by using a silicon sludge which is produced by a diamond wire cutting silicon material. The method of the present application mainly utilizes a high oxide layer on the surface of a silicon waste particle produced during diamond wire cutting. The characteristics are such that the surface oxide disproportionates with adjacent internal elemental silicon to form silicon monoxide to be removed in a vapor to achieve a physical chemical reaction with a metal, a halogen gas, a hydrogen halide gas or hydrogen to form a high value-added silicon-containing products. The process realizes the large-scale, high-efficiency, energy-saving, continuous and low-cost complete recycling of diamond-wire cutting silicon waste.

The present application provides a method, a equipment and a system for producing a silicon-containing products by using a silicon sludge which is produced by a diamond wire cutting silicon material. The method of the present application mainly utilizes a high oxide layer on the surface of a silicon waste particle produced during diamond wire cutting. The characteristics are such that the surface oxide disproportionates with adjacent internal elemental silicon to form silicon monoxide to be removed in a vapor to achieve a physical chemical reaction with a metal, a halogen gas, a hydrogen halide gas or hydrogen to form a high value-added silicon-containing products. The process realizes the large-scale, high-efficiency, energy-saving, continuous and low-cost complete recycling of diamond-wire cutting silicon waste.

Methods of recycling silicon swarf into electronic grade polysilicon or metallurgical-grade silicon are described herein are described. In an example, a method includes cutting a silicon ingot and recovering silicon swarf having a first purity from the cutting process. The recovered silicon is purified in an upgraded metallurgical silicon process to produce electronic grade polysilicon particles having a second purity higher than the first purity. The upgraded metallurgical silicon process can include dissolving the recovered silicon particles in a molten aluminum metal smelt.

Methods of recycling silicon swarf into electronic grade polysilicon or metallurgical-grade silicon are described herein are described. In an example, a method includes cutting a silicon ingot and recovering silicon swarf having a first purity from the cutting process. The recovered silicon is purified in an upgraded metallurgical silicon process to produce electronic grade polysilicon particles having a second purity higher than the first purity. The upgraded metallurgical silicon process can include dissolving the recovered silicon particles in a molten aluminum metal smelt.

A crushed polycrystalline silicon lump is provided in which a surface metal concentration is 15.0 pptw or less and preferably 7.0 to 13.0 pptw, and in the surface metal concentration, a surface tungsten concentration is 0.9 pptw or less and preferably 0.40 to 0.85 pptw, and a surface cobalt concentration is 0.3 pptw or less and preferably 0.04 to 0.08 pptw.

A crushed polycrystalline silicon lump is provided in which a surface metal concentration is 15.0 pptw or less and preferably 7.0 to 13.0 pptw, and in the surface metal concentration, a surface tungsten concentration is 0.9 pptw or less and preferably 0.40 to 0.85 pptw, and a surface cobalt concentration is 0.3 pptw or less and preferably 0.04 to 0.08 pptw.

A method of removing surface carbon contamination from polycrystalline silicon comprises providing a polycrystalline silicon feed stream having surface carbon contamination, subjecting the polycrystalline silicon to a high velocity fluid selected from gas, gas/liquid mixtures, gas/solid mixtures and gas/solid/liquid mixtures to form a product stream comprising polycrystalline silicon having surface carbon in an amount of less than 200 parts per billion by weight based on weight of the polycrystalline silicon product and/or a reduction in surface carbon contamination of at least 20%. A system for conducting the method comprises an enclosure, a conveyer for moving a polycrystalline silicon feed stream through the enclosure, at least one stream of a high velocity fluid passing through outlets in the enclosure and directed at the feed stream, an ionizing source in the enclosure or integrated with the at least one stream of high velocity fluid, and an exhaust system for the enclosure.

A method of removing surface carbon contamination from polycrystalline silicon comprises providing a polycrystalline silicon feed stream having surface carbon contamination, subjecting the polycrystalline silicon to a high velocity fluid selected from gas, gas/liquid mixtures, gas/solid mixtures and gas/solid/liquid mixtures to form a product stream comprising polycrystalline silicon having surface carbon in an amount of less than 200 parts per billion by weight based on weight of the polycrystalline silicon product and/or a reduction in surface carbon contamination of at least 20%. A system for conducting the method comprises an enclosure, a conveyer for moving a polycrystalline silicon feed stream through the enclosure, at least one stream of a high velocity fluid passing through outlets in the enclosure and directed at the feed stream, an ionizing source in the enclosure or integrated with the at least one stream of high velocity fluid, and an exhaust system for the enclosure.

Metallurgical silicon containing impurities of carbon and/or carbon-containing compounds is classified and subsequently used selectively for chlorosilane production. The process comprises the steps of: a) determining the free carbon proportion which reacts with oxygen up to a temperature of 700 C., b) directing metallurgical silicon in which the free carbon proportion is 150 ppmw to a process for producing chlorosilanes and/or directing metallurgical silicon in which the free carbon proportion is >150 ppmw to a process for producing methylchlorosilanes.

As a result of the process, metallurgical silicon having a total carbon content of up to 2500 ppmw can be used for producing chlorosilanes.

Metallurgical silicon containing impurities of carbon and/or carbon-containing compounds is classified and subsequently used selectively for chlorosilane production. The process comprises the steps of: a) determining the free carbon proportion which reacts with oxygen up to a temperature of 700 C., b) directing metallurgical silicon in which the free carbon proportion is 150 ppmw to a process for producing chlorosilanes and/or directing metallurgical silicon in which the free carbon proportion is >150 ppmw to a process for producing methylchlorosilanes.

As a result of the process, metallurgical silicon having a total carbon content of up to 2500 ppmw can be used for producing chlorosilanes.