Abstract: A method for recovering or producing silicon, that can recover or produce silicon using cutting scraps containing silicon carbide abrasive grains and silicon as raw materials without separating those is provided. The present invention is a method for recovering or producing silicon from cutting scraps containing silicon carbide, which are produced during a cutting or grinding of silicon ingots or silicon wafers, wherein the method comprises producing silicon by heating the cutting scraps containing silicon carbide, and a silica raw material.

Abstract: A carbon black aggregate having a surface hardness of at least 70 g and having a covering.

Abstract: A method for producing carbon black by means of a horizontal carbon black production furnace having a first reaction zone in which a mixture of an oxygen-containing gas and a fuel is burned to form a high temperature gas stream, a second reaction zone in which a hydrocarbon feedstock is supplied and reacted with the high temperature gas stream formed in the first reaction zone, and a third reaction zone in which quenching water is sprayed into the gas mixture from the second reaction zone to terminate the reaction, wherein the second reaction zone is constructed to have a hollow cylindrical structure with at least two cylindrical sections having different inner diameters connected to one another and the hydrocarbon feedstock is divided for supply so that it is supplied to at least two locations including an upstream cylindrical section to which the hydrocarbon feedstock is first supplied and a cylindrical section located downstream thereof and so that the flow velocities of gases passing through the respectiv