Mineral Wool Industry of the United States

Abstract

M / INERAL wool is a fibrous mineral material, resembling XV _ _ loose wool or cotton in appearance, which is made by blowing a jet of air or steam through molten slag. It consists of fine, interlaced fibers composed principally of silicates of calcium and aluminum together with other minor constituents. Because of the high percentage of dead air space in a given volume of wool, it is used extensively for sound and heat insulation. Mineral wool may be divided into three types according to the raw material from which it is made. These three types are rock wool, slag wool, and glass wool. Rock wool is made, in most cases, from natural siliceous limestones or calcareous shales. In some cases rock wool is made from limestone mixed with clay or shale in the proper proportions. Slag wool is made from blast furnace slag with or without the addition of limestone to temper the charge. Iron, copper, and lead slags are most commonly used in the production of slag wool. Glass wool is made from commercial glass batches. The principal materials which go into the glass batch are silica sand, lime, and soda ash.