Thermal crushing of alkali compounds in the removal of sulfur dioxides

Abstract

Alkali metal and alkaline earth metal carbonate compounds (in a variety of forms), including sodium ores of nahcolite and calcium ores of limestone, can be thermally comminuted or crushed. Size reduction is accomplished by a thermal treatment process called thermal crushing. The solids are subjected to a high temperature environment which causes a rapid temperature rise within the solid particles. This rapid temperature rise apparently results in a rapid generation of gases within the particle that exceeds the rate at which the gases can escape, thus resulting in a pressure buildup inside the solid particles. This causes the particles to explode or disintegrate into many smaller particles or powder. The resulting generation of small particles or powder by thermal crushing of thermally crushable carbonate compounds improves their application for removing reactive gaseous impurities, such as sulfur dioxide, NO.sub.x, etc., from a flue gas. To remove such gaseous impurities, the small particles or powder produced by thermal crushing are introduced into a flue gas when the flue gas is at a temperature up to 1,500.degree. F.