Sulfation of Partially Sulfided Calcium-Based Sorbents

Abstract

The solid waste materials from coal gasifiers that utilize limestone or dolomite for sulfur capture contain calcium sulfide, which is not stable and has the tendency to decompose when it contacts moisture in the air, releasing hydrogen sulfide to the atmosphere. The sulfide-containing wastes must be stabilized to produce a solid product that is environmentally acceptable for disposal. The reaction of partially sulfided calcium-based sorbents with oxygen for the production of stable calcium sulfate was investigated. Tests were conducted in an ambient-pressure quartz thermogravimetric analyzer and a 2-cm-diameter quartz fluidized-bed reactor to determine the effects of the sorbent type (limestone or dolomite), the sorbent particule size, extent of the sulfidation, and the sulfation temperature on the rate and extent of the sulfation reaction. Analyses of the sulfated samples indicate that the maximum level of sulfation is higher for dolomite compared to limestone. The maximum level of sulfation is also higher for sorbents with lower levels of sulfidation or smaller particle size. © 1991, American Chemical Society. All rights reserved.