Co-utilization of fly ash and flue gas scrubber sludge in the lime-sinter process

One of the most important technical issues of the 80's is the effective and economical disposal or utilization of solid wastes. In the case of coal wastes, the electric utility, the end user, the regulatory community, and the public share responsibility for taking action. Ash and flue gas desulfurization sludge produced annually in the United States alone total over 90 million tons and only a small fraction is utilized. The increased use of coal to generate electricity and of scrubbers to reduce SO/sub x/ emissions add to the urgency of developing sound waste management options. The lime-sinter process for the recovery of alumina from fly ash provides a means for co-utilization of the ash and sludge. The sludge is used as a mineralizer and partial replacement for the limestone. Extractable alumina-containing compounds are formed and high alumina yields result at moderate sintering temperatures. The process residue formed shows promise as a raw material for the manufacture of portland cement. 11 refs., 9 figs., 3 tabs.