Treating waste sludge contg. calcium sulphite and sulphate - includes calcining part of dewatered sludge and adding to remainder for disposal

摘要

Inorganic waste sludge contg. CaSO4 and/or CaSO3 and 30 wt% CaSO3 is hardened by partially dewatering the sludge, withdrawing part (1-90 wt %) of the thickened sludge which is then calcined at 250-650 degrees C. After withdrawing more thickened sludge (10-99 wt % solids) the remaining partially dewatered sludge is mixed with the calcined portion. Used for treating the aq. sludge from an alkaline desulphurising unit in a combustion plant. The proess eliminates the step of oxidising the sludge in the scrubber with metal oxide catalysts and a stabilised prod. is formed which is used as a landfill or a commercial prod.