THE EFFECT OF OPERATING-CONDITIONS ON THE CAPTURE OF METALS WITH LIMESTONE DURING INCINERATION

The objective of this work was to experimentally study the effect of d ifferent operating conditions on sorbent (limestone) to capture metals and the formation of hexavalent chromium during fluidized bed inciner ation of wastes containing Pb, Cd, Cu, and Cr. The operating parameter s evaluated included: 1) addition of organic chloride (PVC); 2) additi on of inorganic chloride (NaCl); 3) addition of sulfide (Na2S); 4) siz e of sorbent; and, 5) air factor. The experiments were carried out in a pilot scale fluidized bed incinerator with air pollution control dev ices of two consecutive cyclones and a wet scrubber. Experimental resu lts indicated that limestone could effectively capture most heavy meta ls Pb, Cr, and Cd in the sand bed. The addition of organic chloride (P VC) and inorganic chloride (NaCl) in feedstock caused different conseq uences. The former decreased the adsorption efficiency, while the latt er increased the adsorption efficiency of limestone in the sand bed. M oreover, the presence of sulfide (Nr(2)S) was helpful in controlling m etals during incineration. Little hexavalent chromium is formed during incineration, but the presence of organic chloride PVC produced more Cr(VI) than inorganic chloride NaCl. Copyright (C) 1996 Elsevier Scien ce Ltd