Theoretical and Experimental Study of Metal Capture during Incineration Process

Abstract

Experimental studies and thermodynamic equilibrium analysis were carried out to investigate the effects of operating conditions and input waste compositions on the adsorption of heavy metals (Cr, Pb, Zn, and Cd) on silica sand during incinceration processes. The experiments were performed with a pilot-scale fluidized bed incinerator, and the evaluated parameters include (1) sand bed temperature (500, 700, and 900°C); and (2) the addition of organic chloride (PVC), inorganic chlorides (NaCl and CaCl2), and sulfide (Na2S). The experimental and simulating results indicated that the addition of organic chloride (PVC) would increase the formation of volatile metallic chlorides, and decrease the adsorption efficiency of silica sand. On the other hand, the addition of inorganic chlorides (NaCl and CaCl2) worked differently, which increased the adsorption efficiency of silica sand. The addition of sulfide (Na2S) would increase the adsorption efficiencies of the four metals in silica sand because sulfide inhibited the formation of metallic chlorides. The hexavalent chromium content in the sand bed decreased for the addition of organic chloride (PVC), and increased for the addition of inorganic chlorides (NaCl and CaCl2).