Study on utilizing zinc and lead-bearing metallurgical dust as sulfur absorbent during briquette combustion

Zinc and lead-bearing metallurgical dust (ZLMD) exhibit strong desulfuration ability due to their higher content of metal oxides, such as Fe2O3, ZnO, PbO and CaO. In present work, their performances as a sulfur absorbent used in the combustion process of briquette, which is made up of coal and ZLMD, are investigated. Experimental results show that a large part of H2S and a small part of COS, CS2 are volatilized from briquette and react with ZnO and PbO to form ZnS and PbS at the earlier stage of combustion, and that O2 oxidizes FeS2 to form SO2 at the later stage. The adsorption reaction of sulfur depends on the content of CaO. ZnO, ZnS and CaSO4 are stable during the combustion process at temperatures lower than 1100 °C. When the weight percent of ZLMD in the briquette is kept at around 2.5%, and sulfur in coal at around 2.1%, the absorption efficiency of sulfur can reach 90%. These results suggest that utilizing ZLMD as a sulfur absorbent in the combustion process of briquette is a cheap and highly efficient method to treat both ZLMD and toxic emission such as H2S/SO2 released during briquette combustion processes.