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

摘要

Zinc and lead-bearing metallurgical dust (ZLMD) exhibit strong desulfuration ability due to their higher content of metal oxides, such as Fe_2O_3, 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 H_2S and a small part of COS, CS_2 are volatilized from briquette and react with ZnO and PbO to form ZnS and PbS at the earlier stage of combustion, and that O_2 oxidizes FeS_2 to form SO_2 at the later stage. The adsorption reaction of sulfur depends on the content of CaO. ZnO, ZnS and CaSO_4 are stable during the combustion process at temperatures lower than 1100℃. 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 H_2S/SO_2 released during briquette combustion processes.