RETENTION OF ARSENIC AND SELENIUM IN ACTIVATED CARBONS IN COAL COMBUSTION AND GASIFICATION FLUE GASES

摘要

In order to avoid problems from the emission of potentially toxic compounds of arsenic and selenium in flue gases from coal combustion and gasification processes, it is necessary to develop efficient gas cleaning systems capable of reducing their content in flue gases to below certain limits. Two activated carbons RBGH3 and RB3 were tested to capture arsenic and selenium species present in coal combustion and gasification atmospheres, in a laboratory scale reactor. RBGH3 was prepared by impregnating RB3 with sulphur and has proven good retention capacities for mercury compounds in gas phase. Arsenic and selenium compounds were retained in these carbons in different proportions, the efficiency of retention mainly depending on element speciation in the different atmospheres. The extent of arsenic and selenium retention in coal combustion and gasification environments is different. Arsenic retention in both atmospheres is similar. However, retention of selenium in a combustion atmosphere is negligible, whereas in a gasification atmosphere it can be higher than 50% wt.