Vassileva, CG; Daher, DF; Vassilev, SV
The chemical and phase-mineral composition, as well as thermal behavior of mazut fly ash (MFA) and slag (MS) generated from a Syrian power plant were studied. The data show that the major elements (> 1%) in MFA are Fe > Si > Al > 5> Ca > V > Mg; the minor elements (0.1-1%) include Zn > Na > Ni > Ti > K> P > Mn > Mo; while the other 20 elements studied are trace elements (< 0.1%). In contrast, the major elements in MS are V > Ni > Fe > Na > S; the minor elements include Si > Al > Ca > Zn > Cr > Mg; whereas the other 13 elements investigated are trace elements. The major minerals and phases identified in MFA and MS samples are glass, char, kaolinite, jarosite and pyracmonite; the minor minerals include quartz, magnetite and hematite; while the accessory minerals are plagioclase, K feldspar, illite + muscovite, chlorite, anhydrite, V oxides and Ni oxide. It was found that elements such as V > Mo > Ni > Zn > Ag > S in MFA and Ni > V > Zn > Mo > S > Co > Cr in MS have contents which are orders of magnitude greater than the Clarke values for coal ashes. Such element enrichments could be of great industrial interest for their recovery. On the other hand, a number of toxic and potentially toxic elements (Ag, Cd, Co, Cr, Mo, Ni, Pb, S, V and Zn) have high concentrations in MFA and MS and they could contaminate soils, waters, air and plants during the transport, storage, processing and/or utilization of these products. It was also highlighted that a clarification of the modes of element occurrence (minerals and phases) in MFA and MS is required in respect to utilization and element extractions from these combustion wastes.