Occurrences of valuable trace elements in Iranian coals as potential coal combustion byproducts

In Iran, coal as one of the primary energy resources mainly has just one customer (Iranian Steel Corporation); therefore, coal and production of its combustion have recently attracted much attention as promising alternative sources for valuable trace metals (VTM). Since there has been few principle exploration on occurrence modes of VTM for Iranian coal, this investigation assessed possible interactions between various coal conventional properties (proximate and ultimate analysis) and Y, Li, Ga, and V as VTM for Iranian coals. Statistical analyses indicated that on average, the contents of all these elements are higher than the general world coal ranges. Inter-correlation assessments showed that Ga and V in the samples are mainly associated with mineral matter (inorganic fracture of coal), e.g., mostly adsorbed by aluminosilicate (clay minerals) while Y and Li have a mixed organic and inorganic affinity. Strong interactions of Ga and V with inorganic fraction for samples with over 70% ash content released that host rocks of Iranian coal seams may also have the potential for the extraction of these two VTM. On the other hand, the mixed organic and inorganic affinity of Y and Li showed high possibility of their extraction from the coal combustion products. These results could be a critical key not only for geological and environmental information but also for developing possible procedures for their extraction.