Mode of occurrence of trace elements in coal

Abstract

More than half of the country’s energy needs are fulfilled by coal. Besides power generation coal is also used in many other industries for production of cement, steel, etc. With the increasing usage of coal, the harmful impact of coal on environment cannot be neglected. Besides producing green house gases and other toxic fumes, the high metal content in coal pose a major threat to environment as well as life.
Trace elements are present in very low percentage in coal but their concentration increases manifold after coal combustion and utilization. Throughout the process of coal production as well as consumption, trace elements are released from coal. Their release into the surrounding atmosphere largely depends on the nature of their association with coal, also known as, their modes of occurrence. Basically, trace elements are present in the mineral matter but studies also show that some may be directly present in the organic matrix. Their
hazardous impact on environment emphasises more detailed study in this field. In this project efforts were made to study some trace elements namely - Ni, Mn, Cr, Cu, Zn and Pb in coal samples from Mand-Raigarh coalfield, Chhattisgarh; Rangit valley, Sikkim; and Neyveli
lignite, Tamil Nadu. Quartz and clay minerals were predominant in all the coal samples. Nickel and Cr are present in higher concentrations in all coal samples. Copper, Pb and Zn were associated with sulphides and disulphides. Chromium and Ni are organically associated
in Neyveli lignite. Primary mode of occurrence of Mn is concluded to be as carbonates.