Mode of Occurrence of Trace Elements in Some Indian Coal

Abstract

Coal is the most important source of energy. In India about 70% of the total electricity generation is from coal-based thermal power plants; total estimated coal reserve is 255 billion tones. According to coal India vision-2025, its production in 2025 is projected to 1086 million tones against 384 million tones (2012-13). Coal contains most of the elements in the periodic table. Coal combustion is one of the important anthropogenic sources that release trace elements into the environment. Mobilization of elements is the major concern of ecosystems and health problems. Their release into surrounding environment largely depends on the modes of occurrence, which is defined as their distribution within coal. Mostly elements present in the mineral matter but some may be directly associated with the organic matter. In this paper an attempt has been made to understand the distribution of Ni, Mn, Cr, Cu, Pb and Zn in coal from east-central India (Mand-Raigarh coalfield), south India (Neyveli lignite) and north India (Rangit valley) representing distinct geological setting. Nickel and Cr are present in higher concentrations with respect to their world averages. Copper, Pb and Zn are associated mostly with sulphides and disulphides. Chromium preferably occurs with silicate minerals; Ni is nearly equally distributed in silicate, disulphides and sulphide minerals. Manganese primarily occurs as carbonates. Copper and Zn are mostly associated with organic part in lignite.