Geochemistry and petrology of coal and coal fly ash from a thermal power plant in India

The utilization of coal and its by-products (coal-combustion fly ash) is known for its detrimental effects on the environment including human health issues and global climate change. In this paper, the basic chemistry and geochemistry along with the petrographic studies of thermal plant's feed coal and their generated coal fly ashes is reported. The study also aims to predict the associated environmental concerns and quantification of REEs in the fly ash, which possibly might represent sources for recovery. The major minerals observed were quartz, kaolinite, haematite, illite, pyrite, and calcite in coal; and quartz, haematite, and pyrite in fly ash as confirmed by X-ray diffraction analysis. The results also demonstrated that Ce and Pr were exceptionally high in the both the samples C-1 (1075 ppm) and CF-2 (1248 ppm). The abundance of Nd is found to be high (479 ppm) in the fly ash samples. Hazardous elements were associated with nanominerals, including pyrite, anatase, and kaolinite as identified by using electron beam techniques. A multivariate statistical analysis of the elements including REEs in both coal and coal fly ash is also carried out to understand their mutual correlations.