Distribution of mineral species in different coal seams of Talcher coalfield and its transformation behavior at varying temperatures

Amit Banerjee,R Das Biswas,Ashok Mohanty,S Chakravarty,K Chakravarty,P R Mishra,R Sahu

doi:10.1007/s40789-016-0127-0

Abstract

Mineral phase characterization and thorough understanding of its transformation behavior during combustion are imperative to know the potential utilization of coal in the thermal industries. The primary objective of this work is to analyze the quality of Indian Coals and obtain their mineral species-specific information at different depths. The samples were obtained from Talcher Coalfield, Odisha, India. Coal from four seam sections in the Talcher coalfield, India are mainly high ash coal (>50 %) and volatile matter deceases along with the seam depth. XRD results show that the major mineral phases present in the coal are quartz and kaolinite. Siderite, illite, and anatase were found in minor quantities. It has been observed that the clay minerals (kaolinite, silimanite, illite) decompose at higher temperature and traces of dolomite, mullite, hematite etc. are formed during the process of combustion. Among the four seams (M2, M12, M24 and M43) studied, ash of M43 has high Al2O3%, TiO2% and K2O% content and low SiO2%, CaO% and MgO% content. High acid-to-base ratios contributed to high ash fusion temperatures (IDT > 1500 °C) and low slagging potential of the coals studied. Relatively low fouling index (<0.3) was estimated for all the coal seams studied. Furthermore, thermodynamic modeling software, FactSage, have been used to envision the mineral phase transformations that take place between 800 and 1500 °C during coal combustion.

Highlights

Power plants in India predominantly use coal as the energy source for power generation
Investigations carried out on the coal samples of four different seams of a single borehole of the Tentuloi Block, Talcher coalfield, Orissa, India reveals that coals of all the four seams are similar in nature having high ash yields and low calorific values
Mineral matter composition of the coal ash for the four coal seams were similar with SiO2 and Al2O3 jointly accounting to a total of 92 %–94 % of ash mass

Summary

Introduction

Power plants in India predominantly use coal as the energy source for power generation. Knowledge of structural characteristics of minerals and mineral phase transformation that occurs during the process of combustion of coal is essential to understand the slagging and clinkering behavior. Vassilev et al (2005) have characterized mineral phase composition of composite samples from feed coals at Soma power station, Turkey. Mineral phases such as quartz, kaolinite, illite-muscovite, calcite, chlorite, plagioclase, pyrite etc. The process of phase transformation of mineral matter during coal combustion and gasification has been studied by some researchers. FactSage thermodynamic model was used to understand ash fusion behavior and to predict the phase transformation that occurs during the process of coal combustion. The transformation behavior of mineral matters during combustion of Chinese coal gangue at varied temperature was studied by Zhou et al (2012)

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