Assessment of Potability of Minewater Pumped Out from Jharia Coalfield, India: An Integrated Approach Using Integrated Water Quality Index, Heavy Metal Pollution Index and Multivariate Statistics

The dense and industrialized populace in the mining areas of Jharia Coalfield (JCF) is plagued by a severe shortage of water supply. The unutilized pumped out coal minewater discharges may be utilized to cater to the increasing water demand of the region but it runs the risk of getting contaminated from domestic and industrial effluents. The current study aimed to assess the suitableness of augmenting underground minewater for potable purposes. Minewater samples collected from 15 locations (minewater treatment plants) across JCF for the hydrological year 2019-2020 were analysed to gain an insight on the physico-chemical characteristics of the minewater using an integrated approach of standard hydrochemical methods, Integrated Water Quality Index (IWQI), Heavy metal Pollution Index (HPI) and Multivariate Statistical Analysis. The integrated approach gives a holistic assessment of the minewater quality, overcoming the limitations of traditional water quality indices, to give a more accurate assessment. The analysis of minewater in the region identified Ca–Mg–HCO3 and Ca–Mg–Cl–SO4 as the two major water types. Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) of the minewater revealed the influence of lithogenic and anthropogenic processes in modulating the water chemistry of the region. This study could facilitate effective water quality management practices while also laying the foundation for augmenting minewater for potable purposes to meet increasing demands.

Detecting and Analyzing the Evolution of Subsidence Due to Coal Fires in Jharia Coalfield, India Using Sentinel-1 SAR Data

Public safety and socio-economic development of the Jharia coalfield (JCF) in India is critically dependent on precise monitoring and comprehensive understanding of coal fires, which have been burning underneath for more than a century. This study utilizes New-Small BAseline Subset (N-SBAS) technique to compute surface deformation time series for 2017–2020 to characterize the spatiotemporal dynamics of coal fires in JCF. The line-of-sight (LOS) surface deformation estimated from ascending and descending Sentinel-1 SAR data are subsequently decomposed to derive precise vertical subsidence estimates. The most prominent subsidence (~22 cm) is observed in Kusunda colliery. The subsidence regions also correspond well with the Landsat-8 based thermal anomaly map and field evidence. Subsequently, the vertical surface deformation time-series is analyzed to characterize temporal variations within the 9.5 km2 area of coal fires. Results reveal that nearly 10% of the coal fire area is newly formed, while 73% persisted throughout the study period. Vulnerability analyses performed in terms of the susceptibility of the population to land surface collapse demonstrate that Tisra, Chhatatanr, and Sijua are the most vulnerable towns. Our results provide critical information for developing early warning systems and remediation strategies.

Combustion characteristics of high ash Indian thermal, heat affected coal and their blends

Onsite mine fire generates large volumes of heat-affected coal in Jharia coalfields, India. Direct utilization of such heat-affected coal in thermal utilities is not feasible as such coal does not have the desirable volatile matter required for combustion. In the present work, experimental studies have been carried out to investigate the possible utilization of such heat-affected coal in thermal utilities by blending with other coal. Heat-affected coal (31% ash and 5300 kcal/kg GCV) collected from Jharia coalfield were blended with thermal coal (28% ash and 5650 kcal/kg GCV) in different ratios of 90:10, 80:20, 70:30 and 60:40 to identify the desirable blend ratio for burning of blended coal in thermal utilities. Burning characteristics of all the coals were carried out using TGA. Various combustion parameters such as ignition temperature, peak temperature, burnout temperature, ignition index, burnout index, combustion performance index, rate and heat intensity index of the combustion process and activation energy were evaluated to analyse the combustion process. Experimental and theoretical analysis shows the blend ratio of 90:10 can be used in place of only thermal coal in utilities to reduce the fuel cost.