Upgradation of Low Grade Coal to High Quality Coal by Chemical Beneficiation Technique

Abstract

Low rank or grade coals (LGC) are widely distributed over the world. Coal plays a vital role in the global energy demand especially through power generation and it mitigates the energy poverty. The major challenges by the utility of coal as regarding to energy security, a risk of climate change, and increasing of the energy demands are the main portfolio to develop the advanced technology for coal beneficiation. The gradual depletion of high quality coal and cost effective which become a significant issue for power generation while the low grade coals were served as low cost fuel and as an alternative energy security issue. In current research the low grade coal (>35% ash) has been upgraded to higher grade (<10%) by chemical cleaning method. The low grade coal was selected from Mahanadi Coalfields Limited, Odisha, India. Each test was conducted of 50 g coal (250 μm particle size) with 40% NaOH at 100 °C for 3 h and followed with 20% of H2O2, H2SO4, HCl, and HF acids at similar conditions. The research study revealed that ash content (mineral matter) of coal is reduced to >70% by NaOH followed HF treatment as compared to other solvents. The greater liberation of mineral results increases the ash reduction from low grade coal because mineral associated in the coal matrix may formed elution by the leaching effect. The greater extent of demineralization was caused due to the high affinity of OH− and F− with minerals in the coal matrix. The characterization of pre and post treatment coal and coal ash was investigated by the FESEM, XRF and XRD analysis. Overall the current research study challenges the chemical cleaning of low grade coal has been efficient techniques for reducing the minerals to a certain limit.