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In this work leaching of low grade Indian coal was investigated. Coal samples of pre-treated and treated were characterized to quantify the quality of coal. An attempt has been made in this work to reduce the mineral matter from low grade coal of particle size 250 μm by leaching with H2SO4, HCl, Na2CO3 and NaOH solution as leaching agent at a temperature of 100°C for 3 h. It was found that the final ash content of treated coal was 22% from 38% of ash of feed raw coal by NaOH treatment alone compared to rest of the solvents. [ABSTRACT FROM AUTHOR]

In the present work an attempt have been made to upgrade the low grade Indian coal to high grade coal by using caustic (NaOH) leaching followed by acid (H 2 SO 4 ) treatment. The experimental works aimed at a selective attack on in situ MCL (Mahanadi Coal Limited) coal, Odisha, India with some fluxing agents like NaOH and H 2 SO 4 . The leaching experiments were carried out in a stainless steel batch reactor of 2.5 L capacity with controlled heating facility. Initially, the coal sample with −16+100 mesh particle size was leached with 50–150 g/L of NaOH solution at 100 °C for one hour and then subjected to leach further with 20% sulfuric acid. The maximum demineralization from the level of 26% ash with NaOH (100 g/L) leaching 27.5% is achieved and with combined chemical treatment method (100 g/L NaOH followed by 20% H 2 SO 4 ) was obtained 48% effectively. In addition, the results showed that the percent of demineralization improved adequately by decreasing the particle size also with rise of the leaching time and temperature. Coal characterization of raw and treated coal was done by Scanning Electron Microscopy (SEM)/Energy Dispersive Spectroscopy (EDS) analysis and also showed that the calorific value of coal was increased with increase the percent of demineralization of coal. [ABSTRACT FROM AUTHOR]