An investigation on demineralization induced modifications in the macromolecular structure and its influence on the thermal behavior of coking and non-coking coal

Eight coking and non-coking coals have been studied by Wide Angle X-ray Scattering (WAXS), Fourier Transform Infrared Spectroscopy (FTIR), and TG/DTG (Thermogravimetry/Derivative Thermogravimetry) - DSC (Differential Scanning Calorimeter). The FTIR study shows that the demineralization treatment significantly influences -OH, aliphatic (-CH 3 , -CH 2 ), aromatic (C = O), and aromatic nucleus (C = C) functional groups of the raw coals. The structural parameters like interlayer spacing (d 002 ), crystallite size ( L c ), lateral size ( L a ), aromaticity ( f a ) XRD, and rank ( I 26 /I 20 ) are determined from WAXS. The WAXS results of demineralized coal show that d 002 (range 3.75-3.51 A) decreases, but ( f a ) XRD (range 0.69-0.88) increases with the increase of elemental carbon percentage ( C daf ) and rank of coals. The combustion and kinetic parameters of these coals have been evaluated by TG/DTG - DSC analysis. The ignition temperature (T i ), DTG T peak , DSC T peak, and burnout temperature (T b ) vary in the range of 338-410 degrees C, 475-551 degrees C, 490-555 degrees C, and 579-641 degrees C, respectively for demineralized coals however variations of these parameters for raw coals are 345-361 degrees C, 462-621 degrees C, 467-631 degrees C, and 560-675 degrees C, respectively. The TG/DTG - DSC and FTIR results show that demineralization influences the thermal behaviors and functional groups vis-a-vis structural moieties of coals.

Automated summary

Eight coking and non-coking coals were studied using WAXS, FTIR, and TG/DTG-DSC techniques. Demineralization treatment had a significant influence on the functional groups and structural parameters of the coals. The combustion and kinetic parameters were also evaluated. Results showed that demineralization affected the thermal behavior and functional groups of the coals.