Genesis of some tertiary Indian coals from the chemical composition of ash – a statistical approach: Part 1

Abstract

In the present investigation, 37 numbers of high sulphur tertiary coal samples from Meghalaya, India have been studied on the basis of proximate and ash analysis. Various statistical tools like Bivariant Analysis, Principal Component Analysis (PCA) and Hierarchical Clustering Analysis (HCA), and also the geochemical indicators were applied to determine the dominant detrital or authigenic affinity of the ash forming elements in these coals. The genetic interpretation of coal as well as the coal ash has been carried out based on chemical compositions of high temperature ash (HTA) by using Detrital/Authigenic Index. X-Ray Diffraction (XRD) analysis was also carried out to study the mineralogy of the studied coal ashes. Both statistical tools and geochemical indicators have confirmed the detrital nature of these coals as well as the ash forming elements.

Ash analyses of bio-coal briquettes produced using blended binder

“…The fouling factor (FF) of the bio-coal briquette ashes (0.44—0.55) were a little higher compared to that of raw coal (0.43). The FF results of the present study are similar to FF of < 0.45, which were obtained for Prajapara coal 41 and Meghalaya coal 42 that were reported to have a low fouling factor. The low FF indicates that the bio-coal briquette has low potential to fouling.…”

“…The presence of ZnO and CuO was very small in ppm. The presence of these oxides in the coal and bio-coal briquette has been reported in previous studies 39, [41][42][43] . The presence of these oxides in different ratios serves as indices for different coal ash behaviours such as slagging, fouling, and abrasion.…”

“…FT has been linked to flow changes in liquid and plastic phases. The FT of the raw coal and bio-coal briquettes do not exceed 1350 °C, whereas FT of > 1500 °C was reported for Meghalaya coal 42 . This shows that the raw coal is a lean grade type compared with Meghalaya coal, which was reported to be of higher grade (subbituminous).…”

“…These were further discussed in detail in the other subsection. The SiO 2 and Al 2 O 3 contents of the raw coal and bio-coal briquettes are within the acceptable range for the ash of fuel suitable for energy and metallurgical applications 39 , 42 . The SiO 2 and Al 2 O 3 variations showed that an increase in torrefied biomass within the bio-coal briquette composition had an abysmal effect on the ash.…”

“…The transformation of various oxides to other forms could pose a major setback leading to inefficient combustion process when bio-coal briquettes are in use. Identification of some other minerals by XRD only in a multi-component system such as the lean grade coal and bio-coal briquettes is difficult due to peak overlapping 42 . However, the presence of other mineral phases in form of oxides was visibly detected and quantified using XRF analysis.…”