Process upgradation and kinetic modeling of high-ash non-coking coal flotation using bio-based collector for enhanced clean coal recovery

The reduction of ash content, contributed by inorganic mineral matter,
and recovery of carbon values in a high ash non-coking coal was
studied in a laboratory-scale mechanical flotation cell using a biocollector
(PSO) derived from the pumpkin seeds for clean coal recovery.
Surface characterization of PSO (GCMS, FTIR) and untreated/PSOtreated
coal (contact angle, FTIR) indicated potential interaction
between PSO and the coal surface, enhancing its hydrophobicity,
while XRD analysis confirmed successful rejection of ash-forming
inorganic gangue minerals into tailings, signifying effective clean
coal separation from the gangue. The input parameters, such as
PSO dosage, frother MIBC dosage, and airflow rate (AFR), were
enhanced to attain best process responses, i.e. yield, ash, and fixed
carbon of the final clean coal. The use of PSO significantly reduced
the ash content of feed coal from 32% to as low as 9.86% in the final
clean coal while simultaneously increasing the fixed carbon content
from 35% to 61.15% and the gross calorific value from 4966 Kcal/Kg
to 6318 Kcal/kg. A clean coal product having high fixed carbon of
61.15% with 11.29% ash content and 70.14% yield was obtained at
PSO dosage of 10.73 Kg/t, MIBC dosage of 0.93 Kg/t and at AFR of
2.5lpm. The kinetic study revealed a high recovery of combustible
materials (~88%) and low ash recovery (~46%) at a flotation time of
480 seconds. Based on the kinetic model discrimination analysis, it
was found that the first-order fits well with the experimental data for
combustible and ash recovery. This study illustrates the efficacy of
pumpkin seed oil (PSO) as a potential bio-collector for the flotation of
non-coking coal, enhancing the coal quality by selectively reducing
mineral matter content and leading to substantial economic and
environmental advantages.