Pilot-Scale Studies on Upgrading of an Indonesian Low-Rank Coal Using Palm Oil Residues

In the present study, a method was developed to upgrade low-rank coal using palm oil residues. The upgrading process consisted of pulverization, mixing, drying, coating, and briquetting. A palm oil residue (palm fatty acid distillate [PFAD]) was used to upgrade an Indonesian low-rank coal. Pores generated in the low-rank coal due to the evaporation of moisture were coated with the PFAD. The inhibitory effect of the PFAD was investigated by measuring the crossing-point temperature (CPT) of the upgraded coal. The amount of moisture re-adsorbed by the upgraded coal was compared to the raw coal with several methods. The CPT of the upgraded coal increased 10°C, and the moisture re-adsorption decreased by less than 60% compared with the raw coal. The upgraded coal briquettes were hydrophobic and had high compressive strength. This makes the upgraded coal sufficiently stable for long-term storage and long-distance transportation.