• Clean Technology
• /
• v.19 no.4
• /
• pp.469-475
• /
• 2013

In this research, the stabilization characteristics of upgraded coal using palm oil residues were investigated. The Eco coal, which is the Indonesian low-rank coal, was used as a raw material. The low-rank coal was mixed with palm fatty acid distillate (PFAD), and then dried in a nitrogen atmosphere at $107^{\circ}C$. The trend of spontaneous combustion of upgraded coal was studied by measuring of crossing-point temperature (CPT), low temperature oxidation and moisture readsorption. The results of the CPT measuring and low temperature oxidation showed that the propensity of spontaneous combustion of the upgraded coal was improved compared to the dried coal. The moisture readsorption characteristics of the upgraded coal was also improved. The upgraded coal was stabilized through the surface coating with PFAD, and stability of upgraded coal was proportional to the content of PFAD.

• Korean Chemical Engineering Research
• /
• v.51 no.5
• /
• pp.609-614
• /
• 2013

This study investigated the spontaneous combustion behavior of solvent-treated low rank coals. Indonesian lignite (a KBB and SM coal) and sub-bituminous (a Roto coal) were mixed with non-polar 1-methyl naphthalene (1MN) either by mechanical agitation or ultrasonication. The property change associated with 1MN treatment was then analyzed using proximate analysis, calorific value analysis, Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy and moisture re-adsorption test. Susceptibility to spontaneous combustion was evaluated using crossingpoint temperature (CPT) measurement along with gas analysis by GC. A FT-IR profile showed that oxygen functional groups and C-H bonding became weaker when treated by 1 MN. XPS results also indicated a decrease of the oxygen groups (C-O-, C=O and COO-). Increased hydrophobicity was found in the 1MN treated coals during moisture readsorption test. A CPT of the treated coals was ${\sim}20^{\circ}C$ higher than that of the corresponding raw coals and the ultrasonication was more effective way to enhance the stability against spontaneous combustion than the agitation. In the gas analysis less CO and $CO_2$ were emitted from 1MN treated coals, also indicating inhibition of pyrophoric behavior. The surface functional groups participating in the oxidation reaction seemed to be removed by the ultrasonication more effectively than by the simple mechanical agitation.