Upgrading Indonesian Low-Rank Coal with an Oil Coating

ABSTRACT

In the present work, feasibility to upgrade Indonesian low-rank coal by oil coating was investigated. The low-rank coal (LRC) was upgraded by addition of bio tar, tallow, crude cashew nutshell liquid, refined cashew nutshell liquid, and waste lubricant. Two types of Indonesian low-rank coal samples were pulverized, mixed, dried, coated and briquetted by mixing of the aforementioned materials. Heat calorific values, crossing point temperatures, and moisture re-adsorption characteristics of raw and upgraded coal were evaluated. Heat calorific values of upgraded coals were significantly improved compared to raw coal. Upgraded coals showed a medium tendency to spontaneous combustion and resistance to moisture re-adsorption. Isothermal oxidation characteristics of raw and upgraded coal were assessed by means of the carbon-dioxide-formation rate in the exhaust gas. Upgraded coal showed less susceptibility to isothermal oxidation due to the suppression of active functional groups to oxygen in air by oil coating. Results of the study indicate that these additives are potential candidates for upgrading Indonesian LRC.

KEYWORDS:

• Low-rank coal
• upgrading
• spontaneous combustion
• isothermal oxidation

Funding

This work was supported by an Energy Efficiency & Resources Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20132020000170).

Additional information

Funding

This work was supported by an Energy Efficiency & Resources Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20132020000170).