Production of metallurgical coke utilizing low-rank coals upgraded by mild solvent treatment

Abstract

Steel industries need to increase the use of low-rank coals in coke making since coking coals have been depleting and the price of coking coal has been increasing. In this study we propose to pretreat low-rank coals in non-polar solvent such as 1-methylnaphthalene below 400°C for converting them to a substitute for coking coals. The proposed method was found to be effective in deoxygenating low-rank coals significantly while suppressing cross-linking or polymerization reactions which often accompany deoxygenation reactions. The amount of low-molecular-weight compounds formed in the solvent-treated coals was comparable to that existing in coking coals. Coking tests utilizing the solvent-treated coals suggested that the solvent-treated coals can be substitutes for slightly-coking coals in coke making process.