Production of Metallurgical Coke Utilizing Low Rank Coal Depolymerized by Wet Oxidation

Abstract

The authors have previously proposed to pretreat low rank coals with aqueous oxidant such as hydrogen peroxide in order to convert them by oxidative degradation reactions into thermoplastic coals suitable for coke making. The treatment with hydrogen peroxide aqueous solution at 60°C improved a brown coal’s thermoplasticity and high-strength cokes were successfully prepared from the dried treated coal. In this study effect of water content of the treated coal on its thermoplastic behavior was investigated. The water-containing treated coal melted and re-solidified at less than 200°C whereas the dried treated coal only softened at around this temperature. Apparent viscosity of the wet treated coal was dependent only on temperature and water content and could be lowered to as low as 2.5 × 10³ Pa s. The apparent viscosity of the treated coal containing a certain amount of water decreased with increasing temperature. The apparent viscosity at a certain temperature decreased with the increase of water content, reached a minimum value at around 40 wt% of water content on dry basis, and increased with the further increase of water content. As expected from the low apparent viscosity of the wet treated coal, the possibility was shown to utilize the treated coal as a binder for producing cokes from slightly- or non- coking coals.