Method of coal upgrading

摘要

This invention relates to a method of converting a low-rank coal to produce a high-rank coal which has reduced hygroscopicity as well as increased heating value and lowered moisture content during and after transport or storage. The invention comprises the steps of heat-treating coal for dehydrating the coal and distilling off tar therefrom, vaporizing the tar, and coating the heat-treated coal surface with the tar vapor, whereby the coal surface is coated uniformly.