A coal treatment process containing a coal-beneficiation process module. The module is implemented into the conventional coal treatment process of a coal-fired power plant after a first step of grinding the coal in a coal mill. The process module sequentially extracts chemical substances of non-combustible ash, water, mercury and oil that are found in coal before the coal is fired, so that present invention can produce valuable products and achieve a high quality cleaned powdered coal-char to burn in a furnace to thereby reduce pollution and increase the efficiency of energy production from the coal.