Separation of mixtures of bituminous coal and lower rank coal by

Abstract

Method for separating a mixture of bituminous coal and a lower rank coal such as subbituminous, lignite, and mixtures thereof, comprising contacting the coal mixture with an effective amount of an aqueous chemical comminuting solution for a sufficient time to selectively comminute a substantial portion of one of the ranks of coal in the mixture. Thereafter, the comminuted coal and noncomminuted coal of different rank is separated from the chemical comminuting solution. The smaller comminuted coal particles of one rank are then separated from the larger noncomminuted coal of the other rank by screening. Substantially anhydrous methanol or an aqueous methanol solution is used to selectively comminute the bituminous rank coal whereas an aqueous alkaline solution, preferably aqueous sodium hydroxide, is used to selectively comminute the lower rank coal.