Jump to navigation Jump to search
- The treatment of coal to remove waste material such as: Dense (heavy) medium processes use a thick solution, usually a mixture of magnetite and water, to separate coal from impurities, such as sulfur, ash, and mercury, by gravity separation. Flotation processes treat fine-sized coal with an oil-based reagent that attracts air bubbles in a liquid medium; the coal floats to the surface as froth, leaving the refuse below. Hydraulic processes use currents of water to separate coal from impurities. Pneumatic processes use currents of air to separate coal from impurities.