Coal preparation practice

A critical factor in the utilization of coal is its quality. The main interest of the coal preparation engineer lies in process design, operation, and maintenance of the facilities required to produce an acceptable product from run-of-mine coal. Choice of a possible coal preparation method is usually made from a number of alternatives, and while the method eventually chosen is influenced by capital and profitability considerations, the nature of the raw coal to be treated is a major factor in the final selection. It is because of the latter aspect that coal preparation practice is tailored to the needs of each individual coal. This is of particular importance in the case of Canadian coal because of its extensive density. The premium quality required for the metallurgical coal market dictates that such coals be totally cleaned. Dense-medium cleaning processes are universally employed to treat coarse coal. Froth flotation is the preferred method of cleaning the fine coal. Coal preparation equipment in most Canadian installations is housed in buildings of the high-level design. Thermal drying of the clean coal product is achieved by using fluidized-bed thermal dryers, which are usually gasfirea. Conventional mechanical dewatering, including the use of centrifuges, is practiced priormore » to thermal drying. Since many coal producers did not expect raw coal to have such a high content of fines, the fines treatment facilities of most of the plants built in the early 1970's were not adequate.« less