Some mines are fortunate in that the product as mined is suitable for use with no other treatment. Such mines would usually only have a stockpile arrangement somewhere in the transport system between the mine and the user, most frequently at or close to the mine.
However most mines produce a coal which requires some improvement or benefication before use and this involves the provision of a Coal Preparation Plant.
Coal preparation is a specialisation in the field of minerals technology.
All coal contains some non-carbonaceous mineral matter both within the coal itself and added during the mining process (often unintentionally) where roof or floor is cut or breaks and mixes with the cut coal. This mineral matter affects the properties of the coal and becomes ash when the coal is burnt, a waste product to be disposed of. It is therefore often desirable to remove at least a portion of this material prior to end use.
Coal preparation plants usually use a number of processes taking advantage of the difference in density between coal and the mineral matter to separate the two (e.g. dense medium baths, froth flotation, cyclones).
Other processes involved in the preparation plant include stockpiling and recovery, dewatering, disposal of waste ("coal wash") and frequently transport to customer or to port for export.