Coal cleaning waste or tailings material is a waste stream generated by the processing plant at the Coal Valley Mine. The waste material consists of impurities that have been removed from the coal in order to meet customer specifications. The plant produces up to 1.5 million tonnes of coal cleaning waste annually. The waste has been characterized as coarse reject material and fine reject material. The waste streams have traditionally been separated during the process with the coarse material being dry and used in the backfilling of mined areas and the fine material being pumped as a liquid to mined out pits for disposal.
The current disposal method has eliminated the use of filter presses and production of filter cake. The coarse (dry) reject material is screened from the process and hauled to active miring areas for disposal and reclamation. The fine (liquid) reject material from the process is pumped in slurry form to a mined out disposal area The current method of reclamation has eliminated the need to cap the tailings material with rock. The tailings material consolidates over time and after a period of dewatering, coversoil can be placed directly over the tailings material. This is carried out in winter when the upper part of the material is frozen.
Approximately 18 ha have been reclaimed using the new process. The various end land uses (forestry, wildlife, and wetlands) have been included in the reclaimed landscape. Some of the area has been reclaimed successfully without the use of coversoil. The geotechnical, water quality and reclamation aspects of this experimental procedure show encouraging results and will be discussed in more detail.