Abstract:

Khánh Hòa Coal Colliery annually dumps to the mine temporary disposal storage hundred thousand tonnes of contaminated waste rocks. This type of waste rocks, which has an ash content of more than 60 % due to the contamination of interparting coals, is considered difficult to be treated. Characteristics of the contaminated waste rock shows that clean coals are relatively finely disseminated in rock. In order to recover clean coals from such a waste, the authors of the study have crushed the rock down to the sizes of - 3 mm and then have conducted experiments on fiuidized bed separation and froth flotation. Results of the study show that dean coals of less than 42 % ash (equivalent to fine coals 6B), recovery of over 58 % and rejects of more than 72 % ash can be obtained from of the size fractions 0.5 -1mm and 1-3 mm using fluidized bed separators while from the size fraction - 0.5 mm which was ground to the 95,98 % of passing size - 0.074 mm using froth flotation.