Fine coal evaluation by gravity methods

Lignite washing plants, in nature, process huge amount of run-off mine coal annually and produce signifi cant amount of tailings. Due to the certain characteristic of coal washing processes, in general, minus 0.5 mm size fraction containing valuable fi ner coals (mainly called slimes) can be discharged as tailings without effi cient further treatment. These tailings have also covered huge areas and lead to the several environment problems. In Turkey, the losses of recoverable amount of fi ne coal are estimated about 1 million t/yr. In the last decades, new technological processes and devices have been developed for coal fi nes benefi ciation such as Multi Gravity Separator (MGS), Falcon Concentrator, Kelsey Jigs and column fl otation. This investigation aims to recover of fi ne coals from tailings of two washery plants, Tunçbilek and Soma in Turkey. Spiral and MGS as gravitational methods were applied and optimum benefi ciation process fl ow sheet was developed based on MGS. Results indicate that two different quality clean coals having low ash content can be obtained. It is possible to reduce ash content of coal fi nes from between 55 - 68 to ten per cent (fi rst quality clean coal) and 25 per cent (second quality clean coal) by using gravity separation methods.