Experimental study on liberation and separation of coking middlings

Abstrat : n order to make ful use of scarce coking coal resource,the experimental study on liberation and separation of the dense medium coking middlings from Qianjiaying Coal Preparation Plant was conducted in this paper.The teeter bed separator( TBS) was used for separation prediction of 1~ 0.25 mm size fraction.Whie the flotation separation performance of-0.25 mm size fraction was optimized by using column flotation and roughing-cleaning operation.The results showed that the final product of 1 ~ 0.25 mm size fraction wittld be obtained by TBS.However,the satisfactory result could not be obtained for the fine fraction using the conventional flotation machine.The wet screening test was carried out to identfy the reason for the high ash content of the concentrate,and the resultshowed that the water entrainmentof-0.045 mm size fraction was a major cause,which made the ash ofthe final product exceed the required.The results with SEM-EDS showed thatthere was much fine kaolinite slime coated on the clean coal surface.T he column fiotation and roughing-cleaning operation were conducted to lower the concentrate ash content and the results showed that entrainment decreased with alimited exvtent with the higher foam layer,but th final product of-0.25 mm fine fraction,11.91% ash content and 24.14% yield,could be obtained with roughing-cleaning operation.