Improvements in or relating to methods of and means for water clarification and tailings filtration at coal washeries

摘要

794,353. Gravity-separation apparatus: filters. COAL INDUSTRY (PATENTS), Ltd. June 4, 1956 [June 2, 1955], No. 15849/55. Class 46. [Also in Group II] Fine coal is separated from dirt or shale in frothing cells 2, Fig. 1, from which water and tailings are discharged through a pipe 26 to the centre curtain 3 of a thickener tank 1, agents such as starch being added to assist the thickening process. Coarser tailings, which fall near the centre, are removed through a central outlet 5 and are pumped (13, 14) to a pipe 9 discharging into the headbox 8, Fig. 2, of a rotary vacuum filter drum 7, rotating anti-clockwise, on which they form a cake 12. Finer tailings, which tend to move outwards in the tank 1, are removed through a second outlet 6 situated at two-thirds of the radius from the tank centre and are pumped (15) through a pipe 16 delivering over a riffler tray 10, which discharges them on to the filter cake 12 via a deflector plate 11. The final filter cake is discharged into a shale bunker 17 while filtrate returns (assisted by a vacuum pump 18) through a pipe 19 to the tank 1. Tank overflow passes (20, 21) to a reservoir 22, whence it may be passed (23) back to the frothing cells 2. Overflow and bottom flow from the headbox 8 are returned to the tank 1 along pipes 24 and 25 respectively.