. Transactions of the Institution of Mining Engineers . c-ticable, it was substituted by a mechanicalintermittent evacuation, producing in thetrough over the slot a state of continuity of the bed of shale, thusallowing no coal to fall down with the shale through the slots. The slot,however, was replaced by a more spacious chamber. If this chamber be of sufficient capacity, it is found that the flap-valve can evacuate, at each oscillation, a certain quantity of shale,and that this action does not lower the upper surface of the bed of apparatus shown in Fig. 11 has therefore been evolv
. Transactions of the Institution of Mining Engineers . c-ticable, it was substituted by a mechanicalintermittent evacuation, producing in thetrough over the slot a state of continuity of the bed of shale, thusallowing no coal to fall down with the shale through the slots. The slot,however, was replaced by a more spacious chamber. If this chamber be of sufficient capacity, it is found that the flap-valve can evacuate, at each oscillation, a certain quantity of shale,and that this action does not lower the upper surface of the bed of apparatus shown in Fig. 11 has therefore been evolved. This oscillating flap-valve, the principle object of which is to regulatethe evacuation of shale moving from a more or less inclined position toa horizontal position, produces to a certain degree an effect similar to theplunging in hydraulic jigs, namely, suction. However, the flap-valve Fig. 11.—Section ofFirst Sealed Eheolaveur. 4=- 7 Fig. 12.—Section ofImproved Sealed Rheolaveur. 230 TRANSACTIONS INSTITUTION OF MINING ENGINEERS. [VoL. Fig. 14.—Arrangement of AppARATrs to treat Large Sizes. 1921-1922.] FRANCE-FOCHiUET AND MITTON NOTES ON COAL-WASHING. 231 has since been perforated, thus allowing a free passage for the upwardcurrent of water coming underneath, and thereby eliminating thissuction. It can be readily understood, after what has been said, that theupward current in these Rheolaveurs can be of extremely low velocity,even when treating sizes up to 3 or 4 inches. Some detailed improvements have been added to the first design ofthe sealed Rheolaveurs fitted with flap-valves. One of these consists ofa vertical slide-valve (Fig. 12), which by moving horizontally allows ofa modification in the size of the separating-chamber, and also regulatesthe section of the shale orifice. An apparatus of extraordinary elasticity has, therefore, been arrivedat, permitting of the treatment in the same plant of either a great or asmall quantity of material, or of changin
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Keywords: ., bo, bookcentury1800, bookdecade1890, booksubjectmineralindustries
