Abstract: A thickening tank has a peripheral overflow launder and a centrally disposed feed well. Feedstock slurry is fed to a mixing box which also receives supernatant liquid and is supplemented by flocculated material flowing into the interior of the feed well onto a distributor baffle plate. The supernatant liquid is delivered at a controlled rate from a receiving vessel formed by an upright cylinder provided at its lower end with an impeller of a lift pump which is operated by a controller positioned at the upper end of a vertical drive shaft extending axially through the receiving vessel. The feed well is surrounded by a second launder which is closed at its base and formed with a cup. The lower end of the receiving vessel is spaced from the floor of the cup to draw supernatant liquid exclusively from the second launder rather than from the thickener tank.

Abstract: A thickening tank has a peripheral overflow launder and a centrally disposed feed well. Feedstock slurry is fed to a mixing box which also receives supernatant liquid and is supplemented by flocculated material flowing into the interior of the feed well onto a distributor baffle plate. The supernatant liquid is delivered at a controlled rate from a receiving vessel formed by an upright cylinder provided at its lower end with an impeller of a lift pump which is operated by a controller positioned at the upper end of a vertical drive shaft extending axially through the receiving vessel. The feed well is surrounded by a second launder which is closed at its base and formed with a cup. The lower end of the receiving vessel is spaced from the floor of the cup to draw supernatant liquid exclusively from the second launder rather than from the thickener tank.