Abstract: A flotation device for mixing and aerating an ore-containing slurry, comprising a tank having a conical-shaped floor. A vertically positioned flotation assembly is located within the tank. The open bottom of the flotation assembly is shaped is positioned above the conical portion of the floor. The assembly has a middle section having a cage with spaced, vertical bars forming its outer circumference. A rotatable impeller is located within the middle section which draws slurry from the tank through the bottom section and into the middle section and thereafter through the cage and out of assembly. The impeller is attached to a rotatable shaft which is connected at its bottom portion to the upper side of the back plate to rotate the impeller in a plane normal to the shaft. A hollow, vertically situated tubular shaped upper section is located directly above the middle section through which the shaft passes. The upper section has an opening at its lower end which is blocked by the back plate of the impeller.

Abstract: Disclosed is a process for the elimination of volatile, foul-smelling organic compounds which are liberated in a gas suspension calciner process utilized to manufacture alumina. The process comprises recirculating captured alumina dust on which undesirable volatile organic compounds are adsorbed to a location in the manufacturing process (1) at or upstream (based on the path of the conveying gases) from the gas suspension calciner and (2) which is operating at a temperature of about 700 ° C. or higher. The adsorbed organic compounds are stripped off the alumina dust and are subsequently directed by process air into the gas suspension calciner furnace which is operating above 1000 ° C. under oxidizing conditions. Under such conditions the organic compounds are oxidized to H2O vapor and CO2. It is a preferred feature that the volatilized organic compounds are adsorbed on the alumina dust in a baghouse.