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.

Abstract: A method and apparatus are disclosed for continuously drying, preferably with agglomeration and/or coating and sizing, and separating a solid product from a liquid feed material, especially bauxite slurry which passes through a very sticky phase during drying, without significant encrustation of the equipment used.

Abstract: This invention relates to a method for the production of anhydrous alumina having a desired .alpha.-conversion from alumina trihydrate.This method is directed to production of anhydrous alumina having a desired .alpha.-conversion from alumina trihydrate in which water is removed in a precalcining zone wherein the alumina trihydrate is heated to a temperature below 450.degree. C. Then, the precalcined dehydrated alumina is recrystallized to .alpha.-alumina in a reaction chamber by directing an oxygen containing gas to the reaction chamber, mixing and suspending the precalcined alumina and fuel in the oxygen containing gas and feeding the mixture to a combustion zone, followed by exothermal recrystallization of the alumina which is initiated by rapidly heating the precalcined alumina by burning the fuel in the oxygen containing gas in the hot combustion zone and withdrawing the recrystallized alumina from the top of the reaction chamber suspended in a combustion gas stream.