Abstract: Red mud from the production of alumina from bauxite by the Bayer process is converted to a flocculating agent by reaction with sulfuric acid and drying the reaction product by direct heat transfer thereto by contact with hot solid bodies and by contact with hot gases. The resulting solid product is a mixture of water-soluble sulfates of iron and aluminum with minor proportions of other water-soluble metal sulfates in the form of free-flowing discrete particles.

Abstract: In an aluminum electrolysis furnace provided with an anode structure located above a cathode forming part of the bottom of the furnace chamber, whereby direct electric current between the anode and the cathode causes aluminum to be obtained from aluminum oxide, a portion of the surface of the cathode facing the anode is covered with an electrically nonconductive material to create an electric current distribution which tends to improve the heat distribution within the furnace chamber.

Abstract: In the manufacture of phosphoric acid by treatment of phosphate ores with excess phosphoric acid and precipitation of calcium ions as calcium sulfate, the purity and quality of the byproduct calcium sulfate is substantially improved by subjecting the monocalcium phosphate extract of the ore before precipitation of calcium sulfate to one or more preliminary treatments, whereby contaminent ions are substantially and preferentially removed from the extract while the calcium remains substantially in solution. These preliminary treatments may include separation of fluoride by reaction with silicon compounds, separation of radium by reaction with barium compounds in the presence of sulfate ions, and separation of strontium as strontium sulfate.