Abstract: Improved apparatus and method are described for the removal of light metals; sodium, lithium, calcium and magnesium, from virgin aluminum tapped from a Hall Heroult reduction cell using LiF-modified or LiF+MgF2 electrolyte. The method is performed in a crucible or at a station intermediate between the cells and furnaces in a cast house. Fine particulate aluminum fluoride and/or sodium aluminum tetrafluoride are transported by a gas or gas mixture into the molten aluminum in a manner such that the light metals are preferentially removed or their concentration substantially lowered through: a) the axle of a specially designed spinning impeller; b) partially through the axle of a specially designed spinning impeller and partially through one or more pipes equipped with dispersers for dispersing into the molten metal flow close to the spinning impeller; or c) through one or more pipes equipped with dispersers for dispersing into the molten metal flow close to the impeller fastened to a solid axle.

Abstract: The present invention relates to a method of and an apparatus for controlling the combustibility of volatile hydrocarbons and particulate matter in an exhaust gas stream driven off from a carbon product being baked in a furnace. In a prebaking stage, the carbon product is heat treated in a temperature range of 300.degree. C. to 600.degree. C. in order to drive off the volatile hydrocarbons and particulate matter and form the exhaust gas stream. The exhaust gas stream is heated to a temperature of at least 900.degree. C. and at least one heat transfer medium is force-drafted and mixed into the exhaust gas stream so that the stream contains at least approximately 6% oxygen. The volatile hydrocarbons and particulate matter in the exhaust gas stream are combusted into non-polluting compounds having an opacity less than 40% for exhaustion from the furnace into the outside atmosphere.

Abstract: This invention relates to a method for recovering aluminum hydroxide from alunite ore by roasting the ore to remove water of hydration, roasting it again in a reducing atmosphere to remove sulfate, roasting a third time in an oxidizing atmosphere to convert any sulfides formed in the second roast, leaching with a weak base, leaching with water to remove potassium and sulfate, extracting the aluminum content with a mixture of sodium hydroxide and potassium hydroxide, removing contaminant silica from the leach solution, and precipitating aluminum hydroxide by cooling and seeding the solution.

Abstract: The process for degassing aluminum and aluminum alloys comprising treating the molten metal with a gaseous mixture consisting essentially of fluorine, hydrofluoric acid, carbon monoxide and carbon dioxide. Fluorine, hydrofluoric acid, carbon monoxide and carbon dioxide are produced during the electrolytic reduction of alumina to form aluminum, therefore, the gaseous mixture resulting from this electrolytic reduction may be used to degas aluminum and aluminum alloys.