Abstract: in a hot combustion gas stream are removed therefrom by oxidizing the elemental mercury, to form a mercury compound, and adsorbing the mercury compounds on adsorbent particles such as activated alumina. Oxidation is catalytically promoted. After adsorbing a substantial quantity of mercury compounds, the spent adsorbent particles can be regenerated and re-used by heating the particles to decompose and drive off the mercury compounds. In another embodiment, oxidation of the elemental mercury is catalytically promoted at a catalyzing station, and the mercury compounds are removed from the gas stream by scrubbing.

Abstract: An oxidation resistant, non-consumable anode, for use in the electrolytic reduction of alumina to aluminum, has a composition comprising copper, nickel and iron. The anode is part of an electrolytic reduction cell comprising a vessel having an interior lined with metal which has the same composition as the anode. The electrolyte is preferably composed of a eutectic of AlF.sub.3 and either (a) NaF or (b) primarily NaF with some of the NaF replaced by an equivalent molar amount of KF or KF and LiF.

Abstract: Finely divided particles of alumina are electrolytically reduced to aluminum in an electrolytic reduction vessel having a plurality of vertically disposed, non-consumable anodes and a plurality of vertically disposed, dimensionally stable cathodes in closely spaced, alternating arrangement with the anodes. A horizontally disposed, gas bubble generator is located at the vessel bottom, underlying the cathodes and the spaces between each pair of adjacent electrodes. The vessel contains a molten electrolyte bath composed of (1) NaF+Alf.sub.3 eutectic, (2) KF+AlF.sub.3 eutectic and (3) LiF. The alumina particles are maintained in suspension in the molten electrolyte bath by rising gas bubbles generated at the anodes and at the gas bubble generator during the reduction process.

Abstract: A cell for the electrolytic reduction of alumina to aluminum comprises an electrolyte bath composed of halide salts having a density greater than aluminum but less than alumina. A non-consumable anode is located at the bottom of the bath, and a dimensionally stable cathode coated with titanium diboride is spaced above the anode and totally immersed in the bath. Particles of alumina are introduced into the bath where the alumina dissolves and forms ions of aluminum and oxygen. The oxygen ions are converted at the anode to gaseous oxygen which bubbles upwardly through the bath, agitating the bath. As a result, the bath is substantially saturated with dissolved alumina in the region of the anode, and the build-up of a layer of undissolved alumina on the anode is prevented. The aluminum ions are converted to metallic aluminum at the cathodes, and molten aluminum accumulates as a pool atop the bath above the cathodes.