SILICA AND IRON OXIDE EXTRACTION FROM ALUMINA-CONTAINING SWEEPINGS OF ALUMINUM PRODUCTION

Abstract

The paper suggests a method for recovering contaminants from aluminum-production waste called sweepings to return them further to the electrolytic cell. It is proposed to use the grinding – sizing – reverse flotation – thickening scheme for material beneficiation. Flotigam 7266 (Clariant, Germany), a mixture of primary fatty alkylamines, was used as a flotation reagent in the study to completely remove silicon and iron oxides. The combination of pine oil mixed with kerosene was used to remove carbon particles. Flotation was conducted on the FML 0,3 flotation machine. The raw material, chamber product and tailings were analyzed for the content of carbon and aluminum, iron and silicon oxides using X-ray diffraction, X-ray phase and chemical analysis. It was found that processing the overall mass of the material does not provide a product with an acceptable content of silicon and iron oxides. Based on the X-ray phase analysis of various raw material fractions it was proposed to process material fractions containing minimum contaminants (carbon, silicon and iron oxides). Two fractions were chosen for flotation processing: –0,071 mm and +5,0 mm according to the X-ray diffraction analysis of various material fractions. Processing the first fraction allowed obtaining the chamber product of an acceptable quality. The coarse electrolyte-containing fraction (+5,0 mm) provided the product with the high content of alumina and fluorinated components and low content of carbon and iron oxide, but with a significant amount of silicon oxide. Further use of this product is possible to obtain silicon-aluminum alloys.