Preparation of Alumina from Fly Ash by Sulfuric Acid

Extraction metallurgy level alumina from fly ash through high-pressure leaching, removing iron, crystallizing and roasting processes were considered. The optimum conditions of high-pressure leaching, removing iron and roasting processes were obtained by experiments. The leaching rate of Al2O3can reach 93.1% and the purity of Al2O3product can reach above 98% under these conditions. The iron content in Al2(SO4)3solution can decrease from 1.21% to 0.10% when fly ash as alkaline agents.

Second-Generation Aluminium Extraction Residue Used as Devitrification Aid for Glass-Ceramics

Brazil has one of the world’s most important Bauxite deposits, the raw material for the aluminium extraction metallurgy. This work is focused on finding a suitable application for the white dross residue (WDR), a second-generation waste material produced during the metal recovery from the slag left after the primary extraction of aluminium from the ore. A commercial lime-silica based glass frit was used, to which WDR additions were made (up to 30 wt.%), aimed at studying the devitrification process of the glasses produced. Such mixtures were melted at temperatures varying from 1100 to 1500°C and the resulting fritted glasses were heat treated at 900°C. The starting materials and the mixtures thereof were characterized before and after thermal treatment by differential thermal analysis, X-ray diffraction and fluorescence, and scanning electron microscopy. The results obtained showed that the WDR is easily incorporated into the glass matrix and causes easy devitrification after short heat treatment periods at low temperature.