Data for: Extraction of Alumina from Kaolin by a combination of Pyrometallurgical and Hydrometallurgical Processes

The increasing of aluminium demand globally raises the interest in developing alternative technologies to produce alumina from non-bauxitic sources, especially clays. This paper studies the extraction of alumina from the crude kaolin excavated from the Irkutsk region, Russia through the leaching process, using aqueous solutions of sodium carbonate as a leaching agent. Before the leaching process, the crude kaolin and limestone charge was sintered. The sintering process achieves the dehydroxylation of the kaolinite, which is the main mineralogical phase in the kaolin and activates its transformation to metakaolin. Metakaolin is an amorphous Al-Si phase, from which alumina could be easily leached. The annealed sintered material transform into dust that is suitable for the leaching process without any additional grinding. Sintering of the crude kaolin was taken place from 800-1400oC for 1h. The effect of briquetting pressure and sintering temperature on the recovery of alumina from kaolin, were studied. About 87% of the alumina in the crude kaolin was extracted at 1360°C and briquetting pressure of 5 MPa.