LABORATORY RESEARCH AND INDUSTRIALISATION TEST ON TWO-STAGE CONTINUOUS CARBONISATION PRECIPITATION TECHNOLOGY FOR PRODUCING HIGH GRADE SANDY ALUMINA

In order to solve the problem of the poor quality of alumina product by the traditional carbonisation precipitation and the high loss of alumina by the deep desilication for the sintering liquor, the authors put forward Two-Stage Continuous Carbonisation Precipitation technology (TSCCP). Both laboratory and industrialisation test results have proved that this process has ingeniously solved the problem.

In the First Stage of Continuous Carbonisation Precipitation (FSCCP), high-grade sandy alumina is produced. In the Second Stage of Continuous Carbonisation Precipitation (SSCCP), the alumina is charged into the slurry flash tank (130–140°C) of the high-pressure digestion unit during the Bayer process of the Combination process. In this way, the shortcoming of low A/C of the high-pressure digestion liquor from diasporic bauxite can be overcome, and will produce high-grade sandy alumina. Furthermore, the process has other advantages such as increasing productivity of two-stage carbonisation precipitation, improving the evaporation performance of spent liquor of the SSCCP (deep precipitation), reducing gallium content in product alumina during the first stage, etc. So it is proposed that this process can be applied to alumina refineries with a Sintering process.