Plenary Talk: Fluidized Bed Mineral Roasting: From Fundamental to Application

China has large reserves of low grade minerals, which are difficult to be beneficiated by conventional processes, and are currently not utilized. To utilize these minerals, it is therefore often needed to transform ores from difficult-processed phases and structures to more easily processed phases and structures, normally through chemical processes like roasting via oxidation, reduction, etc. While roasting can be processed via reactors like shaft furnaces, rotary kilns, fluidized beds, etc., fluidized bed (FB) reactors have been proven to be the most efficient reactors for mineral roasting. In the present presentation, fluidized bed roasting practices of our group will be introduced.

Over the past decade, several fundamental aspects related to FB mineral roasting have been explored, like the influence of roasting conditions on the phase and structure change, process intensification via FB configuration and internals, adjustment of means residence time (MRT) for the coarse and fine particles, optimization of FB scale-up through CFD simulations, etc., have been systematically investigated. Moreover, our practices on engineering implementation of fluidized bed mineral roasting will also be introduced, including oxidative-reductive roasting of Panzhihua ilmenite for the production of synthetic rutile, magnetizing roasting of low grade iron ores for iron ore beneficiation, direct reduction of iron ore concentrate for the development of non-blast furnace ironmaking technology, calcination of aluminum hydroxide to produce 50-70% a-Al₂O₃, reduction of low grade pyrolusite for MnSO₄ production, etc. Several pilot and commercial scale plants have been established with cooperation of various companies, e.g. 200 kt/a reduction plant has been successfully put in operation for over 3 years for the reduction of low grade pyrolusite in Yunn province, China.