Direct Dry Carbonation of Mining Waste in a Fluidized Bed

In this work, the direct dry mineral carbonation of selected mining wastes using carbon dioxide deriving from combustion flue gas was evaluated. Specifically, coal fly ash from two Australian brown coal fired power plants, red mud from the refinement of bauxite into alumina and diamond tailings were considered, due to their relevant residual alkali content. These materials were tested in a laboratory-scale fluidized bed reactor at different temperatures (300- 450°C) in a reactive environment simulating the typical CO2 concentration in a combustion flue gas. The experimental results showed a low, but still interesting, CO2 capture capacity for all the materials tested, which appears to be more favorable in the lower temperature range, and with relatively fast kinetics, indicating the industrial relevance of the process.