Coproduction of metal oxide and CO2 through decomposition of carbonate in a moving bed with a central gas-flow channel

Abstract

During carbonate calcination process, the block ores are often directly heated by high-temperature flue gas, which inevitably dilutes the potentially high-concentration CO2 from carbonate decomposition. In this study, we well implemented the coproduction of lightly burned magnesia (LBM) and high-concentration CO2 through decomposition of small-size magnesite in a devised novel moving bed reactor. The reactor is installed with a central gas-flow channel as internals to convert the moving bed into a radially flowing reactor, making it can process small-size particles. Verification of this design was implemented in an electrically heated pilot-scale facility processing about 10 kg h−1 magnesite (0–6 mm), and gaseous product contains about 99% CO2. Systematic tests employing laboratory fixed bed reactors with and without internals further showed that the thickness of particle layer between the heating wall and the central internals substantially affects heat transfer from outside to the inside, thus influencing the decomposition. It is particularly for magnesite because the formed LBM is both heat-resistant and flame-retardant. Therefore, an updated reactor for small-size carbonates decomposition and coproduction of CO2 is proposed.