A New Aqueous Mineral Carbonation Process Utilizing Bipolar Membrane Electrodialysis

摘要

A new aqueous mineral carbonation process which utilizes bipolar membrane electrodialysis wasproposed. The proposed process consists of four unit operations, (a) acid leaching of alkaline metals(Ca~(2+) /Mg~(2+)) from mineral compounds by HNO3, (b) Na2CO3 generation via absorption of CO_2 intoNaOH, (c) Ca and Mg carbonate precipitation by addition of Na2CO3, and (d) HNO3/NaOH regenerationfrom NaNO3 solution with bipolar membrane electrodialysis. Regenerated HNO3 solution is then recycledto the acid leaching step. In the Na2CO3 generation step, regenerated NaOH solution is contacted with thegaseous CO_2 to form Na2CO3 solution. Exhaust gas from power plant can be directly used withoutcompression. Experimental studies were conducted to confirm the technical feasibility of this process.Results demonstrate that HNO_3 and NaOH were successfully regenerated from NaNO3 solution by usingbipolar membrane electrodialysis. This result suggests that we can utilize alkaline metals in mineralcompounds by using acid and HNO3 and NaOH solution can be used cyclically in this process.