Integration of CO 2 Capture and Mineral Carbonation by Using Recyclable Ammonium Salts

A new approach to capture and store CO 2 by mineral carbonation using recyclable ammonium salts was studied. This process integrates CO 2 capture with mineral carbonation by employing NH 3 , NH 4 HSO 4 , and NH 4 HCO 3 in the capture, mineral dissolution, and carbonation steps, respectively. NH 4 HSO 4 and NH 3 can then be regenerated by thermal decomposition of (NH 4 ) 2 SO 4 . The use of NH 4 HCO 3 as the source of CO 2 can avoid desorption and compression of CO 2 . The mass ratio of Mg/NH 4 HCO 3 /NH 3 is the key factor controlling carbonation and the optimum ratio of 1:4:2 gives a conversion of Mg ions to hydromagnesite of 95.5 %. Thermogravimetric analysis studies indicated that the regeneration efficiency of NH 4 HSO 4 and NH 3 in this process is 95 %. The mass balance of the process shows that about 2.63 tonnes of serpentine, 0.12 tonnes of NH 4 HSO 4 , 7.48 tonnes of NH 4 HCO 3 , and 0.04 tonnes of NH 3 are required to sequester 1 tonne of CO 2 as hydromagnesite.