The preparation of basic magnesium carbonate (BMC) by the simultaneous absorption of NH3 and CO2 into MgCl2 solution in a rotating packed bed (RPB) was studied. The influences of the operating conditions including the rotation speed, liquid volumetric flow rate, gas volumetric flow rate, reaction temperature and initial concentration of MgCl2 solution on the crystal structure and morphology of BMC were investigated. The scanning electron microscope image of the as-prepared BMC showed that the BMC particles had a unique rose-like structure with a mean size of 53 mu m, a petal thickness of 20 nm and a particle size distribution mainly in the range of 2.8-7 mu m. (C) 2015 Elsevier B.V. All rights reserved.