Precipitation of calcium carbonate was carried out in a draft-tu be reactor by mechanical agitation of calcium hydroxide solution with carbon dioxide. The circulation of a reactive mixture was created by gas flow and a stirrer. It was observed that a higher circulation decreased the precipitation time and improved CO2 consumption. A higher circulation velocity of liquid contributed to smaller calcium carbonate particles at the end of precipitation. (C) 2008 Elsevier B.V. All rights reserved.