Abstract
To utilize magnesium in seawater and fix carbon dioxide in exhausted gases, the direct carbonation method has been used to precipitate basic magnesium carbonate (BMC). BMC particles are used as a filler or anticaking agent for NaC1, which means it is necessary to control the size of BMC particles according to production needs. The aims of this study are to clarify the mechanism of reactive crystallization of BMC in the direct carbonation method, and to control the particle size of BMC.
BMC particles were produced in a gas blowing stirred tank crystallizer through a reaction between carbon dioxide and a suspended aqueous solution of magnesium hydroxide. The particles obtained were analyzed by means of X-ray diffraction and photographs were taken with a scanning electron microscope.
In this study, a mixture of spherical and tabular BMC particles was obtained. Agglomeration between particles was not observed very much during the growth of BMC. The particle size of BMC was influenced by the initial concenration and particle size of magnesium hydroxide, and the reaction temperature. By changing the initial concentration of magnesium hydroxide and the reaction temperature, it was possible to control the particle size of BMC to between 4-9 μm.
