Formation of Mg/sub 3/Ca(SO/sub 4/)/sub 4/ during the sulfation reaction of dolomite

In the course of investigations on the kinetics of sulfation of natural dolomite, CaMg(CO/sub 3/)/sub 2/, as the sorbent for SO/sub 2/, it has been found that Mg ions can be made to sulfate, leading to the formation of a double salt, Mg/sub 3/Ca(SO/sub 4/)/sub 4/. This compound also forms when synthetic dolomites are used in sulfation experiments. In sulfur emissions control processes, SO/sub 2/ may be sorbed by dolomite in its natural form, in its half-calcined condition (CaCO/sub 3/ . MgO), or when fully calcined (as CaO . MgO). The form used will depend on the operating requirements of a particular emission control process. Chemical-crystallographic studies of the binary sulfate compound have been undertaken in an effort to gain an understanding of the possible mechanisms involved in its formation in dolomite. Preliminary results of these investigations are described.