Abstract: The dolomite deposit is huge in China.The carbonation of calcined dolomite slurry is one of the key steps in the production of magnesium compounds，such as light magnesium carbonate and magnesia，by carbonating dolomite，because it relates to magnesium dissolution rate，calcium content，and production cost.The relationship among magnesium dissolution rate，calcium content in Mg（OH）₂  solution，reaction temperature，pH at end point，and mass concentration of the calcined dolomite slurry were studied through the single factor and orthogonal test so as to increase the magnesium dissolution rate and to improve the separation efficiency of calcium and magnesium system.The study showed that the main influence factor on magnesium dissolution rate and calcium content in Mg（OH）₂  solution was pH，and the optimal conditions of carbonation of calcined dolomite slurry were decided as follows: the mass concentration of the calcined dolomite slurry was 9.00 g/L（calculated as MgO），the reaction temperature was 30 ℃，and the pH at end point was 7.50.Following the above conditions，the magnesium dissolution rate was 74.49%， and the calcium content in Mg (OH)₂ solution was 0.10 g/L.

Key words: calcined dolomite slurry, carbonation reaction, magnesium carbonate, magnesia, dolomite