Abstract: Magnesium calcium sand was prepared by a two-step calcination process with nature dolomite as raw material.Dolomite was crushed，calcinted at 850 ℃，digestion，drying，and compressed into blocks，and then calcined at 1 650 ℃ to prepare magnesium calcium sand.The effects of digestion process conditions and molding pressure on sintering properties and hydration resistance of magnesium calcium sand were investigated.The optimum conditions were as follows：digestive water consumption was 3∶1（mass ratio of material and water），digestion time was 1 h，and molding pressure was 200 MPa.Molding pressure had little effect on the sintering properties and hydration resistance of magnesium calcium sand.

Key words: magnesium calcium sand, dolomite, digestion process, molding pressure