PURPOSE: To greatly reduce the number of processes and steps and enhance the yield of products, by prescribing the quantity of mixed water relative to that of calcium hydroxide, and extruding a mixture of them at prescribed formation pressure and grain diameter.

CONSTITUTION: 100 parts of calcium hydroxide are mixed with 35 to 60 parts of water. The mixed material is formed by screw extrusion at formation pressure of 1.0 to 20kg/cm2 and a grain diameter of 1∼4mm. Thus, the quantity of the mixed water is reduced by half and the time for drying the formed material is greatly shortened. Since the grain diameter at the time of the extrusion is 1∼4mm, a pulverizing process is omitted to greatly enhance a production capacity, avoid a pulverization loss and highly increase the yield of products.