PURPOSE: To remarkably shorten the aging treatment period for stabilizing free CaO by pressing and heating a steel-making slag containing free CaO in a steam atmosphere having specific pressure and temperature.
CONSTITUTION: Steel-making slag containing free CaO is crushed and heated under pressure in a steam atmosphere of 1.2-10kg/cm2 pressure and 80-180°C. The treatment is preferably carried out in a mixed atmosphere obtained by adding CO2 gas to the above steam. When the pressure is below the lower limit, too long time becomes necessary for the stabilization and the efficiency is lowered. Although there is no particular restriction on the upper limit, the process is preferably carried out under a pressure lower than 10kg/cm2 from the restriction of e.g. the High-Pressure Gas Regulations and from the viewpoints of cost and apparatus. The stabilization is slowed down at a temperature below the lower limit. The upper limit of the temperature is not restricted, however, it is 180°C in the case of treating in a closed apparatus containing water under a pressure of <10kg/cm2 taking consideration of the saturated steam pressure.
MATSUNAGA HISAHIRO
NOZAKI TSUTOMU
AMATATSU MASAYOSHI
