PURPOSE: To improve a content of roundheaded aragonite type by introducing a mixed gas of a carbon dioxide gas and air into a milk of lime of quick lime or slaked lime under a specific reaction condition.
CONSTITUTION: Limestone containing 0.5-1wt.% magnesium oxide is baked and staked with water to give a milk of lime of quick lime or slaked lime having 7-20wt.% slaked lime concentration. Air mixed with 20-30vol.% carbon dioxide gas is introduced at 1,000-4000ml/minute to 800-2,000ml of the milk of lime while maintaining the milk of lime at 30-40p°C to carry out carbonation reaction and the reaction is completed at a reaction finishing point to rapidly drop electric conductivity of the milk of lime and to show the minimum value. Consequently, a precipitated calcium carbonate light rich in aragonite type as roundheaded aggregate crystal is obtained.
UCHINO YOSHITOSHI
SUENAGA TOMOKO
SAKATA KAZUNARI
IIDA TADAICHIRO
IWAKURA MINORU
KUMAMOTO PREFECTURE
F C RAIMU KYODO KUMIAI
Kobori Masashi
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