| 摘要 |
PROBLEM TO BE SOLVED: To obtain inexpensive aragonite-based burr-like calcium carbonate having excellent opacity, wire wear resistance, etc., useful as a filler for paper- making or a pigment by using a causticization process. SOLUTION: In a first process, slaked lime having the molar ratio of quicklime to water of 1:1 to 1:5 in formation and 0.05-8 wt.% calcium carbonate content is slurried by using a liquid having pH 5.5 to 13.5 into 10-60 wt.% concentration to give a milk of slaked lime. In the causticization reaction of a second process, the addition rate of green liquor is adjusted to 0.02-0.4 cc (green liquor)/min/g (a reduced value of quicklime) and the reaction temperature is 25-75 deg.C.
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