| 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 quick lime to water of quick lime: water of 1:8 in formation and 1.6 wt.% calcium carbonate content is slurried by using a liquid having pH 6.8 into 30 wt.% concentration to give a milk of slaked lime. In the causticization reaction of a second process, the initial causticization reaction is carried out by firstly adding sodium carbonate at 0.04 g/min/g (a reduced value of quick lime of slaked lime) at 50 deg.C and successively at 0.22 (green liquor)/min/g (a reduced value of quick lime of slaked lime at the initial formation) addition rate of green liquor at 50<=.
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