| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for obtaining high-whiteness calcium carbonate usable as a pigment for coated paper from lime sludge produced when quicklime or a slaking liquid obtained by reacting quicklime with a sodium hydroxide-containing liquid is added to green liquor obtained in a pulp making process by the kraft process to causticize the green liquor. SOLUTION: In a method for producing calcium carbonate from lime sludge produced by causticizing green liquor obtained in a pulp making process by the kraft process with quicklime or a slaking liquid prepared by reacting quicklime with a sodium hydroxide-containing liquid, the lime sludge is passed through a flash drier using high-temperature hot air after passing through a white liquor recovery step, the resulting dried lime sludge is mixed with hydrous lime sludge at a filter outfall, and the mixture is dry-ground. The high-temperature hot air used is preferably hot air utilizing exhaust heat from a kiln rear end. COPYRIGHT: (C)2009,JPO&INPIT
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