To provide a method for highly concentrating slurry of acicular or columnar light calcium carbonate by a causticizing method to solid concentration of ≥70 wt.% with a deliquoring apparatus as a substitute for a tube pressure filter without causing the problem of cake peeling.
In the method for highly concentrating, with a high pressure filter press apparatus, slurry of acicular or columnar light calcium carbonate having an average particle diameter of ≥2 μm produced by slaking quicklime with water or weak liquor and carrying out a causticizing reaction with green liquor in a causticizing step of a pulp making process by the sulfate process or soda process, the slurry is concentrated under pressure of 8-10 MPa for 20-60 min until a solid content of a cake attains to ≥70 wt.% so that the cake after dehydration has a thickness of ≥70 mm.
COPYRIGHT: (C)2009,JPO&INPIT
Haruo Kanano
Takashi Ochi
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