METHOD FOR PRODUCING WHITE PIGMENT BY USING INK-REMOVED SLUDGE OF PIGMENT-COATED WASTE PAPER AS RAW MATERIAL

摘要

PROBLEM TO BE SOLVED: To provide a method for producing a white pigment wherein an ink- removed sludge usually disposed of is used as the raw material and whereby the production is carried out easily at a low cost and a white pigment is obtained which has high whiteness and lightness and, when used as a pigment for papermaking, hardly abrades a papermaking wire and gives paper having opaqueness equal to that of paper obtained by using calcined clay.;SOLUTION: A sumi-removed sludge usually disposed of at the ink-removal step for recovering a pulp component from a pigment-coated waste paper is used as the raw material. After subjected to water removal and drying, the raw material is subjected to primary combustion at 400-700°C to carbonize organic components, then to coarse crushing as the primary crushing, to secondary combustion at 650-700°C to burn the carbonized organic components, and to grinding as the second crushing to an average particle size of 0.5-5 μm.;COPYRIGHT: (C)2001,JPO