To provide a method for efficiently and economically producing high-quality white inorganic particles on a large scale which can be effectively utilizable as a filler for papermaking and a pigment for coated paper from papermaking sludge discharged from a papermaking plant.
In the method for producing white inorganic particles by firing papermaking sludge in a cylindrical heat treatment furnace, sludge forming particles are granulated, formed and fired in such a way that the sizes of sludge forming particles are in the range of 2-30 mm in length, width and height, respectively, each interior angle formed at a mutual contact part (tangent line part) of each plane constituting the sludge forming particles has an obtuse angle exceeding 90 degrees and the sludge forming particles and has no sharp-pointed parts or corner parts of right angle or acute angle in the whole outer peripheral area of the sludge forming particles so that collapses of edge parts of sludge forming particles and sludge forming particles themselves are prevented and occurrence of fine papermaking sludge particles produced during firing is suppressed to give white inorganic particles having excellent whiteness and excellent production efficiency in a period in which the qualities are attained.
OGAWA YUICHI
HANABUSA YOSHIKI
YANAGIDA TOMOHIRO
HIRABAYASHI TETSUYA
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