METHOD AND APPARATUS FOR RECOVERING CALCIUM CARBONATE FROM PAPER SLUDGE WASTE

摘要

PROBLEM TO BE SOLVED: To provide a method for recovering calcium carbonate comprising a step of carbonizing a paper sludge waste, and a decarbonizing step of burning carbon in the resultant carbonized product, which enables the whiteness of a burned product to be high and the degree of decomposition of the calcium carbonate to be low.;SOLUTION: The method comprises a step 3 of carbonizing a papermaking sludge waste produced in a papermaking process in an oxygen-poor atmosphere, and a decarbonizing step 4 of burning a carbon component of the carbonized product at a surrounding gas temperature of not lower than 650°C. In the decarbonizing step 4, the partial pressure of carbon dioxide in the surrounding gas of the carbonized product is controlled to within 5-30%; thereby, the degree of decomposition of the calcium carbonate obtained is suppressed even when the temperature of the surrounding gas is raised in order to increase the whiteness.;COPYRIGHT: (C)2008,JPO&INPIT