TREATMENT METHOD FOR DUST IN CEMENT KILN EXTRACTION GAS

PROBLEM TO BE SOLVED: To treat selenium and heavy metals contained in dechlorination washing solution of dust in cement kiln extraction gas to 0.1 mg/l or less which is a effluent standard value related to the Water Pollution Control Law. SOLUTION: A treatment method for dust in cement kiln extraction gas comprises following steps:(1) a first step for solid-liquid separation after adding water to dust in the cement kiln extraction gas to form slurry;(2) a second step for solid-liquid separation wherein a ferrous salt compound is added to the liquid phase (referred to as raw water hereinafter) obtained in the first step after solid-liquid separation, until an oxidation reduction potential of the liquid phase is -600 mV or less, then pH is controlled to 8-10, and a polymer coagulant is added; and (3) a third step for adding a ferric salt compound to the liquid phase obtained in the second step after solid-liquid separation, controlling pH to 8-10, then adding the polymer coagulant to separate solid from liquid. COPYRIGHT: (C)2005,JPO&NCIPI