CONVERSION OF INCINERATION ASH TO CEMENT RAW MATERIAL

摘要

PROBLEM TO BE SOLVED: To effectively remove chlorine while suppressing the elution of heavy metals from incineration ash by washing the incineration ash with water so as to adjust the liquid pH at a time of washing to a specific range. SOLUTION: Liquid pH at a time of washing operation is held to about 6-10 by a method wherein a predetermined amt. of an acid calculated from the chlorine content of incineration ash and an amt. of washing water is preliminarily added to and mixed with incineration ash or an acid is added to a liquid while the liquid pH at a time of washing is always monitored or an acid is added to the liquid or preliminarily added to and mixed with the incineration ash and this acid is also added to the incineration ash and water during washing operation. By this constitution, even chlorine in a form hardly soluble taken in incineration ash particles strongly is easily removed. Therefore, stable dechlorination treatment becomes possible and the elution of heavy metals is effectively suppressed.