Patent ID: 6319482
Filing Date: 2001-11-20
Classification: C22B,Y02P,Y10S

Abstract:
A method for treating a fly ash/APC residue containing chlorides, sulphates, lead and metals selected from the group consisting of calcium, potassium, and sodium, said method comprising:(a) washing and agitating the fly ash/APC residue with water using a water to fly ash/APC residue weight ratio value between 2.5:1 and 6:1 to form a residue slurry containing solubilized lead salts and calcium chloride;(b) filtering the residue slurry to remove a filtrate having a pH value between 11.8 and 14.0 and containing the solubilized lead salts and calcium chloride; and(c) recovering a first calcium enriched filter cake;wherein the steps (a) through (c) are conducted at ambient temperatures.