Patent ID: 6403045
Filing Date: 2002-06-11
Classification: A62D,B09B,Y02W

Abstract:
A method of treating residues after purification of fumes from incinerated household rubbish and/or industrial waste, comprising the steps of:Aâ€”desalting residues by washing with sodium carbonate in sufficient quantity or slightly in excess for solubilising all salts including sulphates and for precipitating soluble calcium, at a pH above 11, followed by separating solids from liquids to obtain a desalinated cake and a solution; Bâ€”leaching the desalinated cake from step A with sodium carbonate in sufficient quantity or slightly in excess for reacting with lime present in the cake, or added if necessary, to obtain an alkalinity necessary for solubilisation of amphoteric metals, at a pH above 12, solids being separated from liquids so as to obtain a decontaminated residue cake and a supernatant which is neutralised with carbon dioxide, recovered solution being filtered so as to obtain metal hydroxide sludge and an aqueous solution of sodium carbonate which can be recycled to said step B, and Câ€”neutralising the decontaminated residue cake from step B at a pH between 6.5 and 8.5.