Immobilization of lead and cadmium in fly ash
AssigneeAllied Corporation
InventorsMark J. O'Hara, Peter Urban
Life of this patent
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Abstract
Leaching of cadmium and lead from solid residues obtained in the incineration of refuse may be reduced to environmentally acceptable levels by the addition of calcium sulfide to such residues. A particularly convenient method involves the addition of dry lime and an aqueous solution of an inorganic salt supplying sulfide, especially an alkali metal sulfide, in equimolar quantities.
Claims8
A method of immobilizing cadmium and lead in a dry solid residue obtained from the burning of solid wastes comprising mixing said residue with an amount sufficient to reduce the leaching of cadmium to a level less than about 1 ppm and of lead to a level less than about 5 ppm of approximately equimolar proportions of lime and an aqueous solution of a soluble inorganic salt supplying sulfide.
A method of immobilizing cadmium and lead in a dry solid residue obtained from the burning of solid wastes comprising mixing said residue with calcium sulfide in an amount effective to reduce leaching of cadmium to a level less than about 1 ppm and of lead to a level less than about 5 ppm.
Dependencies are inferred from the claim text.