Chemical fixation of desulfurization residues

Abstract

Chemical fixation of industrial desulfurization residues by forming an intimate admixture of the desulfurization residue, such as a flue gas desulfurization sludge, with an alkaline calcination stack dust, such as a cement kiln dust, in the presence of sufficient water to provide a mass of workable consistency, adjusting the pH of the alkaline mass with acid, such as sulfuric or phosphoric acid, to a value of below about 7, e.g. in the acid range of from below about pH 7 down to about pH 5, and drying the pH adjusted mass to constant weight, preferably after forming the pH adjusted mass into a selectively shaped article, whereby to produce an environmentally stable and leach-resistant hardened solid, cement-like fixed product.

Dependencies are inferred from the claim text.