Process for treating residues from flue gas purification and/or flue gas desulphurisation plant

摘要

Two methods are described for the treatment of residues from exhaust gas purification or desulfurization, especially residues from refineries, the methods involving adding lime to a heated suspension of the residue, removing ammonia, and recovering a solid containing bound heavy metals. Treatment of residues from exhaust gas purification of desulfurization, especially residues from refineries, comprises: (i) heating an aqueous suspension of the residue to 50-80 degrees C; (ii) adding dissolved or non-dissolved lime and boiling so as to remove all of the ammonia; (iii) cooling to below 30 degrees C such that the pH is 8; and (iv) separating off the process water from the damp solid phase in which the heavy metals are bound. In a VARIANT damp solid is removed after step (i) and then treated as per steps (ii) - (iv) so as to give a gypsum-like product containing bound heavy metals.