Utilizing blast furnace dust and sludge, by granulometrically sorting light component to give recyclable heavy fraction and zinc and/or lead enriched light fraction

摘要

A method for utilizing blast furnace dust and sludge, separated in a cyclone into a recyclable heavy component (a) and a non-recyclable light component (b) with high zinc and/or lead content, involves granulometrically sorting (b) to give (i) a coarse, heavy fraction depleted in zinc and/or lead (to be recycled to the furnace) and (ii) a fine, light fraction consisting of an aqueous suspension containing the fines fractions enriched in zinc and/or lead. A method is claimed for utilizing blast furnace dust and sludge, obtained by filtering and/or scrubbing the furnace combustion gas before release into the atmosphere to give a sludge, which is separated in a cyclone into a heavy component (a) (recycled to the furnace) and a light component (b) (not recycled due to the high zinc and/or lead content). The novel feature is that the light component (b) is granulometrically sorted to give (i) a coarse, heavy fraction depleted in zinc and/or lead (to be recycled to the furnace) and (ii) a fine, light fraction consisting of an aqueous suspension containing the fines fractions enriched in zinc and/or lead.