Slag Furnace & Fume Leach

A metallic slag, containing all of the iron and most of the zinc from the Kivcet Furnace, is transferred in 70 tonne batches to a coal-fired fuming furnace. To recover the zinc, fine coal and air are injected one metre below the top of the slag bath. The heat generated causes the zinc to fume as a vapour from the furnace bath and is immediately reoxidized by tertiary air above the bath to form zinc oxide fume. This fume and hot gases are cooled in a waste heat boiler before passing through a baghouse to collect the zinc fume for treatment in the adjacent Fume Leach Plant. In this plant, halogens (chlorine and fluorine) are removed by a sodium bicar-bonate treatment.

Exhaust and ventilation gases from this entire process are discharged to a tall stack. The molten barren slag is granulated in water then collected for sale to cement manufacturers or sent to land storage.

The Slag Furnace is instrumental in the recovery of zinc and co-products from the slag.