Treatment of steel plant sludges in a multi-stage furnace

摘要

The treatment procedure consists of the following stages: adjusting the CaO content of the sludge by adding quicklime and/or slaked lime to give an available CaO content of 3 - 8 per cent by weight; adding a carbon fuel; introducing the sludge into the upper stages of a multi-stage furnace; firing up the furnace and transferring the sludge gradually to the lower stages; and regulating the outlet gas temperature of the furnace to at least 500 deg C, and that of the treated sludge discharged from the furnace to between 700 and 800 degrees C. The carbon fuel can be in the form of coal, added at a rate of at least 100 kG per tonne of sludge, or gas or fuel oil injected through burners. The treated sludge can be subjected to pyrometallic treatment in an electric furnace, and zinc can be extracted from it before pouring cast iron and slag.