To provide a treatment for readily modifying a large amount of dephosphorized molten iron slag to a raw material of high added value by adding a specific modifying agent to molten slag prepared by dephosphorizing molten iron and blowing oxygen into the slag and provide modified slag.
This slag-modification installation is a revolving furnace or a slag port equipped with a vessel for molten slag, a feeder for the modification materials and a blower for blowing or injecting oxygen. In the first method, metallic aluminum, metallic silicon and one or more kinds of substances containing the same are added to the dephosphorized molten slag as modifiers and oxygen in blown in. From the view point of costs, the modifier is preferably FeSi, aluminum ash and aluminum can wastes. The amount of the modifier is adjusted so that the ratios of SiO2 and Al2O3 are 1 and 0.3 to 1 of CaO, respectively. These modifier is injected in a granular or powder form using a carrier gas in order to secure the uniformity of the system. In the second method, aluminum oxide and silicon oxide are additionally added as modifiers.
IKEMIYA HIROYUKI
SHIROTA YOSHIYASU
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