To remarkably reduce the thermal load needed to vaporize water and decompose powdery wet raw material in a smelting reduction furnace by regulating the exhaust gas temp. after heat-exchanging to a specific value or higher, at the time of drying the powdery raw material while executing the heat exchange with the powdery wet raw material containing metal high in vaporizing pressure by utilizing the exhaust gas sensible heat in a vertical type smelting reduction.
The exhaust gas generated in the vertical type smelting reduction furnace 1 is supplied to an exhaust gas piping 5 arranged in a heat exchanger 4 through a cyclone 14 and metallic sludge, etc., containing valuable metal is brought into contact with the heated piping surface to dry and remove the moisture contained in the metallic sludge, etc. At this time, the exhaust gas temp. after heat-exchanging, is made to ≥800°C and the dried metallic sludge is transported to a powder injecting device 8 through a hopper 6 for dried sludge and a hopper 7 for discharging and injected from upper step tuyeres 9 in the vertical type smelting reduction furnace 1 and smelted. By this method, the metallic sludge can be dried within the wide range of about 10-50% water without casing the problem such as the sticking of low m.p. metal in the heat exchanger 4.
ISHIWATARI NATSUO
HARA YOSHIAKI
ITAYA HIROSHI
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