| 摘要 |
PROBLEM TO BE SOLVED: To attain the recovery of useful metals and the utilization of sewage treating sludge high in the concn. of heavy metals by feeding waste together with the carbines of sewage treating sludge to a heating furnace, heating and reducing metallic oxides in the waste and executing metallizing. SOLUTION: Ferrous waste is composed of steel making dust, blast furnace dust and pickling sludge of iron steel material or the like essentially consisting of iron and contg., as assistant components, the oxides of zinc, lead or the like. Carbides obtd. by subjecting sewage treating sludge high in the concn. of heavy metals to dehydrating, drying and carbonizing and ferrous waste are kneaded together with a binder, and granulating is executed thereto. The obtd. pellets are charged onto a rotary hearth of a rotary hearth furnace, and heating and reducing are executed. Since the metallized iron is left in the treating furnace, it is recovered from the bottom part of the side wall of the treating furnace. Since the metallic oxides in the ferrous waste of zinc, lead or the like are metallized, vaporized and entrained with exhaust gas, after the exhaust gas is cooled, it is collected by a dust collector and is recovered. Iron, zinc, lead or the like in the carbides are similarly recovered. The amt. of a reducing material to be used can be reduced, and the sewage treating sludge can be utilized.
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