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AssigneeNippon Steel Corporation
InventorsTetuharu Ibaraki, Hiroshi Oda, Shoji Imura, Masaharu Takahashi
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The present invention provides a method and facility for preventing crumbling and powderization of green pellets when producing high strength green pellets using a powder feedstock and using the pellets in a rotary hearth reducing furnace and for efficiently reducing the same. It comprises kneading by a kneader 5 a feedstock of a powder of a fine particle size (20 to 80 wt % having size of not more than 10 μm) including a metal oxide and carbon-bearing powder fed from a feed storage tank 1 and producing green pellets by a pan type pelletizer 7. The green pellets are screened by a pellet screen 9, then dried by a pellet dryer 11 and reduced by firing in a rotary hearth reducing furnace 13. At that time, the green pellets are continuously conveyed to prevent crumbling.
1-13. (canceled)
A method of reduction of metal oxide-bearing green pellets for a reducing furnace characterized by charging (i) iron oxide-bearing green pellets for a reducing furnace obtained by shaping a feed powder containing an oxide-bearing powder and 5 to 30 wt % of a carbon-bearing powder, said feed powder containing 20 to 80 wt % of particles of not more than 10 μm size or (ii) iron oxide-bearing green pellets for a reducing furnace produced by a method characterized by pelletizing a feed powder containing a metal oxide-bearing powder and a carbon-bearing powder, wherein, when producing the green pellets, said feed powder includes 20 to 80 wt % of powder particles of not more than 10 μm size into a zone of a rotary hearth reducing furnace having a furnace ambient temperature of 900 to 1200° C. and reducing them by firing at a temperature of not less than 1200° C. for not less than 5 minutes.
A method of reduction of metal oxide-bearing green pellets for a reducing furnace characterized by pelletizing a feed powder comprised of a metal oxide-bearing powder and a carbon-bearing powder, including 20 to 80 wt % of powder particles having a size of not more than 10 μm, to make green pellets, screening the green pellets by a screen to remove undersized and oversized green pellets, reducing the moisture content by a pellet dryer, then charging the green pellets into a rotary hearth reducing furnace and reducing by firing the green pellets while continuously conveying green pellets between unit operations.
-19. (canceled)
A method of reducing metal oxide-bearing green pellets for a reducing furnace including the steps of:
Dependencies are inferred from the claim text.