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AssigneeNippon Steel Corporation
InventorsTetuharu Ibaraki, Hiroshi Oda, Shoji Imura, Masaharu Takahashi
Estimating the term…
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 pelletized 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.
A method of production of metal oxide-bearing green pellets for a rotary hearth reducing furnace characterized by pelletizing a feed powder containing a metal oxide-bearing powder and a carbon-bearing powder, wherein, when producing the green pellets, three or more types of feed powder, including at least two types of iron containing feed powder, are placed in separate storage bins, the mixing ratio of the mixture of feed powders is determined so that the mixture of said feed powders includes 20 to 80 wt % of powder particles of not more than 10 μm size, and said feed powders are fed out from said bins, and the mixture of said feed powders is pelletized into green pellets having a porosity of not more than 0.32 using a pan type pelletizer, and then the green pellets are dried in a dryer at a temperature of not higher than 250° C., and then, immediately after drying, feeding the green pellets into the rotary hearth furnace.
A method of production of metal oxide-bearing green pellets for a rotary hearth reducing furnace characterized by pelletizing a feed powder containing a metal oxide-bearing powder and 5 to 30 wt % of a dry distilled carbon-bearing powder, wherein, when producing the green pellets, three or more types of feed powder, including at least two types of iron containing feed powder, are placed in separate storage bins, the mixing ratio of the mixture of feed powders is determined so that the mixture of said feed powders includes 20 to 80 wt % of powder particles of not more than 10 μm size, and said feed powders are fed out from said bins, and the mixture of said feed powders is pelletized into green pellets having a porosity of not more than 0.32 using a pan type pelletizer, and then the green pellets are dried in a dryer at a temperature of not higher than 250° C., and then, immediately after drying, feeding the green pellets into the rotary hearth furnace.
A method of production of metal oxide-bearing green pellets for a rotary hearth reducing furnace characterized by pelletizing a feed powder containing a metal oxide-bearing powder and 10 to 35 wt % of fine coal, wherein, when producing the green pellets, three or more types of feed powder, including at least two types of iron containing feed powder, are placed in separate storage bins, the mixing ratio of the mixture of feed powders is determined so that the mixture of said feed powders includes 20 to 80 wt % of powder particles of not more than 10 μm size, and said feed powders are fed out of said bins, and the mixture of said feed powders is pelletized into green pellets having a porosity of not more than 0.32 using a pan type pelletizer, and then the green pellets are dried in a dryer at a temperature of not higher than 250° C., and then, immediately after drying, feeding the green pellets into the rotary hearth furnace.
A method of production of metal oxide-bearing green pellets for a rotary hearth reducing furnace characterized by pelletizing a feed powder containing a metal oxide-bearing powder and a total of 10 to 60 wt % of two times the percent by weight of a dry distilled carbon-bearing powder and the percent by weight of fine coal, wherein, when producing the green pellets, three or more types of feed powder, including at least two types of iron containing feed powder, are placed in separate storage bins, the mixing ratio of the mixture of feed powders is determined so that the mixture of said feed powders includes 20 to 80 wt % of powder particles of not more than 10 μm size, said feed powders are fed out from said bins, and the mixture of said feed powders is pelletized into green pellets having a porosity of not more than 0.32 using a pan type pelletizer, and then the green pellets are dried in a dryer at a temperature of not higher than 250° C., and then, immediately after drying, feeding the green pellets into the rotary hearth furnace.
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