Kabushiki Kaisha Kobe Seiko Sho

Kobe Steel, Ltd.

Kazuya Miyagawa

Shoji Shirouchi

Yoshimichi Takenaka

Masakata Shimizu

Haruhisa Iwakiri

Tsunao Kamijo

Takeshi Sugiyama

Takao Harada

Hidetoshi Tanaka

Makoto Nishimura

Sumito Hashimoto

Kojiro Fuji

Takao Umeki

Teruhisa Uehara

Pellets incorporated with a carbonaceous material of the present invention contain a carbonaceous material and iron ore mainly composed of iron oxide. The maximum fluidity of the carbonaceous material in softening and melting, and the ratio of iron oxide particles of 10 &mgr;m or smaller in the iron ore are within the range above a line which connects in turn points A, B and C shown in FIG. , including the line. This permits the production of pellets incorporated with a carbonaceous material having excellent thermal conductivity and high strength. Reduction of the pellets incorporated with a carbonaceous material produces reduced iron having high strength after reduction and a low fines ratio with improved productivity.

Pellets incorporated with carbonaceous material

Pellets incorporated with carbonaceous material and method of producing reduced iron

A carbonaceous material is controlled such that the amount of carbon is from 7 to 60 mass % based on the total amount of iron and Zn in a starting mixture comprising one or more of ducts containing iron oxide and Zn oxide and a binder in an amount to bond the dusts, and water is added to prepare green pellets incorporated with the carbonaceous material. Then, dry pellets prepared by drying the thus prepared green pellets into a reduction furnace, the dry pellets are heated by heat transfer, mainly, radiation such that a temperature elevation rate is from 3 to 13&deg; C./sec within a temperature range from 150 to 900&deg; C. of the pellets, thereby reducing Zn oxide and evaporating Zn, as well as reducing iron oxide to produce reduced iron pellets.

Reduced pellets

A carbonaceous material is controlled such that the amount of carbon is from 7 to 60 mass % based on the total amount of iron and Zn in a starting mixture comprising one or more of ducts containing iron oxide and Zn oxide and a binder in an amount to bond the dusts, and water is added to prepare green pellets incorporated with the carbonaceous material. Then, dry pellets prepared by drying the thus prepared green pellets into a reduction furnace, the dry pellets are heated by heat transfer, mainly, radiation such that a temperature elevation rate is from 3 to 13.degree. C./sec within a temperature range from 150 to 900.degree. C. of the pellets, thereby reducing Zn oxide and evaporating Zn, as well as reducing iron oxide to produce reduced iron pellets.

Method of producing reduced iron pellets

Iron oxide agglomerates incorporated with the carbonaceous material having a particle size within a range of about 10 to 30 nm are prepared upon production of reduced iron agglomerates. Then, the iron oxides agglomerates incorporated with the carbonaceous material were laid thinly at a laying density of less than 1.4 kg/m.sup.2 /mm or lower on a hearth of a moving hearth furnace. Subsequently, the iron oxide agglomerates are heated rapidly such that the surface temperature of the iron oxide agglomerates reaches 1200.degree. C. or higher within one-third of the retention period of time of the iron oxide agglomerates in the moving hearth furnace. Then, the iron oxide agglomerates are reduced till the metallization ratio thereof reaches 85% or higher to form reduced iron agglomerates and then the reduced iron agglomerates are discharged out of the moving hearth furnace. With the procedures, reduced iron agglomerates of a high average quality can be obtained at a high productivity.

Method of producing reduced iron agglomerates

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Kakogawa, Japan

Kazuya Miyagawa