Mitsubishi Heavy Industries Limited

Kouichi Hirata

Susumu Kamikawa

Hironori Fujioka

Keiichi Sato

Hideaki Mizuki

Hiroshi Nakajima

Yoshimitsu Onaka

Akihiro Santo

An apparatus for producing reduced iron, and a compact drying method for application to the apparatus are disclosed. The apparatus comprises a pelletizer or a briquetter for mixing and agglomerating coal as a reducing agent and iron ore as iron oxide to form compacts, a dryer for drying the compacts, a circular rotary hearth type reducing furnace for reducing the dried compacts in a high temperature atmosphere, a first heat exchanger for performing heat exchange between a hot off-gas discharged from the reducing furnace and combustion air to be supplied to the reducing furnace, and coolers for cooling the hot off-gas. A second heat exchanger for heating drying air is disposed on an exit side of the first heat exchanger. The drying air heated by the second heat exchanger is supplied to the dryer to dry the compacts with the drying air which is scant in moisture. Consequently, highly efficient, stable drying in the dryer can be performed, and high quality reduced iron can be produced stably.

Apparatus for producing reduced iron and compact drying

An apparatus for producing reduced iron dries agglomerates, pelletized from a powdery mixture of an iron oxide powder and a reducing agent, in a drying chamber, preheats the dried agglomerates in a preheating chamber, and then reduces the preheated agglomerates in a high temperature atmosphere of a reducing furnace. In the preheating chamber, an off-gas from the reducing furnace is convected to preheat the dried agglomerates. A decrease in the fuel cost, and downsizing of the equipment can be achieved by effective use of the sensible heat of the off-gas discharged from the reducing furnace. Moreover, a downsized, simplified system for treatment of the off-gas is realized by decreasing the amount of the off-gas.

Apparatus for producing reduced iron

In the production of reduced iron by agglomerating a mixed powder of an iron material and a reducing agent to form compacts like briquettes or pellets, and reducing the compacts in a high temperature atmosphere, when the temperature of reduced compacts is 900&deg; C. or higher, the oxide content in the reduced compacts is set at 11% or more, and the basicity of the reduced compacts is set at 0.5 or higher.

Method for producing reduced iron

An apparatus for producing reduced iron by agglomerating a mixed powder of an iron material and a reducing agent to form compacts like briquettes or pellets, and reducing the compacts in a high temperature atmosphere is disclosed. In the apparatus, a rotary hearth in an annular form is rotatably supported. Right and left furnace walls and a ceiling are provided to cover an area above the rotary hearth, thereby forming a space portion in a high temperature atmosphere. A compact supply portion, and a compact discharge portion are provided adjacently in the ceiling. Partitioning members are provided as partitions between the compact supply portion, the compact discharge portion, and the high temperature atmosphere space portion.

An apparatus for producing reduced iron, and a compact drying method for application to the apparatus are disclosed. The apparatus comprises a pelletizer or a briquetter for mixing and agglomerating coal as a reducing agent and iron ore as iron oxide to form compacts, a dryer for drying the compacts, a circular rotary hearth type reducing furnace for reducing the dried compacts in a high temperature atmosphere, a first heat exchanger for performing heat exchange between a hot off-gas discharged from the reducing furnace and combustion air to be supplied to the reducing furnace, and coolers for cooling the hot off-gas. A second heat exchanger for heating drying air is disposed on an exit side of the first heat exchanger. The drying air heated by the second heat exchanger is supplied to the dryer to dry the compacts with the drying air scant in moisture. Consequently, highly efficient, stable drying in the dryer can be performed, and high quality reduced iron can be produced stably.

Method for drying compacts

There is provided a belt coating material for a belt type continuous casting, which is capable of adsorbing the intermediate between a cast slab and the coating material to prevent the intermediate from remaining on the slab, and reducing the averaged heat flux during the casting to avoid an occurrence of cracking in a medium carbon steel. The belt coating material comprises: (1) a powder having a composition comprising 10 to 40 weight % of SiO.sub.2, 1 to 10 weight % of Al.sub.2 O.sub.3, 10 to 40 weight % of CaO, 10 to 30 weight % of Na.sub.2 O, 1 to 10 weight % of MgO, 10 to 20 weight % of F, and 1 to 5 weight % of LiO.sub.2, the powder being prepared by once melting the blended components, solidifying the melt, and crushing it into the powder to adjust the average grain diameter of the powder to be equal to or smaller than 10 .mu.m; (2) 0.1 to 10 weight % of graphite mixed into the powder to provide a mixture, the graphite having the same grain diameter with the powder; and (3) 0.5 to 10 weight % of water glass, a viscosity increasing material, and water, each being added into the mixture so as to adjust the viscosity of the material to a predetermined value.

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Hiroshima, Japan

Kouichi Hirata