Specialized metallurgical processes – compositions for use therei – Processes – Consolidating metalliferous material by agglomerating,...
Patent
1994-04-29
1996-05-28
Andrews, Melvyn
Specialized metallurgical processes, compositions for use therei
Processes
Consolidating metalliferous material by agglomerating,...
75759, 75769, 75316, C22B 120
Patent
active
055207197
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for producing a sintered ore for use as a raw material for the production of molten metal in a blast furnace and the like and particularly to a process for producing a sintered ore which enables recovered iron scrap to be reused as a raw material for iron in a blast furnace.
PRIOR ART
In recent years, a large quantity of an iron scrap called light-weight debris derived from automobiles, domestic electric appliances, vessels, etc. (hereinafter referred to simply as "scrap") has become available, which has led to an ever-increasing demand for the utilization thereof. This type of scrap is chipped into smaller debris by a shredder or a cutter. However, the debris is still so bulky that it is unwelcome for use in an electric furnace, a converter or the like. Consequently, at the present time, in many cases, large scrap, having a good quality called "heavy debris", is used in an electric furnace, converter, etc. In the past, tests for direct use of light-weight debris in a blast furnace have been carried out. However, there occurred significant problems including separation from ore and segregation, breaking of a transport conveyor belt and clogging of a charge device occur and, in a blast furnace, classification and segregation occurring in an accumulated ore bed, so that it is difficult to steadily use the heavy scrap without disturbing the operation of the blast furnace. If the light-weight iron scrap, which has been chipped, could be charged in a lump form into a blast furnace, a reducing furnace or the like as in the ore or sintered ore, the above-described problems associated with use in a blast furnace can be eliminated. However, no lumping method has hitherto been disclosed.
On the other hand, when scrap derived from galvanized steel sheets which occurs in a relatively large quantity, as such, is used in a blast furnace, fumy dust of ZnO occur in the blast furnace and accumulate on the surface of the furnace wall to form a deposit. For this reason, at the present time, the amount of zinc derived from ores and coke is limited to not more than about 0.2 kg/t-pig. For this reason, no attempt to directly use zinc-containing scrap in a high proportion in a blast furnace has been made in the art.
A schematic flow diagram of the conventional process for producing a sintered ore is shown in FIG. 1(a).
An ore as a main raw material, lime as an auxiliary material, coke as a fuel and return fines are taken off in respective amounts respectively from an ore hopper 1, a lime hopper 3, a coke hopper 2 and a return fine hopper (not shown), and water, for example, in an amount of 6.8% is added thereto in a granulator 4, and humidity conditioning granulation is effected to form a sintering material.
The sintering material containing 3.8% of coke is once charged into a raw material surge hopper 5, taken off from a drum feeder 6, charged through a chute 7 into a pallet 8 to form a packed bed 9. The thickness of the packed bed is 550 mm.
The coke on the surface bed portion of the packed bed is ignited in an ignition furnace 10 and burned while sucking the air downward to successively sinter the raw material from the upper bed towards the lower bed by taking advantage of the heat of combustion.
Further, there is a method wherein anthracite, which is more inexpensive than coke, is used instead of the coke.
Further, Japanese Unexamined Patent Publication (Kokai) No. 99635/1986 discloses a method wherein coke is dried to lower the water content of coke, thereby reducing the amount of coke used.
Further, Japanese Unexamined Patent Publication (Kokai) No. 274723/1988 proposes a method in which heat generated by prereduced iron having a high percentage metallization is utilized for sintering.
The prior art methods had problems including that use of coke as a heat source causes combustion of the coke to generate CO.sub.2 and NO.sub.2 which are unfavorable from the environmental viewpoint and the grain size of the sintering material is so small that the density of the p
REFERENCES:
patent: 2248180 (1941-07-01), Moriarty
patent: 3647417 (1972-03-01), Wetzel et al.
Aspects of sintering process with use of millscale from rolling mills in mix, Yu. G. Efimenko, et al., Apr. 16, 1986, vol. 16, No. 4, London, Great Britain, pp. 161-163 Steel in USSR.
Fujimoto Masami
Okuno Yoshio
Andrews Melvyn
Nippon Steel Corporation
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