Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1998-12-21
2000-06-13
Wyszomierski, George
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
241 2425, B02C 1700
Patent
active
060744561
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
This invention relates to a process of hot briquetting granular sponge iron, where the granular sponge iron is supplied to a roller press at temperatures of 600 to 850.degree. C. for moulding the hot briquets, and there is produced a strip structure of sponge iron by means of formed hot briquets, which are arranged at a distance from each other, from which strip structure the hot briquets are separated by smashing said structure, so that fragments of the strip structure are obtained.
A known process of this type is described in the U.S. Pat. No. 5,082,251. The hot briquets moulded by means of the roller press are directly charged into a rotary drum in the hot condition. As a result, the rotary drum is subjected to a high wear.
It is the object underlying the invention to perform the production of the hot briquets at low cost and with little equipment involved, where in particular the wear and the susceptibility to failure should be kept as small as possible. In accordance with the invention, this object is solved in the above-stated process in that upon smashing the strip structure the hot briquets and at least part of the fragments are cooled to temperatures in the range from 20 to 400.degree. C., and preferably not more than 200.degree. C., that the cooled briquets and fragments are passed through a rotary drum, where the briquets and the fragments produce fine-grained fines, and that the fines are separated from the briquets and fragments.
Granular and in particular fine-grained sponge iron is very pyrophoric, so that it can only be employed under a protective gas atmosphere. A useful protective gas is, for instance, nitrogen or carbon dioxide or a mixture of these inert gases. When the granular sponge iron has been briquetted, it is no longer or hardly pyrophoric, and the handling of the briquets and their storage are very much simplified. At temperatures of 600 to 850.degree. C., and for instance in the form in which the sponge iron comes from a reduction plant, the same can be moulded in a known manner to form hot briquets by means of a roller press. There is produced a strip structure of sponge iron with attached hot briquets arranged at a distance from each other. This strip structure is subsequently smashed, in order to separate the hot briquets from each other, so that fragments of the strip structure are obtained. When these fragments are large enough, it is expedient to process them together with the hot briquets.
The sponge iron suitable for the process can be produced in any kind of known iron ore reduction plant. The sponge iron usually has an Fe content of 90 to 98 wt-%.
In the process in accordance with the invention it is important that the hot briquets and the fragments are cooled before they are introduced into the rotary drum. By means of this cooling it is avoided that hot material is charged into the drum, and that the rotary drum must be designed for processing such hot material. For the wear in the drum turned out to be very high when hot material having temperatures above 400.degree. C. is charged into the rotary drum, and the rotary drum must be repaired frequently. Due to such frequent repair it is necessary to have a substitute rotary drum available, when a continuous production of hot briquets is desired. The process in accordance with the invention, on the other hand, has the advantage that only cooled material is supplied to the rotary drum, so that less wear is applied on the drum and the operation need only rarely be stopped for repair. At the same time it is now possible that the cooled material need not be stored temporarily in a container under a protective gas during the repair of the drum, and that the material can be supplied to the rotary drum when the repair has been terminated. In this case a substitute drum is not required.
Embodiments of the process will now be explained with reference to the drawing, wherein:
FIG. 1 represents the flow diagram of the process,
FIG. 2 shows the strip structure of the sponge iron coming from the roller press in an ele
REFERENCES:
patent: 3556772 (1971-01-01), Rausch et al.
patent: 4033559 (1977-07-01), Pietsch
patent: 4057978 (1977-11-01), Sato
patent: 4076520 (1978-02-01), Pietsch
patent: 4165979 (1979-08-01), Sanzenbacher
patent: 5082251 (1992-01-01), Whipp
Patent Abstracts of Japan, vol. 9, No. 21 (C-263), Jan. 29, 1985 Abstract of JP 59170213.
Freytag Jochen
Hausmann Helmut
Hirsch Martin
Schimo Siegfried
Stroder Michael
Metallgesellschaft Aktiengesellschaft
Morillo Janelle
Wyszomierski George
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