Specialized metallurgical processes – compositions for use therei – Processes – Electrothermic processes
Patent
1984-08-10
1987-03-10
Lieberman, Allan M.
Specialized metallurgical processes, compositions for use therei
Processes
Electrothermic processes
75 5, C22B 100
Patent
active
046489002
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for producing a charge of high permeability and stable structure on a mobile suction-sintering grate or in a stationary or mobile suction-sintering pan, comprising the steps of compacting a moist material mixture to be sintered, preferably between at least one pair of pressure-loaded rolls, to form a coherent cake, the particles forming said cake being held together mainly by capillary forces, and breaking the cake into pieces of a size suitable for forming a suction-sinter charge. The invention also relates to apparatus for carrying out the method.
Suction sintering is primarily applied to the purpose of agglomerating finely divided iron-oxide material into a form suitable for charging to a blast furnace, and represents a substantial cost in the manufacture of crude iron. Consequently, it is important that as much sinter as possible is produced per each unit of grate area, in order to reduce investment, maintenance, fuel and electrical-energy costs.
With regard to sintering capacity, the most important factor is the permeability of the charge. The more gas drawn through the charge per unit of time, the less time required to effect a satisfactory sintering operation. The permeability of the charge can be increased in a number of ways. The most usual method in this respect is to increase the amount of coarse particulate return-sinter admixed with the charge. Large quantities of coarse return-sinter, however, increase the amount of fuel required per unit of weight of final sinter, and incur additional handling costs. Furthermore, in certain instances it is necessary to crush the final sinter, in order to obtain the requisite amount of return-sinter. Another method often used is one in which the charge mixture is subjected to a subsequent rolling process in a drum. Although the permeability of the charge is increased to a certain extent by this method, it is necessary to control accurately the amount of moisture present, and normally the amount of water needed is more than is justified by the thermal progress of the sintering operation at the desired low level of fuel consumption. Neither does rolling a mixed charge in a drum produce a stable charge. Instead, the charge produced tends to become compacted when subjected to the high underpressure desirable in suction sintering operations in respect of high plant capacity, when sintering fine, particulate material.
In a number of cases attempts have been made to increase the permeability of the charge by micro-pelletizing one or more of the iron-oxide products making up the charge. However, this technique requires the provision of additional and expensive pelletizing apparatus, such as drum or pan pelletizers. Only extremely fine-grain material can be micro-pelletized, and normally it is necessary to use a binder, together with an accurately controlled addition of water, which may result in bogging in the lower regions of the charge during the sintering process, i.e. the mutual adhesion of respective particles in the bottom region. Another drawback is that the charge constituents are not mixed together with a thoroughness sufficient to favour desired formation of slag during the sintering and blast-furnace operations.
In many parts of the world, iron-oxide is highly enriched in order firstly to increase the iron content and secondly to remove contaminents, such as phosphorus. In such working-up processes, prior to being enriched the ore must be ground down to such a small particle size as to render the resultant fine concentrate unsuitable for suction sintering. Examples of such concentrates include the Mid-Swedish and Northern-Swedish concentrates which have been purified of phosphorous and which are thus very fine. In order to find a market for such materials, it has been elected to sinter them to pellet form. Sintered pellets, however, are not ideal agglomerates for treatment in blast furnaces, neither with respect to shape nor chemical composition, and in many instances the sinter obtained from suction-sintering proc
REFERENCES:
patent: 3353953 (1967-11-01), Schwarz
patent: 3432287 (1969-03-01), Greaves et al.
patent: 3837843 (1974-09-01), Pons et al.
patent: 3986864 (1976-10-01), Hofmann
patent: 4084957 (1978-04-01), Ernst
patent: 4199348 (1980-04-01), Ground
patent: 4199349 (1980-04-01), Wood et al.
patent: 4317676 (1982-03-01), Souma et al.
Ball et al., Agglomeration of Iron Ores (1973), pp. 259-265, Amer. Elseirs Publ. Comp., N.Y.
Bostrom Olle
Gorling Karl
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