Powder metallurgy processes – Forming articles by uniting randomly associated metal particles – Consolidation of powders
Patent
1995-07-07
1997-05-13
Jordan, Charles T.
Powder metallurgy processes
Forming articles by uniting randomly associated metal particles
Consolidation of powders
419 66, 75755, 75758, 75759, B22F 100
Patent
active
056302029
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method for making sponge iron briquettes from fine ore with a maximum grain size of less than 2 mm, preferably less than 0.5 mm, wherein hot fine ore is fed to a roller press and briquetted by opposite briquette pockets of the roller press to form sponge iron briquettes and wherein during briquetting fine ore which is compacted by one of the separating webs between the briquette pockets, and fines in the form of dust are produced, the materials being separated as returns from the iron sponge briquettes and fed to the fine ore prior to briquetting, the mean grain size of the fine ore being smaller than the mean particle size of the returns.
In the prior art fine ore has normally been formed into pellets prior to hot briquetting. During briquetting sponge iron briquettes and returns are obtained, the returns being again fed to the pellets above the roller press.
Moreover, a single installation has become known in the prior art for directly pressing fine ore into its resultant particulate form. In this method the returns are collected and then fed to the fine ore prior to briquetting. This method, however, has not turned out to be very successful in practice and has not been accepted.
SUMMARY OF THE INVENTION
It is therefore the object of the present invention to improve a method for making sponge iron briquettes from fine ore in such a manner that the briquetting operation can be performed substantially without any trouble.
The object is attained according to the invention in that the returns are fed to a conveyor system after having been separated from the sponge iron briquettes and the returns which are still hot are fed by the conveyor system substantially evenly and continuously to the hot fine ore to be still briquetted.
Although it is known that returns are continuously fed during the briquetting of pellets and/or lump ore, this is a pure recycling measure which has no effect on the processing of the pelletized fine ore.
In comparison therewith, the invention has the advantage when particulate fine ores are processed that the flow of returns fed into the fine ore has a substantially uniform temperature and provides a uniform quantitative portion. The fine ore is then evenly coarsened by the continuously fed returns, which is conducive to an improved briquetting capacity. The pelletizing step which is normally considered to be necessary before the processing of the fine ore can entirely be dispensed with due to the present invention, since the characteristics of the fine ore can be influenced through the uninterrupted supply of returns. Moreover, the returns can respectively be returned at a temperature which can be chosen within a specific temperature range and depends on the speed of the transportation system. This avoids, in particular, thermal variations within the material to be processed, such variations possibly leading to an over-load on the roller presses. Hence, the service lives of the roller press are considerably increased, which in the final analysis reduces costs.
It is also advantageous when the sponge iron briquettes and the returns fall into a vibration drum or a rotation drum after briquetting for separating returns and sponge iron briquettes substantially entirely. Such a procedure is especially of advantage when the sponge iron briquettes are pressed with fixed briquette rolls which permit a relatively thin briquette seam, whereby the briquettes and the returns can be separated from one another by a relatively simple vibration drum or rotation drum. Furthermore, it is advantageous when the sponge iron briquettes and the returns are conveyed from the vibration drum or rotation drum to a vibrating screen which separates sponge iron briquettes and returns from one another. After the sponge iron briquettes and the returns have been separated from one another by the vibration drum or rotation drum, it is relatively easy owing to a simple vibrating screen to separate the two parts from one another.
The fine ore can be proc
REFERENCES:
patent: 2799573 (1957-07-01), Barnett et al.
patent: 3627288 (1971-12-01), MacDonald
patent: 3647417 (1972-03-01), Wetzel et al.
Chi Anthony R.
Jordan Charles T.
Maschinenfabrik Koppern GmbH & Co. KG
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