Plastic and nonmetallic article shaping or treating: processes – Formation of solid particulate material directly from molten... – By vibration or agitation
Patent
1981-08-21
1984-01-31
Welsh, Maurice J.
Plastic and nonmetallic article shaping or treating: processes
Formation of solid particulate material directly from molten...
By vibration or agitation
425 6, B22F 908
Patent
active
044288948
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the production of metallic particles or granules. The invention is primarily directed to a method of production of metallic granules and extend to the products obtained in accordance with said method as well as to a device which is particularly well suited to the practical application of said method.
The invention is of general utility for the conversion of any metal into granules, this conversion principle being applicable not only to pure or practically pure metals but also to metallic compounds or alloys. The general aim of the invention is to obtain practically spherical grains having a diameter of the order of 0.1 to 5 mm, for example, thus forming in the aggregate a powder which has good flow capability, which can readily be conveyed by pneumatic means, which has relatively high bulk density and low porosity while also providing the possibility of obtaining uniform calibration of grains, if necessary after a sorting operation which is readily performed.
To this end, a molten metal bath must necessarily be employed at the outset. But the properties of metals, first in the liquid state, then during transition from the liquid to the solid state, and finally in the solid state, represent specific conditions such that the methods of granulation commonly employed in the treatment of products of another type such as products in paste form cannot be applied to these latter in a general manner. Furthermore, the methods of production of granules from molten metal baths which have been in use up to the present time do not yet prove satisfactory from the point of view of regularity of shapes and dimensions. In regard to methods related to the atomization process which it has been sought to apply to products having a base of reactive metals such as calcium, these methods produce reactive and hygroscopic powders which have poor storage stability and finally offer limited possibilities of use.
In order to overcome these disadvantages, the invention proposes a method of production of metallic granules of the type in which metal in the form of granules is solidified from the molten state. The method essentially consists in forming a jet of molten metal which is caused to pass through a vibrating orifice in order to divide the jet into individual drops and finally in causing solidification of said drops by cooling so as to form granules.
The method in accordance with the invention can be applied to the production of metallic granules from molten metal baths having any composition. However, it will be observed that, in the majority of instances, the metals being processed are in the molten state at a temperature within the range of 200.degree. to 1500.degree. C. and that the vibrating orifice through which the jet of molten metal is discharged usually opens into an atmosphere which is cooled by dissipation of heat in the surrounding air, the temperature of which can therefore be within the range of 20.degree. to 90.degree. C., for example. In practice, the operation is advantageously performed under conditions such that the temperature difference between the molten metal at the point of formation of the jet and the atmosphere into which the vibrating orifice opens is at least of the order of 200.degree. C. and preferably within the range of 300.degree. to 1300.degree. C., and more particularly within the range of 500.degree. to 1000.degree. C.
In accordance with a preferred mode of execution of the invention, the drops of the jet are caused to fall from the vibrating orifice under the action of gravity through an atmosphere of inert gas which is maintained at a temperature below the solidification temperature of the molten metal. The inert gas atmosphere may be chosen as a function of the nature of the metal, of the jet diameter and of the pressure conditions at the level of the vibrating orifice so as to ensure that the drops thus formed rapidly attain the maximum rate of fall over a height of fall which is made available in the atmosphere and is sufficient to permit complete solidific
REFERENCES:
patent: 2287029 (1942-06-01), Dowdell
patent: 2510574 (1950-06-01), Greenhalgh
patent: 4216178 (1980-08-01), Anderson
Anderson, Chem. Abstr., vol. 89, 11459/m, 1978, p. 322.
Extramet
Welsh Maurice J.
LandOfFree
Method of production of metallic granules, products obtained and does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of production of metallic granules, products obtained and, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of production of metallic granules, products obtained and will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2345031