US2061696A

US2061696A - Apparatus for making powdered metals

Info

Publication number: US2061696A
Application number: US627548A
Authority: US
Inventors: Bats Jean Hubert Louis De
Original assignee: Individual
Current assignee: Individual
Priority date: 1932-08-05
Filing date: 1932-08-05
Publication date: 1936-11-24
Anticipated expiration: 1953-11-24

Description

6 e O E y .T BM

w m i .m. M W 2 fi J. H. L DE BATS APPARATUS FOR MAKING POWDERED METALS Nov; 24, 1936.

Nov. 24, 1936.- DE Ts 2,061,696

APPARATUS FOR MAKING POWDERED METALS Filed Aug. 5, 1932 2 Sheets-Sheet 2 INVENT OR I'M 705M; laws I! 847:!

Qwm e L ATTORNEY-.7

Patented Nov. 24, 1936 UNITED STATES PATENT OFFICE I Jean Hubert Louis De Bats, East Orange, N. J. Application August 5, 1932, Serial No. 627,548

3 Claims.

This invention relates to improvements in methods and apparatus for preparing powdered metals and more particularly to a method involving the use of a centrifugal spraying machine 5 working in a gaseous atmosphere.

Hitherto, in the preparation of powdered metals, and more particularly high-melting and refractory metals generally it has been a custom to grind the material, with or without accompanying milling. Such a process is tedious, and, in addition, the physical characteristics of the metal are often changed due to burning on the wheel. In addition, foreign matter ground off the wheel during the course of the grinding operation finds its way into the powdered material and is required to be separated, usually a costly procedure. Other methods have involved the casting of metal inshot form, in well known shot towers. None of these methods have proved commercially practicable for the preparation of any appreciable quantities of powdered metals, and particularly of the harder metals, among which, for the purposes of this invention, iron is included,

together with its various alloys of any nature or 5 description.

In my prior application, Serial No. 601,101, filed March 25, 1932 for Method of making powdered metals, there has been disclosed methods and apparatus for preparing powdered metals in quanao y. 4 a

It has now been found that, by disposing the centrifugal casting or dispersing machine in a furnace or chamber having a desired spread of floor area and by maintaining an atmosphere of a gas in the chamber space and the centrifugal machine, desirable economies in production of powdered metals may be accomplished, together with the recovery of substantially pure particles which are unreacted at their surfaces. The gas 10 used may be a neutral gas, such as nitrogen, or it may be a combination neutral and/or reducing gas such as water gas, carbon monoxide, hydrogen and various hydrocarbon compositions including producer gas, natural gas- (raw or stripped), and ordinary illuminating gas. The particular gas used will be chosen according to its properties and the effect upon the metal under treatment.

As the temperature of the initially liquid metal particles thrown out by the centrifugal machine will decrease rapidlyin their trajectory, the question of the possible reaction ofsuch dispersed particles with the surrounding or circumambient gas will not be of particular importance, as a general proposition, a negative temperature gradient is not conducive to reactivity. Where the particles are to be maintained in any desired condition, the gas chosen for use may have sufficient reducing capacity so as to assure clean metal at all times.

Where metal compounds are to be formed, it may be found desirable to dissipate or disperse the particulate metal in liquid droplet form through an atmosphere of the vapors of the reacting compound. Such reactions may involve the 10 use of various organic and/or inorganic compounds in the vaporous state to react with metals. The process of the present invention is particularly adapted to such reactions, as well as to reactions not involving metallic components, due to 15 the fact that most reactions involving organic compounds proceed at a very slow rate, the rate being at least in part, a function of the particle size and surface area of the reacting materials.

' By dipersing one component in liquid particulate 20 form in an atmosphere of the other component, a maximum reactive surface is assured with corresponding increase in reaction speed.

The scope of the invention has been indicated in part only hereinabove, but it is not intended 5 to be limited thereto, as, as will hereinafter appear, the novel concepts of the present invention may include other specific modes of operation and apparatus for use in effectuating the same, as well as a widevariety of reacting materials. 3

In the drawings there is illustrated, by way of example, an apparatus which is suitable for use with the process of the present invention, and in which v Fig. 1 is a vertical section, partly in elevation, 35 of a centrifugal apparatus disposed in a chamber, and

Fig. 2 is a plan view, partly in section, of the floor of the chamber.

The casting apparatus comprises generally a 40 centrifugal member ID, mounted for rotation on a standard 20 and adapted to be motivated by a motor 30, supported on the standard 20 in any desired manner, as by a supporting shelf or table 2|. The motor shaft 3! passes through the 45 upper yoke 22 of the standard and is secured to a stud or boss H,'to which, in turn, is secured the bottom dished portion l2 of the centrifuge. The centrifuge is provided with an upper dished portion I3, having a central aperture, designated 50 generally by the numeral H. The halves of the centrifuge are spaced apart in any desired manner to provide a restricted peripheral aperture .or apertures l5, which may be of any desired width. A lining I 6 of any suitable refractory pouring aperture 42, to which is fitted a stopper 43, mounted on an insulated rod 44, which in turn is adapted to be lifted. up by means of a lever 45, fulcrumed on the support 46. This crucible arrangement is of the conventional bottom pour type and forms no part of the present invention, in and of itself, except in the combination herein shown and claimed. A stack or chimney 48, preferably of knockdown construction, may be disposed around the crucible so as to provide a blanket or atmosphere of gas therearound, which gas flows out of the chamber 50 through the central aperture l4 of the centrifuge proper, and also through the opening 54. By maintaining a sufllcient pressure of gas in the main chamber, any tendency of the centrifuge, when in operation, to suck in air from the outside will be overcome, so that the entire operation will be conducted in a desired gaseous atmosphere without access of air.

While a bottom pour crucible has been dis- 'closed as suitable for use in the practice of the present invention, it is not intended to be restricted thereto, as the desired results of the invention may be obtained by the use of lip pour crucibles and/or ladies.

The centrifuge assembly, as described, is adapted to be disposed in a furnace or chamber 50, of generally circular shape, having a top wall 5i of sheet metal such as heat resisting'iron or steel. The flooring 52 of the chamber may also be of sheet metal or may be made of fire proof magnesite brick or the like 53, arranged in any desired manner. The top and bottom walls of the chamber are thus spaced apart a distance slightly exceeding the height of the centrifugal member and forming a substantially flat radial chamber, the top'and bottom walls of which are apertured as indicatedat 54, 55 to permit the rotation of the centrifugal member. The upper member 5| may be provided with hinged portions 56, adapted to be folded outwardly away from the centrifuge in order to permit access to the latter for installation and/or repair. At its periphery, the chamber 50 may be provided with an apron 51, secured to the floor 52 in any desired manner, although it may be made demountable and in sections. A plurality of doors 58, hinged at 59, are configured to the aprons 51 and provide a peripheral channel or spout 60 into which the metal thrown by the centrifuge is adapted to be conducted downwardly into a container or .trough SI of any desired shape. The

spout or channel 60 may have a restricted outlet 62 to prevent undue escape of gas, as will appear more fully hereinafter. By raising the doors 58 upwardly, access to chamber 50 is permitted throughoutits entire extent and any powdered metal deposited on the floor 52 may be raked out into the collecting troughs 8|.

As intimated hereinabove, the chamber 501s adapted to be maintained or serviced with a gaseous atmosphere of any desired character. For this purpose, a plurality of radially disposed service pipes 10 having apertures II and connected with arms or -by-passes"l2, are provided underneath the floor, either in direct contact therewith or covered by courses of porousbrick, sand or other material, designated generally by the numeral 13. 1 Supply pipes 14, having control valves ii, are tapped into the pipes ii in suitable number to supply a desired amount of gaseous protecting and/or reacting fluid.

In operation, the valves 15 are opened and the air in chamber 50 driven out through apertures I4, 54, 55 and 62, and the chimney 44. When the chamber and the centrifuge have been cleared of air, the centrifuge is set in'motion and metal in the crucible 40 is dumped into the chamber of the centrifuge. This metal is immediately thrown out through the apertures ll through the chamber 50 into the spout 60 and then to the trough 6|. In its passage through the chamber 50, the metal is rapidly cooled by the circumambi'ent gas so that by the time the particles reach the delivery spout they are sufllciently cooled and will not be compacted. The gas used may be previously cooled to any suitable degree, if desired, in order to increase the temperature differential between the centrifuge I0 and the delivery spout 60.

The powdered metals recovered from the trough 8| may, after cooling, be removed to a ball mill, and ground to, a desired particle fineness. This subsequent grinding is enhanced by the relatively brittle condition of the material, as the quick chill produced in the chamber 5| imparts a desired hardness to the material and thus permits its ready disintegration without welding of the particles.

Any desired metal may be treated according to the process and apparatus herein disclosed and particular reference is had to the ferrous alloys of all types, including the high speed steels, as well as the low and medium carbon steels and,

in addition, the present invention comprehends the preparation of refractory materials such as tungsten, molybdenum and the like, together with their various compounds and alloys. In the preparation of these high melting compounds in powdered form, the crucible 40 may be made of graphite and enclosed in an induction furnace which-may be superposed directly over the aperture l4 so that the metal may be melted'in situ and in the presence of the reducing and/or, neutral gaseous atmosphere so as to prevent oxidation of the metal or compound being treated. The chamber 50 may be built on an earthen support or, as shown in Fig. 1, may be supported on standards 25. The chamber proper may have any desired dimensions and, for ferrous metals, a radius of 10 to 30' may be used. Owing to the speed with which the metal is thrown out by the centrifuge, any given installation may be expected to handle an appreciable tonnage without diillculty. For the preparation of smaller amounts, the size of the apparatus may be correspondingly reduced, due regard being had to the capacity of the metal or compound under treatment to set or freeze. By maintaining the metal in the crucible at a temperature but slightly above the freezing temperature, the diameter of the chamber 50 may be appreciably reduced, as it will be readily understood that, with hot metal, a greater cooling area or throw will be required than will be the case with metal which is held just above its freezing point.

As intimated hereinabove, the method and apparatus of the present invention is not only suited to the preparation of powdered metals, but also for the purpose of carrying out reactions of various types and particularly those involving, the formation of metallic compounds directly from the metal. Thus, in the preparation of the accuses in the crucible l and thrown into the chamber 55, which may be filled with chlorine gas, where the chloride is to be prepared, and bromine vapor if the-bromide is to be prepared.

Where organic or inorganic chemicals are to be used, they may be held in containers 80, disposed around the roof and heated in any desired manner, if necessary, in order to maintain the contents liquid. Valves 8| maybe provided to regulate the feed of the reagents. The chamber 50 may be maintained at any desired tem-- perature. Upon dispersing the molten metallic reagent, or any molten reagent, from the centrifuge HI into the chamber 50, the reagent fed from supply containers 80 will have an important and intimate contact with the enormous surface area exposed by the molten particles so that reaction should take place substantially immediately. By controlling the temperature of charm ber. 50 and of the reagents, any desired reaction may be carried out. The door and roof or the reaction chamber will be made of a material suited to the requirementsof the reaction. The dimensions of the chamber, as pointed out above, will ,also be adaptedto the particular requirements of the materials under treatment.

It will now be appreciated that there has been provided a novel method and apparatus for preparing metals in powdered form in which a gaseousreducing or neutral atmosphere is maintained in contact with the metal throughout, up to the time it is completely cooled, whereby undesirable surface reactions, oxidations, etc. are prevented and pure particulate metal is assured. In addition, the method and apparatus of the present invention have been shown to be suited for the preparation of metallic and other compounds which have hitherto been prepared with great diillculty.

While certain novel'ieatures or the invention have been disclosed and are pointed out in the annexed claims, it will be understood that vari= ous omissions, substitutions and changes may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is:

1. An improved apparatus for preparing metals having a high'melting point in powdered form, comprising in combination, a centrifuge, means for rotating the centrifuge, a circular, substantially flat chamber of relatively large diameter disposed around the centrifuge, the said chamber having top and bottom walls extending substantially radially from and adjacent to the top and bottom of the centrifuge, means for con= trollably supplying gas to the said chamber, and

means for supplying molten metals having a high melting point to the centrifuge, the said cen trifuge comprising a pair of dished members spaced to form a centrifuge chamber having a continuous aperture at the edges thereof, the upper dished member of the. centrifuge having a central aperture and the bottom member being provided with a boss co-axial with the aperture, said boss being adapted to receive the means for rotating the centrifuge.

2. An improved apparatus for preparing metals having a high melting point in discrete form, comprising, in combination, a container for molten metal, a centrifuge coaxially disposed beneath said container, a circular, substantially flat chamber surrounding said centrifuge, the said chamber having top and bottom walls extending substantially radially from and adjacent to the top and bottom of the centrifuge, a peripheral apron for said chamber, doors coac'ting with said apron to form a continuous discharge channel, and means for supplying a gaseous atmosphere to said chamber and associated cen-= trifuge, the said centrifuge comprising a pair of dished members spaced to form a centrifuge chamber having a continuous aperture at the .edges thereof, the upper dished member of the centrifuge having. a central aperture and the bottom member being provided with a boss coaxial with the aperture, said boss being adapted to receive the means for rotating the centrifuge.

3. An apparatus for preparing metals having a high melting point, in discrete form, compris ing, in combination, a container for molten metal, a peripherally apertured centrifuge c0=- axially disposed beneath said container and forming a revolving chamber, a fixed chamber enclosing the centrifuge, the said fixed chamber having top and bottom walls extending substan= tially radially from and adjacent to the top and bottom of the centrifuge, the radial extent of the fixed chamber being of the order of ten to thirty feet, a peripheral apron for said chamber, doors coacting with said apron to form a continuous discharge channel, and means for supplying a gaseous atmosphere to said chamber and asse ciated centrifuge, the said centrifuge comprising a pair of dished members spaced to form a centrifuge chamber having a continuous aperture at the edges thereof, the upper dished member of the centrifuge having a central aperture and the bottom member being providedwith a boss co-axial with the aperture, said boss being adapted to receive the means for rotating the centrifuge.

JEAN HUBERT LOUIS DE BATS.