US1856679A

US1856679A - Apparatus for comminuting metals

Info

Publication number: US1856679A
Application number: US45284A
Authority: US
Inventors: Arry M Williams; Victor W Bihlman
Original assignee: General Motors Research Corp
Current assignee: General Motors Research Corp
Priority date: 1925-07-22
Filing date: 1925-07-22
Publication date: 1932-05-03
Anticipated expiration: 1949-05-03

Description

.May 3, 1932. H. M. WILLIAMS ET AL 1,856,679

APPARATUS FOR COMMINUTING METALS Filed July 22, 1925 2 Sheets-Sheet 1 Ill-mm 4| x 40 J I 4 l I l I 5 I WI um ZQL I Wm M- May 3, 1932. H. M. WILLIAMS ET AL 1,856,679

APPARATUS FOR COMMINUTING' METALS 2 Sheets-Sheet 2 Filed July 22, 1925 Patented May 3, 1932 UNITED STATES PATENT OFFICE ABBY M.,WILLIAMS AND VICTOR W. IBIHLMAN, OF DAYTON, OHIO, ASSIGNORS TO GENERAL'MOTORS RESEARCH CORPORATION, A CORPORATION OF DELAWARE APPARATUS FOR COIIIIMTNUTING METALS Application and July 22,

This invention relates to the comminuting of metals of relatively high melting point, by atomizing them while in a molten condition, by a stream of aeriform fluid under pressure.

I It hashitherto been proposed to atomize metals of relatively low melting point by melting them, letting the molten metahflow through a nozzle and forcing a stream of air or steam into contact with the stream of molten metal. This process has been commercially practiced with lead, tin and other metals of relatively'low melting point. So far as I am aware, metals of high melting point,such as copper, nickel and the like, have never been commercially produced by this method.

It is an object of this invention to produce metallic powders of copper, or other'highmelting-point metals, by atomization.

The invention consists in the method-of atomizing high-melting-point metals, and in an apparatus for carrying out this method, as more fully described hereinafter, illustrated in the accompanying drawings, and defined in the appended claims.

In the drawings, in which like reference characters indicate. like parts throughout the several views:

Fig. 1 is an elevation, partly in section, of an apparatus adapted to practice the process of this invention;

Fig: 2 isca sectionthrough a fragment of a furnace, crucible and atomizin'g nozzle, forming part of the invention; Fig. 3 is a section of a fragment taken on the line 3-3 of Fig. 2, looking upward towa'd the bottom of the furnace and crucible; an

Fig. 4 is a view similar to Fig. 3. showing a modification in the relation of the inlet pipes to the'atomizing nozzles.

In Fig. 1, 10 indicates afurnace which may be of the combustion type, fed bycombustible gas through a pipe 11. A removable cover 12 normally closes the upper end of said furnace, this cover may have a hole in it (not shown) for receiving a funnel by means of v which to guide molten metal into a crucible disposed in the interior thereof, as will be explained presently. The furnace 10 has an 1925i Serial No. 45,284.

expansion space in a large pipe 13 beneath it. Pipe "13 is closed at its upper end excepting that it has an opening registering with the opening in the furnace. The pipe 13, as shown in Fig. 1, curves to one side at 14, and enters the lower portion of a large collection chamber lo'having an inclined bottom 16, a top 17 which is open to the atmosphere, preferably through a fine-meshed fabric to pre-' vent metallic dust leaving the chamber 15 through the top. At the lower end of the inclined part 16, there is a door 18, through which copper or other metallic powder, produced by the atomizing process to be described, may be removed.

The furnace 10 may be built up of fire brick 19, or other refractory material, within a shell of metal 20, and may be supplied with combustible gas through pipe 11 at any suitable point, preferably just above the ledge 19a, which may be formed of fire clay, or the like. The ledge of fire clay (19a is of annular form, the opening in it being lined with a collar21 haying, an internal flange 22. The

opening within the flange 22 of said collar 21 is occupied by a bottom member 23, having a flange 24, resting upon the flange 22. Said bottom member 23 has a central hole 25 and one or more smaller holes 26, arranged around it. The collary2l and the bottom member 23 may be made of cast iron, or preferably of some suitable high-heat-resisting material, such as nichrome.

' Resting within the furnace 10 is a crucible 27 made of any of the usual materials adapted for the purpose, such as graphite. In the form shown in Fig. 2, the crucible 27 has an extension 28 of the same material, which is screw-threaded'into the bottom of the crucible, as at 29, or may also be integral with it.

The extension 28 tapers downward and the lower end rests upon the bottom plate 23,. said extension having an opening in itslower end registering. with the opening 25. Into the lower end of extension 28, there is secured,

as. bykzrewthreads 30, a graphite nozzle 31 which has atapering lower end protruding some distance below the extension 28, and an upper end extending some distance up into said extension. 1ne lower tapering end of the nozzle is pierced to receive a tube 32 made up of any suitablematerial, as quartz or lavite, said tube being suitably secured in place. Above the quartz tube the graphite nozzle is counterbored as at 33, the upper end of the counterbore being closed by a cap 34, also of graphite. The walls of the graphite nozzle 31 are perforated as at 35, to form passages for the entrance of molten metal from the crucible into the nozzle. of the presence of passages 35 the nozzle acts as a strainer to prevent the entrance into the nozzle of dross, slag, or other coarse material, which might act to clog the quartz tube 32.

The lower end of nozzle 31 protrudes some little distance below the lower side of the furnace, through the opening 25 in the bottom plate 23. This end of the nozzle is encased by a shell 36. of heat-resistant metal, to mechanically strengthen the graphite and pre vent burning. urroundihg the protruding end of the nozzle, is an annular nozzle for receiving aeriform fluid under pressure, such as air, and discharging it in a converging stream, annular in cross-section, around the exit of the quartz tube 32. This annular nozzle will be termed, for convenience, an air nozzle. The main part of the air nozzle is indicated in Fig. 2 by the numeral 37. The inner part of it comprises a shell 38 which conforms, interiorly, substantially to the shell 36, but is spaced slightly therefrom in order that there may be no binding because of warping orexpansion due to heat. The said

members

36, 37 and 38, should be of highheat-resisting metal, and we have found that an alloy known commercially as Resistal, is well-suitedfor the purpose. Tapped into the member 37 of. the annular air nozzle, are pipes 39 leading from -a source (not shown) of air, or other suitable gaseous material, under pressure. The air nozzle may be secured. in place by any suitable means, iron bolts 40, as shown in Fig. 2, answer the purpose very well; although they may have to be replaced occasionally, owing to the de-' structive effect of heat to which they are subjected.

Surrounding the air nozzle and secured to the bottom plate 23, by said bolts 40 and nuts 41, is a casing 42 made of sheet metal of suitable high-heat-resisting material, which mav be Besistal, or a metal known commercially as Ascoloy. Pipes 39 penetrate the wall of the casing 42 and fit snugly therein. When the casing 42 is in place, it is in com- -munication with the interior of the furnace within the furnace 10, products ofcombus tion will enter the chamber within the casing some of the products of combustion may pass Because fluid to issue from the annular orifice 44 in v a whirling state. In Fig. 4the air-conducting pipes 39a are shown disposed tangentially to effect increased agitation of the stream of molten metal where the air acts upon it.

In the practice of this method, copper or other relatively high-melting-point metal is brought to a state of fusion in any suitable way. The furnace 10 is preheated to a high degree of heat by starting combustion therein well in advance of the time of filling the crucible 27 with the molten metal, so that the crucible is heated to a high temperature and products of combustion circulating around the nozzle portions exteriorly of the furnace, said nozzle portions are also preheated to a relatively high temperature, say, from 1600 to 2000 degrees Fahrenheit, more or less. When crucible and nozzles have been brought to the required temperature, the molten metal heated in another furnace is conducted to the heated crucible 27. From said heated crucible, the molten metal flows through the small passages 35 into the interior of the nozzle 31 and thence passes, free from dross or slag, into and through the quartz tube 32. While the molten metal is issuing from the quartz tube 32, the atomizing fluid is forced by pipes 39 into the annular nozzle and out through the annular opening 4.4.beyond which the end of the quartz tube 32 protrudes slightly. The atomizing fluid takes an inverse conoidal form, surrounding the stream of molten metal, which falls substantially into the'apex of the cone. This stream has an entraining action tending to withdraw molten metal from the crucible. The impact of the atomizing fluid and the sudden expansion of it, as it loses its force in the large expansion space afforded by the pipe 13,

breaks up the stream of metal into fine particles, which fall down the pipe and progress toward the door 18. The powder of copper and other metals thus produced. mav be swept from the walls of the pipe 13, and the chamber 15, and collected adjacent the door 18. from which it may be removed.

It is found in the treatment of c per, that a large proportion of the powder, approximately 75%, is of a size to pass through H 2OO -mesh sieve, and that the powder of this 42, circulate around the nozzles, and that.

fineness is pure copper, substantially free from oxide,"while the coarser partlcles are found to be oxidized, more or less, and not usable where pure copper powders are needed, as in the manufacture of bushings, brushes. and the like.

While the form of embodiment of the invention as herein disclosed. constitutes a preferred form. it is to be understood that other forms might be adopted, all coming within the vscope of the claims which follow.

What is claimed is as follows:

1. Apparatus for producing metallic powders of relatively high-meltingpoint metals comprising. in combination, a furnace, a crucible in which the metal is melted, a nozzle connected with the crucible and extending outside the furnace, means for directing the ga eous products of combustion from said furnace around the discharge end of the nozzlc to maintain the nozzle at a relatively high temperature and means for subjecting the metal issuing from the nozzle to a whirling stream of aeriform fluid under pressure and causing the products of combustion to flow around the part of said nozzle outside the furnace.

2. Apparatus for producing metallic powders of relatively high-melting-point metals comprising. in combination, a furnace, a crucible in which the metal is melted. a nozzle connected with the crucible and extending outside the furnacemeans for directing the gaseous products of combustion from said furnace around the discharge end of the nozzlc to maintain the nozzle at a relatively high temperature and means for subjecting the metal issuing from the nozzle to a hollow stream of aeriform fluid under pressure surrounding said nozzle and causing the products of combustion to flow around the part of said nozzle outside the furnace.

3. The combination of a furnace having an opening. a crucible disposed within the furnace. a nozzle connected to the crucible extending through said opening, said nozzle having perforations adapted to function as a strainer of the metal entering the nozzle, and means for atomizing the metal issuing from the nozzle by a stream of aeriform fluid under pressure.

4. The combination of a. furnace having a bottom plate provided with an orifice, a crucible disposed within said -furnace, a nozzle connected to the crucible and extending through the orifice in sa d plate. means for atomizing the metal issuing from said nozzle, said means and nozzle being encased within a casino: which communicates with the interior of the furnace and has an opening with which the atomizing orifices register.

5. Tu means for atomizinc; metals. a cruih e having a graphite nozzle provided with a quartz exit tube.

6. Tu means for atomizing metals, a cruible having a graphite nozzle projecting some distance into the crucible and having signatures.

HARRY M. WILLIAMS. VICTOR W. BIHLMAN.