US2358068A - Process for the production of comminuted particles - Google Patents

Description

Sept. 12, 1944. s. HILLER 2,358,068

PROCESS FOR THE PRODUCTION-OF COMMINUTED PARTICLES med Jan. s, 1941 ATTORNEY Patented Sept.y 12, 1944 UNITED STATES 4PATENT .OFFICE PROCESS FOR THE PRODUCTION F COMBIINUTED PAR'IICLI'JS.

Siegfried` Hiller, New York, N. Y. Application January 3, 1941, Serial No. `372,980 l 5 Claims;k

This invention relates to a process and-apparatus for the production of comminuted particles, in particular particles of metallic: oxides and related products, and includes correlated improvements designed to enhance the utility of such apparatus.

In my U. S. Patent No. 2,213,365 issued September 3, 1940, entitled Apparatus for the production of powders of low-melting-point metals or of compounds thereof, I have described an apparatus including an atomizing chamber for producing flnely comminuted metallic particles. comminuted metallic particles which are thus formed pass directly into an oxidizing chamber where the lighter particles become oxidized and are drawn oil', While heavier particles fall back into the atomizing chamber.

It has now been found desirable to provide a process and apparatus for forming comminuted metallic particles of substantially uniform size and diameter by providing for the disposal of the larger non-uniform particles formed during the operation. It has also been found desirable to providel in such an apparatus means for separating the heavier particles from the smaller particles and at the same time avoiding the direct return of such heavier particles to the comminuting apparatus.

It is also desired to provide means for combining the smaller uniform metallic particles with various gaseous reagents to form compounds or derivatives thereof and collect the same in a finely divided comminuted state.

It is a general object of the present invention to provide a process and apparatus for the production of finely divided comminuted metallic particles, oxides, or other compounds in a continuous operation.

It is a specic object of the present invention tov jects will in part be obvious and will in part appear hereinafter.

In carrying out the present invention it might be considered in its broadest aspects .as comprising two distinct embodiments.

vIn general, the process comprises comminuting molten metal, projecting the comminuted particles into an atmosphere spaced from the point of comminution so that larger particles fall by gravity and are deposited at a point other than 'that of the point of comminution. v v In one embodiment the process comprises melting a mass of metal, atomizing a portion thereof, separating-the larger particles from the'smaller particles thus atomized, finally collecting the smaller uniform particles while returning the larger particles to the original mass of molten metal.

A second embodiment of the invention contemplates further treatment of the finer particles,

comprising chemically reacting such particles `with various reagents to form compounds thereof,

and collecting such compounds in a substantially ilnely divided comminuted state.

In an apparatus suitable for carrying out the present invention there -is provided means for melting a low melting-point metal, means for comminuting said metal to form comminuted metallic particles thereof, means for separating the heavier particles from the smaller and lighter particles thus formed, means for returning said heavier particles to the molten metal, and means for collecting the lighter particles in a ilnely divided state. l According to the present invention, there is also provided in an apparatus for the production of v comminuted metallic vparticles orcompounds thereof, a vessel in which metal may be melted, a comminuting unit comprising a. rotatable ilinger wheel, a casing for said flinger wheel, 'an inlet in the bottom of said casing for admitting aportion of molten metal from the melting vessel, an outlet for said casing comprising a side duct and a combustion chamber connected to said side duct, means for producing comminuted metallic particles in said comminuting unit and conveying said particles into the combustion chamber, collecting the lighter particles thus formed while returning the heavier particles to said reservoir.

In a preferred embodiment there is also providedwithin said combustion chamber a reacti n 'z one for forming pure metallic particles, the tallic oxides, or various s other chemicalx compounds thereof, as said finer comminuted particles are being passed through said chamber.

Various low melting-point metals which may be employed to form comminuted metallic particles comprise such metals as lead, tin, antimony, zinc,

y metals in the comminuted state to form various compounds thereof comprise various reactive gases or vapors, such as air, steam or oxygen which form metallic oxides, sub-oxides, and the like. Other reactive gases such as chlorine, bromine, iodine, hydrogen sulfide, sulphur, carbon dioxide and the like may be used to form halides, suldes, carbonates and other compounds with the comminuted metals. Mixtures of these various gases may be used to form other derivatives of the metallic particles, and which also may depend upon operating conditions, such as temperature, pressure and the like.

Alternatively, suitable inert gases may be emv ployed toprevent the formation of compounds or derivatives of the various metals, for example, such gases as helium, carbon monoxide, nitrogen, and other inert gases. Such gases may be used to create an inert atmosphere to provide for the formation of comminuted metallic particles in a substantially unreacted state. Under other cond-itions hydrogen may be employed either as a reactant to reduce metallic compounds-which may be formed, or to initially prevent the formation of such compounds. i

A suitable comminuting unit comprises such unit as described and set forth in my aforesaid U. S. Patent No. 2,213,365 and which will be described in detail hereinafter.

For the combustion chamber there may be-employed any of a wide variety of furnaces, burners or ovens which are used to burn the various atomized or vaporized combustibles such as gases, fuel oil, powdered coal, coke dust, and the like. In a preferred embodiment there is provided a modied combustion chamber adapted to burn a gas, or to provide other means for initiating a reaction between various gaseous reagents and the comminuted metallic particles causing them to ignite or otherwise combine to form compounds thereof. Alternatively, other materials such as inert gases may be introduced to prevent the formation of such compounds. Y,

The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others, the apparatus embodying features of construction, combinations and arrangement of parts adapted to effect such steps, and the product which possesses the characteristics, properties and relation of constituents, all as exemplified in the detailed disclosure hereinafter s, et4 forth and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to vthe following detailed description taken in connection with the accompanying drawing, in which: l

Fig. 1 is a view of a section in elevation of one form of apparatus suitable for carrying out the means of conduit I3 and utilized to preheat atomizing chamber I5.

The atomizing chamber I5 comprises a housing belt (not shown).

gases formed in furnace I0 may be drawn o by or casing I4 which is preferably of an insulated type having a thick wall. In the bottom of said atomizing chamber there is provided one or more openings I1 to which there are attached tubes I8, which permit a portion of the molten metal I2 to enter the comminuting chamber by gravity flow. There is provided in said atomizing chamber a flinger wheel I6 adapted to rotate within the atomizing chamber and which may be rotated by shaft 20. The shaft may be driven by any suitable driving means, such as by being coupled directly to an electric motor or to a pulley and One side of the atomizing chamber `I5 is provided with an outlet duct I9 which is in turn connected with combustion cham ber 2 I, the lower portion 22 of said chamber dipping into the surface of molten metal I2. Within the combustion chamber 2| there is provided a plurality of jets or tuyres 23 substantially near the central portion of said chamber, which jets are adapted to burn a light fuel, gas or oil if initial heat is found desirable or necessary. In the preferred embodiment a combustible fuel or gas, such as water gas, hydrogen sulfide, or a halogen may be introduced by means of supply pipes 24, and the jets 23 supplied with a suitable gas, such as air or oxygen, by means of pipes 26. Alternatively, a spark gap may be used in place of the flame jets; or reacting gases such as chlorine, hydrogen sulfide, and the like may be admitted by means of the jets to form various metallic derivatives of the comminuted metallic particles; or such jets may be used to introduce an inert gas. The air or other gases may be preheated by passing pipes 26 through preheaters 21 comprising fire-brick surrounding the combustion chamber and arranged about the reaction zone 3|.

Combustion chamber 2| is shown as having a constriction 3'I near the top portion, so that comminuted particles which are carried upwardly from reaction zone 3| may be drawn off and/or burned in secondary burning zone 33. An excess volume of air may be admitted to the secondary burning zone 33 by a draft created between dome 34 and collar 35, which draft intake is shown by direction arrows A. If desired, incomplete combustion reactions may be conducted with the metallic particles to form sub-oxides of the metals, or a mixture of pure metallic particles and oxides thereof, or other various derivatives, by lowering or raising the dome 34 to admit larger or smaller volumes of air, as required. Alternatively, the dome may be lowered all the way, whereupon the dome makes a tight fit with collar 35, thus excluding air entirely. Thus air may be excluded entirely from zone 33 when lt is desired to form the metal in comminuted metallic form, or when it is desired to form the sulfldes, chlorides, carbonates or metallic `deriva tives of the metals other than the oxides. The particles may be drawn off by suitable known means, such as by means of a draft created by a suction fan or blower attached -to neck 32 (not shown).

Referring to Fig. 2, a portion of the combustion chamber is broken away to show the flinger wheel I6 within casing I4 and to show its relationship with the combustion chamber 2|. Particles of the comminuted metal are carried upwardly through the reaction zone 3|, which zone may be supplied -with suitable gases by means of the jets 23 as described. The heavier particles formed during the comminuting process and which are carried into the vertical chamber 2| are permitted to drop into the vessel Il by gravitational differoff or omitted entirely.

assaoee venting direct return o! the heavier particles to the atomizing chamber.

In carrying out the process of the invention. a suitable quantity of metal is melted in the melting vessel or reservoir," and after suihcient heating a quantity of the molten metal'is intro.- duced by gravity flow into atomizing chamber I where it contacts the ilinger wheel IB. The ilinger wheel is rotated within the atomizing chamber at a velocity suitable to create a mist comprising particles of said molten metal. The majority of the particles thus formed iind their way or are driven out of the atomizing chamber through side duct |9-and into combustion chamber 2 I. It will be noted that vside duct I9 is closecoupled with the combustion chamber 2| in order to facilitate the passage of the comminutedpar ticles from the'atcmizlng chamber into the lower part of thecombustion chamber.' A portion of the heavier particles formed during the atomizing process strike the inner wall 2S oi said chamber and drop directly into reservoir containing the molten metal. Other heavier particles which may be carried along with the finely comminuted particles gradually drop back into the reservoir il as the nner particles continu their upward travel through the combustion zone 3|,

where they may be ignited to form the various comminuted metallic oxides or other compounds. Alternatively, the ignition jets 23 may be used to introduce an inert gas or they may be closed In many cases after the metallic particles have been ignited for a short period of time and after a suillcient temperature has been so maintained, the initial supply oi fuel or gas introduced by jets 23 may be cut ofi:` and the burning of such metallic particles sustained by merely introducing into the combustion chamber an adequate supply of prei heated air by means of supply pipes 26. Furthermore, other metallic particles, such as those formed of zinc or tin,.may become ignited and burn without the necessity of pre-ignition to initiate the combustion.

In a modification of the apparatus, a horizon- I tal combustion chamber may be substituted for the vertical combustion chamber illustrated in Fig. 1, and blowing means may be utilized to disperse the comminuted particles through such combustion chamber operated in conjunctionv with "the projecting means. k

The following exampleis given by way of illustrating the process of the invention, but -is not to be interpreted in a limiting sense.

Substantially pure lead metal is melted in the melting vessel in quantity suilicient to flow into th'e atomizing chamber I5 by means of open-A ings I1 and contact the flinger wheel I6. The

is provided a striking plate formed of heavy metal removably attached to the inner wall 2! which may be replaced from time to time as required. The remaining comminutcd metallic particles are carried upwardly through the cornbustion chamber, and leave the combustion chamber by means of the constricted portion 21 and are carried away by a reduced pressure `created within the dome 3l. 'As the particles travel upwardly through the combustion chamber 2| the remaining heavier lead particles are separated from the iinely comminuted particles iiinger wheel is rotated at a velocity suiiicient to create a mist comprising a plurality of comminuted particles of molten metal within the atomizing chamber I5. Preferably, the atomizing chamber is preheated by means of conduit I3 to prevent the particles from freezing against the walls of the atomizing chamber. The majority of the particles thus. formed find their way into the vertical combustion chamber 2| by means 'of the outlet duct I9. The majority by gravitational diierentiation and drop directly cinto the -vessel containing the molten lead by means of the open end portion 22. The finely comminuted lead particles are drawn ofi at 32 and collected. in known manner.

In the preferred embodiment the finely comminuted lead particles are ignited in ignition zone 3|. Suitable ignition means for the burning of such iinely divided lparticles is provided by the jets 23. Such ignition is created by the introduction of a mixture of airand gas, such gas comprising a natural gas or methane. Burning is initiated by means of air pipes 26 and gas pipes 24. As the finely divided lead particles are ignited they are carried upwardly into a second ignition zone 33 where further burning occurs. Suicient air to sustain the secondary burning of the particles is introduced between the dome 34 and collar 35, shown by direction arrows A. The lead oxide thus formed is .drawn off at 32 in a substantially iinely divided com-` minuted state. V

Alternatively, pure particles of lead of finely divided and uniform size may be formed by dropping the dome 34 to form a tight fit with collar 35 and closing jets 23, or introducing an inert gas such as nitrogen in', place of the air and/or methane gas. The finely divided particles of unreacted lead of size are then drawn oi at 32 as described place civ-forming nely divided particles of'di/eafcted lead cr-lead oxides, lead sub-oxides maybe formed by introducing an insumcient supply of air or oxygen.

Lead sulides may be formed by admitting hydrogen sulnde to the combustion zone 3| in place of air or oxygen. other lead compounds may be formed in like manner by substituting other'v suitable gaseous reagents into the combustion chamber.

Among the advantages realized by the present invention, it will be observed that by the gravitational return of the larger particles to the reservoir containing the molten metal the atomizing chamber is relieved of such rejected mateing out the above process and in the product.

and modications effected in the apparatus for of the heavier ccmminuted particles strike the wall 29 of the combustion chamber and drop Vpracticing the principle thereof without depart- 'i- Ving from the scope of the invention, it is inback into vessel |I containing the molten leadj. tended that all matter contained in the above In a preferred -embodiment (not shown) there 75. description or shown in the accompanying draw- Chlorides, carbonates and' shall be interpreted as illustrative and not a limiting sense. It is'also to be understood that the following claims are intended to cover all of the generic and specific features oi the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be slid t fall therebetween.

Having described my inventionl what I claim as new and desireto secure by Letters Patent is:

1. In a process for comminuting molten metal by beating and iiinging particles of said molten metal into a gaseous atmosphere, the improvement which comprises establishing a body of molten metal. coniining a portion of said molten metal in a restricted zone communicating with said body, beating said restricted portion to comminute it and iiinging the comminuted metal particles into a substantially vertically disposed iiue the lower end of which opens into said body o! molten metal at a region horizontally spaced freni said restricted zone, and establishing a regulated 'current of a gas in said iiue sufficient to carry away smaller metal particles but which permits larger particles to return to said body of molten metal by gravity.

2. In a process for comminuting molten metal by beating and ilinging particles of said molten metal into a gaseous atmosphere, the improvement which comprises establishing a body of molten metal, confining a portion of said molten metal in a restricted zone communicating with said body, beating said restricted portion to comminute it and tlinging the comminuted metal particles into a substantially vertically disposed flue the lower end of which opens into said body of molten metal at a region horizontally spaced from said restricted zone, and establishing a regulated current of a gas in said ue suiiicient to carry away smaller metal particles but which permits larger particles to return to said body of molten metal by gravity, iinally collecting the smaller particles in a substantially solidified comminuted state.

3.In a process for comminuting molten metal assaoos comminute it andfiiinging the comminuted metal particles into an inert gaseous atmosphere within a substantially vertically disposed flue the lower end of which opens into said body oi' molten metal at a region horizontally spaced from said restricted zone. and establishing a regulated current of said inert gas in said iiue sumcient to carry away smaller metal particles but which permits larger particles to return to said body of molten metal by gravity.

4. In aprocess for comminuting molten metal by beating and fiinging particles of said molten metal into a gaseous atmosphere, the improvement which comprises establishing "a body of -molten metal, conning a portion of said molten metal ina restricted zone communicating with said body; beating said restricted portion to comminute it and inging the comminuted metal particles into a substantially vertically disposed iiue the lower end oi' which opens into said body of molten metal at a region horizontally spaced from said restricted zone. chemically reacting the lsmaller particles with a gaseous reagent within said iiue, and establishing a regulated current of a gas in said flue suiiicient to carry away smaller chemically reacted metal particles but which -permits larger particles to return to said body of molten metal by gravity.

5. In a process for comminuting molten metal by beating and iiinging particles of said molten metal into a gaseous atmosphere, the improvement winch comprises establishing a body oi' Y molten metal, coniining a portion of said molten by beating and fiinging particles of said molten metal in a restricted zone communicating with said body, beating said restricted portion to comminute it and flinging the comminuted metal particles into a coniined zone within a iiue spaced from the point of comminution and having one end of said iiue opening into said `body of molten metal at a region horizontally spaced from said restricted zone, establishing a regulated current of gas in said ue sufiicient to carry away the smaller comminuted particles but which permits larger particles to return to said body of molten metal by gravity, chemically reacting said smaller particles within said nue, whereby the said comminuted larger particles are return to said body of molten metal in a partially molten and substantially unreacted condition.

SIEGFRIED HILLER.

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