US1241834A - Process of producing aluminum nitrid. - Google Patents

Description

H. L. DUNCAN.

PROCESS OF PRODUCING ALUMINUM NITRlD.

APPLICATlON F|LED OCT. 12. I9|6| Patented 00. 2,1917.

1 so as to impingemn the fa 124L834. I Continuation inypa rt or attenuation SerialNo 587,419, filed Qctober1'7; 1910. Thi I I I 12,1916. Serie1No.'125,158.

c To all whom it may c ohc ern:

' centralized,vluminousflame wit UNITED T T TENT mamnfinity M;

Be itknown that LHARRY'L. DUNCAN, a citizen of the United States, now residing at Mahwah, Bergen county," New Jersey, have madea certa n new and useful Invent1on- Relating-to Processes of Producing Aluminum Nitr icl "of which the following is a. specification, taken inconnection With the accompanying di awing, which forms 1 part I ofthe same. 'Th s applicatlon 1s a continuaz-;

tion in partthat is, contains subjeot natter taken in from .my "copending "application 587 419, filed'October 17, 1910.'

ally to'proo- This inyenti'on relates especl esses for producing niti ids of aluminum and other metals by supplying the hot carbonaceous falunii'nous charge at materiah for instance, to a rotatingtreating kiln through which it is, gradually fed and simultaneeusiy' agitated. The material maybe heated by a I min the kiln which may be produced bysupply-ing to the discharge 'en'd of'the kiln a lowfpressure diffuse heatingyj'et or, stream of luminous flame producer gas vand injecting :substantially axially intolthe kiln a high pressure jet of air or' other oxidizer engaging said heating -stream i'andi forming therewith a substantially centralized heating flame transmitting heat I to the kiln walls and" material, While kept from undesirable contact therewith'bythe layer of de a 'wa1l ga ses in engagement withithef kiln walls and Ina-x terial. A nitrogenous treat.

jet of hot into the kiln ig agitated t the: same tion' on the producer gas may; be injecte charge oi'"material an moon-y; without exertmguhdsflable kiln walls and forthis,purpose the jet ma be of high pressu're and discharged fnom flattened nozzle substantially inline withthe bank otmaterial. Af nitrogenous reducing atmosphere is preferably maintained in the lower lldl' 'Of the treating kiln at a slight excess of pressure ahoye' the" outside 311' to nnnimize ingressthereo-f and the combustible gases: discharged fro'm' the treating kiln may'l he used to heat: the charge of material as' 'bynburning them in a?- p'reheating k111i;

An illustrative "form of apparatusfor can. rying out thISPIQCBSS-iS ShOWQ 1n a-" so1ne"- What. d agrammatic way in the accompanye Specification of Letters Pate aiit;

*- ing drawing in Whihh l glure through thie treating ake with whicha the d ischarge' Y sired, provided en the e packingring's washers oniinembeis 5fiseeur'e ble elements of .these ykilnn:gasesi; ihay-.be-f

discharge throat 12 an 'tat'ed ihany desired wa chamber 14: and stack .c

withii nthe' portf,9"and;up1bl'1e the desired pressure a suitable fencer blower 23 "connectedicimithtr ingly-"Ipromoted." 3

section and Fig.

along the "line 22 of Fig, rotary kiln 1- may he p my, preferably inert, I

able materialtand .i' ."1th'nia c onstllfl charge throa 2; the kilnibeing meniited an rotated any desiredwwvayz cooperates, is preterahlywtightl I ycon nee therew th, a suitable han 4 ilngi'i-fl de coopei ating with suitable metallic Dr? to the sons to make a tight kiln join The upperencl'ot' the" kilma dicatedgbewithe bott' y ypepina similarly connectedf'tvith th whousing through the fi ange Wand packing g-Rva'sher or connections 8; The kiln"gases fromitlns". treating kiln 1 may be:.disoharged'itlinoug the port 9 after pa'ssing up thro'ughjth 1 y j i i passage 10 in the, hoilsing landrthe combiisti this kiln may cooperate-With 5 v'snitabie'stf fsuffieien I to maintain the desireditstaek ltaf t i the kiln and'draw inadditidhx throng the "ii'sualeki ln jointf-l'fic matromote -tl1 heating action in thi klln. The,

discharged from-this pre" ating' N erably slides-{past a j mounted on the supper :and %;p1(3 .l1t1ng leakage pfgas from the? assag l9 Siii. ablehir'injecting gp-ipespgQi w "the 6 2 this way the eloeity-of h "asesxpas.

ing thi oughy the portQegintovt pinkie-1 kilnrll;maybeincreased t the desin e. ea tentgand combiistion' the through, the regulatin arranged in the casing and operated at the desired speed by the pulley 27. The aluminous material is gradually feddown the preheating kiln by its rotation and becomes quite highly heated therein so as to be hot when discharged into the treating kiln 1. Additional carbonaceous material ma'j; be conveniently incorporated with the charge entering the treating kiln by feeding such pulverized carbon or the like from the hopper 28 and connected conveyer casing 29 by the feed screw 30 driven at the desired speed by the pulley 31. This carbonaceous material thus becomes mixed with the aluminous portion of the charge as the materials enter the treating kiln and becomes intimately mingled therein as they are continually ag tated and simultaneously fed down through the kiln in the form of an inclined bank of material on its ascending side. The material 60 entering the treating zone at the lower end of the kiln is thus substantially homogeneous and has been still more highly igeated in the upper part of the treating iln.

It is desirable to maintain within the suchproducer gas to the lower end of the treating kiln in sufiicient amounts, a slight excess of pressure may be maintained within the kiln above that of the outside air which tends to prevent air being drawn into the kiln through the various openings in the hood. A treating jet of such nitrogenous gas is also preferably injected into the discharge end of the kiln in such way as to impinge on the falling agitated charge of material and effect thedesired reactions therein, which of course develo considerable heat Where aluminum nitrid is formed. It is desirable to inject the treating gas in the form of a flat treating jet having its flat side substantially in line with the bank of material extending up through the kiln so as to impin e upon the material throughout a considerab e treating zone without exerting undesirable action on the kiln walls which may with good results be coated with a protective layer of the forming material. This fiattened treating jet 35,, may as indicated, be discharged at an angle of some thirtydegrees or so to the adjacent kiln walls or bank of material on which it impinges, and

this gas jet may be discharged from a suitable nozzle 36 in the hood connected with a pipe 37 leading, from the producer 39 and provided with a regulating valve 38 so that the hot treating ases may be supplied at the desired high ressure. This producer should, of cours be operated so as to secure a sufficiently high temperature in the treating jet to definitely effect the desired chemical reactions in the material in the kiln and for this purpose the producer may be blown with air without the use of steam or similar cooling means and the producer gas may of course be still more highly heated by well known regenerator or other heating devices before injecting it into the kiln. In order to preliminarily heat the treating kiln and maintain it and thematerial fed therethrough at the desired high temperature, a luminous heating flame may with advantage be employed, preferably in a sub stantially centralized position within the kiln so as to transmit'heat by radiation to the material and kiln walls without destructive action thereon, and thus supply at least a large part of the heat required to bring the charge up to the combining temperature, although if desired additional heat can of course be supplied as by electric heating elements arranged in the kiln walls for instance. A substantially centralized jet of air or other oxidizing material together, if desired, with suspended particles of oil, powdered coal or other fuel .for combustion therewith may be injected into the kiln by any suitable injecting devices so as to produce in this way a luminous heating flame which is kept substantially or largely out of contact with the kiln walls or material: because of the interposed reducing atmosphere in the kiln. If desired, a suitable high pressure air jet may be substantially axially injected into the kiln to burn in the reducing atmosphere therein and transmit heat to the kiln walls and material without undesirable contact therewith. For some purposes it is desirable to supply to the kiln in connection with such air jet a diffuse low pressure jet or stream of luminous flame producer or other gas. Such a low pressure heating stream of gas may be injected through the flaring gas port 46 connected with the pipe 47 from the producer-l9 and having the controlling valve 48 therein. This producer is preferably operated to give luminous flame gas which may be enriched by incorporating hydrocarbon oils or similar material therewith. A high pressure directive air jet may be injected into the kiln along the line 50 through the air nozzle 51 supplied with air from the fan or blower 43, the pressure or velocity of the issuing jet being regulated by the valve 52 so as to be in'the neighborhood of one to two ounces equivalent pressure on entering the kiln so as to give the resulting flame a sulliciently centralized position. The rough kiln walls tend to hold practically stationary the layer of gases in contact with them so that these dead wall gases tend to prevent undesirable contact between the heating flame, preferably of highly luminous character. and the kiln walls and material. Anothelair jet teena e connected to the fan or blower 43 and sup plied with air, at the desired pressure and in the proper amounts through the regulating valve 42. This heating jet is adapted to cooperate with the gas passing through the nozzle 36 which is provided with a relieved portion 40 at its upper'discharge end and under these conditions the gas pressure should be suificiently low so as to inject through this nozzle a diffuse gas jet and prevent such forcible impingement upon the material as occurs under normal working conditions.

The treatingu-kiln may be put in operation by admitting sufiicient producer gas thereto to substantially displace the air therein and then preferably supplying luminous flame producer gas to the kiln in sufficient amounts so as to produce luminous heating flame therein in connection with the air jet's, These jets may be ignited'in any desired way as by the electric igniter 56 which may be inserted through a suitable opening 54 so as to bring the sparking terminals 55'adjacent the air jet to cause ignition when high tension electricity is passed through the-wires 57. Asuitable bushing 58 of course normally closes the opening 54 around this igniter and the opening is kept closed during the normal operation of the kiln, preferably by a door having a transparent window or peep hole to allow observation of the kiln interior. The heating flame produced under these conditions may have the shape and location indicated as 45 and the layer of dead wall'gas 61 tends to prevent-contact between this flame and the kiln walls or material. WVhen the material has beensufliciently heated the nitrogenous reducing gases in the kiln react with the a luminous carbonaceous charge forming nitrid and this action may be promoted by injecting the treating jet 35 of nitrogenous producer gas into engagement with the agitated material. This promotes the formation of a highly heated treating zone in the lower end of the kiln sothat the conversion of the material passing therethrough is ef fected to the desired extent before this material is discharged through the chute 33 plying the hot carbonaceous aluminous charge of material to a rotating treatlng kiln, 1n agitating and feeding said charge through said kiln in the form of an inclined bank of material, in supplying through the discharge end of said kiln a low pressure diffuse heating stream of luminous flame producer gas, in injecting substantially axially into said kiln a high pressure jet of air engaging said heating stream and form-' ing therewith a luminous substantially centralized heating flame kept from undesirable contact with the material and kiln walls by the dead wall gases while transmitting heat thereto, in maintaflining in the lower end of said kiln a nitrogeneous reducing atmosphere at a-pressure above that of the outside air, in injecting through the discharge end of said kiln afiattened high pressure nitrogenous t'reatingjet of hot producer gas to impinge on the falling agitated charge of material and convert the same into nitrid without exerting undesirable action on the kiln walls and in burning the combustible gases discharged from said kiln to heat the charge of material supplied thereto.

2. The process of producing aluminum nitrid which consists in supplying the carbonaceous aluminous charge of material to a rotating treating kiln and thereby agitating and feeding said charge through said kiln, in supplying through the discharge end of said kiln a low pressure diffuse heating stream of luminous flame producer gas, in injecting substantially axially into said kiln a high pressure jet of air engaging said heating streamand forming therewith a luminous substantially centralized heating flame transmitting heat to the material and kiln walls, in maintaining in the lower end of said kiln a nitrogenous reducing at- ,charge end of said kiln a flattened high pressure nitrogenous treating jet of hot producer gas to impinge on the material and convert the same into nitrid without exerting destructive action on the kiln walls.

3. The process of producing metallic nitrid which consists in supplying the carbonaceous charge of material to a rotating treating kiln and thereby agitating and feeding said charge through said kiln, in supplying through the discharge end of said kiln a low pressure diffuse heating stream of producer gas, in injecting substantially axially into said kiln a jet of air engaging said heating stream and forming therewith a substantially centralized heating flame transmitting heat to the ma terial and kiln walls, in maintaining a nitrogenous reducing atmosphere in the lower end of said kiln and in injecting a high pressure treating jet of hot producer gas into said kiln to impinge on the material therein and convert the same into nitrid go without exerting destructive action on the kiln walls. a

4. The process of producing metallic nitrid which consists in supplying the carbonaceous charge of material to a treating kiln, in agitating and feeding said charge through said kiln in the form of a bank of material, in injecting into said kiln a flattened high pressure nitrogenous treating jet of combustible gas to impinge on the agitated bank of material and convert the same into nitrid without exerting destructive action on the kiln walls and in injecting into said kiln a jet of air engaging said treating gas and forming therewith a heating flame transmitting heat to said material and kiln walls without undesirable action thereon.

5. The process of producing metallic nitrid which consists in supplying the charge containing reducing material to a treating kiln, in agitating and feeding said charge through said kiln in the form of a bank of material, in injecting a narrow nitrogenous treating jet into impingement with the agitated charge of material to convert the same into nitrid without exerting undesirable destructive action on the kiln walls, in maintaining a nitrogenous reducing atmosphere in the lower part of said kiln and in heating said material.

6. The process of producing metallic nitrid which consists in supplying the charge containing reducing material to a treating kiln,

in agitating and feeding said charge through said kiln in the form of a bank of material, in injecting a hot small area nitrogenous treating jet into impingement with the agitated charge of material to convert the same and in maintaining a nitrogenous reducing atmosphere about said charge of material in the discharge end of said kiln.

7. The process of producing aluminum nitrid which consists in supplying the carbonaceous aluminous charge of material to a treating kiln, in agitating and feeding said charge through said kiln in the form of a bank of material, in injecting a narrow nitrogenous treating jet into impingement with the agitated charge of material to convert the same without exerting undesirable destructive action on the kiln walls, in maintaining a reducing atmosphere in contact with said converted material at the discharge end of said kiln and in injecting an oxidizing jet into said kiln to form a heating flame therein transmitting heat to the material and kiln walls without undesirable action thereon.

8 The process of producing aluminum nitrid which consists in agitating the charge of material in a treating kiln, in maintaining a nitrogenous reducing atmosphere in contact with said material at one end of said kiln, in injecting into said kiln an oxidizing jet to form a heating flame in said kiln transmitting heat to said material without destructive action thereon and in injecting a jet of nitrogenous treating gas into impingement with said charge of material to convert the same into aluminum nitrid.

9. The process of producing aluminum nitrid which consists in supplying the carbonaceous charge of material to a rotating treating kiln and thereby agitating and feeding said charge through said kiln, in supplying combustible nitrogenous treating gas to the discharge end of said kiln to maintain therein a nitrogenous reducing atmosphere at a pressure at least equal to that of the adjacent outside atmosphere, in injecting substantially axially into said kiln a jet of air engaging said gas and forming therewith a substantially centralized luminous heating flame transmitting heat to the man terial and kiln walls without undesirable contact therewith and in bringing said material while highly heated into engagement with said nitrogenous treating gas to convert the same intoraluminum nitrid.

10. The process of producing aluminum nitrid which consists in supplying the charge containing reducing material to a treating kiln, in agitating and feeding said charge through said kiln in the form of a bank of material, in injecting a narrow nitrogenous treating jet into impingementwith the agi tated charge of material to produce nitrid therein without exerting undesirable destructive action on the kiln walls, in main taining a nitrogenous reducing atmosphere in the lower part of said kiln and in heating said material.

11. The process of producing aluminum n1trid which consists in agitating and feed ing the charge of aluminous material through a rotating treating kiln, in maintaming a nitrogenous reducing atmosphere 1n contact with said material in the treating zone of the kiln, in supplying heat to the material 'from a substantially centralized luminous flame in the kiln,.in' injecting a high pressure jet of hot nitrogenous gas to impinge on the heated material in said treating zone at an angle of more than fif teen degrees to the adjacent kiln walls to convert the'material into aluminum nitrid and in preventing substantial ingress of oxidizing gases into the lower end of the kiln adjacent the kiln walls or material.

12. The process of producing aluminum nitrid which consists in agitating and feeding the charge of aluminous. material through a rotating treating kiln, in maintaining a nitrogenous reducing atmosphere in contact with said material in the treating zone of the kiln, in supplying heat to the material from a substantially centralized luminous flame in the kiln and in'injecting hot nitrogenous gas to impinge on the heat ed material in said treating zone at an angle of more than fifteen degrees to the aoljacent kiln Walls to convert the material into alu-' minum nitrid.

13. The process of producing aluminum nitrid which consists in agitating and feed ing the charge of aluminous material through a rotating treating kiln, in maintaining a nitrogenous reducing atmosphere in contact With said material in the treating zone of the kiln, in supplying heat to the material and in injecting hot nitrogenous gas to impingeon the heated material in said treating zone at an angle of more than fifteen degrees to the adjacent kiln Walls to convert the material into aluminum nitricl.

14. The process of producing aluminum, nitrid which consists in agitating and feeding a charge of aluminous material through a rotating treating kiln, in producing luminous heating flame in said kiln to radiate heat to the kihi walls and material, Without undesirable contact therewith, in maintaining a nitrogenous reducing atmosphere in contact with the heated material in the treating'zone of the kiln and in injecting a jet of hot nitrogenous gas into said kiln to impinge on the heated material in the treating zone at an angle of at least as much as twenty degrees to the adjacent kiln Walls to convert the material into aluminum nitrid;

15. The process of producing aluminum nitricl which consists in maintaining a nitrogenous reducing atmosphere in contact with the alnminous material in the treating zone, in supplying heat to the material and in injecting-a high pressure jet of hot nitrogenous gas to impinge on the heated material in said treating zone at an angle of more than twenty degrees to convert the material into a1 uminurn nitrid.

16. The process of producing aluminum nitrid which consists in maintaining a nitrogenous reducing atmosphere in contact with the aluminous material in the treating zone, in supplying heat to the material and in injecting nitrogenous gas to impinge on the heated material in said treating zone to convert the material into aluminum nitritl. I

HARRY L. DUNCAN. Witnesses:

J'Essn B. KAY, Cnannns EBERHART.

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