US1352193A - Proces for fixing atmospheric nitrogen - Google Patents

Description

C. P. HIDDEN.

PROCESS FOR FIXING ATMOSPHERIC NITROGEN. APPLICATION man 1uLY5,1919.

Patented Sept. 7,1920.

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entrant CHARLES P. HIDDEN', OF PROVIDENCE, RHODE ISLAND, ASSflGIQ'OItV T0 ITROGEN PROD- TICTS COMPANY, A CORPORATION OF RHODE ISLAN D.

PROCESS FOR FIXING ATMOSPHERIC NITROGEN.

maaien.

Application led July 5,

To all whom. t may concern:

Be it known that I, CHARLES P. HrDDnN, a citizen of the United States, residing at Providence, in the county of Providence and State of Rhode Island, have invented certain new andA useful Improvements in Processes for Fixing Atmospheric Nitrogen, of which the following is a specification. y This invention relates to a process for fix ing atmospheric nitrogen and` in its preferred form said process may be regarded as an improvement upon that described in the patent to John E. Bucher, Number 1,120,682, dated'December 15, 1914; but whereas said known process is preferably a continuous one, that described herein is preferably of the batch type.

The principal aim of the present invention is to reduce the cost of fixing nitrogen in the form of a cyanogen compound, to wit, alkali metal cyanid.

Another object of my inviention is to eliminate, in very large measure, the tend v ency of the charge under treatment, to adhere to the walls of its retort; especially where cooling occurs within said charge after cyanid has Vbeen formed therein, where by the charge for a time becomes very tacky and adhesive.

Another object of my invention is to' greatly reduce the tendency for cyanid formed during the course of the Bucher process, to volatilize; such vaporized product usually being lost, as it cools, owing to its conversion to sodium carbonate .or the like in the presence of the atmosphere of mixedI carbon .,monoxid and nitrogen.

These and other objects ofmy invention will be hereinafter referred to and the novel combinations of steps which constitute my process will be morel particularly pointed out in the claims appended hereto. In the accompanying drawing whichv forms part hereof, I have exemplified a preferred furnace construction, in combination with certain auxiliary. pieces of apparatus, which together with said furnace constitute a system especially well adapted to the effectuation of said process.

As, however, I am aware of various changes and modifications which may be made both in said process and ap aratus, without departing' from the spirit or my invention, l desire to be limited only by the Specification of Letters Patent.

ter and the outer air.

Patenten sept. a, aseo.

1919. Serial No. $08,772.

scope of said claims, broadly interpreted in the light of my disclosure.

Referring to the drawings:

Figure l is a somewhat diagrammatic, vertical section of a cyanizing furnace.

Fig. 2 is a fragmentary detail section, taken on theline II-II of Fig. 1. v

Fig. 8 is a similar section taken on the line III- IH of F ig. 1.

Fig. 4-is the diagram showing the preferred arrangement of the dierent piecesof apparatus and connections therebetween.

Considering rst the furnace and its more immediately associated parts: The brickwork 1 of said furnace is preferably disposed to form a chamber, the annular wall of which has been designated 2. -Within this chamber is a hopper 3, the lower end v The charge to be treated, preferably in briqueted form, is introduced into the hopper 3 from an auxiliary or feed hopper'9,

through a rotatable feed valve 10. 'This latter' is ofV known construction and is provided with a pocket which receives a small portion of the charge and rotarilyl delivers it to hopper 3, while at the same time cutting ofi' communication between the lat- 'Ihe air in the interstices of the so admitted charge may be eliminated by sweeping it out with nitrogen passed in through the pipe,10. A valve of this type is shown in the United States patent to .William D.l Mount, No. 1,304,697, dated-May 27, 1919.

The bell 4 is normally overbalanced by a4 weight 11 upon an arm 12, secured to an end of the shaft 7- The hopper 3 and its cover 8 may be supported by a frame 13; and the lower end of said hopper preferably abuts against a casting 14, which provides a seat for the bell 4.

Spaced a short distance below the casting 14, is the upper edge of the retort 15. In

Aorder that the charge, after treatment, may freely discharge from this retort, l prefer which 1n turn may be carried by the brick-y work.,

preferably To protect the retort from the hot gases to which it is exposed, and which, if said retort be of iron, tend to soften it and thereby allow it to become deformed, I prefer to substantially surround such exposed portions by brickwork 17.

To permit retort 15 to be readily withdrawn from the furnace, its lower edge .15"

is flanged or enlarged to sustain a packing 18, of kieselguhr, which surrounds the central portion of said retort. AI prefer to similarly pack kieselguhr around the hopper 3, as at 19, in order to prevent ingress of air to the space below the bell 4, as well as to provide heat insulation.

Below the hopper 3, spaced some inches therefrom, is a trap,-

made in two pieces, 20--20. When the retort 15 is loaded, the bri uets and preferably in its lower end flow out `laterally and orm a slope as at 21. To prevent such briquets from moving out too far, I provide a semicircular flange 20 aroundthe edge of each trap section.

There is usually considerable space between the casting 14 and the upperv surface of the charge; of illustration, I have indicated by a dotted line designated 22. A Each trap section may be strengthened by radial ribs 20, and said sections are separated from each other by a narrow space 23, to permit of their free and independent movement.

The trap sections are pivoted upon shafts 24; two shafts being provided for this purpose, one upon either side of the chamber 25 through which' the charge falls when said sections are moved to their open positions.`

Shafts 24 are journaled in brackets 26, each preferably provided with a double wall, to afford a space 26 aroundl each shaft journal, whereby thev journal may be cooled by a stream of the passage of,` for example, relatively col'drnitrogen gas. This cooling current of nitrogen may be introduced into the journal vbracket via pipe is connected pipe 27 which leads the gas into space 26'; said gas emerging at the opposite end of the bearingthrough pipe 28.

lAs the system for coolingI the journals may be the same in each case, have exemplified but one set of connections for this purpose.- I alsoprefer to make each shaft 24 hollow, so that gas may be passed r therethrough from pipe 27, and to provide each end of -said shaft with a stuffing box 24', to afford .gas-tight connections with the pipes which respectively introduce the cooling gas and conduct the 4same away from said shaft. The semicircular traps may be keyed fast to their respective shafts, as at 29, and are of heat resistant alloy, larly adapted to withstand the heat to which they are subjected.

Vwhich surface,`for purposes 27, to which Amounted upon a shaft 48.

or are otherwise simibe lowered somewhat slowly and to better disrupt the charge.

I prefer to bulge up the center of the trap, considered as a whole, as at 33, to aid in distributing the gases. In the construction shown by) way of illustration, the line of severance etween the two substantially semicircular trap sections cuts diametrally across this protuberance.

The hub 34 of each trap section may'conveniently be made equal in length to the radius of said section and be -connected thereto by a web 34. To afford clearance for the trap sections, when ythe latter are being lowered, the brickwork may be cut away as at 35.

Chamber 25 is covered by a brickwork dome 36, save where thev lower extremity of the retort 15 closes the orifice in 'said' dome. At spaced intervals around this dome section 20 v be lowered, and then the other, or

are-ports 37 in communication with a conduit 38' which extends around the retort, and which either receives gas from a conduit 39, or delivers gas to Va conduit '39.

The sp which similarly lead into a commonconduit 41, whence gas passes through va conduit 42, or enters through conduit 42',

, Chamber 25 is provided near the bottom thereof with a breaker 43, and the top of this should be vsufficiently below. the axes of the n'shafts 24, to permit the trap sections to. move into their vertical positions.V The preferably star-shaped breaker is massive t0 resist rupture `when the falling charge ace above the retort 15 Iis in com` Amunication with a plurality of ports 40 strikes the center thereof, and its respective arms are edged, as at 43', to aid in breaking up the charge.

In the walls of chamber 25 are twyers 44 through which jets of cold nitro en may be directed into the chamber 25. hel bottom of this chamber is preferably sloped inwardly and downwardly, as at 45, and the central orifice 46, therebelow is normally covered by a seal-protecting fiy-gate 47,

the orifice 46 may be provided with a flange 49', which may conveniently be formed integral with the casting 49.v

A grooved pan 50, carried by a lever 51, normally seals theY opening 46 substantially gas tight, through the intermediacy of The lower edge of kieselguhr 52, or the like, .with which the '53, at each end of which is a fianged roller 54, which rides upon a rail 55. These rails are provided with stops'55, which limit inward travel of the shaft 54, whereby to center pan 50 with respect to orifice 46. The pan 50 is overbalanced by a weight 56, which may be integral with lever 51. Veight 56 normally reposes uponfa plate 57.

I prefer to operate the so constituted valve by the following simple mechanism. Weight 56 is provided with an upturned hook56.J which is adapted 'to interlock with a hook 58 upon the end of a rod 58. Mounted for reciprocal motion upon plate 57, is a hollow wedge block 59, and weight 56 may be cut away. as at 56, to permit of the insertion of Wedge 59 therebeneath. The outer end of said wedge is provided with a boss 59', for the reception ofl a pipe 60 which is firmly secured to the wedge. Rod 58 is axially movable in said pipe. l prefer1 to provide a stufiing box 61 around the pipe 60 and a corresponding box 61 upon the outer end of said pipe and around the rod 58.

Below the pan 50 is a chamber 62, the lower end of which is closed by a hopper 63, within which are mounted breakers 64. These may be of any known and suitable construction and need not be herein further described, other than that' I may state their shafts 65, are preferably gear-ed together, as by gears 66; one of these shafts being driven, as by a worm wheel 67. Below the breakers 64, is a staunch screw conveyerA 68-68.

l prefer to Cool the hopper 63 'externally as well as internally. To this end, air or ntrogen may be passed through the pipe (i) into the space 70 which surrounds said h )pper, and thence out via pipe 71. Relatively coolnitrogen is introduced into said hopper through the shell 68 of the conveyer, and this cools the charge in the latter, and also that portion of thecharge which reposes in the hopper 63. By the time that said nitrogen has passed up through chamber 62 for emergence through the conduit 72, for storage in the receptacle 72', it is usually quite hot, even before it passes into the preheater 73, shown in Fig.y I

Referring now more particularly to Fig. 4, it will be noted that said preheater is adapted to heat not alone the nitrogen deliveredthereto from the tank 72', but also carbon monoxid delivered to said preheater through conduit 74. A part at least' of this carbon monoxid may be formed in the car bon monoxid producer 75, which receives a gas, preferably consisting in large part of carbon dioxid, from the outer passage 76 of 'the heat interchanger; said gas passing into the producer 75 via pipe 77.

y It may be explained at this pointthat the CO2 laden gas thus suppliedto the producer,

was delivered to passage 76 through a pipe 78 which received said gas from a pump 79; a pipe 80 delivering said gas to this pump from a receptacle 81, in which said carbon dioxid is produced.

The receptacle 81 is preferably provided with an agitating device 82, driven by a Worm and wheel 83; the shaft 84 of said device, being journaled as at 85-86, and` having stuihng boxes 87, to prevent ingress" of air to receptacle 81. f

The second passage 88, in the heat interchanger, conveys carbon monoxid from the cyanizing furnace to the receptacle 81; conduit 88 being most conveniently connected to that designated 42.

The preheater is connected to the furnace to enable the discharge of either hot nitrogen or hot carbon monoxid into the retort, as desired; valves 89, 90, 91, 92, 93 and 94 being provided for this purpose. In the preferred apparatus, the connection 95 with its valve 96, affords means to introduce oxyf1 gen into the producer 75.

The mode of operating the apparatus and the process which may be effectuated therein will now be more particularly considered.

After the charge has been measured into hopper 3 by valve 10, the bell 4 is lowered to drop said charge into retort 15; the trap sections 2O at such time being in their closed positions. An annular space is afforded at 21 through which gas may freely enter said charge at the bottom of the retort, from all sides thereof.

Valves 90, 92 and 94 will be closed at this time, while valves 89, 91 and 93 willbe cpen. The pump 79 is started, and the agitator 82 is caused to rotate slowly withinl the receptacle 81. This receptacle contains a mass of powdered iron, nickel, or the like, which is adapted to actas a catalyst for the conversion of carbon monoxid into' carbon dioxid at a suitable temperature, to wit, 4003-600O C. At 400J C., finely divided nickel, especially, is capable of converting carbon monoxid nearly quantitatively intocarbon dioxid, with attendant deposition of pure carbon, in very finely divided form, upon the catalytic mass. When the pump 79 is thus started into operation, the space in and about the retort is at first filled with a mixture of' nitrogen and carbon monoxid,-the nitrogen as a result of the previous operationy of the furnace,-and this mixture leaves the furnace via conduit 42 and passes thence through conduit 88 to receptacle 81. lf the furnace has just previously been in operation, this gaseous mixture will, by the time it reaches receptacle l8l, be at a temperature which favcrs the llt passage 76 to pipe 77. This gas will receive heat from that passing through conduit 88; so that by the time it enters the producer 75, it will be quite hot.- Within the producer .75 is a mass of incandescent coke and as the hot CO2 enters this producer, oxygen is also fed in through pipe v95 to react with the coke exothermically, in a known manner, the carbon dioxid, oxygen and carbon being converted into carbon monoxid; with the result that hot gas having a very high content of OO, passes from the producer through pipe 74 to the preheater 73 in which its temperature is preferably raised ,to 1,0000 C., or higher. Normally the preheater needs to supply but little heat to this gas on account of its temperature when leaving the producer.

The gas now passes through conduit 39 to the distributing conduit 38 whence itlows through ports 37 into the space just below the dome 36. As the pan 50 is in its closed position atf-su'ch time, said gas can not flow downwardly but is forced to enter the charge, at the bottom of the retort. The stream of highly heated gas then passes through substantially all partsV of the charge and Hows out at the top and thence through ports 40 to conduits 41 and 42. After a few preliminary cycles of the gaseous stream, the gas entering conduit -88of the heat interchanger will be at a temperature approximating 800 to 900 C., and its temperature will thereafter rise as the temperature in the upper part of theI retort 15 approaches 1,000o C., or slightly higher.

As the gas becomes more nearly pure CO, its conversion in receptacle. 81 into C()2 becomes more nearly quantitative, with the result that a copious deposition of carbon is effected in-this receptacle. This carbon, to-

consumption of oxygen and fuel in the producer 75; while it also reduces the burden upon the preheater 73. v

It will be understood that for economy of operation, the possibility of loss of heat by radiation from vaiig/us parts of the system, is reduced to a minimum by heat insulation.- A

The great advantage in thus heating the whole charge by means of a stream of substantially non-cyanizing gas, rather than by externally liring' the retort, is that the heating operation can be conducted in very much4 less time,

and the charge is more uniformly heated throughout. This problemV of supplying heat to the interior of the charge in question is one which has agitated the minds of those concerned with this art, for a number of years. Various methods of heating lhave been proposed; but it has been found in practice that hours of heating were required to cause the heat to penetrate from the walls of the retort radially to a depth of even six inches into the charge. This is due to the fact that when the charge is cold, or relatively so, it is an exceedingly bad conductor of heat. As its temperature is raised,

lit at first very gradually changes its heat conductivity, until as the reaction temperature is approached, it more rapidly becomes heat conductive.

In the rocess described in said patent to John E. ucher, the gaseous current of nitrogen, of course, becomes heated during its ascent through the charge, and hence, to some measure, tends to disseminate heat.

The great difliculty here was, however, that as any part of the charge approached reaction temperature, reacted to form cyanid, and this notwithstanding that the entire charge was not uniformlyv heated. When cyanid has thus formed, it thereafter slowly volatilizes, and the stronger the current of nitrogen,-espe cially if such current be hot,-the greater the volatilization of said cyanid.

', This vaporized cyanid was then carried up by the nitrogen stream and as the top of the retort was approached, the content of carbon monoxid 1n thisv gaseous current became increasingly larger. ture of about 850O C., a comparatively few er cent. of carbon monoxid in the latmosphere surrounding the cyanized mass, especially if the cyanid be in vaporous condition, reeonverts the cyanid to sodium carbonate. This causes a deposition of sodium carbonate in the upper relatively cool end of the retort, and this increased content of carbonate aids in choking the retort, to prevent a downward movement of the charge in a continuous furnace.

The result of this volatilization of cyanid which-is, so to speak, prematurely formed in the retort, is that not only does it hinder the feed through 4the retort, but the yield of product is very7 materially reduced.

In the preferred form of the present pro- At a tempera-- the nitrogen at once l cess, owing to the high content of carbon monoxid in the gas supplied to the charge during the heating period, there is practically no chance for cyanid to form, while sodium carbonate does not volatilize or decompose appreciably underthe conditions and at the temperature to which the charge is heated. Hence, there is no excessive production of. sodium carbonate in the upper end of the retort; but rather the distribution of said carbonate is maintained sub stantially uniform throughout the charge.

Assume now that the charge has been subjected to heat treatment in the furnace, until its temperature isvapproximately 1,040O C. Valve 96 is now closed and the pump is stopped. Valves 89, 91 and 93 are also closed, and valves 90, 92 and 94 are opened. Nitrogen preheated, preferably, to about 1,050o C. then Hows through the conduits 42-4l and ports 40, into the space below the gas-defiecting arch 36; whence it passes down through the charge, in substantially the same manner as the currents of carbon monoxid had passed up, and thence out by ways of ports 37 and conduits 38-39. The plate 14 and bell 4 are preferably formed of a heat resistant alloy adapted to withstand the temperature of the incoming nitrogen.

The current of highly heated nitrogen thus passed through substantially all parts of the already highly heated charge, causes an exceedingly rapid conversion of sodium carbonate, in said charge, into sodium cyanid, in accordance with the reaction;

Nazcomcaruzzeuacuaraoo.

In this connection, considerable advantage is gained' by thus causing the nitrogen current to iiow oppositely to the course of the CO current through the charge; since if the CO stream enters at the bottom, the top of the charge will be less highl heated than the bottom, after, say, one-hal hour of heat treatment.

The hot nitrogen stream then tends to reverse this inequality, thereafter. Also, since CO is evolved during the formation of the cyanid, and since the nitrogen stream is preferably pure,-there will, under the preferred conditions, be little C0 present in the gas in the top of the retort, although some 8 or 10 per cent. of CO may be present in the emerging nitrogen. The initially more highly heated, lower end of the charge will, however, favor cyanid formation in spite of this CO content, while the cooler upper end is constantly being more highly heated by the hot .nitrogen and the latter is, further, nearly pure, so that cyanid can copiously form in it, even at 850'950 C.

Moreover, an important characteristic of the present process, especially when the hot gaseous currents are reversed as aforesaid, or in any equivalent fashion, is that owing to the rapid formation of cyanid substan-.

tially'simultaneously throughout the'charge,

there is but little loss of cyanid by volatilization.

Normally,' after but comparatively few minutes of treatment with the hot nitrogen current, the latter may be shut olil by closing valves 90, 92 and 94. Plpe 60 is pushed in, to lock the hooks 56"-58, and rod 58 is then the worms 3l, are rotated to cause the sections 20 to descend. The still quite highly heated charge within the retort l5, is thereby dumped or poured, so to speak, and clears said retort and its trap sections before it has an opportunity to set.

This setting of the cyanized charge has caused great trouble in continuous furnaces; but the present procedure of dropping the charge out of its container, while its temperature is still above that at which the mixture of cyanid and carbonate, yor 'the like, in said charge tends to set and hence to become tacky, quite completely eliminates this difficulty; and this feature'ishence of great value substantially irregardless of the previous step or steps employed in effecting cyanization of the charge.

In the preferred form of the process, the descending charge,the tempearture of which had beenI allowed to fall to around 800, even before the trap was opened,is somewhat superficially chilled by the cold nitrogen blasts and impinges against the breaker 43, the vanes of which smash said charge, or already broken portions thereof, into fragments.

As soon as the charge fragments have fallen into the cooling Achamber 62, the pan 50 is moved to its closed position by pressing in upon 'both rod 58 and pipe 60, until the rollers 54 come to rest against the stops 55. Pressure upon rod 58 is then maintained while the pipe 60 is retracted. A s the wedge 59 is withdrawn from beneath weight 56, the latter drops and frees hook 56, while at the same time the seal 52 in the groove of the pan is -pushed up around the Hange 49. The fly-gate is preferably closed before the pan is rolled into position to close the same, to protect the' pan from any loose charge material.

The relatively cold nitrogen entering through the conveyer chills the fragments of charge in the hopper 63, while at the same time the breakers 64 break these fragments into pieces adapted to be handled by the conveyer. rlhe warm nitrogen emerging from chamber 62 may be storedl in the gasometer 72. f

After pan 50 has been moved to its closed position, trap sections 20 are turned up and the charge which has meanwhile accumulated in hopper 3 is allowed to descend into the retort, by lowering the bell 4 as before.

During the period when nitrogen is being supplied to the charge as above described, the nitrogen in receptacle 72', au mented by the nitrogen ascending from tide ably cooling pit 62, at such time, may be passedinto the preheater, via pipe 72".

It will thus be observed that while the furnace. is what may properly be termed a batch furnace, its operation may be made almost continuous, and as fast as one batch has been-preheated by hot CO andv thereafter treated with hot nitrogen to cyanize it, it is dumped into the cooling pit, and after the trap .has been closed and valve 50 'is moved to its closed position, the retort s ready for a new charge which meanwhile has been accumulated in hopper 3.

The cooling fragments of cyanized material are slowly removed from hopper 63 by the conveyer 68-68 and may then be more completely cooled in any suitable manner, with exclusion of air, until their temperai ture is4 sufficiently low to prevent oxidation ofthe cyanid to cyanate upon exposure of the briquets to the atmosphere.

I may here state that the charge to be cyanized in the manner described, is prefercomposed vof a briqueted mixture of the finely divided carbon obtained from receptacle 81 (although coke or the like may also be used), finely divided iron and sodium carbonate; this mixture being prepared and briqueted substantially in accordance with the disclosure of said John E. Bucher in .his patent aforesaid. I do not de- 'sire to be limited to this mixture, however,

as I am aware of a considerable number of mixtures which are well adapted for use in connection with my process, and the term alkalinoiis metal, used in' certain of the claims, contemplates both the alkali and alkaline earth metals.

I also do not desire to be limited to the treatment of the charge with substantially pure CO, or with nitrogen having a high CO content as a means for, in effect, idly vheating the charge; as I am aware that or the like, may

other gases, such as argon be used for this purpose. I do regard it, however, as highly desirable thatduring the heat supplying stage of the process, in which `ever,'advantages in so doing, even aside from, the. production of pure carbon yfor the process, in that, for example, the pump orv the like used to circulate the gas, may be operated at a relatively low tempera-ture,

and this without waste of heat energy;

while heat energy for the process is obtained in large part by the exothermic combination of oxygen and carbon in the producer 7 5.

' As the' described system produces more C() than is required in the process, thismore than compensates for mechanical losses and nitrogen additions. Excess of gas may be tapped off, preferably in the form of C02,

by opening valve 78.

I am aware that relatively sinall bodies ofy cyanizable charge may be heated by externally firing the retort. Also that larger bodies may be heated internally, as, for example, by using the charge itself as a resistor, as disclosed by said Bucher in his 'Patent No. 1,174,667, dated March 7, 1916;

etc. In no case, however, has it been known to heat the charge to, or substantially to, reaction temperature, and then suddenly change the atmosphere around said charge to vigorously promote said reaction in all parts thereof, substantially simultaneously. It is for this reeason'that I do not wish to be limited to heating by gaseous convection, direct or otherwise, although I greatly prefer to thus heat the .charge internally by direct gaseous convection. y

Finally, it will be observed that while the retort is preferably of iron, it is substantially unaffected by the gases conveying h eat thereto, since no gas capable"of oxidizing said iron is in contact therewith. This destruction of iron and of other comparatiyely inexpensive (and even some very expensive) retorts, has proven a hitherto insuperable difficulty, where such f retorts have been heated by the combustion products of producer gas', oil, or the like, on account .of the high C()2 content inf the gas impin ing against the retort. Heating by hot or its equivalent, entirely overcomes this diiiiculty; while, of coursel, it is not subJect to the diiculties attendant upon electrical heating. Moreoveig adequate electric current is not at all times available. I hence regard the heating of the charge to be cyanized, by highly preheated carbon monoxid as the most generally advantageous solution of this problem, while the conveyance of heat thereby, as is to be preferred, directly into the charge, permits ofconducting the operation in a retort having a capacity practically prohibited to one which is externally fired.

Having thus described my invention, what I. claim is: Y n

1. In the art of'ixing nitrogen by cyanizing a porous `charge,cconstituents of which l are capable of combining with free nitrogen to form a cyanid 'and carbon monoXid,-the improvement which consists in first internally heating said charge, treated as a batch,

substantially to cyanid-forming temperature, by direct gaseous convection, the gasiris employed to carry heat into the pores of said charge being incapable of supporting the cyanid-forming. reaction, then passing into said charge substantially pure nitrogen preheated to a temperature at which said reaction will occur, and again changing the atmosphere in the pores of said charge by passing relatively cool nitrogen therethrough, to sweep out -the carbon monoxid formed by said reaction while lowering the temperature of the batch being treated, below that at which carbon monoxid can deleteriously react upon the cyanid present in said batch. i 'I 2. In thecart'of fixing nitrogen by reactin with free nitrogen upona mixturecomprising analkalinous metal compound and carbon,-the improvement which consists in first heating an intersticed mass of said mixture to a temperature at which said mixture can react with pure free nitrogen to copiously form a cyanogen compound the base of which is said alkalinous metal, by passing a heat supplying gas, which is itself incapable of causing said reaction, through the interstices inV the mixture, then, while said charge is highly heated, changing the nature of the atmosphere in said intersticesto rapidly form said cyanogen Compound substantially throughout said mass, dumping said mam from the container in which said cyanogen compound was formed, before the liquid constituents of said mass can congeal, and thereafter cooling said mass to congeal said liquid constituents. 'A 3. In the art of fixing nitrogen by reacting in a receptacle with free nitrogen upon a. porous charge constituents of which. are capable of combining with said free nitrogen to form a cyanogen compoundwhich is Huid at the temperature of said reaction and which compound renders said charge adhesive while the fluid content of said charge is solidifying at a temperature below that at which said compound forms,-the.iinprove ment which consists in unloading said charge', as fa Ibatch, from said receptacle while the charge is still at a temperature above that at which it becomes adhesive, and cooling said charge in an innocuous atinosphere while breaking it into fragments.

4, In the art of fixing nitrogen by reacting in a receptacle with `free nitrogen upon a porous charge constituents of which Vare y capable of combining with said free nitrogen to form a cyanogen compound which is Huid at the temperature of said reaction and which compound renders said charge adhesive while the iuid content oi' said charge is solidifying at a temperature below that at which said compound ormsV-the improvement which consists in unloading said charge, as a batch, from said receptacle while the charge is still at a temperature above that` at which it becomes adhesive.

5. In the art iof fixing nitrogen 'by reacting in a receptacle with free nitrogen upon a porous charge comprising cabon and an alkalinousmetal oxygen compound, to form a cyanogen compound of said metal,-the improvement which consists in first supply,- ing heat to said charge while omitting to cyanize the same, by control of the atmosphere i`n the pores of said charge, until said charge is heated substantially to a temperature at which, if saidv atmosphere were pure nitrogen, said cyanogen compound would form, then changing the atmosphere in A'said pores, throughout the bulk of said charge, to provide an atmosphere capable of supporting 'the reaction yielding said cyanogen compound, whereby tocopiously form said` cyanogen compound, throughoutfsaid chargel substantially as a whole.

.6. n the art of fixing nitrogen by react-l' ing in a receptacle with free nitrogen upon` a porous charge 'comprising carbon and ani alkalinous metal oxygen compound, to form a cyanogen compound of said metaL-the improvement which consists inrst supplying heat to said charge while omitting to cyanize the saine, by control of the atmosphere of the -pores in the said charge, until said charge is heated substantially to a temperature at which, if said atmosphere were pure nitrogen, said cyanogen compound would form, then changing the atmosphere in said pores throughout .the bulk of said charge,- to provide an 'atmosphere capableof supporting a reaction yielding said cyanogen compound, whereby to copiously form said cyanogen compound throughout said A charge substantially as a whole, unloading by passing through the interstices in the mixture a heat supplying gas which is itself incapable of causing said reaction, then. while said charge is highly heated, changing the nature of the atmosphere in said interstices substantially simultaneously throughout said mass,- by replacing said gas by one favoring said reaction and supplying the nitrogen to be fixed thereby, whereby to coincidentally form said cyanogen compound in substantially all parts of said massi 8. ln the art of fixing-nitrogen by cyanizing a porous charge constituents of which are capable of reacting with free nitrogen to form a cyanid,-the improvement which 130 successively passing two streams of at Which said cyanid can copiously form, i successively passing consists in heating the said charge throughout by direct .gaseous convection to a temperature at which said cyanid can copiously form, by successively passing oppositely fiowingstreams of heat-carrying gas throug tli'e pores of said charge'.

9. In the art of fixing nitrogen by cyanizing a porous charge constituents of which are capable of reacting with free nitrogen to form a cyanid through the intermediacy of a catalyst in said charge,--the improvement which consists in heating the said charge throughout by direct gaseous convection toa temperature at which said cyanid cancopiouslyform, but below that at which said catalyst can sinter. v

10. v In the art of fixing nitrogen by cyanizing al porous charge constituents of which are capable of reacting with free nitrogen to form a cyanid,-the improvement whichI consists in heating said charge throughout by direct gaseous convection to a temperature at which said cyanidy can copiously form, by

heatcarrying gas through the pores of said charge, the first of said streams being incapable of supporting the cyanid-forming reaction' andthe second of said streams supplying nitrogen for said reaction and pro-l meting' the same.

11. In the art of fixing nitrogen b'y cyaniz-- ing a porous charge constituents of which are capable of reacting with free nitrogen to form a cyanidf-the improvement which consists in heating said charge throughout by direct gaseous convection to a temperatuge y two streams of heatcarrying gas through the poresl of said charge, the first of said streams having a high contentof carbon monoxid and being incapable of supporting the cyanid-forming reaction, and the second of said streams supplying nitrogen i motingthe same-i 12. In the art of fixing nitrogen by cyaniz.

ing a porous charge constituents of which are capable of reacting with free nitrogen to form a cyanid,-the improvement which consists in heatingsaid charge'jhroughout 'by direct gaseous convection to a temperature at which said cyanid can'copiouslyform, by successively passing two oppositely flowing streams of heat-carrying gas through said charge, the first of said streams being incapable of supporting the cyanid-forming reaction andthe second. of said streams supplying nitrogen for said reaction and .pro-

meting the same.

13. In the art of fixing nitrogen by cyanizing a charge comprising carbon and an alkali metal oxygen compound, which charge is capable of reacting with free nitrogen at a' temperature approximating 1,0009 C., to form a cyanid of saidalkali metal,-the imfor said reaction and proing a charge comprising carbon and an alkali high temperature,

Leganes,

provement which consists in heating the charge initially1 with gas rich. in carbon monoxid and at a temperature approximately that aforesaid, subsequently cooling said carbon monoxid to a temperature favoring the conversion of a considerable part of said carbon monoxid into carbon dioxid, catalytvmetal oxygen compound, which charge 1s capable of reacting with free nitrogen, at an elevated temperature, to form a cyanid o said alkali metal-, the improvement which consists in first heating the charge internally by a current of hot as which is incapable of promoting the cyanid-forming reactlon, and then cyanizing said charge by replacing-said current of hot gas by a current of-hot nitrogen. l

15. In the art of fixing nitrogen by cyanizing a charge comprising carbon and an alkali f metal oxygen compound, which charge is capable of reacting with free nitrogenat an elevated temperature, to form a cyanid of said alkali meta1,the improvement which consists in first heating the charge internally by acirculating current of hot gas which is incapable of promoting the cyanid-forming reaction, and then cyanizing said charge by replacing said current of hot gas by a current of hot nitrogen. I

16. In the art of fixing nitrogen by cyanizmetal oxygen compound, which charge is caable Aof reacting with free nitrogen, at an elevated temperature, to form a cyanid 'of said alkali metal,-the improvement which. consists in firstl heating the charge internally by a circulating heating current of gas having normally a high carbon monoxid content, 4while substantially simultaneously catalytically obtaining carbon dioxid and carbon for the process`during a temperature reduction in said current subsequent to the emergence of said. gas'from the charge being heated, said current being thereafter reheated to a to said charge, `in part at least by reacting upon carbon with oxygem. in the presence of the k carbon dioxid laden current, and cyanizing the so heated charge by substitutinv therewithin a currentof hot nitrogen for said hot current.

preparatory to its return the process during a temperature reduction- -to said charge, in

17. In the art of Xing nitrogen by cyanizing a charge comprising carbon and an alkali metal oxygen compound, which charge is capable of reacting with free nitrogen, at an elevated temperature, to form a cyanid of said alkali metal,-the improvement which consists in iirst heating the charge internally by a circulating heating current of gas having normally a high carbon monoxid content, vwhile substantially simultaneously catalytically obtaining carbon dioxid and carbon for in said current subsequent to the emergence of said gas from the charge being heated, said current being thereafter reheated to a high temperature, preparatory to its return part-at least by reacting upon carbon With oxygen, in the presence of the carbon dioxid laden current, and cyanizing the so heated charge by substituting therewithin a current of hot nitrogen for said hot current, said nitrogen current being passed through'said charge in a direction opposite to that of said heating current.

.18. The process of fixing nitrogen which comprises cyanizing a charge which includes carbon and an alkalinous metal compound, in a receptacle from which said charge may be dropped, by subjecting said charge to heat and reacting thereon with `free nitrogen, and then disruptively dropping said charge and subjecting thefragments thereof to a current of relatively cold nitrogen during their fall. l v

19. In the art of fixing nitrogen by cyanizing a charge comprising carbon and an alkalinous metal compound, which charge is capable of reacting with free nitrogen, at an elevated temperature, to form a cyanogen compound of said metal,the improvement which consists in first heating the charge internally by a heating current of gas, thereafter reheating said current of gas preparatory to its reentry into the charge, saidto form a cyanogen compound which is fluid at the temperature of said reaction and which compound renders said charge adhesive While the fiuid content of said charge .is solidifying at a temperature below that at-which said compound forms,-the improvement Which consists in unloading said charge, as a batch from said receptacle While the charge is still at a temperature abovethat at Which it becomes adhesive, and thereafter cooling said charge by flowing a current of relativel cool nitrogen in contact therewith to congea said fluid content.

In testimony whereof I have aiixed my signature, in the presence of two Witnesses.

GHARLEb P. HIDDEN.

Witnesses:

ROGER N. LOBDELL, HOWARD C. RIPLEY.

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