US1087900A - Metallurgical and chemical process. - Google Patents

Description

J. E. BCHER.

MBTALLURGIGAL AND CHEMICAL PROCESS.

APPLICATION FILED APR.15, 1912.

Patented Feb. 17, 1914.

LKQ.

u! J ,MIIEF MIXED STATES PATENT-@FFICE JOHN E. BCIEE, 0F COVENTRY, RHODE ISLAND, ASSIGNOR TO NITROGEN PRODUCTS OOMPANY, .A CORPORATION OF RHODE ISLAND.

MTALLURGICA-L AND CHEMIGAIIi PROCESS.

To all whom it may concern:

Be it known that ll, Joris E. Boonen, a citizen of the United States, residing at Coventr in the county of Kent and State 'of Rho e Island, have invented certain new and useful Im rovements in Metallurgical and Chemical rocesses, of which the following isa full, clearand exact description, This invention relates toa novel rocess of manufacture, one -aspect. of whie pertains to the purication of metals generally, and moreA articularly iron, with theformation of ot ier commercially valuable products and ley-products incident thereto.

1With the exception of'aluininum, iron is probably the most abundant metal in the earth, but its im ortant ores are nearly all oxygen compoun s. ln practice it is nearly always obtained by reducing these ores with carbon in a blast furnace, or the like. The crude iron thusobtained, known in the art as pig-iron, is very impure and frequently contains only about ninety-tivo per cent. of iron. rll`he impurities in the pig-iron consist of variable quantities of carbon, silicon, phosphorus. lsulfur, manganese, slag. occluded gases, and other substances. These impurities come partly from the ore and partly from the materials used in the nianufacture of the iron. During the past hundred years considerable progresshas been made in the removal of these impurities, but notwithstanding these advances in the art, really pure iron is not yet prepared on a large commercial scale. rlhis is due partly to the dimculty or expense of removing certain constituents from the iron. The processes of purification, which are now in use, such as the Bessemer, basic Bessemer, basic open-hearth. acid open-hearth, and pud- (lling` practially all depend on oxidation; the oxygen being usually obtained from the air or from iron ore (lFegOa) or its equivalent. or from air'and oxid; and'in substan-v tially all of these processes, oxygen is the active element used in the purification, and the. elements carbon, silicon, manganese, sul'- fur and phosphorus are oxidizedand thus eliminated in the escaping gases, `or else in the forni of slugs. llhese processes, while servnr admirably in many respects are atltendedj with many serious.disadvantages;

such as requiring the ores, the metal treat- Speciilcation of Letters Patent.

Adlication filed April 15, i912. Serial No. 690.888.

Patented Feb. 17, 1914.

be limited inmost, if not all of the methods vused at present, for economic and other considerations, the removal of the impurities is practically never complete; and in some cases these methods even result in `entire failure to remove the most objectionable inipurities. Slags are formed and these sonictimes interfere with the process. In some cases, excessive loss of metal or time is involved. In certain processes the energetic oxidation causes serious injury to thc metal and thus necessitates the use of deoxidizing agents such as manganese or silicon. Indeed, it sometimes becomes necessary to add somewhat expensive alloys or materizils'con taining such elements as manganese-o silicon, in order to maintain the required high temperature during the process of oxidation. When air, which contains only about one volume of oxygen to four volumes of nitrogen, is used asthe source of oxygen, an enormous volume of inert nitrogen is carried along with the oxygen necessary for the process. The large volume of inert gas thus introduced .into a given process necessitates the use of extensive pumping inacliiiiery and unduly large furnaces and conpound) comprising nitrogen (or a nitrogenous compound) and one or more powerful reducing'elements` such for example as the metals of the alkali or alkaline earth groups; or compounds of such elements. ln

4otherwords, l may use a mixture comprising nitrogen and one or more of these reducing elements, e. g. sodium and magnesium; or I may use a compound of nitrogen and one or more of these elements, e. g.

g ments are .'tility; while sodium has the a ded advan-V tage of cheapness. While these recited ele- Enferred, I do not desire, however, tojbe ited thereto in any sense, since any suitable material which may be characi terized as a powerful reducin agent, or element, isjregarded as within t c purview of my invention.

Thevrelative' proportions of the elements used inthe process may be widely varied,

and depend upon thenature of theimpurities present inthe substance treated, and the extent to which'it is desired to remove these impurities. Assuming that sodium be the metal. used, b way of illustration, so' little -thereof may some cases, that theA mixture, for example,

- with nitrogen may comprise but a trace of thesodium.. ndeed, 1n some cases the nitrogen may'- beused alone. This aspect of the inventionr is distinguished from the usual processes, in that, in such case, the nitrogen 1s theactive purlyin agent, in contradissubstantially of, for example, alkali or alka'- tinction to oxygen. sometimes .be desirable to use so little nitrogenous rmatter that the reagents will consist line earth metals. It w1ll be understood,

however, that while the sodium, for example,

may have inde ndent functions or actions 'of its own; enfin like manner the nitrogen may have independentfunctions, there is. yet av peculiar i'e ationsliipV between such eley ments whereby they conjointlyserve to veffeet decarburization of the material treated.- Considered from this point of view, therefore, the process, in so fares it relates to the decarburization of iron, for example, is practically independent of the se larate and Independent'functions of the re vcing element or. elements, and the nitrogen; and while it is almost inevitable-that ysuch individual constituent elements will act to some measure', in anyvcase independently, such action is incidental and unavoidable to their arate and inde combined action.l They claims herein accordingly do not attempt to cover these sepments employe ,"speciiically.

' which are reactive in my process and which will furnishin such case an alkali or alkaline earth metal,` and 1n some cases a certain involved in the process, in.

n other cases it will' udent actions of the ele-A may be used. Cyanamids, such as disodiuni cyanamid, and amids, such as sodlum amid,

which may be used in the process. The nitrogen used in my process lmay also be obtained from such nitrogenous compounds as ammonia, nitride, and the like, or mixtures of such substancesyand it may be, and in many cases preferably is, free nitrogen. If 'nitrids are used they may, if desired,be proi nitrid formin elements to the metal or substance which 1s to be treated.

Then vair` isinjected into molten iron, as in knownV processes, the oxygen is so much -more active .than the nitrogen that the latter is practicallyinert; as it is generally considerd. It is, hence, desirable in most cases, when conductingA my novel rocess,'to exclude air. It is also desira le usually to, as far as practicable, exclude water and water-.forming constituents from participaably present in' the substance to be treated or. urified, but such cannot-in many cases be helped; and all that can be done is to avoid thewilful-introduction of such com'- pounds as hydrates, for example, which contain certain water forming constituents.

that the principles. of my process for the urification of iron, and especially for the decarburization thereof, Jare distinctively differentfrom those of the present commercial processes.v These known processes, conand they'depend upon oxygen for the active' element, in'. the purification. 0n the other hand my process is a reduction process which /makes use of nitrogen alone in certain aspects. of the same, and of owerful reducing elements, such as the al tali or alkaline earthmetals, in other aspectsof the same, and yet/further, of a combination. of nitrogen or nitrogenous matter and such reduclng elements, the latter. more `particularly for decarburization purposes. -This distlnction is fundamental, as even the basic processes which are now in commercial use are really strictly oxidation processes in which basic material is used primarily toremove the phosphorus.

In my process free nitrogen, which. in the present commercial processes which. use oxygen of the air, is an undesirable inert element which avoided, not only becomes an active particlpa'nt in the reactions involved; bntvfurther, becomes fixed and absorbed morel or less completely to formtnitrogenous compounds such, for example, as c'yanogen. compounds or nitrids. On account of these radical diiier 1 ences my process. overcomes very many of I 6.5 amOlmt 0f nitrogen in addition, for example, i the disadvantages of those heretofore in use duced from nitrogen by the addition of' tion in the'react'ions involved in the process.' A certain amount of these'may be ,unavo1d-,

. The above statements conclusively show etc., are among the compounds of this type sidered as a whole, are oxidation processes,

cannot conveniently be for puriy'in iron and the like, end it also `has many ot ier und even more novel advantages. For example: itnot only allows thc fixation of atmospheric nitrogen with the production of cyanogen com ounds or nitrid's, as above stated; but., urther, it facilitates the production of ammonia, and similar compounds; while it etl'ects a saving of the carbon lpresent in the mass to be treated. .Thus instead ot oxidation products, such as carbon monoxid, carbon' dioxid,

or `carbonates, l obtain cyanid, for example.

' ,'lhi'svlatter production may be represented by the equations:

2Na+2C+N=2fNaCN+about 51900 calories 'llhese reactions are strongly exothermic;

and therefore may furnish a new means of getting the high temperature iiecessary in i1' modified Bessemer or similar process.

@wing to the tact that it is unnecessary in my process t'o heat up a relatively en'ormous bulk ot inert nitrogen, and owing to the powerful'exothermic reactions involved, it

should become possible for heating purposes,

to utilize the carbon, present in the charge, much more advantageously than in many known processes. My experiments have demonstrated that it is possible to augmentthis heating effect by the addition of carbon; whiletheheating effectwill still further be intensitied b v introducingr sodium or other suitable reducing metal in the form of a vapor,

- either alone, or in a hot gaseous orvaporous -ores are expensive, and the herein described process will hence 'probably enable 'the use of cheaper ores.

Carbon in any form, even as graphite, or as carbids. t. y. iron carbid, may be readily and completely removed -from iron by my process; or it may be removed to substantially any desired extent. Carbon or graphitized carbon may also be removed from a mixture of powdered or otherwise finely divided iron and carbon by vthis method. As to just what reactions and in` ter-reactions take place resulting in the carbon present., from whatever source. uniting with the nitrogen to form the radical CN, lt am unable-to positively state. Apparent-ly, an iron carbid, or, in some cases, a solution of carbon in iron, is first formed, which mnemoc 3 carbid, or solution, together with the iron Acarbid already present, it any, then reacts -to in any way. The removal of graphitic carbon is of especial importance. in that the presence of this, substance in iron materially 1mpairs its strength. litmay here be noted also that I find that carbon in other forms e. g. silicon carbid may be successfully removed by my process. Indeed not only is the carbon o -such a compound removed. but the silicon itself is also eliminated from the met al treated.

v,llhcsphcrus in Steel causes brittlcncss under shock and general cold shortness. lt

'has also been shown that even .003 per cent. vincrease 1n phosphorus decreases the wearing qualitiesl of the cutting edges of tools to a sensible extent; and in lgeneral, the presence of relatively minute quant-ities of this impurity seriously impairs some ot' the most valuable clulracteristics of iron or steel. Phosphorus is not removed to any extent by acid oxidation processes because the phosphorus pcntoxid formed is again reduced, thus re-phos )horizing the iron. It has therefore hereto ore been necessary to employ basic Vprocesses, such as the basic` open-hearth, or basic Bessemer, which are usually more troublesome, and in sonic casos, more expensive than the ordinary Bessemer process. The basic Bessemer process rcquires high phosphorus and low silicon on account of the basic lining, and further on account of the desirability of producing a high temperature and a slae,r rich in calcium phosphate. In my process, the phosphorus. so fa r as I have been able to ascertain. is completely removed, presumably in the t'orin ot' a phesphid. and as the temperature can be maintained by the formation of cyanids from carbon, .there is no need of a .definite composition of the iron used iu the process. The basic Bessemer process was invented especially to remove phosphorus, and I am of the opinion that my herein described process may aliord a substitute for it.

Sulfur is perhaps the most injurious iinpurity found in iron, and, to the best of my knowledge, no completely satisfactory coinlnercial method for its removal has been found. In some cases the percentage of sulfur in the metal is even increased during the eii'cctuation of known processes. This obstacle prevents the use of certain cheap iron ores, which contain too much sulfur, in the blast furnace. In my process the sulfur is removed, presumably asisulfid. If sodium `be the metal used, the following collation would represent the reaction:

As this reaction is also powerfully exother-mic` the sulfur is removed very energeticall'y and completely. This action is hence of very great importance, since sul- 1o, fur in steel causes red shortness, interferes' with welding, and,- therefore, may cause imperfections in apparently sound castings. I am also of the opinion that sulfur and' fphosphorushave been the cause of many of the mysterious failures of structural steel, and of many serious accidents -,due to the breakage of'railwayrails; and faults due to the same cannot always be.avoided,`

even by careful heat treatment; nor can they always be detected, even by careful tests or inspection. These facts demonstrate the value of-my processwherein sulfur, phosphorus and carbon, which, so far' as I am aware, cannot be removed completely by the commercial, oxidation processes of today without undue lcss of iron by oxidation, can be removed completely because the iron is not attacked by nitrogen, nor by the metals of, for example, the alkali or alkaline earth groups.'

In such a modified Bessemer process as I have referred to, said process would not need to be interrupted promptly at a certain time as the lnetal treated cannot become oxidized;

.85 so that the process could, in effect, bc forced tocompletion without danger to the product or products.' In the present Bessemer process it isv connnbn'ly necessary to add.

ferro-manmmese or similar Substances to i l0 take awa)1 the excessy of oxygen. In the contemplated process the current of sodium vaporand nitrogen should remove oxygen if it is present in combinations such as FeO, CO, and simila r substances, or in the form of sla'gS. Thus it should be possible to effecta recovery of iron, instead of having to" sustain a loss of about 13 to 17 per cent., as is` re' quently the case with thebasic'Bessemer process.

I have not been able, as yet, to ascertain exactly in what order the impurities are removed from the metal to be treated. but I am of the opinion that the objectionable elements sulfur and phosphorus. are among the first to be removed, rather than among .the last. If I am correct, this will result in a very great. advantage, since it should not then be necessary to remove all of the carbon and then to recarburize the iron as is done im known processes'.

I have above referred to the independent action of nitrogen in the process, and am o the opinion that the nitrd-forming elfments. such as silicon, titanium, vanadium,

and similar' elements, may be removed under suitable treatment, through the instru' mentality ofthe nitrogen alone; the reactions betweensuchl elements and the nitro-k gen probably forming nitrids.- Such nitrids maybe heated` with ,steam or with caustic alkalisJ or they may be treated by other suitable methods to recover the iixed nitrogen in the forni of ammonia, forexample. v.

I have previously referred to the reduced volume of gas which might be used in such a modified Bessemer process, which \should v ypermit of Ithe use of much smaller apparatus, such as pumping machinery, furnaces and converters, than are at present in use. This is principally dueto the fact that the volume of nitrogen required to remove carbon as cyanid is only'about twenty perl cent. of the volume of air required in the Bessemer process to remove the carbon as carbon monoxid.' T his percentage may vary-down 85 to none at all in the case of operations relating' to the removal of such elements as sulfur and phosphorus alone. The reduced volume of gaseous mattei' which would be passed through a. charge would also reduce spattcringof material and lcssof heat. e It. is also evident that my proc-ess may be used in conjunction with processes at present in commercial use, thus giving a combined oxidation-reduction process. or a combilled reduction-oxidation process. Iron may also'be recovered from slag, for cxample. by means of the herein described 'methodz the oxids being reduced at-proper temperat1 i1'es. The following equations loo serve., to illustrate lthis phase of my inven- Aaddition of carbon or carbonaceous matter t0 the molten metal; Theprocess mmY also be applied -to relatively impure umterials, such as metallic regulus.

-Inv large measure, v the 'blow holes in iron or steel are caused by carbon monoxid which is soluble in hot metal and separates partlywhen the metal solidifies, or which is formed by the reaction of oxids, such as FeO, in the slag with carbon. For example:

l FeO+C=Fe+CO The reactions almost immediately above'lu noeaooo 5 'recited will obviously prevent the formation ot carbon monoxid, provided the temperature be not too high; and it such substance be present it will be reduced with produc- 5, tion oit tree carbon as per the` following equations:

' C+2Na=ltla20+C oo-i-Mg=ngo+o lo' ll am et the opinion also that the nitrogen or nitrogen and argon current will displace or sweep out the carbon monoxid as Well as' @i M5 contemplate one use of the sa1d element 1n connection with the present process. I have v just stated that the nitrogen', or nitrogen and argon current lshould displace cr sweep out carbon monoxid and other gases and volatile w@ substances from the melt, andlmay here state that l contemplate in some cases using a current of substantially pure argon tor this purpose. The statements in the literature indicate that the continued existence ot mi vnitrogen in molten iron is very uncertain, and even should lt use the current of nitro- `een without any supplemental flow of relatively pure argon, llbelieve that the nitrogen `would in probably no' case be occluded in any materiat quantity in the molten metal.

Should it be found that any appreciable` quantit ot nitrogen is occluded in the metal, owever, it may be readily removed by the addition ot nitridforming elements. llt, may also, be removed by the additionot carbonv with sodium or similar elements which would form cyanidsaccording to the reaction:v m l Qhla-l-QC-l-NzzQNaCN f lt is obvious, ofcourse, that this phase ot my process `would applymorc particularly to molten metals, and especially to iron, and

it may be carried out in many tormsfot ap- M pa'ratus; Aconverters very similar to those used in the basic Bessemerpprocess being suitableg and l have hence not attempted to illustrate apparatus wherein this hase oit my process might be ed'ectuated. t should ll@ be borne inmind, however,i that in most cases air should be carefully excluded.

y l have successfully carried out my herein described process at teinperaturesbelow the meltingl vpoint otD metals which are to be @t purited, and will nour proceed todescribe with particularity the nature of the apparatus which ll have used in this connection.

lt is to be understood, however, that the said apparatusis but one of many by means of which my process may be carried out,'and l 7@ hence do not desire to be limited in any particular as to either the mannerA or means b or in which said process may be eectuate While vthe particular exempliication of my process hereinafter described relates 'i5 more particularly to the treatment. or metais or substances at temperatures helena" the melting point of such substances oirmetnls,

l reiterate that l regard the treatment or" metals or substances at temperatures above 'w their melting points as Within' the purview" ot my invention, and hence do not desire to be limited to operations conducted at rela tively low temperatures, except where the claims specifically so state. 'lhat this cong5 y tention is justified is practically 'proven by myexperinents wherein, in some cases, iron which 'l have treatedhas been `formed into `globules of substantially pure iron during the course of the cyanid forming operation. e@

Referring to the drawing which forms a part hereof' and in which like reference characters designate like parts in t-he respective views: Figure 1 is aside elevation ot an ap# paratus wherein my process may be carried or, out, one side ot the mulesurrounding the retort being. removed' for purposes ot illustration. Fig. 2 isa -section ot saidapparatus, taken on line lll-llt ot Fig.

section oi heavy Wrought iron pipe l loa is provided at either extremity thereof'WithV` .a reducing c ap 9, the reduced extremitiesA oi.

these caps being respectively connected to pipes 8 and l, preferably ot considerably smaller diameter than the section l. Afl" 'lor 5 is connected to the outer extremity ot the small pipe or nipple 3, and a nipple (i ot the same diameteriuay be tapped into the opposite side ot l 5. Nipple (i is'connected to a coolry 7, which in turn is connected vvto a 11o coupling 8.. The nipple or pi e section t is` also correspondingly connecte to a coupling 9. Two -Ts 10---10,- one of which is disposed upon either/side ot the retort termed by. the 4'tube 1 are connected respectively with the tit couplings 8 and 9. in any suitable manner, while a U-shaped'pipc connection 11, having 'therein a coup ingI 12 and cock t3, altord a by-pass around the retort. Down- Wardly extending from the lf 5 is a pipe 120 connection lll havim, therein a cool-z '15 and laterally 4extending` rom the l 10is a con nection 16 in which is a coclr 17. 'llhe retort V1 may be heated in any suitable manner, as

by means of a series ot Bunse'n burners '18, E25 which for convenience may be mounted upon a common base 19 in a well known manner. A mums or screen 20ct tire-brick, or the like, preferably having substantially the form et an inverted lll, may surround'the 130 carburized solid masses of steel in this aparatus: the decarburization being'so perect that I have been unable to find a trace of carbon after the treatment; while I have also successfully treated pig iron herein. The metal may be introduced into the retort by unscrewing one of the reducers 2, and I similarly introduce at one end of the re tort a quantity of some powerful reactive metal, e. g., sodium. Nitrogen is introduced into the retort 'via a pipe 24, which is in communication with the T 10, upon the left hand side of the device as shown in Fig.A

1; and if the cocks 7 an l17 be opened, and cocks 13 and 15 be closed, the gaseous nitrogen will pass through thecoupling 8, and connected parts, directly into the retort. Herein it is rapidly heated to a temperature preferably approximating the boiling point of sodium, if that be the reducing metal used. As the hot nitrogen passes over the sodium, designated 25,L the latter vaporizes thereinto and passes together with the nitrogen through or over the metal 23 to be treated.

In the device shown, twenty burners have been somewhat diagrammatically indica-ted, and in practice afew of these at the extremity ofthe retort from which the current of nitrogen emerges are unlighted. Thus for example, ifteen gas jets may be ignited, and five burners may be-left cold.

As a result, the said extremity of the retort from which the nitrogen emerges -is cooler than other portions of the same, and is preferably at a temperature below the boiling point of sodium, sc that an which passes 'through the mass o metal to be treated, e. g., iron, will, upon entering this relatively cool end` of .the retort, be c le-.

posited. This procedure results in 'a saving of the reducing metal which accumulates. in this relativel and is there eld until the current of nitro,-

n is reversed, in the manner hereinafter escribed. The nitrogenwhich 4passes through the' apparatus should prefere ly be iite pure, with the exception, perhaps, of

e argon wpresent, and )as it passes olf through the cock 17 it maybe collected in -an suitable manner t avoidwaste.- After sulistantially all of the sodium, if sodium sodium coo]` extremity of the retort be the reducing metal employed, has been transferred from one end of the retort to the other, the cocks 7 and 17 are closed and those designated 13 and 15 are opened. Thereafter the nitrogen' `will pass downwardly from T .l'and around a bypass 11 to T 10', and thence through the retort'l in a reverse direction to that in which :it previcusly fiowed therethrough. vIt will be'understood that before 'so reversing the current of gas the burners 18,' which had previously been unlighted, are now lighted, and a corresponding number at the other extremity of the retort are turned off. As a result,

the cool section or portion of the retort i's transferred from one extremity of the latter to the other, so that the previously deposited sodium, for example, will be revaporated and will again be carried through or over the metal to be treated, by the nitrogen current, to bedeposited thereafter at the end of the retort from whence it originally came. Theow of nitrogen throu h the retort-may thus be reversed at interva s until the metal to be treated has been substantially completely purilied, or until all of the reducing metal has been used up. It is obvious that this metal may be introduced into the re- 'tort or vessel either inliquid'or in solid form, or it may be introduced as a vapor;-

My experiments indicate that the higher the temperature of the operation, the more rapid the efectuation of theprocess. There 'are probably, however limits beyond which it would be undesirableto go.' In operating the apparatus herein particularly described, the temperature was maintained by means of'the burners' at from 700 to 800 C. I

Was-melted into globules, which would indicate thatthetemperatureof some of the ironhad been .raised to the neighborhood of.'

"1200o G., at least, and robably to '1500o C., 'or more. Under 'these ast mentioned condiv'tions the demand for nitrogen is so great that -a .rapid stream of thesame must be flowedv into. the retort s thereactions tend to form a partial vacuum therein, and it is necessary 1n such' case' further to guard'l .againsta flow of g'as back through the cock 17.. To'this end, a Vliquid seal 26, or the portions 'of atmospheric nitrogen, lcar on and sodium in the' oregoin case, the small -quantity of gas escaping t rough the tube 29 was practically purev argon, substantially eefdily all 'of the nitrogen having been absorbed. lArgon may. only be obtained, of course, from atmos heric= nitrogen, and it ,i's

assumed that this tter'has been obtained ducing metal.

- tained therefrom 4by lixiviation, cyanid bei' by separating it from the oxygen of the air by any suitable process, of which several commercially practicableI ones areknowu to me. Where an excess otnitrogen passes through the apparatus, it may, as I have previously stated, be collected; and may thusl be used repeatedly until it has all been consumed. Should it be found in practice that any waste of sodium, for example, is taking place, it is merely necessary to refrigerate, as by means, for example, of currents of air, the extremity of the retort from which the nitrogen flows, to such an extent that the temperature of the same will be materially below the boiling point of the relt may' be here observed, too, that it is advantageous, in some cases, to carry out the process under a pressure considerably above atmospheric. .This fea-y ture 1s of especial advantage, for exampler when the nitrogen current must be forcedV through the metallic mass being treated.

l have found that steel treated by the herein described process is much less rapidly attacked by hydrochloric acid (20% solution) thanit originally was, the steel and the iron, as it really becomes, being respectively subjected to the acid at` a. temperature from 80 to 90 C. ln other words, ll have found that the, ractically pure iron produced by the herein described recess 'dissolves very slowly in said acid an is far less subject to corrosion than untreated iron. It is obvious also that castings may be treated in accordance with the said process so that the carbon may be taken, if desired, only from the outside thereof. virtually rendering the outside of the castings malleable. When the metal treated is in solid, or relatively solid form, the action seems to be that the carbon in whatever form it is present diffuses from the` interior portions toward..

the surface of the metal, there to re-aot with the nitrogen and sodium to form cyanid. lron. is completely decarburized when heated to redness in an atmosphere ofnitrogen and sodium vapor for a sufiicient length of time, substantially pure sodium cyanid being formed The process may even be used to separate a mixture of finely divided carbon and iron in the form ot filings, powder and similar states of division. When the operation is conducted at 'or around a red heat, the cyanid will collect u'pon the surface oi the metal treated, and can readily be obing very soluble in water, and but a small quantity of this latter fluid' therefore sufficing to expeditiously recover this valuable product in the Jform, if desired, of a concentrated cyanid solution.

In treating solid bodies of iron suchv as castings, for example, obviously the carbon only at the surface of such bodies-1s first removed, but as the process 1s continued it is progressively removed from the inner portions of the castings, ortho like. -It is possible, therefore, to produce: a materialconsisting of initially integrally connected layers of iron and steel, for example, which may even be alternated, since it 1s possible vto recarburize a.' surface by known cementotion processes. Thus, for example a block of. steel may be' at least partially decarburized to a given depth, of, let us say, onehalf inch. Thereafter' it may be recarburized by known processes to indepth of, let us say, one-quarter of an inch, and then by n?, herein'- described process a portion only o this recarburized iron may he again partially decarburized for example, to a .depth of one-eighth of an inch, and finally the surfaceonly may be recarburized again, if

desired. Again, other material than carbon mayy be introduced into.- the `decarburizecl metal. rlhus vapors, for example, contain- -scribed,the product isa spongy mass, which or when compressed appears as a shining highly lustrous, coherent, 'metallic substance which is very soft, being readily hammered or worked at ordinary teni eratures.

readily compressed that it becomes coherent and lustrous even when rubbed merely with a horn spatula, or the finger nail. 'Such finely divided sl onge-like iron may be molded, compressec, hammered, or otherwise suitably worked', with or without the assist, ance of other substances, such as carbon. The objects thus formed may then be given any desired heat treatment, thus forming by molding processes objects equivalent to castings, pipes, ingcts, sheets and bars of any desired composition.'

Steel vand other objectssuch as sheets'of metal, wire, bars, nails, or posts, may be treated by this method so as to soften or purify the surface layersalone, by selecting,A

The spongy material above rc'erred to is soA los suitable conditions 1n accordance with th'eforegoing, the surfaces to be treated being brought into Contact, for example, --with sodium and nitrogen, and the 'articles being heated for a suflicient lengthiof .time to per mit of decarburization to the-desired amount l and depth. lf'desire'd, iron or steel objects thus treated'ma'y be givena'ny desiredsub- .sulfuri'zat-ion, are completed dep'eudingon thejrate4 of dilusibnlof'such impurities 'las from sheet 1ron before or sherardizing, as it removes not only the' through the solid mass to be treated, at the tem erature of the operation. The metal surace thus obtained is very resistant to corrosion. This phase of the process is` espe cially adapted'for the removal of impurities tinning, galvanizing usual impurities, but also the comparatively large quantity of phosphorus which is present in the metal to reve'nt too great stickiness of thesheets 1n the-rolling processes. The metal so treated' is, therefore, free from the greater part of the impurities which at present cause so much corrosion of tinned iron.

The value of the herein described process will therefore be almost self-evident, and it is anticipated 'that it will have an` importaut effect upon-many industries. Inview of the importance of the said process, and in view of the novelty residing therein, I hence desire to be limited only by the scope of the appended claims. In certain of these claims I have referred to a rocess of manufacture which includes e ecting a reaction, etc. Such claims I desire to be regarded as v of suicient scope to relate not only to a iron.

purified metal, s. g., iron, but to other products of the treatment and of the reactions involved, e. g., cyanogen com ounds. It will further 'be understood that t e word purifying as used herein is a general term and isintended to'cover either partial orcom plete purification; while the term iron as used 1n thev claims in connection with the: vsaid word-purifying, or words of slmllar import, refers to wrought iron, cast iron, steel, and the like, or to alloys containing In like manner' the ex ression changing the physical condition of a compound is intended to cover volatilization, lixiviation,`etc. Where the word reaction oc# curs in said claims, unless qualified by the adjective direct, or the like, I intend it to be unde stood that such term not only includes a lsimple or direct reaction but a 'complex reaction wherein possibly several subsidiary reactions occur; this provision be! ing obviously'necessitated -by the lack of exact knowledge asto just how the molecules of the several elements involved behave with respect to each` other'. In the appended claims the term light metal has been-used as a generic term for such metals of relatively lowT specific gravity aS sodium,

potassium, barium, andthe like. Where, also,

' incertain of the claimsthe reactions set forth involve -iron or its equivalent, it is to be understood that in such case the ironniay actively. participatein the reaction, z'. e. enter into orbe removed from chemical compounds, as in the case of carbid, or it may participatercatalytically, as the case where it acts as a solvent for thecarbon in least, thereof intimatel the manner previously referred to. In other words, such claims'are to' be regarded as ofv sufficient scope to cover iron, or its equivalent, either as an active participant'or as a catalyst. The term metal of the iron group used in certain of the claims is "in-v tended to cover those metals commonly regarded in analytical work as properly ertaining to the grou e. g; manganese, c romium, nickel, coba t, etc.

Having described my invention, I claim: 1. The process. of purifying a metallic mass having impurities therein, one of which comprises carbon, which includes heating said mass and bringing. portions, at least,

thereof intimatel into contact with nitrogenous matter an a' powerful reducing -element, and effecting a reaction between some of said 4carbon, mtrogenous matter and reducingelement, and also effecting another reaction between some of said 4reducing element and anotherv of said impurities with which said reducing element 1s capable of directl uniting.

2. T e' rocess 'of purifying a metallic mass having impurities therein, one of lwhich comprises carbon, which includes heating said mass and bringing portions,'at into contact with nitrogenous matter an a powerful reducing element, and effecting a reaction between someof said carbon, nitro cnous matreaction between some of said reducing element and another of said impurities'with which said element is capable of directly uniting, and eecting still another reaction betweenfsome of Asaid nitrogenous matter and another of said impurities with which nitrogen 1s capable (if directly uniting.

'4. The process of purifying a metallic mass having impurities therein, one of which comprises carbon, which includes supplying nitrogenous matter to said mass and effecting a reaction in which the element nitrogen and some of said carbon participate-to form cyanogen. v 5.- The process of purifyingl a metallic mass having impurities therein,one of which comprises carbon, and one of which comprises an element capable of being united noarpoo n with nitrogen to form a nitrid, .which in clndes supplying nitrogenons matter to said mass and effecting a plurality of reactions in which the element nitrogen and some of said impurities participate to form nitrogenous compounds, carbon taking partin one .of said reactions and yielding cyanogen.

6. "llieprocess of purifying a metal which comprises effecting a reaction in which the metal to be treated, a powerful reducing eieinent, the element carbon and a ni'tiroggenous compound participate.`

7. The process of treatinga inassvofmaterial containing carbon in solution in an clement normally incapable of'di'rectly unittlierefrom, which comprises effecting a reaction, at an elevated' temperature, in Which at least some of said carbon, the element nitrogen, an element capable of acting as theA base of a compound containing carbon and nitrogen, and said first-mentioned element participate to form said compound,said nitrogen being present previous to said reac tion as an element of an inorganic nitroge- .nous compound.

' 8. 'llie process of treating a substance containing carbon-in solution in an element ot the iron group which-is capable of directly uniting Witl'i free carboinwhicli cornprises combining a portion at least of said carbon with nitrogen to form cyanogen, and

with a second velement capable otacting as thcbascof al cyanogen compound,l by bringing said second element together with a nitrogenous compound, into intimate contact with said substance, and elevating tbe teinperatnre of said substance to a point where substantially all of said carbon may be reacted upon by nitrogen obtained in part at least :trom said nitrogenous compound and by said second element totorm said cyano-` gen, compound.

9.V The process of treating a vmass of inaterial containing carbon in solution in an element normally incapable of directly uniting wit-l1 :tree nitrogen, to separate carbon therefrom, which comprises ett'ecting a reaction, at an elevated temperature, in ivliicli at leastsome of said carbon, the element nitrogen, an element capable of acting as the base cfa compound containing carbon andnitrogen, and said first mentioned element, participatetoY form said compound, said nitrogen beingv present previous to said reaction, as an element of a nitrogenous com pouiid. Y

l10. The process ot ,treating a mass of inaterial containing carbon in solution in an element normally incapable of directly unit.-v

ing with free nitrogen, to 'separate carbon therefrom, which comprises effecting a Treaction, at an elevated temperature in which atleast. some of said carbon, the 'element ni ing with free nitrogen, to separate carbon' trogen, an element capable of acting as the base of a compound containing carbon and nitrogen in the form of a radical, and said first mentioned element, participate to form said compound, said nitrogen being present, previous to said reaction as an element of a nitrogenous compound.

11. The process of treating a mass of inaterial containing carbon and an element cabut incapable o directly uniting with free nitrogem. to separate carbon therefrom, which comprises effecting a reaction at an velevated temperature, in which at least some of said carbon, the element nitrogen, an initially free element capable of acting as the base of a compound containing carbon and nitrogen, and said first nientionedelenient, participate to forni said compound, .said nitrogen beingr present, previous to said reaction, as an element of a. nitrogenous compound.

terial containing carbon and an element non inally incapable of directly uniting with free nitrogen, to separate carbon therefrom, which comprises effecting a reaction at an elevated temperatu1'e,in which at least some compounds, an element capable of acting as the base of a compound containing carbon an'd nitrogen, and said first mentioned elernent', participate to 'form said compound.

13. The process of -treating a mass of material containing carbon in solution in an element capable of directly uniting with free carbon to forma carbid, to separate carreaction, at an elevated temperature, in .which lat least' some of said carbon, a nitrogenous compound,an element capable of acting as the base of a compound containing carbon apd nitrogen, and said lirstmenform qsaid compound.

d5. The process of treating a mass of material containing carbon and iron, to sepa- .rat'b carbon tbenefrom, which comprises ef,-

vfecting a reaction at an elevated temperature .of said carbon, a mixture of nitrogenous,

bon therefrom, which comprises eiiecting a' pable'of directly uniting with free carbon,

, 12. The process of treating a mass of inai said rst mentioned clement, participate to f in which at least some of said carbon, the element nitro en, an initially free element capable of act ng as the base of a compound containing carbon and nitrogen in the form of a. radical, and iron participate, said nitrogen being present, previous to said reaction, as an element of a nitrogenous compound.

16. The process of treating a mass of ma.- terial containing carbon and :inclement of the iron group, to separatacarbon therefrom, which comprises eiecting'a reaction, at an elevated tem erature, in which at least some of said car on, a nitrogenous compound, an initially free element capable of acting as the base of a compound containing carbon and nitrogen in the form of a radical, and said element of the iron grou participate.

17.- The process of treating a mass of material containing carbon and iron, to separate carbon therefrom, which comprises effecting a reaction atan elevated temperature in which at least some of said carbon, a

nitrogenous compound. a light metal capable.

of acting as the base of a compound containing carbon and nitrogen in the form of a radical, and iron participate.

18. The process of treating a mass of niaterial containing carbon and an element normally incapable of directly uniting with free nitrogen, to separate carbon therefrom, which comprises effecting a reaction at an elevated temperature, in which at least some of said carbon, the element nitrogen, a light metal capable of acting as the base of a compound containing carbon andnitrogen,A

and said first mentioned element, participate to form said compound, said nitrogen being present, previous to said reaction, as an element of ay nitrogenous compound.

19. The process ofttr'eating a mass' of material containing carbon'iand an element normally incapable of directly uniting with free gen, which comprises subjecting said mass of material to heat, bringing a n itiogenous compound and a powerful reducing metal, capable of forming the base of a cyanogen compound which is stable at the temperature of. the operation, into intiinitevcontact with saidiron and carbon, and effecting a reaction in which portions, at least of said carbon, the nitrogen present in said compound thereof, said owerful reducing metal and said iron participate, to form said cyanogen compound of lsaid reducing metal.

21. The process of treating a mass of material containing iron and carboirwliereby y to combine portions at least of said' carbon with nitrogen, which comprises subjecting said mass of material to heat, brinving a. nitrogenous compound land a power ul reducing metal, capable of forming the base of a cyanogen compound which is stable atv which comprises carbon, and one oft' which comprises an element` capable of being directly united with a powerful reducing element, -which includes supplying said last inentionedelement and the element vnitrogen to said mass and effecting a plurality of reactions in which said powerful reducing ele-- ment and some of said impurities participate.,to form compounds of said reducing element, carbon taking part in one of said reactions and yielding cyanogen, said nitrogen being supplied to said reaction from a compound thereof;

23. The process of removing impurities from a 'substance which comprises 'eiiecting a reaction in which the substance to be treated, a owerful reducing element, the element car on, and a compound of nitrogen participate. p

24. The process of removing an impurity from a substance which comprises subjecting said substance to contactwith aI powerful reducing element in vaporous form, and effecting a reaction in which the substance to be treated, said reducing element, the

element carbon, anda compound of nitrogen participate.

25. The process of manufacture which in- Y cludes effecting a reaction ata. temperature above 500 C., in which an initially free element capable of being combined with carbon and nitrogen to form a cyanogen compound,

stable at the temperature of the operation, the element iron, a nitrogenous compound, and carbonaceous matter in non-gaseous form, participate, substantially as described.

26. The process ofmanufacture which includes-effecting a reaction, through the instrumentality of heat, in which a metal ca- -pable of bein combined with carbon and nitrogen to` orm .a cyanogen compound,

stable at the temperature of the operation, a. nitrogenous compound, an element of the iron group, and carbonaceous matter in nongasebus form participate, while substantially excluding water and water forming constituents from participation in said reaction.

27. rIhe process of manufacture which includes eecting a reaction, through theV instrumentality ofheat, in which a metal capable of bein comblned with carbon and nitrogen to orm a cyanogen compound, stable at .the temperature of the operation, a nitrogenous compound, the element iron, and carbonace'ous matter in non-gaseous form. participate.

28. The process of manufacture which includes effecting a reaction, through the in .strumentality ofheat, in which metallic sodium, a mtrogenous compound, an element of the iron group and .carbon uncombined with oxygen participate, while substantially excluding Water and Water forming constituents from participation in said reaction. i

29. The process of manufacture which includes eii'ecting a reaction, through the instrumentality of heat, in which metallic sodium, a nitrogenous com ound, the element iron, and carbon uncom ined with oxygen participate.

30. rThe process of treating a mass of macludes efecting a reaction,

t-erial containing carbon and iron to se arat carbon therefrom, which comprises eiicting a reaction.l at an elevated temperature, in which at least some of said carbon, and inorganic nitrogenous compound, la light metal capable of acting as the base of a compound' containing carbon and nitrogen in the form of a radical, and iron participate.

31. The process of manufacture which includes effecting a reaction, through the instrumentality of heat, in which metallic sodium, nitrogen initially present as a constituent of an' inorganic compound, the element iron, and carbon participate.

32. The process of manufacture which inthrough the instrumentality of heat, in which anv alkali metal, nitrogen initially present as a constituent of an inorganic compound, the element iron, and carbon particlpate.

33. The process of mapufacture which includes effecting a reaction, through the instrumentality of heat, in which metallic sodium, a nitrogenous compound, the element iron, and carbon participate.

ln witness whereof, l subscribe my signature, in the presence ol two Witnesses.

JOHN E. BCHER.

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