US2319402A - Desulphurizing apparatus - Google Patents

Description

R; P. HEUER DEsULPHURIzING APPARATUS Filed Jm. 18, `1941 4 sheets-sheet 3 Myl, 1943 Y 7 RLP, HEUER i 2,319,402`

DESULPHURIZING APPARATUS f Filed Jap. 18, 1941 `4 sheets-sheet 4 zo ya 6.o Y do 10.0 /zo 14o Jaa ao m i g' nella., "Research `Aly-invention relates tovan apparatus for the reatmentof `pig iron andthe production of l i 1 me, This applicationfisa continuation inpart fimyf cope'ndingA application Serial?` No.` 304,484, 5 "edQNovemberv, 15, 1939; for ap@` 1 paratua and procesa; which fresulted in `Patent 042,290,961, issued July.28, 1942; t `The" apparatus claimed herein nndsits treat stus'efulness iniconn'ecti farcoke blastlfurnacetoproduce pig ironhigher f f i. sulphurthan thatultimately deslred."andjpref.

` `erably `atfalovver costthannormal'. by operati nggmthe i'blastwiurnace; rat a lowertemperature awjl lmaterialrcausing higher `sulphur in;` the barge. IItJ facilitates treatment `oilthe `molten` i igfl ironthus produced witha basic slag externalo` thelblast `furnace hearth,` toliremo' ef-the eX-jv i ess sulphur from the molten pigirona ron `thus produced/ma! be usedfin thefform'of cast` iron `or as raw "materialforfmakinfg lanci'` course, capable ofi` usein de'sulpliuriaa-Yl 1",loiothex' metals.`

i Oneof `the purposes of my n videa refractory linedfdesulphrizingfladle Ywhose xisof *symmetry isi* vertical tojcontain1xiioltenij heqmolten ironyandi to `provide apparatus to` f m *horizontal plane`,whi1e desirably valso producp ngi irelative movementbetween th lag'" aridQthe` A H i Y i A, i rotate" molten iron AorV basic desulphuriaing slag` 35 ncontact withthe iron by an'impelleror preferblyfa plurality otlmpelle'r's 4turningjon"a verical axis andfprefe'rably` in a"ladle \lvhs`e `axis t o symmetry is vertical. The impellerswili prefatants'lag in-a ladle havingfiteaxis ofgnsymmetry substantiall'yverticaland to produce fromp ionwinthe iron to brin'glthe impurities ron into contact withthe slag, A i 1 y `Aifurther purpose isto provide ;iv`.pp`ara`tnY to `1`a`.gita.te molten pig iron in-thepresence'of` asu-l mythemagnetic action and` separately to lcirculatethe l lagin a different direction. i' y @A further purpose is to provide apparatusto im was t i f i bath,` the'slag being oppositelyirotated( .i

n'wlth `:the operation` "flo H rid/,or withlessbasic slag and/or withlow grade l5) 'I'hvnileo i p p i invention. The forms fshownhave` been chosen from Ithe standpoints of ,A satisfactory operation t andv convenientillustration ofg the principles in- Y. volved. 'All onthe nguresarediagrammatic. inven ionistopro- 25 Y A p section of avdesulphurizingvessel in accordance il'QIlHiflth abasic desulphuri'zingslag'fioatlngpn p i i s 4 yfwfligure 1a is a partirotary `motion to the metaLdesirablyin 30 :further-I purpose `is to provide "apparatus tol` u herotary movement of the iron, a verticalin'o"` i5` p Figure 9 isja is a fragment showing;` a modiiied 9 form ofdam applied to the structure of Figure 8. Figure. 11" is agfragmentary top planwview of Lyr'igureio. n, y i 1+ Figure 12 is a fragmentary central vertical pex'natant` slag in la. ladle by means ofelectro-` `5`0 g x Figure '.10

l whirl a pig iron bathrlby `horizontalrotaryrelec-n; romagnetic stirring and tomaintainf a substan-v `55 Aof"VV molten l on; the

`Furtherv purposes zappear in theaspecincation andintheclaims.`

` The present application incorporates freier-1 ence myUnited States patents andipatentfapplication', `Patent. No. 2,110,0`66pgranted'March l. i 1938,` for Iron and steel desulphurization; PatentA i No. 2,110,067, granted March1,19385i'orlron"` desulphurization; Patent Noi-2,177,716, granted A October` 31'.` 1939, -:for Desulphurlzing apparatus Patent No; 2,193,593, granted March 12, 1940, for Iron desulphurlzation; and Serial` No. 304,484,`

nled November, 1`5. V1939. resulting in lPatent No. 235161.11151,` granted July 28, 1942, forDesulphuriz-` ing: apparatusv and process. Reference should be therdisclosure ofthe process.

. 'In thedrawings no attempt hasl been madeto illustrate allot thepossible embodiments of the,

lliguxe` 1 fis ,a diagrammatic central vertical with the! present.: invention, vlith cooperating structure.` i .t i i fragment of Figureishowing Vcovers?applie'dnoverfY theopenings@Y A 2ris.a"central vertical section of one i form of stirring impeller in accordance with the i invention.:` `l i v i i i l i i f AFigure 2li-shows a diiferentlength of impeller 'extension fromthatshown in Figure 2.' g

\ Figure31i`s a "sideelevation of a variantform` p w i ofistlrringimpeller in accordance with the inveni tion; v Y i e t Y u f AFigure i` is aside elevationof affu'rtherV variant 4formof"stirring impeller. i

rablyiturninthesame directionp 40 `Awfurtherpurpose is to provide `"apparatus to vFigure 5 iisasection of Figure "4 on'thefline otate molten iron inthe presenceof `a"s`uper l-lf i f 'Figured is a-diagrammatic central vertical sec- -tionof ja' modifled-form-of desulphurizing vessel. i

- Figure 7 ris'a`.\s'e`ction of Figure on the `line i Figures is a central vertical section of a further modification in the desulphurizing vessel.`

section of Flgure along the'line yters the desulphurizing vessel.

section showing a further modication in the dam of Figure 8.

Figure 13 is a central vertical section of a further modification in the desulphurizing ves sel.

Figure 14 is a section of Figure li3 on the line Id-IL Figure 15 is a side elevation of a modif-led form of desulphurizing vessel with an electrical. diagram of a polyphase inductor coil applied thereto, the magnetic core being sectioned away Ior convenience in illustrating the coil.

Figure 16 is a section of Figure 15 on the lin'e I6-|6.-

Figure 17 is a diagrammatic top plan view of a variant form of electromagnetic':v stirring ladle.

Figure 18 is a fragmentary side elevation of Figure 17.

Figure 19 is a diagrammatic horizontal section of a modified desulphurizing vessel.

Figure 20 is a curve showing the rate of sulphur removal from pig iron under special controlled conditions.

In 'thel drawings like numerals refer to like depth of metal of 60 inches or more is to be expected. Thus for a depth of 60 inches, an elapsed time of 720 minutes or 12 hours would be required to desulphurize to the above extent. This time is too long for most operating conditions.

The rate of reaction can be speeded up appreciably by agitating the molten metal and/or the slag in order to produce relative motion between the slag and the metal at their point of contact, the so-called slag-metal interface. It is believed that the slow speed of desulphurization which is obtained in a `quiet bath is due to the resistance which the sulphur encounters in the regions closely adjoining the slag-metal interface whilst passing from the metal to the slag. When contact is first established'between the pig iron and the To take advantage of this accentuated desulphurizing action at higher temperature, I place the desulphurizing vessel in a position adjoining the blast furnace. In this manner I avoid any temperature loss such as would occur if the mol- -ten iron from the blast furnace is rst placed in a transfer ladle and then transported to a desulphurizing vessel located, for example, at the mixer in the steel making plant.

Contaminations caused by impurities containing silica are to be avoided and this can be effected by passing thevmolten iron through a small tea-pot ladle or similar device just before it en- In this Way the siliceous impurities are separated and the desulphurizing slag is kep uniform with as high a ratio ofv lime to silica as intended.

Agitation of the desulphurizing slag and molten pig iron is necessary in order to cause the desulphurizing reaction to proceed with convenient speed. The present inventor has performed experiments without agitating the molten slag and molten pig iron. Figure 20 shows the rate of sulphur removal under certain xed conditions, using a slag consistingof blast fur.-

v nace slag, 30% iluorspar and 30% burnt lime,

without agitation. In this gure the molten pig iron contained 0.07% sulphur atthe beginning of the experiment. This iron was treated with desulphurizing slag of the composition just noted under deoxidizing conditions and freedom from air contamination, and samples of iron were withdrawn for chemical analysis at specified times. In Figure 20 the experimental data has been plotted in a curveshowing, as the ordinate,

slag, the slag rapidly absorbs sulphur but the reaction soon slows down because, without agitation', the system approaches equilibrium only in the limited region which is not too far removed from the slag-metal interface. By providing a relative motion between the mass of the slag and theiron, thereby bringing fresh slag and iron into the zone adjacent to the slagmetal interface, it ls possible to speed the removal of the sulphur. By continuing this process of relative motion the diillculties of slow speed operation as described above in quietibaths can be overcome. The present invention is concerned with agitation to produce relative motion between the slag and the metal in order to speed up the reaction and obtain a higher content of sulphur in the slag and/or a lower content of sulphur in the iron than would otherwise be obtained.

Figure 1 illustrates a `desulphurizing vessel 20 equipped with a mechanical agitating device for obtaining increased relative motion between the molten pig iron and the supernatant slag. Such a vessel might contain from 40 to 200 tons or more of molten pig iron. The slag layer might approximate 1% to 10% or more of the depth oi' the molten iron. The shape of the vessel is approximately circular or oval in cross section and the axis of symmetry, that is, the axis running perpendicular to the plane of circular or oval cross section, is vertical. 1

The vaxis of symmetry as referred to herein will be what is commonlyI called the major axis in the ordinary case. Where the ladle cross section isl shell 2|r substantially gas tight and capable of.

protecting the contents-from access of the atmosphere or other oxidizing gases. The refractory lining 22 consists preferably of carbon or magnesite bricks which have suitable resistance to the corrosive action of the ladle contents. In order to conserve heat, these refractory bricks may be backed up with refractories 23 having lower thermal conductivity, as for example iireclay brick having an appreciably larger percent of pore space than normal for such products. In some cases flreclay brick may also be used in direct contact with the contents of the ladle, as for example in the lower part where the slag does not come into contact with the fireclay refractories for long periods of time.

A roof or cover 24 is provided for the ladle. Flreclay or other suitable refractories 25 such as carbon or magnesite can be used in lining this roof. The roof can be supported by hangers or other suitable means (not shown) from the external steel shell 26.

An opening 21 is provided for charging the `There are several advantages i y t siagneA f molten` iron and slag. Usually the slag willlbe fchargedbefore'the molten iron althoughuthis `is not always critical; LIhe ironwlll bettappedfrom theblast furnacev or othersourceiof supply f through a runner `28. zwIn ordertozprevent 'silica and other undesirable impurities fromrentering `thedesulphurizingladle, a; skimming ladle is provided. The iront` leaves. the: runnery "and Jentersthe open top of the skimming `ladle at4 3U. :.This ladle is provided with adam or skimmer ll. The molten `iron` passes beneath this skimmer andgthe flatingjimpurities arevheldxback at 32.A

Theexitend of theskimmlng ladle' lspro`vlded with'a cover 33 which `redicesaccess ofair to he interior of the treatn'ientladle.v After the .alsomade of carbon refractory or `may be made of so-called sillimanite refractory or `other high 4aluminous material. Figure 2a showsa different length of extension I8'. The impeller'assembLv lisfcax''ied on` the rotatingxshaft 41 whichmay fbemade of asuitameheat resistant metal with ,a `hollowinterior I8 into which cooling air or v 'other nula 1s blown by s. suitable pipen. :The t Anotherform ofimpellercapablejof lifting'pig impeller, extension and shaft z me` desirably threaded wone another4 at so and u.

iron is shown in Figure 3; In this case the im*- `peuerA headu' is desirabiyfmade or carbonfrdesulphurizingladleisproperly filled, the source ofmolten iron is cut off atitherunner. 'I'he iron still remaining intheskimming lad1evispoured into the desulphurizing ladle by tiltingqthe skim-` mer `about the trunnionl 3l. ThereuponV 4the Anlopening 3G is providedin the cover of the ladle for animpeller L31. `impeller is preferably a self-contained unit; having an electric motor 3B and speed reducer 39. `The motor `will;preferalznlyfbe a variable'speed `direct current motorproduclng .an impeller speed of 50 `to200 revolutions i, `per minute or more. The speed chosen may vary. with' different instal1ations.` Thewimpeller and i its;` operating." mechanism co- `@operate with ythe 'cover 24` to reduce access `;of fair atthis point and may beN removed as VYaiumt l from the desulphurizingi vessel and ya "cover 40` g substitutedas shown in Ilgurefla.` .i i i `ladle whose axis-of symmetryis vertical for de-` fsulphurlzlngtpig iron. .L 'Iliisxfmakesl` it possible `to locate thevdesulphurzing slag at. thel level of v in employing a. i

fractory. It isattached to the rotating. mechganism by means of-a sillimanite. cyaniteo'r other extension lili 'Ifile carbon `"r.efra'ctory `is mat chined to" provide a spiral fluting y52.` Theginiy i 2o: skimming `ladleancl coverlarellremoved and a.

n suitable permanent `cover I5 is placed on i the adle to cover the opening 21 as shown -in Fig-` Vurela.

:'peller vis mounted that the spiral fluting pref-` erablyextends into the Die ironand below the slag-metal interface, The rotation ofi the stirrer produces `acorresponding rotary movement in the slag and metal with which it isin contact. IBy virtue `of the flutin'g,` a vertical motionr is also produced whichpreferably lifts the iron and the slag abovethe level which it `would V@nxarrnally takeif` the iluting `were absent. The `eiect'offthelpumping `lnipller is"to lift `the `up thefsulphur removal.

moltenmetal `from the bath `and bringit into i ,netter contact with the desulphurizingglagthere@ by exposing fresh slag-metal interfaces to speed An` alternative apparatus for producingthe required agitation isv shown in -Figures 4 and 5.

This consists lof arotating stir-rer of carbonor t other suitable refractory which is supported by 4l a sillimanite extension It fas shownA in Figures maximum ladle `crosssec-tioniwith utilizationiof full ladle capa.city.l"Thus the slaggmetal interf` face is of `xnaurixnumareal fora convenient refractoryis'tructure. Refractorywrepairs and replacements are` much easier inni.` ladlewhose p axisof symmetry is vertical than in one whose t axis; of symmetry :is horizontal.` `In a normal *ladle whose axis ofsymmetryislvertical, a 'larger `proportion of i the pigqiron willfbe at` relatively greatl depthin the ladle than'in a ladle whose faxistof symmetry is horizontal. `Q'Zl'herefore t in a ladle 4whose axis of symmetry isgy vertical/there tis'greater importance in securing emcient stirring and stirring which islleective from the standi `point l of desulphurization.` i Y ,Differentwtypes'offim" llers-lmay be to y `irnpartfstlrrlng `primarily in Aahrizontal plane,

but with an upward stirring"component.` Fig?,`

urepZ shows a pumping.typeotfimpeller of cir-` `culacross section madesuitably oftcarbon re-` p A fractories.4 The jbody of the "impeller `Il "has pumping passages 42 extending diagonallyupiward and `outward shown; t The numberfof pumpingjpassages `42 isnot critical.vi'1'he effectv u of the pumpingimpellerfis to lift molten metalenV t from the bath into contact .with the desulphurizing slag. i The inlet 43 Vof the l pumping impeller willwpreferably be located` below the slag-metal t interface u andthe outlet'lull .above the slagmetalinterfaca as shown.:toicausedistribution f ofymolten metal directly into uthe slag.- The level the impeller 4| isfmadeadjustable"` a's re- 1 quiredby using anyuone of #several `different i lengths of extensions Extension;l (Il `may be l anua. 'rae-surreale can te made fromm 4round carbonlelectrode of suitable diameter',` for example l0 inches to 15 inches or moreifnecessary. The round electrode can be machined to form a rectangularV or other section 5I hav-t` ing one or more planesurface 54. For example. arectangle 5 inches wide and 10 inchest l5 `inches or -more in length" might be used.- The stirrer is immersed in the slag and metal. By'

its rotation a corresponding-rotary motionV of i 1 the contents of theladleis produced. 1

' )For betterpresults two or-more stirrers Illl and 4i* maybe used as shown in Figures 6 and 7. If two Vstirrers aroused, they should bespaced so that the clearance between therotating carbons should not be too great,` as for example. a clearance of approximately 6 inches to 1 8 mche l These Surfers mayfrtate in the same Y direction or inopposite directions. `If they `a`re rotated inthe same direction, the entiremasslof liquid contents of theladle willbe vgiven acorresponding rotating" 'motion as showny Jbyfthe arrowsinFigurefl. i i f A Where a plurality of stirrers are to beused as in Figures 6 and 7,` improvedresults` are obtained by having the stirrerseflectiveat'different levels in the bath. Thus inFigure 6` the Alstirrer 4i? extends deeper'into the bath than the stirrer I I; the latter stirrer operating chiefly v*in the 'slag and `not extendng'any great. depth below `the`^`slagmetal interface. These twostir` `r`ers`-produce a"'rlative movement betweeny the 519g andthemetal and also between respective Portionsof themetal. i

' In order to speed up the rate oflreactionuit vis i `desirable to' have a relative movementbetween theslaglayer and the metal. `'AIhe natural tendency would befor the `slas layer` and the metal` :layer to rotate together and thefrelativeumotion I.

sirable. Increased relative motion can be obtained by using the apparatus shown in Figures 8 and 9. A darn 55 is immersed in the slag layer and if desired, below the slag-metal interface 4I. Any desired number of dams may be used. The effect of the dam is to impede the rotation of the slag Whilst permitting a relatively unhampered rotation of the pig iron, thereby causing relative motion between the pig iron and the slag. The dam may if desired occupy the opening 21 when metal is notbeing charged, with suitable packings to exclude air.

Where there is considerable variation in the level of the pig iron, it is desirable to make the height of the dam adjustable s that the dam will always extend down to the slag-metal interface and also preferably slightly below the interface as shown. In Figures 10 and 11 I show a refractory dam 55' suitably of carbon refractory supported on a bracket 58 and adjustable as to height by an adjusting screw T threaded through the bracket and making thrust bearing connection with the dam 55'. To prevent the dam from rotating, a guide 5l extends from the darn through anopening in the bracket 58.

structures of Figures to 12 will be provided with a suitable gas-tight cover as shown in Figure 1.

To further promote better transfer of the impurities from the molten iron to the slag, the apparatus shown in Figures`l3 and 14 can be applied either alone or in conjunction with the dam 55 and/or the two stirrers 4I and Il* as shown. In this type of apparatus the refractory lining is constructed to form an inclined vane 82 extending around the ladle circumference from point 8l near the bottom to point 64 near the top and providing a vane shelf 65 which is a maximum at 63 and a minimum at 84. The vane 62 is capable. of converting some of the rotary motion of the liquid iron in the ladle into vertical motion, thereby bringing the metal from the bottom of the ladle upward to establish contact with the supernatant slag. The rotatory action `of the metal may be imparted by the stirrer; 4I;i and 4|4 or in other suitable ways.

Instead of usi-ng the mechanical agitators for producing o. rotary motion in the molten pig iron in the ladle, it is also possible to produce a rotary motion by means of electromagnetic action. By using polyphase alternating current to produce rotating magnetic fields in an iron core suitably n placed around the periphery of the ladle, preferably at or below the slag-metal interface, the.

current induced by the alternating electromagnetlc field in the molten metal contained in the ladle causes a rotary motion of the metal in the way that rotary motion is produced in a. polyphase induction motor.

Figures and 16 show such a polyphase stir,- ring ladle having a winding 66 intended for threephase alternating current, with phase field coils 81, 88 and 69 connected to a source at 10, I'I rand 12 and connected together at 13 (Figure 15).

`between the two would not be as great as de- Star connection is shown, but it will Abe evident that any suitable system of connections may be used. 'I'he winding is surrounded by an annular magnetic core 'i4 suitably slotted to receive the Winding as at 15 and desirably laminated. Low frequency alternating current at, for example, 25 to 100 cycles will preferably be used.

The device of Figures 15 and 16 will cause simultaneous rotation of both the slag and the metal. To secure differential movement between the slag and the metal, a slag dam 55 of any de-l sired type will desirably be used as shown in Figure 16; or an inclined vane 62 as also shown in this figure; or mechanical stirrers Will be ernployed as shown at H3 and l I4 in Figure 16, preferably causing the slag to rotate oppositely from the metal.

Figures 17 and 18 illustrate a variant electromagnetic stirring device. The desulphurizing vessel 20 is surrounded by a polyphase field winding 18 of Gramme ring type, wound on an annular magnetic core l1, suitably laminated, and provided with magnetic poles 18. In the speciflc construction, a three-phase winding consists of phase coils 19, 80, and 8| connected in delta formation to three-phase lines 82, titly and 84 from an alternating current source at commercial frequency. The magnetic core Il and the poles 18 will desirably be assembled from separate units, fastened together inany suitable manner.

The .Winding 15 and core 'Il are very desirably inclined or canted with respect to the horizontal as shown in Figure 18, so that in addition to a horizontal rotary or whirling motion in the iron, there will be a helical upward stirring component due to the inclination of the winding and core.

There will preferably be one coil and one pole for each phase, and, of course, the number of phases in the polyphase system may be varied. In general, the smaller the number of poles, the

'faster the stirring, other conditions being unsubstantial portion of the iron bath and not lmerely through the wall of the ladle. It is preferable, therefore, to use a small number of poles,

5 for example from two to six poles.

'I'he ladle of Figures 17 and 18 is desirably provided with a slag -darn 55 and with impellers H3 While the iron whirls in upward helical paths, the whirling of the slag is retarded by the dam 55. The impellers H3 and H4, which operate in the slag, will desirably rotate the slag oppositely from the rotation of the iron. For example, if the iron rotates in the direction of the arrow 85, the slag will preferably be rotated by the impellers in the opposite direction.

It will, of course, beunderstood that in Figures 15 to 18 the ladles will be provided with air tight closures.

Instead of a moving wave form of electromagnetic stirrer as shown in Figures 15 to 18, a poolsurrounding coreless induction form of any well known typemay be used. In Figure l an inductor coil BE' surrounds the upper portion of the metal bath adjacent the slag-metal interface. The neighboring structural parts of the ladle will desirably be made of non-magnetic metals or alloys or non-metallicematerials. A suitable alternating current of low frequency, for example 25 to 100 cycles, will be connected to the coil 66.

The coil will desirably carry a, high wattless currentdue to resonance obtained through suitably connected condensers as well known in the art.

v,`will.lso-me m m m dsirab-les isfcompaniedaby considerable wheatiobtained ativrelativelyzhigh Cossa v l i i helinductor` co stirringfis un- `The ladlesffor containing: the moltenmetaliand i slag to be rotated as describedabove.` should have atyertical axisofsymmetry about `whichthe.rotam tion takes place. For example; the interiorrcould be2-shaped inthekformfof afxcylinder` orinverted* ,truncated cone.` i The major` axis ofthe cylinder "OJCOIIIS, the

r cone stands `approximately verticallland''rotaon occurs aboutthisfaxis. It uislnotinecessary slag-metal interface as the lmetalfrotates about its natural axis. For example, the ovalcross section shownl` in^\.1'figure 419whenrotated by anyof "1 thetmeans described turns about an axis located at the point 85. An element Blof slag-metal in- An illustrative cycle of operations with refer# ence particularlyto Figure Y1 is;as follows: s The desulphurizing ladle is charged lthro"u`gh the l i opening `2'lwith the requiredamount of `de- `sulphurizing slag from the poi'l 88. This desulphurizing` slag may, for examplecompr`ise70 r per `cent of molten blast furnace slagpreviously withdrawn from the blast furnace, 20 per cent of l ."bur'ned limeand 10 percent fluorspar.` `'I'he blast furnace is tapped andaboutl'tons `of iron is transferred into `the ladle 1.29. As del scribed above, all siliceous contaminations should be removed from the `flowing streamioi ironby dams or skimming devices. 'I'he desulphurizing ladle and its charge is then closedagainst free. access of air Vor oxygen to the interior. `Desul-i` rphurizing is continued usingagitationluntil the proper sulphur content of the iron hasbeen ob-- hat the". cross sectionof theladleon1a"planefat.'A rightiangle to this axis of `syini'netrybe circular. `Indeedfit may ibe-"advantageousto user-some other.V y :shape as `for examplean ellipticalor ovalsection, thereby,facilitatingthelformation of new areas of 5000:'1` or more,` all conditions. if

onA may` berobtained from a `blast! fur- *nacel-productf containing"` initially as much as oaioeawroeoa, smpnuror more. 'rhesmphur l contentfof lthelslagsmay rise to 5% or 1062.

sulphur or more and al ratio'of sulphur in slag to f sulphur in theiron of 5 00:1"o1 1000:"1`fand even `denendingfup'on the chosen Y processes and apparatus `de scribed herein may be used for the removal of sulphur`frormolten"pigiironsupplied 4by fur- "1* nacesother than* a `blast furnace, as forexample ..a"cupola." `@Theuse forfsuch purposes is"ex` pressly-included' herein.1

` ,tions and modifications to meet individualwhim -1Inview`of the invention'and disclosurevaria- 'or particular needwill doubtless becmeevident fto others skilledin the art, to obtain all or ypart ofthe" benefits ofmy invention without copying the structure shown, and I, therefore, claim all such in soV far as they fall within the reasonable -spirit and scope of my invention.

Havingthus described my invention what claim-as new and desire to secure byLetters Patent is: m'

1. A desulphurizing vessel closed to the at- A`mosphere and providedwith a refractory lining adapted to `hold a charge of molten pig iron` and a body ofmolten desulphurizing slag on the iron,

electromagnetic means to induce electric cur.-

"rent within themetal as a secondary for imparting a generally horizontal rotary stirring to the .iron and means for rotating the slag in a direce tionopposite from that of the4 iron.

` 2. A vessel for desulphurizing molten metal whosemajor vessel axis is vertical having a refractory liningrand adapted to contain molten metal and desulphurizing slag on the molten l metal, walls forming a charging opening, a metal tap opening and a slag tap opening at a different level from the iron tap opening on a side oppotained. For best results vacuum may be ap- .plied to the ladle, as through a vacuum connecftion 89. 'i

` After the desulphurizing-reaction is completed. the slag is removed by tilting the ladle 2.0 `about the axis 90 andallowing the slag tofrun out the:

opening 8l (suitably closed against air contamination when not,in use) "into theV slag pot 88.v 'Ihereupontheladlel is tilted in the reverse 1 direction about the axisziand the` iron is poured through the tea-potspout"93(suitably sealed when not in use) into thetransfer ladlesgl. An axis is also provided at 92` for` pouringthe ensite to themetal tap opening. means for closing the openings against air contamination, means for tilting the vessel about an axis adjoining one tap opening for discharging'from that tap openthat tap opening. i

3. A vessel for desulphurlzing emetal, whose major axis is vertical, havingal refractory 1in# ing to receive molten metal andslag, means for lifting the metal from a level just below the slag and delivering it upon the surface of the slag, and

separate means for stirring the body of the metal. t

m 4, A vessel for desulphurizing metal whose major vessel axis is vertical, having a refractory lining to receive molten metal and slag, means for y circulating this` slag at upperlevel without circulating a substantial part of the molten metal and "tire ladle content, slag" and iron, in#emergency.v Two or more transfer ladlesifmay be4 used `if necessary and the stream of metal `i'roi'n the rcie-g4 smphunzmg ladle can-be interrupted by tilting i the` ladle 20 vwhilst a new `transfer ladle is brought into position;v -It isrimportarit thatany desulphurizing slag remainingin thetdesulphur'- izing ladle be kept from entering theY transfer `ladies 94. The inclined teapotspout S31is eiTective to preventthis. If further precautions are necessary the smalltea-potskimmer ladle can be placed just ahead of the transfer ladies v Withgood agitation and efficient slags. Va. pig

iron containing 0.015% sulphur or 0.010%` sulondary.

separate independent means for circulating the `molten metal at the` samemetal upper level at l which the slag is circulated, one of the means.. being electromagnetic` and operated by inducing electric current within the molten metal as a sec- 5. A vessel-fordesulphurizing molten iron having a vertical axis and adapted to hold molten iron` and slag noating upon the molten iron, a mechanical stirrer for the slag when the slag `reaches an upper level of the stirrer, stirring the slag independently of electromagnetic circulation of the iron and electromagnetic means for stirring the iron differently from the stirring' of the slag when the slag reaches said level.

G. A vessel for desulphuri'zing molten iron ing and means for tilting the vessel about an axis adjoining the other tap opening for pouring from i whose major axis is vertical, adapted to contain to stir the slag without stirring a substantial part molten iron and slag oating on the iron. a meof the body of the iron when slag is present bechanical circulating means vfor circulating lthe tween the levels of the two tap openings and elecslag without circulating a substantial part of the tromagnetic means i'or stirring the iron sepabody of the iron and electromagnetic means act- 5 rately from the stirring of the slag, acting by inling by inducing current within the iron as a secduction of current within the iron as a secondary.

ondary, located below the mechanical means, cir- 8. A vessel for desulphurizing molten metal culating the body of the iron as distinguished `whose major axis is vertical, having a refractory from the slag when the slag level is that within lining, a mechanical circulating device adapted to which the mechanical circulating means is l0 operate in the slag when the slag reaches an upadapted to operate. per level and a pool-surrounding coil located in 7. A vessel for desulphurizing molten iron havthe upper part of the vessel and below the meing a refractory lining adapted to contain the chanical circulating device, said pool surroundmolten metal and desulphurizing slag on the ing coil being adapted to induce electric current molten iron, wallsV forming a charging opening, 15 within the upper part of the molten metal rather an iron tap opening and on the side opposite to than in the slag when .the molten metal and slag the iron tap opening, a slag tapv opening, means reach the level at which the mechanical circulatfor tilting the vessel about axes adjoining the reing device is effective.

spective tap openings for discharge from these f tap openings, mechanical stirring means adapted go v RUSSELL PEARCE HEUER.

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