US95843A - Improvement in the manufacture of iron and steel - Google Patents

Description

` ment of 'oxides or other iron ing steel directly from the ore.

stone, hematiteore, and rich calcincd spathie ore, are particularly applicable, or such a mixtureniay be conveniently adopted, as contains both silica and fluxing material, such as lime or magnesia, in suitable proportion, avoidling tho necessity'of adding separate uxiug materials. Having thus premised-,I will 'now-proceed more particularly to vdescribe my invention.

Figures marked l, 2, 3, 4,' 5, 6, 7, 10,11, 12,

.l 13, 14,15, 1,6, 17, 18, and 19 of the accompany? ing drawings show the betbre-described'two principalt'ypes of furnace'for, the 'production' of cast-steel inlarge masses, one of which is arranged more particularly for. the employores, and the other for the conjointl employment of bars or 'rails of wrought-iron or steel, and of pig-metal,-

ofthe furnace. Fig. 5 shows a sectional plan on line 5 5 of Fig. l; and Figs. 6 and 7 show enlarged details or parts, to be hereinafter ex.

plained. y p .s- Simlar lettersof reference .indicate simillar parts in each 0f the figures.

One or more gas producers, such as. described in the specifications of former Letters Patient granted to me, are to be used with my present furnace, and, when used, may be placed at a considerable distance from the furnace. vThe gas isconveyed from the producers through the due A, (see Fig. 2,) and directed through -the passages of a reversing-valve, B, altermately into` the regenerators c c, whence, after becoming heated, it passes intothe furnaceal-V ternately at the right and left hand side of the heated' chamber -D thereof, at which points y the gas meets the atmospheric air, proceeding alternately from the regenerators E E, andenters into combustion with the same. The atmospheric air is directed into one or other of the regenerators E E by the reifersing-Valve B. A is the due, through which 'the product-s of combustion escape to the chimney.

`I would remark that in nientioning'reversing-valves and regenerators and gas-producers, 'I have reference to such as are in substance described and represented' in-'Letters Patent Nos 41,788 and 42,717, heretofore granted, in the United States of America, to nie and Frtdericl/z` Siemens. In the irst'of su'ch patents was shown, in connection with a paddling-furnace and its'discharge-ue, a system or series of air and gas regenerators having conduits and dampers arranged so that all' and gas could bc led into aiid'through such rcgcncrntors and furnace, and out through the clay.

chimney. The last-mentioned of such patents exhibits a gas-producer designed to be used iu connection with the regenerator-furnace, as mentioned. t.

It will not be necessary, therefore, for me' to'herein enter into afparticular description otsuch regenerators and gas-producers, and their` general application to a furnace for the treatment of iron,for converting the same into steel, such being either in whole orin part represented in thev accompanying drawings, which- .also exhibit my present invention or improvements conneetedwith such a furnace-D, provided with such a system of regenerators, and

some, if not all,`of their conduits .or valves;

The root and sides of the said chamber or furnace D are to be constructed of the most refractory materials, such as best silica or Dynas' brick, while the bottom or bedmay be formed lof amixture of two descriptions of sand, the oney being nearly pure silica.prac

tically infusible, and the other aline red loam, which, in being acted upon' by the-heat. of thfe furnace near the surface, fuses, and thus binds the white sand together,-so as to form a hard `and imperviouscrust for the reception Lof'a bathpf molten steel. Amixture of two'or three parts of white sand with one of red isfound to answer well; but it is-importantfthat Kthe' two sands should be well mixed, and

charged dry into the'furnace; orajnat'ural sand may be substituted, if a suitable quality is to be obtained. The surfaeeof the-sanda so formed as to4 constitute the' hollow :bath shown in' the drawings; and in order togive a certain thickness and solidity to them-ust,

I-charge the last portions of sandin thin layers when the furnace is already at afull welding-heat. Inthe roof of the furnace are formed ytwo circular orifices, through which the interior of the furnace communicates with two vertical cylindrical chambers, F F', (s ee Figs. land 2,)l which a-re constructed of shells or tubes of wrought-iron lined-With brick-work, and are' suspended from the upper flooring or stage G, in 'order not to press upon the heated arch of the furnace. The joints between the arch and these. chambers-should be made good, with 'lhe upper ends of the chambers F F 4 are made to` communicate with achimney by meansof pipes H H', provided with regulating-dampersh h. Through the openV upper ,ends of these chambers two vertical hoppers, pipes, or retorts, I I', pass down nearlyto' -the surface ofthe bed of .the furnace D,'as

shown, they being suspended from the 'tops of' the chambers F F', The upper portions i of the upper pipes I II4 are to be constructed" ofcast-iron, and may continue to slightly in# crease in diameter as they descend. The lower portions 91' ofsuch pipes I l are to bemade of clay, such as is usually employed-for making steel-melting pots.

The clay cylinders i may be attached to the iron pipes z' by means of bayonet-joints, as

of the hoppers.

n`eenling-stove.`

1 The mode of working this iu'rnace may be` thus described: In heatingthe'furnace, tllej open upper ends of thccylindrical chambers shown at the enlarged details in.Figs."6 and 7, of which Fig. 6 shows a section and plan of. the clay cylinder, and Fig..7- exhibits a sec- '.'tion and plan of the iron cylinder. Thi's'combinat-ion of the furnace, tubular hoppers, and surrounding.heating-chambers,

" as well as the combination of a system otfheat, regenerators and gas-producers with the furnace-:its tubular hoppers, and airheating chamber or chambers, although described in `order to illustrate more fully the nature of my present invention, are noth'erein claimed, the same being the 'subject-matter, in part, ofanthe tubes J J and ofthe crossfpipe M ,presently referred to. f

v'lhesehoppers or retorts I I' receive the -ore with-.which the furnace is to be charged. The requisite reducinggases are `to be conveyed intothe mass of ore contained therein through small .pipes J J-, descending throughthe hop# pers.- AThe. reducing gases may bederived from the' gas producer or. producers before-alluded to, in which case .they are to be"forced Y bye steam-jet into the lower part of' a scrubyherL, (seeFig. 1,) which is to be filled with 'coke or other suitable loose material, over which water is to be .made to trickle in; continuous streams, such water escaping through an' overflow, l, theobject being to wash vand'purify the gas, so as to remove therefrom thefvapors and sulphurous acid, &c. Thegas may also be passed vover quicklime, to complete the purification, and through a heating .appav ratas, if thought desirable, before reaching a cast-iron crosslpipe, M, through the ascending pipe N, communicating therewith. From thence thegas descends through the pipes J J', as before described. lh'ese pipes are can-` riedi by -the cross pipe M, being dropped through Aopenings (in the top of the' latter) pro- I vided with covers m m.- The pipes provided with flanges at their upper endsrest upon the inner bottom -surface of the pipe By this arrangement or application lof 4the pipes J J tothe pipe M, either 'of the pipes J 'J' may be readily removed from the pipe M,

Y and Vexchanged for a fresh 'one in casev of beinginjured` by the heat of the lower parts The cross-pipe Mcan alsol be readilyremoved, and the'hoppers themselves be raised when injury may occur to their lower 'parts -of pot-clay, Which'are ex- .posedto the heat ofthe furnace, The bayonet-joint between the clayand. iron portions ofthe hoppers admitsofthe latter being readily separated from the furnace andaexchangedior othens in case ot' injury, one or more of them being lgenerallykept-in readiness in anan- F F are to be closed by covers, which are to `be replaced by the hoppers I I when a full White heat has been obtained.- As soon as the `hoppersare in .place asmall charge of char coal ,is to be introduced into each, whichshould b e followed by the ore'or compound of ore, and vreducing agent and fluir, to be'employed, until they are entirely filled. The gas supply-pipes'J J having likewise been placed 1in position, a supply of reducing-gas is to be lnext turned on, which can be regulated according to circumstances 'by means of the steainfjet usually employed in forcing it on.

The dampers `li h of the tlues H H are also.

to' be opened. in Vorder to cause aportiou of the flame from the furnace to pass up in the annular spacessurroundingthe hoppers I I in the chambers F F', in' order to heat the hoppers ,to redness. At -the same time, also, pig

vmetal is to b e introduced into the furnacethroughv the side openings O 0'; This metal in melting :will form a bath of molten metal `'below-the hoppers and on the-bed ofthe furnace.' By the conjoint action ofthe reducing agents and of the heat applied externally to the hoppers, the ore will be reduced tospongy iron,-which, coming into contact with-the metallic bath, will be; readily absorbed and dissolved therein, the earthy constituents ris-` ing to the surface of. the bat-h in the form ot'- slagor scoria'. In proportion as the spongy iron produced by reductionl in the hoppers is dissolved, fresh -material should. beadded to the top of them, audit will graduallydescend 'in the hoppers, and inits turn will' be reduced and dissolved.

The .heat oi'- the .furnace being maintained 'at a .steel-melting heat, itis necessary to observe-from time to time whether. the metallic bath'remains fluid. Should it commence to thicken, additional cast-iron is to `be introduced at the, side openings vO upon the sloping banks, whence the molten cast metal descends into the bath", and supplies vfresh carbon to the same.` The'scoria which may form upon the surface of the metallic bath 'should be re- Amoved trom time to time through the opening' P-, url1ich may be a'ta lower level than the side or charging doors P, as indicated in the -arrangen'ient of this f 'urn'ace at Figs. 4, 15, '16, and -18.V When sufficient molten metal has accumulated upon the bath, disks of cast-iron lined upon their under sides with clay are to be introduced upon the surface of theore in the hoppers. These disks may be made in -two' parts for the convenience of introducing them without removing the gas-supply pipes J J, and the' t\vo lialves maybe united by a strong wire' fastened through lugs and form- When these disks may have dei ing a loop. -scended by the weight ofthe ore filled in upon them until they have passed the joint between the cast-iron' and clay hoppers, wires connected tothe disks may'be caused to catch upon the gas-pipe M, and prevent their further descent.

'.lhe material below the disks having become i coal away .too rapidly.

little iron in combination. rShould it be heavy and dark in color and the metal bath below it' 'be thick and partially set in masses of mallea! ble metal, more-cast-iron should be chargf'ad` in at the side doors or the /hoppers 0and it will also be advisable to throw some charcoal upon the fluid-bath.v The heat of the furnace must also be raised to, and maintainedana full steel-melting heat, and the bath be stirred as soon as the pig-metal may be melted. Should the slag remain dark it is a proof that sncient flux has not been charged with the ore.

To combine with the silica generally contained in itqnicklime should be added, whichwill readily combine'with vthel slag, and will liberate the iron, and allow the same to passinto the metallic bath below. To assist in the re-v4 duction of the iron contained in the slagIv often throw in, after adding l the quicklime, about ten pounds of charcoal and stir it well into the slagso regulating the flame at the same time-that there is a slight excess of gas in the furnace in order not to burn the char- Should much slag remain it should, by means of a rake-be removed through the center -door P', the sillplate of which is to be arranged nearly on a level-with the metallic bath when full. 0r the slag may be allowed to run oilc continuously through ahoie or door, 'the height of which may be gradually raised by the addition of clay or sand, or otherwise, as the metal accumulates inthe bath. A sample of thel metallic bath may `next`be taken out by means ofa small ladle,

washed previously with plumbago.-

This sampl'eof metal maybe plunged into water while it is red-hot, after which. itv maybe broken 'under a hammer, 'and touched with a tile. Should it break" toughly, and should the tile touch or abrade it freeisuch is proof that the metalcontains but one-tenth to two tenths per cent. of carbon, andv is -in the required condition; but, on the contrary, should it break short or be found too hard. to yield freely to `'the tile, it will be-neces'saryto stir the bath under the iniluencelot' an oxidizingllame, by reducing the supply of gas, orv to rednce'the proportion of carbon by addition of scrap-iron or scrap-steel of -mild quality, or of oxidizing agentssuch as rusty iron turnings or boi-ings, iron orc by preference, magnetic iron'sand, containing titanic acid, nitrate of soda', 'litharge or red' lead, Srastir-` ring the bath 'at the same time to expose all parts ot the metal freely to the action of the reagents added until the proper condition may be obtained. iveto eight per cent of ferro-manganese 0rspiegelei'senis to be charged in on the bridges of the furnace through the side doors', and the 'llhis having been effected, from doors, or the spiegeleisen may -be melted' in a separate furnace, either in crucibles-or on an open bed, and charged into the principal furnace ina liquid state. v

The bath should be stirred gentlyas soon as" the spiegeleisen is melted, after which, when .the metal has ceased to boil violently, it may considered as ready for being tapped. The.' pre-l cise amount of spiegeleisen to be added will depend upon the-proportion of carbon remaining already in the metal, and on the `temper or the percentage of carbon required in the finished steel. '-If thel ore employed is .very pure, no spiegeleisen maybe required. .Samples may betaken' out of the bathat intervals, and, when therequired temper has been reached, the steel may be tapped at once into the ladle; vbut in mostcases where the oreis not exceptionally pure, andthe steel obtained from it is contaminated with arsensible'amount of sulphur, phosphorus, or other impurities, it will be found that ingots cast from the steel Without the addition of spiegeleise'n,` ferromanganese, or other reagents at the end of the process are redshort, and'cannot be tbrged,'and the greater the impurity of the `steel the larger. is the amount of spiegeleiscn .that will generally bel-required.

'lo admit of' adding-suiicient proportion of manganese in the -form of spiegeleisen, or

:ferro-manganese, in which formalone lit is gen-y erally obtainable, 'witholxt at the same time introducing so muchjcarbon as' to make the steel vtoo hard for many purposes, it is'dvisable, iii-most cases, to dcarbu'ret Vthe metal almost entirely before the spiegeleisen 4is added;- and this plan tof redncingthe proportion ot' carbon in the'tlrst-Finstalxce to a .delle nite point, and adding :a lined,v percentage of spiegeleisen, has. the Yfurtheradantage of.

facilitating very much the production-cf a uniform temper of steel. -By` a little-practice',

` the point at which the metal is vslufti'l'eiently dc- -carburized may be judged of very accurately 4by the appearance ot' the 'fracture-of'thesampletake'n out. 1

In the above-describedprocess', before putting `in`V the 'spiegeleisem I frequently throw into `the bath-a small proportionfofoxide of lead, by preference litharge, which; in sinking to the b'ottolnof theba'th by `virtue of its superior specific gravity, is decomposed, 4the city-v gen attacking the remaining-carbon, aswell as the silicon, while the metallicflea-d liberated lcombines 'with anyLsulphur that may bepresent,and 'thus powerfully contributes to prel venting red shortness of the steel produced.

The amount of oxide of lead that should he added to the charge depends on the amount of impurity in the steel, but I nd that from4 three to eight per cent. is the proportion gen-` erally required. Other salts, such `as the tungstates an'dluanganates of so'd-a, or the metallic acids by themselves, may be used for producin"` siluilar-eects. y y The l le T, shownuin section at Fig. 16,--

l:metal is exposed.

will bestrictly continuous.

melting furnace,) is mounted upon' wheels,

l and lined in :the usual manner,'and heated in ternally by means of a gas-flame or a cokeire. Then the' charge is ready for being tapped, it may be moved in front of the fur nace, and below the tapping-hole 'S'. -The loose sand is next to be removed from the tapping-hole, and lput on one side until a portion of the hard crust in contact with the bath of point. and the metal will run into the ladle. The ladle should next be moved uponthe rails to and over a casting-pit provided with molds of a suitable form andsize for the work required, each of which may be filled, one after the other, by raising the stopper U of the ladle by means of a lever.

The vingots thus obtained are tobe hammei'ed and rolled in the usual manner, or the metal may b e cast direct into dry'claymolds of the form in which itv is required for very- .I strongcastings. In this latter case, the amount of carebon .should be increased to one per cent. or more., The'quality or' steel so produced,

lmay be further modified by adding titanic they maybe forced down, by the ore in the hoppers, on the bed of thefurnaee, and a fresh.

charge of ore be made to descend, as before, v It.is,'however, not in every case necessary to introducelthe disks at the end of every charge, in which case the action ofthe hopperl The clay hoppers i( may be dispensed with by making the cast-iron hoppers i continuous, and supplying in themselves 'the cast-iron requisite to form the metallic absorbing-bath.

f This arrangement is shown at Figs. 10 and 11,

Fig. 10 being a longitudinal section, and Fig.'l

' scribed. .As the tubes melt away and descend into the furnace, fresh ones are to be-attached at thc top from 'the platform G. rI he upper part of'. the chamber F does not, in thiscase, communicate with a chimney, as in the previens' arrangement, the' ascending 'gases thronghsthe same escaping v.into the atmosphere around the descending hopper.Y

The other. parts vof the furnace, and the mode Th ereupon the crust should be pierced .by a'pointed iron bar at'the lowest of operating with the same, are the same as described with reference to the previous arl l rangement, and need not be again referred to.

rigs. 15, 16, 1718, ma 190iuw drawings show another modification of my improved furnace,or another mode in which I have contemplated the application ot' my improvement.. By this mode or furnace cast-steel may be prepared from a mixture of bar-iron, or old rails of wrought-iron or steel, and pig .metal alone. Fig. 15 denotes a longitudinal section of the furnace on line 15 15 of Figf19. Fig. 16 exhibits a tranverse section on line 16 16 of Fig. 15. Fig. 17 represents a rear elevation, and "Fig. 1S a front elevation, of it. l Fig. 19 exhibits a sectional plan, taken on line 19 19 of Fig. 15. v

. 1n this arrangementor form of my invcn tion sloping hoppers I are substituted for the vertical hoppers in the previousarrangements.

Down these sloping hoppers bar-'iron or old rails may be slid from vthe platform G, so as furnace.

in melting, to'form aybath in which the bariron or rails dissolve. As the latter are thus made gradually to slide down the hopper' I a portion ofthe highly-heated products of combastion from the furnace -is allowed to pass up the hoppers, escaping at the open ends thereof, after having heatedthe wroughtiron to a red heat, preparatoryto its'passing down into the bath.

So far, however,as concerns lthis mode of withdrawing a portion of the products' of combustion to heat the material descending through the hopper, I here make no claim to it,thc' same being described and claimed in the application for Letters Patent filed by me o'n the 13th ofM'arch, 1869. Y l' Ifcast-iron alone is employed White 'pig-metal should be used, which is to be introduced i'nto the furnaceiu a similar manner to the bar-A iron-'that is to say, down the hopper I, In

this case the gas supplied -to thefuruace Would i be relatively diminished, andthe chi m ney-draft increased,causin g la current ofintensely-heated' oxygen to pass over the metal, and effect its def carburizatio'n. This eifectmay be'increased by occasionally stirring'thehath,audalso by thein-l l troduction upon the surface of the bath' of oxides ofiron-by preference, of magnetic sands,co'n9 'taining titanic acid-which latter will' become steel produced. Y A sufficient quantity of metalhaving accumulated in the bath, and the proper chemical absorbed, and improve the quality of the` fore described, from-four to eight percent. of

spiegeleisenmay be 4introduced .through the side doors P, or the hopper 0, with or without the previous addition of-a cer-tain proportion of lith'argo-or otheroxidizingsalts, asl before described, and the -process of tapping to rest with their 4ends upon the bed ot' the ig metal at the. same time is to be .introduced/through the side openings o, so as, l

v may be carried out in a similar manner to that described with referencel tothe first arrange-v ment. I i

' Having thus describedv thenature of myin-v vention, and the best; means I am acquainted Y with of performing the same, I Wish to be unf such process beiugby eectin g simultaneous ly the reduction ofy iron ores in oneor more heated'hoppers, and the solution of the re-v 1 duced metal (without exposing it to the flame) ina bath ofmetal provided in the furnace,

substantiallyas hereinbefore described.

2. The mode vof* making 'cast-steel. upon the open hearth of a furnace, the same consisting m causing wrought-iron,-steel, or White castironl to descend upon@ inclined planes or through .hoppers, (where the metal becomes gradually hea ted,) and into a fiuidbath of casi:` iron under the inuence of very intense heat,

the metal being dissolved in` such bath, and

.converted into castfsbeel, substantially as de-k scribed. i y

3,. The-employment of a regenerative .gas-

-unace'with a bath of metal, and one or more hoppers used, as described, during and by the process of .makin g. steel thereby, as explained.

' ,-0. W, SIEMENS.

-W'itanesses:

ROBT. LINKsoN, EDWD.- N. HOBBS, A

Both of ZPpes Head Alley, x y omhll, London, Gents. y

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