US89441A - Charles william siemens - Google Patents

Description

2 SheetsSheet l.

O. W. SIEMENS MBTALLURGIGAL'PROGESS AND FURNACE.

,441. Patented Apr.'27, 1869.

2 Sheets-Sheet O. W.=SIEMENS. METALLURGICAL PROCESS AND FURNACE.

No. 89,441, Patented Apr. 2'7, 1869.

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I mi W CHARLES WILLIAM SIEMENS, OF WESTMINSTER, ENGLAND.

Letters Patent No. 89,441, dated 411M727, 1869.

IMPROVEMENT IN METALLURGICAL PROCESSES AND FURNACES.

The Schedule referred to in these Letters Patent and making part of the lame as heretofore patented by me, are used for the produc-- tion-of cast-steel.

Cast-steel may be produced directly from the ore,

by the process described in the specification of certain.

Letters Patent granted to me, and bearing date September 20, 1866, and numbered 2,413 of British patents, or it maybe produced by meltingcast-iron (containing, by preference, manganese) and scrap-iron or scrap-steel, or blooms of puddled steel or iron, in a reverberatory furnace; "or it may be produced by these two processes conjointly.

In the specification to the before-mentioned Letters Patent, two furnaces were shown, in one of which the ore, with its admixtures of fluxes and reducing-agents,

descended at the two sides of the heated chamber, and in the other of which the ore descended, through a single shaft or hopper, upon the bed of the reverberatory furnaces.

According to my present improved furnace, these shafts or hoppers are placed vertically, or nearly so, and are made of considerable altitude, descending, at the same time, to the surface of the metallicbath in the furnace, or nearly so, in order to cause a more gradual and uniform descent of the ore into the furnace, with as little exposure as possible of the spongy metal, reduced in the hoppers, to the oxidizing-influence of the flame; and the reduction of the ore within these shafts or hoppers is further assisted by the application of fines or heated chambers around them, through which the heat of the furnace is made to circulate. 7

Into cach ivertical ore-shad, a pipe, carrying a supply of hydrocarbon, or other reducing-gases, may be made to enter from above, with its outlet near the base lie bath, of cast-iron, introduced through side doors of the furnace, which greatly facilitates the liquefaction of the metallic spongy iron formed in the hoppers.

With the ore, scrap-iron'or steel, such as engineers tnrnings, &c., or cast-iron in a more or-less divided state, maybe charged into the hoppers, to be also-abs'orbed in the metallic bath or wrought-metal may be fed in through separate side doors or hoppers.

If only wrought and cast-metal are to be employed, then, in place of the vertical hoppers or shafts, inclined hoppers may conveniently be adopted, through which the pieces of wrought-iron, such as bars or old rails, descend by gravity, dipping, with their most heated ends,into the metallic bath, where they are dissolved; a certain portion of the flame being allowed to escape out of the top of the hopper, in order to-warm the iron duringits descent, and withoutlowering the temperature of the furnace; or pigs of cast-metal, by preference white metal, may be fed down these hoppers, and an oxidizing-flame be resorted to for efi'ccting the necessary decarbnrization, the oxygen supplied by the regenerative-gas furnace to be employed being at a very elevated temperature, and therefore well "adapted for effecting such dccarburization, which, moreo er, may be aided by stirring, and by the addition of compaiatively pure metallic oxides on the surface of the bath.

At the end of each operation, whatever maybe the ingredients employed, before tapping the metal, I generally add a certainproportion of rich Spiegel e'isen, or of metallic manganese, to the bath, in order to im-. prove the quality of the steel.

The ore to be employed for the first-named process should, by preference, be a pure oxide of iron, containing as little gangne, or sulphur, or phosphorus, as possible. Magnetic-iron stone, hematite ore, and such calcined spathic ore, are particularly applicable; or such a mixture may be conveniently adopted as contains both silica and fluxing-materials, such as lime or magnesia in suitable proportion, avoiding the necessity of adding separate fiuxing-materials.

Having thus premised, I will now proceed more particularly to describe my invention;

Figures marked 1, 2, 3, 4-, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17 18, and 19, .of the accompanying drawing, show the betbre-described two principal types of furnace for the production of cast-steel in large masses, one of which is arranged more particularly for the employment of oxides; or other iron-ores, and the other for the conjoint employment of bars or rails of wroughtiron or steel and of pig-metal, or for the employment of pig-metal only.

Figs. 1 to 7 show my improved furnace for prodna cing steel directly from the orc.

Figure 1 is alongitudinal section through thefurn'ace and regcnerators, it being. taken on line 11 of fig. 5. Figure 2 denotes a transverse section on line 2-2 of fig. 5.

Figure 3 showsan elevation of the furnace, and also a section through the gas-passages, on line 3-3 of fig. 2.

Figure 4 represents an elevation of the tapping-hole side of the furnace.

Figure 5 shows a sectional plan on line 5-5 of fig. 1,-

and

Figures 6 and 7 show enlarged details or parts to be hereinafter explained.

Similar letters of reference indicate similar parts in each of-the figures.

. One or more gas-producers, such as described in the specifications of former Letters Patent granted to me,

are to be used with my present furnace, and, when used may be placed at a considerable distance from the urnace.

The gas is conveyed from the producers through the flue A, (see fig. 2,) and directed, through the passages of a reversing-valve, B, alternately into the regenerators 0 O, whence, after becoming heated, it passes into the furnace alternately at the right and left-hand side of the heated chamber I) thereof, at which points the gas meets the atmospheric air proceeding alternately from the regeneratdrs HE, and enters into combustion with the same.

The atmospheric air is directed into one or other of the regenerators E E by the reversing-valve B.

a is the flue through which the products of combustion escape to the chimney.

p I would remark that, in mentioning reveising valves, and regenerators, and gas-producers, I have reference to such as'are, in substance, described .and'represented' in Letters Patent, hos. 41,788 and 42,717, heretofore granted, in the United 'States of America, to me and Frederick Siemens In the first of such patents was shown, in connection with'a puddling-furnace and its 'dischargefiue, a system or series of air and gas-regenerators, having conduits and dampers, arranged so that air and gas could be led into'and through such regenerators and furnace, and out through the chimney.

The last-mentioned of such patents exhibitsa gasproducer designed to be used in .connection with the Dare to .be constructed of the most refractory materials, such as the best silica or Dynas brick, while the bottom or bed maybe formed ofa mixture of two descriptions of sand, the one being nearly pure silica, and practically iufusible, and the other a fine red'lpam, which, in being acted upon by the bent of the furnace near the surface, fuses, and thus binds the white sand togethcr, so as-to form a hard and impervious crust, for the reception of a bath of molten steel.

, A mixture of two or three parts of white sand with one of red is found to answer well; but it is important that the two sands shouldbe well mixed, and charged dry into the furnace or a natural sand may be substituted, if a suitable quality is to be obtained.

The surface of the sand is so formed as to constitutc 'the hollow bath shown in the drawings; and, in

order to give a certain thickness and solidityto the crust, I charge the last portions of the sand in their layers when the furnace is already at a full weldingheat.

' 1n the roofof the furnace 11.10'lbl'lll0l1 t\\'0,Qli'fllllfbl' orifices, through which the interior of the furnace comthe vapors and sulphurous acid, 850.

The gas may also be passed over quick-lime, to communicates with two. vertical cylindrical chambers, F F, (see figs. 1 and 2,) which are 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 clay.

The upper ends of the chambers I" are made to communicate with a chimney by means of pipes, H

H, provided with regulating-dampers, h h.

Through the open upper ends of these chambers,

two vertical hoppers, pipes, or retorts, I I, pass down be constructed of cast-iron, and may continue to slightly increase in diameter as they descend.

Thelower portions, 2', of such pipes I I are to be made of day, such as is usually employed for making steel-melting pots.

The clay cylinders '5 maybe attached to the iron pi'p'esi by means of bayonet-joints, as 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 section and plan of the iron cylinder.

These hoppers or retorts I I receive the ore with which the-furnace isto be charged.

' The requisite reducing-gases are to be conveyed into the mass of ore contained therein through small pipes, J J, descending through the hoppers.

The reducing-gases may be derived from the gasproducer or producers before alluded to, in which case they are to be forced, by-a steam-jet, into the lower part ofa scrubber, L, (see fig. 1,) which is to be filled with coke, or other suitable loose material, over which water is to be made to trickle in copious streams, such water escaping through an overflow, Z, the object being to wash and purify the gas, so as to remove therefrom plete the purification, and through a heating-apparatus, if thought desirable, before reaching a cast-iron cross-pipe, M, through the ascending pipe N, communicating therewith. From thence the gas descends through the pipes J J, as before described.

These pipes are carried by the cross-pipe M, being dropped through openings, (in the topof-the latterg) provided wit"! coversym m.

The pipes, provided with flanges at their upper ends, rest upon the inner bottomsm'face of the pipe M.

By this arrangement or application of the pipes J J to the pipe M, either of the pipesJ J'may be readily removed from the pipe M, and exchanged for a fresh one,'in case of being injured by the heat of the lower parts of the tippers.

The cross-pipe M can also be readily removed, and the hoppers themselves be raised, whenfinjury may occur to their lower parts of pot-clay, which are exposed to the heat of the furnace.

The bayonet joints between the clay and iron portions of the hoppers admit of the latter being readily separated fromthe furnace, and exchanged for others, in case of injury, one or more of them being generally kept in readiness in-an annealing-stove.

' The mode of working this furnace may be thus described: In heating the furnace, the open upper ends of the cylindrical chainbe sLE F are to be closed by covers, whioh'are to be replaced by the hoppers I I, when a full white heat has been obtained.

- As soon as the hoppers are in p1ace,a small charge of charcoal is to be introduced into each, which should be followed by the ore, or compound of ore and reducing-agent and flux to be employed, until they are en tirely filled.

the furnace to pass upjin-the annular spaces surround-' .ing the'hoppers I1 in'th'ebhambeis F F, in order to heat the hoppers to redness. At the sanie time, also,

pig-metal is to be introduced into the furnace through the side-openings O 0'. This metal, on melting, will 'form a bath of molten metal below the hoppers, and on the bed of the furnace.

By the conjoint action of the reducing-agents, and of the heat applied externally to the hoppers, the ore will be reduced to spongy iron, which, coming into contact with the metallic bath, will be readily absorbed and dissolved therein, the earthy constituents rising to the surface of the bath in the form of slag or scoria. V In proportion as the spongy iron produced by reduction'in the hoppers is dissolved, fresh material should be added t6 the .top of them, and it will gradually depcend in the hoppers, and, in its turn, will be reduced and dissolved.

- The heatof the furnace being maintained-at a steelmelting heat, it is 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 0) upon the sloping ,banks, whence the molten cast-metal descends into the bath, and supplies fresh carbon to the same.

The scoria which may form upon the surface of the metallicbathshould' be' removed, from time to time,

- through the opening P', which may be ata lower level than the side or charging-doors P, as indicated in the arrangement of this furnace at figs. 4, 15, 16, and 18.

When suificient molten metal has accumulated upon .the bath, disks of cast-iron, lined upon the under sides with clay, are tobe introduced'upon the surface 'of the ore in the hoppers.

These disks may be made in two parts, for the conven -ience of. introducing them without removing the gassupplyfpipes J J,.and the two.halves' 'may beunited by .a strong wire fastened through lugs, and forming a 100p.

When these disks-may havedescended' (by the weight of the orefilled in upon-them) until they have'passed the joint between thecast-iro'n and clay hoppers, wires connected to the disks may be caused to catch upon the. gas-pipe M, and prevent their further descent.

The'material below the disks having become absorbed in the bath, the latter should be stirred and tested. The slag should be of aliglt brown or alight green color, and contain little iron, in combination.

Should it be heavy, and dark in color, and the metal bath below it be thick and partially set in masses of malleable metal, more cast-iron should be charged in at the side doors or the hoppers O, and it will also be" advisable to'throw some charcoal upon the fluid bath.

The heat of the furnace must also be raised to and -maintained at a 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 suflicient flux; has not beencharged with the ore to combine with the silica generally contained in it Quicklime should be added, which will readily combine with the slag, and will liberate the iron, and allow the same to pass into the metallic bath below. I

' To assist'in the reduction of the iron contained in the slag, I often throw in, after adding the quick-lime, about ten pounds of charcoal, and stir it wellinto the slag, so regulating the flame, at the same time, that there is a slight excess of gas in the furnace, in order not to burn the charcoal away too rapidly.

saw

Should much slag remain, it should, by means of a lake, be removed through the centre door, P, the sillplate of whi h is to be arranged nearly on a level with' This sample of metal may be plunged into water while it is red hot, after which it may be broken under a hammer, and touched with a ,file. Should it break toughly, and should the file touch or abr'ade it freely, such is proof that the metal. contains but 0.1 to 0.2 per cent. of carbon,-and is in' the required condition; but, on the contrary, should it break short, or be found Loo. hard: to yield freely to the file, it will be necessary,

to stir the bath under the influence of an oxidizingflame, (by reducing the supply of gas? or to reduce the proportion of carbon, by addition 0' scrap-iron or scrap-steel, of mild quality, or of oxidizing-agenm,

such as rusty iron-tumings orbon'ngs, iron-ore, by-

preferenc'e, magnetic-iron sand, containing titanic acid, nitrate of soda, litharge, or red lead, at, stirring the bath at the same time, toexpose all parts of themetal freely to the' action of thereagents added, until the proper condition may be obtained.

This having been eflected, from five to eight per cent. of ferro-manganese or Sptegel ciscn is-tobev charged in on the bridges of the furnace, through the side doors, and the furnace is to -be.'woi ked with a slight excess 'of gas, to prevent the oxidation of the Spiegel 6am, and with an outward ;pressure-at the doors; or the Spiegel eiscn may be melted in a separate furnace, either in crucibles or on an open bed, and charged into the principal furnace in a liquid state.

The bath should be stirred gently as soon as the Spiegel eiscn is melted, afier which,wh'en the metal has ceased to boil violently, it may be considered; as ready for being tapped: p

The precise amount of Spi'egel eisen to beadded 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 the ore employed is very pure, no Spiegcl eism may be required.

Samples may be and when the required temperha's been reached, the

steel may betapped. at once intothe ladle; but in" most cases, where the ore is not'exceptioually pure,- and the steel obtained from it is contaminated with asensible amount of sulphur, phosphorus, or otherim-'" purities, it will, be found that ingots, castfro m the steel without the addition of Spiegel e'iscn; ferro-manganese,0r other reagents, at. the end of the process are red short, and cannot beforged, and the greater the impurity of the steel, the larger is the amount of Sjiicjd cisen that will generally be required.

To admit of adding suflicient proportion of manganose, in the form of Spicgcl eisen or ferro-manganese, in which form alone it is generally obtained, without, at the same time, introducing so. much carbon as to makethe steel too hardfor many purposes, it is advisable, in most cases, to decarburet the metal almost entirely, before the Spicgel eism is added; and this plan of reducing the proportion of carbon, in the first instance, to a definite point, and. adding a fixed percentage of Spiegel cisen, has the further advantage of facilitating very much the production of a uniform temper of steel.

By a little practice, the point at which the metal is sufliciently decarburized may be judged of reryaccurately by the appearance of the fracture of the sample taken out.

taken out ofthe bath at intervals,

"In the above-described process, before putting in' the Spiegel cisen; I frequently throw into the bath a posed, the oxygen attacking the. remaining carbon, as

well as the silicon, while the metallic lead, liberated,

combines with any sulphur that may be present, and thus powerfully contributes to prevent red-shortness of the steel produced.

'I prefer to employ the litharge in fused pieces, or to form it (or any other oxide of lead) into blocks before use, by adding it, previously heated, to fused nitrate of soda, nitrate of potash, or other fused salt, (to which I sometimes add peroxide of manganese, either with or without other reagents) as long as the litharge added continuesto be thoroughly wet by the salt, and by casting or pressing the mass into suitable pieces.v

Thesesolid blocks sink more readily in the metal, and if an oxidizing-salt is used to cement the litharge together, it will also .aid in oxidizing" the remaining carbon and silicon, andin improving the quality of the steel.

to the charge depends on the amount of impurity in the steel; but I-tind that from three to eightper cent. is the proportion generally required.

Other salts, such as the tn'ngstates and mangauates of soda, or the-metallic acids by themselves, may be used forproducing similar effects.

When the litharge is thrown in, to prevent the .vapors thereof from getting into the regenerators, where they would, intime, tend to fuse the heated brickwork, I, by preference, shutoff the. communication to the chimney, and open a communication leading from the back of the furnace into the open air,-or through a suitable connection, lined with fire-hrick,'into acoudenser, communicating, at its further end, I with a chimney or otherexhausting-apparatus.

I construct the condenser, by preference, of a series of vertical or inclined iron tubes, through whichwater is madeto circulate.

The litharge-condensed upon the tubes may be removed from time to time, andused again for the same purpose.

lhe ladle T, shown in section at fig. 16,. (which represents a modification of the steel-melting furnace,) is mounted upon wheels, and lined in the usual manner, and heated internally by means of a gas-flame or When the charge is ready for being tapped, it may be moved in -front of the furnace and below the u ping-hole S.

The loose sand is next to be removed frorn the tapping-hole, and put on one side, until a portionof the hard crust, in contact'with the bath of metal, is exposed. Thereupon, the crust should be pierced (by a pointed iron bar) at the lowest point, andthe metal will run into the ladle;

The ladle should next be movedv upon the rails, to 1 and over a casting-pit, provided with mouldsxof a suitable form and size 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 ingots thus obtained are to be hammered and rolled in the usual manner, or the metal may be cast The amount of oxide of lead that should be added made up in the usual manner, with sand or loam, the wires holding the disks should be cut, in order that they may be forced down (by the ore in the hoppers) on the bed of the furnace, and a fresh charge of ore be made to descend, as before.

It is, however, not in every case necessary to introcase the action of the hopper-will be strictly continuous.

The clay hoppers 1" may be dispensed with by making the cast-iron hopperst' continuous, and supplying in themselves the cast-iron requisiteto form the metallic absorbing-bath,

This arrangement is shown at figs. 10 and 11,

Figure 10 being a longitudinal section, and

Figure 11, a transverse section of the furnace, which, in this case, is provided with only one iron hopper. I I are the cast-iron tubes, or cylinders, connected together by means of bayonet-joints, as shown attire enlarged sections and plans, at Figures 12, 13, and 14, which tubes are filled with the ore, and are passed down the chambers F to the bed of the furnace -D, where they are melted down with the ore, as described.

nace, fresh ones are tobe attached at the top,- from the platform G.

The upper part of the chamber 13 ,does not, in this case, communicate with a chimney, as in the previous arrangement, theascending gases, through the same, escapinginto the atmosphere around the descending hopper.

The other parts of the furnace, and the mode of operating with the same, are the same as described with reference to the previous arrangement, and need not beagain referred to.

Figs. 15, 16, 17, 18, and- 19, of thedrawings, show cation. of my improvement. this mode or'furnace, cast-steel may be prepared from a mixture of bar-iron, or old rails of wroughtiron or steel, and pig-metal, alone.

Figure 15 denotes a longitudinal section of the furnace, on 1ine'15-15 of fig. 19.

Figure 16 denotes a transverse section, on line 16 16 of fig. 15. I

Figure 17 represents a rear elevation, and

Figure 18, a front elevation of it.

Figure 19 exhibits a sectional plan, taken on line 1949 Qrfl 15. r

In this arrangement or form of my invention, sloping hoppers -I are substituted for the vertical hoppers in the previous arrangements.

Down these sloping hoppers, bar-irou or old rails may be slid from the platform G, so as to rest withtheir ends upon the bed of the furnace. I

Pig-metal, at the same time, is to be introduced through the side openings O,so as, in melting, to form a bath, in which the bar-iron or rails dissolve.

v As the latter are thus made gradually to slide down the hopper I, a portion of the highly-heated products of combustion from the furnace is allowed to pass up the hoppers, escaping. at the open ends thereof, after having-heated the wrought-iron to arcd heat, preparatorty. to it passing down into the bath.

If cast-iron aloneis employed; white pig-metal should .be used, which is to be introduced into the furnace in a'similar manner to the bar-iron, that is to say, down the hopperI. In this case, the gas supplied to thefurnace would be relatively diminished, and the chimney-dranght increased, causing a current'of intensely-heated oxygen to pass over the metal, and to effect its decarburizationl throwing in fresh sand, and the tapping-hole nas been duce the disks at the end of every charge, in which As the tubes melt away and descend into the fur another modification of my improved furnace, or another mode in which ;I have contemplated the appli- This efiect may be increasedmy occasionally atirring the bath, and also by the introduction, upon the surface of the bath, of oxides of iron, by preference, of magnetic sands containing titanic acid, which latter will become absorbed, and improve the quality of the ste'el produced.

A sufficient quantity of metal having accumulated in the bath, and the proper chemical condition of the bath having been ascertained, by taking out a sample, and regulated, as before described, from four to eight per cent. of Spiegel eisen may be introduced, through the side doors P orthe hopper O, with or without the previous addition of a certain proportion of 'litharge or other oxidizing-salts, as before described; and the process of tapping may be carried out in a similar manner to that described with reference to the first arrangement.

Having thus described the nature of my invention, and the best means I am acquainted with of performing the same,

I wish to be understood that what I claim, is-

1. Treating the metal in the bath of thefnrnace with litliarge, or any other oxide of lead, formed into .eakes or compact masses before use, by mixing it, substantially as described, with fused nitrate of soda, nitrate of potash, orany other fused salt, to which I sometimes add an oxide of manganese or other re-' agents.

2. The method of preventing injury to the furnace, or the choking up of the regenerators or flues, when oxide of lead,'or other substances, which give off gases or vapors, are added to the molten metal in the bath of the furnace, by drawing off the gases or vapors, or the greatest part of them, from the furnace, without letting them pass into the regenerators or flues, and condensing them, to recover the products.

3. The combination and arrangement of one or more tubular hoppersI I, and the surrounding heating-chamber or chambers F, with the furnace D, whether such hoppers be either wholly of metal, as

shown in figs. 10 or 11, or constructed partly of metal 6. The combination of the system of heat-gem' erators, as described, with the furnace D, its tubular hopper or hoppers, and the air-heating chamber or chambers thereof, the whole being to operate together, and with one or more gas-producers, appliedsubstantially as described.

7. In connection .with the process of making steel by a bath of metal, and one or more hoppers and heating-chambers thereof, as described, the employment of a series of regenerators, (of the kind described,) in such manner that a portion of the products of combustion shall be withdrawn to heat the ore, metal, or materials, while descending, through the hopper or hoppers, into the furnace or. bath-chamber, and the remaining products of combustion not reduced in temperature, be caused to pass through the regenerators to, and escape by the chimney, the effect being to not-- reduce the temperature of the furnace by the introduction of the cool ore or materials through the hopper or hoppers.

o. W. SIEMENS. Witnesses:

ROBT. Lmxson, EDWD lfl. HoBBs.

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