US RE3036 E
Description (OCR text may contain errors)
UNITED STATES PATENT OFFICE- IMPROVEMENT IN REFINING IRON.
Specification forming part of Iwih-rs Patent No. 1-],25Tlda1ed l"ehruar 1'2, 185G; Rvissuc No. 1,686, dated To (4Z5 whom, it may (O/M'fil'ib.
Be it known that l, Uums'rmx Snoxu, for mcrly 01' Youngstown, ()hio bui now residing in Ihila 'lelphia in the State of Pennsylvania, have diseowiared and invented a new and use ful improvement in the munuliwture, relining, and deearbonizing or partially decar bonizing molten crude pig iron bythe employment and application of an air-blast forced into themolten metal, which has theel'l'cetol're lining and deearbonizing the same in a greater or lesser degree, depending upon the time the blast is continued, and preparing it to be molded into ingots or other forms of iron or steel fit for the hannner or the rolls; or the said refined metal can be molded at once into castings, where strength. is required over com mon castiron. This refined metal is equal to malleable bar-iron'to use in the crucible process for the nmnufaeture of fine east-steel, and can be taken in a molten. state direct into the crucibles for this purpose; or it can be employed in a cold state, to be reconverted into fine cast-steel in crucibles.
In this process I use a compound consisting of common salt and manganese, which may be of various proportions, though I prefer about equal parts of each. This compound has the effect of a flux and detergent in removing the sulphur and other impurities contained in the crude metal. It also improves the quality of the iron, as hereinafter shown. It can be employed in the manufacture of the crude metal, or it can be added to the same when afterward remelted. From one to two per cent. of the flux at a time is sufficient. 1t may be that attemptshave been made to use one or the other ofsaid ingredientsin some form in the manufacture of iron, but never, to my knowl. edge, with any practical results anterior to my application for the same in the year 185-1. \Vhen the refined metal is intended to be molded into castings, the carbon is less redueed than when it is to-be wrought under the hammer. The metal therebyremains fluid a longer time while being" poured into the molds.
This application is groimded on my application and papers iiled in the Patent Office on the 28th day of August, 1851, and on which a patent 'as subspquently issued for a part Reissue No. 3,036, dated July ll, 1868. I
only of said applicalionthc salt fluxand dated. the 12th day of February, 1856, and on which a reissue was grantedon an amended specification and renewed petition and statement, filed on oath bearing date the 31st day of May, 1864-, and covering and embracing my original application of August, 185-1, for refining and deearbonizing molten iron by the employment of an air-blast; and said Letters Patent have again been reissued on the 2 311 day of November, 1865.
In the construction of the sn'ielliiig-furnace it is preferable to form a wide top or tunnel head of the furnace-stack. lt thereby affords a better ealcination and n'eparation of the ores before they descend to the smelting-point below in the stack. 7
No. l pig-iron, with a large crystallization, and a lively gray cast in the fracture of the metal, is well adapted for refining, and contains sixor seven per cent. of carbon taken up from the fuel employed in smelting the orcs. Other grades of gray pig metal can also be employed; but the proportion of carbon is less than the former kind. The process of converting the metal by uniting the same with an atmospheric air-blast forced in the carbon of the crude iron, and thereby refined into iron or steel.
Refined iron, with a given portion of carbon, forms steel of different grades, according to the amountof carbonc0ntained-from about two to one per cent, and in some kinds even .less, as the semi-steel; and the refined iron ingots have also asmallerproportion ol'earbon, which gives it the commercial value of iron. The carbon contained in crude pig metal is mixed uncombined, and during the refining process with an air-blast the condition of the carbon becomes changed into a combined state,
and the metal is converted into steel or iron The metal is taken or run from the furnace-hearth into any properly-constructed apparatus of sul'licicnt capacityaml height to contain the quantity of metal to be relined,
and made so as to allow room for themctal to rise while the blast is being forced in and ebullition is going on.
The form of the apparatus and the materials of which it is composed, so that it may resist the effect of the high heat to which it isto be is effected by increasci'lvolumc of bright flame.
subjected, need not he described, as they are well known to all those skilled in the art.
Ordinary fire-clay will not stand the intense heat created by the effect of the air-blast on the molten metal. This refining apparatus is not confined to any one particular mode of construction. ()ne mode is to tap the converted metal in the side near the bottom by removing a fire-plug stopper. A properlyarranged gate or valve can be attached for this purpose.
The introduction of the air-blastinto the refining apparatus can be effected in various ways to accomplish the decarbonizing and refining of the metal. One way is to attach'the pipes or apertures on one side to force the air through into the metal. I prefer placing them in a tangential position. The force of the incoming blast will thereby cause the liquid metal to move round or rotate in the same direetion with the blast, in pursuance of the plan patented by me May 17, 1859, and more fully shown in my reissued patent of February 10, 1863. They should be introduced at about half the depth of the metal in a downward direction.
7 To refine and decarbonizc one ton of metal, I generally use a pair of pipes to force the air through, each elevcn-eighths of an inch in diameter. These will discharge the required volume of air for one ton of metal with suificient rapidity when the proper amount of pressure is applied; or the number of pipes or apertures can be increased and made of proportionate size for the volume and pressure of the air required.
To convert a ton of crude metal will require about one thousand cubic feet of air discharged per minute under a proper pressure on the square inch to ell'ect a uniting of the air with the molten iron. The pressure of blast required will be about five pounds; but this will depend somewhat on the mode of introducing the air, and also on the size of the pipes employed and the column of metal above the same. A number of tons-at a charge is reiined in less time in proportion than a single ton; and in all cases, after the operation is finished, the refined metal should be allowed to stand some minutes to become calm before pouring.
\Vhen preparations are made, the process consists in starting an air-blast under a high pressure into the molten metal. The oxygen of the air unites freely with the carbon of the crude iron,forming carbonic gas and increased heat and the discharge of flame. An intense heat throughout the mass will be produced, and a violent ebullition takes place, with an The flame after some m'iimtcs time decreases as the process goes on and the carbon is being reduced. During the refining operation the color of the flame'passcs through various changes, by which, with the reduced flame, will indicate to an experienced. workman the quality of the product and the time to stop oil the blast, so
as to obtain the proper degree of carbonized metal converted into steel, semi-steel, or iron. When the carbon is all or nearly all out, the
flame ceases, and the product will be refined malleable iron, with only a small proportion of carbon remaining, and prepared for pouring into the ingot-molds.
The fusingpoint of pig metal is about 2,400 of Fahrenheit. Manganese requires a much higher heat, and when the oxide of thatmctal is used it has first to be reduced to its metallic state, which requires a higher heat still. It is therefore very difiicult to incorporate iron and manganese by mere ordinary fusion; but by the pneumatic process the heat of the molten iron is raised to 4,000 or 5,000", and sometimes higher, so that it 'bec lies nearly as liquid as water. ganese which is intermingled with the metal becomes thoroughly reduced, and the metal I becomes incorporated with the molten iron throughout, thus producing a metal greatly improved in quality over other irons, and add-' ing much to the value of the refining process above described.
Having described how therefining is accomplished in a refining apparatus, I will state howit may be done in the furnace-hearth, the
former being preferable.
The"-,tuyere-pipes employed to force the air through are introduced at one of the tuyere arches, or in front, under the temp-stone E,
through an aperture in the damplate 6:, and of suliicient length to dip down into the metal to discharge the blast. pipes or apertures to force the air through are made of black-lead, or of pure soapstone, 'or of any material that will resist the heat.
The pneumatic p roccss for converting crude iron by the use of an air-blast is a process of expansion of the crude iron in ahighly-heated condition, which cannot be attained by any other mode of manufacture. All the particles of the molten metal become extended in a very high degree of heat and fluidity, thereby any one mode of introducing the-blast, so as to effect therefining and decarbonizing of vthe metal. r
The oxide of man The refining The mode of melting pig-ironina refinery fire with the useof fuel tomaintain the heat, and continuing the use of the some while preparingthe, metal forthe puddling furnace,
Having described my discovery or,-.i.uvention, what I ask for in Letters Batent isl. The refining and decarbonizing of molten crude iron by the employment of an atmospheric. air-blast uniting the ox gen of the air with the carbon of the crude metal, and therein the manufacture of bar-iron, has long been ganese and iron as t by deoarbonizing or pku'tially decarhonizing and refining the same, thus preparingit to be molded into ingots or fine caststeol.
2. Ido not elaim,broadly,theal hat has beforebeen done; oying when efi'eeted by the e oxide of manganese, as y which the ore is not only loying of nanbut I claim such all introduction of th above described, 1)
iredueed, hut the me tal is thoroughly fused and incorporated with the iron through the instrumentality of the igh heat pr'oduoed by the air-blast, in the manner above shown.
3. The use of a, compound consisting of common salt and ma tergent in said process, as set forth.
CHRISTIAN SHUNK Witnesses:
J'nmns HmsoH, J. V. CAMPBELL.
nganese as a flux and de-