126,923 UNITED STATES PATENT OFFICE,

TEIOMAS S, BLAIR, OF PITTSBURG, PENNSYLVANIA. IMPROVEMENT IN THE MANUFACTURE OF WROUGHT-IRON AND STEEL FROM IRON SPONGE, s Specification forming part of Letters Patent No. 126,923, dated May 21, 1872.

SPECIFICATION. vary under varying conditions of manufacture. To all whom it may concern: Under ordinary circumstances the sponge can Beit known that I, THOMAs S. BLAIR, of be produced at much less expense than the pig Pittsburg, in the county of Allegheny and iron, and it costs also much less to work the State of Pennsylvania, have invented a new mixed charge than it does to work the pig-iron and useful Improvement in the Manufacture alone. So far as the process of working the of Wrought-Iron and Steel from Iron Sponge; mixed charge is concerned, the introduction and I do hereby declare the following to be a of the sponge makes no difference other than full, clear, and exact description thereof. is due to the greater rapidity with which the My invention relates to the manufacture of pig-iron comes to nature. WTOught or malleable iron and steel from iron The second method dispenses with the use Sponge, prepared by ther deoxidation without of pig-iron, the sponge being worked alone. fusion of iron ore. For this purpose I use a reverberatory-furnace In another specification I have fully de with cinder bottom. The charge of iron sponge scribed the apparatus I employ, and the pro is thrown into the heated furnace and is treated cess I use in deoxidizing the iron ore for the as if it were minutely-divided wrought-iron production of metallic sponge. It is therefore Scraps, (such as fine borings or turnings of unnecessary to say more here in regard to the Wrought-iron,) with one exception, which I will production of the sponge, than that by my pro proceed to describe. The sponge is, when heate cess the ore is almost entirely deoxidized, suf. ed to a red heat, extremely sensitive to oxygen, ficiently so, at least, for all practical purposes much more so than finely-comminuted wrought in the production therefrom of iron and steel; iron, and has also a considerable quantity of and, also, that when the sponge is delivered mineral matter intimately associated with it. from the reducing-furnace it is cold, or at least If, therefore, it were simply placed in a re So nearly so as not to be liable to oxidation verberatory-furnace and heated to a welding from contact with atmospheric air. heat and then balled, there would be an ex In the manufacture of wrought-iron from cessive waste, and the quality of the iron pro iron sponge I employ either of the two methods duced would not be good. This fact which hereinafter described. The first method may constitutes the main difficulty of working iron be regarded as an adjunct to the puddling pro sponge into malleable iron, renders it neces cess. Its essential feature is the imparting of sary to use some means for protecting the the sponge to the charge of pig-iron in the minute particles of iron which constitute the puddling-furnace at any time after the pig-iron sponge from oxidation. This I accomplish by has been melted-that is to say, the sponge supplying the charge of sponge, either before may be charged into the puddling-furnace as or after introducing it into the furnace, with soon as the pig-iron has become liquid, or it some substance or substances having affinity may be added in small quantities from time to for the foreign mineral matter associated with time during the working of the heat, or it may the sponge, so that under the heat of the fur be thrown in after the iron has come to nature nace they will combine and form a glass, there and during the balling. It is wasteful to in by not only fluxing out the impurities from the troduce the sponge into the puddling-furnace iron, but also forming a protecting coating to before the pig-iron is melted, but after that it the particles of sensitive iron. For example, may be profitably used at any stage of the if the sponge is found to contain an excess of process of bringing the pig-iron to nature. The silica, I add to the charge either the protoxide effect of the addition of the iron sponge to the of iron, (which is always at hand in the form charge of pig-iron is that it facilitates and of scales, hammer-slag, &c.) or basic minerals, hastens the coming to nature of the iron and such as lime, alumina, &c. Should lime be improves its quality. So far as the success of present in excess in the sponge I add alumina the operation is concerned, any relative pro or silica. The kind of flux to be used depends portion of sponge and pig-iron may be used. therefore on the character of the foreign mat The most profitable ratio will be determined ter existing in the iron sponge, the important by their relative cost of production, which will point being to supply a fluxing substance which

2 126,923 will combine with the foreign matter in the the condensation. The comminuted sponge is sponge at a sufficiently low heat to make a then heated red hot, and in that condition is cinder or glass, and thus furnish the desired subjected to powerful compression. While protection to the particles of iron. When clay thus heating the sponge it is, of course, all im or other substances which dissolve in water portant to protect it from oxidation, which are employed as the fluxing and protecting would occur if it were exposed to contact with material, I prefer to add water enough to them the atmosphere. This I effect by packing to make a thin paste before mixing with the the sponge powder, or partially-compressed sponge. Then I stir this paste and the sponge sponge, in cases made of iron, fire-clay, or together until a thorough coating of the latter other suitable material which will bear the is produced. The furnace should be so ar requisite heat and protect their contents from ranged as to admit as little free oxygen as pos the atmosphere. These cases may be made of sible into the working-chamber. On this ac any convenient size and shape in cross-section, count I prefer to use Siemen's regenerative having parallel sides and closed at top by a furnace for this purpose. Thus treated, the loose cap or follower. The cases are then heat sponge, as soon as sufficiently heated, comes ed to redness in a muffle, and each case is to a welding state and can be readily balled, placed in a clamp, so as to support the sides after which it may be manipulated in the same of the case and prevent its bursting. Press way as puddle-balls. - ure is then applied to the cap or follower, by I will now proceed to describe my method means of screw, hydraulic press, or otherwise, of making steel from iron sponge. until the red-hot mass is sufficiently condensed. In speaking of “steel” as contradistin Instead of using a case, as described, the guished from “wrought-iron,” I wish to be un comminuted sponge may first be compressed derstood as meaning by the latter term iron while cold, which will cause the particles to associated with so small a percentage of car cohere into a solid mass. The block thus ob bon that it cannot be manipulated in a molten tained is then coated with mud or other simi state, and by “steel' any malleable carbide of lar adhesive preparation which will resist the iron that is capable of being cast into an ingot. action of the heat and protect the iron from . In order to make steel from iron sponge I the air. These blocks are then heated and subject it to fusion, in presence of the proper subjected to further pressure to give them the proportion of carbon, either in a crucible or density required, which is easily obtained if a upon the open hearth. I will first describe the fair red heat is employed. crucible treatment. In order to make this pro It has been usually assumed by inventors cess economically successful it is essential that and others that if a really pure metallic iron the crucible shall contain a charge sufficient sponge could be procured nothing further in quantity to yield as large a product as is would be necessary to make good steel there obtained by the existing methods of making from than to treat it in the crucible simply as cast-steel in crucibles. The sponge, however, if it were wrought-iron. This, however, is sel is so very light in texture that, unless highly dom the case, as it only occurs when the ore compressed, it is impossible to charge a suffi which has been reduced to sponge happens to cient amount into the crucibles. Chenot en contain the proper balance of acids and bases deavored to obviate this difficulty and give to form a glass, thus preventing the combina the required density to his deoxidized ore by tion of the mineral impurities with the steel, pulverizing it and compressing it when cold. which would greatly deteriorate the quality or He did not succeed, however, owing no doubt render it worthless. to the imperfection of the article produced by The ores chiefly employed in the United his deoxidizing process, or, rather, to the fact States in the manufacture of steel contain over. that his product was not really metallic sponge, ninety per cent of oxide of iron, the residue but a conglomerate of more or less perfectly being foreign substances which usually contain reduced ore, so that he was not able by com an excess of silica, which is not removed by pression to cause the particles to unite and the process of reduction from oxide to metal give the requisite density to the mass. It is, lic sponge. At the high temperature employed therefore, essential to the economic success of in the melting furnace, and in the presence of the process of making steel in crucibles from the free carbon introduced with the charge into iron sponge that the Sponge itself should have the crucible, a considerable quantity of this such a degree of purity as to be practically silica would be reduced, and the resulting sil free from particles of solid carbon, and also icon would be more or less infused into the consist of particles thoroughly and uniformly steel, probably rendering it worthless. In or reduced. This I effect by my peculiar process der to obviate this difficulty and supply the of making iron sponge described in a separate requisite balance for the silicic acid Imix with specification before referred to. the comminuted Sponge, before pressing, a suf In order to secure the requisite density of the ficient amount of finely-pulverized lime, the sponge for the crucible treatment I cause it to quantity being dependent upon the propor be ground or finely pulverized, so that the dis tion of silica in the sponge. The result of integration of the spongylumps may not have this presence of lime in the sponge is that, be to be performed by the power applied to effect fore the temperature of the crucible has

126,923 3 reached the point at which the reduction of perature employed in the Siemens-Martin the silica into silicon by carbon would take process, and will mingle with the other slag, place, the lime and silica have united to and thus pass off without contaminating the form a glass which thereafter remains neu steel. tral, and, holding the silica in combination, This process of making steel by the use of prevents its contaminating the steel. Should sponge possesses great advantages over any the sponge contain lime in excess, sand or other hitherto employed, both as regards the clay is added to the sponge powder, so as cost and quality of the product. Especially to present silica or alumina to the basic in is this the case as compared with the pneu gredients, and thus prevent their entering into mattie process, inasmuch as the sponge can, in combination with the steel. Iron sponge thus many localities, be produced at much less cost prepared by the systematic admixture of suit than pig-iron, and as the sponge has suffered able fluxing ingredients, and by red-hot com none of the contaminations of the blast-fur pression can then be used in crucibles in like nace, the result is a much higher grade of manner as Wrought-iron for the manufacture steel than that obtained where wrought-iron of steel. made from the pig is the stock used. The other method of making cast-steel by Having thus described my improvement in means of metallic iron sponge is by melting it the manufacture of iron and steel, what I claim on an open hearth. This method, (known as as my invention, and desire to secure by Let the Siemens-Martin process,) as heretofore ters Patent, is practiced, consists in melting a charge of pig 1. In the manufacture of Wrought-iron by iron in the hearth of a Siemens furnace until the puddling process, the adding of iron sponge it reaches a high white heat, and then adding in a cold state to the pig-iron after it is melt to the bath of melted metal successive charges ed in the puddling-chamber, substantially as of Wrought-iron previously brought to a bright and for the purpose hereinbefore described. red heat, which imbibe the carbon from the 2. The manufacture of Wrought-iron from pig-iron, and are melted therein, thereby form-- iron sponge by the treatment of the sponge ing a homogeneous mass of steel, the quality previously mixed with a suitable flux for pro of which, as to hardness, is regulated by the tecting the particles of metal from oxidation, proportion of Wrought-iron used, or by the ad substantially as hereinbefore described. dition of more pig-iron. For this purpose I 3. In the manufacture of steel from iron substitute metallic sponge for the ordinary sponge by the crucible process, the treating of malleable iron. The former being much more the iron sponge while protected from oxidation, sensitive to carbon, and more easily acted and compressing the sponge while in a heated upon, shortens the process and improves the condition, substantially as and for the purpose result. The sponge may be supplied to the hereill before described. cast-iron bath in either of three different ways: 4. In the manufacture of cast-steel from iron First, the sponge may be charged into the sponge by the crucible process, the mixing of bath of melted metal from time to time with a suitable flux with the iron sponge to neutral out previous heating or compression; or, sec ize the action of the silicic acid or other for ond, it may be first compressed into blocks, eign ingredient therein, previously to the heat in which case it may, if preferred, be heated ing and compression thereof, substantially as red-hot before being charged; or, third, the and for the purpose hereinbefore described. sponge, before being charged, may be pre 5. The manufacture of cast-steel from iron viously brought to a plastic condition in a sep sponge by melting the iron sponge in a bath arate furnace. It will readily be seen that the of molten pig-metal, the iron sponge being di sponge, by reason of its comminuted condition rectly charged in a loose cold state, substan- . and porous texture, is more readily mixed with tially as hereinbefore described. the melted cast-iron than ordinary wrought 6. The manufacture of cast steel from iron iron, and being extremely sensitive is more sponge by charging the iron Sponge in masses rapidly melted. It might be supposed that previously compressed and heated, or in a the sponge, being reduced directly from the plastic condition, into a bath of molten pig ore, and not subjected to any process for re metal, and melting it therein, substantially as moving the silica, could not be thus used for and for the purposes hereinbefore described. making steel without special fluxing. This, In testimony whereof I, the said THOMAS however, is not the case, as it has been ascer S. BLAIR, have hereunto set my hand. tained that fluid cast-iron does not, in the THO. S. BLAIR, presence of silica or silicates, take up the sili Witnesses: con. The foreign ingredients present in the MoRRISON FOSTER, sponge will therefore be liquefied at the tem. THOS. B. KERR.