US604728A - Process of producing spiegel or similar iv - Google Patents

Description

UNITED STATES EDMUND A. S. CLARKE,

Pn'rnn'r I OFF CE.

OF CHICAGO, ILLINOIS.

PROCESS OF PROD UC'ING SPIEGEL O'R SIMILAR METALLIC ALLOY.

SPECIFICATION forming part of Letters Patent No. 604,728, dated May 31, 1898.

' Application filed November 28, 1894.

of steel manufacture as at present generally practiced the final stage is the addition to the more or less completely decarbonized molten metal within the converter or'open-hearth furnace of carbonized manganiferous iron, usually spiegeleisen, (or spiegel, as it is commonly termed,) in definite proportions, so as to communicate to the mixture the desired amount of carbon and of manganese and supplement, if necessary, the percentage of silicon. The usual method of producing the spiegel consists in charging a blast-furnace with the manganiferous ore from which it is to be made, and from time to time the furnace is tapped andthe metal run out into pigs, as in ordinary blast -'furnace operation. It is found that from one cause or another (such as a leaky twyer or the like) the percentage of manganese and silicon contained in the pigiron will frequently vary to a considerable extent not only in the pigs produced at difierent heats or casts from the same furnace, but even a very material variation in the manganese and silicon content is often found in pigs obtained from dilferent parts of the same cast 01' heat. The pigs thus produced are remelted in a cupola; but owing more especially to the variations in the manganese and sili- ,con contents above noted it is the practice to analyze the pigs and sort and stack them in separate, piles, so that the cupola may be charged with such pigs as contain the proper amount of manganese and silicon necessary to give the desired percentages in the spiegel that isto be delivered to the converter or open-hearth furnace in order to impart the predetermined amount of carbon and manganese and silicon to the charge. A number of serious objections exist to this common method of producing steel in the Bessemer Serial ll'o. 530,238. (No specimens.)

converter or open-hearth furnace, considered as an entirety. In the first place the time and labor required in casting the melted spiegel into pigs, in transporting and handling these pigs, the fuel, labor, and repairs incident to melting the pigs in a cupola, and particularly the loss of manganese and silicon by oxidation in the remelting of the pigs within desired time a serious inconvenience in theoperation. of the plant frequently results. Yet notwithstanding these objections this method above mentioned is still followed.

Indeed, although it may be practically possible to use spiegel direct from the smeltingfurnace as a recarburizing addition to the charge of a Bessemer converter or open-hearth furnace in plants at which sudden changes in the grade or character of the, spiegel are not required, still at many plants the difierences in the percentages of manganese, carbon, silicon, or the like called for by the specifications for dilferent work to be done render it important that corresponding changes in the grade or character of the spiegel s'hallbe made on very short notice, since otherwise serious delay in operation may result.

In modern" practice of steel-making the present specifications for carbon, silicon, and manganese in the steel areso rigid and exact and the limit of variation allowed so slight that if the spiegel vary considerably either in manganese or silicon, or both, it cannot be used, variations from the predetermined per centage of manganese being specially objectionable. Yet a desired change in the grade or character of spiegel from a blast-furnace cannot be made with certainty in less than from twelve to twenty-four hours.

Recognizing the desirability. of so improving the process of producing steel in the Bessemer converter or open-hearth furnace that the necessity of casting thespiegel into pigs and subsequently remelting such pigs in a cupola may be avoided, while at the same .time enabling the desired changes in the grade and character of the finished product of the converter or open hearth to be quickly and economically effected, I have devised the improvements in the Bessemer or open-hearth processes of producing steel hereinafter described, and particularly defined in the claims at the end of this specification.

In the preferred manner of practicing my invention a blast-furnace of usual or suitable construction is burdened so as to produce a spiegel of such manganese content thateven in the greatest ordinary variation of product from the normal product of the furnace the manganese will still remain higher than the highest manganese percentage that it is proposed to use in the spiegel to be delivered to the Bessemer converter. The smelted spiegel tapped from the furnace will be delivered into a ladle or other vessel, and thereby transported to a mixing-chamber of suitable construction-such, for example, as is employed at various steel-works in this country for receivin and mixing the charges of pig metal from the blast-furnaces preparatory to g the delivery of such metal to the converters. The spiegel thus tapped from the furnace and with the percentages of its constituents properly determined will have added thereto in the mixing-chamber such quantities of pig-iron or other iron silicon alloy either direct from a blast-furnace or from a cupola (or both) as will give the desired percentages of manga nese, carbon, and silicon in the final mixture. If the mixture thus obtained by adding pigiron to the metal from the spiegel-furnace is found to contain the desired percentage of manganese, silicon, and carbon, it will be tapped from time to time from the mixingchamber and delivered to the converters or open hearths at the end of the blow in usual manner. If it be found, however, that the molten mass of metal within the mixingchamber is still too high in magauese,more igiron of the ropersilicon content will be ad ed,

whereas if it be found that the metal within the mixing-chamber is too low in manganese then additions of spiegel direct from the spiegelfurnace or from a cupola and containing a higher percentage of manganese will be made in order to raise the manganese percentage of the metal in the mixing-chamber to the desired point. Should the spiegel delivered from the spiegel-furnace be found to be too high or too low ,in the silicon content to give the desired amount of silicon in the mass of proper percentages of manganese and silicon are obtained. A spiegel having the desired content of silicon, manganese, and carbon having been thus obtained, a proper quantity thereof will be introduced into the converter or open hearth at the end of the blow or refining operation in the usual manner. Hence it will be seen that by my process not only is the necessity of casting the spiegel into pigs and subsequently remelting such pigs in a cupola avoided, but by my invention the desired changes in the grade or the character of the.product of the converter or open hearth can be readily and economically effected by varying the grade or character of the spiegel while it is still in the molten condition in which it comes from the blast-furnace.

Let it be assumed, for illustration, that the desired grade of spiegel is to contain sixteen per cent. manganese and 1.70 per cent. silicon and there is delivered to the mixing-chamber from the blast-furnace, say, forty thousand pounds of spiegel containing twenty-four per cent. manganese and 1.50 per cent. silicon.

'To get the desired mixture, I would add twenty thousand pounds of pig-iron containing 2.10 per cent. silicon. From this total amount of sixty thousand pounds there may be used by the time the blast-furnace casts spiegel again, say, forty thousand pounds, leaving twenty thousand pounds. I get from the furnace by this cast, say, fortythousand pounds ofspiegel containing twenty-five per cent. manganese and 1.60 percent. silicon. gives a mixture in the mixing-chamber .of sixty thousand pounds containing twenty-two per cent. manganese and 1. 63 per cent. silicon. To bring this to the desired composition, I add twenty-two thousand five hundred pounds of pig-iron containing 1.88 per cent. silicon,

This

making in all eighty-two thousand five hundred pounds of the mixture. From this I use, say, forty-two thousand five hundred pounds, and then desire to change to a mixture containing twelve per cent. manganese .and 1.80 per cent. silicon. To do this, I add thirteen thousand three hundred and thirty-three poundsof iron c0ntaining2.10perceut.silicon, making fifty-three thousand three hundred and thirty-three pounds of the desired mixture. I use, say, from this mixture until there are twenty thousand pounds remaining and then desire to change back to the first mixture of sixteen per cent. manganese and 1.70 per cent. silicon but at such time it may be found that the furnace is making spiegel containing twenty-two per cent. manganese and 1.40 per cent. silicon. Of this, to obtain the desired manganese in the mixture, I would need thirteen thousand three hundred and thirtythree pounds, but this would give but 1.66

per cent. silicon and only thirty-three thousand three hundred and thirtythree pounds of mixture. I would therefore take the entire cast, say forty-five thousand pounds, which would give sixty-five thousand pounds of a mixture containing 18.92 per cent. manganese and 1.38 per cent. silicon. To bring the mixture to required manganese and silithe blast-furnaces, and the advantages and economies resulting from this process would be but slightly aifected thereby.

It is manifest that by my improved process above described not only is a great saving eifected by avoiding the remelting of the spiegel in a cupola, but I am enabled to change the character or grade of the spiegel upon very short notice, and even between heats of the converter or open hearth,-so that a very material saving in the practice of producing steel by the Bessemer or open-hearth processes is efie'cted.

While my invention has been defined more especially with a view to the use of spiegel, it is manifest that it may be followed in the use of other alloys suitable for additions to the charge of a Bessemer converter or openhearth furnace. So, also, it is obvious that modifications in the precise practice of my invention as hereinbefore defined may be made without departing from the spirit of the invention. Thus, for example, if it is desired to suddenly change the character of the spiegel that is to be delivered to the charge of a Bessemer converter or openhearth furnace and to use but a very small quantity of such changed mixture-as, for example, in running a few heats only of the converter or open-hearth furnace-then it would not be necessary to change the character of the entire mass of metal within the mixing-chamber, particularly if the chamber be of large capacity. In such case I would tapfrom my mixing-chamber into a suitable ladle a quantity of the spiegel and would then add to the ladle a suitable quantity of molten pig-iron or spiegel, or both, sufficient to give to the mass of molten mixture within the ladle the precise character or grade of spiegel desired for the few heats of the converter or open-hearth furnace that are to be made with such spiegel. Under such conditions the ladle would then serve as a mixingchamber; but manifestly the broad feature of my invention would be followed, because in such ladle, thus serving as a mixing-chamber,

the character of the spiegel would be varied possibility of employing spiegel direct from the spiegel-smelting furnace as a 'recarburizing condition to the charge of a Bessemer converter or open-hearth furnace; but I do not wish this to be understood as of my invention. In its broad feature my invention consists in improving the Bessemer or open-hearth process of producing steel by modifying or changing the grade or character of the spiegel from the smelting-furnace and while still in the mol ten condition in which it is delivered from such fu rnacei. e. without remeltingin order to better adapt it for use and in order to enable changes in the grade or character of the spiegel required by different kinds of work to be quickly elfected and thereafter, while still in such molten condition, adding such spiegel after the blow or refining operation to the charge of the converter or openhearth. While I have described what I regard as the preferred manner of carrying out this broad feature of invention, I do not wish the invention to be restricted to such precise process, since manifestly variations in details of process treatment may be made without departing from the spirit of the invention;

Having thus described the invention, what I claim as new, and desire to secure by Letters Patent, is-

1. The hereinbefore described improvement in the process of producing steel in a Bessemer converter or open-hearth furnace, that consists in charging the converter or open hearth with molten iron and. thereafter delivering to said converter or open hearth,

after the refining operation, a proper quan-- tity of a molten metallic alloy (such as spiegel) while still in the molten condition in which it is received from the smelting-furnace (i. e., without remelting) suitable additions in proper quantity being made to said molten metallic alloy, before its delivery to the converter, in order to impart to said alloy a character that shall adapt it for use as an addition, after said refining operation to the charge of the converter or open-hearth furnace.

2. The hereinbefore described improvement in the process of producing steel in a Bessemer converter or open-hearth furnace, that consists in smelting a manganiferous ore adapted to produce a metallic alloy for an addition' to the charge of said converter or openhearth furnace, then delivering said alloy in molten condition from the smelting-furnace into a suitable mixing-chamber and therein adding to the charge of the mixing-chamber a further quantity of molten metal containing one or more agents (such as manganese, silicon, carbon, or the like) in proper quantity to give to the mass of metal within the mixing-chamber the desired grade or character, and thereafter adding a quantity of said molten metallic alloy from said mixing-chamber to the mass of metal within the Bessemer converter or open-hearth furnace at the end of the refining operation.

3. The hereinbefore described improvement in the process of producing steel in the Bessemer converter or open hearth furnace, that consists in charging a smelting-furnace with ore sufficiently high in manganese to give to the smelted metal a'percentage of manganese in excess of that required to be delivered to the converter or open hearth as a recarburizing addition at the end of the rev and in proper quantity to bring the mang nese and silicon contents of the mass of metal within the mixing-chamber to the desired per centages, and finally adding a quantity of said molten metal from said mixing-chamber to the mass of metal within the Bessemer converter or open-hearth furnace at the end of the refining operation.

EDMUND A. S. CLARKE.