USRE13264E

USRE13264E - palmes

Info

Publication number: USRE13264E
Authority: US
Inventors: William R. Palmes
Original assignee: F Owe
Filing date: 1911-01-28
Publication date: 1911-06-27

Description

No Drawing. Original No.'924,925, dated June 15, 1909, Serial No. 48LQ25.

\ ordinarily lllIIQStOIIQ, forms a slag which ab UNIT -i) STATES PATENT onincn.

WILLIAM B. PALMER, OF BBIDGEPORT, CONNECTICUT, ASSIGNOR OF ONE-HALF TQ FRANK A. WILMOT, 0F BBIIDGEPORT, CONNECTICUT.

- PROCESS OF PRODUCING- I-IIGH-GRADEE STEEL FROM LOW-GRADE MATERIAL.

January 28, 1911.

Specification of Reissued Letters Patent. R issued June Serial No. 505,336,

State of Connecticut, have invented certain new and useful Improvements in Processes of ProducingIIigh-Gi'ade'.Steel from Low- GradeMaterial; and I do hereby declare the following to be a 'full, clear, and exact description of the invention, such as will en able others skilled in the art to which it appertains' to make and use the same. In basic open-hearth steel making it has heretofore been necessary to use for a considerable portion of the charge steel-making pig iron commercially known either as basic, or off-basic or Bessemer pig, the basic pig not exceeding one per ccntt in silicon and the off-basic or Bessemer pig not exceeding one and one-fourth per cent, in silicon, Whereas foundry pig iron from which castings and eastiron borings are produced exceeds both basic and oil basic pig in silicon, phosphorus and sulfur and its scrap makes too acid a bath to permit of any considerable portion of the scrap being used in basic open-hearth furnaces because of the acid bath attacking the basic lining of the furnace at steel-marking temperatures, the silicon being particularly active in attacking the basic lining.

The ordinary process of making basic open-hearth steel consists in charging a furnace with pig iron and scrap together With the necessary flux and then melting and working this charge to the desired chemical composition and temperature. The flux,

sorbs and retains the impurities, silicon, sulfur and phosphorus, to a greater or less-extent dependent on the basic qualities of the slagso formed; thereby purifying the meta]. Simultaneously, however, with the'oiiidation of the impurities-the carbon alsois partially oxidized and the furnace must be charged with sutlicient carbon in some form to cor-er thisloss by oxidation and to insure sufficient carbon remaining in the bath after the 'rnetailic charge is melted. This required caricon is generally contained in the pig iron,

and the furnaccniust therefore be cl1arged .of pig iron greatly increases the cost of the steel.

Application for reissue filed- My present invention enables me to greatly reduce the cost of production of high grade steel. This I accomplish by using-in lieu of pig iron, materials that are commercially' Wort-h one-half, 1nore or less, the cost of pig iron, as for example cast iron horings,

large pieces of castings, casts-crap and other low grade material which cannot be used in any appreciable quantity in the ordinary open-hearth process on account of the high heart-h steel for the reason that the percent age of silicon in cast iron borings is so much; higher than 1n baslc pig iron as to cause the destruction of scorification of the-furnace hearth, and the neutralizing and destroying of the basic effect of the limestone and inter.- fering with the removal of the other iinpu .1- ties. The percentage of sulfur isalso much higher in cast iron borings than in pig iron owing to the absorption of sulfur from the fuels in former .meltings, Sulfur, in fact. is the most difiicnlt impurity to remove or oxi dize from the bath, and if not removed or oxidized greatly decreases the quality and value of the steel. Still another reason Why cast ironborin'gs cannot be used in the ordinary open hearth process of making steel is their physical condition, they "being finely granular or powdered, which renders them unfit for use in appreciable quantity in the tion interferes with the melting, the material lying in such close'mass that the'heat mynovel process and the physical and chezn ical characteristics-thereof, it will be sit-iii-- cient to refer to them geimrically as low grade material.

In carrying out my invention I use two or,

more. open-hearth furnaces, the first of." which I call the prnnary :lurnace and the it I .lic iron or iron oxid, tities and as rapidly as the melting will per-- cient incline to permit it other or others secondary or finishing furnaces, furnace will keep from two to four secondary furnaces running, depending of course upon the size of the furnaces. The primary furnace I run at what is relatively a low temperature in steel making for example, at a temperature one thousand degrees F ahrenheit, more or less, below perature of steel making. furnace or furnaces are run at ordinary steel-making temperatures.

The running of the primary furnace at a relatively low temperature prevents any appreciable attack of the silicon on the basic lining of the .furnace and also partially eliminates the silicon, phosphorus and sulfur. From this primary furnace I tap for use in the secondary furnacea molten metal representing in analysis a semi-pig or semisteel, it being refined as to silicon, phosphorusnnd sulfur to about one-half of the percentage of these elements contained in basic pig iron, the further refinement at steelmaking temperatures The primary furnace may be of the tilting type and the secondary furnace or furnaces of the stationary type. In starting, the primary furnace is charged with pig iron or with large chunks 'or pieces of cast iron to form a liquid bath of iron to which visadded sufficient flux to cover the metal and to partially oxidize the impurities at the same time preventing oxiation of the metal. It should be noted that this is done only in starting the primary furnace, as thereafter in the primary furnace to form the bath.

After the bath is so formed the low grade material as already defined, either as metalis' added in such quanmit together with the required amount of flux in the shape of limestone or other materials cold or in the shape of fluid slag from the finishing furnace or furnaces, as will be more fully explained.

The secondary or finishing furnace is partially charged with'any low grade material as scrap and a sufficient quantity of flux and when the heated metal is in semi-molten condition it is ready for the molten metal from the primaryfurnace.

In transferring the molten metal from the primary furnace to a secondary furnace, if the secondary furnace is at a low enough level, the molten metal may be poured from the primary furnace into a trough at sulfito flow into the This arrangement is not with furnaces already in use. Ordinarily in transferring the metal I pour it from the primary furnace into a ladle which is handled by a crane. Suppose now that the partial charge in the secondary secondary furnace. common, however,

for the reason that a single primary the ordinary tem- The secondary being accomplished in the secondary furnace.

sufficient ,metal is left and the metal delivered thereto from the f ladle. It will be noted that a sufficient quantity of the molten metal, one-half more or less of the charge, is left in the primary furnace. This molten metal in the primary having lost itsefiiciency is removed. ,VVhen the charge in the secondary furnace has reached. the proper condition it is drawn off in the usual manner. The eificiency of the slag from the .secondary furnace, however, has been only partially impaired by the operation'of said furnace. After the tapping of the heat of steel from the secondary furnace the slag fromsaid furnace may or may not be run into the ladle and transferred to the primary furnace to assist in the working of the charge therein. This charge of molten slag from the secondary furnace assists to a certain extent in working the charge in the primary furnace and also acts to partially remove and retain the impurities from the charge in the primary furnace. As this slag is charged in a molten condition, there --is no cooling effect produced by it and no retarding of the work of the primary furnace. The charging of the slag from the secondary furnace into theprimary furnace has this completion of the refining operation andleaving suflicient molten metal in the pri mary furnace to form a molten bath for the next charge of low grade material, I avoid the necessity for the use of pig iron or any high grade material to furnish the necessary amount of carbon and produce a high grade of steel from a low grade of material. The operation at the secondary furnace greatly hastened by the additon of the charge of molten metal from the primary furnace. As

furnace forms a bath Whichfacilitates and further beneficial effect of immediately pro- The essential.

the charge in the secondary furnace is already infasuitable condition, the more or less violent reaction produced by the'charge of 'inolten metal from the primary furnace will remove the-impurities .very rapidly}. I find in praeticef thatffuignaces operated by this process produce" as much, or more, steel I from a' charge of low gradeinaterial as from an ordinary .pig iron and scrap charge, and that the ste'e so produced is fully equal in physical qualities and chemical composition steel, the process which'consists in charging a primary furnace with low grade material of the character described, operating said furnace at a temperature. materially below ordinary steel-making*temperatures, partially charging a secondary furnace with low grade materialfoperating said'furnace at ordinary steel-making temperatures and transferring a portion of the charge of the primary furnace to the secondary furnace for the completion of the refining operation leaving a portion of the charge in the primary furnace to form a bath to receive the next charge of low grade material.

2. In the manufacture of open-hearth steel, the process which consists in charging a primary'furnace with low grade material of the character described, operating said furnace ata" temperature materially below ordinary steel-making temperatures, partially charging a secondary furnace with. scrap and flux, operating said furnace at ordinary steel making temperatures and transferring a portion of the charge of the primary furnace-to the secondary furnace for the completion of the refining operation, leaving a portion of the charge in the primury furnace to form a molten bath to'receive the next charge oflow grade material.

In the manufacture of open hearth steel, the process which consists in charging a primary furnace with low grade material of the character described, operating said furnace at a temperature materially below ordinary steel-making temperatures, partially charging asecondary furnace with low grade material and flux, operating-said furnace at ordinary steel-maklng tempera- ,tures, transferring a portion of the charge from the primary furnace to the secondary furnace for the completion of the refining operation, leaving a portion of the charge in the primary furnace to form a molten mary furnace with low grade material of the chaiqacter described, operating said furnace at \a temperature materially below ordinary "steel-making temperatures to partially refine the same, transferring charges of the partially refined material from said primary furnace to a basic open-hearth furnace, and reducing the same into steel.

5 In the mianufacture of open-hearth steel, the process -which consists in charging a primary furnace with low grade material of the character described, operating said furnace at a temperature materially below ordinary steel-making temperatures, maintaining a bath of moltenmetal in the primary furnace, and'itransferring charges of said partially refined bath from time to time to a basic open hearth furnace, and re fining the same in to\ steel. v

6.- In the manufacture of open-hearth steel, the process which consists in charging 'a primary furnace with low grade material vof the character described, operating said furnace at atemperature materially below ordinary steel-making temperatures, partially charging a secondary basic open-hearth furnace with other metal, and transferring a'portion of the partially refined charge of the primary furnace to the secondary furnace to complete the charge, and reducing the same into steel in said secondary open-hearth furnace.

In testimony whereof, I have hereunto set my hand this 23rd day of January 1911.

Witnesses QLAMES J. PHALEN,

DANIEL A. KBATING.