This was a bill in equity filed in the circuit court for the western district of Pennsylvania by the Carnegie Steel Company against the Cambria Iron Company, for an injunction and the recovery of damages for the infringement of letters patent No. 404,414, issued June 4, 1889, to William R. Jones, of whom plaintiff was the assignee, for a 'method of mixing molten pig metal.'
In his specification the patentee declares that the——
'Primary object of my invention is to provide means for rendering the product of steel works uniform in chemical composition.
In practice it is found that metal tapped from different blast furnaces is apt to vary considerably in chemical composition, particularly in silicon and sulphur, and such lack of uniformity is observable in different potions of the same cast, and even in different portions of the same pig. . . . The consequence of this tendency of the silicon and sulphur to segregate or form pockets in the crude metal is that the product of the refining process in the converters or otherwise in like manner lacks uniformity in these elements, and therefore often causes great inconvenience and loss, making it impossible to manufacture all the articles of a single order of homogeneous composition. Especially is this so in the process of refining crude iron taken from the smelting furnace and charged directly into the converter without remelting in a cupola, and, although such direct process possesses many economic advantages, it has on this account been little practised.'
'For the purpose of avoiding the practical evils above stated, I use in the refining process a charge composed, not merely of metal taken at one time from the smelting furnace, but of a number of parts taken from different smelting furnaces, or from the same furnace at different casts, or at different periods of the same cast, and subject the metal before its final refining to a process of mixing, whereby its particles are diffused or mingled thoroughly among each other, and the entire charge is practically homogeneous in composition, representing in each part the average of the unequally diffused and segregated elements of silicon and sulphur originally contained in each of the several parts or charges. By proceeding in this way, not only is each charge for the refining furnace or converter homogeneous in itself, but, as it represents an average of a variety of uniform constituent parts, all the charges of the converter from time to time will be substantially uniform, and the products of all will be homogeneous.'
'To this end my invention may be practised with a variety of forms of apparatus,—for example, by merely receiving in a charging ladle a number of small portions of metal taken from several ladles or receiving vessels containing crude metal obtained at different times or from different furnaces, the mixing being
performed merely by the act of pouring into the charging ladle, and other like means may be employed. (The clause in italics was subsequently disclaimed.) I prefer, however, to employ the apparatus shown in the accompanying drawings, and have made it the subject of a separate patent application, serial No. 289,673, and, without intending to limit the invention to the use of that specific apparatus, I shall describe it particularly, so that others skilled in the art may intelligently employ the same.'
'My invention is not limited to its use in connection with converters, since similar advantages may be obtained by casting the metal from the mixing vessel into pigs for use in converters, puddling furnaces, or for any other uses to which pig iron may be put in the art.' (This paragraph subsequently disclaimed.)
(The apparatus is represented by the drawing here inserted.)
[NOTE: MATERIAL SET AT THIS POINT IS NOT DISPLAYABLE (GRAPHIC OR TABULAR MATERIAL)]
'Referring now to the drawings, 2 represents the reservoir before mentioned. It consists of a covered hollow vessel having an outer casing 3, of iron or steel, which is suitably braced and strengthened by interior beams and tie-rods, as shown in the drawings. The whole exterior of the vessel is lined with fire brick or other refractory lining, which should be of suffi-
cient thickness to retain the heat of the molten contents of the vessel and to prevent chilling thereof. The vessel is strongly braced and supported by braces and tie-rods, and may be of any convenient size, holding, say, 100 tons of metal (more or less), and its shape is preferably such as shown in the drawings, being rectangular, or nearly so, in cross section and an irregular trapezium in longitudinal section, one end being considerably deeper than the other. At the top of the deeper end, which I call the 'rear' end, is a hopper 5, into which the molten metal employed in charging the vessel is poured, and at the front end is a discharge spout 6, which is so located that the bottom of the spout is some distance above the bottom of the vessel,—say 2 feet in a hundredton tank, and more or less, according to the capacity of the vessel,—the purpose of which is that when the metal is poured out of the spout a considerable quantity may always be left remaining and unpoured, and that whenever the vessel is replenished there may already be contained in it a body of molten metal with which the fresh addition may mix. I thus secure, as much as possible, uniformity in the character of the metal which is fed to and discharged from the tank, and cause the fluctuations in quality of the successive tappings to be very gradual.'
'For convenient use of the apparatus I have found it best to so arrange it that it is adapted to receive its charges of metals from cars or bogies 7, which run on an elevated track at about the level of the normal position of the hopper 5, and to discharge its contents into similar cars or bogies 15 on a track below the spout 6. In order to facilitate the charging and discharging of the metal, the vessel is set on journals or bearings 8, which have their bearings in suitable pedestals 9, and its rear end is provided with depending rack bars 10, which are pivotally connected with the bottom of the mixing vessel 2, and are in gear with pinions 11, the shaft of which is connected by gearings 12 with the driving mechanism of a suitable engine. The pinions are held in gear with the rack bars by idler wheels or rollers 13. As the journals or bearings 8 are located on a transverse line somewhat in advance of the center of gravity
of the vessel, it tends by its own weight to tilt backward into the position shown in Fig. 1, but may be restored to a level position by driving the pinions 11, and thus raising the rack bars 10 until the front part of the bottom of the vessel comes in contact with a rest or stop 14.'
'The mode of operation of the apparatus is as follows: When the vessel is in the backwardly inclined position shown in Fig. 1, it is ready to receive a charge of metal from the car 7. Before introducing the first charge, however, the mixing vessels should be heated by internal combustion of coke or gas, and when the walls of the vessel are sufficiently hot to hold the molten metal without chilling it, it is charged repeatedly from the cars 7 with metal obtained either from a number of furnaces or at different times from a single furnace. The charges of metal introduced at different times into the vessel, though differing in quality, mix together, and when the vessel has received a sufficient charge its contents constitute a homogeneous molten mass, whose quality may not be precisely the same as that of any one of its constituent charges, but represents the average quality of all the charges. If desired, the commingling of the contents may be aided by agitation of the vessel on its trunnions, so as to cause the stirring or shaking of its liquid contents. The mixing chamber being deeper at its rear than at the front end, as before described, and its normal position, when not discharging metal for the purpose of casting, being with the bottom inclined upward toward the front or discharging end, and the obttom of the spout being situend, end, and the bottom of the spout being situate forward end, it is adapted to receive and hold a large quantity of molten metal without its surface rising high enough to enter the discharge spout.'
'The discharge spout 6 is furnished with a movable cover operated by a weighted lever 16, which, when closed, serves to exclude the outside air and prevent a draft of air through the vessel and the consequent rapid cooling of the molten contents. If care is exercised in keeping the cover closed, the metal can be kept in a fluid condition for a long time, the heat being kept up by repeated fresh charges of molten metal, and, if necessary or found desirable, by burning gas introduced by a pipe or pipes into its interior.'
'After the vessel is properly charged, the metal is drawn off into the cars 15 from time to time, as it is needed, by opening the door or cover 16 of the spout 6 and driving the engine 12 so as to elevate the rear end of the vessel and tilt it forward, and thus to discharge any required amount of its contents in the manner before explained into the cars 15, which are transported to the converters, or the metal is cast into pigs or otherwise used. (Italics disclaimed.) The tilting of the vessel does not, however, drain off all the contents thereof, a portion being prevented from escaping by reason of the elevated position of the spout 6, and as the vessel is replenished from time to time each new charge mixes with parts of previous charges remaining in the vessel, by which means any sudden variations in the quality of the metal supplied to the converter is avoided. Instead of...
