US1388335A - Grate for sintering-pans - Google Patents

Description

J. E. GREENAWALT.-

.GRATE FOR SINTERING FANS.

APPLICATION FILED 050.31.1920.

Patented Aug. 23,1921;

3 SHEETS-SHEET 2.

hi I

1. E. GREENAWALT. I GRATE FOR SINTERING FANS APPLICATION FILED DEC, 3|. 1920. 1 ,3 335. Patented Aug. 23, 1921 3 SHEETS-SHEET 3.

I I 1/ ii UNITED STATES PATENT OFFICE.

GRATE FOR SINTERING-PAN S.

Specification of Letters Patent.

. Patented Aug. 23, 1921.

Application filed December 31, 1920. Serial No. 434,212.

To (ZZZ whom it may concern Be it known that I, JOHN E. GREENA- war/r, a citizen of the United States, residing at New York, inthe county of New York and State of New York, have invented certain new and useful Improvements in Grates for sintering-Pans, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming a part hereof.

The present invention is directed to improvements in grates for ore-sintering or roasting pans in which the charge supported by the grate is subjected to the action of a downdraft current of air to supply the oxygen to the combustible components of the charge, examples of which may be found in m U. S. Patents Nos. 1,098,035 and 1,110,623, bearing date respectively May 26, 1914, and September 15, 191 1, though obviously I do not wish to be restricted in the application of the invention to ore-sintering apparatus, or to sintering apparatus of any particular type, it being apparent that the grate has a wide range of uses and may be applied in any relation where it can subserve its legitimate and natural function. The improved grate however has special application in downdraft sintering pans in which,

with grates as ordinarily constructed, con-' siderable difficulty is encountered in maintaining open channels or paths for the passage of the gases, especially at the surface from which the gases escape. One of the methods resorted to for maintaining a clear and unobstructed passage through the openings of the grate is to interpose between the charge of ore to be sintered and the supporting surface of the grate a protecting ayer of coarse porous inert material such as limestone, said protecting layer forming in effect a porous bed or hearth on which the charge to be sintered is directly supported. 'Ordinarily, this layer of inert material resting directly on the grate not only prevents the fine material composing the top layer or charge to be treated from being drawn through the openings or slots of the grate,

but is itself susceptible of ready removal from the grate. It also permits of an even flow of gases through all portions of the grate surface, thereby producing a uniform product. However, in downdraft sintering the high temperature attained in the treatment of some material is so great that con:

siderable portions of the material pass beyond the stage of incipient fusion and become molten, or sufiiciently fluent to percolate through the channels and interstices of the inert porous protecting layer deposited on the grate, the molten material. finally finding its way into the grate openings where it chills and clogs the openings and becomes fastened or adheres to the grate. To remove this adhering material from the ordinary grate, it becomes necessary to employ manual labor and much time is consumed in cleaning the grate and restoring the same to working condition. Of course, by employing a protecting layer or bedding of suffi cient thickness the difliculties alluded to may be avoided; but since this bedding is usually limestone or previously sintered material composed of pieces from one-quarter to onehalf inch in size and requiring special reparation, it is obvious that as a matter 0 economy it is desirable to employ a minimum amount thereof; and one of the objects of the present improvement is to reduce to a minimum the quantity of the material forming this bottom or protecting layer. This is accomplished by concentrating the material above the perforations or openings of the improved grate in such a manner as to not only fully protect the openings but at the same time form a layer presenting an innumerable number of passages for the traverse of the gases from the superincumbent fine material composing the charge to be treated or sintered. With the material forming the further overcome the difficulties attending the use of grates as now generally constructed, the present improvement provides means for automatically removing any accretions on the grate or any obstructions in the grate openings, such removal being accomplished by causing the grate bars to automatically participate in a rotary movement relatively to the pan when the latter is tilted or rotated to dumping position, the adjacent edges of contiguous bars rotating or revolving simul- 5 taneously in opposite directions in such rotary movement, whereby they are caused to part or separate, the edge of one bar moving upward, and the adjacent edge of a contig'uous bar moving downward, from their normal positions of proximity, this separating movement of the edges of the bars exercising "a shearing effect on the sintered andthe bars will rotate back to their normal positions with the edges of consecutive bars in normal proximity or just far enough apart to form the desired spaces or slots for separating the bars. A further object is to construct a grate-bar with the most effective cross-section not only with a view of enhancing the shearing or breaking action on the sintered material with the dumping movement of the pan as aforesaid, but with a view of forming the desired grooves or channels between successive bars for the deposit of the coarse material or bedding intended for the protection of the grate openings or slots located at the bottoms of said channels.

A further object is to provide a grate structure presentin further and other advantages more fully apparent from the following detailed description in connection with the accompanying drawings in which- Figure 1 represents a middle vertical longitudinal section of an ore sintering pan showing my invention applied thereto, onl. a portion of the grate being illustrated; Fig.

2 is a top plan of the pan.and grate bars shown in Fig. 1; Fig. 3 is an enlarged vertical cross-section of the'pan on the line 3-3 of Fig. 1; Fig. 4; is a vertical cross- -'section on the order of Fig. 3 but on a larger scale showing the dumping side of the pan, the grate-bars being shown in their normal positions; Fig. 5 is a view of the parts shown in Fig. 4 with the pan in inverted osition, showing the extent of rotary dis placement participated in by the gratebars; Fig. 6 is a perspective of one of the grate-bars detached; Fig. 7 is an enlarged longitudinal sectional detail on the line 7-7 of Fig. 3; Fig. 8 is a diagrammatic end view of three grate-bars showing the degree of rotary displacement thereof with a dumping movement of the pan; Fig. 9 is a perspective of the casting supporting one end of a series of grate-bars, and of the beari received by'said casting for the support 0 the adjacent end of a grate-bar alining with a bar supported by the casting; Fig. 10 is a view similar to Fig. 4 showing the limit of the angle through which the pan is tilted before rotary displacement of the grate-bars is arrested; and Fig. 11 is a diagrammatic end view of a modification showing alternating fixed and rotary grate-bars.

Referring to the drawings, and for the present to Figs. 1 to 10 inclusive, 1 represents a pan or treatment vessel which in practice is preferably oblong and of any convenient size, the same terminating at the ends of its longitudinal axis in hollow trun-' nions 2 about which the pan may be rotated or tilted for purposes of dumping the charge, I the passage-ways of the trunnions communicating with the stationary casings or boxes 3 (only one being shown) from which lead the pipes 4 to any suitable exhauster (not shown). The intake or inner ends of the trunnion passageways open into the gas chamber 5 disposed under the grate and the charge m supported thereon. Extending across the chamber 5 are a series of flanged tie beams 6 serving as grate supports, the ends whereof are bolted to. the side walls of the pan,- each beam bein formed with a pair of large openings 8 elongated in the direction of the length of the beam to allow for a free circulationof the gases through the gas chamber to the passage-ways of the trunnions. The features above described and others shown but not alluded to, are well understood in the art and a description thereof is unnecessary, the same being in no wise concerned with the present invention.

In the present embodiment of my invention the grate-bars 7 run lengthwise of the pan, 3 that is to say they run parallel to the rotation axis of the pan, the bars being mounted y across the beams 6 and free to rotate about their longitudinal axes. The cross-section of the bar is such that when a number of bars 1 are placed in juxtaposition the opposing faces h of successive bars will slope downward toward the spaces or slots 8 between the bars, thereby forming V-shaped grooves or channels 03 in which the coarse bedding 1 m may be concentrated, a limited depth of the material affording ample protection to the bars against adhesion thereto of the sintered, and often molten, product of the. charge. The slots or spaces 8 between the 1 bars are normally bounded by the narrow .intermediate side faces t, the upper edges 6 whereof areon the lines of intersection with the side sloping faces h of the bars, the edges 6 of the several bars being disposed in the 1 same horizontal plane for a normal position of the pan (Fig. 3), this plane being below and parallel to the plane of disposition of the tops or ridges 'r' of the bars. These ridges are preferably flat as shown, though 1 obviously I am not to be restricted to a fiat top for the bar. A flat top however affords a greater surface of support for the charge than would a rounded or sharp ridge and hence a bar with a flat top with side faces 1 diverging downwardly therefrom is the preferable construction. The cross-section of the bar is in the main that of a truncated wedge bounded on the sides by flat faces, the portion below these faces (t) being likewise a truncated wedge, but so limited in extent as not to materially alter the general character of the cross-section of the bar as a Whole. The bars 7 terminate in spindles ,8, 8, whereby they may be mounted across the tie beams 6 to freely rotate about their longitudinal axes. In the present embodiment of my invention one of the spindles (8) is mounted in a bearing 9 bolted to the top flange of a tie-beam 6 adjacent to one side of the beam, the spindle 8' at the opposite end of the bar being received in a socket a of a casting 10 secured to the flange of the tiebeam by a jaw formation 10, the said casting resting on the portion of the tie-beam not occupied by the bearings 9, and being formed with a recess w for receiving the series of bearings 9 supporting the spindles 8 of an adjacent set of alining bars. The tie beams (with the exception of the terminal members) thus serve to support the bearings 9 carrying the terminal spindles 8 of one set of bars, and also the castings 10 carrying the spindles 8' of an adjacent alining set of bars. In practice I provide a bearing 9 for each bar, but a single casting 10 is formed with a plurality of sockets a to accommodate the spindles of a number of bars. In the present example there are four castings (Fig. 2) disposed the length of a tie-beam, each casting accommodating six spindles. These details may of course be changed by the skilled mechanic, the important feature being the rotatable character of the grate-bars. For reasons to presently appear, the center of gravity of the grate-bar should be considerably below its rotation axis and to accomplish this object in the simplest manner I provide each bar with a centraldownwardly projecting arm 11 disposed at right angles to the bar, said arm terminating in a weight 12 to insure the lowerin or removal of the center of gravity of tiie bar below its rotation axis as far as possible. A bar so weighted when left freely suspended in its bearings will dispose itself normally, that is to say with its top 7 in a horizontal plane, and with the weight. 12 directly below said top, it being understood that the arm 11 is perpendicular to the plane of the grate-bar top, the longitudinal axis of the arm bisecting the angle formed by the sloping sides h of the bar.

The operation may best be described by a reference to Figs. 4, 5, 8 and 10. When the pan is in its normal or upright position, all the grate-bars have their tops or ridges 1' disposed in the same horizontal plane above the plane of their axes of rotation, the arms 11 carrying the Weights hanging vertical (Figs. 4, 8). The bars being freely suspended, it follows that they will remain disposed with the arms 11 hanging vertical so long as their freedom of rotation is not interfered with or arrested. This arrest takes place when the weight of the end bar strikes the inner face of the wall of the pan on the dumping side with a tilt of the pan through an angle of substantially thirty degrees more or less (Fig. 10), the weights of the successive bars bearing against one another, the weight of one bar supporting the weight of the bar adjacent thereto. The bars and their weights remain in this position until the pan is fully inverted (Fig. 5), the same resuming their normal positions under the action of gravity when the pan'is subsequently righted after the sinter or material undergoing treatment has been discharged. The effect on the bars when the pan is tilted from its normal position (Fig. 4), to the inclined position shown in Fig. 10, is the same as if the pan were to remain in its upright or normal position and the bars were rocked about their rotation axes through a corresponding angle (thirty degrees, more or less). That effect is shown by the dotted positions of the bars in Fig. 8, it being obvious that the edge e of one bar will sweep downward while the adjacent edge e of a contiguous bar will sweep upward. In other words, the face h of a bar on one side of a slot 8 will sweep downward, while the face it of a bar on the opposite side of a slot 8 sweeps upward. This will cause a separation of the opposed faces (t) forming the boundaries of the normal slot 8 and also rock the ridges or tops 1' away from the horizontal plane along which they are normally disposed to collectively form an even surface of support for the charge (Fig. 3'). This normal horizontal surface of support accordingly undergoes a distortion the moment the pan is started in its tilting movement, the limit of the distortion being reached by the time the weighted arms 11 are arrested in their relative sweep toward the descending wall on the dumping side of the pan (Fig; 10).. The effect of this relative rotary motion of the grate-bars (the pan being the member actually rotated and the bars remaining stationary with their weighted arms vertically suspended) upon the charge supported thereby is to cause the sloping face lb of one bar to lift and at the same time slide over the bottom surface of the charge contacting with said face, while the opposing face it of the contiguous bar drops away from said bottom surface of the charge, thereby causing a break or weakening of the body of the material composing the charge through a shifting or disturbance of its otherwise normal and uniform support, this relative sweep of the opposing faces h, h, in opposite directions exercising a shearing effect on the sinter, all of which tends to break the sinter and loosen the same from the bars; and by the time the pan is fully inverted the sintered charge readily drops from the bars, leaving the bars and the spaces between them clean and ready to receive the next'charge of ore. In Fig. 5, the loosened material is shown dropping off the bars, Fig. 10 in a general way showing the distortion suffered by the bottom surface of the charge with a dumping movement of the pan. The shearing and breaking effect on the material is of course at its maximum when every bar is mounted rotatably in its bearings. It would however be fully within the spirit of my invention to have every other bar rotatable and the others rigid or non-rotatable. Thus, in Fig. 11 are shown diagrammatically rotatable bars 7 and nonrotatable bars 7 the latter being provided with square supporting stems 8" in lieu of r the cylindrical spindles 8, 8, carried by the rotatable bars 7 The shearing and breaking effect on the sintered material would obviously be reduced one-half in the modified construction, but with some ores it might answer the purpose very well. In the modification shown in Fig. 11, the stationary bars 7." are obviously not provided with weighted arms, but in other respects are the same in construction as the bars 7, corresponding parts being identified by the same reference letters or symbols. It is to be understood of course that I am not to be restricted to the particular cross-section of grate-bar herein shown, the bar in the drawings being merely by way ofexample.

Having described my invention what I claim is:

1. A grate-bar rotatable about its longitudinal axis, and having its center of gravity below said axis.

2. A grate-bar comprising a member elongated in one direction and terminating in means for supporting the same rotatably about its longitudinal axis, the same being weighted to bring its center of gravity below said axis when freely suspended.

3. In combination with a treatment vessel tiltable to dumping position about a fixed axis, a grate for supporting the charge to be treated comprising a succession of individual parallel bars spaced apart, said bars being freely rotatable about their longitudinal axes, and means for causing the adjacentedges of-contiguous bars to participate in a separating movement with a dumping movement of the vessel for dislodging the material resting on the bars.

4. In combination with a sintering pan rotable about a fixed axis for purposes of dumping, a grate for supporting the charge comprising a succession of parallel bars spaced apart and freely rotatable about their longitudinal axes,'and means for causing bars, the upper edges of said sides terminat ing insupporting ridges disposed in a plane removed a suitable distance from the spaces between the bars.

6. In combination with a treatment vessel rotatable in a given plane for dumping, a grate comprising a-succession of freely suspended rotary bars having their centers of gravity below their axes of rotation, and positioned to maintain their normally suspended positions during the sweep of the pan through a given arc.

7, In combination with a treatment vessel rotatable in a given plane for dumping, a succession of grate-bars freely rotatable about their longitudinal axes disposed parallel to the rotation axis of the pan and spaced apart, and formed. with opposing side faces sloping toward the spaces between the bars, suitable means on the bars for bringing their centers of gravity" below the rotation axes thereof, whereby in the tilting of the vessel for dumping, the bars will have imparted thereto a relative rotary movement causing the opposing sloping faces of contiguous bars to sweep in opposite directions for dislodging or shearing the material supported thereby.

8. In combination with a sinterin pan rotatable'about a fixed'axis for dumplng, a grate comprising a succession of bars spaced apartand disposed parallel to the rotation axis of the pan, the bars being mounted rotatably about their longitudinal axes and weighted to bring their centers of gravity below said axes, the tops of the bars collectively forming a normal supporting surface for the charge, said surface suffering distortion with a dumping movement of the pan and the consequent relative rotary displacement of the grate-bars.

9. A grate comprising a series of rotary bars weighted tobring their centers of gravity below the rotationaxes of the bars, each bar being formed with a top supporting ridge, and sides diverging downwardly from said ridge toward the spaces separating the bars. 10. A grate comprising a succession of parallel bars spaced apart, all or a portion of said bars being mounted to freely rotate about their longitudinal axes, the rotatable bars being weighted to bring their centers of gravity below the rotation axes thereof.

elongated in one direction and terminating in means for supporting the same rotatably about its longitudinal axis, and a weighted arm projecting from the bar at an angle to said axis to bring the center of gravity of the bar below its rotation axis when freely suspended.

12. A grate-bar comprising a member elongated in one direction and provided with a top, and side faces diverging therefrom in oppositedirections, means on the bar for suspending the same rotatably about its longitudinal axis, an arm projecting from the bottom of the bar, the axis of the arm bisecting the angle formed by the diverging side faces aforesaid, and a terminal weight on said arm.

13. In combination with a sintering pan rotatable about a fixed axis for dumplng, a grate comprising a,plurality of bars spaced apart and disposed parallel to said axis, the bars being suspended to freely rotate about their longitudinal axes, arms depending from said bars, weights terminating the free ends of the arms, the .wall of the pan adj acent the first bar of the series operating to arrest said bar in its relative rotary displacement by the arrest of the weight of said bar with a tiltin of' the pan through a given arc, the weig ts of successive bars arresting the weights of the bars adjacent thereto, whereby all the bars undergo a retary displacement to the same degree.

14. In combination with a treatment vessel rotatable about a fixed axis for dumping, a grate comprising a succession of parallel bars spaced apart and rotatable about their longitudinal axes, the bars collectively forming a supporting surface for the charge, and means for imparting to the bars a relative rotary displacement with a dumping movement of the vessel and thereby distorting the supporting surface normally formed by the bars.

15. In combination with a treatment vessel rotatable about a fixed axis for dumping, a grate comprising a succession of bars spaced apart and rotatable about axes disposed parallel to the rotation axis of the vessel, and means for automatically imparting to the bars a relative rotary displacement with a dumping movement of the vessel.

In testimony whereof I aflix my signature, in presence of two witnesses.

- JOHN E. GREENAWALT. Witnesses:

KATHERINE SoUDnER,

MAE E. UNGAnLEmER.

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