US2254323A - Sintering machine - Google Patents

Description

p 3941 E. w. SHALLOCK 2,254,323

SINTER ING MACHINE Filed July 5, 1940 4 Sheets-Sheet 1 INVENTOR. ZZZzz/a/d KM hczlzock BY 5 fl 1 5W1 raw/Aw ATTORNEYS.

P 2, 1941- E. w. SHALLOCK 2,254,323

SINTERING MACHINE Filed July 5, 1940 4 Sheets-Sheet 2 I N VE NTOR.

FCZtZ/G/ZZ Z0. Shallow? BY m 1!- ram ATTORNEYS.

2, 19410 E. w. SHALLOCK SINTERING MACHINE 4-Sheets-Sheen 3 Filed July 5, 1940 INVENTOR. Eda/card 2W. Shea Z l 0 0145 ATTORNEYS. Z

E. w. SHALLOCK SINTERING MACHINE Filed July 5, 1940. 4 Sheets-Sheet 4 INVENTOR. Edward M'J/aa 6100/:

Patented Sept. 2 1941 I SINTERIN G MACHINE Edward W. Shallock, Chicago, Ill., assignor to American Ore Reclamation Company, Chicagm. Ill., a corporation of New York Application July 5, 1940, Serial No. 344,000 1 Claim. (01.266-21) This invention relates to the sintering of ores, flue dust and other materials preliminary to further treatment thereof, and has to do with a machine for effecting the sintering operation.

In a sintering plant in which a continuous type of sintering machine is used the breaking up of the sinter bed at its point of discharge and'subsequent falling onto a screen creates clouds of dust, smoke and heat. It is known to place a hood over the discharge area of the machine, this hood having one or more stacks to carry away to atmosphere the dust, smoke and heat, by the natural draft created in the stack. While this eliminates to a considerable extent dust in the building of the sintering plant, it distributes this a dust over the surrounding territory which, particularly in congested areas, is a nuisance and a menace to health. Also, the dust frequently has same value which, under the present practice referred to, is lost. The instant invention is'.directed to avoiding the above noted objections to the present practice by utilizing the air flow employed in the operation of the sintering machine in a novel manner.

In the operation of a sintering machine atmospheric air is drawn through the sinter bed, that is the bed of material to be sintered, in large. volume during the sintering process. I have found that by placing a hood structure over the sinter bed and about the discharge end or area of the sintering machine, it is possible to cause air in considerable volume and at considerable velocity to flow through this structure from the discharge area of the machine, this air flow sufiicing to entrain the fine particles and dust and smoke liberated in the discharge of the sinter and to convey such products to the surface of a portion of the sinter bed undergoing combustion. The air continues to flow through the sinter bed for supporting combustion therein and the bed serves as a screen effective for trapping the dust and fine particles of material which are thus retained in the sinter bed in large portion so as to form a part of the sinter. Any fine dust particles which may pass through the sinter bed will go to themain dust collecting system of the plant and will not escape to atmosphere. In that manner the means for causing flow of air through the bed of material for sintering it-also serves to collect the dust and smoke at the discharge area of the machine and to conduct such material to the sinter bed. Also, the air passing at considerable velocity and in considerable volume over the dis-v charged sinter serves to abstract a considerable sinter and also materially raising the temperature of the air which is thus preheated by the discharged sinter before passing through the sinter bed. This preheated air promotes combustion in the sinter bed and renders feasible the use therein of a smaller proportion of combustible ingredients than would otherwise be possible, thus effecting a material saving in that respect while also expediting the sintering operation and correspond-' Figure 2 is a sectional view taken substantiallyon line 2-2 of Figure 1;

Figure 3 is a fragmentary sectional view, on an enlarged scale, similar to Figure 2;

Figure 4 is a fragmentary sectional view, on an enlarged scale, taken substantially on line 4-4 of Figure 1, certain parts being omitted for clearness of illustration;

Figure 5 is a sectional view taken substantially on line 5-5 of Figure 4;

Figure 6 is a sectional view, on an enlarged scale, taken substantially on line 66 of Figure 3;

Figure '7 is' a fragmentary vertical sectional view taken through one side of the hood structure and the adjacent side wall of a pallet, showing a modified form of construction;

Figure 8 is a view similar to Figure 4, showing a modified form of closure means at the inner end of the hood Figure 9 is a sectional view taken substantially on line 9-9 of Figure 8;

Figure 10 is a fragmentary vertical sectional view of the hood and a pallet, atone side thereof, showing a second modified form of closure means therebetween; and

Figure 11 is a view similar to Figure 10, showing a third modified form of closure means between the hood and the pallet.

I have illustrated my invention, by way of example, as embodied in a continuous sintering machine of the Dwight and Lloyd type. The

construction and operation of this typ of sintering machine are well known in the art and a brief description thereof will suffice. The sintering machine is shown, in Figure 1, as mounted portion of the heat therefrom, thus cooling the on a suitable platform or floor l0 and comprises a suitable frame carrying an endless track ll comprising an upper horizontal run and a lower run upon which travel a train of pallets l2. At the feed end of the machine the pallets are raised, by known means, from the lower run of the track about the retiun bend to the upper run. Each of these pallets carries a suitable grate l3 and the pallets on the upper run of the track are in endwise contact providing a continuous traveling grate structure,- the pallets being wheel mounted for travel on the track as is known. At the feed end of the machine the pallets are charged with the material to be sintered, by means of a charging chute ll or equivalent means, thus providing a bed l5 of material to be sintered supported by the grate structure and traveling therewith. The pallets'are propelled along the upper run of the track from the feed end of the machine and toward the other end thereof, which for purposes of description may be referred to as the forward or discharge end of the machine. After leaving the charging device it the pallets pass beneath an igniter l3,

of known type, by means of which the top of the bed of material I5 is ignited. During the remainder of the travel of the pallets along the top run of the track, they pass over suction boxes I! connected by conduits l8 to a manifold l9 which is connected to the intake of a suction fan 20 of suitable type and capacity. The outlet of fan 20 is connected to a conduit 2| which goes to a stack which may discharge into the atmosphere. If desired, a suitable dust collecting system, of known type, may be inserted between conduit l9 and fan 20, as is known in the art.

At the other end of the machine the pallets pass about a return bend by means of which they are conveyed to the lower run of track II. In passing about this return bend the pallets serve successively to break the sinter on the grates thereof from the remainder of the sinter bed, and this sinter is discharged onto an inclined plate 22 by which the sinter is directed downward and forward onto a screen 23 formed of grizzly bars. During travel of the pallets over the suction boxes ll, air in large volume is drawn downward through the bed of material causing down draft combustion therein from the top to the bottom of the bed, so that the bed of material has been completely sintered by the time it reaches the discharge end of the machine, as is known in the art.

As'the sinter is discharged at the forward or they enter upon the forward return bend of the track. That creates clouds of considerable quantities of fine particles and dust and smoke, while liberating considerable heat from the hot sinter. In order to prevent entry of this dust and heat and smoke into the space within the building of the plant, it is the present practice to provide a hood about the discharge end of the machine, this hood having stacks which discharge into the atmosphere, as previously noted. That is objectionable for the reasons stated. I

I have found that it is practicable to prevent escape into the building of the sintering plant of the smoke, dust and heat occurring at the discharge area or end of the machine while also recovering the major portion at least'of the dust and fine particles of material liberated and utilizing to advantage heat abstracted from the discharged hot sinter. I accomplishthat by causing air, in considerable volume andconsiderable velocity, to flow over and about'the discharged sinter and thenceto the sinter bed on;

the pallets and through'this-bed, thuscollecting and conveying to the sinter bed the smokeand r dust and finer particles of materials liberated by breaking of the sinter, while also abstracting i j from the hot sinter ,a considerable portion of'its heat, thus preheating the air which, in passing through the sinter'bed, expedites the sintering operation. This I accomplish by the means which is provided for causing flow'of air through the sinter bed for promoting and sustaining combustion therein, which is conducive to efilciency and simplicity in construction and operation.

In applying my invention to the machine illustrated I provide a hood structure 24, conveniently formed of bowed frame members 23 extending tures 25 support sheet metal elements 28 extending therebetween and secured thereto, the

members 25 and 23 together constituting a hood extending over the forward portion of the upper run of the machine. is suitably secured to and opens into the rearward end of a casing 21, conveniently formed of sheet metal and suitably reinforced, if required. Casing 21 comprises a downwardly and forwardly tapering upper portion 28 and 9. depending portion constituting a bin 29, below plate 22 and screen 23. This bin is provided with a discharge spout 30 normally closed by a valve 3| of suitable type. Portion 28 of casing 21 extends downward beyond the lower end of screen 23, with its lower wall constituting an extension of chute 3i leading from the screen and open at its lower end at 32. The casing 21 is air tight or substantially so, such that air entering this casing will, in major portion at least, enter through the opening 32.

The pallets l2 and the suction boxes l8 are provided with sealing means 33, of known type,

for effecting a substantially air tight seal therebetween at each side ofthe pallets. This sealing means is known in the art and requires no detail description here. Suflice it to state that suitable means is provided for effecting substantially air tight seals between the pallets and the suction boxes.-

Means is provided for effecting substantially air tight seals between the side walls of the hood 24 and the sides of the pallets. To that end, angle strips 34 are suitably secured, as by spot welding or in any other suitable mannento the side walls of hood 24, adjacent the lower edges thereof and between the frame 25. Sealing strips 35, formed of asbestos composition or any other suitable heat and abrasive resistant material, are secured to the under faces of the lower flanges of angle strips 34, by bolt and nut means 38. These sealas shown in Figure 6, and these strips are suit ably notched from their outer edges, at 38, to accommodate the frame 25. Sealing plates 39,

At its forward end hood 24 from plate 4!.

fitted about the frame 25 and secured thereto by flanges 40, are disposed to underlie the notches 38 in contact with strips 35 to substantially close the portions of notches 38 extending inward beyond frame members 25. The sealing strips 35 and associated parts thus cooperate with the side walls of the pallets l2 so as to provide substantially air tight closures along the sides of the hood.

The major portion of the inner or rearward end of the hood 24 is closed by an end closure plate M. A plate 42 is hinged at its upper edge, adjacent each end, at 43, to the lower edge of plate 4|. The lower portion of plate 42 is shaped to 'fit into the upper portion of a pallet, with its lower' edge resting upon the upper face of the material I5 which, when it reaches the plate 42 is undergoing combustion and constitutes the sinter bed. This plate 42 is disposed for turning movement in the direction of travel of the sinter bed, as indicated in Figure 5, and is held in contact with the top surface of the bed by gravity. The plates 4| and 42 thus provide, in conjunction with the pallets and the sinter bed, means for excluding air from the inner end of the hood. It will be obvious that there will be slight openings into the hood at the inner end thereof and at the.

sides, due to the necessity for providing mechanical clearances. The amount of air entering the hood through these openings, however, will be relatively quite small and will not adversely affect the operation of the hood and associated parts member 50 may be of a width to extend downward into the pal1et, with suitable clearances, notches for accommodating the side walls of the pallet being, of course, then unnecessary. That is a variation which will be clear from the foregoing and requires no illustration. In general, the member for efiecting a closure at the inner end of the hood may be of any suitable form and extent, within the broader teaching of my invention.

The modified closure means between each side of hood 24 and the pallets l2, shown in Figure 10,

comprises a member 53 depending from element in the intended manner. 'In that connection it may be noted that the suction adjacent and exterior of the inner end of the hood is effective for preventing entry of any considerable amount of air into the hood through this end.

In the modified form of sealing means shown in Figure '7, the side walls of hood 24a are shortened slightly, so that the sealing strips a engage beneath outwardly extending shoulders l2b at the top of the side walls of pallets l2a, the sealing strips also, if desired, extending into contact with the side walls of the pallets. In the operation of the machine .the suction created within hood 24 serves to hold the sealing strips 35a in sealing contact with the under faces of shoulders l2b, thus guarding against 'air leakage into the hood at that point. In other respects the construction shown in Figure 7 is similar to that shown in Figures 1 to 6, inclusive,,and requires no further description. Any other suitable means foreifecting substantially air tight seals between the sides of the hood and the sides of the pallets passing therethrough may be provided, and two further forms of such means will be referred to presently, by way of example.

The modified closure means at the inner end of the hood, shown in Figure 8, comprises a member 50, in the form of a plate or curtain, depending Member 56 may be secured to plate 4| in any suitable manner, as by means of a Z-strip 5| riveted to plate 41 and to member 56. The latter extends downward into pallet l2, with slight clearance between the lower edge of member 50 and the top of the sinter bed I5, clearance also being provided between the sides of the pallet and the sides of member 56. As shown in Figure 8, member 50 is equal in width to pallet l2 and is notched out at each side, to extend across the side wall of the pallet with slight clearance there. Member 50 may be formed of asbestos or analogous heat resistant material, sheet metal, or of any other suitable material. Instead of extending the full width of the pallet,'as shown,

or member 26 of the hood, withits lower portion disposed to contact the outer face of shoulder I 20 of the pallet. Member 53, which may be formed of asbestos or other suitable heat and abrasive resistant material, is secured to member 26 in any suitable manner, as by being bolted thereto. Preferably, member 53 possesses appreciable flexibility while having sufiicient rigidity to assure sealing contact between the lower portion of this member and the outer face of shoulder I20. In the operation of the machine, the partial vacuum or suction within hood 24 causes members 53, at opposite sides of the hood, to be held by atmospheric pressure in sealing contact with shoulders 120 of the pallets I2. If desired, member 53 may be formed of sheet metal and slight clearance be-' tween this member and the outer faces of the shoulders of the pallets may be provided for, or member 53 may be hinged, in a known manner, to hood member 26 so as to be movable into sealing contact with the pallets, as will readily be understood. Under ordinary conditions, however, I prefer to form member 53 of a suitable heat and abrasive resistant material, such as asbestos or an analogous material-or composition.

The modification shown in Figure 11 is similar to that shown in Figure 10, except that closure member 53a is formed of sheet metal and overlies the upper face of shoulder ,l2c of pallet l2, with slight clearance between the lower edge of member 53a and the shoulder. If desired, member 53a may be formed of asbestos or any other suitable material.

There are various places in a sintering plant, in addition to the sintering machine itself, where dust arises, such as the mixers where the material to be sintered is mixed, the bins at which material is discharged onto a belt to be conveyed to the mixer, etc. Entry of that dust into the space within the building of the plant is objectionable for obvious reasons. I find that it is possible to take care of the dust areas referred to in a simple and efficient manner by providing a hood at such respective areas and connecting this hood by a conduit 45 to the hood and casing structure 24-21 of the sintering machine. In Figure 1 I have shown a conduit 45 opening into bin 29, below screen 23. This conduit is provided with appropriate valve means, shown as a damper 46 of conventional type, for controlling 'air flow therethrough. When damper 46 is opened, either partially or completely, air will be drawn through conduit 45 thus creating air flow in. the hood connected to the other end of this conduit, effective for entraining dust and sinter bed is also utilized for collecting dust from dust areas remote from the sintering machine and conveying this dust to the sinter bed. While I have shown but one conduit 45, by way of example, it will be understood that any suitable number of conduits may be provided leading to different dust areas, each controlled by a valve 46. The fan 20, is, of course, of proper type and capacity to handle the required volume of air and to assure flow of air in considerable volume and at considerable velocity into casing 21, through opening 32 thereof, even when the valves 46 of the conduits 45 are open. By adjusting valve 46 of conduit 45, or the valves of additional conduits, if provided, the flow of air through opening 32 may be regulated within limits, as desired.

In the operation of the machine the combustible' ingredients contained in the sinter bed have been consumed by the time the sinter bed reaches the discharge end of the machine, or substantially so. Accordingly, no further combustion of the discharged sinter occurs, though this sinter is discharged at a comparatively high temperature. Breakage of the sinter as it is discharged, and during its passage downward over plate 22 and screen 23 creates clouds of dust and smoke and fine particles of the material, as above explained. As the sinter passes downward along the screen 23 and the bottom wall of lower portion 3| of casing 21, it encounters the air passing into the casing through opening 32, at high velocity and in considerable volume. This air extracts from the hot sinter a considerable portion of the apparent heat thereof and also serves to entrain the smoke, dust and fine particles of material and to convey them to the sinter bed, which traps such materials, in major portion at least. Air entering casing 21 through conduit 45, below screen 23, passes upward and supplements the action of the main volume of air entering casing 21 by opening 32, to entrain the dust and fine particles of material in the manner stated. It will be seen that the sinter is cooled to a considerable extent by the air flowing thereover and is also cleaned by removal therefrom of considerable dust and fine particles of material which otherwise would be discharged with the sinter. That is advantageous in providing relatively clean sinter and also has the advantage that the sinter is cooled to a considerable extent and may be more readily handled to advantage. The sinter fines which pass through the screen 23 and are not entrained by the air fiowing through the casing 21 are collected in the bin 29, from which they may at times be removed, as required'and in any suitable manner, and conveyed to the mixer to be included in a succeeding batch of material to be sintered.

In the operation of the machine the material to be sintered is disposed in a bed which is ignitedat one side or surface, after which air is caused to flow through the bed from that surface so as to cause combustion interiorly of the bed and thereby sinter it, the means for causing fiow of air through the bed being effective for collecting dust at a dust area, such as the discharge point of the sintering machine, and conveying this dust to the sinter bed at the surface thereof from which combustion is initiated, so that the dust is trapped by the sinter bed and incorporated in the sinter. The advantages of that with respect to eliminating dust nuisance in a sintering plant, while also recovering the dust which in many instances contains values and expediting combustion, thus increasing the production of the sintering machine or apparatus, are obvious and need not be set forth in detail. Specifically my invention is particularly suitable for use in sintering machines of the continuous type, such as that herein illustrated, but in its broader aspects my invention may be used with any type of sintering machine or apparatus to which it is applicable.

' I claim:

In a continuous sintering machine, conveyor means for supporting a traveling bed of material to be sintered and discharging the sinter at the forward end of the machine, suction-box means beneath said conveyor means for inducing down draft through the bed of material, a sinter screen inclined downward from said forward end and disposed to receive on its upper face the discharged sinter, a casing enclosing said screen extending thereabove and having an opening adjacent the lower end of and above said screen aligned therewith for discharge of sinter therefrom and entry of air into said casing, said casing comprising a sinter fines bin extending beneath said screen and normally closed to the atmosphere, said screen being efiective for separating the fines and smaller pieces of sinter from the larger pieces, the fines and. smaller pieces of sinter passing through said screen into said bin and the larger pieces of sinter being directed by said screen to and through said opening at the lower end of said screen, a hood opening at its forward end into the rearward end of the upper portion of said casing extending rearward from the latter over a portion of said conveyor means and a portion of said suction-box means and extending a considerable distance above said conveyor means for free fiow of gases within said hood above the sinter bed, the portion of said conveyor means extending rearward from said hood being open to the atmosphere for free flow of air thereto, sealing means providing substantially air tight closures between said conveyor means and said hood at the sides of the latter, and means at the rearward end of said hood providing a substantially air tight closure therefor.

EDWARD W. SHALLOCK.

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