US2624560A - Shaft furnace - Google Patents

Description

Jan. 6, 1953 J. J. CRAIG EI'AL 2,624,560

SHAFT FURNACE Filed Jan. 18, 1949 8 Sheets-Sheet l INVENTORS Jw/v J C'RA/G JOSEP/I f. OUNAsA y BY Mum f. MmGA/v Am Lou/s E0644 1953 J. J. CRAIG ET AL 2,624,560

SHAFT FURNACE Filed Jan. 18, 1949 8 Sheets-Sheet 3 I VIII/III! IN VEN TORS :JOH/Y J. CRAIG JbSEPH f. Dwmsxy BY M4 TON 5 MOEGA/Y 40am laws F0 LL 34W Arron/vex? Jan. 6, 1953 J. J. CRAIG EI'AL SHAFT FURNACE Filed Jan. 18, 1949 8 Sheets-Sheet 4 IN V EN TOR5 W msm N Amws m @005 w A ip M NNN Jan. 6, 1953 J. J. CRAIG ETAL SHAFT FURNACE 8 Sheets-Sheet 6 Filed Jan. 18, 1949 IN VEN TORS Jw/v J 67mm; JOSEP/l E Ouxwsxry BY Mun/v E Ma es/1N SHAFT FURNACE 8 Sheets-Sheet '7 Filed Jan. 18, 1949 1N VEN T 0R5 Jo/l/v f CRAIG fosa w .-0u/-/As/(y M4 ro/y E MORGAN A0040 1011/5 F 'ELL M07, 20%,

ArroR EX- W Da u Q Q 3 Q MQ 8v K? m 9 mm mm mm 8 Ex symmetrical pellets.

Patented Jan. 6, 1953 UNIT ED OFFICE SHAFT FURNACE Delaware ApplicationJanuaryB, 1949, Serial No. 71,512

11 Claims. I.

This invention relatesto shaft furnaces and more particularly, to a novel construction of the grates and discharging mechanism for such' afurnacewhich, while not limited thereto, is especially useful for heating pellets of line particle, metalliferous material.

In. certain metallurgical processes. it is often necessary, to crush metalliferous materials to substantially finel particle size inorder to remove the. gangue therefrom. Sinceit is. usually desirable to obtain metalliferous material in. suitable sizes-for practical utilization, the relatively'finesized materialmust be agglomerated.

Byway ofexample, but without limitation thereby, attention is directedto the fact that the rapid. depletion of high-grade iron ore deposits;

intheMesabiRange has caused increasing inter.- est to be directedto both itslower-grade ores: and iron-bearing rocks, there being immense deposits of each. One of these rocks, taconite, is available in enormous quantities and. while taconite is not practical as a charge for a blastfurnace, it may be conditioned through the removal of a per centage of its gangue to so-increasethe percentage of: iron, as iron oxide, and through agglomera-- tion thereafter, so as1t0 becommerciallyaccept-- able. as a burden for conventional blast furnaces.

The above-mentioned and other. metalliferous materials of fine particle size,,afterconcentration;

have. been agglomerated into bodies of suitablesize'by compacting the=particlesinto substantially This may be effected'by a procedure suchas disclosed by Firth, in Patent No, 2,411,873; which, produces substantially balllike bodies, or by other known procedures. thepurposeof simplicity, fine particles of metalliferous material which have been agglomerated into larger bodies by balling or other known procedures will: behereinafter referredto: as. pellets,

it being, understood that this term: isused; in: a. generic'sense; and-is not intended to be limitedto. substantially spherical agglomerates formedfrom iron ore concentrates by the procedure'dis' closed-by Firth butv is: intended to. include. allegglomerates formed from fine: particles of metal? liferous. material;

Pellets.- as formedbythe'Firth andother known procedures are generally somewhat moist: and

upon drying. are relatively fragile but may be sufficiently, hardened, lay-heating to permithandling thereof by conventional ore-handlingequip ment. 'Ihisheating of the pellets-should bersub stantially uniform toeffect the desireddegree-rof; hardeninglin all the'pelletsbut must not Ice such; as; to cause incipient: fusion. resulting; in. the:

formation of large clusters of the pellets. More.-

over, since thepellets are, relatively fragilebefore.

they have been heated, they mustnot be subjected. to forces resultin in substantial breakage or abrasion duringthe heating. Whilebatch pro:- ceduresrmaybe employed, the productionofpellets; is rendered more. economically. feasible; through the use of continuous methods.

lhe principal; object of thisinvention. is therefore,.the provision-of animproved shaft furnace. which isso; constructed andarranged that it will.

satisfactorily effect heating of pellets, formed; fromfine. particles of metalliferous. material, whichiaresubstantially continuously charged into the. top andremoved from the bottom of. menunace wherebythe'heating isv effected. as a. continuous operation without breaking ofv the pellets. or-the formation of excessively large clusters,

Another, object of: the invention is. to,v provide. an: improvedshaft. furnace in which. the. move.-- ment. of theburden therethrough is accurately, controlled andthe burden is discharged substantially-w-ithout crushing. I

A-further: object. of the invention is to. provide 2.11. improved shaft furnace for hardening pellets. offinemetalliferous material, the gratesand dis? chargemechanism of the furnace being so; constructed; and:- arranged. that the pellets in any horizontal plane move downwardly through. the. furnace at a.-. substantially uniform. rate, and the pellets. may be subjected to sufficient agitation..- adjacent. the, gratebars, to break up any large. clustersrof pellets-that. may form thereby faciliitating; discharge from the furnace.

A further object of the invention is the provision of aeshaft furnace of the. type. mentioned in the-preceding objectand wherein the grate bars.

thereof are individually supported elongated.

tionedand wherein the rate of. movementofthe;

burden through the furnace. is controlled by. a. pluralityof;spaced,.substantially. horizontally dis..- posed plates extending transversely of. the run-- nacebelow the openings between the. grate bars, the said plates being. repeatedly moved. to dis-- 'charge a. predetermined portion of. theburden.

resting thereon in a manner such. that. the. in.

' div-idual pellets of the burden in any horizontal planeawithin-the=furnace move downwardly at a. substantially uniform, rate- A more specific object of the invention is the..

provision of a shaft furnace for hardening pellets of iron ore concentrates or the like, by heating, which furnace has a plurality of spaced, inverted substantially V-shaped grate bars extending transversely of the shaft of the furnace adjacent the bottom thereof and supported for limited movement relative to the shell of the furnace, there also being a plurality of substantially horizontally disposed plates extending transversely of the furnace below the openings between the grate bars, the said plates being reciprocated in a manner to discharge a portion of the pellets resting thereon with the extents of movement of the several plates being so regulated that the pellets in any horizontal plane within the furnace move downwardly at a substantially uniform rate.

The invention further resides in certain novel features of construction and combination and arrangement of parts, and further objects and advantages thereof will be apparent to those skilled in the art to which it pertains from the fOllOWil'lg description of the present preferred embodiment, and a modification of a portion thereof, described with reference to the accompanying drawings in which similar reference characters represent corresponding parts in the several views and in which:

Fig. 1 is a view, partly in front elevation and partly in vertical section, of a furnace constructed in accordance with this invention with certain parts omitted and others broken away;

Fig. 2 is a side view, partly in section and partly in side elevation of the furnace illustrated in Fig. l, the view being taken from the right-hand side of Fig. l with certain parts broken away and others omitted;

Fig. 3 is a transverse sectional view taken substantially on the section indicating line 33 of Fig. l and locking in the direction indicated by the arrows, the view being to an enlarged scale with respect to Fig. l with portions intermediate the end walls of the furnace broken away;

Fig. l is a sectional View taken substantially on the section indicating line 44 of Fig. 3 and looking in the direction indicated by the arrows, portions being broken away and the grate bars and associated inclined plates being indicated in broken lines;

Fig. 5 is a fragmentary sectional view to an enlarged scale showing the manner in which the rollers for supporting the discharge plates are mounted, the section being taken substantially on the section indicating line 55 of Figs. 4 and 6;

Fig. 6 is a fragmentary elevational view to an enlarged scale of the eccentric mounting for the end of a roller as seen from the right-hand side of Fig. 5;

Fig. '7 is a fragmentary sectional view to an enlarged scale of the grate bars, inclined plates, and discharge plates illustrated in Fig. 1;

Fig. 8 is an enlarged sectional view illustrating the manner in which the grate bars are supported and the present preferred means for vibrating these bars, the view being taken substantially on line 8-8 of Fig.7;

Fig. 9 is an enlarged fragmentary rear elevational view of the mechanism associated with the bottom of the furnace to control the delivery of the material therefrom;

Fig. 10 is a sectional view taken substantially on the section indicating line I 0|0 of Fig. 9 and looking in the direction indicated by the arrows;

Fig. 11 is a fragmentary sectional view taken substantially on the section indicating line i l! l of Fig. 10 and looking in the direction indicated by the arrows;

Fig. 12 is a fragmentary sectional view taken substantially on the section indicating line lZ-lZ of Fig. 10 and looking in the direction indicated by the arrows;

Fig. 13 is an enlarged detached View, partly in section and partly in plan, illustrating one of the pivoted valves for controlling the discharge of material, the associated inclined plate being omitted;

Fig. 14 is an enlarged fragmentary view, partly in side elevation and partly in section, the view being taken substantially on the line l i-i of Fig. 3 and illustrating the operative connections for reciprocating the sliding discharge plates;

Fig. 15 is a fragmentary view, partially in plan and partially in section, illustrating another means for vibrating the grate bars;

Fig. 16 is an enlarged sectional view taken substantially on the section indicating line i6i6 of Fig. 15 and looking in the directions indicated by the arrows; and

Fig. 1'7 is a schematic showing of the cam means for vibrating the grate bars in the manner shown in Figs. 15 and 16 and illustrating the relative positions of the several cams at a given time.

It will be appreciated that the furnace of this invention may be utilized for operations other than hardening pellets of metalliferous material by heating but because its novel construction renders it especially useful for this purpose the description will, for simplicity, be restricted to such a use. It is to be understood, however, that this restriction is only for the purpose of clarity and is not to be considered as a limitation of the invention.

Referring now in detail to the drawings, it will be seen that the invention is embodied in a shaft furnace, designated generally 20, which is preferably of rectangular cross section. The furnace comprises a shell 2| formed of steel plates suitably secured together and reinforced by channel members 22, the furnace being supported at the desired elevation by vertically extending standards or legs 23, 24, 25 and 26. As will be seen from Figs. 1 and 2, the upper portion of the shell 2| is provided with a suitably refractory type lining 21 thereby forming the shaft proper of the furnace, a portion of the shell 2| extending inwardly beneath the lining 2'! to retain the latter in place. Suitable reinforcements are provided beneath the lining by channel members such as 23 which form a rectangular frame secured to the tops of the aforementioned legs 23, 24, 25 and 26.

The shell 2| is continued downwardly below the lining 21, substantially in alignment with the inner surface of the latter, and this portion of the shell is provided with grate bars and reciprocating discharge plates. The lower part of this portion of the shell merges into two downwardly converging hopper-shaped portions 29 and 3D constituting a plenum and discharge chambers for the furnace. The lower portions of the hopper- like portions 29, 30 respectively converge to, and communicate with, vertically extending discharge conduits or spouts 3| and 32 through which the material from the shaft furnace is discharged to, and removed by, a conveyor 33. As will be hereinafter described, the discharge of material is controlled by the novel grate bars and discharge plates, intermediate the shaft and the 5 plenum of the furnace, acting in conjunction with gas sealing valves in the discharge spouts.

As shown in Figs 1, 2, 7 and 8, the grate bars 34 extend transversely of the furnace shaft, ad-

jacent the bottom thereof, in parallel spaced relationship and are supported from the shell of the furnace in a manner such that they may receive limited movement or vibrations without transmission of such vibrations to the lining of the furnace. These grate bars 34 are preferably shaped substantially as shown in the drawings from which it will be seen that the bars are substantially inverted V-shaped in cross section and have integral closed ends such as 35, see Fig. 8. The two end bars, however, are only half the width of the other bars, these end bars each having one inclined side thereof omitted to provide perpendicular surfaces for cooperation with the adjacent side walls of the furnace and thereby prevent the lodging of material between these bars and the side walls. The grate bars are preferably formed of cast metal and all but the two end bars are provided with two vertically-spaced pipes, such as 36 and 31, which extend longitudinally through the bars and are preferably embedded therein at the time the bars are cast. While the pipes have been shown, the members 36 and 31 may be shafts or bars. For simplicity, however, only the term pipe will be used hereinafter in referring to the members 36 and 31.

Each pipe 36 extends through the integral, solid apex of its grate bar and is provided with a collar or flange 38 adjacent either end of the bar and embedded within the material of the latter to prevent longitudinal displacement of the pipe with respect thereto. The pipe 31 extends parallel with, but vertically spaced below the pipe 36, and is likewise provided with a collar r flange such as 39, adjacent either end of the grate bar, which collars are embedded within the closed end walls 35 of the latter to securely retain the pipe 31 and prevent its longitudinal displacement relative to the grate bar. These pipes provide a means for imparting vibrations to the grate bars as will hereinafter appear.

Each grate bar is supported by hangers connected with the shell of the furnace and engaging the grate bars adjacent their ends. As shown most clearly in Figs. 7 and 8, these hangers each comprise a plate 40 having an aperture therethrough substantially the same shape as that of the grate bar 34 but slightly larger so that the grate bar may extend freely therethrough. The bottoms of the end walls 35 of the grate bars 34 are each provided with a transversely extending notch or recess 4i, and each notch or recess 4| is adapted to fit over the lower edge of the opening in the corresponding hanger plate 46 sothat the-grate bars are suspended by the hanger plates 40 and may move therewith.

Each hanger plate 40 is supported, adjacent its upper edge, from a longitudinally extending flange of a channel member, such as 23, by pairs of spaced links, there being two pairs of such links for each plate 40 except those which support the two end bars. This is effected by employing a pair of spaced eye bolts such as 42, 43 for each plate 49 which supports one of the intermediate grate bars, the shanks of which bolts pass through the lower flange of the channel member 28 and are secured thereto by suitable nuts 44. The eye of each of the bolts, such as 42 and 43, extends between the upper ends of one pair of links such as 45, 46 and the latter are supported'by a pin '47 extending therethrough port the intermediate bars.

and through the eye of the bolt. The lower ends of the links 45 and 46 extend downwardly below the upper edge of the corresponding plate 40, on either side thereof, and spaced therefrom, and are provided with a transversely extending pin 48 which passes through a hole in the plate 40, this hole preferably being of larger diameter than the pin. It will be seen that the relative dimensions of the eye bolts and of the plates 40 are such that the links 45, 46 straddle the upper por tions of the plates 40 with a clearance so that the plates 40 may move relative to links such as 45, 46 in directions extending parallel with the grate bars 34, the link construction, however, preventing any substantial vibrations from being transmitted to the furnace lining '21. Since there are two eye bolts and two pairs of spaced links for each hanger plate 40 of each intermediate grate bar, the grate bars are maintained parallel with each other at all times.

The two half or end grate bars are shown as supported at either end by a single eye bolt and pair of spaced links since their hanger plates are but half the width of the plates 48 which sup- These half or end bars are not vibrated and hence are not provided with spaced pipes such as 36, 31. Since the two end bars are not vibrated, they may be rigidly supported in the furnace, if desired.

Each of the channel members 28, to which the eye bolts are connected, has a shield member 49 secured to its lower flange. These shields are angular in cross section and each has a downwardly directed portion which extends substantially parallel with, but spaced inwardly from, the supporting links for the grate bars so that the material within the furnace cannot enter into the spaces between the links and interfere with the vibration of the grate bars.

The pipes such as 36 and 31, which are united with each of the grate bars 34, other than the two end bars, extend outwardly therefrom beyond the side walls of the furnace through suitable openings in the shell of the latter, suitable packing or sealing means being provided to prevent the escape of gases at these points while permitting longitudinal movement of the pipes. For this purpose, the shell of the furnace is provided with the plates, such as 50, which 'cover the openings in the shell of the furnace through which the grate bars are initially inserted, these plates 50 being provided with holes therethrough for accommodating the pipes 36 and 31. Surrounding each pipe 33, 31, and the holes therefor through the plates 56, is an annular member 51 which is secured to the plate 50 by a flanged ring 52. Each annular member 5| has a sleevelike portion spaced outwardly from the pipe which extends therethrough thereby providing an annular chamber about the pipe in which chamber packing material 53 is disposed. This packing material is retained in place by a sleeve-like portion of a gland member 54 which is slidably fitted within the outer end of the member 5|, the members 5| and 54 being secured together by bolts such as 55 which extend through out* wardly directed flanges of the members.

The grate bars 34 may be vibrated by any suitable means which will impart relatively high frequency, short stroke, movement thereto. This vibration of the grate bars tends to break up any relatively large clusters that may form without, however, effecting an appreciable grinding action upon the material passing between the grate bars. One suitablemeansfor effecting vibration is illustrated in Figs. 1, 2, and 8 as comprising electromagnetic vibrators, generally designated 55, there being one such vibrator attached to the adjacent ends of each pair of pipes 36 and 3! externally of the shell of the furnace. These vibrators are of well-known cons 'uction and hence need not be illustrated or described in detail but may be briefly characterized by mentioning each contains coil springs disposed within housings 5?, 58 and cooperating with a suitable inertia member within a housing 59, the inertia member being actuated by an electromagnet to thereby impart vibration to the pipes 36, 3? and hence to the corresponding grate bar 34.

Preferably, the vibrators for alternate grate bars are arranged on opposite sides of the furnace as shown in Fig. 2, these vibrators being capable of individual or simultaneous actuation so that one or any desired number of the grate bars may be vibrated. It should be particularly noted that the vibration thus imparted. to the grate bars is of exceedingly short stroke and therefore is not equivalent to the usual transverse movement of grate bars for discharging material therebetween. It should also be noted that adjacent grate bars are vibrated in a manner to move them in opposite directions relative to each other.

Instead of individual electromagnetic vibrators for vibrating the grate bars other mechanisms may be employed for imparting the desired vibratory motion. For example, there illustrated in Figs. 15, 16 and 17 a somewhat diagrammatic representation of a mechanism for effecting relatively short-stroke movement of the grate bars simultaneously in opposite directions by means of a single electric motor. In this construction the adjacent ends of the pipes 3? of each of the movable grate bars are joined together as by welding to separate plates such as Gil. These plates are bolted or otherwise adjustably secured to flanges of members El which have spaced outwardly extending portions or ears, a shim or shims 62 being placed between the members Gt and 6! to provide for an adjustment of the members 6| relative to the actuating mechanism about to be described. The ear portions of each member ti are pivotally connected to a link 53 which extends therebetween and outwardly therefrom, the outer ends of the links being provided with enlarged. cir cular bosses G4. Extending through the central openings of the several bosses 64 is a common drive shaft 65 which is mounted in suitable bearings such as supported by structural iron members 8'! which are in turn connected with the legs or with reinforcing portions of the furnace The shaft 35 is disposed eccentrically within the openings of the bosses Bi and the shaft is surrounded by and keyed or otherwise connected with disk or collar-like members 88 rotatably fitted within the openings of each of the enlarged bosses G6. The collars or disks E8, in effect, provide cams upon the shaft 5e and are so positioned that the lobes of adjacent cams extend in diametrically opposite directions. This will be apparent from the schematic representation in l? which illustrates the relative anguiar positions of the disks or collars forming the cam lobes.

The shaft 65 is rotated by a motor 69 through a change-speed mechanism 76), the motor and change-speed mechanisms being suitably mountplates is and 7?.

ed upon the furnace supports by mean not shown. It will be apparent, therefore, that when the motor 69 is rotated, the resulting rotation of the shaft 65, and of the attached disks or cams, results in movement of the grate bars, adjacent grate bars moving in opposite directions with respect to each other. As in the preferred form of vibrating mechanism, the length of stroke of the grate bars in this movement is relatively short, the length of the stroke resulting from the mechanism shown in Figs. 16 and 17 being, however, greater than that resulting from the use of electromagnetic vibrators such as shown in Fig. 8. Also, while the frequency of the movement of the grate bars is relatively low the motion is vibratory in nature and hence reference hereinafter and in the subioined claims to vibration of the grate bars is intended to cover the mechanism illustrated in Figs. 15, 16 and 17 unless excluded by recitation of features not present therein.

A discharge controlling mechanism is supported in spaced relationship below the grate bars and moves in a substantially horizontal direction for controlling the discharge of the material from the shaft of the furnace. This mechanism comprises a plurality of plate-like members, equal in number to the number of spaces between the grate bars, and mounted to extend transversely of the furnace substantially below the said spaces between the grate bars, the plates being movable transversely of the grate bars in a manner hereinafter described. The lower surfaces of these plate members are each supported adjacent their ends upon longitudinally extending bars H which are in turn supported upon rollers such as 72 extending transversely of the furnace and rotatably supported from the side Walls thereof, see Figs. 4 and 5. The intermediate discharge plate members, such as T3, T4, and 75, that is all but the two end plates of the discharge mechanism, are welded to the previously mentioned bars Tl while the two end plates 76 and 11 are not welded to the bars II but are slidable thereon.

The intermediate plates, such as 13, 14, and 15, are each provided with a downwardly extending, substantially centrally located bar 18, 79, and 80, respectively, extending between the bars H and secured to the latter and to the corresponding plates i4, i5 as by welding. The end plates 76 and l? are provided with similar downwardly extending bars 8| and 82, respectively, which are welded to the lower surface of the The ends of these bars 15 and i'i are not welded to the bar 2'! but instead are welded to separate bars such as 83, 84 which extend parallel with, and spaced slightly inwardly from the bars 7!, these bars 83 and 84 having their upper edges welded to the corresponding plates '16 and i2, as will be seen from Figs. 3 and 4.

Inclined plates, such as 85, are mounted below and at one side of the spaces between the grate bars 3%. These plates are substantially parallel, extend transversely of the furnace, and have their ends secured to the hanger plates 4i! for the adjacent grate bars. The upper edges of these plates 85 are adjacent the lower right-hand portions of the grate bars, as seen in Figs. 1, 4 and 7 and the lower edges of these inclined plates are disposed slightly above the upper surfaces of the reciprocating plates, such as T3 to T1, and adjacent the left-hand edges thereof when the plates are in the positions shown in the drawings. Consequently, the pellets or other material 9? falling between the: grate-bars. 34 are guided by the plates 85 onto the reciprocating plates I3 and 11, the dimensions of the parts being such that the angle of repose of the material, with the mechanism positioned as shown in the drawings, causes the material to be retained upon the horizontal discharge plates such as 13 to 11. When the latter plates are moved to the left, as viewed in the drawings, a layer of. the pellets or other material supported thereon is caused to move outwardly over the right-hand edges of these plates due to the relative motion between the latter and the inclined plates 85, the material thus discharged dropping downward into the funnel-shaped portions 29, 30 of the furnace and being discharged therefrom as hereinafter described. In view of the tendency of the side walls of the furnace to partially support the material therein, which tendency is especially noticeable adjacent the end walls probably due to the transverse arrangement of the grates, the end plates I6 and I! are preferably moved greater distances than are the intermediate plates, such as It, I4 and I5, during each stroke. of the plates. As shown in Figs. 3 and 4, the downwardly extending bar SI, which is connected with the plate It, is connected substantially centrally thereof to a pipe or rod 86. This pipe or rod slidably extends through the downwardly extending member 88 of plate I5 and slidably through a larger diameter pipe or tube 81 which is connected to one or more of the downwardly extending bars, such as I9, of the intermediate discharge plates F3 to I5. The tube or pipe 8'! in turn is slidably passed through a third pipe or tube 88 which is connected to the downwardly extending bar 82 secured to the plate 7?. These pipes or tubes extend through the side wall of the furnace, which is provided at this point with a substantial stuffing box or sealing gland, generally designated 89, which may be simillar to the previously described sealing means provided for the outwardly extending tubes of the grate bars and which is illustrated in detail in Fi 8.

The outer surface of the pipe 8% is threaded adjacent its end, see Fig. 14, and an internally threaded sleeve s9 is screwed thereon and retained in adjusted position by-a set screw, or the like BI. The forward end portion of the sleeve 9!? is of reduced diameter and is provided with an external screw thread on which is screwed a collar 92 which is retained in adjusted position by a set screw or the like 93. The sleeve 95 has an upstanding flange portion providing an integral shoulder and between the shoulder and the external threaded portion is a cylindrical surface 94 on which a yoke member 215 is slidably positioned. The inner face of the collar e2 provides a second abutment for this yoke. member and the extent of its sliding movement upon the cylindrical surface 9 is adjustable by varying the position of the collar $2.

The tube 8i extends outwardly beyond the outer end of the tube 38 and a gas seal 98 is provided on the outer end of the latter tube for cooperation with the former. This gas seal may be of any suitable construction, but is here shownas sleeve member threaded upon the end of the tube and having an inwardly directed flange between which and the outer end of the tube as is provided a suitable packing material 9?.

The tube 81 is threaded adjacent its outer end and is provided with a sleeve member 98 adjustably secured in position bya set screw or the like 99, these partsbeing substantially identical with those provided upon the tube 83 and designated 90, 9|, respectively. The sleeve 98 is likewise provided with an adjustable collar II!!! which. is held in adjusted position by a set screw, or the like, it)! thereby providing an adjustable abutment for a yoke member I92 which is slidable between the integral flange portion of the sleeve member 95 and the collar Iilil in a similar manner to the previously'described yoke member 95. The outer'end of the tube 8? is likewise provided with agas seal or packing gland I03 coperating with the outer surface of the tube or rod 85 in. the same manner that the seal 96 cooperates with the tube 81.

The outer extending end of the tube or rod 86 is likewise screw-threaded and provided with a sleeve and collar organization I94, I85 for receiving therebetween a third yoke member I06, the sleeve I94 and the collar I65 being'held in adjusted positions by set, screws ill! and I83 as in the previously-described similar organizations attached to the tubes 88 and 81. If the member 86 be a tube, as shown, the. outer, end thereof may be provided with a suitable cap or plug to prevent the escape of gases therethrough. Preferably, however, this sealing is effected by a plug or cap I09 provided upon the inner end of the tube, as shown in Fig. 4.

The yoke members 95, I62, and I06 are connected together and maintained in predetermined spaced relationship by a pair of spaced rods Hi] and I I! passing through apertured ends of'the yoke members and provided with tubular spacers H2, intermediate the yoke members, to maintain predetermined distances between the latter; the ends of the rods being threaded and provided with suitable nuts H3, see Fig. 3. Se cured to the upper and lower surfaces, respectively, of the yoke member Hi6 are pairs of spaced, forwardly-extending plate members H4 and I i5, the forward ends of the plates I I4 being connected to the corresponding plates M5 by spaced blocks IIG and II 1. A lever H8 has an intermediate portion positioned between the blocks lit and II? and is pivotally connected with the blocks by'a pivot pin or shaft II9, the ends of which are supported in the spacer blocks. The lower end of the lever H8 is pivotally supported between spaced bracket members I 29 which are secured to a portion of a framework extending between the legs of the furnace. The upper end of the lever H8 is bifurcated and the bifurcation thereof is pro vided with a connection member lZI which is pivoted on a pin. I22 mounted eccentrically upon the output shaft of a gear reduction unit 323 driven by an electric motor I24; The motor I24 and gear reduction unit I23 are adjustably supported upon a platform, generally designated I25, which is attached to the legs of the furnace. Connected with apart of the supports for this platform and the brackets I25 is an upstanding guide plate I26 which has semi-circular recesses in its upper edge in which the spacer tubes II2 of the yoke mechanism are received thereby guiding and supporting the latter in its reciprocating movements.

The construction just described is such that, when the motor I24 is energized, the lever-I I8 is rocked about its pivotal support in the brackets I26 thereby imparting reciprocating movement to the discharge plates, such as'I3 to 11, through the yoke members 95, I02, and H16 which, it will be remembered, are connected together by the 11 rods I I6 and I I I. The resulting extents of movements of the end plates I6 and 11 relative to the intermediate plates, such as I3, M and I5, is determined by the adjustments of the collar members, such as 92, IIIII, I which are capable of providing a desired amount of lost motion between the correpsonding yoke members and the tubes actuated thereby. For example, as shown in Fig. 14, the collar I85 is so positioned that it holds the yoke member I05 firmly against the integral flange on the sleeve member I04 so there is no lost motion at this point. Consequently, the tube 86 and the plate 76 connected therewith are reciprocated the maximum extent by the movement of the lever I I8. The collar I90 is, however,

position in spaced relationship to the integral flange of the sleeve member 93 so that the yoke member I02 has a lost motion between the collar and the flange of the sleeve and, consequently, the tube 81 has a stroke of lesser length than that of the tube 86 due to this lost motion travel of the yoke I52 between the sleeve and collar members. Therefore, the intermediate plates, such as I3, I4 and I5, move together butt through a lesser distance than the end plate IS. The intermediate plate I3, I4 and I5 all move as a unit since it will be remembered that they are each connected to the bar members II which are in turn connected to the bar member IS with which the tube 81 is connected. The collar 92 is shown as positioned to provide a lost motion for the yoke member 95 between the collar and the flange of the sleeve member 9!), this lost motion, however, being less than that of the yoke member I 02. Consequently, the tube 88, and hence the plate 1! which is connected therewith, is reciprocated through a distance which is greater than that of the intermediate plates but less than that of the end plate I6.

The amount of adjustment of the collars, such as 92, I00, and I05, here shown is to be understood as illustrative only since the extents of movements of the several plates may be varied as is necessary or desired in accordance with the characteristics of the material in the furnace, the extents of movements of the discharge plates being selected to provide a substantially uniform discharge of the material for the entire cross sectional area of the shaft of the furnace. That is to say, the plates, such as I3 to II, should be given reciprocating movements of such extent that the material in any horizontal layer through the shaft of the furnace moves substantially uniformly downwardly as the plates are reciprocated.

The rollers, such as I2, which support the discharge plate mechanism preferably comprise pipes or tubes I2'I which extend substantially the entire width of the furnace and are rotatably supported upon shafts 01 rods I28, the ends of the latter extending through the side walls of the furnace and being adjustably mounted therein. As shown in Figs. 5 and 6, this adjustable mounting is effected by providing bearing members I 29 for the ends of the shafts, each of which bearing members has the opening for the shaft I28 eccentrically disposed. The bearing members I29 each have an outwardly extending flange portion provided with a plurality of spaced notches I30 by which the bearing members may be rotated thereby changing the elevation of the shafts I28 and the tubes I2! to provide the desired elevation and alignment of the bars II of the discharge mechanism. When the bearing members I29 have been properly positioned, they may be se- 12 cured in this position by inserting a lug-like member I3I into one of the notches and welding the latter t the side wall of the furnace. While the members I29 have been described as bearing members, it will be understood that the shafts I 28 do not rotate therein during the reciproca tion of the grate .bars, but instead the tubes or pipes I2'I rotate with respect thereto. Consequently, the ends of the shafts or rods I28 are secured by means of lock washers I32 and nuts I33, the latter being secured upon the threaded outer ends of the shafts.

The bars II, and hence the discharge plates, are laterally guided and constrained to straight line motion by means of rollers I 34, see Fig. 3. These rollers have their axes disposed vertically and are supported upon opposite side walls of the furnace by brackets I 35 in positions such that the rollers engage the outer sides of the bars II and are at all times shielded by the discharge plate IS.

It will be understood that the furnace is operated under pressure. That is to say, gas such as air, gaseous fuel, or mixtures thereof will be introduced into the plenum of the furnace below the grate bars and ascend therebetween and through openings such as I35 in the grate bars to effect heating of the pellets or other burden in the furnace. Therefore, each hopper-like portion 29, 3!! of the plenum is provided with an inlet Opening I37 to which a suitable conduit is attached for conducting such gas or gases into the furnace. Consequently, the discharge of material from the furnace must be effected through a gas seal to prevent interference with the pressure conditions in the furnace and prevent loss of the gas or gases. To effect the discharge and provide such a gas seal each discharge spout or conduit 3|, 32 of the furnace is provided with valve mechanisms operated in timed relationship with the reciprocation of the discharge plates, such as I3 to 11.

As will be seen from Figs. 1 and 9 of the drawings, the discharge valves are provided in vertically spaced pairs in each conduit, the upper valves in each conduit operating together and sequentially with respect to the lower valve in each conduit, which likewise operate together. As illustrated in Figs. 9 and 10, the conduit 3! is provided, intermediate its top and bottom, with an inclined plate I38 which is permanently attached to a portion of the side wall of the conduit and extends at an angle downwardly therein, the lower edge of the plate terminating short of the portion of the conduit side wall which is diametrically opposite the top of the plate so that the latter extends approximately two-thirds of the way across the conduit. The inclination of the plate is such that its highest portion is adjacent that side of the conduit which receives the impact of the majority of the pellets moving downwardly therein; that is to say, the relative position of the inclined plate with respect to the discharge plates, such as I3 to II, should preferably be as shown in Fig. 1.

The opening through the conduit between the lower edge of the inclined plate I38 and the adjacent portion of the conduit side wall is adapted to be opened and closed by a pivoted valve I39. The details of this valve are shown to an enlarged scale in Fig. 13 from which it will be seen that the valve comprises a substantially semicircular plate-like member having spaced integral or rigidly attached bosses I 40, I4! provided along the chordal portion which corresponds with its rear edge. These bosses have-openings therethrough to receive a mounting; shaft I42 which is journalled in bearings I43 and I 14 provided atdiametrically opposite points in the side wall of the conduit 3!, to the rear and adjacent the lower edge of the incline plate I38, The openings through the bosses I 35), I iI are somewhat larger than the e ernal diameter of the shaft I 12 so that the valve plate I39 is freely pivoted upon the shaft and may partake of some radial movement with respect thereto. Intermediate the bosses I40, I the shaft I42 has a collar member i415 attached thereto by any suitable means and this collar has spaced arms Hi8 and I l! which extend forwardly under the valve plate 39 with upwardly extending projections which engage the under surface of the latter The shaft :42 extends beyond the bearings M3, I44 and is provided at one end with a. retaining collar I68, the other end of the shaft being provided with an actuating arm I49 which is attached to the, shaft M2 in any suitable manner to sheet movement of the latter by rocking of the former.

Vertically spaced below the inclined plate I133 and valve I39, the conduit SI is provided with a second permanently secured inclined plate I55 similar to the plate I38 but extending in the. opposite direction so that its lower edge, which is spaced from the side wall of the conduit, is beheath" the portion of the plate I33 which is attached to the conduit, see Figs. 1 and 9. Beneath the plate I58 and cooperating therewith, to selectively open and close the space between the conduitand the lower edge of. the plate, is a pivoted valve BEI. manner as is the valve 39. but is oppositely disposed within the conduit. The valve IEI issupportedin a similar manner to the valve E39 and is actuated by an arm I52.

The conduit 32 is provided with an upper rigidly mounted inclined plate I53 and cooperating pivoted valve I54 corresponding in construction and position with the plate I38 and valve I39, the valve- I515 being provided with an actuating arm I55 for effecting movement thereof. Vertically spaced below the plate I55 and valve I54, the conduit 32 is provided with a second inclined plate I and pivoted valve i5 which are constructed in the same manner as the previously described plates and valves and are mounted in the same horizontal plane and the same relative'positions as the inclined plate It?) and valve iEI' in the conduit 3|. The valve I 5'! is provided with an actuating arm E53 corresponding with previously-- mentioned actuating arms, such as I49, I52 and The actuating mechanism for the discharge valves is supported ina suitable framework, which is here shown as comprising a pair of spaced channel members I59 and Ito which extend horizontally between the hopper- like portions 29, 39 of the furnace plenum on opposite sides of the downwardly extending conduits or pipes 3!, 32. Intermediate the conduits, the channels I59 and I60 are each provided with a downward extending channel member I'fiI and 262, respectively, the lower ends of which are connected together by a transversely extending member I63. Supported upon this framework are the actuators, generally designated I64 and M5, for operating the lower valves IEiI, I51! and the upper valves I39, I54, respectively.

These actuators are identical and are of the type well known to the trade as a Thrustor and henceneed not be described in detail. Suffice it This valve is constructed in the same "[4 to note that such. a device essentially comprises a hydraulic. cylinder I66 in which fluid pressure is developed by an electric motor I61 so that. a piston in the cylinder is moved therethrough. to efiect a thrust upon a pair of spaced rods lfid and I69 connected to the'pi'ston, the upper ends of the rods being'joined by a cross member no. As is well known, when'the motor Id! of such a: deviceis energized, the cross member I'IIl ismoved relatively slowly outwardly with respect tov the cylinder andsattains its extremeposition after a time interval of several seconds, this position. being maintained-so long as the. motor is energized. Upon deenergizati'on. of; the motor, the rodsv I68 and- I69, together with the cross member I15), return. to their" initial position, the time interval of this movement being substantially the same as that required for their outward movement.

The actuator I64 has its cross member I?!) conneotedto a composite lever I'II formed by a pair of spaced bars connected together" as" is shown lIl' FiES. 1o, 11', andl2, the member I'I'El being pivotally connected to the lever" inter' mediate the ends of: the latter. One: end of the lever I?! isconnected to a' sleeve I12 which is rotatably supported upon a shaft H3 extend ing transversely: between. the channel members Ihi, I82; the other end; of the level. being prorv-ided; with a' pivotally mounted counterweight H4. The sleeve H2 is provided, adjacentthe inner face: of the channel IS! with a pair of spaced arms I15, HE which. are connected to rock with the sleeve I'='I2'.. The outer ends of the arms I15. and. IE5 have a downwardly extending link I'Ii received: therebetween; the-uppcrend of the link: being. pivotally connected with the arms I; I76. The lower end of" the link- IT! is received'between, and pivoted to, the outer ends" of a pair of" spaced arms I73. and H9 of a compositebell crank lever, designated generally as I86. This lever is fixed, intermediate its end to: a sleeve I'8I which: is-rockable upon a shaft I82 extending transversely between and mounted in the channel. membersi- IsiI: and. IE2. The second pairofspaced. arms 53 and ltd: of the. bell crank lever Ii'lii straddle and are pivotaily connected to'adiacent ends of substantially hori' zonta-lly extending links. I and: IE3 the outer ends of which are connected, respectively, with the actuating" arms. i5 2 and Idfii for the valves II- and I5 1.

As shown in- 9 and 10, the outer end of the. linl: its is adiustably connected with" a clevis IS? which straddles the arm I52 is pivoted thereto, adjustment. being: effected by a threaded portioniupon the rod I35 engaging in threaded opening of the clevis I 81 with the parts being maintained in adjusted position-by jam or lockinut IE8. outer end of the linl-r: Idfi is. likewise screw-threaded but this threaded end does not thread'ahly the cievi's. I89. which is pivotally connected to rock arm IE8. Instead, the outer end of the link; I35 slidably extends through an opening in the clevis, the outer end of the link Hit-being provided with a nut I98 which is adapted to engage the portion. of" the clevis adjacent-' the opening therethroughwhen a pull isexerted. on the link; I88; interposed between the end of the clevis I39 and a nut Id-Iv upon the inner thrcaded'portion ofthe link It? is'a' compression spring IQE'thecompression of. which may be ad justedby adjustment of. thenut F82. There is thus provided a yieldable-connecticn in the. actuating mechanism for the. valvesv I51, I51: to

prevent injury to the parts if a pellet should be lodged between the end of one of the valve plates and the side wall of a conduit such as 3|, 32 when the valves are operated to closed position.

The mechanism just described operates, when the motor I61 is energized, to rock the lever I'II in a clockwise direction, as viewed in Fig. 9. This rocks the arms I15, I16 moving the link I11 downwardly thereby rocking the bell crank lever I80 in a clockwise direction so that the links I85, I86 are moved to the left actuating the valves I5I, I51 to open position. When the motor I61 is deenergized the counterweight I14 returns the actuating mechanism to its initial position. That is, the lever I1I is now rocked counter-clockwise, thus elevating the link I11 and rocking the bell crank lever I89 in a counterclockwise direction so that the links I85, I85 move to the right, as viewed in Figs. 9 and 10, thereby closing the valves I5I and I51. In the event a pellet or other particle should have lodged between the edge of one or both of the valves I 5I, I 51, the actuating mechanism may return to its initial position without effecting undue strains thereon or damage to the parts. This is due, in part, to the fact that the spring I92 provides a yieldable connection between the actuating mechanism and the valve plates. Moreover, it will be remembered that the valves are not directly moved by the actuating arms I 52, I 58 but freely rest upon the members or arms, such as I46, I41, which are connected to move with the arms I52, I58. It will also be remembered that there is radial play between the shaft and the bearing bosses of each of the valve plates. Consequently, the valve plates I5! and I51 may be displaced sufiiciently to clear an obstruction such as a pellet, or a fragment thereof, and then continue to its closed position under the action of the spring I 90 which is compressed if such an obstruction is encountered during the closing operation.

The actuator I65 is connected for operation of the valves I39 and I 54 in. a somewhat similar manner to that just described for the connection of the actuator I64 to the valves I 5| and I51. Thus, the cross member I93 of the actuator I65, which corresponds with the member I10 of the actuator I64, is pivotally connected to a composite lever I94 intermediate the ends of the latter. One end of the lever I94 is connected to a sleeve I95, which is rockably mounted on the shaft I13, the other end of the lever I94 being pivotally connected to a counterweight I96. The sleeve I95 has the ends of a pair of spaced arms I91, I98 fixed thereto, the arms extending downwardly therefrom with their lower ends straddling and pivotally connected to substantially horizontally extending links I99 and 200. These links are connected with the rock arms I49 and I55 for the valves I39 and I54, respectively, by means of clevises providing adjustable and yieldable connections, as previously described with respect to the links I85 and I86, so that the valves I 39 and I54 operate in substantially the same manner as the valves I5I, I51. Therefore, when the actuator I65 has its motor I energized, the lever I94 is rocked in a counter-clockwise direction, as viewed in Fig. 9, thus moving the valves I 39 and I54 to open positions. Likewise, deenergization of the motor 20I causes the counterweight I96 to rock the lever I94 back to its initial position thereby closing the valves I39, I54, this being effected without damage to the parts even though a particle or particles might have temporarily lodged adjacent their edges.

As mentioned heretofore, the discharge valves operate in timed relationship with the actuation of the discharge plates, such as 13 to 11. This is accomplished by controlling the energization of the motors I51, 20I by means of cam-actuated switches contained within a housing identified in the drawings as a Timer which is mounted upon the gear reduction unit I23 so that the camactuated switches are operated by the output shaft of the unit. The electric circuit thus controlled may be conventional and hence is not illustrated in detail. Sufice it to note that the cam switches are so disposed that both motors I61 and 28I are deenergized when the discharge plates 12 to 11 are positioned as shown in the drawings. As the motor moves these plates in a direction to discharge a portion of the material thereon, i. e., to the left as viewed in Figs. 1, 3 and 4, the motor I61 is energized thus opening the valves I5! and I51. Near the end of the stroke of the discharge plates in this direction the motor I61 is deenergized so that the valves I5I and I51 are again closed. Durin the return stroke of the discharge plates, the motor 23I is energized thus opening the valves I39 and I54. By the time the discharge plates have returned to their initial positions the motor 2M is deenergized so that the valves I39 and I54 are again closed.

For example, when the discharge plates require an interval of approximately twenty-two seconds for one complete reciprocation, all the valves I39, I5I, I54 and I51 are closed during the initial two seconds of the movement of the discharge plates in direction which effects displacement of agglomerates or other material thereon. At the end of this interval of two seconds, the motor I6! is energized and during the next two seconds of operation the discharge plates are further moved in the direction for effecting discharge of the agglomerates and the lower valve plates I5I, I51 move to open positions and remain open during the following three seconds of the cycle, thus allowing discharge of any material that may be present between the valve plates I39, I 5| and I54, I51, respectively. During the next two seconds of discharging movement of the plates, such as 13 to 11, the motor I61 is deenergized and the valves I5I, I51 move to closed positions, approximately two seconds being required for this operation. All of the valves then remain closed for the remaining two seconds of the discharging movement of the plates 13 to 11.

During the above-mentioned eleven seconds of operation of the plates 13 to 11 in the discharging direction, the pellets or other material discharged thereby will have dropped into the conduits 3I, 32 and come to rest upon the valve plates I 39 and I54 so that a gas seal is maintained while the lower valves I5I and I51 are open. In the initial two seconds of the interval of return movement of the plates 13 to 11, all valves remain closed and thereafter the motor 29I is energized. Hence, the valves I39, I54 move to open positions during the next two seconds and remain open for three additional seconds due to the continued energization of the motor 29I The pellets or other material that have accumulated above the valves I39 and I54 drop into the space between these valves and the lower valves I5I and I51 while further discharge of material is being gradually reduced by the return movement of the discharge plates 13 to 11. During the next succeeding two secends of this. return movement, the motor 28E is deenergized so that. the valve plates I39 and I54 return to closed positions and remain closed dur ing the final two seconds required to complete the return stroke of the discharge plates which terminates further fall of material into the conduits 3t. 32.

This cycle is then repeated so that the pellets that have accumulated between the upper and lower valves in the conduits 3|, 32 are discharged as a new quantity of the pellets drops from the discharge plates onto the upper valves I39, I53. Consequently, an effective gas seal is maintained so that free communication of the plenum of the furnace through the discharge conduits 3|, 32 is never possible, these openings being sealed at all times by one or more of the valves together with the agglomerates accumulating thereon. It is to be understood that the time intervals just given are by way of illustration only and are not intended as a limitation, since the time cycle may be varied for any given furnace in accordance with the type of material treated therein, the operating characteristics of the furnace, and the like, and moreover, the length of time interval will vary in accordance with the size of the furnace. Furthermore, the energization of the motors Nil, 281 may, if desired, be controlled by a suitable timing or sequencing device not actuated from the gear reduction unit I23. For example, a suitable clockwork mechanism or the like may be employed to effect the sequential energization and deenergization.

The pellets discharged from the lower ends of the conduits 3|, 32 pass into a hood 202 which is connected with the lower ends of the conduits and is further supported by the channel members I6 I, 462 and the transverse member H53. "This hood extends closely adjacent the previously-mentioned conveyor 33 which carries the discharged pellets to a point of further treatment or utilization, the hood being provided as a means towithdraw and prevent the spread of dust or the like at this point.

Therefore, the hood 202 has one end closed, as

indicated in 2&3, and adjacent the other end is provided with a transversely extending pivoted wall or flap 2%, the pivoted wall or flap being disposed adjacent that end of the hood through which the discharge particles move upon the conveyor 33. Intermediate the wall '20! and pivoted flap 292, and between the conduits 3!, 32, are provided one or more additional pivoted walls or flaps. In the present construction two such additional pivoted walls or flaps 295 and 2E6 are shown, these being illustrated as provided at the lower ends of relatively rigid upper wall portions 26'! and 298, respectively. The pivoted walls or flaps allow the free passage of the pellets or other particles upon the conveyor, butsubstantially prevent the passage of dust or the like resulting from the impact of the pellets upon the conveyor 33 when the'valves II, I51 are initially opened.

In order to remove dust from the hood, the latter is provided with exhaust pipes or stacks 289, 2 lfl'which communicate with the hood intermediate the walls or, flaps 264, 295 and 203, 2%, respectively. These exhaust conduits or stacks are connected with a suitable exhaust and dust collecting means, not shown, to which is also connected the hood 2 I I provided at the upper end of the shaft of the furnace. Preferably a sight opening 2 I2 is provided in one or more of the side walls of the lower hood 222 intermediate the pivoted walls or flaps 205,.23t to enable the operator to determine if pellets or other particles are 18 being discharged fromtheconduit 32, which may be determined by the presence of such pellets or particles moving along the belt 33 towards the wall 205.

Proper heating of pellets, or similar particles, is greatly facilitated by charging the pellets, or the like, into the shaft of the furnace in substantially uniform layers. Therefore, the top of the furnace is provided with a pair of spaced rails 2I3, 2M extending transversely with respect to the grate bars and discharge plates. These rails serve to support and guide a movable conveyor, designated generally 2| 5, which is adapted to move across the top of the furnace and deposit the pellets or other particles therein, the width of the conveyor 2 I5 being substantially equal to the width of the shaft of the furnace. In order to accom 'modate the conveyor 2 I5, the hood 2 I I is shown as having an opening 2I5 atone side thereof. This opening may be partially closed, if desired, by a pivoted wall or the like, not shown, which would extend closely adjacent the top of the conveyor and yet allow movement of the latter therethrough, such a wall or flap being similar to the wall or flap 204. To facilitate access to the furnace, a portion of the hood 2 II adjacent the opening 2'I6 may be hinged, as indicated at 251, and in addition suitable access openings, such as 2 I 8', may be provided.

Access to the plenum of the furnace, for cleaning or repair operations is afforded by manhole openings provided with suitable covers, such as 2I9, as is well known in the art.- In addition,

.the opposite side walls of the furnace shell are provided. with pokehole openings, such as 22!! adjacent the upper edges of the grate bars and intermediate the latter. These latter openings are normally closed by suitable plugs which may be removed for the insertion of a poker or the like if at any time it be necessary to break up clusters or remove obstructions from between the grate bars.

It is believed that the operation of a shaft furnace constructed as described will be apparent from the above detailed description of the several parts thereof. However, in order to facilitate an understanding, the operation may be briefly summarized as follows:

The furnace is charged by employing the conveyor 2I5 tolay down successive layers of green pellets within the shaft of the furnace. Since these pellets may contain a certain amount of solid fuel therein, they may be satisfactorily heated by simply introducing heated air through the openings, such as I31, which air ascends between the grate bars and through the openings [36 therein to effect combustion of the solid fuel in the pellets thereby heating the latter to the desired temperature. If, however, solid fuel be not employed, in the pellets, or if solid fuel .be thus used but in less quantity than the amount necessary to provide the desired heat, a gaseous fuel may be introduced along with the air through the openings I31, or through separate openings, the fuel burning between and amongv the pellets to heat, or assist in heating, the latter. The operation of the furnace is so controlled that the highest temperature zone therein is preferably within the shaft of the furnace and above the grate bars. Consequently, the incoming air and/or other gas passing over the lowermost pellets, whichare below the highest temperature zone, cool these pellets while the ascending hot gases above the combustion zone tend to dry and preheat the green pellets moving downwardly within the furnace-from the top thereof. It will be understood that the lower pellets which have been heated to the desired extent and are then somewhat cooled by the ascending gases will rest upon and between the grate bars 34, a portion of the pellets moving downwardly therebetween and coming to rest upon the upper surface of the discharge plates 13 to TI which have sufficient width to extend beyond the pellets thereon when the latter have reached their angle of repose.

Assuming that the furnace is in continuous operation with pellets being charged at the top of the furnace, the motor I24 will be in continuous operation. Hence, a portion of the pellets which have been suiiiciently heated and have come to rest upon the discharge plates 13 to 11 are discharged as the latter plates are moved relative to the inclined plates 85. The extents of movements of the two end discharge plates I6 and H are so adjusted relative to that of the inter mediate plates such as 13 to I5, by means of the mechanism shown in detail in Figs. 3, 4, and 14, that the discharge of material is substantially uniform throughout the entire cross-sectional area of the furnace. Hence, the separate pellets in any horizontal layer of material within the furnace move downwardly at substantially the same rate so that all the pellets within such a hypothetical layer are subjected to substantially the same temperatures for the same periods of time.

The pellets discharged upon reciprocation of the discharge plates, I3 to IT, accumulate upon the u per valves I39 and I54 within the conduits 3|, 32 while the discharge plates are moving to the left, as viewed in Fig. 1. During this same interval, the timer, which is preferably operated by the gear reduction unit I23, energizes the motor I61 to move the lower discharge valves I5I and I5! to open positions thus discharging any material that has accumulated between the upper and lower valve plates in the conduits 3I, 32, the lower valves being again closed shortly prior to the time that the discharge plates, '13 to IT, reach their extreme left positions. As the motor I24 continues to rotate and moves the discharge plates, I3 to 11, back to their initial positions, the lower valves I5I and I5! remain closed while the timer .now energizes the motor 20I to open the upper valves I39 and I54 thus allowing the material which has accumulated thereon to move downwardly and come to rest upon the valves I5I and IST. The upper valves I39 and I54 are returned to their closed positions, due to deenergization of the motor 20I by the time that the reciprocating plates, I3 to IT, have returned to their initial positions. Upon the next cycle of movement of the discharge plates, I3 to TI, the previously described operations are repeated, this continuing so long as the motor I24 is in operation and the furnace is charged with material.

The length of time required for the pellets to pass from the top of the shaft of the furnace through the grate bars and be discharged therefrom, and hence the extent of their heating, may be controlled by regulating the speed of operation of the motor I24 and the extents of movements of the discharge plates. It will be apparent, however, that the rate of movement of the pellets through the furnace is relatively slow and that these pellets are not subjected to any appreciable grinding or breaking forces since the grate bars and discharge mechanism so function that the pellets move in relatively uniform layers downwardly through the shaft of the furnace. Moreover, the pellets are not subjected to any appreciable grinding forces in passing between the grate bars or by action of the discharge plates.

The grate bars 34 may be vibrated either continuously, or intermittently, or not at all, during the operation of the furnace and, when individual vibrators such as shown in Figs. 1, 2, and 8 are employed, any desired number of the grate bars may be vibrated at a given time. This vibration is, as noted above, preferably of relatively high frequency, short stroke type but may be of relatively low frequency when the mechanism illustrated in Figs. 15, 16 and 17 is used, the vibration being used to break up large clusters of pellets, if formed. The vibratory motion is, however, insufficient in extent of movement to effect appreciable abrasive action between the pellets and the grate bars or between adjacent pellets. It should be further noted that this vibration of the grate bars is not injurious to the lining of the furnace due to the novel manner in which the grate bars are mounted so that the vibrations are not transmitted to the furnace walls.

While the invention has been illustrated and described in considerable detail as embodied in a rectangular shaft furnace for hardening pellets of iron ore, it will be readily understood that the furnace is not limited to such a use, but may be employed for other purposes where similar problems are encountered. Furthermore, variations may be effected in the details of construction of the device and, while the invention is especially useful when embodied as a shaft furnace of rectangular cross-section, many, if not all, of the features herein disclosed may be employed without material change in shaft furnaces of circular or elliptical cross-section. Consequently, the construction described above and illustrated in the accompanying drawings is simply illustrative of a practical embodiment of the invention and, therefore, the invention is not to be considered as limited to the exact details shown and described.

Having thus described the invention, we claim:

1. A grate construction for a shaft furnace comprising a plurality of spaced substantially parallel grate bars extending transversely of the shaft of said furnace adjacent the bottom thereof, means connected with each of said grate bars and slidably extending through corresponding openings in the shell of said furnace, sealing means surrounding a portion of said means adiacent the shell of the furnace to prevent the escape of gas thereabout, the said sealing means being so constructed and arranged as to allow at least limited longitudinal movement of the said means extending therethrough, and means for applying longitudinally directed forces to the said extending means to vibrate the latter and the attached grate bars.

2. A grate construction as defined in claim 1 and further comprising means individually supporting the grate bars including a separate platelike member attached to each grate bar adjacent each end thereof and means suspending said plate-like members from the shell of said furnace in a manner permitting limited movement of the said plate-like members relative to the furnace shell.

3. A combined grate and discharge mechanism for a shaft furnace comprising a plurality of spaced substantially parallel grate bars extending transversely of the shaft of said furnace adjacent the bottom thereof, a plurality of platelike members horizontally spaced from each other and supported for transverse reciprocation in a horizontal plane and. in vertically spaced relationship below said grate bars, the upper surfaces of said plate-like members being adapted to receive and retain material moving downwardly between said grate bars, a common power means for transversely reciprocating all of said plate-like members, separate means connecting each end member of said plurality of members to said power means, and means interconnecting the others of said members together and to said power means, the several said connecting means including adjustable means for providing an adjustable lost-motion therebetween and said power means whereby the length of the stroke of said end plate-like members and of said other plate-like members may be adjusted to effect substantially uniform discharge of the material throughout the entire crosssectional area of said furnace.

i. A combined grate and discharge mechanism for a shaft furnace comprising a plurality of spaced substantially parallel grate bars extending transversely of the shaft of said furnace adjacent the bottom thereof, a plurality of members horizontally spaced from each other and supported in vertically spaced relationship below said grate bars with their upper surfaces substantially horizontal and positioned to receive and retain material moving downwardly between said grate bars, means to vibrate said grate bars to disrupt large clusters that may have formed in said material, means to transversely reciprocate said members to displace a portion of the material resting thereon, and means to adjust the extent of reciprocating movement of at least some of said members relative to that of the others to thereby effect substantially uniform discharge of the material throughout the entire cross sectional area of said furnace so that the material in any horizontal plane within the furnace moves downwardly at a substantially uniform rate.

5. A combined grate and discharge mechanism for a shaft furnace comprising a plurality of spaced substantially parallel grate bars extending transversely of the shaft of said furnace adjacent the bottom thereof, means individually supporting the ends of each grate bar on the shell of the furnace for limited movement relative thereto, a plurality of members horizontally spaced from each other and supported in vertically spaced relationship below said grate bars with their upper surfaces substantially horizontal and positioned to receive and retain material moving downwardly between said grate bars, means mounted adjacent corresponding lower longitudinal edges of each of said grate bars providing inclined surfaces extending from the said grate bars to points closely adjacent one side edge of the corresponding members to guide material onto the latter as the said material moves downwardly between said grate bars, means to vibrate said grate bars to disrupt large clusters that may have formed in said material, means to transversely reciprocate said members to displace a portion of the material resting thereon, and means to adjust the extent of reciprocating movement of at least some of said members relative to that of the others to thereby effect substantially uniform discharge of the material throughout the entire cross-sectional area of said furnace so that the material in any horizontal plane within the furnace moves downwardly at a substantially uniform rate.

6. A combined grate and discharge mechanism for a shaft furnace comprising a plurality of spaced substantially parallel grate bars extending transversely of the shaft of said furnace adjacent the bottom thereof, means for imparting oscillatory impulses to said grate bars, a plurality of members horizontally spaced from each other and supported in vertically spaced relationship below said grate bars with their upper surfaces substantially parallel and positioned to receive and retain material moving downwardly between said grate bars, means to transversely reciprocate said members to displace a portion of the material resting thereon, and means to control the discharge from said furnace of the material displaced from said members in predetermined timed relationship with the reciprocation of said members.

7. The combination as defined in claim 6, and in which said last-mentioned means includes a pair of vertically spaced valves and means to operate said valves alternately to open and closed positions in timed relationship with the reciprocation of said members.

8. A shaft furnace comprising a shell, a portion of which is provided with a lining forming a shaft-like material treating chamber, a plurality of spaced grate bars extending substantially parallel with each other and transversely of said chamber adjacent the bottom thereof, the said shell of the furnace extending below said grate bars to provide a plenum portion having openings for introduction of gas under pressure and also having a material discharge opening, a plurality of members horizontally spaced from each other and arranged in vertically spaced relationship below said grate bars with their upper surfaces substantially horizontal and positioned to receive and retain material moving downwardly between said grate bars, means to transversely reciprocate said members to displace a portion of the material resting thereon, means controlling the passage of material through said discharge opening and forming a gas seal for the latter, and means to operate the last-mentioned means in a predetermined timed relationship with the reciprocation of said members whereby material discharged from the latter is removed from said plenum substantially without loss of the gas pressure therein.

9. The combination as defined in claim 8 and in which said grate bars are individually supported for limited movement, and means for vibrating said grate bars to break large clusters that may have formed in the material.

10. A shaft furnace comprising a shell, a portion of which is provided with a lining forming a shaft-like material treating chamber, a plurality of spaced grate bars extending substantially parallel with each other and transversely of said chamber adjacent the bottom thereof, the said shell of the furnace extending below said grate bars to provide a plenum portion having openings for introduction of gas under pressure and also having a material discharge opening, a plurality of members horizontally spaced from each other and arranged in horizontally spaced relationship below said grate bars with their upper surfaces substantially horizontal and positioned to receive and retain material moving downwardly between said grate bars, means to transversely reciprocate said members to displace a portion of the material resting thereon, a pair of spaced valves controlling the passage of material through said discharge opening and form- 23 ing a gas seal for the latter, means to operate the said valves between open and closed positions in alternation so that one valve is closed when the other is open, and means to control the operation of said valves in a predetermined timed relationship with the reciprocation of said members whereby material discharged from the latter is removed from said plenum substantially without loss of the gas pressure therein.

11. A shaft furnace comprising a shell a portion of which is provided with a lining forming a shaft-like material treating chamber, a plu rality of spaced grate bars extending substantially parallel with each other and transversely of said chamber adjacent the bottom thereof, the said shell of the furnace extending below said grate bars to provide a plenum portion having openings for the introduction of gas under pressure and also having a material discharge opening, a plurality of members horizontally spaced from each other and arranged in vertically spaced relationship below said grate bars with their upper surfaces substantially horizontal and positioned to receive and retain material moving downwardly between said grate bars, means to transversely reciprocate said members to displace a portion of the material resting thereon, means to adjust the extent of reciprocating movement of at least some of said members relative to that of others of said members to thereby effect substantially uniform discharge of the material through the entire cross-sectional area of said furnace so that the material in any horizontal plane within the shaft thereof moves downwardly at a substantially uniform rate, means controlling the passage of material through said discharge opening and forming a gas seal for the latter and means to operate the last-mentioned means in a predetermined timed relationship with the reciprocation of said members whereby material discharged from the latter is removed from said plenum substantially without loss of the gas pressure therein.

JOHN J. CRAIG. JOSEPH E. DUNASKY. MILTON F. MORGAN. ADOLPH LOUIS FOELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 538,237 Cook Apr. 30, 1895 777,225 Scott Dec. 13, 1904 1,298,426 Weber Mar. 25, 1919 1,650,808 Van Brunt Nov. 29, 1927 2,451,024 Ellerbeck Oct. 12, 1948 2,552,014 Puening May 8. 1951

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