US2116725A

US2116725A - Metallurgical furnace

Info

Publication number: US2116725A
Application number: US734566A
Authority: US
Inventors: Leslie G Jenness
Original assignee: INTERMETAL CORP
Current assignee: INTERMETAL Corp
Priority date: 1934-07-11
Filing date: 1934-07-11
Publication date: 1938-05-10
Anticipated expiration: 1955-05-10

Description

y 3- L. G. J'ENNESS 2,116,725

METALLURGI CAL FURNACE Original Filed July 11, 1934 4 Sheets-Sheet l INVENTOR ATTORNEYS May 10, 1938. JENNESS 2,116,725

METALLURGICAL FURNACE Original Filed July 11, 1934 4 Sheets-Sheet 2 14 Z7 26 I v15 Z2 21 i h Z5 INVENTQR mzv. W W 2% y 1938.7 I L. e. JENNESS 2,116,725

" METALLURGICAL FURNACE Original Filed July 11, 1934 4 Sheets-Sheet 3 WW WM TI'ORNEYS May 10, 1938. L. a. JENNESS METALLURGICAL FURNACE OriginalFiled July 11, l934 4 Sheets-Sheet 4 Patented May 10, 1938 PATENT OFFICE METALLURGICAL FURNACE Leslie G. Jenness, Newark, N.- .L, assignor to Intermetal Corporation, New York, N. Y., a corporation of Delaware Application July 11, 1934, Serial No. 134,566

Renewed October 13, 1937 10 Claims.

The present invention relates to improvements in metallurgical furnaces of the multiple-hearth type and has for a general object the provision of such a furnace which is readily constructed,

5 sturdy, and adapted for eiilcient use in a variety of processes for separating metals from ores-and oxides.

More specific objects are the provisions of such a furnace featured by a furnace chamber havin 10 a rabble assembly which is suspended from a gastight bearing in the top of the furnace chamber.

provided with rabble arms and rake blades of a simple and sturdy design allowing ready assembly from interchangeable parts in combination with 15 a gas-tight receiver at the bottom for receiving discharged material and a vapor condenser connected to the top of the furnace chamber; a gastight receiver for collecting reduced materialhaving an agitator for intermingling it with oil, which is of a simple and novel design and efficient in operation; a vapor condenser constructionaliy adapted for eflicient use; an eflicient charging device of simple and novel construction; and other features of construction which collectively contribute to simplicity and efliciency of operation of the furnace.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the fea- 30 tures of construction, combination of elements and arrangement of parts, which will be exemplifled in the construction hereinafter set forth and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature ahd objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

Fig. 1-is a top plan view of the metallurgical furnace of the present invention, with parts broken away;

Fig. 2 is a vertical section taken online 2-4 of Fig. 1;

45 Fig. 3 is an enlarged horizontal section taken on line 3-3 of Fig. 2;

Fig. 4 is an enlarged horizontal section taken on line 4-4 of Fig. 2; Fig. 5 is a vertical section with 50 away taken on line 5.-5 of Fig. 1;

Fig. 6 is an enlarged vertical sectional view of the gas-tight shaft supporting bearing mounted in the top of the-furnace proper;

Fig. '7 is an enlarged vertical sectional view of the guiding bearing for the rabble shaft;

parts broken Fig. 8 is an enlarged plan view with parts in section and parts broken away of a rabble arm and rakes assembled thereon;

Fig. 9 is a side view of the rabble arm and rakes assemblage shown in Fig. 8;

Fig. 10 is a plan view of the charging device and associated hopper;

Fig. 11 is an enlarged vertical section taken on line Illl of Fig. 10 and showing the device mounted in a portion of the wall of the furnace chamber; and

i Fig. 12 is a vertical section taken on line Il -I2 of Fig. 11 with the furnace wall portion omitted.

The metallurgical furnaceof the present invention is intended primarily for processing ores of metals and oxides of metals in powdered form by treatment with gases at elevated temperatures. Two particular processes for which it is applicable are (1) the reduction of metal oxides by hydrogen; and (2) the separation of metals from ores by chloridizing the metal with sulphur dichloride and chlorine, vaporizing the metal chloride and collecting it by condensation.

. The furnace proper consists of a vertical cylinder containing a series of horizontal soles, alternate soles being apertured at the center and at the periphery for passage of material with'the peripherally apertured soles provided with central apertures to receive a shaft. The soles are supported on brackets on the inside walls of the cylinder with connections which prevent rotation of the soles but permit relative movement with the cylinder wallsso as to obviate buckling due to expansion ,at high temperature. A rotatin shaft is suspended centrally from the upper end of the furnace and guided by a bearing near the lower end. This shaft carries radial rabble arms, one set of rabble arms above each sole. The rabble arms carry rabble rake blades obliquely disposed which just clear the soles. The disposition of the rabble rake blades on the rabble arms is such that the set of blades immediately above the centrally apertured sole will gradually work a charge of powdered material from the outside of the sole to the central aperture, and the set of rake blades immediately above a peripherally apertured sole will gradually work a charge of powdered material from the center. to the p phery- Y The soles thus act as battles and the rabble rake blades move the powdered charge from the outside of one sole to its central aperture where it drops down on to the succeeding sole below and is moved by the next set of rake blades to the periphery of the last mentioned sole where it drops down on to the sole below. Thus. the rapidity with which the charge of powdered material is moved from the top to the bottom of the furnace can be regulated by the speed at which 5 the vertical shaft is rotated and by the angle, or angles, at which the rake blades are disposed with respect to the rabble arms and by the clearance between the rake blades and the soles.

The powdered material is charged into the furnace near the top of the cylinder wall, just above the uppermost sole. Charging is accomplished through a worm tube led into the side of the cylinder on a downward slope. The powdered material is supplied to the worm tube from a hopper, the top of which can be closed gas-tight if desired. However,- it has been found that usually the body of powdered material in the tube and hopper will serve as an efiicient gas-tight seal. To overcome any caking at the bottom of the hopper, a pair of shafts are provided with staggered pins and therotation of these shafts in opposite directions and passing of the pins insure the feeding of loose material to the worm. The rate of charging the powdered material into the furnace is governed by the rate at which the worm is driven.

To insure tightness at the bearing of the vertical shaft a ball and socket suspension is provided. The weight of the shaft and its rabble arms and rake blades insures a good seat of the ball in its socket and prevents the escape of any gas at this point. The lower bearing does not carry any weight but merely guides the lower end of the vertical shaft.

Electrical resistance heating elements are provided around the cylindrical wall of the furnace and so arranged that heat may be applied or cut off at all levels, or at any desired level. Outside the heating elements, suitable heat insulation is 40 provided. Pyrometer tubes inserted in the vertical wall enable the inside temperature of the furnace to be determined at any desired level.

Means are provided for admitting gas, or gases, or gas generating liquids at or near the bottom of the furnace chamber. A gas-tight vapor condenser is connected to the top of the furnace chamber for receiving gaseous or vaporousmaterial discharged from the furnace chamber and a gas-tight receiver is provided for hot pow- 50 dered material discharged at the bottom of the furnace chamber. The particular construction of the gas-tight vapor condenser and the receiver for powdered material depends upon the particular use to which the furnace is to be put.

When the furnace is used to reduce a metallic oxide by hydrogen the valuable product is the reduced metal which is discharged at the bot-.

tom of the furnace chamber and the waste product is water vapor which passes out at the top! To collect the powdered metal, a receiver, consisting of a mixing chamber, preferably a horizontal cylinder, and an agitator, is secured to the under side of the furnace chamber with a gastight joint and the cylinder is partly filled with oil into-which the metal powder falls and by which it is cooled. The agitator, preferably a central horizontal shaft with a discontinuous worm, keeps the metal powder and oil in motion toward one end of the cylinder. As the oil will 70 flow back more easily than the metal powder a sludge is produced at one end of the cylinder .with relatively clean oil at the other end and in the middle to receive new additions of metal powder. Tne'eylinder is provided with means for a to admitt hydr eaEjw-itlrig ns for s pp ing oil as needed and with means for removing the sludge of oil and metal powder when desired.

To take care .of the waste material issuing at the top of the furnace chamber a vapor condenser consisting of another chamber, preferably cylindrical, is provided into which the water vapor and any unused hydrogen is received.

Cooling coils located in the ends of this cylinder condense the water vapor which is allowed to run off by gravity through suitable water seals or traps. this cylinder tends to facilitate the rise of the gases through the furnace by the creation of a greater or less degree of vacuum. Condensed water is prevented from getting back into the furnace by a baiiie or suitable elevation around the opening from the furnace into the cylinder.

An outlet is also provided for excess hydrogen which can be piped out-doors or to some place where it will not create a dangerous condition, or can e. irified and recycled.

When the furnace is used for separating metals from ores by a chloridizing and vaporizing process the desired metal compounds pass out at the top -of the furnace chamber in the form of vaporized metal chlorides and the waste material from the ore passes out at the bottom of the furnace chamber in the form of a powder. For such use, the furnace is provided with any suitable gas-tight receiver to receive the powder discharged at the bottom, connected by a. gas-tight joint with the bottom opening. Sulphur dichloride which is a liquid is introduced through the side wall of the furnace near the bottom and is vaporized-by the heat in the furnace. The introduction may be made at one or more levels as demanded by the process being carried on in the furnace. Chlorine, which is a gas at "ordinary temperature, is also introduced through the side wall of the furnace preferably with the sulphur dichloride.

The vaporized metal chlorides which result from the reaction pass out at the top of the furnace chamber and are condensed in a vapor condenser consisting of suitable gas-tight receivers by lowering the temperatures. may be carried out in this furnace as selective separations by control of the furnace temperature so as to chloridize and vaporize one metal from the ore at a time, or they may be carried out at a temperature sufiiciently highto chloridize and vaporize two or more metals in the ore and the resultant metal chlorides separated by fractional condensation.

Referring to the drawings for a more detailed description of the invention like numerals refer to like parts throughout:

A vertically disposed furnace chamber consisting of a cylinder I3 is provided with a flange It at the top to which is bolted a top plate IS, a flange l6 at the bottom to which is bolted a bottom plate I! provided with a discharge passage having a flange I9 to which is bolted in a gas-tight manner the inlet opening of a gastight receiver which may be a mixing chamber 20, hereinafter more fully described, or a gastight receptacle as required by the use to which the metallurgical furnace is put. Around the walls of the furnace are disposed series of electrical heating elements 2 I-2I overlaid by a layer of insulating material 22 and through the walls of the furnace at various levels are positioned pyrometer tubes 23-23 whereby the heat in any particular zone in the furnace may be determined. The heating elements 2l-2| are adept- Such a process The condensation of the water vapor in nately arranged, the soles 24-24 being apertured at the center and thesoles 25-25 being apertured at the periphery thereof for passage of material with the soles 25-25 additionally apertured at the center for receiving a shaft, as is more particularly shown in Figs. 3 and 4. A baffle plate 26 is mounted above the upper sole 24 and is of similar construction.

A verticle shaft 21 is suspended centrally from the'top of the furnace by a gas-tight bearing assembly 28 and guided in a bearing 29 in the lower sole 25. Upon the vertical shaft 21 are mounted a series of collars 30-30, each,..collar being located above one of the soles 24-24 and 25-25 and consisting of at least two sections 3|, 3| bolted together whereby the collar may be clamped upon the shaft 21 in any desired position.

A rabble arm 32 is mounted upon each section 3|, preferably being threaded into a tapped hole as shown in Fig. 8. A sleeve 33 is mounted upon the rabble arm 32 and has a face of one end abutting a shoulder 34 on the section 3|. The

angle to the axis of the rabble arm 32 preferably at an angle of 45 and is mounted upon the rabble arm 32 to abut against the face of the end of the sleeve 33. A similar rabble plate or rake blade 36 is mounted in a similar manner upon the rabble arm 32 and spaced from the rake blade by a spacing sleeve 31 having the faces of the ends thereof disposed at angles to abut against the adjacent faces of the

rake blades

35 and 36. An additional rabble plate or rake blade 38 is mounted upon the rabble, arm 32 in a similar manner; The rake blade 38 is similar in all respects to the

rake blades

35 and 36 ex cept that it is of greater width to provide a leading edge as depicted in Fig. 8. A spacing sleeve 39, similar to the spacing sleeve 31, is mounted between the

rake blades

36 and 38. To secure the assemblage in position upon the rabble arm 32 an additional sleeve 40 is provided having the face of one end engaging the adjacent face of the rake blade 38 and the other end engaged by a head M of a bolt 42 threaded into a tapped hole in the outer end of the rabble arm 32.

Such structure allows ready assembling of the rabble plates or rake blades on the rabble arms 32 and any desired arrangement, as illustrated in Figs. 3 and 4 and illustrated in Fig. 8 in full and dot-dash lines, whereby ore material may be worked across the soles either toward the centers thereof or toward the peripheries thereof at any desired speed. If desired, a spacing sleeve 43 having the faces of the ends thereof disposed atright angles to each other and at substantially to the axis of the rabble arm 32 may be substituted. for the spacing sleeve 39 between rake blades 36 and 38 'on one of the rabble arms 32-32 in the rabble assemblages above soles 25-25 structure adjacent the walls of the furnace chamber.

- Opposite each of the soles 25-25 in-the wall of the furnace chamber is preferably provided an inspection hole. not shown, suitably closed by a gas-tight cover to allow ready inspection and adjustment of the rabble rake assemblages abovethe

soles

24 and 25.

The soles 24-24 are made of a diameter slightly smaller than the inside diameter of the fur-.

nace chamber and supported upon suitable supports 44-44 to permit relative movement with the chamber walls so as to obviate buckling due to expansion at high temperatures, while preventing rotation of the soles. Similar provisions are made for mounting the soles2525..

The powdered ore material is charged into the furnace near the top of the furnace chamber just above the top sole 24 and below the baiile plate 26 by a charging device 45 consisting of a worm tube 46 having an end 41 arranged to project through the wall I3 and provided with a mounting flange 48. The worm tube 46 is inclined downwardly as shown to facilitate travel of the powdered ore material. In the upper end of the worm tube 46 is seated a bearing structure 49 having a sealing ring 50 threaded therein. A feeding worm 5| is positioned within the worm tube 46 and a shaft.52 for the feeding worm projects through the sealing ring 50 and hearing structure 49 and has a bevel gear 53 keyed to the end thereof. A bracket 54 rotatably supports a bevel gear 55 meshed with the bevel gear 53 and a spur gear 56 keyed with the bevel gear 55.

A casting 51 having a passage 58 is mounted vertically upon the worm tube 46 with the passage 58 aligned with an aperture in the worm tube 46 as shown. A hopper 59 is mounted upon the casting51 and, if desired, may be provided with a cover to insure gas-tightness.

A pair of shafts 6|], 6|) are horizontally disposed side by side within the passage 58 with the inner ends seated in supporting recesses and the outer ends reduced and rotatably mounted in bearingstructures 6|, 6| supported, by the casting 51. Meshed pinions 62, 62 are keyed to the ends of the

shafts

60, 66. A plurality of pins 63-63 are mounted on each-of the shafts 66, of a length sufficient just to clear the adjacent shaft and arranged on both

shafts

66, 66 in alternate fashion so that they will pass each other in rotation of the

shafts

66,60. The

pinions

62,62 being in mesh will rotate the shafts 60, .60 in opposite directions so that when operated with the pins 63-63 moving downwardly between .the

shafts

60, 66

the powdered ore material in the-bottom of the hopper. will be agitated andfed into the worm' tube 46.

A rotatable shaft 64 is mounted on one side of the casting 51 and is provided with a spur gear 65 keyed thereto in mesh with spur gear 56 and a spur gear'66 keyed thereto in meshwith one of the

pinions

62, 62. Any suitable means are provided for rotating the shaft 64 so that the feeding worm 5| and the agitating

shafts

66, 66 may be simultaneously operated.

The rabble shaft 21, as has been previously indicated, is supported from the top of the furnace chamber by a gas-tight bearing structure 28. This bearing structure consists of a collar 61 mounted upon the top plate l5, preferably welded thereto. A centrally disposed hole in the.collar 61 is alignedwith a hole in the plate i5 and internally threaded at 68 as shown in Fig. 6. The

collar 61 is also provided with a recess 99 in which is seated a gasket 10 of suitable material. A socket member II is mounted upon the collar 61 provided with a threaded neck I2 threaded into the threaded aligned holes in the collar 6? and the plate 85 with the gasket 60 acting as an eflicient seal between the collar Bi and a portion of the socket II. A collar 89 is mounted, preferably threaded, upon the rabble .shaft 21. The

collar I3 is provided with a lower crowned ,sup-.

gas-tight manner. However, in order to augment the-gas-tightness of the bearing the collar 13 is provided with a threaded neck I5 engaged by an internally threaded ring it recessed at W to confine a gasket I8 between the wall of the socket I and the ring it.

' rotated by the shaft 85 in a direction so that re-' When the metallurgical furnace is used for the reduction of metal oxides by hydrogen a gas-tight receiver comprising the mixing chamber 20 is bolted to flange It in a gas-tight manner with the passage 98 aligned with an inlet passage 19 in the top of a horizontally disposed cylinder 80 and adjacent one end thereof. The horizontally disposed cylinder 90 is provided at one end with a closure plate 8! having on the inner face thereof a supporting bearing 82 and at the other end P with'a closure plate 93 having a bearing structure 89 mounted therein. A rotatable shaft 05 is mounted in the

bearings

92 and 89 with one end thereof projecting through the bearing structure 89 for application of motive power. Upon the shaft 95 are mounted a series of angularly disposed blades 8096 to form a discontinuous worm. At the inlet end of the chamber 90 is provided a hydrogen inlet 81, and at the other end of the chamber 90, hereinafter called the discharge end, is provided a suitable discharge conduit 08 and an oil inlet 99, the oil inlet preferably being located in the top of the cylinder 80, as shown, for gravity flow of oil. The blades. 86 are duced ore material discharged from the furnace chamber into the mixing chamber will be worked toward the discharge conduit 00. The discharge conduit 80 may be connected by a suitable conduit 90 to a pump or other means to draw off a sludge of oil and reduced ore material when de=- sired. I

In reducing metal oxides with hydrogen, means are provided for carrying away and condensing the water vapor formed by combining the hydrogen with oxygen from the ore, and for carrying away excess hydrogen. A vapor condenser 9! is provided for this purpose consisting of a horizon- .tally disposed cylinder 92 closed at the ends thereof by

plates

93, 93 and connected by a passage 94 with an opening in the plate ii at the top of the furnace chamber. Around the passage 94 is provided a suitable baille 95 to prevent back flow into the furnace chamber of condensed water vapor. Suitable cooling coils 96, 96 are provided in the ends of the condenser. Water is carried off from the condenser by

suitable conduits

91, 91 provided with pot heads 90, 90 each of which consists of a container into which the conduit 91 projects below an utlet 99. Conduits I00, I are also provided in the top of the condenser cylinder 92 to carry off excess hydrogen. Each of the conduits I00, I00 is also provided with a pot heat IM to act as a water seal.

In operation powdered ore material is placed within the hopper 59 which, if desired, may be supplied with a gas-tight cover. However, the

mass of powdered material in the hopper acts as an efiicient gas-tight seal. The shaft 60 is rotated so that the pins 63--63 on the

shafts

60, 60 will agitate the powdered ore material to prevent caking and to insure positive feeding of the ore material to the feeding worm i which is likewise operated by rotation of the shaft 09. Powdered ore material drops down upon the upper sole 29. The bailie plate 26 being disposed thereabove prevents dust and the like from being carried ofi with the gaseous or vaporous material discharged from the top of the furnace chamber. The rabble shaft 21 is rotated to the right so that vthe rake blades above the upper sole 24 will work the ore material toward the aperture in the center thereof. The ore material then drops down upon the soIIStherebelow and is worked by the rake blades toward the apertures in the periphery thereof. The rapidity with which the charge of powdered material is moved from the top to the bottom of the furnace chamber is regulated by the speed with which the rabble shaft is rotated, by the angle, or angles, at which the rake blades are disposed with respect to the rab-.

ble arm, and by the clearance between the rake blades and the soles.

When the metallurgical furnace is used to reduce'metal oxides by hydrogen, the hydrogen is introduced through the inlet 81 in the mixing chamber 20 and rises through the outlet I8 in the furnace chamber up past the charge of powdered material as the latter is gradually worked down through the furnace chamber. The waste material consists of water vapor and excess hydrogen which will discharge from the top of the furnace chamber into the vapor condenser 9| where the water vapor is condensed and discharged through the

conduits

91, 91 and the excess hydrogen is discharged throughthe conduits I00, I00 to be carried away as waste material or to be purified and recycled. Oil is introduced into the mixing chamber 20 through theinlet 89 and reduced ore material is discharged from the furnace chamber through the passage l0 into the mixing chamber 20. The shaft 85 is rotated to the right so that the powdered ore material and oil will be thoroughly mixed together to form a sludge which is gradually worked toward the discharge conduit 90 through which it may be removed as desired by any vsuitable means such as a pump.

when the metallurgical furnace is used for the separation of metals from ores by chloridizing the metal with sulphur dichloride and chlorine, waste material in powdered form is discharged through the passage l8 into a gas-tight receiver of any suitable construction connected by a gastight joint to the flange l9 and the desired metal compounds pass out at the top of the furnace chamber in the form of vaporized metal chlorides into a vapor condenser. Selective separations may be carried out by control of the furnace temperature so as to chlcridize and vaporize one metal from the ore at a time and condensation of the vapor in a gas-tight container by lowering the temperature, or by cpntrol of the furnace temper ature sumciently high to chlcridize and vaporize two or more metals in the ore and fractional condensation in successive gas-tight. containers by lowering the temperature to a predetermined furnace near the bottom of the furnace chamber at one or more levels as demanded by the process beingcarrled out.

It will thus be seen that the present invention attains in an efficient manner the objects set forth above. Since certain changesmay be made in the above construction and different 'embbdiments of the invention could be made without departing fromthe scope'thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative andnot in a limiting sense.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

sealing said enlarged portion in said socket in a gas-tight manner.

2. In a metallurgical furnace the combination with a gas-tight furnace chamber, of a rabble assemblage' including a vertical rabble shaft, a collar on said shaft having a lower spherical bearing surface, a socket in the top of said chamber to receive said collar and having a mating bearing surface, and sealing means between said collar and said socket.

3. In a metallurgical furnace the combination with a gas-tight furnace chamber, of a rabble assemblage including a vertical rabble shaft, a collar threaded on said shaft, said collar having a lower crowned bearing surface and a threaded portion, a socket sealed into the top ,of said' chamber, said socket having a central aperture to receive said shaft and a matingbearing surface, a gasket between said threaded portion and the wall of said socket, and a ring threaded on said threaded portion to expand said gasket for a gas-tight seal. a

4. In a metallurgical furnace a rabble arm mounted on a vertical rabble, a plurality of flat plate rake blades each having a hole therethrough the ams of which is disposed at an oblique angle to the axis of said rabble arm with said rabble arm received therein, spacing sleeves mounted on said rabble arm betweensaid rake blades and having surfaces at'the ends thereof abutting the surfaces of said rake blades, and 7 means securing said sleeves and said rakeblades on said rabble arm.

'5. In a metallurgical furnace a rabble arm mounted on a vertical rabble, a plurality of flat plate rakes blades each having a hole therethrough the axis of which is disposed at an oblique angle to abut the surfaces of said rake blades, a

similar sleeve beyond the outermost rake blade, and a bolt threaded into the end of said rabble arm having a head engaging the outermost end of said last mentioned sleeve whereby said rake blades and sleeves are secured on said rabble arm. 6. In a metallurgical furnace a vertical rabble shaft, a collar mounted on said shaft, said collar being formed from sections, means to secure said sections together and clamp said collar in any desired position on said shaft, a rabble arm mounted on each of said sections, a

plurality of flat plate rake blades each having a hole therethrough the axis of which is disposed at an oblique angle to the axis of said rabble arm with said rabble arm received therein, spacing sleeves mounted on said rabble arm between said collar and the innermost rake blade, between said rake blades and beyond the outermost rake blade,

said spacing sleeves having the ends thereof formed at an angle to abut the surfaces of said rake blades, and a bolt threaded into the end of said rabblearm having a head engaging the outermost end of the outermost sleeve whereby said rake blades and sleeves are secured onsaid rabble armQ 7. In a metallurgical furnace the combination with a furnace chamber having at least one horizontally disposed sole, of a vertical rabble shaft having an enlarged portion provided with a crowned supporting*bearing surface, a socket in the top of said chamber to receive said enlarged portion and having a mating bearing surface, means sealing said enlarged portion in said socket in a gas-tight manner, a collar mounted on said shaft, said collar being formed from sections, means to secure said sections together and clamp said collar in any desired position on said shaft above the sole, a rabble arm mounted on each of said sections, a plurality of flat plate rake blades each having a hole therethrough the axis of which is disposed at an oblique angle to the axis of said rabble arm with said rabble arm received therein, spacing sleeves mounted on said rabble arm between said collar and the innermost rake blade, between said rake blades, and beyond the outermost rake blade, said spacing sleeves having the end thereof formed at an angle to abut the surfaces of said rake blades, and a bolt threaded into the end of said rabble arm having a head engaging the outermost end of the outermost sleeve whereby said rake blades .and sleeves are secured on said rabble arm.

8. Ina metallurgical furnace the combination with a furnace chamber provided with a series of horizontally disposed soles'alternately apertured near the center and near the periphery, of a rabmeans sealing, said enlarged portion in said sock-.

et in a gas-tight manner, a plurality of collars mounted on said shaft between the soles, each of said collars being formed from sections, means to secure said sections together and clamp each of said collars in any desired positionon said shaft above the associated sole, a rabble arm mounted on each of said sections, a plurality of flat plate rake blades each having a hole therethrough the axis of which is disposed at an oblique angle to the axis of said rabble arm received therein, spacing sleeves mounted on said rabble arm between said associated collar and the innermost rake blade on said arm, between said rake blades, and beyond the outermost rake blade on said arm, said spacing sleeves having the "ends thereof formed at an angle to abut the surfaces of said rake blades, a bolt threaded into the end of said rabble arm having a head engaging the outermost end of the outermost sleeve whereby said rake blades and sleeves are secured on said .asso

at angles to work ores across said soles toward the apertures therein, and a guiding bearing for said rabble shaft in the lower portion of said chamstantially vertically disposed passage opening into said tube above said worm, a hopper communicating with said passage, a pair of rotatable horizontally disposed shafts located in said passage, pins on said shafts alternately positioned so that those on one shaft will pass those on thesother shaft, means to rotate said shafts in opposite directions with the pins of one shaft passing downwa rdly.on the side adjacent the compliment shaft, and means simultaneously to operate said worm shaft and said rotating means.

2,116,725 ciated rabble arms with the rake blades disposed 10. In a metallurgical furnace a charging device comprising a. worm tube inclined downwardly to supply powdered ore material to the furnace chamber, a. worm in said tube, a worm shaft projected through a gas-tight fitting in the end of said tube and supported by bearings therein, a substantially vertically disposed passage opening into said tube above said worm, a hopper mounted on the upper end of said passage,a pair of rotatable horizontally disposed shafts located sidev by side in said passage, pins on said shafts alternately positioned so that those on one shaft will pass those on the other shaft, meshed gears on said shafts whereby said shafts may be operated in opposite directions, and common driving means geared to said worm shaft'and to said interengaging gears whereby all of said shafts may be operated simultaneously with the pins of one horizontally disposed shaft passing downwardly on the side adjacent the compliment shaft.

LESLIE G. JENNESS.