US1388144A - Mechanically-operated scotch hearth - Google Patents

Description

w: E. NEwNAM. MECHANICALLY OPERATED SCOTCH HEARTH.. APPLICATION FILED APR. 3. i916.- RENEWED NOV. 4 1918.

mmaAug.16',1921.

3 SHEETS-SHE W. E. NEWNAM.

MECHANWALLY OPERATED-SCOTCH HEARTH. APPLlcAloN FILED APR. 3. 19m. www Nov.'4. 191s.

1,388,144. f, Patented Aug. i6, 192L SHEETS-SHEET 2.

W. E. NEWNAM.- NIECHANICALLY OPI-:RATED SCOTCH HEARTH. APPLICATION FILED APR. 3, 191s. IIIsNI-:wED Nov. 4. Isls.

1,388,14A. Y Patented Aug. 16, 1921..l

v 3 'SHEETS-HEET 3- NEW JERSEY.

Application led April '3,

To all whom t may concern i Be it known that I, WILLIAM E. N EWNAM,

a cltizen of the United States, and residing at Collinsville, in the county of Madison and State of Illinois, have invented' a certain newand useful Improvement in Mechanically-Qperated Scotch Hearths, of which the this bed or bath of molten lead in the wardly and are caught fo lowing is a specification.

This invention relates to smelting furnaces, and more particularly to smelting furnaces of the. Scotch or ore hearth type, which are used for smelting lea n A Scotch or ore hearth, especially as used in "America, comprises a comparatively deep basin of cast twyers at the lower end thereof positioned just above the basin, an apron which. extends forwardly from the basin, and a hood which extends over the hearth. In the operation of such a furnace the basin is filled nearly full of lead, which is then melted by building a fire on the hearth. The ore and fuel are then placed so as to' floaton top of basin and banked up against the water back. If a blast is now applied to the twyers,a part of the ore is reduced to molten lead, which settles in the basin, the unmelted clinker being used as a blast furnace product. In the operation of the hearth, the workman rabbles or works up the ore and fuel, (which'is usually coke) banked against the waterback, this rabbling being accomplished 'by inserting the rabbling device, which is in the form of a bar, into the basin, and, usingthe` front edge of the basin as a fulcrum, bearing down on the end of the rabble so as to turn over and Work up the material onthe hearthand bring the gray clinker to the surface.` This rabbling proceeds from one end to the'other of the hearth, and is succeeded by a leveling operation. workman will use level the material against the water back, the clin'ker bein picked out and removed from the hearth for subsequent use in the blast furnace. 4The Workman will then add small quantities of ore and fuel in; ground condition. During the rabbling operation the molten lead will overflow and discharge into molds to form pig lead. The fumes given off during the sm-elting operation pass upby the hood, from whence they pass to the bag 1ron, awater /back havingl In this levelingl operation the.l

a shovel and push back or Fica.

MECHANICALLY-OPERATED SCTCH HEARTH.

they are collected. Now the operation of such a hearth not only requires a. considerable amount of manual labor, but, l1n view of the presence and escape of polsonous lead fumes, it is diflicult workmen.

In the operation of the usual hand rabbled ore hearth, the fume losses are not only great, but the recovery of metal is relatively small. This is due to the fact that the rab bling is not only irregular, but the rabbled charge `is exposed for considerable periods of time, thereby causing the oxidation of a considerable amount of lead which -passes into the flue as fume.

Some of the objects of this invention, therefore, are to provide an improved furnace of the above type in which the rabbling operation will be performed mechanically, so as to reduce the manual labor and increase the output of a furnace, and to provide means whereby the fumes are carried oil so as not to escape in the vicinity of the Workmen.

Another object is to provide a mechanicallyvoperated rabbling device for a furnace ofthe above type which is simple in construction, effective in its operation, and reliable. i Further objects tail description taken in connection with the accompanying drawings, in which:

Figure 1 is a front elevation of a furnace embodyingthis invention;

Fig. 2 isa section on the line 2 2, Fig. 1, showing the carriage and furnace in side elevation y Fig. 3 is a detail plan view ofthe carriage; l

' Fig. 4 is a detail side elevation of Fig. 3, showing the clutch operating mechanism;

Fig. 5 is a detail Fig. 1, showing-the nism;

Fig. 6 is a side view of Fig. 5

Fig. 7 is a section on the line 7f3?, Fig. 2,

to obtain and retain sectionon the line 5 5,

house, where will appear from the deshowlng the automatic, stopping mechanism f Fig. 9 is a section through the furnace,

' designates the furnace connection being shown at 6, while the blast duct 13 extending to the turn discharging into and a side elevation of the rabbling device; and Fig. 1Q is a detail section on the line 10-1o,Fig. 9.

Referring to the accompanying drawings,

and moreparticularly, to Figs. 1, 2 and 9, 1

base, which is provided With a cast iron basin 2, an apron 3, and a water back 4 having twyers 5. The water back extends along the back and sid'es of the hearth, and is cast hollow, as usual in Scotch hearth constructions, the water pipe connection is shown at 7. A hood 8, of usual construction, extends over the hearth and discharges into pipes 9, these pipes in a flue common .to a number of furnaces and leading to the bag house. The hearth so far described may be of usual construction, although -it is for practical purposes, made longer than the usual Scotch or ore hearth.

Spaced from themain hood 8 is an exhaust hood 10 discharging into pipes 11 also spaced from the pipes 9, and leading to a common iue which discharges into a stack. The space between the hoods will, therefore, be heated, and this heat will cause an induced draft between the hoods, which `will carry eff any gaseswhich may not be caught by the main hood. A spout 12 is formed on one end of the basin, and isconnected by a bottom of the basin, discharge from the a carrier or 16 across the so that the overflow can spout into molds 14 carried by carriage 15 movable on a track i end of the furnace.

Mounted in front of the furnace are pairs of braced standards 20, which carry rails 21. A carriage 22, preferably of structural material, has wheels 23 and 24 running o n the rails whereb the carriage is suspended for movement along the hearth. The wheels 23 are fixed to a shaft V25 on the carriage, and

to this shaft is fixed a ratchet 26, engaged by a pawl 27 on a pawl carrier 28, loosely mounted on the shaft and connected by a link 29 with an arm 30 pivoted on a bracket 31 fixed to a cross beam 32 of the'carriage. The arm 30 is provided with a series of apertures 33, any one of which is adapted to receive the cross pin an eccentric rod 35, which carries at its lower end a strap 36 engaging an eccentric .37 on a shaft 38 mounted in bearingson the carriage 22. This shaft has loosely mountedthereon, but adapted to be clutched therea gear 39 meshing with a pinion 40 on a shaft 41' also mounted in bearings on the carriage, and having fixed thereto a Wheel 42 and a gear 43 meshing with a pinion 44 en the shaftof an electric motor 45 mounted on the carriage. With this construction', the motor 45 will rotate the shaft 38. at reduced speed, and this will, through 34 on the upper end of` the eccentric connections to the pawl and ratchet, move the carriage step by step from left to right, Fig. 1,` along the hearth.

Fixed to the shaft 38 at is a crank disk 50, the crank pin 51 of which is swiveled therein and terminates in a yoke 52 and a strap 53 pivoted at 54 on the yoke,

as llea hand end' and having a slot 55 therein 'adapted to aline` a bar,

end of device being retained by colwit the crank pin. The free end of the rabbling device is supported by a fork carried by a bracket 61 on the carriage 22. Rota. tion of the shaft 38 will thus cause the point of the rabbling device to perform a rab. bling movement, .corresponding closely to the movement given by the workman, in the elliptical path as shown in Fig. 9. vOn account of the yieldingconnection between the rabbling device and its operating mechanism, the accidental engagement of the point 0f the rabbling device with the basin or water back, or with a hard substance therebetween, will avoid breakage. Furthermore, the connection permits ready detachment of the rabbling device from its crank, so as to permit replacement.

The hub of the gear 39 has fixed thereto a sprocket 65 connected by a chain 66 with a sprocket 67 loosel mounted on a countershaft 68, but provi ed with a jaw clutch 69 adapted to engage a clutch sleeve'70 splined on the shaft 68. The shaft 68 has fixed thereto a bevel gear 71 meshingfwith a coperating bevel gear 72 fixed to. a shaft 73 on the carriage 22, to which shaft are also fixed the wheels 24. The clutch` sleeve is normally out of engagement with the coperating clutch 69, but is carried by an arm pivoted at 75 on a cross beam 76 on the carriage 22, and connected by a link 760 with an arm 77 'on a rock shaft 78 mounted in bearings on the carriage, and having an arm 79 to which is attached a link 80 provided with a handle, as shown in Fig. 1. When the link 80 is drawn down, the clutch sleeve 70 is thrown into engagement with the clutch69 carried by the sprocket 67, so that, if the pawl 27 is inactive, as hereinafter described, the carriage will be moved by continuous movement from ri ht to left, Fig. 1. vLocated'in the path of t e arm 74, fixed to one of the rails 21,

Oil

' sleeve 930 splined to the .moved toward the clutch the arm 89. The free end lper end of a link 88, the lower end A shield 82 on a carrier 83 loosely mounted n the shaft 25 extends over the ratchet 26. This shield carrier is connectedby a link 84 with an arm 85 on a rock shaft 86 mounted in bearings between the rails 21. This rock shaft has an arm 87 connected with the upof which arm 89 pivoted at 90 on f bears,

1s connected to an the carriage. A spring 91 on the link at one end, against a collar 92 and, at the other end, against a bracket 93 on one of the rails 21. The gear 39 has a clutch jaw 920 coperating with a clutch shaft and normally jaw 920 by a spring 94, one end of which bears a ainst the clutch sleeve 930, and the other end)r of which bears against a collar 95 on the shaft. The .collar`95 has a flange 96 provided with a cam 97 adapted to be engaged by a cam roll 98 on of the arm 89 is guided by a post 980 on the cross beam 99 of the' carriage, and is adapted to coperate with a latch 100 pivoted at its lower end, provided with a bevel tooth 101, and having a spring 102 which normally tends to move the latch to the left, Fig. 1, and to the right,

Fig. 7. The rock shaft 86 has an arm 103 ment to clutch the provided with a cam roll 104 adapted to ride on a stationary cam 105 fixed to Ythe right end, Fig. 1, of one of the rails 21. A

Assuming the carriage to be at the left end of the hearth, but with the parts of the' carriage in the position shown in Fig. l, that is, with the arm 89 down so that the clutch jaws 920 and 930 will be in engagegear 39 to the arm 89, with the clutch jaws gagement, and with the shield 82 in a position so that it will not be engaged by the pawl during its reciprocations, the operation will then be as follows: Rotation of the shaft will cause the rabbling device to moveJ into and out of the material 'on the hearth, in the path shown in Fig. 9, and this movement of the shaft 38 will, furthermore,'cause the pawl to reciprocatel and feed the carria e step by step. The crank connected with the rabbling device, and the eccentric connectedV with the pawlare so relatively positioned that the pawl will move back over the ratchet, while the rabbling device moves from the position a to the position b, F ig. 9, in the direction of the arrow, and will positively move the ratchet while -the rabbling device moves from the point b to the point a in the direction of the arrow. The carriage is thus stationary while the rabbling device is moving into the material, and is fed while the rabbling device terial on the hearth. The carriage will thus be fed step by step from theI left to "right, Fig. 1, and for each step the rabbling device will execute one complete movement. By a proper proportioning of the feed, which can on the link, 7

69and 70 out of en,-

Y the clutch jaws moves outof the ma'- The step by step feeding be accomplished by adjustment of the pin 34 along the arm 30, a proper rabbling of the material on the hearth may be obtained.

s the carriage comes to the position shown in Fig. 1, that is, as the rabblin device approaches the right end wall o? the water4 back, the cam roll 104 will ride on the cam 105, thereby oscillating the rock shaft 86 in the direction of the arrow,.Figs. l and This will throw' the pawl shield 82 over` the ratchet in the direction of the arrow, Fig. 7, to the position shown in that figure,

so that the pawl 27 vwill be thrown out of rock shaft 86 will, furthermore, raise the link 88 and carry with it the arm 89, so as to throw the cam roll 98 in the pathof the cam 97, whereby, upon rotation of the sleeve 930, the latter will be moved to the left, Fig. 8,- and positively withdraw the clutch sleeve 930 out of engagement with the jaw 920, and thus disconnect the shaft 38 from the gear 39. The result is, therefore, that the shaft 38 will come to rest. The spring 94 1s made strong enough so that the frictional engagement of the cam 97 with the roll 98 will act as a brake and stop the shaft in the position shown in Fig. 8. Furthermore, the cam 97 is so positioned on the shaft 38, and with respect to the crank 50, that the shaft will be stopped with the rabbling device in retracted position, and with the point thereof at the extreme retracted position a, Fig. 9. The upward movement of the arm 89, Figs. l and 7, will cause the free end thereof to'snap past the tooth 101 on the latch 100, which will now take under the arm and lock it in raised position. It will, therefore, be seen that the carriage and the rabbling device will, at the end of the feeding movement of the carriage, be held in posltion with the operating mechanisms therefor rendered inoperative.

Toy return the carriage, the workman will pull down on the link 80, thereby connecting 69 and 70 and causing the carriage to move from right to left," Fig. 1, to starting position, the step by step feeding mechanism, as well as the rabbling operating mechanism, remaining inoperative during this movement. At the end of the-return movement, the clutch jaws 69-70 `will be automatically disconnected, as heretofore described. To again throw the step by step feeding mechanism and the rabbling operating mechanism into action, the workman will simply move the latch 100 to the right, Fig. 1, which will drop the arm 89, thereby permitting thespring 94 to movethe clutch jaw 930 into engagement with the clutch jaw 920, and throwing back the pawl shield 82. mechanism will then again be thrown into operation to -feed the carriage along the hearth, and the rabbling operating mechanism will be thrown into operation to rabble the material on the hearth. It will thus be noted'that the carriage is fed, during the rabbling operation, with a slow step by lstep movement, and is returned by a continuous movement, the gearin gl being' such as to give a slow feeding` movement and a quick return movement.

In the operationof this ore hearth, two

men, a charger and a' helper operate the furnace.v A thin layer ofconcentrates hav 1 ing been spread over the charge on the the gray slag,

. and the charge vfree from the slag must be pushed back ontol the hearth. The'helper, therefore, follows closely behind the rabbler, and with a long handled shovel pushes back the loose charge, picking out the gray slag as he goes along and throwing this slag -into a car for subsequent smelting.

When this is done, a new charge of fresh ore must be immediately spread over the surface; consequently, closely behind the helper comes the charger, who spreads a thin layer of ore on the charge as fast as it is shoveled back by the helper, adding merely rake the material,

coke breeze asv needed. At the end of therabbling operation, the carriage will come to rest and will then out of action. ByA the time that the carriage has returned, the portion of the-charge on the left of the' furnace will have been smelted and is again ready to be rabbled, the operation again being performed as heretofore described, Periodically, the bar will be inserted into the passage 13 and the molten lead will flow freely into the molds 14, which are then wheeled away. A

In an ore hearth, it is not sufficient to but it must be rabbled in a certain way. pose of the rabbler is, of course, the gray slag to picked olf bythe helper.- VMoreover, the Ycharge must' not be exposed too much, for if this is' done, the hot ore will oxidize and pass into the flue as fume, thereby reducing the amount of metal* which isV extracted. It is,.therefore, necessary in practical o peration that a'step by step movement be imarted to the carriage,

is stationary in a direction along the 'hearth to bring The prime p ur.

the top so that it-can be.

so that the rabblerA is necessary in while it is buried in the bed, and is moved while out of the bed. If this rabbler were fed along the hearth while in the bed, then it would drag the slag along the bed of ore and fuel, so that the slag would not be moved. to the top and onto the surface as successful ore hearth operations. For practical and successful operations the rabblermust, therefore, be given a simple movement from the bottom to the top of the bed on the hearth so as to work ingly, each portion of the\ charge is given a be returned to its startving point with the rabbler withdrawn and up the bed. Accordingly, a step by step movement is necessary and accordingly the carriage inust be moved while the rabbler is withdrawn.

` In the smelting ofleadon ancre hearth, the smelting must be proceeded with for a. certain length of time after rabbling and. before again rabbling. rabbler would operate on the bed while lit is moving back as well as forth, then it would start to rabble a portion which has just been rabbled, and on which a fresh charge of ore had just vbeen placed, before this portion had been smelted. In accordance with this invention the charge is rabbled in one direction while the return movev ment of the carriage is an idle one. Accordcertain amount of time for smelting before it is again rabbled, and the smelting and rabbling,4 therefore, is uniform as to time and space. By rabbling the bed in one direction only and by constructing the mechanism so that the helper .and charger can follow right up behind the .rabbler, each rabbled portion is exposed for a short period only, portion is rabbled, and as each portion is rabbled, the slag is' picked out of the same.

In view of the fact that thesmelting of a charge requires in practice only about ltwo sults.

minutes, and that any excess is not only a waste of fuel, but also of metal passing off as fume, it will be appreciated that any mechanism or manipulation which closely regulates -the timing of the rabbling and smelting operations, will secure the best ,re-

In an ore hearth, the blast should be kept, as low as possible consistent with proper operation, because a high blast has a tendency to increase the temperature, causing .volatilizatioh of the metal. Moreover,- the exhaust of the gases through thehood should not be any more than necessary to keep the working atmosphere free om fume and-dust; if the suction is excessive,` part of the metal and ore is vcarried into the-V flue thereby reducing the extraction.

It will,`therefore,. be seen that there are a number of factors entering into'thevsuccessful operation of an ore hearth which determinethe extraction. Accordingly, the length of a hearth, especially when mechanically rabbled is limited. A long continuous struc- 1 If, of course, the

and is immediately covered vas 'each .charger Will secure the .ture is impracticable because it is not elastic,

over, in a multiple structure, the operation pf one part is dependent on the other, so that4 1f one part operates improperly or freezes up, the whole structure must be shut down. A unit-ary hearth of a length sufiicient to permit its attendance byl a helper and a best results. Accordingly, the length of the hearth is proportioned to correspond to the movement of the rabbler and to the period of smelting ofthe ore added to the hearthby operatives. In' this Way, where a smelting plant utilizes a number of such hearths, one hearth is independent of all of the other hearths.- As a practical proposition, -therefore, a hearth eight feet in length attended by a helper and a charger, and in which the rabbler makes from thirty-five to forty round trips` hour, secures the best results. Such a hearth can be operated by two operatives Without interference, Will secure the proper metallurgical conditions so as to utilize a minimum of fuel, and will enable the charge to be kept covered as it is being rabbled, thereby reducing the fuel to a minimum and giving a maximum extraction. Theregularity of the rabbling together with the regularity in covering the charge will not oilily secure a regularity of the separation of t e but Will also reduce the fuel required, in

per

that it enables the sulfur content of the ore be caught to be better utilized for heating the charge.

It will thus be seen that the hearth is mechanically operated in so far as the operations can be performed mechanically. The most diflicult and laborious operation, namely, the rabbling operation, is performed mechanically, so that,with a given operating force, the output of a furnace will be very much increased. ,Moreover, it is not necessary for the Workman to come so close to the furnace, as the' leveling can be performed with long handled shovels, andthe danger of poisoning tol the Workman is, therefore, avoided. This poisoning is furthermore practically completely obviated byA the employment of the exhausting hood', which carries off any fumes which may not by the main hood. The provision of the auxiliary hood and provided withan air space between the main hood and the carriage, will not only facilitate the exhaust of the fumes from the hearth, but will also shield the carriage and the -mechanism :thereon against the radiated heat, so as to permit and facilitate lubrication and operation.- By suspending'the carriage so that its'lovver end will be scribed.

rabbling device in Work gray slag and regularity of the smelting,

adapted hood, spaced kfrom the man1 spaced from the base or floor-line, the front of the furnace is workmen.

It is obvious that various changes may be made in the details of construction and manipulation Without departing from the spirit of this invention, and it is, therefore, to be understood that this invention is not to` be limited to the specific details Having thus is claimed is: l

1. A smelting described the invention, what furnace,

left entirely clear for thecomprising, a

s'hown and de- Scotch hearth adapted to receive molten,

metal upon which floats the material to be smelted, a carriage mounted for movement along said hearth, a rabbling device mounted on said carriage and adapted to engage the material on said' hearth, operating means for imparting a step bystep movement to said carriage, and

coperative relation With respect to saidvoperating means, adapted to up the. material on said hearth.

2. A smelting furnace, comprising, a hearth adapted to receive molten metal upon which floats the material to be smelted, a carriage mounted for movement means forV operating said j along said hearth, `a rabbling device mounted on `said carriage, means for moving said rabbling device into and out of the material on said hearth, carriage While said rabbling device is Withdrawn, adapted to Work up the materialon said hearth. l

3. A smelting furnace, Scotch hearth adapted to metal upon which floats the material to be smelted, a carriage mounted for movement along said hearth, a rabbling device mounted on said carriage, means for moving said rabbling device into and out of the material on the hearth, and means imparting a step by step movement to said carriage, adapted to move said carriage While said rabbllng device is withdrawn, and adapted to work up the material on said hearth.

4. A' smelting furnace, comprising, a

comprising, a receive molten and means for moving said Scotch hearth` adapted 'to recelve molten floats the material to be along said hearth, a ralobling device mounted A the material on said hearth, and means for returning said carriage.

6. A smeltingv filrnace, comprising, a

Scotchhearth adapted to receive molten metal upon which floats the material to be adapted to work up smelted, a carriage mounted for movement along said hearth, a rabbling device mounted on said carriage, means for feeding said carriage along sald hearth, means for operating said rahbling device in coperative relation with respect to said feeding means, the material on said hearth, and means for returning said carriage while said rabbling device remains inoperative.l

7. A smelting furnace, comprising, a Scotch hearth adapted to receive molten metal upon which floats the material to be smelted, a carriage mounted for movement along said hearth, a rabbling device mounted on said carriage, means for feeding said carria e alon said hearth, means for operating sai rabbhng device in cooperative relation with respect to said feeding means adapted A. to work up the material on said hearth, and

' metal upon which -9.A smelti g means for imparting a quick return movement to said carriage.

8. A ,smeltingr furnace, comprising, -a Scotch fhearth ada tedto receive molten oats the material to be smelted, aV carriage vmounted for movement along said hearth, a rabbling device mounted on said carriage, means'for feeding said carriage along said hearth, means for operating said rabbling device in coperative relation with respect to said feeding means adapted to work up the material 'on said hearth, and means for automatically stopping saidlcarriage at the end ofits feeding furnace, comprising, a

` Scotch .hearth adapted. to receive molten f along saai-mmh,

metal upon which floats the material to be smelted, a carriage mounted for movement. a rabblng devicemounted on lsaid carriage, means for feeding said car. riage alon said hearth, means for operating said rabbhng device in coperative relation with respect to said feeding means adapted to work up thefmaterial oI said hearth, and

4 means for rendering s aid feeding and operatingmeans inoperative.

10. 'A smelting furnace, comprising,l a Scotch hearth ada tedto receive molten metal upon which oats the material to be smelted, .a carriage mounted :for movement along said hearth, a rabbli-ng device mounte on4 said carriage," means for feeding said smelted, a carriage d smelted, a carriage hearth, and means for stopping said rabf bling device 1n Withdrawn position.

11. A smelting furnace, comprising, a Scotchhearth adapted to receive molten metal upon which ioats the material to be smelted, a carriage mounted for movement along said hearth, a rabbling device mounted on said carriage, means for' feedin said carriage along said hearth, means or operating said ra'b'bling device in cooperative relation with respect to said feeding means, and means for stopping said carriage with. said rabbling device in withdrawn position.

12. A smelting furnace, comprising, a Scotch hearth adapted to receive molten metal upon `Which floats the material to be smelted, a carriage mounted for movement along said hearth, a rabbling device mounted o n said carriage, means for feeding said carriage along said hearth, means for operating said rabbling deviceA in coperativerelation with respect to said feeding 'means adapted to Work up the material on sai hearth, 'means for automaticallyT stopping said carriage at the end of its feeding movement, and manually controlled means for starting said carriage.A l

13. A smelting furnace, comprising, a Scotch hearth adapted to receive molten metal upon which floats the material to be mounted for movement along said hearth, a rabbling device mounted onsaid carriage, means for feeding said carriage along sai erating said ra'bbling device is coperative relation'with respect to said feeding means adapted to work `up the material. on said hearth, means operating automatically at the end of thefeeding-movement forrendering said feeding and operating -means inoperative, and manually controlled lmeans for again rendering said feeding and oper ating means operative.

14. A smelting furnace, comprising, a Scotch hearth adapted to receive molten metal upon which ioats the material to khe smelted, a carriage mounted for movement ,along said hearth, a rabbling device mounted to work up the material on said'hearth, and, l

means for varying the feed.

"15. A' smelting furnace, comprising, a Scotch hearth ada ted to receive molten metal upon which oats the material to be suspended in front of and for movement" along said hearth, a i

' up the material 'on a detachable connection rabbling device-mounted on said carriage, means for feeding said `carriage along said hearth, and means for operating said rabbling device in coperative relation with respect tosaid feeding up the material on said hearth.

A smelting furnace, comprising, a Scotch hearth having an apron extending therealong adapted to receive the molten metal upon which floats the material to be smelted, a carriage suspended above said apron and for movement along said hearth, a rabbling ydevice mounted on said carriage,

means for feeding said carnage along said bling device in cooperative relation. with respect to said feeding means, adapted to work said hearth. smelting furnace, comprising, a Scotch hearth adapted to receive molten metal upon which floats the material to be smelted, a carriage suspended above the hearth base in front ofthe hearth and for movement along the same, arabbling device mountedon said carriage, means for feeding said carriage along said hearth, and means for operating said rabbling device in cooperative relation with respect to said feeding means, adapted to work up the material on said hearth.

18. A smelting furnace, comprising, a Scotch hearth, a carriage mounted for movement along said hearth, a rabbling device mounted on said carriage, means for feeding said carriage along said hearth, means for operating said rabbling device in cooperative relationwith respect to said feed:- ing means adapted to work up the material on said hearth, and a yielding connection between said rabbling device and said operating means.

19. A smelting furnace, comprising, a Scotch hearth adapted to receive Vrnolten metal upon which floats thek material to be smelted, a carriage mounted forvmovement along said hearth, a rabbling device'mounted on said carriage, means for feeding said carriage along said hearth, means for operating said rabbling device in cooperative relation with respect to said feeding means adapted to work-up the material on said hearth, and

bling device and said operating means.

20.. n a smelting furnace, having an ore hearth adapted to receive molten metal upon which fioats the material to be smelted, rabbling means comprising a carriage, means for feeding said carriage step .by step, a rahbling device mounted on said carriage, and means for operating said rabbling device in cooperative relation with respect to said feeding means, adapted 'to work up the material on the hearth.

21. In a smelting, furnace, having an ore hearth adapted to receive molten metal upon means, adapted to work earth, and means for operating said-rab-` between said rab- `fuel, Ia rabbling vment along and 'into said hearth, means forwhich floats the materialto be smelted, rabling means comprising a carriage, means f,

for feeding said carriage step by step, a rabbling devicemounted on said carriage, means for operating said rabbling device in cooperative relation with respect to said feeding means adapted to work up the material on the hearth, and means for imparting a quick return movement to said carriage.

22. In a smelting furnace, having an ore hearth adapted to receive molten metal upon which floats the material to be smelted, rabbling means comprising a carriage, means for feeding said carriage step by step, a rabbling deviceniounted on said carriage, means for operating said rabbling device in cooperative relation with respect to said feeding means adapted to work upl the material on the hearth, and means for imparting a quick return movement to said carriage .with said rabbling device in withdrawn position. v

23. In a smelting furnace, having an ore hearth adapted to receive molten metal upon which floats the material to be smelted, rabbling means comprising a carriage, a rabbling device mounted on said carriage, means for operating said device adapted to work up the material on-the hearth, and a yielding connection between said operating means and said device.

24;. In a smelting furnace, hearth adapted to receive molten metal uponV which floats the material to be smelted, rabling means comprising a carriage, a rahbling device mounted onsaid carriage, means for operating said device adapted to work up thematerial on the hearth, and a detachable connection between said operating means and said de vice.

25. A smelting furnace, comprising, a unitary ore hearth 4adapted to'receive molten metal 'upon which floats the bed. of ore and fuel, a rabbling device mounted for movement along and into said hearth, means for moving lsaid rabbling device back and fortho `along said hearth, and means'for operating said rabbling device, adapted to work up the-.bed in onefdirection along said hearth.

26.,.A smelting' furnace, comprising, a unitary ore hearth adapted to receive molten metal upon-which fioats the' bed -ofore and l device mounted for move- `having anore moving said rabbling device back and Vforth along said hearth, and means for operating said rabbling device, adapted to work up the bed in one direction along said hearth,VA

the length of said hearth being proportioned to correspond to the movement of said rabbling device therealong.

27. A smelting furnace, unitaryv ore hearth adapted to metal upon which floats the fuel, a rabbling device mounted formovecomprising, a recelve molten rbed of ore and .i

thebed in one direction ment along and into said hearth, means for `moving said rabbling'device back and lforth along said hearth, and means for operating said rabblingdevice, adapted to Work up the bed in one direction along ,said hearth, the length of said hearth and the movement of said rabbling device therealong being proportioned to correspond to the period'f smelting of the ore added to the hearth.

28. A smelting furnace, comprising, a unitary ore hearth adapted to receive molten metal upon which floats the bed of ore and fuel, a rabbling device mounted for movement along and into said hearth, means for moving said rabbling device back and forth along said hearth, and means for operating said rabbling device, adapted to Workl up along saidhearth, with an intervening period of rest sufficient to permit smelting of the ore added to the hearth.

29. A' smelting furnace, comprising, a

unitary ore hearth adapted to receive molten i metal upon Which'floats the bed of ore and fuel, a rab'bling device mounted for movement along and into said hearth, means for moving said rabbling device back and forth along said hearth, and means for operating said rabbling device, adapted to work up the bed progressively from one end ofthe hearth to the other` end thereof.

30. A smelting furnace, comprising, a unitary ore hearth adapted to receive molten metal upon which floats the bed of ore and fuel, a rabbling device mounted for movement along and into said hearth, means for moving said rabbling device back and forth along said hearth, and means for operating said rabbling device, adapted to work up the bed progressively from one end of the hearth to the other end thereof, with an intervening period of rest for each portion of the bed sufficient to permit smelting of that portion.

31. A smelting furnace, comprising, a unitary ore hearth having a basin .ada ted to receive molten metal upon which oats the bed of ore and fuel, a rabbling. device mounted for movement along and into said hearth, means for moving said rabbling device back and forth along said hearth, 4and means for operating said rabbling device,

adapted to Work up the bed in one direction along said hearth.

'32. 'A smelting unitary ore hearth adapted to receivemolten metal upon Which floats the bed of ore and fuel, arabbling device mounted for movement along and into said hearth, means for moving said rabbling device back and forth along said hearth, and means for operating said rabbling device While at rest in a direction along said hearth, adapted to Work up the bed. v

33. A smelting furnace, comprising, a unitary ore hearth adapted to receive molten furnace, comprising, a'

metal upon which floats the bed of ore and fuel, a rabbling device mounted for movement along and into said hearth, means for moving said rabbling step by step along said hearth, and means for operating said rabbling device While at rest in a direction long said hearth, adapted to Work up the 34. A smelting furnace, comprising, a unitary ore hearth adapted to receive molten metal upon Which floats the bed of ore and fuel, a rabbling device mounted for movement along and into said hearth, means for moving said rabbling device back and forth along said hearth, and means for operating said rabbling device,

travel in one ldirection but While at rest in during its period of a direction along said hearth, adapted to work up the bed in one direction along said' In testimony whereof I affix my signature this 18 day of March, 1916. A WILLIAM E. ruivvNAM.

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