US 3663411 A
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Description (OCR text may contain errors)
May 16, 1972 Filed Oct. Q2, lV/O K. SPRINGER 3,663,411
MOBILE FURNACE MANIPULATOR 7 Sheets-Sheet 1 May 16, 1972 K. SPRINGER 3,663,411
MOBILE FURNACE MANIPULATOR Filed Oct. 22, 1970 7 Sheets-Sheet 3 K. SPRINGER May 16, 1972 MJULLH FURNACE MANIPULATOR 7 Sheets-Sheet 3 Filed Oct. 22, 1970 y 1972 K. SPRINGER 3,563,411
MOBILE FURNACE MANIPULATOR Filed Oct. 22, 1970 7 Sheets-Sheet y 1972 K. SPRINGER MOBILE FURNACE MANIPULATOR 7 Sheets-Sheet 5 Filed Oct. 22, 1970 K. SPRINGER May 16, 1972 MOBILE FURNACE MANIPULATOH 7 Sheets-Sheet 6 Filed Oct. 22, 1970 May 16, 1972 K. SPRINGER MOBILE FURNACE MANIPULATOR 7 Sheets-Sheet 7 Filed Oct. 22, 1970 United States Patent U.S. Cl. 204-243 R 3 Claims ABSTRACT OF THE DISCLOSURE A travelling furnace manipulator for breaking up the slag crust in an aluminum melt electrolysis cell having a cell rim, an anode spaced across the cell from the rim, and a device for feeding alumina to the cell, a chisel device for breaking the crust, first and second scrapping devices arranged respectively in front of and behind the chisel device when looking in the direction of movement of the manipulator, and an arrangement for moving the first scraping device in front of the chisel device so as to pull an alumina cover on the slag in the cell toward the cell rim, and another arrangement for moving the second scraping device behind the chisel device so as to spread the alumina cover in the direction toward the anode.
FIELD OF THE INVENTION The present invention relates to means for breaking up the slag or dross crust covering the molten electrolyte in aluminum melt electrolysis cells. The breaking up of such crusts is effected no longer in a purely manual manner, but by means of manually operable travelling compressed air operable crust breakers. More recently such crust breakers are equipped with a device for feeding the alumina (or oXyde of aluminum) into the cell and represent complete furnace operating apparatus which shall be called furnace manipulators in the ensuing description and claims.
BACKGROUND OF THE INVENTION Mechanically operated travelling crust breakers are known in various forms. Some are mounted on dirigible carriages, others are mounted on movable gantries above the cells, such as one-legged gantry cranes, gantry cranes or travelling cranes.
The alumina or oxyde of aluminum normally resting on the slag crust is usually not evenly distributed and upon breaking of the crust does not get into the electrolyte in optimum amounts, when presently known furnace manipulators are being used. If the amount is too large the bath silts up or becomes muddy, whereas if the amount is too small the yield per unit of electricity deteriorates.
With heretofore known crust breakers the addition of alumina is effected either without consideration of the desirable proportion of alumina in the electrolyte or, after preceding measurement, by introducing an auxiliary electrode into the melt. In the first instance, the alumina content varies to such an extent that an optimum current yield is hardly obtainable. In the second instance, the whole procedure is very cumbersome and complicated. No or too little attention has been paid thus far to the optimum introduction of alumina into the molten electrolyte when using the heretofore known crust breakers and furnace manipulators.
3,663,411 Patented May 16, 1972 BRIEF SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a furnace manipulator which will overcome the above-mentioned disadvantages of the heretofore known devices of this type.
It is a more specific object of the invention to provide a furnace manipulator which will make equal distribution of the alumina over the electrolyte possible and which will yield optimum supply of alumina to the electrolyte.
The furnace manipulator according to the present invention is characterized primarily in that one alumina scratching tool each is provided in front of and behind the crust breaker chisel, when looking in the direction of movement of the manipulator. The alumina cover is, prior to the crust breaker chisel breaking in, pulled back toward the rim of the cell by one alumina scratching tool and is after the penetration of the chisel distributed again over the bath by the other scratching tool. In this way a very uniform alumina cover is achieved and the profitability of the electrolysis operation is considerably increased.
BRIEF DESCRIPTION OF THE DRAWING The invention is illustrated by way of example in the accompanying drawing, in which:
FIG. 1 shows the furnace manipulator according to the present invention in front view, with the cell to be serviced in cross section;
FIG. 2 is a perspective view of the alumina scratching tool or blade;
FIGS. 3 to 7 show the scratching tool or blade in various positions, and more specifically: in FIG. 3 in rest position; in FIG. 4 lowered into the alumina cover and following the removal of the alumina from the surface of the slag crust to be broken up; in FIG. 5 lifted in the vicinity of the cell rim; in FIG. 6 lifted in the vicinity of the anode; and in FIG. 7 lowered into the alumina cover, ready to remove the alumina.
DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Referring now to the drawing in detail, the furnace manipulator shown therein is mounted on a semi-portal or one-legged gantry crane 10 which is on one hand guided and propelled on a crane rail 11 by two carriages 12 and on the other hand is equipped with a non-driven rubber tire carriage 13 running on the floor 100. The two carriages 12 are driven by means of a drive motor 14 via a transmission 15 and 16. Guide rollers are indicated by the reference numeral 17.
FIG. 1 also shows a melt electrolysis cell 18, diagrammatically and in cross section. A detailed showing is not necessary since such cells are very well knownin the art. The drawing is merely intended to illustrate the general arrangement of the crust breaker and of the alumina scratching blades. The pre-baked anodes 19 are connected to a conductor 22 by means of anode rods 20 and an anode lock 21. The cathode connection is effected by the cathode bars 23. By feeding current to the electrolyte layer 24, dissolved in the alumina, the alumina is dissolved, and molten aluminum 25 settles at the bottom of the bath 2 6. The slag crust is designated with the reference numeral 27 and consists of solidified electrolyte and non-dissolved alumina; reference numeral 28 represents the alumina cover.
The furnace manipulator illustrated in the drawing is intended to service two parallel rows of electrolysis cells. A compressor 39 is mounted on the crane bridge 38, to-
gether with a drive motor 40 and an air vessel 41 which serves for supplying the compressed air operable devices.
.Furthermore, there is provided an alumina bin 42 with an inlet 43 and an exhaust filter 44.
The manipulator comprises a crust breaker chisel 75 and one alumina pipe 54 each in front of and behind the chisel. In this way, the alumina can be supplied the electrolyte 24 in both driving directions. The control of the automatic operation of the furnace manipulator, as well as the supply and removal of the alumina, and of the mechanical operating devices is effected by conventional electronic apparatus.
*It is very important to avoid admitting too much alumina into the electrolyte 24 simultaneously with the breaking up of the slag crust 27, thereby causing a very unfavorable operation of the furnace. To this end, the alumina layer in front of the chisel 75 (when looking in the direction of movement) is pulled away toward the rim of the cell and behind the chisel 75 is distributed over the slag crust 27 in the direction toward the anode 19. This is accomplished by means of the device according to the present invention, which consists of two alumina scratching blades 113 (one on each side of the chisel 75), as shown in FIG. 1 and as illustrated in various positions during its operation, in FIGS. 3 to 7.
Each of the two scrapers 113 comprises a scratching blade 114 (see FIG. 2), which in the example shown is pivotally supported on a tilting shaft 115 on the free end of a scratching arm 116. The blade is normally held in operating or working position by return springs 117. Upon meeting resistance during pullback or during spreading of the alumina cover, the scraper blade can resiliently tilt toward the anode or cell rim respectively. Cotter pins 118 prevent the shaft 115 from slipping olf. Arm 116 is being tilted into the working or rest position by the pneumatic arresting cylinders 119, with piston 120 and piston rod 121, by means of a linkage 122.
The pushing movement of the scraper arm 116 is effected by the cylinder 123 with piston 124 and piston rod 125. The arrangement is mounted on a see-saw or sweep 126 and journalled on a shaft 127. Lifting of the scraper from the alumina layer and dipping of the same into the bath again is accomplished by a tilting movement of see-saw 126 controlled by the oscillation cylinder 128 with piston 129 and piston rod 130.
In FIG. 4, the scratching tool is shown after having pulled back the alumina layer. The scraper blade is located at point 131 of the dot-dash path 132. In FIG. 5, the scraper blade 114 is lifted from the alumina layer. The blade is moving from point 131 in the vicinity of the cell rim to point 133 of path 132. This movement is executed by oscillation cylinder 128. In FIG. 6, the scraper blade has carried out the movement from point 133 across the alumina layer to point 134 in the vicinity of the anode. The horizontal movement is carried out by cylinder 123.
FIG. 7 shows the scraper blade 114 when it has been dipped into the alumina cover in the vicinity of the anode. It has been moved from point 134 to point 135. The vertical movement of the scraper blade 114 is effected by oscillation cylinder 128. Finally, the movement of blade 114 from point 135 to point 131 brings about removal of the alumina layer toward the cell rim.
When servicing the end faces of the cells, the scrapers are held in their rest position.
While FIGS. 3 to 7 described above illustrate the operation of the scraping blade 113 in front of the chisel means it is to be understood that the scraping blade 113 behind the chisel means is the same, but wroks in reverse to spread the alumina cover from the cell rim towards the anode.
The alumina fed to the cell is rather cold and will be intermixed with the warm alumina already present in the bath by means of the scrapers described above, thus resulting in an improved operation of the furnace.
From the above, it is apparent that although the invention has been described hereinbefore with respect to a certain specific embodiment thereof, it is evident that many modifications and changes may be made without departing from the spirit of the invention. Accordingly, by the appended claims, We intend to cover all such modifications and changes as fall within the true spirit and scope of this invention.
1. A travelling furance manipulator of the type described, for breaking up the slag crust in an aluminum melt electrolysis cell having a cell rim, anode means spaced across said cell from said rim, and means for feeding alumina to said cell, comprising: chisel means for breaking said crust, first and second scraping means arranged respectively in front of and behind said chisel means when looking in the direction of movement of said manipulator, and means for moving said first scraping means in front of said chisel means so as to pull an alumina cover on the slag in said cell toward said cell rim, and means for moving said second scraping means behind said chisel means so as to spread the alumina cover in the direction toward said anode means.
2. A travelling furnace manipulator according to claim 1, wherein each scraping means comprises a scraping blade, a shaft rotatably supporting said blade, arm means having its free end connected to said shaft, and spring means connected to said scraping blade for maintaining the same in scraping position.
3. A travelling furnace manipulator according to claim 2, which comprises compressed air operable piston and piston rod means connected to said arm means for moving said scraping blade of the respective scraping means in front of and behind said chisel means, for pulling and sperading the alumina cover respectively.
References Cited UNITED STATES PATENTS 3,433,879 3/1969 Striim et al. 204-245 X 3,551,308 12/ 1970 Capitaine et al. 204-246 X FOREIGN PATENTS 126,271 6/1959 U.S.S.R. 204-245 JOHN H. MACK, Primary Examiner D. R. VALENTINE, Assistant Examiner US. Cl. X.R. 2.04-?A5