US3127338A - mantovanello etal - Google Patents

Description

Mar h 3 1964 e. MANTOVANELLO ETAL 3,127,333

SUSPENSION OF ANODIC CASINGS IN CELLS FOR THE UCTION OF ALUMINUM ELECTROLYTIC PROD Filed March 23, 1959 4 Sheets-Sheet l March 31, 1964 cs. MANTOVANELLO ETAL 3,127,338

SUSPENSION OF ANODIC CASINGS IN CELLS FOR THE ELECTROLYTIC PRODUCTION OF ALUMINUM Filed March 23, 1959 4 Sheets-Sheet 2 FIG.5

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SUSPENSION 0F ANODIC CASINGS IN CELLS FOR THE ELECTROLYTIC PRODUCTION OF ALUMINUM Filed March 25, 1959 4 Sheets-Sheet 3 Z0 Z4 /X ,y f/ I 54 M ra a H L, 9 .Z& 4 244, F|G.8 1'0 FIG.9 25 if 25 #25 24x March 31, 1 4 e MANTOVANELLO ETAL 7,

SUSPENSION OF ANODIC CASINGS IN' CELLS FOR THE ELECTROLYTIC PRODUCTION OF ALUMINUM Filed March 23, 1959 FIG. IO

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4 Sheets-Sheet 4 United States Patent SUSPENSIQN 0F ANUDIC CASENGS IN CELLS FOR THE ELECTROLYTIC PRQDUCTIGN OF ALUMINUM Giovanni Mantovanello, Eolzano, and Silverio Bruni, Milan, Italy, assignors to Montecatini Societa Generals: per llndustria Mineraria c Chimica, Milan, Italy Filed Mar. 23, 1959, Ser. No. 801,266 Claims priority, application Italy Mar. 25, 1958 1 Claim. (ill. 2tl4--225) The present invention relates to a new type of suspension of the anodic casing for self-baking electrodes in cells for the electrolytic production of aluminum.

In particular this is an improvement to the recent types of electrolytic cells for the production of aluminum which are fitted with self-baking electrodes, e.g. of the Soederberg-Montecatini type, provided with vertical iron contact rods for feeding the electric current to the anode, and includes the types described in copending applications Serial No. 480,509, filed January 7, 1955 now Patent No. 3,029,194; Serial No. 551,679, filed December 7, 1955 now Patent No. 2,938,843; and Serial No. 587,985, filed May 29, 1956 now Patent No. 2,952,592, all assigned to the assignee of the present application.

The suspension system claimed herein can be applied to anodes having a circular or rectangular cross section as well as to those having a rectangular cross section with rounded short sides. In such a suspension system, the contact rods are firmly anchored to the baked portion of the anode and, therefore, exert also the function of a suspension member. In the store-mentioned types of cells the vertical iron contact rods are connected by suitable clamps with the anodic beam, the ends of which are supported by vertical screw jacks which render possible the vertical regulation of the anode.

The anodic beam of the electrolytic cell comprises one or more rigidly connected metallic beams. In the specific examples disclosed in the present specification reference is made to an anodic beam comprising two elements. Obviously the scope of the present invention includes also cells having one beam element or more than two beam elements. Hence the generic term anodic beam is used herein without being limited to any particular number of elements.

The anode of the cell is contained in a sheet-iron casing, suitably reinforced by means of iron sections and destined to contain the crude electrodic paste and to protect the half-baked and baked portions against atmosphreic oxidation. The anodic casing in general is terminated by a small anodic gas collecting ring for collecting the liberated anodic gas and the products formed by distillation of the pitch used as a binder for the anodic paste.

During normal running of the electrolytic cell the anodic casing should cover the electrode to the greatest extent possible without coming too close to the molten electrolytic bath, in order to avoid any possibility that iron may pollute the bath and, therefore, pollute the aluminum produced.

To achieve these ends, the anodic casing must remain at a predetermined and constant distance from the bath while the anode must be lowered regularly as carbon is continuously burnt by the oxygen developed at the anode from the electrolysis of alumina in the bath.

The anode therefore slides Within the casing which remains in a stationary position.

For this reason, in cells as made heretofore the casing as well as the contact rods in general have not been connected directly 'with the anodic beam. With the prior systems as used heretofore, the casing is usually connected with a special independent beam resting on supports con- 3,127,338 Patented Mar. 31, 1964 nected with the ground. The casing is adjusted, by means of screw jacks or the like, at the desired distance from the bath, which distance remains constant in practice, and the electrode, pushed by the anodic beam through the contact rods, slides gradually down through the casing. 'In these prior devices the anodic beam is controlled by the vertical screw jacks as the electrolytic combustion of the baked anode paste proceeds.

The suspension of the anodic casing on an independent supporting beam involves structural complications which all lead to the need for increased horizontal and vertical space requirements for the anode, thus rendering more ditficult the accommodation of devices for mechanizing the various operations for conducting the cell, such as, e.g. mechanized charging of the anode paste and of the alumina, tapping of the aluminum produced, mechanized breaking of the crust. The necessity of mechanizing those operations is particularly felt in high amperage cells, e.g. of 100 ha. and more.

It is therefore an object of the present invention to provide an improved type of suspension for the anodic casing of an aluminum electrolytic cell so as to maintain the anodic casing at a constant distance from the electrolytic bath, while permitting the anode to be regularly lowered as necessary.

It is a further object of the invention to provide an improved type of suspension for the anodic casing of an aluminum electrolytic cell, which suspension is structurally simple in construction and which requires a minimum of space, thus rendering possible the automatic and mechanized charging of anode paste into the cell.

Still another object of the invention is to provide a type of suspension for the anodic casing of an aluminum electrolytic cell which blocks only downward movement of the casing, but which results in upward movement of the casing when the anode is lifted from a predetermined level.

According to the present invention these and other objects are achieved by connecting the casing to the anodic beam, to which the contact rods are also secured, by means of a mechanical system having a variance of one degree of freedom and which keeps the casing in a predetermined position while the beam is lowered in order to make up for anode consumption.

In this way the former types of supporting beams expressly destined for and attached to the casing can be dispensed with.

Of course, in both the known means of suspension and in that claimed herein, when the anode is lifted for working needs, such as variation of interpolar distance, the casing, owing to its considerable upward taper, is dragged upwards by the electrode. The guide stays of the casing slide Within their guide holes to permit such upward movement, and blockage of casing movement occurs only for descent.

If, to make up for electrolytic combustion the anode in an apparatus according to the invention, is lowered by the amount by which it was previously raised, the casing returns to its predetermined position.

This connect-ion or suspension according to the invention preferably comprises a mechanical system of which two basic types are described herein; namely a funicular (rope) system and a rigid-lever system; these two types operate on the same general principle though differing in construction.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following escription of specific embodiments and modifications when read in connection with the accompanying drawings in which the same numerals designate the same or corresponding parts throughout the several figures, and in which:

FIG. 1 represents diagrammatically in elevation view one embodiment of the suspension system according to the invention, using ropes, chains or cables;

FIG. 2 represents the embodiment of FIG. 1 in plan view;

FIG. 3 represents diagrammatically in elevation view another embodiment of the suspension system according to the invention, using a rigid lever system;

FIG. 4 represents the embodiment of FIG. 3 in plan view;

FIG. 5 is an enlarged detail of the suspension system of FIGS. 3 and 4;

FIG. 6 represents diagrammatically in elevation view another embodiment of a suspension system using rigid levers;

FIG. 7 is a plan view of the system according to FIG. 6;

FIG. 8 represents diagrammatically in elevation View another modification of a suspension system using rigid levers;

FIG. 9 is a plan view of the system according to FIG. 8;

FIG. 10 is an elevation view of still another embodiment of the suspension system using a rigid lever system;

FIG. 11 is a plan view of the system according to FIG. 10;

FIG. 12 is an end view of the system according to FIG. 10;

FIG. 13 represents diagrammatically a detail of a modification of the embodiment of FIG. 6 in larger scale.

Although the drawings illustrate a type of anode having an elongated rectangular section with rounded shorter sides, it is obvious and should be understood that the present description also is intended to include rectangular or circular anodes.

In FIGS. 1 and 2 is illustrated diagramrnatically a connecting system according to the invention utilizing metallic ropes or chains. The anodic casing 2. is terminated by and is supported at its upper extremity by an angle iron or other type of suitable reinforcing element 2a.

Four sturdy eye brackets 7 are fixedly attached to the upper corners of the casing 2, and the respective ends of four metallic cables or chains 8 are secured to the brackets 7 by means of conventional pivot pins or gudgeons (not illustrated). The four cables or chains 8 respectively pass through four sets of cooperating pairs of sheaves tor pulleys 9, 1d, each sheave being pivoted horizontally on the anodic beam 11, until they reach two horizontal beams 51 to which the other ends of the cables or chains are fixedly secured. The sheaves 10 of each pair 9, Iii are arranged so that each of their working circumferences is placed tangential to a vertical axis passing through the eye brackets 7, while the sheaves 9 are arranged so that each of their working circumierencesis tangential to a vertical axis passing through the upper fastening point 52 of the cable or chain to the beam 11.

The length of the metallic ropes or chains 8 is previously predetermined and adjusted at a value corresponding to the desired position of the anodic casing 2. Then when the anodic beam 11 is lowered, the position of the casing 2 remains fixed, since the length of the rope or chain 8 is constant.

Rigid lever systems according to other embodiments of the invention are illustrated in FIGS. 3 to 13, and

these comprise systems of linked rigid members, which connect the anodic casing 2 with the anodic beam 11 and operate to produce a result similar to the embodiment previously described with respect to FIGS. 1 and 2,

i so that the casing remains stationary when the beam 11 is lowered.

Four structural modifications of such systems of rigid linked members are described and claimed as preferred embodiments of the present invention as follows:

FIGS. 3-5 illustrate diagrammatically, by way of example, one embodiment of the principle of a system for connecting the casing 2 to the beam by means of simple rigid levers, stay rods and struts.

As is best illustrated in FIG. 3, four eye brackets 12 are secured to the four corners of the upper edge of the casing 2. Four stay rods 13 are pivotally attached at 12a to the eye brackets 12. A nut 13a at the opposite and upper extremity of stay rods 113 permits adjustment of the length of stay rods 13. A bushing 13!) is slidably mounted on rod 13 and is provided with a projecting boss. Four triangular levers 14, having respective legs 14a, 14b and 140, are pivotally mounted at 14] for rotating on respective ones of four horizontal journalling pivots 15 which are welded or otherwise secured to the anodic beam 11. The three legs 14a, 14b and Ma of each triangular lever 14 are fixed with respect to each other and at their vertices 14d, 14c and 14 form pivoting means for struts 16, bushings 1312 on stay rods 13 and journals 15, respectively.

Struts 16 are hingedly attached at their lower extremity 17 to a fixed base 17a while at the other end they are pivotally attached to the lower vertex 14d of triangular levers 14. The length of the stay rods 13 is adjustable by threaded nut 13:: so that the vertical position of the anodic casing 2 with respect to beam 11 can be changed as desired.

Rod 13 slides together with nut 13a freely in bushing 13b to which member 14 is articulated at Me.

Thus, nut 13a limits the stroke of rod 13 and consequently of casing 2, only downwardly not upwardly. Therefore, once the position of nut 13a is adjusted, if the anodic beam 11 is lowered, the position of the casing 2 remains substantially unvaried, while a cooperating rotation of the stays 13, struts 16 and triangular levers 14 takes place around their respective pivot joints. If the anodic beam 11 is lowered, bushing 13b abuts against nut 13a, limiting the further lowering of easing 2, and the rods 16 act as struts between triangle 14 and pivot joint 17.

In raising the beam 11 from a lowered position, rod 16 rotates counterclockwise while arm 14a of triangular lever 14 rotates clockwise. Casing 2 is lifted only when the anode is lifted, and then stay rod 13 with nut 13a attached thereto slides upward through bushing 13b. The nut 13a limits only the downward stroke, but not the upward stroke of stay rod 13.

To lift the beam 11, while leaving the anode at a standstill, the current carrying studs are utilized. For this purpose, the current carrying studs should be clamped to the casing and unclamped from the beam 11. If on the contrary the anode is to be lifted, the studs remain clamped to the beam 11 and in that case they are not clamped to the casing.

Example 1 By way of a numerical non-limiting example of actual dimensions, with a lowering of the beam 11 by 400 mm., the anodic casing 2 remains fixed in practice by using a lever system corresponding to that described above in connection with FIGS. 3 and 4, and having the following dimensions.

Triangular lever 14:

Length of arm 14c mm 600 Length of arm 14b mm 535 Length of arm 14a mm 271.6

Angle between the sides 14a and 14b (i.e. be-

tween the sides 535/ 271.6 mm.) degrees Length of strut 16 mm 1330 Length of stay 13 mm 500 Obviously, the anodic casing 2 can also be kept fixed in practice by adopting other actual dimensions of the struts 16, stays 13 and triangular levers 14. For strokes or movements of the anodic beam 11 greater than 400 mm., the entire system can be re-dimensioned conveniently to suit the particular requirements.

FIGS. 6 and 7 illustrate a modification of the embodiment of the suspension system in which the connection from the casing to the anodic beam is by means of double rigid levers, rather than single triangular levers as in the embodiment of FIGS. 3-5.

The system of FIGS. 6 and 7 is somewhat similar to the preceding one illustrated in FIGS. 35, except that in lieu of the single triangular levers 14, there is provided an assembly of two bell crank levers 18 and 19, connected to each other by a linking lever 29. The bell crank levers 18 and 19 are pivotally attached at 21 and 22 to the anodic beam 11. As in the case with the embodiment according to FIGS. 3-5, the connection to the casing 2 is completed by stay rods 13 and a bushing (not illustrated) corresponding to bushing 13b. The connection to the fixed base 17:: is completed by struts 16 pivoted at 17. The length of the stay rods 13 is adjustable by means of a nut 1301 so that once adjusted the anodic casing 2 remains in the desired position as the beam 11 is lowered. As the anodic beam 11 is lowered, the casing 2 remains at a standstill because of the fact that the individual components of the lever system cooperate with each other so as to displace the stays 13, slidable in bushing 13b, in a direction oppo site to the lowering direction movement of the anodic beam.

Example 2 By way of a numerical non-limiting example of actual dimensions, with a system according to FIGS. 6 and 7, and for strokes of the anodic beam 11 in the range of, for example, 400 mm., the casing 2 remains fixed in practice with a system of levers having the following dimensions:

Length of struts 16 mm 1061 Length of links 20 mm 385 Length of stay 13 mm 500 Bell crank lever 19345 x 250 mm., angle 8040 Bell crank lever 13250 x 355 mm., angle 90 It should be obvious that other dimensions of the elements of this system can also be used to keep the casing 2 at a standstill in practice. Also, with greater strokes of the anodic beam 11, the system can be re-dimensioned accordingly to suit the conditions.

The embodiment according to FIGS. 8 and 9 is particularly suitable for anodes of great length, and comprises two pairs of stays 28, 29 connected to the beam 11 by means of a bell crank lever 23 and a linking lever 26.

The assembly of this embodiment comprises a strut 16, one end of which is hingedly pivoted on a fixed base 1711 at 17, and the other end is pivotally connected with an angular or bell crank lever 23 which can rotate on a pivot 24 fixedly attached to anodic beam 11. The other end of lever 23 is slidingly connected by means of a bushing (similar to 13b) to the stay rod 28. Stay rod 28 is pivotally hinged to casing 2 at 28a, and another pair of stay rods 29 are similarly hinged at 2% to the anodic casing. A horizontal stay rod 25 joins the respective bushings 13b (not shown in FIG. 8) located on each respective pair of stay rods 28, 29, and a lever arm 26 joins the slidable bushing of rod 29 to a pivot journal 27 which is fixedly attached to beam 11.

The four pairs of stays 28, 29 complete the connection between levers 23, 26 and the casing 2. In this embodiment the casing is supported at eight points, four points being distributed on each side (28a, 29a, 29a, 28a), and the distance between these connecting points are approximately the same on each of the two opposite longitudinal sides along the upper edge 30 of casing 2.

The suspension system illustrated in FIGS. -12 supports the casing from the anodic beam 11 by means of a system of rigid levers and stiff transmission members which are somewhat analogous in principle to the preceding embodiments, but operates in planes which are perpendicular to the two anodic beams instead of in planes parallel thereto, as in the preceding embodiments.

In this embodiment the assembly comprises four struts 16, each having one end hinged to a fixed base 17a at 17, and the other end of each lever 16 is pivotally attached to levers 32 (FIGS. l1, 12). Each of the levers 32 is fixedly secured, such as by a key, to the outwardly extending terminal portion of a respective bar 31. Bars 31 are pivotally journalled in supports 34 which are fixedly attached to the anodic beam 11. The inwardly extending end portion of each bar 31 is fixedly secured, such as by a key, to respective levers 33. Stay rods 13' having nuts 13a threaded on their lower extremities, are slidably connected through holes in the upper angles 30 of casing 2. The upper ends of rods 13' are pivotally suspended from the inner extending end portions of bars 31.

The operation of the embodiment of FIGS. 1012 is analogous to that of the previous embodiments, in that if the beam 11 is lowered, the suspension system coacts in such a manner as to leave the casing 2 fixed in a predetermined position.

Any of the types of connection illustrated in FIGS. 1-12 can be applied for suspension of any type of anode, such as rectangular, rectangular with rounded short sides, circular, etc. Depending upon the length of the anode and the distance between the anode and the outer side wall of the electrolytic cell, one or the other of the illustrated suspension systems may be preferable.

The suspension system according to FIGS. 3 and 4 is particularly suitable for rather short anodes which are disposed not too far away from the cell wall. The suspension system illustrated in FIGS. 1 and 2, 6 and 7, and 8 and 9 are best suited for long anodes, which are relatively distant from the side wall of the cell, while the suspension system of FIGS. 3 and 4 is best suited for short anodes close to the cell wall. The suspension system of FIGS. 1012 is well suited for anodes of any type.

By adjusting the nut 13a, the stays 13 or 13' which connect the anodic casing 2 with the respective levers of any of the suspension systems of 1-12 can be adjusted to any suitable length corresponding to the desired position or elevation of the casing 2 or, better to say, by means of the nut 13a it is possible to vary the maximum distance 146-43, that is, the maximum distance between the beam 11 and the casing. Stay rods 28, 29, and 13 and 13 are all similar in this respect. Thus, in a manner analogous to the chain or cable system of FIGS. l-2, the position or" the casing 2 is maintained in position by means of the threadedly adjustable stays 13, 13', 28, and 29.

FIG. 13 illustrates a modification of the suspension system of FIGS. 8 and 9, but is also applicable to any of the suspension systems of FIGS. 312. The end of the lever 23 is pivotally attached to a bushing 13b slidable on rod 28. A pair of sturdy helical springs 35 on each end of the bushing 13b retain the pivoted end of lever 23' and bushing 13b between the upper and lower nuts 13a. Consequently, if the anodic beam 11 is lowered to follow the anode consumption, when the casing 2 is dragged downward, the springs 35 become tensioned or compressed thereby so as to bring the casing 2 slowly again back into the desired position.

It will be obvious to those skilled in the art, upon studying this disclosure, that devices according to our invention can be modified in various respects and hence may be embodied in devices other than as particularly illustrated and described herein, without departing from the essential features of our invention and within the scope of the claim annexed hereto.

We claim:

In an apparatus for recovering metal by electrolysis in a fused bath, including a pot structure constituting a cathode, an anode of the continuous type, a casing for said anode mounted independently of said pot structure for vertical movement relative thereto, a vertically movable suspension beam above said casing, and contact rods suspending said anode from said beam; a suspension system for supporting said anodic casing from said beam and capable of maintaining said casing approximately at a desired constant position of elevation relative to said pot structure during vertical displacements of said anode and of said suspension beam, said system comprising mechanical linking means fixedly attached at one connecting location thereof to said casing and at another connecting location thereof to a fixed location apart from said beam, and guide means fixed to said beam and operably associated with said linking means so as to maintain said constant position of said casing and limit vertical movement of said beam to a maximum predetermined distance equal to the maximum vertical distance between said connecting locations of said linking means, said mechanical 10 prising journal means fixedly attached to said ancdic beam and forming a connection thereon for journalling said lever means at the third pivot point thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,816,861 CasteX Dec. 17, 1957

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