US2868710A - Device for supplying current to the bottom of electrolytic furnaces - Google Patents

Description

Jan. 13, 1959 v P. PONTREMOLI DEVICE FOR SUPPLYING CURRENT TO THE BOTTOM OF ELECTROLYTIC FURNACES 2 Sheets-Sheet 1 Filed Nov. 10, 1954 INVENTOR.

Jan. 13, 1959 P. PONTREMOIII 2,868,710

DEVICE FOR SUPPLYING CURRENT TO THE BOTTOM 7 OF ELECTROLYTIC FURNACES 2 Sheets-Sheet 2 Filed NOV. 10, 1954 Fig. 2b

Fig.2c

INVEN TOR.

, 6%. (PM 7 BY United States Patent DEVICE FOR SUPPLYING CURRENT TO THE BOTTOM OF ELECTROLYTIC FURNACES Pio Pontremoli, Milan, Italy, assignor to Montecatini Societa Generale per llndustria Mineraria e Chimica, Milan, Italy, a corporation of Italy Application November 10, 1954-, Serial No. 468,120

Claims priority, application Italy November 17, 1952 Claims. (Cl. 204-243) because the current has the tendency to distribute itself irregularly over the individual areas of the bottom regardless of whether the bottom is composed of carbon blocks or of tamped carbon paste or compound.

A uniform current distribution and density in the cathodic bottom of an aluminum furnace, however, is desirable for attaining optimum durability of the bottom structure itself and for securing most favorable consumption of the anode or anodes above the furnace bottom. The furnace bottom represents a large proportion in cost of the entire furnace; and only by avoiding the occurrence of current concentrations at singular points and thus local overheating of the bottom can optimum life of the bottom and maximum regularity and economy of furnace operation be achieved.

It is an object of my invention, therefore, to improve the current-supply devices so as to secure a virtually perfect uniformity of current density in the furnace bottom without appreciable complication in furnace design and without entailing the increased susceptibility to injurious ingress of airv encountered with past attempts at improving current distribution. It is another, more specific object of my invention, to secure the desired uniformity of cur rent distribution with the aid of a horizontal arrangement of cathode conductors entering from the side into the furnace bottom.

This and more specific objects of my invention as well as the means for achieving them will be apparent from the following description taken in conjunction with the drawings in which;

Figs. la and lb show a longitudinal section and cross section respectively of a furnace bottom portion according to the invention, and Figs. 1c and ld are coordinate. diagrams of current distribution;

Fig. 2a is a longitudinal section through a bottom portion according to another embodiment of the invention, and Figs. 2b and 2c are explanatory diagrams of current distribution curves.

Fig. 3 is a vertical longitudinal section through a furnace embodying the device of Fig. 2a.

In Figs. 1a, 1b and in Fig. 2a, the layer of molten aluminum is denoted by 11, while 12 denotes a portion of the furnace bottom consisting of a block or a tamped mass of carbon material. Embedded in the bottom portion are a cathode conductor 13 of iron and a bus bar 14. According to Fig. la, the bus bar is connected with the cathode conductor in a single central zone of the latter and may form an integral piece together with the conductor. In the embodiment of Fig. 2a, the bus bar 14 is joined with the cathode conductor 13 in two zones longitudinally spaced from each other. Depending upon the length of ice 2 the furnace bottom in the direction of the bus bars, more than two junction zones maybe provided.

If desired, each bus bar 14 and each connecting zone may be electrically insulated from the carbon material of thefurnace bottom, as shown at 17 in Figs. 1a, lb and 2a, to prevent a direct passage oflcurrent from the bus bar to the cathodic bottom. The insulation 17 may consist of a sheet of asbestos, a layer of heat-proof cement, mica or any other insulating material resistant to temperaturesof 800 C. or more.

The current distribution within the carbonaceous furnace bottom above the cathode conductor is in accordance with curves 15 in the diagrams of Figs. 1d and 2c. The current distribution at the contact surface between furnace bottom and molten aluminum is as shown by curve 16 in Figs. 1c and 2b.

As these diagrams show, an excellent uniformity of current distribution and current density is secured and, as mentioned, a further improvement in this respect can be obtained by providing more than two junction zones suitably spaced from each other.

In a cathode and bus bar system according to the invention, the bus bars of the furnace bottom extend all to the side of the bottom so that it is unnecessary to resort to special and cumbersome expedients for securing a reliable sealing against ingress of air.

Fig. 3 illustrates a furnace or cell for production of aluminum, employing the cathode structure 13, 14, 17 of Fig. 2a. At 20 is the conventional anode, usually of carbonaceous material. The anode is ordinarily movably supported, for upward and downward motion, and has iron conductor rods 21', 22 embedded therein.

I claim:

l'. A molten bath furnace for igneous electrolysis of aluminum, comprising a cathodic bottom portion supporting the molten bath and a consumable anode above the bottom portion, thebottom portion comprising a block of carbonaceous material having a horizontal top surface for contact with the aluminum and having a bottom surface and' lateral side surfaces, a cathode conductor of metal fully embedded in said material and extending parallelto said top surface, a bus bar-of metal laterally extending from the outside through one of said side surfaces to within said block and being located beneath said cathode conductor and adjacent to said bottom surface in parallel and spaced relation to said conductor, the bus bar being enclosed in the carbonaceous block at its upper face, the lower face of the bar being exposed along the bottom surface of the block, and connecting means joining said bus bar with said cathode conductor within said bottom portion and extending upwardly between said bar and conductor in spaced relation from the ends of said conductor, said connecting means being integrally formed with said bus bar and conductor, whereby the conductor is supported by the bus bar and the current from said bus bar is uniformly distributed from said cathode conductor through said carbonaceous material to said top surface.

2. A molten bath furnace for igneous electrolysis of aluminum, comprising a cathodic bottom portion supporting the molten bath and a consumable anode above the bottom portion, the bottom portion comprising a block of carbonaceous material having a horizontal top surface for contact with the aluminum and having a bottom surface and lateral side surfaces, a cathode conductor of metal fully embedded in said material and extending parallel to said top surface, a bus bar of metal laterally extending from the outside through one of said side surfaces to within said block and being located beneath said cathode conductor and adjacent to said bottom surface in parallel and spaced relation to said conductor, .the bus bar being enclosed in the carbonaceous block at its upper face, the lower face of the bar being exposed along the bottom surface of the block, and a plurality of connecting sections spaced lengthwise of and joining said bus bar with said cathode conductorwithin said bottom portion and extending upwardly between said bar and conductor in spaced relation from the ends of said conductor, said connecting means being integrally joined with said bus bar and conductor, whereby the conductor is supported by the bus bar and the current from said bus bar is uniformly distributed from said cathode conductor through said carbonaceous material to said top surface.

' 3. A molten bath furnace for igneous electrolysis of aluminum, comprising a cathodic bottom portion supporting the molten bath and a consumable anode above the bottom portion, the bottom portion comprising a block of carbonaceous material having a horizontal top surface for contact with the aluminum and having a bottom surface and lateral side surfaces, a cathode conductor of metal fully embedded in said material and extending parallel to said top surface, a bus bar of metal laterally extending from the outside through one of said side surfaces to within said block and being located beneath said cathode conductor and adjacent to said bottom surface in parallel and spaced relation to said conductor, the bus bar being enclosed in the carbonaceous block at its upper face, the lower face of the bar being exposed along the bottom surface of the block, and connecting means joining said bus bar with said cathode conductor within said bottom portion and extending vertically between said bar and conductor in centrally spaced relation from the ends of said conductor, said connecting means benig integrally joined with said bus bar and conductor, whereby the current from said bus bar is uniformly distributed from said cathode conductor through said carbonaceous material to said top surface.

4. A furnace for igneous electrolysis of a molten bath, comprising a cathodic bottom portion supporting the molten bath and a consumable anode above the bottom portion, the bottom portion comprising a mass of electroconductive material having a top surface for contact with the molten bath and having a bottom surface and lateral side surfaces, a cathode conductor of metal fully embedded in said material and extending parallel to said top surface, a bus bar of metal laterally extending from the outside through one of said side surface to within said mass and being located beneath said cathode conductor and adjacent to said bottom surface in parallel and spaced relation to said conductor, the bus bar being enclosed in the said mass at its upper face, the lower face of the bar being exposed along the bottom surface of the mass, and connecting means joining said bus bar with said cathode conductor within said bottom portion and extending upwardly between'said bar and conductor in symmetrically spaced relation from the ends of said conductor, said connecting means being integrally joined with said bus bar and conductor, whereby the current from said bus bar is uniformly distributed from said cathode conductor through said electroconductive material to said top surface.

5. An electric furnace for molten materials, comprising an electrodic bottom portion supporting the molten material, the bottom portion comprising a mass of electroconductive material having a horizontal top surface for contact with the aluminum and having a bottom surface and lateral side surfaces, a metal conductor fully embedded in said electroconductive material and extending parallel to said top surface, a bus bar of metal laterally extending from the outsidethrough one of said side surfaces to within said mass and being located beneath said conductor and adjacent to said bottom surface in parallel and spaced relation to said conductor, the bus bar being v enclosed in the said mass at its upper face and along the sides, the lower face of the bar being exposed along the bottom surface of the mass, and connecting means joining said bus bar with said conductor within said bottom portion and extending upwardly between said bar and conductor in symmetrically spaced relation from the ends of said conductor, said connecting means being integrally joined with said bus bar and conductor, whereby the conductor is supported by the bus bar and the current from said bus bar is uniformly distributed from said conductor through said carbonaceous material to said topsurface.

References Cited in the file of this patent UNITED STATES PATENTS 2,331,320 Hartzell Oct. 12, 1943 2,528,905 Ollivier Nov. 7, 1950 FOREIGN PATENTS 871,497 France Jan. 17, 1942 1,052,106 France Sept. 23, 1953 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO. 2,868,710 January 13 95 Pio Pontremoli rs in the above numbered It is hereby certified that error appea patent requiring correction and that the said Letters Patent should read as corrected below In the heading to the printed specification, line 8, for the priority date November 17, 1952" read November 17, 1953 ===u Signed and sealed this 21st day of April 195% (SEAL) Attest:

KARL Ho AXLINE ROBERT c. WATSON Conmissioner of Patents Attesting Officer

Claims (1)

1. A MOLTEN BATH FURNACE FOR IGNEOUS ELECTROLYSIS OF ALUMINUM, COMPRISING A CATHODIC BOTTOM PORTION SUPPORTING THE MOLTEN BATH AND A CONSUMABLE ANODE ABOVE THE BOTTOM PORTION, THE BOTTOM PORTION COMPRISING A BLOCK OF CARBONACEOUS MATERIAL HAVING A HORIZONTAL TOP SURFACE FOR CONTACT WITH THE ALUMINUM AND HAVING A BOTTOM SURFACE AND LATERAL SIDE SURFACE, A CATHODE CONDUCTOR OF METAL FULLY EMBEDDED IN SAID MATERIAL AND EXTENDING PARALLEL TO SAID TOP SURFACE, A BUS BAR OF METAL LATERALLY EXTENDING FROM THE OUTSIDE THROUGH ONE OF SAID SIDE SURFACES TO WITHIN SAID BLOCK AND BEING LOCATED BENEATH SAID CATHODE CONDUCTOR AND ADJACENT TO SAID BOTTOM SURFACE IN PARALLEL AND SPACED RELATION TO SAID CONDUCTOR, THE BUS BAR BEING ENCLOSED IN THE CARBONACEOUS BLOCK AT ITS UPPER FACE, THE LOWER FACE OF THE BAR BEING EXPOSED ALONG THE BOTTOM SURFACE OF THE BLOCK, AND CONNECTING MEANS JOINING SAID BUS BAR WITH SAID CATHODE CONDUCTOR WITHIN SAID BOTTOM PORTION AND EXTENDING UPWARDLY BETWEEN SAID BAR AND CONDUCTOR IN SPACED RELATION FROM THE ENDS OF SAID CONDUCTOR, SAID CONNECTING MEANS BEING INTEGRALLY FORMED WITH SAID BUS BAR AND CONDUCTOR, WHEREBY THE CONDUCTOR IS SUPPORTED BY THE BUS BAR AND THE CURRENT FROM SAID BUS BAR IS UNIFORMLY DISTRIBUTED FROM SAID CATHODE CONDUCTOR THROUGH SAID CARBONACEOUS MATERIAL TO SAID TOP SURFACE.

Images