US2464008A - Continuous replenishment of electrodes in electric salt bath structures - Google Patents

Description

March 8, 1949. R. c. UPTON CONTINUOUS REPLENISHMENT OF ELECTRODES IN ELECTRIC SALT BATH STRUCTURES 2 SheetsSheet 2 Filed Oct. 10, 1945 FIG.2.

INVENTOR.

RICHARD C.UPTON Flea.

ATTORNEYS Patented Mar. 8, 1949 am er CONTINUOUS BgRLENISHMl-INT OF ELEC- TRODES IN EL C'I'RIC SALT BATH STRUC- TUBES Richard 0. Upton, has Clemens, Micln, as-

Ilgnor of one-half ..to Commerce Pattern Foundry. & Machine Company, Detroit,

Mich,

a corporation of Michigan Application October 10, 1945, Serial No. 821,462

sou h...

The invention relates to electrically heated molten bath furnaces and the method of operating the same.

It is the primary object of the invention to obtain a method for repairing partially wastedelec;

trodes without interruption of the continuous use of the furnace.

It is a further object to automatically remove oxides from the bath during continued operation of the furnace. With these and other objects in view the invention consists in the construction and method of operation as hereinafter set forth.

In the drawings:

Fig. i is a plan view of the furnace;

Fig. 2 is a vertical section online 2-4, Fig. 1:

Fig. 3 is a cross section on line 3-4, Fig. 1.

In the operation of electrically heated molten bath furnaces, it is diillcult or impossible'to avoid the introduction of oxides into the molten bath.

These have a very detrimental effect both on the furnace in the wasting of the electrodes and upon the work in decarbonizing the same: These oxides are due to many causes among which are the surface contact of the molten bath with the oxygen of the atmosphere and the absorption of oxides from the surface of the work and fixtures.

Where metallic electrodes are used as, for-instance, iron electrodes, these under the high temperature of the bath and the presence of oxides will quite rapidly waste away and where built into the furnace cannot be replaced without disassembling the same.

In view of conditions as above described, I have devised a method of repairing partially wasted metallic electrodes as follows. When the furnace is originally built, the electrodes are set in the refractory material so as to expose only a top surface thereof to the molten bath. The temperature .of this bath such, for instance, as 2300 F., is above the melting point of a high carbon ferrous metal, such as cast iron, but is below the melting point of low carbonsteels. Consequently, by placing cast iron or similar metal in the bath above the exposed surface of a wasted electrode, such metal will melt to flow into intimate contact with and fuse onto said surface. If, however, there are oxides present in the bath. these will eventually reduce the carbon content with the result that the molten metal will solidify and become an integral part of the electrode. Thus, by this method the electrodes may be repaired as frequently as necessary and without interruption in the operation of the furnace.

Oxides which are present in the molten bath 2 maybe removed by reducing the same to the metallic state and heretofore carbon has been used for this purpose. Carbon is, however, of lower specific gravity than the molten bath and would naturally float thereon so as to have burning con tact with the air and only limited surface contact with the bath. If the carbon is submerged, then oxides in contact therewith at bath temperature will b e'reduced to the metallic state and if the mcltina point thereof is higher than the bath temperature. ametaliic scale will be formed covering the carbonsurface. However, as the melting point of ferrous and certain other metals is lowered by increase in carbon content, it is ob- 15 vious that the reduced metal will be in a molten state at bath temperature as long as it is free to absorb carbon. I have made use of this fact to simultaneously reduce the oxide content of the bath and to form molten metal for restoring the electrode, the preferable construction being as follows. A is the refractory lining of the furnace which, as shown, is rectangular and has a bottom A and side walls A. bedded in the bottom A so as to expose only their upper surfaces, these being slightly lower than the surface of said member A. This will leave a shallow well above each electrode. The side walls 13 havethe lower portions B thereof rising flush with the outer surface of each elec- 9 trod but the upper portions 3* of these side walls are inwardly offset to overlap portions of the electrodes. There are also inward projections B at each of the corners for a purpose hereinafter described. The lining A is set within an outer s5 cement wall C-and the electrodes 13 extend out through this wall and are preferably water cooled at their outer ends as is usual. D are carbon rods which ar placed beneaththe projections B and are held thereby against upward movement 40 through the bath. They are also'arranged above the electrodes to extend longitudinally thereof and are inclined (as shown in Fig. 3) due to the placing of the projections B higher on one side than the other. These projections are also preferably undercut to retain the carbon rods from lateral displacement.

With the construction as above described, a molten bath such, for instance, as one formed of barium chloride will be maintained by electrically generated heat at the desired temperature, such as 2300 F. After the furnace has been in use for some time. oxides will be absorbed by the bath but these coming in contact with the carbon rods D will be reduced to the metallic state. Also, sufllcient carbon will be absorbed to lower the melt- The electrodes B are em-' ing point of the metal below the bath temperature. Thus, liquid metal on the surface of the rod D will flow down the same and will finally drop off into the well above the electrode B to fuse to the surface thereof. Here it will be out of contact with the carbon and the reaction of other oxides still in the bath will reduce its carbon content until solidification takes place. Such process will continue automatically until the carbon rod has been largely consumed after which it may be removed and a new rod substituted therefor.

What I claim as my invention is:

1. In the operation of electrically heated molten bath furnaces containing metallic oxides in the bath thereof and having one or more metallic electrodes, the step of placing within the bath a reducing agent for converting said oxides into metal having a fusing point less than bath temperature and in a position where the molten metal will flow into contact with an electrode.

2. In the operation of electrically heated molten bath furnaces containing oxides in the bath thereof and having one or more metallic electrodes, the steps of placing adjacent to an electrode a metal sufficiently high in carbon content to melt at bath temperature and to flow into contact with the surface of said electrode and subsequently reducing by reaction of said oxide the carbon content of the moltenmetal to solidify the same.

3. In the operation of electrically heated molten bath furnaces containing metallic oxides in the bath thereof and having one or more metallic electrodes, the steps of submerging a carbon rod in the molten bath in a position above an electrode to first reduce a portion of said metallic oxides by contact with the surface of said rod and to drop the same in a molten state upon said electrode in fusing contact therewith whereupon further reaction between said oxides and the molten metal will reduce the carbon content of the latter and solidify the same.

4. In an electrically heated molten bath furnace, a refractory container, a molten bath in said container and containing oxides, a metallic electrode, and a carbon rod submerged in said bath and arranged directly above said electrode whereby said metallic oxides contacting with said rod will be reduced into molten metal which is dropped from said rod on said electrode.

5. In an electrically heated molten bath furnace, a refractory container, an electrode located within a recess in the bottom of said container, a molten bath within said container and having oxides therein, and metal having a sufficient carbon content to melt at bath temperature and so located within said container as to flow the molten metal into said recess in fusing contact with said electrode whereby said oxides will reduce the carbon content of said metal to solidify the same.

6. In an electrically heated molten bath furnace, a refractory container having a recess in the bottom thereof, a metallic electrode located within said recess below the top thereof, a molten bath within said container and having metallic oxides therein, a carbon rod, and means for submerging said carbon rod in said bath above said electrode and recess whereby a portion of said metallic oxides will be reduced by contact with said carbon rod and the molten metal resulting therefrom will drop into said recess in contact with said electrode.

7. In an electrically heated molten bath furnace, a refractory container for the molten bath having a side wall undecut in its lower portion, a bottom having a. recess therein which extends partly beneath said undercut side wall, a metallic electrode in said recess, a molten bath in said container and containing metallic oxides, a carbon rod, ledges on said side wall for holding said carbon rod submerged in the molten bath above said recess and electrode and in an inclined position whereby a portion of the oxides in said bath will be reduced by contact with said carbon rod and the molten metal resulting therefrom will drain off said inclined rod into said recess in contact with said electrode.

8. In an electrically heated molten bath furnace, a refractory container, a molten bath in said container containing metallic oxides, a me tallic electrode, and a reducing agent located in said bath above said electrode for converting said oxides into metal having a fusing point less than the bath temperature and depositing the molten metal on said electrode.

RICHARD C. UPTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 971,782 Peterson Oct. 4, 1910 1,069,255 Heroult Aug. 5, 1913 1,373,615 Jacobs Apr. 5, 1921 1,875,787 Wennerstrom Sept. 6, 1932 2,104,530 Sell Jan. 4, 1938 2,248,628 Hopkins July 8, 1941 2,349,678 Rolnick May 23, 1944 2,355,761 Upton Aug. 15, 1944

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