US2868711A - Electrolytic cell - Google Patents

Description

Jan. 13, 1959 E. H. KARR 6 ELECTROLYTIC CELL Filed Aug. 10, 1955 V 5 Sheets-Sheet 1 FIGURE l /QJ/Z Jan; 13, 1959 E. H. KARR 2,868,711

ELECTROLYTIC CELL File d Aug. 10, 1955 s Sheets-Sheet 2 1 l4 l6 l3 d D J FIGURE 2 FIGURE 3 INVE TOR.

Jan. 13, 1959 v H. KARR 2,868,711

ELECTROLYTIC CELL I Filed Aug. 10, 1955 3 Sheets-Sheet 3 1| 3 5 LAB-1 a. 5 m

I FIGURE 4 (2/;

FIGURE 6 INVENTOR.

United States Patent ELECTROLYTIC CELL Errol H. Karr, Tacoma, Wash, assignor to Pennsalt Chemicals Corporation, a corporation of Pennsylvania Application August 10, 1955, Serial No. 527,546

6 Claims. (Cl.'204274) This invention relates to improvements in electrolytic .cells and more particularly to improvements in electrolytic cells used for making perchlorates.

*One of the objects of the presentinvention is to make a cell of simple construction that is easy to assemble. Another object is to provide a cell utilizing thin platinum or platinum coated tantalum anodes wherein the anodes are securely positioned within the cell and yet readily removable. A further object is to provide yieldable supports for thin anodes to maintain the anodes in alignment and prevent contact between the anodes and cathodes during cell operation. A still further object of the invention is to provide a cell which permits rapid circulation of the electrolyte therethrough and enables maintaining the cathode surface area and the body of the electrolyte at the optimum operating temperatures. These and other objects and advantages of the present invention will be more apparent on studying the following specification and the drawings in which:

Figure 1 is a side view of a preferred form of my electrolytic cell having a section broken away to show a portion of the interior of the cell;

Figure 2 is a top view of the cell cover;

Figure 3 is a top-sectional view of the cell taken along lines AA of Figure 1;

Figure 4 is a cross-sectional view .of thecell taken along lines B-B of Figure 1;

Figure 5 is a detailed view of one of the anode strips prior to assembly with the remainder of the cell; and

Figure 6 is an enlarged cross-sectional view of one set of anode supports taken along lines CC of Figure 3.

The improved electrolytic cell of my prseent invention is suitable for the production of chlorates, perchlorates, persulfates and similar chemicals and is particularly adapted for the production of perchlorates by the electrochemical oxidation of sodium or potassium chlorate to the perchlorate by use of aqueous electrolytes containing sodium chlorate, sodium dichromate, calcium chloride and hydrochloric acid or other suitable acid.

Referring to the drawings, my electrolytic cell comprises an elongated tank 1, preferably of steel, containing a cathode or cathodes 2 and strip anodes 3.

The cathode 2 is in the form of trombone coils formed preferably from steel pipe and so positioned in the cell as to form vertical banks of horizontally disposed pipe sections on each side of the anodes 3, as illustrated in Figure 4. The cathode is maintained in position within the cell and electrically connected to the cell through the use of metal spacers 4 which are welded to the sides and j the electrolyte.

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which serve to support the insulating rods 10, the purpose of which is hereinafter more fully described.

A raised flange 11 is provided on the top of tank 1 for positioning the cover 12 which is formed of an insulating material preferably made from some artificial stone. A suitable material, for example, is a pressed mixture of Portland cement and asbestos sold under the trade name Transite. The cover 12 is provided with longitudinally extending slots 13 through which the anodes 3 are adapted to pass on assembly of the cell. Cover 12 is also provided with an opening for the electrolyte feed pipe 14 and a. gas vent 16. The electrolyte feed pipe 14 preferably extends to the bottom of thecell while the electrolyte overflow pipe 15 located near the top of the tank permits overflow and removal of the electrolyte.

The anodes 3 are suspended from bus bars 17. The bus bars are supported by the cover 12, and rest on insulating spacers 18. The spacers 18 are preferably made of the same material as the cover 12. In order to obtain the proper spacing between the anodes, the bus bars are separated by spacing blocks 19 which may or may not be made of insulating material as desired. The anodes 3 are clamped to the bus bars 17 by flat conducting strips 20 which are secured to the bus bars 17 by means of bolts 21 which pass through holes 22 provided in the upper end of each anode strip.

After the anodes are inserted into the cell, they are prevented from lateral movement by insulating rods 10 which may, for example, be made of glass. The ends of these rods are supported in the nipples 9 which, after insertion of the rods, are covered with caps 23.

The bus bars 17 and cover member 12 are secured to thte cell tank 1 by means of clamps 7, the screw portion 24 of the clamp pressing on insulating blocks 25 which are placed across the bus bars 17.

It is highly desirable for the sake of good electrolytic efficiency that the cell design permit rapid circulation of The best results have been obtained by using anode strips of about .75 to 1.5 inch in width with suflicient spacing to permit rapid circulation of the electrolyte. The tubular cathode along with strip type anodes permits rapid circulation of the electrolyte throughout the electrolyte area.

If solid platinum anodes are used, such as generally employed in the art, the initial cost for equipping an electrolytic cell with anodes is very high. For forming perchlorates electrolytically, platinum is the most satisfactory anode surface. Since it is only the active anode surface that needs to be made of platinum, platinum-clad tantalum anodes serve equally well, providing a substantial saving in the amount of platinum needed. Also by making the main body of the anode of tantalum, more versatility in shape is possible, a feature that can be used in designing the anodes to permit better circulation of the electrolyte. The metal, tantalum, has about the same degree of chemical resistance and electric current carrying capacity as platinum, and is much stronger mechanically. Because of its chemical resistance, only that portion of the tantalum that is submerged in the electrolyte and is to act as the active face of the anode need be covered with platinum.

This results in further savings in the cost of required platinum. In preparing the anodes, the platinum is preferably placed on the tantalum by rolling, and for best economy, it is generally preferred to use no more platinum on the anode than will be used in the operation of the cell. For prolonged periods of operation, it is, therefore, necessary at times to replatinumize the anode surface. For this purpose, it is highly desirable that cells be so constructed that the anodes can be readily removed.

In assembling the cell, the cell cover 12 is first placed on the tank 1. The bus bars 17, with the anodes clamped through the trombone coil cathode.

thereto, are then carefully lowered onto the cell cover, the anodes passing through the slots 13. After the anodes and bus bars are in position, the clamps 7 are attached and the anode supporting rods 10 inserted. In inserting the rods 10, it is easier if a light source is provided outside of the cell at the end of the farthermost pipe nipple. This aids appreciably in inserting the insulating supporting rods 10. After the rods are inserted, the pipe nipples 9 are closed with the caps 23 and the cell is ready for filling with electrolyte.

During operation of the cell, cooling water is circulated The cooling water enters the cathode at 26 and is exhausted from the cathode at 27. Gases are exhausted from the cell through gas vent 16 which is preferably under slight vacuum. Due to this vacuum, air is swept into the cell through the slots 13 in cover 12. The air thus sweeps across the top of the cell before being exhausted through vent 16. This helps keep the cell free of objectionable gases.

Though the cell is most suitable for the production of sodium and potassium perchlorates, particularly in accordance with the process described in my copending application Serial No. 367,765, filed July 13, 1953, and for the preparation of chlorates and other per-compounds generally, the cell may also be used for the preparation of other chemicals if desired. The claims, therefore, are not limited to the use of cells of the present invention for the preparation of any specific chemical.

Having described a specific embodiment of my present invention, I claim:

1. An electrolytic cell comprising a tank for electrolyte, laterally spaced cathode elements within said tank, an anode in the form of a plurality of relatively thin metal strips extending vertically downwardly into said tank between said spaced cathode elements, means for rigidly supporting said anode strips at their upper end, and means provided at the lower end of said anode strips for minimizing lateral movement of said strips and thus preventing contact thereof with said cathode elements, said last-mentioned means comprising a pair of horizontally disposed insulating rods, means loosely supporting said rods in continuous contact with said strips and yieldingly urging them against opposite sides of said strips while permitting them limited lateral movement in response to forces against said strips.

2. An electrolytic cell in accordance with claim 1 in which said anode strips are composed of tantalum provided with a thin film of platinum.

3. An electrolytic cell comprising a tank for electrolyte, laterally spaced cathode elements within said tank, an anode in the form of a plurality of relatively thin metal strips extending vertically downwardly into said tank between said spaced cathode elements, means for rigidly supporting said anode strips at their upper end, and means provided at the lower end of said anode strips for minimizing lateral movement of said strips and thus preventing contact thereof with said cathode elements, said lastmentioned means comprising a pair of horizontally disposed insulating rods resting against said strips on either side thereof and means for supporting said rods comprising members for loosely receiving each pair adjacent their ends, said members having rod bearing surfaces downwardly inclined toward said anode strips whereby said rods rest against said strips by gravity and are free to be slightly displaced laterally on said inclined surfaces in response to forces against said strips.

4. An electrolytic cell in accordance with claim 3 in which said anode strips are composed of tantalum provided with a thin film of platinum.

5. An electrolytic cell in accordance with claim 3 in which said rod supporting members are located on opposite walls of said tank, said members being provided with openings permitting access to said members to permit insertion and withdrawal of said rods without disassembly of the cell, and removable closure means for said openings.

6. An electrolytic cell in accordance with claim 3 in which the rod bearing surfaces of said rod supporting membersare arcuate in shape and inclined toward said anode strips.

References Cited in the file of this patent UNITED STATES PATENTS 1,477,099 Baum Dec. 11, 1923 2,475,157 Schumacher July 5, 1949 FOREIGN PATENTS 173,028 Great Britain Dec. 12, 1921

Claims (1)

1. AN ELECTROLYTIC CELL COMPRISING A TANK FOR ELECTROLYTE, LATERALLY SPACED CATHODE ELEMENTS WITHIN SAID TANK, AN ANODE IN THE FORM OF A PLURALITY OF RELATIVELY THIN METAL STRIPS EXTENDING VERTICALLY DOWNWARDLY INTO SAID TANK BETWEEN SAID SPACED CATHODE ELEMENTS, MEANS FOR RIGIDLY SUPPORTING SAID ANODE STRIPS AT THEIR UPPER END, AND MEANS PROVIDED AT THE LOWER END OF SAID ANODE STRIPS FOR MINIMIZING LATERAL MOVEMENT OF SAID STRIPS AND THUS PREVENTING CONTACT THEREOF WITH SAID CATHODE ELEMENTS, SAID LAST-MENTIONED MEANS COMPRISING A PAIR OF HORIZONTALLY DISPOSED INSULATING RODS, MEANS LOOSELY SUPPORTING SAID RODS IN CONTINUOUS CONTACT WITH SAID STRIPS AND YIELDINGLY URGING THEM AGAINST OPPOSITE SIDES OF SAID STRIPS WHILE PERMITTING THEM LIMITED LATERAL MOVEMENT IN RESPONSE TO FORCES AGAINST SAID STRIPS.

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