US1402986A - Electrolytic cell and method of operating the same - Google Patents

Description

H. H. WIKLE. ELECTROLYTIC CELL AND METHOD 0F OPERATING THE SAME.

APPLICATION FILED APR-13.1918. RENEWED APR. 4.1921.

.Patented Jan. 10, 1922.

2 SHEETS-SHEET I.

ll w\\\ nnmw H. H. WIKLE. ELECTROLYTIC CELL AND METHGD 0F OPERATING THE SAME.

APPLICATION FILED APR-13,1918, RENEWED APR. 4.1921. v 1,402,986, Patented Jan. 10, 1922.

2 SHEETS-SHEET 2.

UNITED STATES HUGH H. WIXLE, Ol' CHICAGO, ILLINOIS.

ELECTBOLYTIC CELL AND METHOD Ol' OPERATING m lm Specification ot Letters Patent Patented Jan. 110, 1922.

Application `illecl April 13., 1918, Serial Ro. 228,310. Renewed April 4, 1921. Aerial Io. 450,889.

To all whom 'it may concern.'

Be it known that I, HUGH H. WIKLE, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Electrolytic Cells and Method of Operating the Same, of which the y following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a. part of this specification.

My invention relates toan improvement in electrolytic cells and method of operating the same for preparation of oxides and powders of metals and alloys,k

ile the invention is particularly ap licable to the formation of oxides and powders of metals and alloys for use in the manufacture of brushes for dynamos andthe like, I do not intend to limit the invention to such use.

The object of the present invention is to provide an improved electrolytic cell and manner of operating the same to secure oxide of copper or the like or oxide of the metals which may make up an alloy of copper, such as brass, bronze, german silver, etc.

A further object of the invention is an improvement in the manner of securing finely divided or powdered metals or alloys such as b the powders of copper or alloys of copper or the like.

` In the accompanying drawings which form a part of the present specification, I have illustrated diagrammatically one manner in which my invention may be carried out.

Figure 1 is a view partly sectional and partly diagrammatic o an electrolytic vat for carrying out my invention;

Figure 2 is a plan view of the vat;

Figure 3 is a diagram off the connections' for a series of cells; v

Figure 4 is a diagrammatic layouty of a cell and associated mechanism lfor carrying out the invention;

Figure 5 is a diagrammatic view of a furnace for the reduction of the oxide; and Y Figure 6r is a view illustrating the step of mixino' the oxide with a reducing agent such as car on. y

In the manufacture of brushes for electrical machiner particularly brushes ofthe metal and metal graphlte type, it is necessary to secure metal in a finely subdivided state to form the same into a compact mechanical mass formed of a mixture of carbon, preferably `n gra hite form, with the finely divided metal. e present invention aims particularly to secure such finely divlded metal, but it -is apparent to those skilled in the art that thel process is not limited to such use and may be applied whereever a iinely divided oxide of the metal or a powder of the metal is required.

Incidentally I have found that it is possible to treat alloys of' copper in substantially the same manner as pure copper and arrive at the finely sub-divided oxide of the alloy with the same steps and apparatus employed in securing `the oxide or powder of co per.

find also alloy by mixing the proper proportions of the metals either in elementary form or in the form of their oxides and then heating in a reducing atmosphere to the oint of reducing the oxides, or of causing the elementary metals to unite to form a powder of the alloy.

The electrolytic cell which I have devised is particularly applicable to carrying out the above process, but it is not to be limited to such use.

The vat l shown in Figure 1, comprises a ox of wood or other insulating material, provided with a plurality of wooden partitions 2, which extend down into the vat to a oint adjacent the bottom wall 3 of the vat.

that I can secure the powdered etallic electrodes l1-5are mounted on opposite sides of the partitions 2 by means of the bolts or pins 6 which are preferably made of the same material as the electrodes or lates 4 5.

n a vat which I have employed successfully the tank 1 is made approximately 36 feet long by 10 inches wide by 12 inches deep with the partitions reaching down to within 2 inches of the bottom ofV the vat. Any dimensions desired may be employed and the above are given merely for the sake of illustration. The number of cells which are in series depends upon the voltage which is impressed on the cells. Where a voltage of 125 volts direct current is available, the vat should be divided into 100 cells so that the voltage across each cell is approximately l volts. The end electrodes 7 and 8 are connected through a reversing switch 9 to a suitable source of current l0. The reversing switch 9 mayabe manually operated llO or maybe automatically operated, as by means of the mechanism which I have illustrated. The movable contacts 11-12 are mounted on a rock shaft 13. The rock shaft -13 is connected to a toggle mechanism 14 which is adaptedto be periodically thrown from one side to the other by means of a spring 15 and the slotted link 16 which slotted link is controlled by the constantly rotating cam 17.

The bottom of the vat is connected by a pipe 18 through a valve 19 to a filter 20. This filter comprises an open sided box having a screen'or filter, preferably a piece of fine cloth 21 on the bottom of the box for filtering out the oxide which is precipitated in the vat 1. The liquid which passes through the filter is collected in a tank 22 from whence it is pumped by means of the pump 23 and the pipe 24 back to the vat 1. The pipe 24 is provided with a suitable valve 25.

The operation of the mechanism thus far described is as Afollows:

Assuming that the parts are in the condition shown in Figure 1 and that the vat l is filled, or substantially lled with an electrolyte of'sodium chloride (NaCl), current passes from-the source and through the cells in series, electrolyzing the said solution of sodium chloride, causing the sodium atoms to collect at the cathode and the chlorine atoms to pass to the anode of each cell. This action may be represented by the following equation: NaCl:Na-l-Cl.

As explained, the sodium ions collect at the cathode and there combine with the water of the solution, according to the following equation: 2Na-{2II2O'=2NaOH-|H2.

The chlorine ions which have migrated to the anode unite with the metal of the anode to form a chloride or chlorides of the same. Assuming that the electrode is of copper, the following equation takes place:

The current density in the vat is maintained at such a value that heating of the electrolyte occurs. Heating of the cupric chloride in the presence of cppper causes the following reaction: CuCl2-l-Cuz2CuCl.

Cuprous oxide is then formed by hydrolyzing the cuprous chloride with hot water in accorda-nce with the following equation: 2CuCl-}II2O -Cu2O}-2HCL Y The cuprous oxide forms a very fine heavy precipitate of red color, which precipitate settles to the bottom of the vat in each cell and may there be drawn out. The recombination of the hydrochloric acid with the sodium hydroxide makes the process continuous, as can be seen from thefollowingequation: HCl-l-NaOHzNaCH-HZO.

Whereas certain other oxides or chlorides or chemical combinations of the elements above set out may occur, I find that on the whole the hction is such as to conform with the above ractions .which I believe to occur. The cuprous oxide which is formed inthe electrolyte is so finely sub-divided that it remains partly in suspension and can be drawn off by way of the pipe 18 into the filter 20, where the oxide is separated from the li uid and the liquid is returned to the vat.- he process of removing and filtering out the oxide may be intermittent or continuous as desired. The cuprous oxide is preferably washed to remove the salt or hydroxide of the solution and may then be dried if desired or used in the wet condition, as will be described later.

In order to carry out the complete process it is necessary to get the sodium hydroxide and the hydrochloric acid into intimate contact with each other so that the process may be carried onas effectively and economically as possible. In order to secure this result in the most advantageous manner I have provided the reversing switch 9, which periodically reverses the polarity ot' the electrodes so that current flows in the opposite direction and the reactions can occur more easily and efficiently. I have found that the reversal of current at periods of one hour is effective in securing the desired action.

In order to obtain the maximum eiiiciency the electrolyte should always be kept at the point of'saturation, but no free salt (sodium chloride) shouldvbe introduced into the vat.

The electrolyte should be kept at a temperature of not lower than deg. C. and not higher than 90 deg. C'. This temperature may be maintained by the proper current strength through the electrolyte. The voltage across the vat should not exceed 1% volts. A current density of approximately 144 amps. per sq. tt. ot anode surface gives about as great an output as can be secured without boiling the electrolyte and secures the best eEect.

I have discovered that not only does copper pass through the reactions above indicated, but alloys of copper may successfully be reduced to the oxide form by the same process. That is to say, I have found that brass and bronze may be reduced from the solid metallic condition to a condition of an oxide of the alloy, which oxide may be again reduced to the metal, producing a iinely divided powder of the alloy.

The exact chemical reactions which occur I am unable to state. It is sufficient to say, however, thatobserving the above rules, I

am able to use brass electrodes in the'electrolytic vat or cells above described and secure an oxide or oxides which, when passed through the reducing stage which I shall presently describe, produce finely divided particles of the alloy without a change in the proportions or the property of the alloy.

subjecting the same to heat in 4a reducing.

atmosphere of about 1500 deg. F.

The oxide is mixed with an excess of carbon and heated in a closed chamber` a reduc' atmosphere where the material is employ for brushes. Tothis end the oxide either of copper or of the allo is mixed with the pro r proportion of car n, preferably in grap te form, to form a grap composition suitable for the material of the brush. This may be done as illustrated in Figure 6 by stirring thetwo materials in the mixing vessel 27.

I have found it an advantage to mix the oxide in the wet condition with the graihite so that there is less danger from the yin dust and less inconvenience. The batch of oxide and gra hite is then placed in the furnace 28, as srliown at 29 in Figure 5 and sub'ected to heat, while a current of gas suc as hydrogen or city gas is passed through the furnace from the main 30.

I have found that the resulting material consists of a mixture of graphite and the metal or'alloy in very iinel sub-divided condition, the metal or alloy ing suitably annealed andbeing preferably in the form of crystals. The metal is ofsuch ineness that it would readily pass through a 200 mesh screen and is in ideal condition to form a homogeneous brush. If desired the metal brush produced may be employedv for any other purpose.

I have also found that where powdered metals or their oxides are mixed in proper iproportions to form an alloy and are then re in a reducing atmosphere, that the resultant mass consists of iinelydlvided ains of the alloy. This is of considerab e advantage in case it is desired to obtain a powder of an alloy and a powder or an oxide of one of the metals is obtainable or is already secured. This permits of powders or oxides of the metals being secured from various sources and makin up a powder of the alloy without going t rough the stage of melting the metals into a mass of alloys.

Due to the extreme ineness of the metal or alloy when produced as above described,

there is no noticeable tendency of the metal and the graphite to segregate and a very su erior article results.

he electrolytic process may be carried out in a single cell, as illustrated in Figure 4.

The separate cells may be employed in seriles or in multiple, or in combination of bot s In Figure 3 I have illustrated one manner in which a grou of 100 cells may be connected for suitab e handling. The cells are arranged in groups of ten and provided particular ou so that these cells may ite metal with switches so that any group may be cut out for the removing of oxide and refilling the cell. A series of switches S are provided for cutting out by short circuiting, ma; emptied in 'vi ually for filter' out the oxide and for rechar ing with t e filtered liquid or fresh liquid e ectrolyte. Otherwise the operation of the cells in this arr ent is the same as described in connection with Figures 1-2.

I have found that by keeping the electrol cold the nature of the precipitate is c anged to the extent that the precipitate consists of a complex cuprous hydroxide which Ymay be drawn off and treated in substantially the manner above described to reduce the same to the metal, or to combine g into an alloy. The hydroxide is reducible 1n substantially the same manner as the oxide. -I do not consider this a departure ta us manner of practicin the same.

ead of'sodium chlori e, other alka1ihalide salts may be employed.

I do not intend to be limited to the precise details of construction and the precise ste s of operation above described.

claim:

from my invention but only a less advan 1. In a cell, a pair of electrodes, an elec` trolyte comprising a halide which under electrolysis releases a halogen for attacking said electrodes, a source o current for the electrodes and means for versing the polarity of said electrodes.

2. In a cell a pair of electrodes made of a metal comprising copper, an electrolyte comprising a solution of sodium chloride, a source of current for said electrodes and a reversing switch for periodically reversing the polarity of the electrodes.

3. The method of operating an electrolytic cell having electrodes of similarl material which consists in periodically reversing the polarity of the electrodes, and maintaining the current density at such a value as to heat the' electrolyte.

4. The method of precipitatingan oxide of a metal, which consists in passing current from an electrode formed of the metal, through an electrolyte consisting of a saturated solution of common salt to an electrode of the same metal and simultaneously periodically re' generating heat in the electrolyte with said of the metal chloride to an electrode of the same metal then heating the solution and periodically reversing the polarity of the electrodes.

7. The method of precipitating an oxide of a metal, which consists in decomposing a soluble chloride in the presence of the metal to form a chloride of the metal, then heatin the chloride in the presence of the metal and water to precipitate an oxide of the metal.

8. A method of producing cuprous oxide, which comprises electrolyzing a solution of salt with copper electrodes to form copper chloride and then heating the electrolyte containing the copper chloride to hydrolyze the copper chloride and precipitate the copper thereof as cuprous oxide.

9. The method of operating a cell for precipitating oxides of a metal, which consists in passing a curent from a metal electrode through an electrolyte consisting of a soluble chloride to an electrode of the `same metal with suicient current density to heat the electrolyte to between 7 OV deg. C and 90 deg. C. I

10..The method of operating a cell for precipitating oxides of a metal, which consists in passing a current from a metal electrode through an electrolyte comprising a soluble chloride to an electrode of the same metal with sucient current densit to heat the electrolyte to between 70 deg. and 90 deg. C., and periodically reversing the direction of current iiow.

11. The method of operating an electrolytic cell which consists in periodically reversing the current flow through the c'ell.

12. The method of operating an electrolytic c ell for the production of metallic oxide in Hocculent or precipitated form suitable for reduction to a minority subdivided metallic powder, which consists of passing a current from a suitable metallic electrode containing the metal to be precipitated through an electrolyte consisting of a halide of a metal of the alkali group to a second electrode also containing the metal to he precipitated and periodically reversing the ow of current through said electrode and electrolyte.

In witness whereof I hereunto subscribe my name this 4th day HUG H.` WIKLE.

of A ril,`A. D. 1918.

Images