US1726236A - Electrochemical treatment of saline and alkaline solutions - Google Patents

Description

Aug. 27, 1929.

H. C. PARKER ELECTRO CHEMICAL TREATMENT OF SALINE AND ALKALINE SOLUTIONS Filed Sept. 26, 1928 Patented Aug. 27, 1929.

UNITED STATES HERSCHEL C. PARKER, OF LOS ANGELES', CALIFORNIA.

ELECTROCHEMICAL. TREATMENT OF SALINE AND ALKALINE SOLUTIONS.

Application filed September 26, 1928. Serial No. 308,505.

My invention relates to an electro-chemical treatment of saline and alkaline solutions and apparatus therefor.

In certain lakes brines and alkaline and 6 saline deposits, comprising mixtures in varying proportions of the chlorides and carbonates of either sodium or potassium or both frequently occur. To take a typical case of a natural solution, Mono Lake, California,

carries approximately 2 of sodium chlo ride and 2% of sodium carbonate with very small amounts of other salts. The brine obtained from Searles Lake, California, contains approximately 16% of potassium ch10- ride, 7% borax, 10% of sodium chloride, 8% sodium carbonate, 2% sodium sulphate. It is an object of this invention to subject the solutions just mentioned or similar solutions to an electro-chemical process using 2 special electrodes and other conditions so that I obtain as the principal products ochre (ferric oxide) and sodium carbonate in a simple and economic manner.

My process uses iron as the anode, which 2 during the process is converted to ferrous hydroxide. The ferrous hydroxide because of its tendency to float is decanted from the upper portion of the electrolyte while the sodium bicarbonate is removed from the anode where it collects, and because of its greater specific gravity settles at the bottom of the electrolyte whence it may be removed by gravity.

With the above and other objects in view, as which will appear as the description pro ceeds, my invention consists of the steps of the process and the apparatus used for carrying out said process hereinafter shown and described.

In the accompanying drawings which form a part of this specification I have illustrated the apparatus for carrying out my process, in which:

Figure 1 is a vertical cross section of the apparatus;

Fig. 2 is a sectional view on line 2-2 of Fig. 1;

Fig. 3 is a plan detail view of the anode shown in Fig. 1; Fig. 4 is a detail view of the vibrator;

Fig. 5 is a cross sectional view of the apparatus shown in Fig. 1, illustrating a modified form of the anode;

Fig. 6 is a view similar to Fig. 5, showing 85 still another form of anode;

Referring to the drawings, 1 indicates an electrolytic cell made of suitable material unaffected by the electrolytic process. Vertically disposed within the cell and preferably in the middle thereof is an anode 2. At opposite ends of the cell 1 and spaced equidistantly from the anode 2, are two cathodes 3. The cathodes 3 are connected by conductors 4L and 5 leading to a suitable source of electric energy such as indicated at 6. A valve controlled inlet pipe 7 conducts the saline solution to be treated into the cell 1. An overflow pipe 8 leads from cell 1 to a filter ress (not shown) of any suitable or pre erred construction. The anode 2 is made of iron and consists of a plurality of vertical plates 12 radially arranged and secured to a vertical, non-corrodible shaft 13 such as nickel steel rotated by pulley 14 from any suitable source of power not shown. A conductor 15 leads from the source of electric energy 6 to a brush 16 contacting with the shaft 13. The cathodes 3 are made of any suitable material preferably carbon rods 3' unaffected by the electrolyte.

A suitable vibrating device; 17 consisting of a toothed wheel 25 fast on shaft 13 and a spring pressed pawl 26, is provided to vibrate the shaft 13 and the anode 2 carried thereby, for the purpose of dislodging and shaking off the material collected on said anode. The cell 1 is preferably provided with the bottom inclined toward the middle as indicated at 1', with a valve controlled outlet 18 arranged just below the anode 2.

In place of the anode 2 shown in Fig. 1 a different form illustrated in Fig. 5 may be used. The same consists of a container 19 openat thetop and filled with scrapiron 20. The shaft 13 is suitably secured to the bottom of the container 19. The wall of the container 19 is provided with perforations 19'. The material. used -for making the container is a non-conductor preferably wood or other material unaffected by the electrolyte.

In Fig. 6 another modification of the anode is illustrated. Here a wooden drum 21 mounted on a horizontal shaft 22 and provided with a 'door 23 for the insertion of the scrap iron-20 is used, said drum being provided with perforations 21'. The horizontal shaft 22 projects through the side wall of cell 1 and is driven by a pulley 24'. No vibrator is necessary in this eonstruc-' tion of the anode, since the tumbling about of the scrap iron will dislodge the sodium bicarbonate.

.Assuming that a saline solution containing sodium carbonate and sodium chloride taken from Mono Lake, California, is to be treated, the same is conveyed into cell 1 and a; current of about 6 volts with a current strength of 15 amperes is used. The reactions produced by the electrolysis are somewhat complicated and are believed to be as follows:

2. Fe+Cl =FeCl 3. FeCl 2NaOH= Fe (OH) 2 2NaCl 4. 2NaOH+ Cl =NaCl NaClO H 0 5. Na CO 2H O 2NaOH H CO 3 6. Na CO H 00 2NaHCO The above reactions are not to be understood to take place consecutively but take place simultaneously, at least in part, some of them taking place at the cathode and some at the anode. These equations are simply stated to aid in' the explanation as to what most likely takes place in the electrolytic treatment of the solution.

The sodium chloride will be decomposed into the sodium ions and chlorine ions. The sodium ions at the carbon cathodes 3 will decompose the water. forming sodium hydroxide and hydrogen, the latter gas bubbling to the surface of the electrolyte. The chlorine ions at the iron anode will form sodium chloride and ferrous chloride and the latter reacting with the sodium hydroxide will form ferrous hydroxide and sodium chloride. Consequently no chlorine will, under the conditions stated, form at the anode and ascend to the surface but will react with the sodium hydroxide and iron.

The chlorine to some extent will also com- & bine with the sodium hydroxide and form settles to the bottom whence it may be removed through the outlet 18. The process may be carried on continuously by controlling the inlet 7 and outlets 8 and 18.

The iron hydroxide forms a fiocculent precipitate which rises to the top and is taken out through. the outlet 8. The ferrous hydroxide is recovered in a filter press and is subsequently dried and converted into ferric oxide by oxidation and forms an excellent pigment suitable for paints and the like.

The sodium bicarbonate is likewise separated from the liquor in any suitable manner.

In the saline solutions at Mono Lake and Searles Lake, California, gold in varying quantities is present in soluble form, probably in the form of gold chloride. The gold present in the saline solution subjected to my treatment, as above described, is reduced to an insoluble form and precipitated with the ferrous hydroxide from which it may be separated if present in any paying quantities by any suitable or preferred method.

Various changes may be made by those skilled in the art in'the steps of the process or in the construction and arrangement of parts of the apparatus without departing from the spirit of my invention as claimed.

I claim:

'1. An apparatus of the class described comprising a cell having liquid inlets and outlets, an iron anode, a non-corrodible cathode, and means for moving the iron anode.

2. An appartaus of the class described comprising a cell having liquid inlets and outlets, an iron anode in the center, and a pair of non-corrodible cathodes each equidistantly spaced from the anode.

3. An apparatus of the class described comprising a cell having liquid inlets and outlets, an iron anode in the center, a pair of non-corrodible cathodes each equidistantly spaced from the anode, and means for vibrating the anode.

4. An apparatus of the class described comprising a cell having liquid inlets and outlets, an iron anode, a rotatable shaft secured thereto, means for rotating said shaft, and a non-corrodible cathode.

5. An apparatus of the class described comprising a cell having liquid inlets and outlets, an anode in the center, said anode comprising a rotatable container, a shaft fastened thereto, means for rotating said shaft, scrap iron in sgid container in contact with said shaft, an a pair of non-corrodible cathodes each equidistantly spaced from the anode.

6. A process of treating a solution containing chlorides and carbonates of the alkaline metals, comprising subjecting said solution to electrolysis using an iron. anode, whereby iron hydroxide and bicarbonate of the alkaline metal are formed, and separating the iron hydroxide and the alkaline metal bicarbonate from the solution.

7. A process of treating a solution containing sodium chloride and sodium carbonate, comprising subjecting said solution to electrolysis using aniron anode, whereby 11011 hydroxide and sodium bicarbonate are tion.

8. A process of treating a solution con- 5 taining sodium chloride and sodium carbonate,

comprising subjecting said solution to electrolysis using an electric current of approximately 6 volts and. 15 amperes,

and

using an iron anode, whereby iron hyroxide and sodium bicarbonate are formed, and 10 separating said sodium bicarbonate and iron hydroxide from the solution.

In testimony whereof I have signed my name to this specification.

HERSCHEL o. PARKER.

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