US415644A - Georg keener - Google Patents

Description

(No Model.) v

G. KERNER & J. MARX.

PROGESS 0P ELEOTROLYZING SALTS OP-THE ALKALIES. No., 415,644, Patented Nov. 19,1889.

N. PETERS, Pnoto-Lmw n her, Whhillgkm, D. c.

UNITED STATES 1 PATENT OFFICE.

GEORG KERNER, OF FRANKFORT-ON-THEMAIN, PRUSSIA, AND JULIUS MARX, OF ULM-ON-THE-DANUBE, VVIIRTEHBERG, GERMANY.

PROCESS OF ELECTROLYZING SALTS OF THE ALKALIES.

SPECIFICATION forming part of Letters Patent No. 115,644, dated November 19, 1889.

Application filed January 9, 1889. Eerial No. 295,904. (No model.) Patented in England May 2,1887, No. 6,417; in France .July 12,1887,No.184=,772; in Belgium July 19, 1887, No. 78,280, and in Italy June 19, 1888, XXII, 23,169, XLVI, 191.

To aZZ whom it may concern:

Be it known that we, GEORG KERNER, a subject of the King of Prussia, residing at Frankfort-on-th e-Main, Germany, and JULIUS MARX, a subj ect of the King of WViirtemberg, residing at Ulm-on-the-Danube, Germany, have invented new and useful Improvements in Electrolysis of Compounds Yielding Soluble Products by Combining Electrolysis with Chemical Precipitation, (for which We have obtained patents in England May 2, 1887, No. 6,417; in France July 12,1887,No. 181,772; in Belgium July 19, 1887, No. 78,280, and in Italy June 19, 1888, XXII, 23,169, XLVI,191,) of

which the following is a specification.

The process of electrolysis is employed with success in many manufactures, and numerous attempts have been made by Way of experiments and suggestions of patented and other methods or processes to render this force of nature available in the various branches of the manufacture of the salts of alkalies, alkaline, and other earths; but none of these methods'or processes have obtained any permanent success. This is to be attributed to the fact that the disuniting of the salts does not proceed as a simple and complete process, but, on the contrary, notwithstanding that the reverse has frequently been asserted, the practically possible extent of the decomposition is in fact merely partial, and keeps Within far too narrow limits. The removal of this evil or the discovery of some chemical or physical means by which it could be remedied or counteracted is consequently of the utmost importance. This problem is solved in a practical or commercial as Well as in a theoretical or scientific sense by means of the process constituting the object of the present invention, Which consists, essentially, in separating or removing the product resulting from the electrolysis by chemical means before or on reaching the limit at Which electrolytic action is practically arrested or ceases to produce a useful effect and continually subjecting the undecomposed portion of the salt remaining in the solution to further treatment in the same manner.

It is not essential to the success ofthe opapparatus suitable for electrolysis, and is applicable to the electrolysis of the Whole range of alkalies or alkaline and other earths such, for example, as sodium and potassium chloride, sulphate, phosphate or borate, chloride of magnesium, sulphate of magnesia, &c.,.also to the electrolysis of salts of lime, baryta, strontia, and alumina, and, in particular, of the mixed compounds of these salts.

In order to demonstrate the practical application of the principle of the invention, I Will now proceed more particularly to describe the same as applied to the manufacture of sodium bicarbonate and carbonate from sodium chloride.

The electrolytic vessel or chamber is charged with a solution (preferably nearly saturated) of common salt, and electric ourrent is caused to act thereon, whereby more or less of the chloride is decomposed into chlorine and caustic soda, according to the temperature and concentration of the solution and the tension of the current. This disuniting or decomposition of the chloride seldom affects more than about one-half of the salt originally employed, because the further action of the current, When once the caustic soda has become enriched to a certain extent, no longer affects the chloride, but almost exclusively affects the soda that has been formed. The limit of the production of soda by electrolysis is thus practically arrived at, but a solution is obtain ed containing along with the caustic soda only about one-half of the original quantity of chloride of sodium. A solution under these conditions is not suitable for further electrolysis, nor is it Well adapted for the direct extraction of caustic soda, thus proving the unsuitabilt-y of electrolysis for being employed alone or as the sole agent in operations intending the purposes of this description. By means of the invention being described this hitherto insurmountable difficulty is entirely removed through the products being Withdrawn from the action of the current by converting or reducing them In the case of common salt reduced by exhausting or dra'Wing,-or by fore-1 ing air through the apparatus. The dissolved chlorine, as well as the chlorate formed as a by-product can be readily removed by known means. The chlorate is enriched gradually and slowly in the solution, so that it can be precipitated with reconstitution of sodium chloride by. the addition of potassium chloride or other salts of potassium. Ohlorateof' potash is thus obtained as a by-product, along with the easily conveniently utilizable gaseous chlorine. This chlorine may of course constitute the main product or object of the treatment, being, 'as already stated, capable of being utilized at will for the manufacture of chemical products or other industrial purposese. 9., for bleaching-when it may beemployed in the form of gas or as! a solution, either alone or mixed with other substances or alkaline matter-suchff'or example, as the solutions at the cathode.

When the substance liberated at the anodei is some other material than chlorinesucl 1 as sulphuric acid, for exampleit is evident that a different precipitant must be employed} For example, chalk carbonate of lime may be substituted for the chloride of potash if it; be desired to render the sulphuric acid harm-, less. The oxygen can be readily separated from the carbonic acid and collected, the oxygen being employed for any suitable pur-;, pose and the carbonic-acid being utilized for precipitating the alkali.

in like manner suitable other salts of lime-such, for example, as phosphate of limecan be employed in place of chalk, to be disaggregated or refined in this way; or the resulting sulphuric acid.

set free from alkaline sulphates in this combined process is employed and applied to for'm muriatic or hydrochloric acid by the;

addition of chlorides-such, for example,-as chloride of calcium. be conducted in separate vessels, chambers, compartments, or the'like,'if desired. 7

At the cathode where the caustic soda is produced the difficulties of the electrolysis are greater, as already explained; but according to this invention they are effectually removednamely, the product formed by electrolysis being obtained on the one hand, and

These operations can on the other hand the residual chloride solution is rendered fit and available for and employed in further electrolysis.

The electrol ytical product is obtained by converting it: into a comparatively insoluble compound,

such as bicarbonate of soda, whichseparates by precipitationand this operation can evidently be performed during the progress of the'electrolysis or otherwise, and either inthedouble salt by the co-operation of magnesia employed partly asa vehicle, with which object the magnesia is suspended or kept swimming in the solution under treatment. By thusemploying magnesia as a vehicle'for the carbonic acid the application of the pressure otherwise required to introduce the carbonic acid may be reduced, and an-eitectu al precipitation is obtained in the preparation'of carbonates'of potash also. In this carbonating process the magnesia may be added in the form of a hydrate or a carbonate, or the -;process maybe so conducted that an alkaline salt containing magnesia such as naturalor arti ficial cornalliteis originally subjected to the electrolysis and provides the magnesia required for thes'aid carbonating. After the decomposition of the double salt resulting from the combination of the alkaline and magnesic carbonate magnesia is recovered in addition to the carbonate of the alkali. Zinc and certain other bases may be em-ployed in place of the magnesia, -'and,-together with the al-kalies and carbonic-ac id form double salts soluble with difficulty. The alkalinecarbonate resulting from the decompositionof these double salts is obtained by filtration, suction, centritugation, or othersuitable treatment.

The bicarbonate maybe decomposed inthe usual way; but in this-casea light product unsuitable for 'many'applications is obtained a defect which can be effectually remedied by mixing the precipitated bicarbonate as quickly as posssible with caustic alkali or with the uncarbonated lye dischargedfrom the electrolyzing-chamber on the cathode side and separating or centrifugating it immediately thereafter. The bicarbonate is thus transformed into the carbonate, which cannot dissolve, owing to the rapidity of the liquid'being drawn off, and yields acompa'ct or dense soda after'calcination. The runping-off solution is simply subjected to further treatment in the manner described.

. The operation might be similarly conducted in treating the double carbonates of magnesium and alkali, these products also being decomposed by boiling or evaporating at an elevated temperature or by passing superheated steam through, when the solution of the carbonate may be concentrated at will, if desired, so as to admit of the direct production-of crystalline'soda. After the canstic soda obtained from thechloride by electrolysis has been removed from'its'solu tion by any of "the methods hereinbefore describedthe remaining liquor is returned to the electrolyzing apparatus for further treatment, preferably in practice being previously enriched by the addition of a suitable quantity with an electrical generator.

taining the greatest quantity of caustic soda may be opposed to the solution containing the smallest quantity of chlorine, so as to lessen the tendency to recombine, the disadvantages connected therewith being thereby considerably diminished, while at the same time the electrolytic action is promoted.

It is evident that the electrolytic process hereinbefore described is equally applicable to the electrolysis of other saltssuch, for

example, as sulphates from which sulphuric acid is obtained. The base may also be different, as liereinbefore described. The application of the process to the electrolysis of mixed salts of the alkalies or alkaline and other earths is of especial importance, it being known that the current decomposes these salts in a definite order, so that the several bases and acids can be obtained separately after having made the necessary adaptations resting in the professional scope. The anode .products are well known, but their production on a practical and commercial scale by electrolysis is not possible except by means of the combined electrolytic and chemical process hereinbefore described. Thereby the electrolysis of the alkaline salts and the like for the first time is madeto be performed under favorable conditions, and thus the anode products-such as chlorineare forming an integral part of the process.

The operations may be conducted with solutions at ordinary, at lower, or at elevated temperatures, and the liquids may or may not be heated or concentrated before or after the precipitation. I

The accompanying drawings illustrate apparatus which may be employed in carrying out the invention; but, as mentioned, the new process does not depend upon them, as any electrolytical apparatus may serve or be adapted for that purpose. These drawings are only intended to facilitate understanding.

Figures 1, 2, and 3 represent, respectively, a longitudinal section, a transverse section, and a plan of an apparatus in which the precipitation is caused to take place in electrolyzingvessel. A is the electrolytic vessel or chamber. B is the cathode, and O the anode. The cathode and anode are connected by wires E D is the diaphragm. F is a perforated pipe through which carbonic acid is conducted into the liquid at the cathode side for the purpose of precipitating the caustic alkali in the form fect electrolysis and precipitation in the same vessel. to is a pipe for introducing the electrolyte. b is the outlet for the electrolyte in the cathode-compartment. c and d are similar pipes in the anode-compartment. The liquid to be electrolyzed flows in on the cathode side at A and flows out at B. On the anode side the liquid flows in the opposite direction, entering at c and escaping at (Z.

Fig. 4 illustrates in plan an arrangement of apparatus in Which the product of the electrolysis is precipitated outside of the electrolytic chamber and the liquids are kept in continuous circulation. A is the electrolytic chamber; B, the precipitating-chamber for the cathode products. 0 is a chamber in which the liquid is enriched before re-entering the chamber A. The liquid is caused to return to the chamber A by the action of a pump. P, D, and F are a pump, a precipitating-chamber, and an enriching-cistern for She liquid on the cathode side. The direction in which the liquids are caused to circulate is indicated by the arrows.

Having now described the nature of our invention and the manner in which the same has to be carried out in practice, we wish it to be understood that We do not claim, broadly, the decomposition of soluble compounds by electrolysis nor do we claim, in general, a process for precipitating certain substances out of their solutions. These processes are well known in the art, but

What we claim as our invention is 1. The process of obtaining certain useful products from the compounds of the alkalies by chemical action concurrent with electric action, consisting in first electrolyzing a solution of such compound, then at the same time subjecting the soluble electrolytic products to chemical precipitation when or before the electrolytic action upon the salt to be decomposed practically ceases, as and for the purpose set forth.

2. The process of obtaining certain useful products from the compounds of the alkalies by chemical action concurrent with electric action, consisting in first electrolyzing a solution of such compound, then at the same time subjecting the soluble electrolytic product to chemical precipitation when or before the electrolytic action upon the salt to be decomposed practically ceases, in combination with heating, cooling, and partial evaporation, as and for the purpose set forth.

3. The process of obtaining certain useful products from the compounds of the alkalies, consisting in first electrolyzing such compound and then subjecting the soluble electrolytic product to chemical precipitation by the simultaneous action of magnesia and carbonic acid to precipitate a double carbonate of alkali and magnesia, as and for the purpose set forth.

4:. The process of obtaining certain useful ITO products'fi-omthe-coinp0ui1ds of the alkaliesb'ychei'nical "action concurrent 'With'el'ectfic action, consisting in first electrolyzing ascl-utionof 's'u'c'h compound, then at the same tiihe subjecting the soluble electrolytic 'products to chemical precipitation when-0r before the-electrolytic action upon the salt'to-he decomposed practically ceases by action 'of' carbonic acid to precipitate bicarbonate 0t sodiuih, as and forthe fpur'pose set forth.

5. The "processof obtaining certain useful productsfi'oin the compounds of'sodium, con- Sistingi'nfirst electrolyzing'asolution of such compound and then subjecting the soluble electrolytic products to chemical precipitzv tion by the action of bicarbonate of'sodium,

to be executed in such a manner thatthe bicarbonate be quickly mixed 'with the "electrolyzed solution containing'causfticsoda andimniedia tely'after mixing removed, as and for the pur ose set forth.

In testimony whereof 'W'e have'sigiied our names to this specification in the presence of two subscribing Witnesses.

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