US415576A

US415576A - Werner siemens

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Publication number: US415576A
Authority: US
Publication date: 1889-11-19
Anticipated expiration: 1906-11-19

Description

' (No Model.)

W. SIEMENS. PROCESS OF ELEOTRO DEPOSITION 0P METALS.

No. 415,576. Patented Nov. 19,1889.

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UNITED STATES PATENT OFFICE.

IVERNER SIEMENS, OF BERLIN, GERMANY, ASSIGNOR TO SIEMENS otHALSKE,

OF SAME PLACE.

PROCESS OF ELECTRO-DEPOSITION OF METALS.

SPECIFICATION forming part of Letters Patent No. 415,576, dated November 19, 1889.

Application filed April 11, 1887. Serial No. 234,446. (No specimens.) Patented in Italy October 30, 1886, No. 20,638, and in Spain November 29,1886, No. 10,139.

To aZZ whom, it may concern:

Be it known that I, WERNER SIEMENS, of Berlin, a subject of the King of Prussia, residing at Berlin, in the German Empire;

' have invented certain new and useful Improvements in the Process for the Electro- Deposition of Metals, (for which I have obtained a patent in Italy, No. 20,638, bearing date October 30,1886, and in Spain, No. 10,139, dated November 29,1886,) of which the following is a specification.

Hitherto it has been usual in the electrolytical extraction of metals to use as anodes plates of the metal to be obtained, which plates were prepared by smelting ores containing the metal, and thus they contained many of the impurities of the ores from which they were cast, notably iron. When these plates were submitted to the action of the electric current and electrolytic solution, the metal to be extracted and the iron were both dissolved out of them, and the copper thus obtained deposited in a metallic state at the cathode, whereby the electrolytic solution had to be replaced by a fresh one and the anodeplates dissolved; but, in addition to these, the anode-plates often disintegrated before their complete dissolution. In these cases it will be seen that there are three principal causes of expense and troubleviz., the preparation of a new electrolytic solution from the ore, the preparation of. new anodeplates, also from the ore, which was often difficult and uncertain, and the disintegration of the plates when formed.

My invention has for its object to obviate these difficulties; and it consists in the following process: subjecting a solution of a salt of the metal which it is desired to obtain and of a ferrous salt to the action of a cathode-plate, whereby the desired metal will be deposited and the element or elements in chemical com- .bination therewith will be liberated; subjecting the outflowing liquid to the action of an anode-plate of insoluble material-such as carbon, platinum, or lead, or of a plate covered with platinumthe said cathode-plate being separate from the anod e-plate by a nonmetallic diaphragm which is impervious to the solution, but which allows the electric current to pass, whereby the free elements liberated by the cathode-plate will be caused to enter into chemicalcombination with the ferrous salt, converting the latter into a fer ric salt, and, finally, lixivaiting ore containing the metal to be extracted with the solution of the ferric salt obtained from the anode-plate, whereby the metal will be dissolved and the ferric salt reconverted to a ferrous one, and a solution obtained with the same chemical constituents as that first passed under the influence of the cathode-plate, or, instead of subjecting the electrolytical solution to the action of a single pair of plates only, several anode and cathode plates may be used, and the solution subjected successively to each, as will be hereinafter more fully described and claimed.

Referring to the accompanying drawings, which represent apparatus suitable for use in carrying out my invention, and in which corresponding parts are designated by similar letters, Figure l is a vertical section of a single cell, and Fig. 2 is a vertical section of a series of cells in which the liquid passes from the compartments of the one to the other.

B, Fig. 1, represents a cell in which a nonmetallic diaphragm D is placed, having near the upper edge of the cell a mouth R, through which the liquid in the outeror cathode compartment B may flow into the inner or anode compartment B when it has reached its level. The diaphragm D, which is constructed of a substance impervious to the electrolytical liquid, but through which the electric current may pass, is suspended in the cell B by means of beams 13 preferably of wood. The funnel B has its downtake B extending to near the bottom of compartment 18. The plate K is suspended in the same compartment from the beam 13, similar to beams B the plate being connected with the negative pole of a source of electricity, and thus form ing the cathode-plate. In the compartment B is suspended the plate A, of carbon, platinum, lead, or other insoluble material, or a plate covered with platinum, the plate being connected with the positive pole of the source of electricity and suspended from the beam B thus forming the anode-plate. The arm 0 of the siphon M, which rises over the edge of the cell, extends to the bottom of compartment B and has a neck C on the outside of the cell, the said neck extending below the level of the mouth R of the diaphragm D, while the level of the outlet C of the siphon is on aslevel therewith, whereby, the siphon, when once" filled with the contents of compartment B is prevented from drawing off its contents below the level of the mouth R, and the upper part C of the siphon prevented from becoming filled with air, which would prevent its action.

When the electrolytioal solution is to be subjected to the action of several cells successively, the apparatus represented in Fig. 2 is used. In this construction the cells E E E &c., are placed in series, the first cell E being at a greater height than the succeeding one. In each of these cells is a non-metallic diaphragm D, inclosing the cathodecompartment K while the anode-compartment A surrounds the said diaphragm. The anode-compartment contains the anode-plate A, while the cathode-compartment contains the cathode-plate K, as has already been described in relation to the construction of a cell adapted for separate use. Funnels A and K are provided for the anode and cathode compartments, respectively, of the first or upper cell E, the downtake a of the funnel A extending only a small distance below the level of the top of the liquid in the anodecell, while the downtake extends to near thebottom of the cathode-compartment. A siphon K rises from near the top of the liquid in the cathode-compartment K of each cell, and, after forming a neck k, ends in the cathode-compartment of the next succeeding cell. The height y of the neck 7i) is by preference equal to the difference of height 2 between the successive cells. A siphon A similar to K, rises from near the bottom of the anode-compartment A of each of the cells, and, after forming a neck a, ends in the anode-compartment of the succeeding cell. By means of the necks a and 7c the upper bends a and 7c of the siphons are kept constantly filled, and the liquids in each of the cells is prevented from falling to a lower level than that of the upwardly-opening ends a and 70 of the siphons A and K, which terminate in the succeeding cell.

In the use of the apparatus illustrated in Fig. 1 a liquid containing the metal to be extracted and a ferrous salt is slowly but continuously fed through the funnel l3 and downtake B into the bottom of the cathode-compartment B, where, yielding up the desired metal to the cathode-plate, it becomes lighter, and, rising along the plate, deposits still more of its metallic contents thereon, and finally passes over mouth B into the anode-chamber B where the liquid is subjected to the action of the anodewill be hereinafter described, and the con verted liquid, which will have become heavier, will sink to the bottom of the compartment and be drawn off by the siphon M.

In the apparatus shown in Fig. 2 the operation is as follows: The electrolytical solution is fed down the funnel K and downtake k to the bottom of the oathode=compart1nent of the upper cell E, Whereit will, as in the previous case, become lighter by deposition of the metal which it is desired to extract, and, flowing upward, will enter the siphon K and be drawn by the action thereof into the cathodecompartment of the succeeding cell, and so continue to pass through the cathode-compartments of as many cells as may be employed, leaving in each a part of the desired metal. As the ends of the effiux and influx siphons K of the cathode-compartments K of each of the cells E E 850., are near its top, the liquid contained in such compartments should be agitated in any suitable manner in order to secure a circulation at the bottom thereof. After the liquid has passed through all the cathode-compartments and is freed from the metal to be extracted it is fed into the upper part of the anode-compartment of the first cell E through the funnel A and downtake a Here it is acted upon by the anode-plates and becomes heavier, sinking and flowing through the siphon A to the top of the anode-compartment of the next cell, where, under the further action of the anode-plates contained therein, it becomes still heavier, and, again sinking, flows to the anode-compartment of the next cell, until it has passed through the anode-compartments of all the cells.

My invention may be used in several cases,

as will be hereinafter shown. In the first of these it may be desired to extract copper by means of a sulphate solution, in which case the liquid subjected to electrolysis consists of a solution of ferrous sulphate (FeSOQ and cupric sulphate (CuSO and some free sulphuric acid, (H SO which is added to improve its conductivity. The liquid which is used at the beginning of the operation is formed in any suitable manner, as by dissolving copper and iron in sulphuric acid. This liquid is then led into the cathode-compartment of the single cell B or in the cathodecompartment of the first cell E of the series of cells illustrated in Fig. 2. Here the cupric sulphate is decomposed, the copperbeing deposited in a metallic state, while the sulphur and oxygen are still contained in the liquid and carried thereby. The solution, becoming lighter by the deposition of a portion of its metallic contents, rises in the cathode-coinpartment. In case the series of cells are used, the solution, having passed through the oathode-compartment of one cell, passes through the corresponding compartments of the other cells until it has passed through the full series and is entirely freed of its copper. The

plate. The chemical action in this chamber liquid after passing through the cathode-compartments is fed into the anode-compart' verting the sulphides of copper (CuS and CuS and oxide of copper (CuO) into sulphate of copper. The ore to be treated may consist of copper pyrites, which is first pulverized and roasted at amoderate heat (best in a Gerstenhafers furnace) to such a degree that the iron contained originally in the pyrites is almost entirely oxidized, in which state it is not affected by the ferric sulphate, while the copper is contained in the roasted ore partly as sulphate of copper, but for the most part as subsulphuret of copper, (Ou S.) The ore so prepared is then submitted in suitable lixiviating compartments or vessels to the action of the liquid flowing from the anode-compartments. The ferric sulphate contained in the liquid converts the sulphide of copper and oxide of copper of the prepared ore into sulphate of copper, which will be taken up into solution, while the insoluble oxide of iron remains, and the ferric sulphate in acting upon the ore will be reconverted into ferrous sulphate.

The chemical action occurring in the electrolysis and extraction may be seen from the following equation:

First, occurrence during electrolysis Second, occurrences during extraction- By comparing formula 1 and 2 it will be perceived that if the ore contains all the cop per in the form of subsulphide of copper the el ectrolytical liquid, after passing through the extractingvessels, will contain precisely the same quantity of sulphate of copper, ferrous sulphate, and free sulphuric acid as before the electrolysis, being regenerated, and is therefore adapted to be again led to the galvanic cells to undergo the same treatment, causing this to be a continuous process, in which the same liquid may be used until it has, by absorbing foreign metals from the ore, become too impure for further use in this manner. The solution when fed into the cathode-compartment may be of any desired strength, and I by preference employ an electric current amounting to twenty-five amperes per square meter of the surface of the cathodeplate.

An analogous method for the electrolytical separation of copper is the process of chlorinization. The electrolytical liquid then consists of cuprio chloride (01101,) and ferrous chloride, (FeCl from which in the galvanic cells copper and ferric chloride (Fe Ol are obtained according to the following equation: CuCh-l-QFOh:Qu-l-Fefih.

The ferric chloride thus formed possesses the power of converting sulphide of copper not decomposed by roasting into cupric chloride, (OuC1 and also of converting, with the aid of a solutionpf chloride of sodium, (NaOl,) cuprous' chloride (011 01 into cupric chloride. In either case ferric chloride is reduced again into ferrous chloride. Thus, also, in this process the solution is regenerated so that it becomes again suitable for electrolysis, and no polarization takes place. In the use of anodes consisting of matte of copper a difference of potential of about 1.5 volts is consumed and about one-third of the current employed in doing other work than that of reduction, and is thus lost, while by the process above described a tension of 0.7 volts, with double the density of the current, is sufficient, all of which is employed in the reduction of the solution. The same process can be further used for an electrolytical extraction of zinc from sulphurized zinc ores "with the aid of a solution of sulphate of zinc (ZnSOQ and ferrous sulphate.

In the electrolytical cells zinc and ferric sulphate are formed according to the following equation:

ZnSO,|2FeSO,- :Zn+Fe (SO,) The ferric sulphate thus formed possesses the property to dissolve zinc out -of the slightly-roasted zinc blendes, (ZnS,) and sulphate of zinc and ferrous sulphate are formed according to the following equation:

ZnS-l-Fe (SO,) :ZnSO,+2FeSO,l-S.

A comparison of this and the preceding equation will show that, after the slightly-roasted zinc blendes have been acted upon by the liquid, the amount of iron and zinc therein has become as great as before electrolysis.

An analogous process can be used for the extraction of zinc by means of a solution of chloride of zinc ZnOl and ferrous chloride. In this instance in the electrolytical cells zinc and ferric chloride are formed, which latter can again dissolve zinc out of zinc blendes by being reduced to ferrous chloride. Of course in the zinc processes the difference of potential in the electrical current, must be nearly twice as great as in r the cop.- per processes above described to overcome the counter-current created by the tension between the zinc and carbon.

The principle utilized in the process above described is that oxidizable solutions conducting electricity are oxidized at an anode which consists of carbon (or even platinum, gold, or lead, &c.)- under certain conditions by the galvanic current to a higher degree than they were before without effecting polarization. This principle can also be utilized for other chemical operations by arranging the decomposition apparatus in such a way that in. the cells surrounding the ITO 7 in the electrical circuit.

In order to cite some examples of chemical operations effected by this process, it may be stated that by it, at a very low expense,

ferric salts can be obtained at the anode plate from ferrous salts, ferric chlorides from ferrous chlorides, ferric cyanides from ferrous cyanides, (for instance, red from yellow prussiate of potash,) while in the cathodecompartments metals (for instance, copper, iron, zinc) can be precipitated from the corresponding salts solutions and hydrates of potassium or sodium formed, &c.

Having thus described my invention, what I desire to secure by Letters Patent is v 1. The process which consists in lixiviating ore with a solution containing a ferric salt,

subjecting the resulting ferrous solution at the cathode of an electrolytic'cell to the action of a current of electricity, whereby the metal in solution is deposited, then subjecting the remaining liquid to the oxidizing action at the anode, whereby the ferrous is reconverted into a ferric solution, which solution is again used to lixiviate ore.

2. The process which consists in lixiviating ore in separate vessels with a solution con= taining a ferric salt, subjecting the resulting ferrous solution at the cathode of an electrolytic cell to the action of a current of electricity, whereby the metal in solution is-deposited, then subjecting the remaining liquid to the oxidizing action at the anode, whereby the ferrous is reconverted into a ferric solution, which solution is again used to lixiviate ore.

The process which consists in lixiviating ore in separate vessels with a solution containing a ferric salt, passing the resulting ferrous solution successively through a series of compartments containing cathode-plates, and in which cells the solution is subjected to the action of an electrical current by which the metal in solution is deposited, then passing the remaining liquid successively through a second series of compartments containing anode-plates of insoluble material and separated from the first-mentioned compartments by non-metallic diaphragms, whereby the ferrous solution is oxidized and reconverted into a ferric solution, which solution is again used to lixiviate ores.

4. The process which consistsin lixiviating ore with a solution containing ferric sulphate, subjecting the resulting ferrous sulphate at the cathode of an electrolytic cellto the action' of a current of electricity, whereby the metal in solution is deposited, then subjecting the remaining liquid to the oxidizing ac tion atthe anode, whereby the ferrous sulphate is reconverted into ferric sulphate, which solution is again used to lixiviate ore.

5. The process which consists in lixiviating ore in separate vessels with a solution containing ferric sulphate, subjecting the resulting ferrous sulphate at the cathode of an electrolytic cell to the action of a current of electricity, whereby the-metal in solution is deposited, then subj ecting the remaining liquid to the oxidizing'action at the anode, whereby the ferrous sulphate is reconverted into ferric sulphate, which solution is again used to lixiviate ore.

6. The process which consists in lixiviating ore in separate vessels with a solution containing ferric sulphate, subjecting the resulting ferrous sulphate at the cathode of an electrolytic cell to the action of a current of electricity, whereby themetal in solution is deposited, then subjecting the remaining liquid to the oxidizing action at the anode, thesaid anode being separated from the cathode by a diaphragm, whereby the ferrous sulphate is reconverted into ferric sulphate, which solution is again used to lixiviate ore.

7. The process which consists in lixiviating ore in separate vessels with a solution containing ferric sulphate, passing the resulting ferrous sulphate successively through a series of compartments containing cathodeplates, and in which cells the solution is sub- .jected to the action of an electrical current by which the metal in solution is deposited, then passing the remaining liquid successively through a second series of compart ments containing anode-plates of insoluble material and separated from the first-mentioned compartments by non-metallic diaphragms, whereby the ferrous sulphate is oxidized and reconverted in ferric sulphate, which solution is again used to lixiviate ores.

WERNER SIEMENS. Witnesses:

F. VON VERSEN, B. R01.