US757817A - Process of electrolytically extracting copper and zinc from ores. - Google Patents

Description

No. 757,817. PATENTED APR. 19, 1904. s. LASZGZYNSKI. PROCESS OF ELECTROLYTIGALLY EXTRAGTING COPPER AND ZINC FROM ORES.

APPLIOATION FILED 00-1210, 1902.

no MODEL.

Witnesses Invent O7 Attaf'rvlys m: cams paws coy, momuma. wasmuumu, o. c

UNITED STATES Patented April 19, 1e04 PATENT OFFICE.

PROCESS OF ELECTROLYTlCALLY EXTRACTING COPPER AND ZINC FROM ORES.

' SPECIFICATION forming part of Letters Patent No. 757,817, dated, April 19, 1904.

Application filed October 10, 1902. Serial No. 126,649. (No specimens.)

To (LZZ whom, it may concern:

Be it known that I, STANISLAW LASZGZYNSKI, a subject of the Emperor of Austria-Hungary, residing at Kielce, Russia, have invented a new and Improved Process of Electrolytically Extracting Copper and Zinc from Ores, of

which the following is a specification.

IIllX or unite with the other in the absence of a diaphragm. The disadvantages of the diaphragm are well known. The difficulty in tightly fixing the diaphragm, of having to use two separate currents of liquid with corresponding systems of pipes for the anode and cathode bath, the giving away of the diaphragm during operation or at the filling of the cells, and other disadvantages have often proved so great as to practically carry out a process which theoretically promised great success.

The aim of the electrochemists is to carry on electrolysis without the use of a diaphragm, and a number of artifices are in use. Such an artifice, for instance, is the use of a mercury cathode in the decomposition of salt. In many cases+as, for instance, in producing chlorate, persulfate, and permanganateof potassium the one product may be obtained in an insoluble state which will not mix with the other product. Lastly, there are processes which are carried on without a diaphragm by making use of the different specific gravities of the products of reaction-as, for instance, in caustic soda and a solution of salt. This last means of course necessitates a horizontal arrangement of the electrodes.

The present invention has for its object a or envelop of porous fabric.

simple way of carrying out electrolysis without the use of a diaphragm.

By way of example I will describe the elec-- trolysis of a solution of sulfate of iron, FeSor.

111 there oxidized into trivalent ferri-ion (Fe) 3FeSOr The latter, however, before it is deposited as metalliciron has to be reduced at the cathode to ferro-ion. In this manner there is soon set up a state of equilibrium in which the same quantity of ferro-ions are reduced at the oathode as are produced at the anode. The chemical action of current, therefore, is m'l.

In the present process the detrimental side action at the anode is done away with by wrapping around the insoluble anode a cover The wrapping being permeable, there is before closing the circuit no diiference between the chemical composition of the anode and the cathode bath. As soon as the current is turned on, however, a layer of pure sulfuric acid will form around the anode, since there the S04 ions are discharged. Constantly new sulfuric acid is generated which can only drain off into the close-fitting envelop, displacing in this manner the solution of iron sulfate, so that in a short time the anode is surrounded by diluted sulfuric acid free from iron. At the same time a second process takes place similar to the one just described. Since the ferroions and the ferri-ions are cations, they travel at the closing of the current from the anode to the oathode. The envelop around the anode forms a layer of quiet liquid, no matter if the electrolyte is in circulation, so that the above-referred-to traveling of the cations can take place without being disturbed. The result of the two actions is that no ferro-ions can be oxidized, since none come in contact with the anode.

It is obvious that the described action will only take place when the envelop is wrapped tightly around thev anode. If a loosely-fitting envelop is used or diaphragms mounted on frames, currents of liquid from above to below will be set up, owing to the different specific gravities of the solutions. With the tight envelop such currents cannot be set up and the generated sulfuric acid can only filter into the next surrounding medium. Even at the upper end of the anode, at the level of the liquid, the generated sulfuric acid cannot sink at once to the bottom and be replaced by solution of iron sulfate, but is forced to pass first into the envelop just as at any other point of the anode. In this manner the immediate neighborhood of the anode is always kept free from iron.

The described action could not take place if iron were an anion, in which case it would travel to the anode. If a solution of potassium perchromate would be electrolyzed, the envelop could not prevent oxidation of the chromium oxid to chromic acid since chromium is anionic in such an electrolyte and accordingly travels to the anode across the perfectly permeable envelop in order to take thereup the generated oxygen. The envelop would also not prevent the electrolytic oxidation of the sulfuric acid to supersulfuric acid, likewise not the oxidation of the green manganite of potash to violet permanganate; butand this can only be explained by the traveling of the ions-the anodic envelop will prevent the oxidation of sulfate of manganese to permanganic acid, because in this instance the manganese is cationic and accordingly travels away from the anode and escapes theoxidizing action of the current. Lastly, the

laws of diffusion and of the traveling are tobe considered.

It is well known how slowly diffusion of metallic salts goes on and that, for instance, sulfate of copper disposed into strata with pure water takes some days to travel over a distance of one centimeter. This property is employed in the so-called gravity-battery, in which a concentrated solution of sulfate of copper is located on the bottom of a glass cylinder and above it, without diaphragm, a solution of sulfate of manganese. After a-certain time, be it even long, the sulfate of copper would come up to the top and there cause local actions on the zinc anode. For this reason cells of this kind are always kept closed under current. As long as these cells give current the copper travels, because it is cationic, to the cathode at the bottom of the vessel and away from the Zinc anode, and the solution is in the neighborhood of the said anode kept free from copper if the strength of current is great enough to counterbalance the diffusion.

. fuse.

In general already moderate strengths of current will be-suflicient for this purpose.

According to the experiments of Kohlrausch the traveling of the copper ion under the influence of the electric current is 1.2 centimeters within an hour. The quantity of copper traveling in a unit time through a unit distance is determined by the product of the electrochemical equivalent and the velocity of traveling. In the above-mentioned cells the electrolytic traveling works in opposite direction to the diffusion and makes it innocuous. There must be distinguished traveling of the ions under influence of current and the wellknown diffusion which takes place in every solution when there are layers of inequal concentration. In the above-mentioned case the two actions are opposite to each other and work in the opposite directions.

The present process is nothing but the practical application of the principle of the gravity-battery with vertical arrangement of the electrodes. There are no horizontal layers, but a porous partition imbued with a diluted solution of sulfuric acid, which partition is in a solution of sulfate of iron.

If we suppose 81 being the thickness of the partitionz'. 6., the distance the sulfate of iron must make going through the sulfuric acid n1the quantity of substance will take the time $1 for diffusing through a unit distance. At the way 82 2 s1,-the double time will be required for the diffusion of the same quantity of iron. In the same time as before (62 61) only half of the quantity 174 will dif- It is obvious that the quantities diffused are in inverse ratio to the ways:

The traveling of the ions takes place in opposite direction to the diffusion. The relation velocity of traveling velocity of diffusion equals constant, is indififerent according to the proportionality of the quantities in motion. The quantity of cations (l6) traveling away from the anode is in direct proportion to the density of current (d).

k1 gZ1 air In state of equilibrium, therefore, thethick- IZO ness of the envelop is in inverse proportion to the density of current. As well as the free ions also the not dissociated molecules are diffused, but the latter are inactive and not to be taken into consideration. I/Vith (Z equaling one hundred amperes per square millimeter and a concentration of the ferroions equaling half of the normal, 8 is about three millimeters. For manganese ions the same is valid between pretty large bounds. The oxygen generated at the anode is not prevented by the tight-fitting envelop from escaping.

The above-described phenomena may find a practical application in the electrolytic production of metals directly from the ore after extraction with sulfuric acid, especially in the production of copper and Zinc.

I desire to describe first the process of producing'copper, it being the more important, reference being had to the accompanying sheet of drawing, in which I have represented an apparatus adapted to be employed for the purpose set forth.

In the drawing, a is the electrolytic cell or tub, preferably made of wood and tightened,

with asphaltum or the like. Z) represents copper sheathings forming the cathodes, and 0 represents an anode which consists of refined lead and is provided with an envelop (Z of thick cotton stuif-for example, fustian.

All copper ores, without exception, contain iron, which when being treated with sulfuric acid dissolves, together with the copper. By the electrolysis the iron is oxidized at the anode to sulfate of peroxid of iron, which salt dissolves the copper deposited on the cathode equal to the action of diluted nitric acid.

q In this way the amount of deposited copper is not only reduced to one-half and even less, but also a brittle and inferior metal is obtained. Even if the ores contain but little iron the bath very soon will be enriched after a few extractions, and it will soon be impossible to electrolytically precipitate copper out of such a bath, inasmuch as the precipitation is equalized by the redissolution. To supply a fresh bath for every extraction cannot be done on an economical basis.

For the sulfurated copper ores the so called Siemenss process has evaded this difficulty by reducing after electrolysis the formed sulfate of peroxid of iron by heating it with fresh ore to proto-sulfate of iron. For malachitic and oxydic copper ores which cannot reduce the protosulfate of iron there is at present no electrolytical process in use, although it seems to be easy to treat the ore with sulfuric acid to precipitate electrolytically the copper and to use the generated sulfuric again over again as bath. Patents have been granted to processes for removing the iron from out of the copper-containing bath before electrolysis-as, for instance, by means of carbonate of calcium and by blowing in of air; but all these processes cannot be made use of for economical reasons.

The present invention now prevents oxidation of the iron salts and makes possible the di rect electrolysis of copper-baths containing iron, even if they contain twice as much iron as copper, with a useful effect differing but slightly from the theoretical, because the iron remaining at the state of the wholly inoffensive proto-sulfate of iron, (FeSO there is no corroding action of any kind. By means of the present invention a new branch of the metallurgy is opened to electrolysis.

In the process of obtaining zinc out of the ore by electrolysis the manganese ofi'ers difficulties. The iron can easily be removed out of the baths, as it is precipitated by the neutralization of the sulfuric acid through the ore; but all zinc ores contain more or less manganese, which is enriched after a few treatments, as it is not precipitated by electrolysis. In the electrolysis of a bath containing manganese with insoluble lead anodes the bath is stained adark red by the generating of supermanganesic acid, with the result that the zinc upon the cathodes is attacked and corroded In a test experiment with sulfate of zinc containing manganese it will be seen that in the presence of the envelop the solution will remain clear and stainless, while without the envelop deep red discoloration will take place. I By this means this difficulty. a, enriching with manganese salts, which, among others, caused the failure of the so-called Ashcroft processis easily and simply solved, themanganese sulfate not being oxidized at all.

What I claim, and desire to secure by Let ters Patent, is-

Process for electrolytically obtaining metals, especially copper and zinc, out of their ores by means of insoluble anodes, consisting in tightly wrapping the insoluble anode in a porous and perfectly permeable envelop of fabric or other suitable material, the thickness of which is in inverse proportion to the applied density of current. for the purpose of preventing anodic oxidation of the cations, substantially as set forth.

In witness whereof I have hereunto set my hand in presence of two witnesses.

STANISLAW LASZOZYNSKI. [n s]

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