US805969A - Separation of metals. - Google Patents

Description

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vNOAK VICTOR HYBINETTE, OE WESTEIELD, NEW JERSEY.

sEFnliFeATloN oF METALS.

Specification of Letters Patent.

Patented Nov. 28, 19U5.

T0 all whom it may concern:

Be it known that I, NOAK VICTOR HYBIs NETTE, a citizen of the United States of America, and a resident of Westfield, in the county of Union and State of New Jersey, have invented certain new and useful Im-v provements in the Separation of Metals, of which the following is a specification.

I have discovered a process 'for the economical separation of alloys intov their' constit'uents by electrolysis. It has been designed specially for the separation of nickel and copper from alloys of these metals, which are generally also associated with iron vbut it may be employed for the treatment of other alloys.

The fundamental principles on which the process is built are as follows:

First. 'If copper-nickel alloy is electrolyzed, the nickel will dissolve more rapidly from the anode and the result will be that the anode-slimes falling to the bottom of the tank lwill consist mainly of copper compounds. If at the same time sulfur is present in the anode, sulfid of copper is separated as anode-slime. This reaction is one of the means used in my process for separating copper from nickel. I find in practice that about one-half of the copper which I take into the process is recovered as such shines.

Second. There are at present in. use several well-known processes for removing large proportions of copperwfromcoppernickel mattes. matte is roasted and leached with sulfuric acid, lpractically only copper is removed une til the residue contains nickel and copper in the proportion of three. to one. I have therefore in my power to produce an anode containing 'three parts of nickel and one part copper, and by the selective action of the electric current I have only to .handle one part of copper to every six'parts of nickel through my electrolytic solution.

Third. By this combination of processes I therefore come down to such proportions between copper and nickel that it becomes commerciall y possible to eliminate the copper by allowing it to pass off as-an impurity through a solution ofnickel, which is regenerated or purified as soon as the copper has' accumulated in the solution to such an extent as to make the nickel deposit contain more copper than is allowed in the market.

Fourth. To be able to circulate a nickel solution-in the way now mentioned, it has l For instance, if a' copper 'rfrclel"""troducedmeans.b

`metal -on the cathode.

been necessary to invent a ready way to purify the same without in the least disturbing its plating qualities and return it in its original condition.

all of them have had to make up new solution from time to` time by an outside and independent process. NotA all nickel-plating solutions would besuitable for such a procphoric, boric, acetic, or lactic acid is added. 7o I -That nickel can be plated invsuch solution is not new but it has never been used for this e -Y purpose before. Fifth. Means by which such solution can be purified from copper will readily sug est l themselves to the trained metallurgist; ut for the best results commercially I want to make use of one particular way-namely, cementation-and in this connection I have Several electrolytic nickel 6o Vprocesses have been proposed in the past; but

discovered certain conditions under which the 8o low. With this system of circulation and puri- 8 5 cation the quality of the nickel produced to a certain eXtentwill only be a question of how fast the solution is circulated 5 but the -process would not be so economical hallnotin-WM which""a`pure nickel 9o could be produced at the same time, as the solution passing form the'plating-tanks contains a-considerable quantity of copper.

Sixth. I accomplish this end by separating anode from cathode in a novel way. It

is done by inserting between the two poles a lteringfdiaphragm directing the current of solution perpendicularly from the surface of the cathode to that of the anode. Such dia.-

phragms have been used before, but never Ioo for the purpose of separating metals from an alloy constituting the anode.` I believe Aalso that I am the rst one to use such diaphragm inI a case Where thek least decomposition of the solution would prevent the plating of the Furthermore, I do not know that anybody has succeeded in giving to such diaphragmv a mechanical construction whichwill allow of lits being used in an ordinary electrolytic plating tank where 1 Io the anode andv cathode are hung vertically.

AAfter now having given an outline of the different means which I employ for obtaining my results I will give a more detailed account of the different steps which constitute the process.

Referring to the drawings, Figure l is a vertical section of the apparatus which I use,

frame K and the two thicknesses of cotton cloth D, separated by the wooden frame K. C is the cathode-plate with the wooden rib E, which is shown in the drawings to extend over the bottom edge of the cathode; but it may for still better protection extend all around the plate.

B represents the anodes.

F is the inflow, which is regulated in such a way that the solution in the bag stands at the level II, which is about one inch above the level I.

The rib E prevents the cathode from warping and making contact with the bag.

In separating copper and nickel I preferably employ as electrolyte a dilute solution of sulfate of nickel with a small proportion of weak aeid-such as phosphoric acid, boric acid, lactic acid, or other organic acid well known to those conversant with the tradeand I particularly prefer a solution of nickel sulfate and weak acid so diluted that it will not crystalliZe at ordinary temperature. Other solutions-such as a very concentrated solution of sulfate or chlorid of nickel with or without inactive salts, such as sulfate or chlorid of aluminium or magnesium, used at comparatively high temperature and with high current density as means of making a coherent nicxel deposit-are not Well adapted to my process, .and I Atherefore intend to make a specific claim to the employment in this process of a solution of weak acid with the sulfate of nickel which will give good results at low temperature and with low eurrent density. My other claims, however, are not limited to the use of that particular solution.

The first step of my invention consists in placing in the electrolytic solution an anode composed of the alloy to be separated and a cathode-plate upon which the metal is to be deposited and separating the electrodes by.

a pervious diaphragm, such as lter-cloth or filter-paper. This is done, preferably, by

inclosing one of the electrodes, preferably the cathode, in a bag of such cloth or paper. In that it has a decided filtering capacity my diaphragm is of a dierent nature from those porous diaphragms ordinarily employed in electrolytie processes, which diaphragms al- 10W one reaction to take place on one side and a different reaction on the other side. My diaphragm is so porous that if it were alone relied upon to separate the anode side from the cathode side the solutions would mix and become homogeneous in a short time. Its action is therefore supplemented by keeping the solution in motion, causing it to flow from the cathode to the anode through the porous material, and thus preventing the metal which has been dissolved at the anode from coming into contact with the cathode. The diaphragm-bag is, in other words, only a convenient mechanical device for directing the circulation of the liquid in a direction from cathode to anode.

The anode may consist either of a pure alloy of copper and nickel, containing, say, equal parts of these metals or containing them in other proportions, or it may contain considerable proportions of sulfur, iron, carbon, silicon, oxygen, &c., its composition in this regard being determined by the conditions prevailing at the works where the 4 process is employed. When the copper contents are high, I prefer to remove part of it by some well-known process before making my anode. I have also found that an anode containing less than one per cent. of sulfur is preferable on account of the smaller percentage of scrap which remains after the solution of the anode. On the other hand, a higher percentage of sulfur will leave more cop per in the anode-shines'. I have also found that it is best to have not more than three or four per cent. of iron in the anode, as it is cheaper to remove iron by furnace treatment when it is in excess of that amount.

The cathodes preferably consist of copper plates, which should be greased or otherwise treated, so as to prevent the deposited nickel from adhering thereto, and each cathode made of heavy metal-say .10 to .15 inch thick-is held by a non-conducting, preferably wooden, frame. These thick metal plates when held in the frame will not warp and come into contact with the bags, whic 1 would interfere with the process. To make the bags more reliable, I prefer to employ two thicknesses of cloth at a distance from each other of about one-half inch, and this improvement I consider most important. The anodes described above are placed in the bath with the cloth-incased cathodes in vertical position. A solution of the metal desired to be plated on the cathode is caused to iiow into the bag and through the filter-cloth at right angles to the surfaces of the electrodes to the anode side of the tank.

By causing the solution to iiow in a regular stream into the cathode-bag it may be made to stand therein at a level of, say, about one inch above the level of the solution outside the bag, thus imparting to the entire body of the solution within the cathode-bag a uniform hydrostatic pressure of IOO IIO

i wardly through the pores of the entire bag in a directionperpendicular to the surfaces of the electrodes and at a uniform rate. The rate of flow is easily regulated by maintainin a desired difference of level between insi e and outside the bag-for example, by

yhaving an overflow at a proper level outside the bag and an inlet-pipe admittin thesulfate of-nickel solution in a -reguIated stream `inside the bag. I can thus maintain such a flow of the solution as will prevent any of the ions dissolved at the anodefrom penetrating the bag to the cathode side. Af-

ter the bag has been inuse some time the pores become filled up with'slimes of basic salts. This feature, far from being harmful, is a very desirable one. The electrical resistance of the diaphragm or bag is insignificantl and theplating process goes on apparently las. ifv no diaphragm were employed. There is, however, this important differencenamely, that an equivalent of nickel is deposited on the cathode within the bag and an ionof sulfuric acid is left free'. This ion decom oses the moleculenearest to it, and so on t rou hout the bath, so that the final exchange wi l cause an ion of sulfuric acid to be liberatedl at the anode and at the same moment an ion of nickel to be deposited at the cathode.l The ion of sulfuric acid at the anode immediately causes a-n ion of copper or nickel to be dissolved in the solution. As the exchange of ions goes on the newly-dissolved atoms of copper and nickel are traveling in a direction toward the cathode; but this movementis counteracted by the current through .the porous bag, and the dissolved ions cannot pass tol the cathode. Thus if I introduce into the cathode-bag.' a solution of nickel sulfate containing forty grams of nickel per liter the reaction will eave in the solution outside of the bag on the anode side of the tank, say, thirty-nine grams of nickel and one ram of copper per liter, the atomic weight of copper and nickel being approximately the same. A constant flow of the nickel `sulfate is suppliedl to the cathode-bag, and although plating is going on the solution standing in the bag does not become deprived of its nickel, and thereby acidulated, but it contains at all times the same forty grams of'nickel per liter. This process does therefore illustrate the theory for thewandering of the ions in a way that to my knowledge has never been done before.` The operation thus goes on continually, nickel being deposited at the cathode until a sufficiently thick platinghas been made,When the cathode-plates are removed and the vnickel stripped therefrom, and there is a correspondin simultaneous solution of the copper, nicke ,and iron at the anode until the anode is dissolved, when it is replaced by a, fresh anodeof impure alloy. The insoluble.

stantially from copper.

. age of carbon, silicon, or sulfur.

constituents of the anode-.such as platinum, palladium, gold, &c., together with considerable copper-are deposited as a slime on the bottom of the tank.y Copper, -and specially suliid of copper, is thus depsited as a slime, because the nickel of the anode being more electropositive is dissolved. at a more rapid rate.

If desired, the anodes may be set in the porous bags and the solution drawn off' from inside the bags. I prefer, however, to employ the arifangement above described.

n It is evident from what I have said above that the process can be worked under the claims without the porous diaphragm and that still by far the greater part of the copper can be separated, partly as slime and partly throu h the 'regeneration of the solution 5 but nic el produced in such a way will always be very impure and can either be sold as such forspecial purposes or else will have to be refined.

The second step of the operation is to reand complete cementation has only been obtained by-applying the nickel in the form of a fine powder, fresh portions of which are added to `the solution from time to time. Ordinary nickel inthe form of grains, shots, or sheets, such as are obtainable in the market, has been so slow in its cementing action that it is practically impossible' to use it when it is desired to free the solution sub- I have discovered that thev slowness of the cementing action which has attended such use of nickel is due to the fact that it has contained a small percent- If these im- IOO TIO

purities are removed, there is no trouble in cev j me'ntingxall thef-epper outof -a solution, especially when it is kept at a boiling temperature, and it is aremarkable fact that complete separation takes place even when the nickel, which is conveniently cast in slabs, becomes covered by a hard layer of cemented copper as much as an Vinch in thickness. I have also discoveredthat I can not only use pure-nickel slabs yin this process of cementation, but I .may employ efficiently slabs of copper and nickel alloy containing as much as thirty per cent. ofv copper, the alloy'being free from sulfur, silicon', and carbon,"A as above explained. This novelyusiefor such alloy is a very imp ortant'step process, inasmuch las the metal can befproduced cheaply-by roasting and smeltin'gof copper-nickel matte.

Therefore after dra/wing the solution from Lthe electrolytic tankI first heat it and then regenerate it with nickel by passing it into a vessel in which it is maintained at a boiling temperature and is brought into contact with suspended slabs of nickel and copper alloy containing,l say, thirty per cent. of copper. In this tank copper is very largely cemented out of the solution upon the slabs, its lace in the solution bein taken by an equivalent of nickel dissolved from the slabs, so that if on entering it contains thirty-nine grams nickel and one gram copper per liter it Will contain after cementation, say, 39.9 grams ofnickel and 0.1 gram of copper, together With some iron dissolved from the anodes. I then prefer to complete the cementationby transferring the solution into a second tank, Where it is also maintained at a boiling temperature in contact with pure nickel slabs, Which, being more efficient in cementing action than the copper-nickel alloy, will more rapidly remove every trace of copper, leaving the solution containing forty grams nickel per liter, as it originally did, minus the iron dissolved from the anodes, as Well as from the slabs of nickel and copper alloy. The nickel slabs should be free from the impurities above stated.

The next step of the process is to remove the iron. This I do, preferably, by passing the solution through an electrolytic tank containing insoluble anodes of platinum, lead, or carbon, by Which the iron compound is converted by oxidation from FeOSO3 to Fe2O33SO3. The solution is `then passed into a tank Where nickel carbonate is added to itin excess. This precipitates the iron as iron carbonate, and it is then removed from the solution by filtering.' The solution Which then contains the original forty grams per liter of nickel as sulfate is delivered into a tank or reservoir from which it is supplied to the porous cathode-bags, as explained above. The process is therefore a continuous one, the nickel electrolyte being supplied to the porous bags ina continuous stream, so as to maintain an outward current from the cathode, the equivalent of copper, nickel, and iron being dissolved in the liquid on the anode side. The liquid thus treated is regenerated by cementation on slabs or plates of nickel or nickel-copper free from carbon, silicon, and sulfur. The iron is then extracted from the solution, preferably byoxidation and precipitation, and the liquid thus regenerated and purified is again supplied to the electrolytic tank.

I have found that a current density at the cathode of ten amperes per square foot is suitable; but my invention is notlimited in this respect.

My invention may be employed for the separation of other metals. For example, in separating an alloy of copper, zinc, and lead I introduce a pure solution of zinc-salt into the cathode-bags and regenerate the solution soaee when drawn from the anode side of the bags by cementing it on zinc or zinc alloy. My invention lessens very greatly the cost of separating the constituents of alloys of this nature and it enables me to eiect great economy in the treatment of complex ores which hitherto have been separated by furnace treatment at very much greater expense. In some cases the expense has been so great as to be prohibitive, and as a consequence large bodies of such ores remain undeveloped.

The various steps of the process may be modified and the individual steps covered in the claims may be employed separately or.in other combinations.

The process of circulation by means of the porous bag, particularly in combination with cementation, is applicable to the separation of alloys in general. The particular cementation of copper on nickel and copper-nickel alloy is of great value in all processes of electrolytic refining of nickel and also in those cases Where electrolysis is not used.

. What I claim as my invention is- 1. The process of separating nickel from copper consisting in electrolyzing an anode containing lsubstantially an alloy of copper and nickel in a solution consisting of nickel sulfate and a Weak acid, regenerating the solution and returning the same.

2. The process of separating nickel from copper consisting in electrolyzing an anode containing substantially an alloy of cop )er and nicke in a solution consisting of niclkel sulfate and a Weak acid, removing the copper partly at least from such solution by cem entation on a metal containing nickel and returning the regenerated solution.

3. rIlhe process of separating nickel from copper consisting in electrolyzing an anode containing substantially an alloy of copper and nickeI in a solution consisting of nickel sulfate anda weak acid, removing the copper partly at least from such solution by cem,- entation on a metal containing cop )er-nickel alloy and returning the regenerate solution.

4. The process of separating nickel from, copper consisting in electrolyzing an anode containing substantially an alloy of cop )er and nicke in a solution consisting of niclkel sulfate and a Weak acid, circulating such solution in a direction from cathode to anode, regenerating the solution and returning the same to the cathode.

5. The process of separating metals consisting in electrolyzing an alloy, circulating the solution from cathode to anode, causing the solution surrounding the cathode to con tain only one of the metals constituting the anode, regenerating the solution partly at least by cementation on the metal produced in the electrolytic bath.

6. The process of separating metals consisting in electrolyzing an alloy, circulating the solution from cathode to anode, causing IOO IIO

the solution surrounding the cathode to contain only one of the metals constitutin the anode, regenerating the solution part y at, least by cementation on an alloy consisting mainly of the metal produced in the electrolytic bath.

7. The process of separating nickel from copper consisting in electrolyzing an alloy and removing the copper from the solution partly at least by cementation on slabs of metal consisting mainly of nickel and reiined at least to a point at Which carbon, silicon, and sulfur are practically eliminated. y

8. The process of separating nickel from copper consisting in electrolyzing an alloy and removing the copper from the solution c partly at least by cementation on slabs of metal consisting mainly of copper-nickel alloy refined at least to a point at Which carbon, silicon, and sulfur are practically elirnif nated.

9. The process of separating nickel from copper consisting in electrolyzing an alloy circulating the solution from cathode to ana ode, causing .the solution surrounding the cathode to contain nickel only, and removing f the copper from the solution partly at least by cementation on slabs or metal consisting mainly of nickel and refined at least to a point at Which carbon, silicon, .and sulfur are practically eliminated.-

10. The process of separating nickel from copper consisting in electrolyzing an alloy, circulating the solution from cathode to anode, causing the solution surrounding the cathode to contain nickel only, and removing the copper from the solution partly atleast by cementation on slabs rof copper-nickel alloy refined at least'to a point at Which car bon, silicon, and sulfur are practically eliminated.

11. The process of separating nickel from copper consisting in electrolyzing an alloy, circu ating the solution from cathode to anode through a porous diaphragm, causing the solution surrounding the cathode to contain nickel only, the solution on the other side of the diaphragm and surrounding the anode containing copper and nickel, preventing the nsisting in nelectrolyzing an. alloy, circulating the solution from cathode to anode through a porous dia hragm,l causing the solution surrounding t e cathode to contain only one of the metals constituting the alloy, and

the solution surrounding the anode containing all the metals dissolved from the anode, preventing the passage of the metals contained in theanode solution into the cathodecompartment by maintaining a pressure on :the cathode side, and circulating the solution through said diaphragm.

13. The process of se arating nickel from copper by electrolysis oi) trolyte of nickel sulfate and a Weak acid, circulating the solution Jfrom cathode to anode an alloy in an electhrough a porous diaphragm and maintainf ing a pressure on the cathode side and regenerating the solution partly at least by cementation on nickel.

14. The rocess of separating nickel from copper by e ectrolysis of an alloy in asolution of nickel sulfate and a Weak acid, circulating the solutionfrom cathode to anode through aporousdiaphragm, maintaining a pressure on the cathode side and regenerating the solution partly at least by cementation on copper-nickel alloy. l

Signed at New York, this 22d day of November, 1904.

NoAK vieron HYBINETTE.

Witnesses C. SEDGWICK, J. v M. HOWARD.

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