US1260661A - Method of recovering metals from alloys. - Google Patents

Description

UNITED STATES PATENT OFFTQE.

JULIUS H. GILLIS, OF TORONTO, ONTARIO CANADA, ASSIGNOR TO BRITISH AMERICA NICKEL CORPORATION LIMITED, OF TORONTO, ONTARIO, CANADA, A CORPORATION Patented Mar. 26, 1918.

OF CANADA.

METHOD OF RECOVERING METALS FROM ALLOYS.

1,260,661. Specification of Letters Patent.

No Drawing.

To all whom it may concern:

Be it known that I, JULIUS HOWELLS GIL- LIS, a citizen of the United States, residing at Toronto, Province of Ontario, Canada, have invented certain new and useful Improvements in the Methods of Recovering Metals from Alloys, of which the following is a specification.

This invention is an electrolytic method whereby a metal may be recovered in a state of substantial or commercial purity from its alloys. The invention will be described by reference to a specific illustrative example thereof, according to which nickel is deposited at the cathode, a nickel-copper anode being employed: but the novel principle thereby illustrated is applicable to the electrolytic recovery of other metals from their alloys.

Nickel-copper alloys wherein nickel predominates are readily obtainable by smelting the appropriate ores. As an illustration of this invention, I cast into any convenient anode form an alloy containing for example about two parts of nickel by weight for each part of copper. This anode is suspended in a suitable electrolyte, for example a weak solution of nickel sulfate, together with a cathode of sheet nickel, iron or other appropriate material. If now the electric current be caused to flow from the anode to the cathode through the electrolyte, as under the usual conditions for electro-depositing metals, it will be observed that for a short period of time the cathode deposit will consist of pure nickel. During this same period both nickel and copper will pass into solution at the anode, the nickel in predominating proportion. This is due in part to the fact that nickel predominates in the composition of the anode, and in part to what ma for convenience be termed the selective ef feet of the current, under the influence of which nickel tends to dissolve more rapidly than copper. If the electrolysis be continued under these conditions, copper will begin to separate at the cathode.

If, however, the polarity of the electrodes be reversed, or the current be caused to flow to the alloy electrode as cathode, the socalled selective effect of the current is again displayed, and the copper is re-deposited at the alloy electrode, while at the same time a Application filed September 4, 1917. Serial No. 189,601.

certain quantity of the deposited nickel is re-dissolved from the electrode which originally functioned as the cathode. The amount of nickel thus dissolved is nearly equivalent to the quantity of copper re-deposited, but represents only a fraction of the total nickel which was electrodeposited before the reversal of the polarity. There is therefore a certain net gain of nickel deposited upon the cathodeyand inasmuch as the copper ions have been driven from solution, the electrolyte is restored to its original purity. The copper is re-deposited in loose or non-adherent form upon the alloy elecmode, this slime or mud falling to the bottom of the cell and leaving the anode in good condition for further dissolution when the original polarity is restored. Therefore I am enabled, by reversing the current at proper intervals and for proper periods, to recover the nickel in the form of a reguline cathode deposit, while obtaining the copper as an anode slime. Although as above stated the operation may be so conducted as to afford a substantially pure cathode deposit of nickel, an absolute separation as between nickel and copper is not essential to the practice of my invention. I have found it desirable in practice to reverse the current at very short intervals,

so that time is not afforded the copper ions to wander too far from the alloy electrode. For example, ten reversals of the current per minute, each reversal having a duration of approximately two seconds, has been found in practice to give satisfactory results with an alloy anode of the characterabove mentioned; although it will be understood that my invention is not limited to these specific conditions.

The duration of the current flow to the alloy electrode functioning as cathode, or in other words, the duration of the reversed flow, is so regulated as to suffice only for the re-deposition of the copper which has been dissolved: but it will be clear that this regulation may be accomplished either by using the reversed-current (flowing to the alloy electrode as cathode) for a reduced period as compared with the direct flow; or, alternatively, by maintaining the same or even longer time intervals during the reversal, and correspondingly reducing the current flow (amperage), as for example by reversing the current through a rheostat or other suitable resistance, or the like.

I have also found that the copper-bearing anode slimes contain certain impurities, such as iron, the separation of which from nickel in electrolytic processes has heretofore presented serious difliculties.

I also find it to be an advantage to separate the electrodes by a porous diaphragm, which prevents the impure slimes from crossing over and being deposited on the cathode without electrolytic action, but I do not intend that my invention shall be limited in this respect.

If instead of reversing the current the latter be merely interrupted, the interruptions being sufficiently prolonged, a somewhat similar etfect as to precipitation of copper is secured, owing to local currents set up within the cell. This actlon, however, is relatively very slow, and it is therefore preferred to impress current from an outside source upon the cell during the period of reversed flow. Nevertheless, I regard it as within my invention to interrupt the current for the time and at the intervals necessary to accomplish the results herein above described.

I claim 1. The method of recovering metals from alloys thereof, which consists in passing an electric current from an alloy electrode to a suitable cathode through an electrolye containing a salt of a metal to be deposited; and reversing the polarity of the electrodes at such intervals and for such periods as to avoid substantial deposition upon the cathode of any undesired components of the alloy anode.

2. The method of recovering nickel from nickel-copper alloys, which consists in passing an electric current from a nickel-copper anode to a suitable cathode through an electrolyte containing a s It of nickel; and reversing the polarity ofthe electrodes at such intervals and for suchperiods as to avoid substantial deposition of copper upon the cathode.

In testimony whereof, I aflix my signature.

JULIUS H. GILLIS.