US1441567A - Electrode - Google Patents

Description

Patent an. 9, 12:5.

COLIN G. FINK, 0E YONKERS, NEW YORK, -ASSIGNOR T0 CHILE EXPLORATION COM- PANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

ELEcrEonE.

No Drawing.

To all 'whom it may concemn 1 Be it known that I, COLIN G. FINE, a citizen of the United States, residing at Yonkers, in the county of lVestchester, State of New York, have invented certain new and useful Improvements in Electrodes; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to electrodes and more particularly to electrodes adapted to be used as insoluble anodes in the electrodeposition of metals such as copper. The in-' vention has for its object the provision of an improved electrode for use in the electro-deposition of metals and more particularly the provision of an insoluble anode for use in the commercial electro-deposition of copper, especially from copper sulfate electrolytes containing chlorides and nitrates.

In the commercial electro-deposition of copper from copper-containing electrolytes using insoluble anodes, it is important that the anode possess certain properties if satisfactory results are to be obtained. The anode should be to a high degree insoluble in the electrolyte under the conditions prevailing during the electrolysis, or, in other words, the anode should possess high resistance to anodic disintegration. The anode should also have a low anodic potential in order to maintain the electrical energy consumption as low as possible. The anode, moreover, should not introduce by its disintegration or solution into the electrolyte salts which by their nature or quantity will materially contamlnate or fo1il the electrolyte and thus cause unsatisfactory operation. 0

The present invention contemplates the provision of an improved anode possesslng in a very satisfactory degree the aforementioned desirable properties. Thus, the anode of the invention is highly resistant to anodic disintegration and such disintegration as does occur during the electrolysis contaminates the electrolyte to a relatively small extent. And, in addition, the anode of the invention has a comparatively low anbde potential, whereby the power consumption per unit welght of metal deposited is correspondingly low.

Application filed February 18, 1921. Serial No. 446,070.

In the electro-deposition of copper from copper sulfate electrolytes, and in particular copper sulfate electrolytes containing chlorides and nitrates, ferro-silicon anodes have heretofore been largely employed in commercial practice. Such ferro-silicon anodes contain generally about 87% of iron and about 13% of silicon. Although spoken of as insoluble anodes, ferro-silicon anodes are disintegrated or corroded to a considerable extent during the electro-deposition of the copper from the electrolyte. As this disintegration of the anodes proceeds, the copper sulfate electrolyte becomes contaminated with metallic salts (principally iron sulfate) resulting from the solution of the anodes in the electrolyte.

The anodes of the present invention are composed principally of copper and are highly resistant to anodic disintegration, while such disintegration of the anode as occurs during the electro-depositionof copper contaminates the electrolyte to only a slight extent, because copper sulfate is the principal metallic salt going into solution as a result of such anodic disintegration.

As hereinbefore mentioned, the improved electrode of the invention is composed for the most part of copper and its most important constituents are copper, silicon and lead.

Lead does not alloy readily with copper, but I have found that it can be efi'ectively included in the electrode of the present invention by observing proper precautions. I have found it of advantage, both from the standpoint of the incorporation of the lead, and the electrode produced, to make use of a lead alloy containing the lead alloyed with some such alloying agent as calcium or barium or both. These alloying agents appear to be advantageous in the anode, and I believe that they assist in the alloying of the lead by serving as a bond or tie between the copper and the lead, although I do not desire to limit myself by any theoretical explanation of the @particular action "which takes place when these alloying agents are used. Magnesium and strontium may also be employed as the alloying agents in place of or in conjunction with barium or calcium, although magnesium is less satisfactory for the purposes in hand because it forms a soluble sulfate, whereas calcium,

barium and strontium form comparatively insoluble sulfates.

Instead of using lead alloyed with such alloying agents as those above mentioned, I have found it particularly advantageous to add lead in the form of lead sulfide. By introducing the lead in the form of lead sulfide or galena, I have found that it can be readily combined with the copper and silicon. The galena has a much lower specific gravity than lead itself, so that there is relatively little tendency for the lead to separate before it has an opportunity of alloying with the other constituents of the electrode. The use of galena as a source of the lead has the further advantages of low cost and availability. The addition of lead in the form of galena also results in giving increased strength to the anode.

In its broad aspect, the improved electrode of the invention may be considered as made of an alloy containing from about 15 to 25% of silicon, from about T}- to 10% of lead,

and the balance copper. In its preferred form, however, the electrode of the invention contains other metals which contribute in a large measure to the optimum results attained when the invention is carried out in its preferred form. Thus, the presence in the electrode of from 245% of manganese effects a material reduction in the corrosion of the anodes at the solution-air line.

It is one advantage of the anode of the present invention that it does not require pure copper for its production, but the copper used may contain other metals or elements, or other metals or elements may be present in the anode, without destroying its valuable properties. Elements such as tin, iron, tungsten, chromium, nickel, etc., may

thus, under certain conditions, be unobjectionable in the anode, or may even be advantageous therein.

In order to secure the aforementioned improvements of minimum contamination of the electrolyte, low anodic disintegration and low anode potential in the electro-deposition of copper from copper sulfate electrolytes (and in particular such electrolytes as also contain chlorides and nitrates) the anodes, in accordance with the present invention, are made from an alloy-containing copper, silicon, and lead, and preferably also manganese. I have found that an alloy composed of elements within the limits shown below has given good results:

Silicon 15-25% Manganese 215% 12-1O% Barium or calcium or both 0.01-10% Copper the balance.

copper and silicon may be first melted and then manganese and lead added thereto. The lead may be added in the form of an alloy with one or more of the aforementioned alloying agents (calcium, barium, etc.). Thus, the lead may be advantageously added in the form of an alloy containing 97% lead, 2% calcium and 1% barium.

I regard it as more advantageous, however, to add the lead in the form of its compound with sulfur, i. e., as galena, as above described.

If desired, the electrode may be made up by first forming copper silicide of a composition represented by the formula (Ju Si by the reaction between copper, silica and coke in the course of which the silica is reduced and the silicon thereof alloys with the copper to form copper silicide. anganese and lead (using the lead, e. g., with appropriate amounts of the aforementioned alloying agents or in the form of galena) may then be added to the resulting copper silicide or alloy of copper and silicon. Another meth- 0d of making the anodes is to form or melt the lead or lead-calcium or lead-calciumbarium alloy in a separate furnace and pour it into the mould simultaneously with the copper-silicon alloy, or the copper-siliconiron alloy, etc., preferably using graphite moulds. When the lead is added in the form of lead sulfide or galena, it can be added directly, in a finely divided state, to the molten copper silicon alloy and a suflicient opportunity given for the combination of the lead with the other constituents of the alloy.

I claim:

1. An electrode resistant to anodic disintegration and made up of an alloy composed for the most part of copper.

2. An electroderesistant to anodic disintegration and made up of an alloy com- 1posded principally of copper, silicon and 3. An electrode resistant to anodic disintegration and made up of an alloy composed principally of copper and silicon and containing lead and manganese.

4. An electrode resistant to anodic disintegration and made up of an alloy composed principally of copper, silicon and lead and containing lead and sulfur.

5. An electrode resistant to anodic disintegration and made up of an alloy composed principally of copper, :silicotn and lead together with a metal or metals of the alkali earth group.

6. An electrode resistant to anodic disintegration and made up of an alloy composed principally of copper and silicon and containing manganese, lead and sulfur.

posed principally of copper and silicon and containing manganese and lead together with a metal or metals of the alkali earth group.

8. An electrode resistant to anodic disintegration and made up of an alloy conpredominant amount, and

taining copper in 15 to 25% silicon.

9. An electrode-of the character specified in claim 5, containing 2 to 15% manganese.

10. An electrode resistant to anodic disin-,

tegration and made up of an alloy, containing copper in predominant amount, and g to 10% lead.

11. An electrode resistant to anodic disintegra-tion and made up of, an alloy conto 25% siliconand to 10% lead.

12. An electrode resistant to anodic disintegration and made up of an alloy comtaining copper in predominant amount, 15 a