DE1202005B - Process for electrorefining nickel - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

C22d

German class: 40 c-1/14

Number:
File number:
Registration date:
Display day:

1202005
J27340VI a / 40c
January 15, 1965
September 30, 1965

The most common method currently used to refine nickel is to refine the metal to deposit cathodically on thin starting sheets and in this way to form large cathode plates. The deposited nickel 5 adheres inseparably to the starting sheets, which are thus an integral part of the finished sheet Represent plates. This method has two disadvantages. Once a new starting sheet must be in a separate one for each cathode plate to be produced Operation to be established. On the other hand, the cathode plates are determined by the dimensions the electrolytic cell in which the process is carried out is too large for many purposes, so that the panels must be cut up before they can be used. Since the panels are generally 10 to 12.5 mm thick and 600 X 900 mm, heavy scissors are necessary.

To avoid this latter disadvantage, British Patent 740,581 suggests both One or more lines on the sides of the original sheets

or to provide strips of non-conductive material,

the lines on one side being the same

Places are, as on the other side, in order to this according to the invention it is important that the nickel-low-way in the finished plates weakened lines 25 is only half-adherent. This means that or strips, ie predetermined breaking points, are to be formed. To
as before, however, is the effort to break the
whole plate into smaller pieces quite considerably.
There is also a new one for each record
Starting sheet necessary.

According to the invention in the electrorefining of nickel as a shaped body - in the further description called "Former" for short - which is connected as a cathode, a flexible sheet of metal used, on the surface of which electrically conductive islands by interconnected lines or Strips of non-conductive material are defined. Nickel is grown in considerable thickness on these islands semi-adherent electrodeposited, and method of electrorefining nickel

Applicant:

International Nickel Limited, London

Representative:

Dr.-Ing. G. Eichenberg

and Dipl.-Ing. H. Sauerland, patent attorneys,

Düsseldorf, Cecilienallee 76

Named as inventor:

Burton Bower Knapp, Allendale, N.J.

(V. St. A.)

Claimed priority:
V. St. v. America January 17, 1964
(338 309)

the precipitate remains attached to the former during the deposition process, but thereafter can be separated using mechanical means. This point of view must be with the Selection of the material for the former must be observed. Preferably one for the former Nickel-chromium or nickel-chromium-iron alloy used containing 8 to 30 ° / o chromium, at least Contains 8% nickel and up to 74% iron, for example stainless steel type 18-8. Instead of this rolled nickel or nickel obtained by precision electrolytic forming can be used, provided its surface is first passivated, for example by immersion in an aqueous solution

Although from a bath that contains a certain amount of a solution of 0.1 to 1 g of dichromate per liter for the

Contains stress-reducing agent that has the effect of relieving internal stress in the precipitate to keep it low. After removing the former electrolytically coated with nickel Duration of about one minute and subsequent washing in water. This treatment can too applied to formers made of nickel-chromium and nickel-chromium-iron alloys and contributes to

The deposited nickel will easily extend the life of the bath. detached by bending the former. By suitable the former must be so thick that it has the necessary

Choosing the size of the electrically conductive islands will this way the nickel in pieces of any desired Preserved size, while the formers remain reusable.

In contrast to the usual electric refining, like

As described above, it is strong enough for the process, but also thin enough to be to be easily bendable. Useful thicknesses are between 0.5 and 1 mm.

The material between the islands can be made of any electrically non-conductive material, such as paint, Varnish, varnish, tape or the like., Exist on the

509 689/343

Surface of the former adheres and is compatible with the electro refining bath. Suitable substances include also those based on plastic or rubber, for example ethoxylin synthetic resins, polyethylene or the acrylic resins. The non-conductive material can be attached to a flat side of the former will. However, preference is given to a surface that is embossed with a hollow system, one below the other connected lines or strips is provided, so represent beads, which with the non-conductive Fabrics are filled or covered and at the same time mechanically stiffen the former. Embossed Sheets of this type are expediently produced by electrolytic precision forming, for example made of nickel. The former can then with particular advantage from two such hollow embossed Sheets are assembled, which lie with their backs against each other, so that the nickel can be knocked down on both sides at the same time.

The lines or strips of non-conductive material are preferably at least as wide as that the metal to be deposited is thick, in order to reduce the tendency of those on neighboring islands nickel deposits are formed to bridge the gaps and adhere to one another.

It is also important that the nickel be deposited in a low internal stress condition. A high internal stress precipitate, such as that produced in a conventional Watts bath, which normally produces precipitates with an internal stress of about 1400 kg / cm ² , has a tendency to separate from the former before it reaches the desired thickness is, a tendency that increases with the size of the islands. The lower the internal stress, the larger the islands can be chosen on which the nickel is deposited. The bath composition must therefore be related to the size of the islands so that the voltage in the precipitate is sufficiently low to prevent separation from occurring before the precipitate has grown to the desired thickness. It is advisable to ensure that the tension does not exceed 350 kg / cm ² . Then it is possible to form precipitates 6-10 mm thick on islands of 25 cm ^2. Such low voltages in the precipitate can be obtained by adding 0.05 to 0.5 g / l of an aromatic sulfo compound to the electrolyte, for example p-toluene sulfonamide, benzenedisulfonic acid, naphthalenetrisulfonic acid or saccharin. Any of the baths conventionally used for electrorefining, for example a sulfate bath, a sulfate chloride bath, a chloride bath, a sulfamate bath, a sulfate sulfamate bath or a chloride sulfamate bath, can be used as the electrolyte.

The process of electroplating is continued until the nickel is in the desired, mostly considerable thickness is deposited. In general it can be said that the thickness is at least Is 1.5 mm and can rise to a maximum value from the level of the internal mechanical Voltage and depends on the size of the islands and in any case be 12.5 mm or even more can.

In order to remove the precipitate, the former only needs to be bent in some suitable manner be, for example, by running it between rubber rollers. Are the lines or Strip of non-conductive material wide enough so that the precipitate dissolves into its individual islands, when it is removed from the former. In any case, the pieces are easy to separate from one another.

The following examples serve to further

Explanation of the invention.

ίο Example 1

A stainless steel former 0.8 mm thick to be used as a cathode was provided with interconnected lines or strips of electroplating tape which were at least 3 mm wide. These lines divided the areas into electrically conductive islands in the form of squares with an edge length of 6 and 12 mm on one side and in the form of circular areas with a diameter of 6, 9 and 12 mm on the other side. After degreasing, the former was electroplated with nickel to a thickness of 3 mm on both sides at a current density of 0.022 A / cm ² and a temperature of 66 ° C. in an aqueous bath suitable for electrorefining of nickel. This bath had a pH of 4 and contained

Nickel (as sulphate) 60 g / l

Chloride (as nickel chloride) 10 g / l

Chloride (as sodium chloride) 40 g / l

Boric acid 20 g / l

p-Tolucl sulfonamide 0.2 g / l

Wetting agent (sodium lauryl sulfate) 0.2 g / l

When the galvanized formers taken out of the bath were bent, the one separated Nickel coating in the form of individual pieces.

Another stainless steel flat former 0.8 mm thick was placed on both sides by means of lines or strips of non-conductive, 6 mm wide tape into square islands of 12 mm Split edge length. The former prepared in this way was used under the same conditions as in example 1 nickel deposited, but up to a thickness of 4.5 mm on each side. At this Thick lines or strips of non-conductive tape were bridged by the nickel. Of the galvanized former was taken out of the bath and removed to remove the precipitate bent. The precipitate could then immediately follow the original lines of non-conductive Tape attached to the former simply by dropping it on a cement floor to get broken.

The precipitates generated in the two examples had an internal tensile stress of 70 kg / cm ² and were smooth and white.

In carrying out the method of the invention in a given electric refining cell can work with a higher current density than with the usual method with starting sheets, in order to avoid the reduction in the caused by the non-conductive material in this way Equalize the cathode area and according to the precipitation capacity.

Through the use of sulfur-containing stress-relieving ingredients, e.g. B. p-To-

luenesulfonamide, in the electrorefining bath according to the invention, are formed in the precipitate small amounts of sulfur, e.g. 0.015 to 0.05%. The pieces obtained are suitable particularly good for use as coating material 5 in the production of nickel coatings, for example in titanium baskets, since they are highly active, corrode uniformly and with increasing corrosion settle evenly in the basket, so that the sticking, the bridging and the formation of holes in the nickel material within the basket is reduced to a minor degree or entirely be avoided.

Claims (5)

Claims: * 5 1. Process for the electric raffullerene of Nickel by electrolytic deposition of nickel in considerable thickness on electrically conductive Islands formed by interconnected lines or strips of non-conductive Material formed on the surface of a shaped body connected as a cathode made of sheet metal are characterized by the use of a flexible molded body on which the nickel is deposited semi-adherently and with low internal tension, whereupon the deposited nickel is removed by bending the shaped body outside of the bath. 2. The method according to claim 1, characterized by the use of a molded body passivated nickel or a nickel-chromium alloy or a nickel-chromium-iron alloy. 3. The method according to claim 1 or 2, characterized in that the non-conductive material is applied to interconnected lines or strips that bead-like on the are embossed on one side of the molded body. 4. The method according to any one of claims 1 to 3, characterized in that the lines or strips of non-conductive material are at least as wide as the one to be produced Nickel deposit is thick. 5. The method according to any one of claims 1 to 4, characterized by the use a bath containing 0.05 to 0.5 g of an aromatic sulfo compound per liter.