JPH04301092A - Cathode for forming electrodeposited film and method for producing electrolytic powder using the same - Google Patents

Abstract

PURPOSE:To drastically improve production capacity per installation space by constructing plural bar-shaped electrodes in a specified relation. CONSTITUTION:Plural electrodeposited films forming bar-shaped electrodes 4 installed between an upper aligning plate 2 and an under aligning plate 3 are used as cathodes. An equipment is constructed under a established relation in which (d), a distance between bar-shaped electrodes, is expressed as 2r1<=d<(npi-4).(r1+r2)/(n-1), when number and a radius of bar-shaped electrode are (n) and r1 respectively, and a thickness of an electrodeposited layer stably formed on bar-shaped electrodes is r2.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to the production of metal powder or conductive powder by depositing an electrodeposited film by electrolysis and recovering it.

0002

2. Description of the Related Art There are various methods and apparatuses for producing metal powder and conductive powder (hereinafter referred to as metal powder) by electrolysis. For example, those using rotating cylindrical electrodes,
It uses rod-shaped electrodes. However, in order to increase productivity, it is necessary to alternately install a flat anode and a flat cathode in a rectangular parallelepiped electrolytic cell, perform electrolysis, and scrape off the dendrite-like deposits etc. deposited on the cathode with a scraper. is common.

By the way, when metal powder is deposited on the surface of a cathode, the deposited metal powder itself functions as a cathode. As a result, the growth of the metal powder itself occurs preferentially, and the unevenness of the cathode surface becomes more severe as the electrolysis time increases. However, the metal powder itself is usually not strongly bonded to the cathode surface structure, so
When the metal powder exceeds a predetermined weight, it will naturally peel off and fall. Thereby, metal powder can be recovered.

0004

[Problems to be Solved by the Invention] However, in this method, if the metal deposition rate is too fast, the electrolyte will be encapsulated in the resulting metal powder, resulting in a decrease in quality. Furthermore, if the overvoltage is too high, impurities in the liquid will precipitate at the same time. Therefore, with this method, it has been difficult to increase the deposition rate and overvoltage to achieve even higher efficiency.

An object of the present invention is to provide a method that is more efficient than the conventional method for producing metal powder or conductive powder by an electrolytic method using a conventional rectangular parallelepiped electrolytic cell and a flat anode. The purpose is to provide a cathode for use.

[0006]

[Means for Solving the Problems] The cathode of the present invention which solves the above problems has an upper alignment plate, a lower alignment plate, and a plurality of electrode-deposited electrodes provided between the upper alignment plate and the lower alignment plate. A cathode consisting of rod-shaped electrodes for film formation is used, and the cathode is stably formed on the rod-shaped electrodes, with the distance between the rod-shaped electrodes being d, the number of rod-shaped electrodes being n, and the radius of the rod-shaped electrodes being r1. When the thickness of the electrodeposited layer is r2, d is 2r1
≦d<(nπ-4)・(r1 +r2)/(n-1)
It is configured to satisfy the following relationship.

Furthermore, the production method of the present invention uses the cathode as a cathode for producing electrolytic powder. The upper alignment plate is connected to a hanger, and a conductive bar (not shown) is passed through the hanger. The rod-shaped electrode is arranged vertically when attached to the electrolytic cell so that electrodeposits can be removed from the surface of the rod-shaped electrode.

[0008]

[Function] In the present invention, the material of the hanger, each alignment plate, and the rod-shaped electrode is selected depending on the liquid properties of the electrolyte and the adhesion to the target metal, but stainless steel, titanium, etc. are generally used. Moreover, although it is preferable that the rod-shaped electrode has a circular cross section, other shapes may be used without any problem. In this case, for example, if it is an ellipse,
r1 is 1/2 of the major axis.

[0009] In the present invention, when rod-shaped electrodes are placed adjacent to each other to form a cathode, an electrodeposited layer is also formed in the gap between the rod-shaped electrodes, so that the electrode area is substantially smaller than that of a plate-shaped electrode housed in the same volume. Based on the fact that it becomes larger.

Hereinafter, according to FIG. 4, the distance d between the rod-shaped electrodes,
The relationship among the number n of rod-shaped electrodes, the radius r1 of the rod-shaped electrodes, and the thickness r2 of the electrodeposited layer stably formed on the rod-shaped electrodes will be explained.

FIG. 4 is a schematic diagram showing a cross section of a rod-shaped cathode 4, and an electrodeposited layer 5 of precipitated metal is attached along the surface of the rod-shaped electrode 4. As shown in FIG. r1 is the radius of the rod-shaped electrode 4, and r2 is the thickness of the electrodeposited layer 5 stably formed on the rod-shaped electrode 4. The actual electrode area Sb of the rod-shaped electrode 4 in which electrodeposition has reached a steady state in this way is Sb = 2nl, where the length of the rod-shaped electrode 4 is l and the number of rod-shaped electrodes 4 is n.
π(r1 +r2). On the other hand, the rod-shaped electrode 4
When the distance between them is d, the thickness is 2r1, the width is d(n-
1)+2r1, the actual area S of a flat plate electrode with length l is S=
(2d(n-1)+8(r1+r2))·l.

In order to achieve the purpose of the present invention, that is, to improve productivity and to allow more current to flow without increasing the overvoltage applied to the cathode, the actual area Sb of the cathode is
It is necessary to satisfy the relationship >S. Therefore, 2n
lπ(r1 +r2)>(2d(n-1)+8(r
1+r 2))・l. Simplifying this formula, we get (
nπ-4)·(r1 +r2)>d(n-1). On the other hand, d does not become smaller than 2r1. As a result, in order to achieve the object of the present invention, d must be 2r1 ≦
The relationship d<(nπ-4)·(r1 +r2)/(n-1) must be satisfied.

[0013]

[Embodiments] Hereinafter, embodiments of the present invention will be explained with reference to the drawings. FIG. 1 shows an example of the cathode of the present invention, and shows an upper alignment plate 2 provided with hangers 1 and 1', a lower alignment plate 3, and a gap between the upper alignment plate 2 and the lower alignment plate 3. , upper alignment plate 2
The cathode is made up of a plurality of rod-shaped electrodes 4 provided at right angles to the cathode. Conductive bars (not shown) on the hangers 1 and 1'
is connected.

[0014] When the cathode is installed in the electrolytic cell, the rod-shaped electrode 4 is oriented vertically, and the reason for doing so is to prevent the generated electrolytic powder from falling.

FIG. 2 is a side view of the cathode of FIG.
2 is a perspective view showing the lower end of the rod-shaped electrode 4 attached to the lower alignment plate 3. FIG. The lower end of the rod-shaped electrode 4 is inserted into the hole 3a on the upper surface of the lower alignment plate 3 and joined by welding or screws. The upper ends of the rod-shaped electrodes 4 are attached alternately to the left and right sides of the upper alignment plate 2 to provide left-right symmetry in the distribution of the rod-shaped electrodes 4, to prevent tilting when hanging, and to increase the actual electrode area. , and to make it easier for the electrolytic powder to fall. Correspondingly, the arrangement of the holes 3a is also shifted left and right with respect to the axis of the lower alignment plate 3.

The present invention will be further explained below with reference to examples of electrolytic cells using the cathode according to the present invention.

[0017] Width 740 mm, length 900 mm, surface area 80 dm2 formed by three insoluble anodes made of Ti mesh coated with ruthenium oxide and 48 rod-shaped electrodes made of Ti with a diameter of 6 mm.
The two cathodes and the anode, cathode, and
The anode, cathode, and anode were attached in this order. The cathode rod-shaped electrode is
It was constructed as shown in FIGS. 1 to 3. 35ml/ into the electrolytic tank
Ni: 190-240g/l, Cu: 4 in A/H ratio
While supplying a chloride-based electrolytic solution of 0 to 50 g/l, pH: 1, temperature: 60°C, constant voltage electrolysis was performed at an interelectrode voltage of 3.1 V and 3.5 V to obtain electrolytic copper powder. .

[0018] Next, the width is 740 mm, the length is 900 mm,
Electrolytic copper powder was obtained in the same manner using a Ti flat plate electrode with a surface area of 150 dm2 as a cathode.

[0019] Analyzing the Ni grade in the obtained electrolytic copper powder,
The relationship between this value and the current value when copper powder was obtained is shown in FIG.

The above electrolysis conditions are conditions that increase the possibility that a large amount of Ni will be mixed into the copper powder obtained. Under such conditions, the advantages of the present invention can be evaluated by comparing the situation of Ni contamination. In other words, in FIG. 5, if the same level of Ni quality is allowed, using the rod-shaped cathode (○●) according to the present invention will produce a much larger current than using the flat plate electrode (□■) as the cathode. It can be seen that it is possible to flow

Since the electrolysis conditions of this example are constant voltage electrolysis of approximately 3.1 V, it seems that the large amount of current indicates that the substantial electrode area is large. Therefore, in the above examples, it can be said that the cathode of the present invention has a larger substantial surface area than the flat plate cathode.

Further, FIG. 6 shows the change over time in the total current value in this example. In FIG. 6, the curve of the rod-shaped cathode intersects the curve of the plate-shaped cathode at the elapsed time of 10 hours, and it can be said that the cathode of the present invention has a larger substantial electrode area after 10 hours. In FIG. 6, r2 is estimated from the equilibrium current value to be approximately 2 mm. Since the value of r2 varies depending on the composition of the electrolytic solution used, that is, the composition of the solution containing the target metal and the electrolytic conditions, it is desirable to obtain it in advance.

In this example, it was found that when a rod-shaped electrode was used as the cathode, the convection state of the liquid was better and the concentration gradient on the cathode surface was smaller. This also causes the precipitation of Ni into the deposited copper to further decrease.

[0024]

According to the present invention, the substantial electrode area can be increased, and as a result, the production capacity per installation area can be greatly increased. Moreover, the quality of the metal powder and conductive powder obtained in this way is expected to be higher than conventional ones.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an example of a cathode used in an embodiment of the present invention.

FIG. 2 is a side view of the cathode of FIG. 1;

FIG. 3 is a perspective view partially showing the lower end of the cathode in FIG. 2;

FIG. 4 is a cross-sectional view schematically showing how an electrolytic membrane is formed on the cathode of the present invention.

FIG. 5 is a graph showing the relationship between the Ni grade in the electrolytic copper powder obtained in the example of the present invention and the current value at the cathode when the electrolytic copper powder was obtained.

FIG. 6 is a graph showing a change in total current value over time in an example of the present invention.

[Explanation of symbols]

1, 1' Hanging hand 2 Upper alignment plate 3 Lower alignment plate 4 Rod-shaped electrode

Claims (2)

[Claims] 1. A cathode comprising an upper alignment plate, a lower alignment plate, and a plurality of rod-shaped electrodes for forming an electrodeposited film provided between the upper alignment plate and the lower alignment plate, wherein The distance is d, the number of rod-shaped electrodes is n, and the radius of the rod-shaped electrode is r1.
The thickness of the electrodeposited layer stably formed on the rod-shaped electrode is r
2, d is 2r1≦d<(nπ-4)・
A cathode for forming an electrodeposited film, characterized in that it is configured to satisfy the relationship (r1 +r2)/(n-1). 2. A method for producing electrolytic powder, comprising using the cathode according to claim 1.