JPS58161787A - Electrode having lead base and manufacture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a dimensionally stable electrode, and more particularly to an electrode for generating oxygen from an acidic electrolyte used in methods such as electrowinning of metals from an acidic electrolyte. Regarding the anode.

BACKGROUND OF THE INVENTION Lead or lead alloy anodes have been widely used in the electrowinning of metals from sulfuric acid solutions. Nevertheless, such lead alloy anodes had significant drawbacks. The disadvantage is that
These include high oxygen overvoltage and loss of anode material, which leads to metal deposition on the cathode and contamination of the electrolyte.

Although the use of lead-silver alloy anodes reduces the oxygen overvoltage to some extent and improves the current efficiency, such anodes still suffer from the same overall drawbacks.

For the anodic generation of oxygen, it has been proposed to use dimensionally stable titanium anodes with a coating of platinum metal oxide, but generally speaking such anodes are more or less titanium-based Passivation and oxidation will occur.

It has also been proposed to apply protective undercoatings containing platinum-based metals to titanium bases below the external coatings, but such expensive coatings generally do not protect titanium pastes sufficiently. The meaning of using precious metals is lost.

Since metal electrowinning cells generally require a large anode area and operate at low current densities to uniformly electrodeposit the metal on the cathode, the cost of titanium-based cells can be significantly reduced. This is a factor that requires consideration.

US Pat. No. 8,682,498 describes a dimensionally stable anode having a mixed oxide coating containing platinum metal and pulp metal. One embodiment of the above-mentioned US patent relates to a method for producing a Ti-Pd mixed oxide fine powder that is later transformed into rod-shaped soft titanium through a rolling or hammer forging process.

However, in this way, the amount of precious metal included in the mixed oxide powder and applied to the electrode becomes prohibitively expensive for various industrial applications.

Thus, if the entire surface of the electrode is coated with mixed oxide powder, and if the electrode is operated at relatively low current efficiencies such as those used for metal electrode harvesting, the mixed oxide state The cost of precious metals used in this process becomes prohibitively high.

DISCLOSURE OF THE INVENTION One object of the present invention is to provide an improved anode for generating oxygen from acidic electrolytes.

Another object of the present invention is to provide an improved anodic reactive method for removing oxygen from an acidic electrolyte to substantially prevent loss of anode material and thereby eliminate the aforementioned drawbacks of conventional lead or lead alloy anodes. The object of the present invention is to provide an anode having a lead or lead alloy base that has electrochemical properties.

Yet another object of the invention is to provide a simple method of manufacturing such an electrode with improved properties.

The above aspects are substantially achieved by the present invention as defined in the claims.

The electrochemical properties of the anode are improved according to the invention as follows. That is, titanium particles catalytically activated by ruthenium oxide and partially embedded in the surface of a lead or lead alloy anode base and thus firmly fixed and electrically connected to said base are used as an anode. It applies to

The remaining unembedded portions of the catalyst particles protrude from the surface of the anode base, thereby providing a surface for oxygen evolution that has a larger area than the underlying surface of the lead or lead alloy anode base. I can do it.

The partially embedded catalyst particles described above are preferably arranged according to the invention for the following purposes: That is, to substantially cover the entire surface of the lead or lead alloy base, to provide maximum surface area for oxygen evolution, and thereby to substantially uniformly distribute the anodic current density.

According to the invention, it is particularly advantageous to use ruthenium to catalytically activate titanium particles. This is because ruthenium is an electrocatalyst for oxygen generation that is considerably cheaper and has excellent characteristics than other platinum metals.

Advantageously, the catalyst particles applied according to the invention consist of titanium sponge. Moreover, this catalyst particle is 1
In the range of 50 to 1250 microns, preferably about 300 to
It has a particle size in the range of 1000 microns.

In accordance with the present invention, the amount or load applied to a unit area of the anode base should generally be sufficient to substantially cover the anode base.

To produce electrodes with sufficient properties, typically 40
0 f! It has been found that relatively high particle loadings corresponding to more than 500 ml/m” are required.

Even higher loadings of 1000 g/m2 and above have proven to be advantageous as well.

, for catalyst particles, at most 6 of the weight of titanium in the particles
This is advantageous because the minimum amount of ruthenium corresponding to H is uniformly distributed over a wide area.

Nevertheless, as indicated above, e.g. 500-10
High loadings of catalyst particles, such as 0.00 g/m2, significantly increase the cost of ruthenium.

Therefore, it is particularly important to minimize the loss of ruthenium during anode operation.

It has been substantially determined that activation of titanium particles with manganese together with ruthenium in oxide form increases the stability of the catalyst towards ruthenium oxide alone or in combination with ruthenium oxide and other compounds.

Under conditions where oxygen evolves in an acidic medium, Ru-Mn
The improved electrocatalytic properties and stability of the oxide system are due to the particularly advantageous properties of the catalytically activated titanium particles used on the lead base according to the invention.

It has also been found that particle stability is further improved by pyrolytically forming titanium oxide on the activated particles.

Furthermore, if large activated particles are first pressed into the lead anode paste and then smaller particles, which advantageously have a higher ruthenium content than the larger particles, are pressed, the ruthenium can be utilized more efficiently. It has been confirmed that it is possible.

It has been found that such a two-stage welding process improves the long-term stability of the catalyst activation particles as well as the degree of contact of the catalyst activation particles with the lead paste.

It has also been found that the stability of the activated particles is further improved by carrying out a further pressure welding step to apply the deactivated particles of pulp metal or pulp metal oxide, specifically zirconium oxide. There is. This is particularly important in methods of electrowinning metals from electrolytes containing Mn2+ ions, where the precipitation of poorly conductive MnO2 impairs the anode properties.

The following examples illustrate various modes of carrying out the invention.

0.5'1g of RuC11s・αQ and 1.88g of un
An activation solution was prepared by dissolving CNO3)2.αq in 4 ml of 1-butyl alcohol. Next, this solution was diluted with 1-butyl alcohol in an amount six times the above amount.

& 25 g of Ti sponge (particle size >630 microns) was degreased with trichlorethylene and after drying was impregnated with the above activation solution. After each impregnation, the titanium sponge was dried at 100°C for approximately 1 hour. Next, heat treatment was first performed at 200° C. for 10 minutes, and then heat treatment was performed at 400° C. for about 10 minutes under an outside air flow. This activation step was performed five times. The Ru and Mn loadings thus obtained were 28.41QRu per I of Ti and 86.01n9 per g of Ti.
Reached un.

The same activation solution was now used on 4.9 g of Ti sponge (particle size 315-630 microns). The drying temperature, heating temperature and number of impregnations are the same as those applied in the previous case of large particles.

However, the heat treatment time at 400°C was 12 minutes. The amount of loading of Ru and Mn obtained in this case is T
27 rru per g of i; /8 per g of Ru and Ti
It reached 9Mn in 411.

These activated titanium sponge particles were pressed against a lead sheet coupon. That is, first, particles with large particle size (63
0 micron or more) with a pressure of 2901c9/cm2 to give 822 g/m2 and IL5g/m, respectively.
T per unit lead sheet area of 2 and 9.1 g/m2
The loading amounts of i, Mn and Rrt were obtained. Next, small activated titanium particles (315-630 microns) were added to the
Pressed with a pressure of 01c9/an2, respectively 4
00/l/m2.18°7El/m2 and 10.8
．． A loading amount of Ti, Mn and Ru of 9/m'' was obtained.

In this way, 722 g/m2Ti sponge, 1
9.9117m2Ru and 25.2,! i'/m
An electrode sample (Z, 62) was obtained with a lead paste uniformly coated with an amount of oxidized Ru-un activated titanium sponge particles corresponding to 2Mn.

The electrode sample was heated to H2S04 (1,50fj/1
3) was tested as an anode for oxygen generation. 50
The electrode potential (oxygen half-cell potential) at 0 A/m'' -flowing dust is 1.5 TV vs. NHH after 68 days of anode operation, and 19
° 1,59 V after 4 days and 1.7 after 210 days
It reached 5V.

Incidentally, 27.9 fj/m2 and 85.4g, respectively.
Another anode sample (Z, 61), obtained by pressing small particles of activated Ti sponge with high Ru and Mn loadings corresponding to 1/m2, directly onto lead, It showed an anode potential of 1.62V after 69 days of operation, and 1 when the anode operation was stopped after 194 days.
．． It showed a potential of 68V.

Furthermore, another anode sample (L76) was manufactured under the same conditions as Z,62. The only difference is that the activation process for large particles was repeated five times in L62, but only four times in L76. For Z, 76, the total RIL and Mn loadings are 22.1 g7m2 and 28.
Reached 0g/jou2. Similar tests on this anode showed 1.5V vs. NHE after 22 days of operation and 1.8V after 140 days of operation.

An anode sample (Z, 64) was manufactured under the same conditions as L62 of Example 1. The only difference is that the loading amounts of Ru and Mn were increased to 28.1 g/m2 and 29.8 g/ml, respectively. This anode was tested in a Zn electrowinning solution containing A/n2+ as the main impurity.

The potential after 60 and 120 hours of operation as an anode to generate oxygen from such a medium is 1.68 I/', respectively.
vs. NHE and reached 1°78V vs. NHE.

The current density was 40017 m2. During this period, no precipitation of manganese oxide occurred.

Incidentally, the total Ru and Mn loadings are 19 to 2, respectively.
After 60 hours of operation, a lead sample containing either only large-sized particles (680 microns or more) or only small-sized particles (815-630 microns), corresponding to 097 m2 and 24-25 fi/m2, 1.75V
It showed a high anode potential versus NHK. Thick anodic deposition of manganese oxide was also observed in the case of both particles.

Example □-5 A Ti sponge (particle size 315-630 microns) was activated under the same conditions as in Example 1. Next, use this Ti sponge.
42,717 m2.
Ti, un and Ru loadings corresponding to g/m2 were obtained. Finally, granular ZrO (particle size 150-500 microns) was added to the Ti at a pressure of about 410 kg/am2.
A Zr Ox loading amount corresponding to 2489/m2 was obtained by pressing onto the top surface of the sponge.

The electrode sample (L82) obtained in this way was
It was tested as an anode for oxygen generation in S04 (150 g/13). The electrode potential at a current density of 50017 m2 is 1.50 V vs. N after 150 hours of anodic operation.
Reached HE. After another 293 days, it reached 1.59V and was still operating. This corresponds to a voltage saving of 4 10 mV in the case of pure untreated lead.

Example 4 A Ti sponge (315-630 micron particle size) was first activated with a Rw and un containing solution as described in Example 1. The activation method was also the same as that shown in Example 1.

After such activation, a protective film is applied by impregnation with a Ti-butoxide-containing solution prepared by dissolving 1.789 Ti-butoxide in 3,75 iU 1-butyl alcohol and 0.251 HCl. Ta.

The sponge thus impregnated was dried at 100° C. for about 1 hour. Next, heat treatment was performed at 250° C. for 12 minutes, and further heat treatment was performed at 400° C. for about 12 minutes under an outside air flow.

Approximately 250 particles of activated titanium were prepared in this manner.
Then it was pressed onto the ship. As a result, 18.
8,! i' Rrt/m2.16.9, lit M
Electrodes with a lead base uniformly coated with an oxidized Ru-Mn activated titanium sponge with a protective layer of titanium oxide with an amount corresponding to 2.5.8 g Ti/d and 5159 Ti sponge/m” Sample CL84
) was obtained.

This 'electrode sample was converted into HxSCh (150g/8
) was tested as an anode for oxygen generation. 500
The potential at a current density of A/m2 reached 1.49 V vs. NHE after 130 hours of anodic operation. This corresponds to a savings of 510 mV when using untreated lead. The anodic potential further reached 1.64 V after 128 days. And this corresponds to a savings of 860 mV when using untreated lead.

Example 5 A Ti sponge (particle size 315-630 microns) was first activated with a Ru-containing solution prepared by dissolving 134 g of RuCβ8 #20 in 1e of butyl alcohol. Impregnation with such a Ru-containing solution, heating at 120° C. for 20 minutes to evaporate the solution, followed by a heat treatment at 250° C. for 15 minutes, and finally a heat treatment at 450° C. for an additional 15 minutes. I did this.

The impregnation, drying and baking steps were repeated four times.

The amount of ruthenium loaded in this way is 1g of Ti sponge.
The hit reached aolng.

After such activation, protection 1 of T t Q2 was applied to the activated particles by impregnation with a solution obtained by mixing 1.1i' of titanium butoxide with 8.751d of butyl alcohol. . The drying, knife heating and baking steps were the same as for the Ru-containing activation solution described above.

The activated titanium particles were placed on a lead sheet coupon at 250°C.
was pressed with a pressure of 97α2. In addition, 500 g
/m” particle loading, 159/m2Ru and 2.
Pressing was carried out such that 5 g/m2Ti was applied to the particles evenly distributed on the lead surface.

The cal electrode sample was heated to H2S04 (150El/e
) was tested as an anode for oxygen generation. 500
The electrode potential at a current density of A/m2 reached 1.66 V vs. NHE after 2000 h of anodic operation.

Example-6 Rutile T with particle size range of 513-630 microns
ie, the particles were impregnated with the following solution. That is, 0.5
IhbClls of 4Ii ・H2O, 1,89 butyl titanate, 0.251117 HCe and 3.75 m (
7) It is a solution of butyl alcohol.

After impregnation, the particles were air-dried at 100°C and then baked at 440°C for 10 minutes under a stream of air. This process was repeated four times. The obtained particles are A' u Q2
Activated with '7' c Oz.

The particles were pressed against a lead sheet coupon by applying a pressure of: 2501c9/an'. Particle loading amount is 1 each
A loading of 400 g/m2 was reached, corresponding to a loading of 5 g/m2 of Ru and 16 g/m2 of Ti. (RrbO, -TiO
Applicable as 2. ) 150 g of the thus obtained activated lead electrode at room temperature.
#! It was tested as an anode in an aqueous solution containing H2SO4. The applied anodic current density was 500 A/m
It was 2. 1.75 V after 300 hours of operation
The oxygen half-cell potential versus NHK was obtained. After 1000 hours, the anodic potential reached the same value as that of a pure, untreated lead anode.

- Husband” 1 case 7 An activation solution was prepared in the same manner as in Example 1.

The only difference is that in Example 1, it was diluted 6 times the amount.
In this case, the dilution was limited to three times the amount of violet in n-butyl alcohol.

Next, 411 g of Ti sponge (particle size 400-630 microns) was impregnated with the solution. After each impregnation, the titanium sponge was dried at 100° C. for approximately 1 hour. Next, 250
A heat treatment was performed at 400° C. for about 10 minutes, and finally a heat treatment was performed at 400° C. for about 10 minutes under an outside air flow. This activation step was performed three times. Ru and M thus obtained
The loading amount of n is 86.21N; l Ru7g Ti and 45.8 ml? Mn/9Ti was reached.

The activation step for the Ti sponge having a particle size of 630 microns or more in Example 1 was also performed using large particles (630 microns or more).
0 micron or more). However, the activation step was only repeated four times.

The load amount of Ru and un obtained in this way is 23.5■Ru
/flTi and 29.9 m9 Mnl 9 Ti were reached. ``The thus obtained activated titanium sponge particles are pressed onto the surface of the lead sheet coupon to partially embed it. Particles with a large particle size (630 microns or more) were pressed at the maximum W with a pressure of 240 kg/crn''.As a result, the particles were 8509/m'' and 10.59/m'', respectively.
/ m2 and 8.39/m" loadings of Ti, Mn and Ru per unit lead sheet area are given. As a result, 760 jj/m2 Ti sponge, 28.2 fi/m" are given.
An electrode sample (Z, 95) was obtained having a lead base uniformly coated with m"Ru and oxidized Ru-un activated titanium sponge particles in an amount corresponding to 29.8 g/m2un. Such an electrode sample was <(150,!i'
/e) was tested as an oxygen generating anode.

The electrode potential at a current density of 500 A/m2 reached 1.65 V vs. NHE at 287 days after anodization.

Incidentally, the small particles of activated Ti sponge are 28
15.4 g/ln" and 19.5 g/ln", respectively.
Another anode sample (Z, 98) with a loading of Ru and un corresponding to m2 was tested under similar conditions and found that 28
The electrode potential after 9 days was 1.78 V vs. NHK.

Furthermore, another anode sample (Z, 92) was manufactured under the same conditions as L95. The only difference is that the particle size is small (4
00 to 630 microns) was activated under the same conditions as Example 1 (Z, 62).

In this case, the total Ti, Mn and Ru loadings are 726 g/m', 22.59 /rn2 and 17, respectively.
．． It reached 7g/m2. 290 kg/an2 and 410 k, 97 for large particles and small particles, respectively.
The anode thus obtained was tested under similar conditions and showed a potential of 1.78 T' vs. NHE after 289 days of operation.

Example 8 An activation solution was prepared as in Example 7.

Next, 4.22,! i+ particles with large particle size (particle size 6
30 microns or more) was activated twice under the conditions specified in Example 7, thereby obtaining 21.5 m9 Ru, /9 T.
i and 27,41QMs/, pTi were obtained.

Another activation solution was applied to a Ti sponge with a small particle size range of 400-680 microns. This activation solution corresponds to the activation solution described in Example 7, except that it is diluted with twice the amount of ■-butyl alcohol. Two activations were then performed according to Example 7. 1
The loading amounts of Rrb and Mn per g of Ti are each 2
5.911& and 82.91nI;/Pi4sita.

The above particles with large particle sizes were first pressed together with a pressure of 210 Icg/d, and 36,097 m' and 9.8 m', respectively.
The anode sample (L1
20) was produced. Next, small activated titanium particles (400 to 630 microns) were pressed onto 820 at a pressure of 9Δ to produce 420g/m2.13゜9g, respectively.
/m' and 10.997 m2 of Ti.

A/? The loading amounts of L and Ru were obtained. The total loading of Ti, un and Ru thus obtained was 780g/each.
m2.28.797m2 and 18.697m2 were reached.

The cal electrode sample was heated to SO < (150g/13
) was tested as an oxygen generating anode. 500A
The electrode potential at a current density of /m'' reached 1.58 V vs. NHE after 218 days of anodic operation.

Example 9 Titanium sponge (400-630 microns) was oxidized 1
Oxidation was performed as shown below before activation with hb-un.

4.74 g of titanium sponge was activated once with the activation solution described in Example 1. 100% of this Ti sponge
After drying at 0.degree. C., heat treatment was performed at 400.degree. C. for 13 minutes under an outside air flow. The loading amounts of Ru and Mn are 5.2m9/gTi sponge and 6.6m9/9Ti, respectively.
It was a sponge. Source of outside air flow to such a sponge 4
A heat treatment was applied at 80° C. for 45 minutes, and the respective oxides were changed.

3.5 g of the Ti oxide sponge thus obtained was activated under the conditions described in Example 1. The only difference is that after each activation step, the intermediate heat treatment is performed at 25°C instead of 200°C.
This was done at 0°C.

The loading amount of un and Ru per 1g sponge is 8 each.
It reached 2.819 and 25.8 ■.

This pre-oxidized activated Ti sponge was press-fitted in two steps as follows. That is, first 280 Ic9/
am2 pressure and then 290 kg/am2 pressure to yield 21.1 g/m” and 16.6 g/m, respectively.
Obtain the Mn and Ru loadings of 2. The loading amount of this Ti oxide sponge reached 648 g/m''. Considering the loading amount of Mn and Ru in the Ti oxide before final activation, the total amount of
The loading amounts of vfn and Ru will reach 25.3 g/m2 and 19.99/m2, respectively.

This electrode was heated at 500 A/m in 15 fl/pH2SO4.
When tested at a current density of 2, the potential after 275 days of operation reached 1.65 V vs. NHK.

Example 10 A/n greater than the Mn1Ru ratio described in Example 1
Two types of solutions with a /Ru ratio were prepared as follows.

is on the right Mn (N03) 2 Q Understood.

It was diluted with 3 times the amount of n-butyl alcohol before washing.

Solution A corresponds to a molar ratio of Mn □z /Ru O2 = 4, and solution B corresponds to a molar ratio of Mn □z /Ru O2 = 9.
/corresponds to the ratio.

4.27 g of Ti sponge (particle size 315-630 microns) was impregnated with diluted Activation Solution A.

After each impregnation, the titanium sponge was dried at 100°C for approximately '1 hour. Next, heat treatment was performed at 250° C. for 14 minutes, and finally, heat treatment was performed at 400° C. for about 14 minutes under an outside air flow. This activation step was performed three times. The loading amounts of Rrt and Mn thus obtained were 29.8;/
Ru/9Ti and 63.8 me unl 9Ti were reached.

A 4.169 Ti sponge (particle size 315-630 microns) was impregnated with diluted activation solution B.

The activation step was carried out in the same manner as for activation solution A. The load amount of Ru and un obtained in this way is 19.9 m1
j/9Ti and 97.4m9M'n/gTi were reached.

The thus activated Ti sponge particles were pressed against a lead sheet coupon. Large particles (630 microns or more) activated in the same manner as in Example 8 were first
Welded at a pressure of 7 cm2, each
49/rn2.12.09/ln” and 9°49/m2
t) Ti, Kn, and Ru loading amounts per unit lead sheet area were obtained. Next, activated small Ti particles (315-630 microns) (in diluted solution A) were added to 85
0 kg/an'' pressure, and each
9997m2.25.5. ! iI/m2 and 11.79
A loading of 7 m2 of Ti, ufL and Ru was obtained.

As a result, 848 jj 7 m2 of Ti sponge, 2
Ru of 0.89/rn2 and hfn of 87.597m2
An electrode sample (Z, 164) with a lead paste uniformly coated with an amount of oxidized Rrb-Kn activated titanium sponge particles was obtained.

This electrode sample was tested as an oxygen generating anode in 150 g/β H2SO4. The potential at a current density of 500 A/m2 reached 1.50 V vs. NHE after 36 days of anodic operation.

For comparison, another anode sample (Z, 161) was fabricated. The preparation method consists of activated T (in diluted solution A)
820 kg/cm of small i-sponge particles
58,197 m2.
Ti equivalent to 15.697m2 and 84.097m2
This was done to obtain the loading amounts of %Ru and Mn.

When this electrode L161 was tested as described above, the operation was 7.
After 0 days, it showed a potential of 1.60 V vs. NHE.

In another set of experiments, Ti sponge particles with a particle size of 680 microns or more, activated as in Example 8, were first pressed together at a pressure of 280 kg/cm2, and each
2897m2.11.5 j;j 7m2 and 9.0.
9Ti, un and Rr per unit lead sheet area of 9/m2
The t loading amount was obtained. Next, activated titanium sponge particles with a small particle size (particle size 815-6
30 microns) at a pressure of 850 kg/CIn2, each 498 fl 7 m2.48.0 g/
- and 9.8 g/m2 of Ti, Kn and Ru loadings were obtained. As a result, 921 El 7 m2 of Ti, 59.
Electrode samples with a lead base (Li
2S) was obtained.

This electrode was tested as an oxygen evolution anode in HzSOa at 150.9/β. Potential after 33 days of operation is 1.5
It reached 7N' vs. NHK.

Another anode sample (Z, 162) was fabricated for comparison (with Li2S of Example 10). The manufacturing method consists of activated (in diluted Solution B) small particle size particles (315
~680 microns) were pressed directly onto the ship at a pressure of 9/c7n2 to 290 to produce 652 g/m2.18, respectively.
．． This was done to obtain Ti, Ru and un loadings corresponding to Ofi /m' and 68.6 g/rn''.

This electrode was tested in Ha S 04 at 150jj/13 and at a current density of 500A/rn2 and showed an actuation of 1
After 8 days (430 hours) it showed a potential of 1.74 V vs. NHE.

Example 12 0,54 g of IhbC8sC (38% Ru) and 0,121 PdC3z at 15 mA! Spot /L/
An activation solution was prepared by dissolving it in L:ff-/L/. This solution was stirred until all the salts were dissolved, then 1
．． 84 g of butyl titanate was added.

After impregnating 3.5 g of titanium sponge with a particle size range of 315-630 microns with this activation solution, 140
It was dried at 250°C for 20 minutes, then heat treated at 250°C for 15 minutes, and finally at 450°C for 15 minutes. All of these heating steps were performed in air. After cooling, the above impregnation, drying, and heat treatment steps were repeated six times. The amounts of Ru and Pd loaded on the particles thus obtained are a Ol1lii' Ru/gTi and 11 mgPd/
gTi has been reached.

500 g each of such activated titanium sponge particles
/m2 Ti, 15 g/m2 R wide 5.5. !
To obtain a Pd loading of 9/m2, 250 kg7
It was pressed onto a lead sheet coupon with a pressure of cm2.

f7) The electrode sample is H2S04 (150g/(1)
The electrode potential (oxygen half-cell potential) reached 1.78 V vs. NHK after 208 days of anode operation.

7g titanium sponge (particle size 315-680 microns)
was impregnated with a solution of 1,41 in which Ir in the form of IrC (3sC aqueous) was dissolved in isopropyl alcohol at a ratio of 7Q/WLt. After impregnating, this titanium sponge was heated at 140℃ for 1
It was dried for 5 minutes, then heat treated at 250°C for 10 minutes, and further heat treated at 450°C for 10 minutes. All these steps were performed in air.

The thus activated titanium sponge particles were exposed to 250 I
A pressure of C9/crn2 was applied to the lead sheet coupon. The particle amount can be selected from 700g/? 7+, 2
and a titanium and iridium loading of 1 g/m''.

A second activation solution was applied to the electrode samples described above as follows. First, 5.0g of un (NOx)*4H
, O and 0.8i Uo(NtJ3)26H20 as O,
A solution was prepared by dissolving Q+I+v in ethanol. This solution was applied to the surface of the electrode, dried at 140°C for 15 minutes, and then baked at 250°C (10 minutes) in air. After cooling, this coating, drying and baking process was repeated 5 times to finally deposit 240 g/- of MnO and 1
A loading of 2 g/m2 of cobalt oxide (calculated as C03Q4) was obtained.

The C(7) electrode sample was heated to H2S04 (150El'/
ll) was tested as an oxygen-evolving anode. 5
The electrode potential (oxygen half-cell potential) at a current density of 00 A/d was 1.78 volts (vs. M-IE) after 7 months of anode operation.
) reached.

(14~/Ru) and the impregnation process.

4. Repeat twice for a titanium sponge loading of 700 g/m2. ! This means that a ruthenium loading amount of i'/m'' was obtained.

When this sample was tested under the same conditions as in Example 18, the oxygen half-cell potential was 1.80 V after 6 and a half months of operation.
(vs. NHE).

9 Sn C13z 2 H2Q and 0.52 g M
n (NOs)! - An activation solution was prepared by dissolving 4H20 in 4 ml of butyl alcohol.

2.5 g of titanium sponge (particle size 315-630 microns) was impregnated with the above activation solution as follows. That is, 0.7'1 ml of the solution was uniformly applied to a titanium sponge, dried at 140°C for 15 minutes, and then heated at 250°C.
Bake for 110 minutes and finally bake at 420°C110
Baking was performed for 1 minute.

All of these drying and baking steps were performed in air. After cooling, the titanium sponge was activated again twice. Activation was performed using 0.5 d of activation solution each time. Then, it was dried and baked as described above.

The thus activated titanium particles were pressed against the surface of a lead-calcium alloy (0.06% Ca) coupon at a pressure of 250 to 9/d to obtain Ti'700fj/m2, Rt
20 j; l/m2, Sn5.8g/m2 and Mn1
A loading of 8.7 g/m' was obtained.

This electrode sample was tested as an oxygen-evolving anode at a current density of 500 A/m2 and in Halo < (150 fi / (3). The electrode potential reached 1,67 T/' vs. NHE after 7 months of operation. .

As can be seen from the above examples, the anode according to the invention can be formed in a simple manner and at a potential significantly lower than the anode potential corresponding to oxygen evolution in lead or lead alloys under similar operating conditions. Can be used for long-term oxygen generation.

It is noteworthy that when lead or lead alloy reference samples were tested under similar conditions, a significant amount of lead was lost from the electrodes when the electrolyte was observed; When such anode samples were tested as in the Examples above, no loss of lead from the base was observed.

Furthermore, when partially embedding the valve metal particles in the lead or lead alloy on the surface of the anode base, applying heat and pressure at the same time promotes fixation while simultaneously ensuring that the particles are completely embedded in the base. It has been found that the inconvenience of the base material being stuck and/or extending flat on the base is eliminated.

It is also noteworthy that the above embodiments can be further modified by determining the best conditions to give the anode according to the invention optimal stable electrochemical properties with maximum savings in the amount of precious metal. This is something that can be expected to improve.

In addition to using a press as in the above embodiments,
It is clear that the catalyst particles can also be applied and fixed to the lead or lead alloy base of the anode using any suitable means, such as pressure rollers, to obtain the essential advantages of the invention.

It has been found that the application of heat (eg, about 250° C.) during the welding process promotes partial embedding of the catalyst particles into the surface of the lead or lead alloy.

The present invention provides various advantages as described below.

(α) The anode according to the present invention can operate at a lower potential than that of conventional lead or lead alloy anodes used in industrial cells for electrolytically extracting metals from acidic solutions. Therefore, the cell voltage or energy cost for electrowinning metals can be reduced.

(b) Contamination of the electrolyte caused by materials coming out of the anode and precipitation on the cathode can be almost prevented. This is because it has been experimentally confirmed that oxygen is generated from the catalyst particles at low potentials which effectively prevents corrosion of the lead or lead alloy of the anode base.

(c) Resin-like crystals are formed on the cathode which causes a short circuit with the anode and burns out the pores leading to the anode, but no deterioration is observed in the properties of the anode according to the invention. This is because oxygen evolution from the catalyst particles occurs at low potentials that do not cause significant corrosion of any exposed lead or lead alloy base.

Since conventional lead or lead alloy anodes can be easily converted to improved anodes according to the present invention, industrial metal electrowinning cells can be modified to improve their properties in a very simple and inexpensive manner. It becomes possible.

(g) The low cell voltage obtained with the anode according to the invention can be easily monitored, so that any significant rise in the anode potential can be immediately detected. Therefore, the catalyst particles on the lead or lead alloy paste can be easily reactivated or replaced whenever necessary.

(a) When synthesized in a very small proportion with titanium sponge particles applied in many times the amount on a lead or lead alloy anode base, ruthenium can be used as a catalyst in the most economical way. Therefore, judging from the degree of improvement in the properties of the obtained anode, the cost of ruthenium is at a reasonable level.

(g) Ruthenium can be used in very low amounts and can be synthesized into inexpensive and stable materials.

(hl) Reduced short circuits are observed in copper electrowinning plants equipped with anodes according to the invention. This improves the current density at the cathode, thereby further increasing the energy savings already achieved by the low cell voltage of the present invention due to anodic operation at low oxygen half-cell potentials.

Industrial Applicability The anode of the present invention can be used to reduce the energy costs required for industrial electrowinning of metals such as zinc, copper, cobalt, and nickel and to increase the purity of the metal produced at the cathode. This is advantageous because it can be applied in place of the current lead or lead alloy anodes.

Such an anode is useful because it can be applied to various processes requiring oxygen generation at low overpotentials.

(3 other people)

Claims (1)

[Claims] (11) An anode for generating oxygen from an acidic electrolyte, comprising an anode base of lead or a lead alloy; (a) catalyst-activated titanium particles are uniformly distributed on the surface of the base; (b) The catalyst-activated titanium particles contain a small amount of ruthenium in the form of an oxide, which causes the lower part to be firmly fixed and electrically connected to the base. The lead or lead alloy remains electrochemically inert and thus essentially serves as a stable fJ inert current-conducting support for the catalytically activated particle reservoir, and at low potentials oxygen is generated by the anodic reaction. (2) The anode according to claim 1, characterized in that the particles are made of titanium sponge. 181 The anode is characterized in that the particles further contain manganese in the form of an oxide. (4) Catalytically activated titanium sponge particles of different particle size ranges are disposed on the base. The anode according to claim 2 or 3. (5) The anode according to claim 4, wherein smaller particles in the particle size range contain more ruthenium than larger particles. (6) The anode according to claim 1, characterized in that the activated titanium particles further contain titanium in the form of an oxide. (8) In addition to the activated particles, pulp metal and/or
Anode according to claim 1, characterized in that it comprises particles of or of a pulp metal oxide, preferably ZrO2. (9) The method for producing an anode according to claim 1, which (a) contains a small amount of ruthenium and manganese in the form of oxides obtained by thermally decomposing a ruthenium compound and a manganese compound applied to titanium sponge particles. , uniformly distributing catalyst activated titanium sponge particles on the surface of said anode base of lead or lead alloy; and (b) partially embedding said catalyst activated particles in said lead or lead alloy of said anode paste. A manufacturing method characterized by including the steps. (10) Large-sized activated particles are first pressed into the surface of the anode base, and then small-sized activated particles are pressed into the anode paste surface. Manufacturing method described in section. (11) The manufacturing method according to claim 10, wherein the particles with a smaller particle size contain more ruthenium than the particles with a larger particle size. ((2) the large particles have a particle size of more than 600 microns, and the small particles have a particle size of 800 microns or more;
12. Process according to claim 10 or 11, characterized in that it has a particle size in the range from ~600 microns. The manufacturing method according to claim 9, which comprises: (W) Forming ruthenium and manganese in the form of oxides on the catalyst activation particles, and then thermally decomposing the applied titanium compound to further form titanium oxide on the catalyst activation particles. Claim No. 9
Manufacturing method described in section. 10. The manufacturing method according to claim 9, wherein the activated particles are partially embedded, and thereafter, particles of pulp metal and/or pulp metal oxide are further press-fitted into the anode base. (g) partially embedding the catalyst-activated titanium particles;
16. The manufacturing method according to claim 15, wherein the zirconium oxide particles are then crimped onto the anode base and similarly fixed. (17) In an electrode containing a lead or lead alloy paste and a catalyst for carrying out an electrochemical reaction, catalyst particles made of an inert super heat-resistant oxide activated by the desired reaction catalyst are uniformly spread over the surface of the paste. distributed and partially embedded so that the particles are firmly fixed and electrically connected to the paste, and furthermore the lead or lead alloy in the lower layer of the paste remains electrochemically inert and thus An electrode characterized in that the desired electrochemical reaction is carried out on the catalyst particles at a potential that substantially serves as a stable, inert, current-conducting support for the catalyst particle reservoir. (a) The electrode according to claim 17, characterized in that the inert super heat-resistant oxide particles are activated by a catalyst containing a noble metal. (g) The super heat-resistant oxide particles are rutile-like Claim 17 or 18, characterized in that it is titanium oxide.
Electrode as described in Section. (Support) ■ A method of using the electrode according to claim 17 as an anode for generating oxygen from an acidic electrolyte.