JPS5959891A - Anode for electrowinning metal - Google Patents

Abstract

PURPOSE:To enable a drop in anode potential while reducing the amount of Ag, by adding a specified amount of Ca to a Pb-Ag alloy. CONSTITUTION:This anode for electrowinning metal is made of an alloy having a composition consisting of 0.2-2.0wt% Ca, 0.2-1.2wt% Ag and the balance Pb with inevitable impurities. By the composition the contamination of Zn or other metal deposited on a cathode with Pb can be reduced, and the anode potential can be dropped while reducing the amount of Ag. The anode is used to electrowinning metal in an acidic aqueous soln. of sulfuric acid.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an insoluble anode which can be used, for example, for dissolving metal 'dL in an aqueous sulfuric acid solution, and in this case can in particular be used to reduce the total anode potential.

Cathode if! In aqueous metal electrowinning in which the target metal is completely precipitated on a metal, it is most common to use VJ and ground carbon lead as the insoluble anode. , power),
In the case of an anode made of lead alone, lead elutes and forms on the surface, resulting in 1 ppb.
PB contamination of the precipitated metal becomes a major problem due to the falling off of the metal. For this reason, attempts have been made to use anodes made of various lead alloys. For example, it is 1ζ with all Ag added.

However, the lead alloy insoluble anode has a high anode potential, and has a low anodic potential as well as elution resistance and copper oxidation property, and the development of this anode is strongly desired.

The present invention was made with the aim of providing an insoluble anode that satisfies this requirement, and as a result of a series of small tests and research conducted in VC for this purpose, C! a Total 0.2-2.0
1 width of heavy piece, 1 piece of 4 pieces. When U ~ 20 tons 111φ and 8 [0.2 to 1.2 weight coefficient I"blc are added in a composite manner to form the anode, Pb will be added to the metal precipitated on the cathode.
One advantage is that the anode potential can be lowered while reducing contamination.

The insoluble anode of the present invention has a total of 0 Ca in the P11)-heg system.
．． 2 to 2.011, preferably 1.0 to 2.0
Although there is a large ti characteristic at the 1ζ point when the weight is added, when the total Ca addition is -1-, the anodic potential can be lowered than in the case of the PPb-7N system, and the (-force) is also in this case(
It was found that even if the amount of ΔR in the 'j, Y'■, + -Afl system was completely reduced, the effect of lowering the anode potential did not change significantly. Therefore, the previously attempted PI)-Ag
The above-mentioned objective can be achieved while reducing the total amount of Ag used compared to the system anode, and the amount of expensive Ag used can be reduced, which is economically advantageous.

1 Aroma electrode composition - 4-l/cvs, Ca-Pb1 alloy,
Ag-Pb1 alloy and pure lead, Ca; 0.2
~2.0 market volume ratio, Δg; 02~12 tonne volume ratio l
LC adjustment, put it in a graphite/L pot, melt and stir in an electric furnace, then put it into a steel mold VCrE with an all-anode shape and let it cool naturally.

Then, after strain removal, the obtained one anode was heated to 180
Annealing treatment at ~190C for about 2 days and nights (48 hours) f
,! f! One piece is good.

In the present invention, the Ca and Ag contents in the lead alloy constituting the anode are determined as described above. If the Ca content is less than 0.2 cm, no effect will appear on the low anode potential, and if it exceeds 2.0 cm, the 11th point will be 11!2+.
When used as an anode in an aqueous solution, it is not preferable because gypsum will precipitate, resulting in deterioration of conductivity when electricity is applied and a phenomenon of lead falling off. 1) If:
'f! The effect of lowering the r yang yin′ position is also small, while L
This is based on the reason that even if the content exceeds 2%, the effect of lowering the anode potential does not change, so the use of Ag is also uneconomical.

The effects of the anode of the present invention will be specifically illustrated below by giving representative examples.
child. The dimensions of each Yangsugi are 50mm (
Length) x 30+++ m (width) x 5 mm (thickness).

Before each anode is subjected to electrolytic treatment, the entire reaction surface is chemically treated.

For the electric 10-electrode test, two cathodes made of pure aluminum wafer are used for one piece of 19.
) An electrolytic cell with a tank volume of 500 cc was set with an electrode distance of 30 mm between the anode and cathode surfaces, and a zinc concentration of 6.
4fl, /1. Free sulfuric acid 156? /l sulfur j *
dIv lead water soluble nri'k '[! : As a solution, 'current density 45 mA/li, '+1. +9Ii' liquid 1=31c
The bath voltage (
V), the lead concentration (ppm) in the Schiff 1 zinc deposited in the yin and yang of the yin and yang is measured d1,
The results are listed in Table 1.

As is clear from the results in Table 1, the anode potential of the anode of the present invention is lower than that of the control example and the comparative example. As is clear from the comparison between Nα5 and N(16-8.11), the positive color potential is low even when the Ag content is low. 1゛1) Contamination in lead is also good Q
There are many cases.

To the example, g;
U, ε36, Ca; t, 96%, remaining 13 is a circle) 1* x 9 mm (thickness: 6) and a pure zinc cathode of the same size as the anode, in an electrolytic tank with a capacity of 3000 cc, 65 m ae 65 fi'/l, free sulfur (: fl 179'; I/1. (DfII zinc oxide aqueous solution electrolyte, distance between metal and yang 26.5 mm, 'current density 48 mA/c7, electric current density 1/1. '
1 rffmr 43 U, 24 hours' 11 I to 20
This electrolysis was carried out repeatedly /ζ, and the change in negative voltage over time was measured for each positive voltage VC, and the results are shown in Figure 1.

, As is clear from the results in Figure 41, 1]l)-・Ag
Compared to the Pb-Ag-Ca system of the present invention, the Pb-Ag-Ca system of the present invention
The hot water electrode has a low pressure at all times. This difference (/: is due to the two anode potentials under the same electrolytic conditions. This tendency continues over a long period of time. What is particularly noteworthy is that it remains unchanged.

[Brief explanation of the drawing]

Figure 1 shows the anode of the present invention and the anode of a comparative example.
This is a diagram showing the change in negative voltage over time when subjected to lI'l' conditions.

Claims (1)

[Claims] This is an insoluble anode containing all metals in an aqueous solution by electrolytic extraction.
An alloy for total metal extraction that is composed of Ca with a weight ratio of 0, Ag with a weight ratio of 02 to 1.2, and the balance being Pb and impurity elements unavoidably mixed in during manufacturing. (Enemy.