JPS63247389A - Method for electrolytically refining copper - Google Patents

Abstract

PURPOSE:To improve the productivity of the electrolytic refining of copper by washing a crude copper plate as the anode with an acidic soln. or water to remove copper oxide and foreign matter sticking to the surface of the anode and by using the anode for electrolysis. CONSTITUTION:When copper is electrolytically refined, a crude copper plate as the anode is washed with an acidic soln. such as an electrolytic soln. or water to remove copper oxide and foreign matter sticking to the surface of the anode and the anode is used for electrolytic refining. Thus, uniform conditions during electrolysis are ensured because powdery copper and foreign matter are not present near the anode immediately after the beginning of electrolysis, so normal electrodeposition on the cathode is carried out from the beginning of electrolysis and the current efficiency and productivity can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application> The present invention relates to a method for electrolytic refining of copper that improves productivity.

<Prior art> Copper electrolytic refining involves using an acidic solution mainly composed of sulfuric acid and copper sulfate as an electrolyte, and alternately placing a blister copper plate anode and a pure copper (usually electrical steel) thin plate cathode in an electrolytic tank. This is done by arranging and charging the electrodes and applying a positive current to the anode and a negative current to the cathode.

The quality of the blister copper plate, which is the raw material for this electrolytic refining, is 98-99.
A product containing 8% Cu and impurities such as silver and lead can be obtained.

As a guideline for operational performance in copper electrolytic refining, in addition to the quality and impurities of the product electrolytic copper, the percentage of effective current (current efficiency - %), and the amount required to obtain 1 ton of electrical steel. Power consumed (power unit: KWH/electrolytic copper),
The amount of current per unit surface area of the cathode (or anode) (current density: A/rn"), the degree to which the anode and cathode are packed into the electrolytic cell (pressure between the electrodes M: -), etc. determine productivity, product quality, cost, and energy. It is taken up as a characteristic value that represents aspects such as efficiency, and is subject to management.

Until now, various measures have been taken to improve productivity, product quality, energy efficiency, and reduce costs. Since there are some methods that have contradictory effects such as deterioration of product quality when increasing the temperature, technological improvements have been made to eliminate the negative effects of each measure and maximize the positive effects. .

Among other measures, the first requirement for improving the operational performance of copper electrolytic refining is to use a high-quality blister copper plate anode. The quality of the blister copper plate anode is as follows:
It is required that the chemical composition of impurities etc. be within a specified range, that it be manufactured to the correct shape and dimensions, and that it be correctly vertical when charged into the electrolytic tank. Various methods have been used to control the quality of blister copper plates.

For example, in order to increase the current density and shorten the distance between electrodes, which will lead to improved productivity and energy savings, the perpendicularity of the anode and cathode has been further improved. Because of this, the current density is approximately 240 A/m as the upper limit for unidirectional current, but by periodically passing reversal current, the current density can be increased to 350 A/m.
It has been implemented to increase the temperature up to A/m'.

However, demands for improving operational performance in copper electrolytic refining have become more severe in recent years, and further increases in productivity are required.

<Problems to be solved by the invention> In order to further improve operational performance in response to the recent strict demands for copper electrolytic refining as described above, it is necessary to eliminate It has been found that it is generally effective to use the blister copper plate anode for electrolysis after removing copper oxides and foreign matter from the electrode surface.

In other words, when electrolytically refining a blister copper plate anode with copper oxides and foreign substances still attached, the surface Due to the influence of powdered steel produced by the reaction between oxide and electrolyte and foreign matter peeled off from the surface, uneven electrolytic conditions occur and abnormal electrodeposition occurs on the cathode surface, resulting in a decrease in current efficiency and damage to the product. It may cause quality deterioration.

The present invention provides a method for producing copper that achieves even better operational results in terms of productivity, product quality, energy efficiency, and cost by electrolytically refining the copper oxide and foreign matter on the surface of the blister copper plate as described above. The purpose of this invention is to provide an electrolytic refining method.

Means for Solving the Problems> The steel electrolytic refining method of the present invention for solving the above objects is as follows:
In a copper electrolytic refining method in which a blister copper plate is electrolytically refined in an acidic solution using a blister copper plate as an anode, the anode is washed in advance with an acidic solution or water to remove copper oxides and foreign matter adhering to the anode surface, and then electrolytically refined. It is characterized by being made available to the public.

<Operation> The blister copper plate anode is used for electrolytic refining after copper oxides and foreign substances adhering to the surface have been removed by dissolving and cleaning with an acidic solution or peeling and cleaning with water. Uniform electrolysis conditions are not disturbed by powdered steel or foreign matter near the anode. Therefore, normal cathode electrodeposition occurs immediately after the start of electrolysis.

<Example 1> One example is 99.2% Cu, 0.15% pb.

0.1%As, 0.02%sb, o, oos%Bi.

141 blister copper plate anodes of 0.049%AgJo, )
The anode was filled with the same electrolytic solution (at a temperature of 50 to 60°C) and left overnight to remove copper oxide and foreign matter from the anode surface. The anodes were placed in three electrolytic cells alternately with the cathodes.
/r11'', distance between poles 11 fl (between the centers of adjacent anodes and cathodes, hereinafter referred to as side i)) 100 m, (2) current density 350 A/rn'', distance between poles 96 cylinders, (
3) Current density 370A/rn'', distance between poles 100m 3
Electrolysis was carried out under specific conditions and according to the electrolysis conditions table.

At the same time, a blister copper plate anode whose surface was not washed was similarly electrolyzed under three conditions for comparison.

The electrolysis results are shown in Table 2 (electrolysis result table of Example 1). Note that the obtained electrolytic copper was 99.99% Cu, and there was no difference.

As can be seen from Table 2, in the periodic reversal current method, when the current density is 350 A/m'' and the interelectrode pressure is 9100 corners, the current efficiency is 94.0% for the anode without surface cleaning, as before. For the anode cleaned according to the present invention, it was 95.3%,
This is an improvement of 1.3%. When the distance between the electrodes is shortened to 96 mm at the same current density of 350 A/go, the current efficiency is 92.2% and 9 for the unwashed anode and the washed anode, respectively.
4.8%, an improvement of 2.7%. Also, the current density is 37
If raised to 0 A / rrl'', the same (91,5
% and 95.2%, which is an improvement of 3.7%.

Table 1 Electrolysis conditions table Electrolysis M temperature 65℃ Electrolyte composition Cu 47.2 g/lH3
O195g/j As 6.7 g/e Sb 0.4 g/I Bi 0.1 g/I Ni 16.9 g/j C1O, 04g/l Additive Glue 130g/electrolytic copper thiourea
95g/Electric steel cathode size 1025mLX 1025MW Anode size 990nmLX 970mW Number of cathodes
46 sheets/tank Number of anode sheets 47 sheets/slide electrolytic cell size 1200wmWX4850mLX 14
00mmH energization method Periodic reversal current method Table 2 Electrolysis result table of Example 1 <Example 2> 141 blister copper plate anodes as in Example 1 were sprayed with 150 kg/cII pressure water on the surface one by one. Washed. The washed blister copper anode was prepared under the three conditions shown in Example 1 and in Table 1 (
Electrolyze according to the electrolysis conditions table).

Example 1 of a blister copper plate anode whose surface is not washed at the same time
Comparative electrolysis was carried out in the same manner.

The electrolysis results are shown in Table 3 (electrolysis result table of Example 2). The electrical steels obtained were all 99.99% Cu, with no difference.

As can be seen from Table 3, the current efficiency of the cleaned anode according to the present invention is 1.0% compared to the conventional unwashed WS electrode.
It is improved by ~4.0%.

Table 3 Figure 1 shows the electrolysis results of Example 2, comparing the effect of anode cleaning with the case where only the perpendicularity of the electrode was improved and the case where a reversal current was periodically passed. This is an indication. As can be seen from this figure, by cleaning the anode, even if the current density is increased to a degree that could not be achieved with conventional measures, the problems that previously occurred with an increase in current density will not occur, and the current efficiency will be improved. can be maintained at a high level.

In addition, the anode cleaning area in the figure improves the perpendicularity of the electrode,
This is a case where a reversal current is periodically applied and the anode is further washed before electrolysis.

<Effects of the Invention> According to the method of the present invention, the blister copper plate anode is washed to remove copper oxides and foreign substances adhering to its surface before being used for copper electrolytic refining. Current efficiency can be improved by about 1-4%.

Expressing this in reverse, it is possible to increase the current density by the above proportion without reducing product quality and current efficiency, and also to shorten the distance between the electrodes, thereby improving the productivity of copper electrolytic refining. This means that you will be able to do so.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between current density and current efficiency in the case of cleaning the anode in comparison with other cases.

Claims (1)

[Claims] In a copper electrolytic refining method in which a blister copper plate is electrolytically refined in an acidic solution using a blister copper plate as an anode, the anode is washed in advance with an acidic solution or water to remove copper oxides and foreign matter adhering to the anode surface, and then electrolytically refined. An electrolytic refining method for copper, characterized in that it is used for.