JP3163612B2 - Copper removal electrolysis from chloride bath - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing copper from a chloride bath by which a nickel mat is leached with chlorine and high-purity electric nickel can be produced with high current efficiency from the obtained leachate. It is.

[0002]

2. Description of the Related Art Conventionally, as a method for obtaining electric nickel from a nickel mat, a nickel mat is suspended in a solution containing copper and nickel and valuable metals in the nickel mat are leached by blowing chlorine. There is a method of electrowinning nickel from the leachate. in this way,
Because of the concentration of copper in the leachate, some form of copper must be removed out of the system. As one of the methods,
There is a copper removal electrolytic method. This copper-free electrolytic method means, for example, that an anode obtained by coating a surface of a titanium plate or net with a noble metal oxide is placed in a box, a titanium plate or a stainless steel plate is used as a cathode, and a copper Is precipitated as copper powder.

[0003]

However, in this operating method of copper removal electrolysis, the electrolytic solution supplied to the copper removal electrolytic process is supplied without adjustment, so that the nickel concentration in the electrolytic solution, the copper concentration, Since the concentration, pH and the like are determined depending on the situation, a good operating state is not always maintained. That is, when the copper concentration in the electrolytic solution is 40
When the amount is more than g / liter, the amount of Cu ²⁺ increases in the copper-free electrolytic system, which causes a disproportionation reaction with the copper powder generated on the cathode side, Cu ⁰ + Cu ²⁺ = 2Cu ⁺ , and re-dissolves the copper powder. As a result, there is a problem that the cathode current efficiency is reduced.

When the concentration of nickel or copper in the supplied electrolytic solution increases, the viscosity of the electrolytic solution increases, and the filter cloth used for the anode becomes clogged, thereby increasing the electrolytic voltage. This increase in the electrolytic voltage raises the temperature of the electrolytic solution to 80 ° C. or more, and causes problems such as deformation of the vinyl chloride anode box, reduction in the life of the filter cloth, and peeling of the coating material on the anode surface.

The present invention solves the drawbacks of lowering the cathode current efficiency, increasing the electrolysis voltage, and increasing the temperature in the electrolytic cell, and provides a method for stably removing excess copper as copper powder at low cost. It is intended to provide.

[0006]

Means for Solving the Problems The inventors of the present invention have repeatedly studied to solve the above-mentioned problems and achieve the above-mentioned object, and as a result, the nickel concentration, the copper concentration, the pH, etc. in the electrolytic solution have been set to specific ranges, respectively. As a result, the present inventors have found that the object can be achieved, and have completed the present invention. That is, the present invention provides a chloride solution obtained by suspending a nickel mat containing copper in a solution containing copper and nickel, and blowing chlorine to leaching valuable metals such as nickel and copper. In the method of electrolytically collecting copper, the nickel concentration of the electrolytic solution supplied to the electrolytic cell is 100 to 180 g / liter, the copper concentration is 30 to 40 g / liter, and the pH is 0 to 0.
2. A method of removing copper from a chloride solution by using a nickel chloride solution, a hydrochloric acid solution and / or water to adjust the electrolytic solution. It is.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the method of the present invention, the nickel concentration of the electrolytic solution supplied to the electrolytic cell is limited to 100 to 180 g / liter. When the nickel concentration is higher than this range, nickel becomes nickel chloride. In addition, calcium in the electrolytic solution comes to precipitate as gypsum. The sulfate group as the gypsum source is generated by oxidizing sulfur when the nickel mat is leached with chlorine. When the salt or gypsum precipitates in this way, the pipes may be blocked, or the diaphragm of the anode box may be clogged. In other words, if the piping is blocked, the operation must be stopped, and if the diaphragm of the anode box is clogged, the diaphragm resistance increases, the electrolytic voltage increases, and the same adverse effects caused by the increase in the electrolytic solution temperature as in the past occur. appear. Furthermore, if the nickel concentration is lower than this range, the water balance cannot be maintained in the next step, for example, the nickel electrowinning step, and the electrolyte must be discharged out of the system as a waste liquid, which increases the production cost. Because it becomes.

When the copper concentration exceeds 40 g / liter,
The amount of divalent copper ions in the electrolytic cell increases too much, and the metallic copper produced at the cathode is redissolved by the disproportionation reaction, resulting in a decrease in current efficiency. On the other hand, when the copper concentration is less than 30 g / liter, Then, nickel began to electrodeposit on the cathode,
This is because the nickel content in the copper powder discharged to the outside of the system increases, and the loss of nickel increases. Therefore, the copper concentration of the electrolytic solution supplied to the electrolytic cell needs to be in the above range.

Further, when the pH of the electrolytic solution is too high, the amount of nickel deposited on the cathode increases, and the efficiency of recovering copper decreases, so that the loss of nickel increases. In this method, iron in the electrolytic solution precipitates as hydroxide, and the diaphragm of the anode box is blocked, so that the electrolytic voltage increases. Conversely, if the pH is too low, the metal copper deposited at the cathode will be chemically dissolved and the electrolysis efficiency will be reduced. When the pH is less than 0,
The service life of the coating on the anode box diaphragm and anode surface is significantly reduced. Therefore, the pH is set to 0 to 2.0.

[0010] However, in order to obtain such ranges, adjustment is performed using at least one of a nickel chloride solution, a hydrochloric acid solution and water.

[0011]

Next, an embodiment of the present invention will be described.

Example 1: Before the concentration adjustment, the composition of the electrolytic solution for removing copper was Ni 200 g / l, Cu 60 g / l (C
u ²⁺ /TCu=0.5) with nickel chloride (Ni
(60 g / L, Cu <0.1 g / L) The electrolytic solution was supplied by adjusting the copper concentration as shown in the section of Example 1 in Table 1 below. The electrolysis was carried out at a current of 610 A / cathode at a supply rate of 60 ml / A · H. From the obtained results, the cathode current efficiency was calculated using the following equation 1. Table 1 shows the results.

[0013]

[Formula 1] Cathode current efficiency (%) = (Copper powder produced x Copper grade (%) / (Cu2 ⁺ electrochemical equivalent x Energizing time x Energizing current)

[0014]

[Table 1]

Comparative Example 1: The copper concentration was adjusted in the same manner as in Example 1 as shown in the section of Comparative Example 1 in Table 1 to obtain an electrolytic solution, and the operation was performed in the same manner as in Example 1. Are shown in Table 1. From the results shown in Table 1, the copper concentration was 30 to 40 g.
It can be seen that good results were obtained in the case of the range of / l.

Example 2 The nickel concentration was kept constant at 180 g / liter, and the copper concentration (Cu ²⁺ /TCu=0.5) was adjusted as shown in the section of Example 2 in Table 2 below to obtain an electrolytic solution. The temperature of the electrolytic solution supplied to the electrolytic cell is 50 to 5
The same operation as in Example 1 was carried out except that the temperature was changed to 2 ° C., and the obtained results are shown in Table 2.

[0017]

[Table 2]

Comparative Example 2: As in Example 2, the nickel concentration was kept constant at 180 g / liter and the copper concentration (Cu ²⁺ / T
(Cu = 0.5) was adjusted as shown in the section of Comparative Example 2 in Table 2 to obtain an electrolytic solution. The electrolysis conditions were operated in the same manner as in Example 2, and the obtained results are shown in Table 2. From the results shown in Table 2, it can be seen that good current efficiency can be obtained when the copper concentration is in the range of 30 to 40 g / liter, and that the temperature in the bath does not increase so much.

Example 3 Copper concentration (Cu ²⁺ / TCu =
0.5) was fixed at 35 g / liter, and the nickel concentration was adjusted as shown in the section of Example 3 in Table 3 below to obtain an electrolytic solution. The electrolytic conditions were the same as in Example 2, and the same as in Example 1. Table 3 shows the obtained results.

Comparative Example 3: Copper concentration (Cu ²⁺ / TCu =
0.5) was fixed at 35 g / liter, and the nickel concentration was adjusted as shown in the section of Comparative Example 3 in Table 3 to obtain an electrolytic solution. The electrolytic conditions were the same as in Example 2, and the operation was the same as in Example 1. Table 3 shows the obtained results.

[0021]

[Table 3]

From the results in Table 3, it can be seen that good current efficiency was obtained when the nickel concentration was within the range of the present invention. In addition, in the case of 200 g / liter, the current efficiency of divalent copper ions is reduced, nickel deposition is recognized, and the electrolytic cell voltage and the temperature in the cell are also increased. Note that 80
Although the current efficiency is good even at g / liter, the water balance as a whole of the nickel recovery is lost, and the electrolyte must be discharged out of the system, so that the nickel production cost becomes high. Not fit.

EXAMPLE 4 The nickel concentration was 180 g / l and the copper concentration (Cu ²⁺ /TCu=0.5) was 35
g / liter, and the pH was changed as shown in Example 4 in Table 4 below, the electrolysis conditions were the same as in Example 2, and the operation was the same as in Example 1, to obtain the obtained copper powder. We asked for nickel grades. Table 4 shows the results.

Comparative Example 4: The same operation as in Example 4 was carried out except that the pH was changed to 2.2, and the obtained results are also shown in Table 4.

[0025]

[Table 4] From the results in Table 4, it can be seen that when the pH exceeds 2, the nickel quality in the copper powder sharply increases, and the loss of nickel increases.

[0026]

According to the present invention, nickel concentration, copper concentration, pH
Since the electrolytic operation was performed with a specific range such as
A remarkable effect is observed such that voltage rise due to clogging of the diaphragm of the anode box, associated rise in liquid temperature, clogging of pipes, etc. can be prevented, and copper-free electrolytic operation can be maintained with high current efficiency.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Susumu Makino 3-5-3 Nishiharacho, Niihama-city, Ehime Prefecture Sumitomo Metal Mining Besshi Works Nickel Works (56) References JP-A-5-295467 (JP, A (58) Fields surveyed (Int. Cl. ⁷ , DB name) C25C 1/00-7/08

Claims (2)

(57) [Claims] 1. A copper-containing nickel matte is suspended in a solution containing copper and nickel, and chlorine is blown in to leaching valuable metals, and copper is electrolytically collected using a chloride solution obtained as an electrolytic solution. In the method, the electrolytic solution supplied to the electrolytic cell has a nickel concentration of 100 to 180 g / liter, a copper concentration of 30 to 40 g / liter, and a pH of 0 to 2.0. Copper removal electrolytic method. 2. A nickel chloride solution for adjusting the electrolytic solution,
2. The method for removing copper from a chloride solution according to claim 1, wherein at least one of a hydrochloric acid solution and water is used.