JPS6230615A - Production of copper sulfate - Google Patents

Abstract

PURPOSE:To obtain high-purity copper sulfate inexpensively, by dissolving CuO powder obtained by electrolysis under a specific electrolytic condition in sulfuric acid and concentrating under heating and/or cooling it. CONSTITUTION:An anode using electrolytic copper and a cathode using a titanium plaste, copper plate, etc., are stored in permeable membrane bags made of a fiber such as PE, PP, polyester, etc., respectively, 0.3-1.1mol/l aqueous solution of Na2SO4 is adjusted to 5-13pH and 55-75 deg.C, electrolysis is carried out at 150-300A/m<2> cathode current density to form black CuO powder. Then, the CuO powder is optionally washed, dissolved in sulfuric acid, the solution is concentrated under heating and/or cooled, the formed crystallized substance is filtered and separated from the mother liquor and dried to give high-purity copper sulfate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing high-purity copper sulfate using electrolytic copper as a raw material.

[Conventional technology]

Copper sulfate, especially high-purity copper sulfate, is used for plating electronic component materials.

Conventionally, high-purity copper sulfate has been produced by dissolving electrolytic copper in sulfuric acid electrolytically or by heating to create a sulfuric acid W4 solution, and then heating and concentrating and/or cooling this solution, and removing the resulting crystallized product from the solution. It is manufactured industrially by methods such as filtering it from

[Problem that the invention seeks to solve]

However, with these methods, it is difficult to carry out electrolysis in such a way that the dissolved copper remains in the solution as much as possible without being electrodeposited on the cathode, and to increase the power consumption efficiency, resulting in high costs and melting heating. There was a problem in that the cost of steam and the cost of dissolving tank equipment increased.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a method that can produce high-purity copper sulfate at low cost.

[Means and effects for solving the problems] The method for producing copper sulfate according to the present invention does not involve directly preparing a copper sulfate solution using electrolytic copper as a raw material, but by first obtaining cupric oxide powder by an electrolytic method. We have discovered that the above objective can be achieved by subsequently dissolving this cupric oxide powder in sulfuric acid to create a copper sulfate solution, heating and concentrating and/or cooling this solution, and filtering it. be.

First, to obtain cupric oxide powder using electrolytic copper as a raw material,
□The method already proposed by the applicant in Japanese Patent Application No. 59-45563 is adopted. In this method, an electrolytic copper anode is used, and a copper plate, a titanium plate, etc. is used as the cathode. In order to achieve the purpose of the present invention, these anodes and cathodes must be housed in a diaphragm bag. It is. The diaphragm bag on the anode prevents slime generated from the anode from getting mixed in with the cupric oxide powder deposits produced, and prevents suspended matter in the electrolyte from adhering to the anode, and the diaphragm bag on the cathode prevents , preventing the hydrogen gas generated at the cathode from contacting the cupric oxide powder to reduce the powder and convert it into cuprous oxide and metallic copper. The diaphragm bag is made of polyethylene.

Made of fibers such as polypropylene and polyester,
It has a fine texture sufficient to achieve the above purpose. By using this diaphragm bag, the quality of cupric oxide formed in the electrolyte is significantly improved. In order to produce such high-purity cupric oxide powder, the concentration, pH,
Temperature and cathode current density need to be selected appropriately. The electrolyte concentration is 0.3 to 1 as N az SO4
．． The range is 1 mol/1. If it is less than 0.3 mol/1, the resistance of the electrolytic solution increases, resulting in large power loss and increasing the temperature of the electrolyte, which becomes complicated to maintain. Concentration is 1.1
If it exceeds mol/l, the viscosity of the electrolyte increases and the resulting cupric oxide powder becomes difficult to settle, and the increase in the concentration of suspended matter in the electrolyte increases the tendency for contact with hydrogen gas generated at the cathode. This will increase the reduced impurities and therefore the acid undissolved residue content in the recovered product.

The appropriate pH of the electrolytic solution is 5 to 13. If the pH is less than 5, the cupric oxide produced tends to dissolve and become Cu'' ions, and even if the pH exceeds 13, it tends to dissolve and form CuO,''- ions.

The temperature of the electrolyte ranges from 55°C to 75°C.

A certain degree of high temperature is required to decompose Cu(OH)t produced in the electrolyte, but too high a temperature has disadvantages such as increased energy consumption and the need for heat-resistant materials for electrolytic cells and other electrolytic equipment. I can't escape it.

The above objective can be fully achieved at a temperature of 75°C or lower.

However, at temperatures below 55° C., the recovered powder tends to contain 2% by weight or more of acid-undissolved residues other than cupric oxide.

Furthermore, the cathode current density is related to the production rate of cupric oxide powder, and in industrial scale implementation it is necessary to set it to 150 A/m" or more. However, if it exceeds 300 A/ml,
Hydrogen gas generation at the cathode increases, making it easier for suspended matter in the electrolyte to be reduced.

During electrolysis, the electrolytic solution is preferably stirred by means such as air blowing, and hydrogen reduction of the suspended matter is sufficiently prevented under the electrolytic conditions of the present invention.

In this manner, black cupric oxide powder is produced suspended in the electrolytic solution by electrolytic treatment. The powder is deposited at the bottom of the electrolytic cell, but is also suspended in the electrolyte and is recovered by filtering the electrolyte. By circulating the filtrate, the concentration of this suspension in the electrolyte can be increased to 20
It is preferable to maintain it below g/1.

Next, the recovered cupric oxide powder is washed if necessary and dissolved in sulfuric acid while being dried or undried. and,
In order to crystallize copper sulfate from the solution, the solution is heated and concentrated and/or cooled, which may be done by any conventional method. Finally, high purity copper sulfate is obtained by filtering and drying the crystallized product produced by heating and concentration and/or cooling from the mother liquor.

〔Example〕 Hereinafter, the present invention will be specifically explained with reference to Examples.

In the electrolytic tank, 1050 (vertical) x 1070 (horizontal) x 15
(thick) 21 pieces of electrolytic copper anodes and 10 pieces between them
20 cathodes of copper plates measuring 50' (length) x 1070 (width) x 4 (thickness) fi were inserted so that the distance between the electrodes was 130 mm, the anode and cathode were connected in parallel, and N a !
Electrolysis was carried out using an electrolytic solution with a S Oa concentration of 90 g/l (0.63 mol/l).During the electrolysis, the temperature was maintained at 65 °C and the pH at 10-12 while stirring the electrolysis method with air. (pH adjustment to 31i11 is carried out by adding solid sodium hydroxide).

Note that the current applied was a cathode current density of 267 A/mt,
A polyester cloth box (diaphragm bag) was attached to each of the anode and cathode. Then, spacers are placed on the cathode at intervals of about 100 * s in the lateral direction, so that the cathode and the box are in close contact with each other and the gas generated does not rise.
A vinyl chloride pipe of 0 mm diameter was placed across both sides of the cathode and hung vertically to its lower end. As a result of electrolysis for 72 hours, the anode current efficiency was 85 to 90%.

In addition, the suspended solids and electrolyte that have settled at the bottom of the electrolytic tank are filtered,
The cupric oxide powder obtained by drying was analyzed and a sulfuric acid solubility test was conducted. The analysis results of cupric oxide powder are shown in the following
Shown in the table.

Table 1 Sulfuric acid solubility test contains 5g 117) H2SO,
After weighing and adding 6 g of cupric oxide powder to the aqueous solution,
This aqueous solution was stirred and dissolved at 40°C for 1.2.3.4 and 5 minutes, and the respective dissolution rates were calibrated. As a result, the dissolution rates were 1.2.3° after 4 and 5 minutes. It was 69.97.99.99.99% by weight or more, respectively. ”
Commercially available cupric oxide powder (reagent-grade) under the same conditions as in 1.
As a result of conducting a sulfuric acid solubility test, the dissolution rate was 1.2.
At 5°10.20.30.40 and 50 minutes later, the amounts were 12.21, 36.43.55.64.68°72% by weight, respectively.

Next, 70% by weight of dilute sulfuric acid 1000e was added to the cupric oxide powder 2180k (moisture 60% by weight) obtained above, and then 60°C water 56001 was added. After filtering the solution to separate the solid content, the solution is heated to 90°C with water vapor.
The mixture was heated and concentrated for 2 hours.

The resulting solution was cooled to form a crystallized product. It was cooled to 25°C over 4 hours. Thereafter, the resulting crystallized product was filtered from the mother liquor and dried at 55°C.

The analysis results of the obtained copper sulfate crystals are shown in Table 2 below.

The copper sulfate crystals obtained in Table 2 had a high purity of 99% by weight or more.

〔Effect of the invention〕

As described above, according to the production method of the present invention, high purity copper sulfate can be produced at low cost.

Claims (1)

[Claims] Electrolytic copper was used as an anode, and the anode and cathode were each housed in a diaphragm bag, and the pH was 5 to 13, the temperature was 55 to 75°C, and the temperature was 0.3 to 1.
．． Electrolysis is carried out using a 1 mol/l aqueous sodium sulfate solution as an electrolytic solution at a cathode current density of 150 to 300 A/m^2, and then the cupric oxide powder produced is filtered from the electrolytic solution. A method for producing copper sulfate, which comprises dissolving dicopper powder in sulfuric acid, heating and concentrating and/or cooling the solution, and filtering the resulting crystallized product from the solution.