JPS5943983B2 - Method for selectively removing cobalt ions in zinc leachate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for selectively removing cobalt ions in zinc leachate.

In order to extract high-grade electrolytic zinc from the leachate in hydrometallurgical zinc smelting, a liquid purification process is required to remove impurities, especially impurities that have a harmful effect during the electrolytic process.

If impurities with low hydrogen overvoltage are present in the electrolyte, they will not only precipitate and reduce the purity of zinc products, but also prevent the precipitation of zinc itself, significantly reducing the current effect, and ultimately reducing product costs. It causes an increase.

In some cases, severe re-dissolution of precipitated zinc occurs, which can be devastating to operations.

These are described in Hydrometallurgical Refining Technology P21 (Japan Mining Industry Hydrometallurgical Technology Research Committee complete edition, Nichia Shobo).

For this reason, many studies have been made regarding methods for removing these impurities.

Impurities contained in the electrolyte include magnesium, copper,
These include manganese, cadmium, iron, cobalt, nickel, and others. To remove harmful copper and cadmium, a metal substitution reduction method using zinc powder is used, and depending on the type of ore, it is combined with a precipitation adsorption method during roasting and leaching. At present, a multi-stage liquid purification process with various ingenuity is being used.

However, the most problematic cobalt is cobalt, which is contained in the leachate from several ppm to several + ppm, but even a very small amount causes the above-mentioned problems during electrolysis, so it is considered that there is no problem. , 31) I) Efforts are being made to lower it to below III.

There are two types of cobalt removal methods:

■) A method in which arsenous acid and zinc powder are added in the presence of copper ions to lower the potential of the zinc powder and cobalt is precipitated by displacement.

2) A method of forming a chelate compound insoluble with cobalt using α-nitroso-β-naphthol.

However, the former consumes a large amount of zinc powder and has the problem of generating arsine gas due to arsenic, which is a life-threatening problem for workers.On the other hand, in the latter, α-nitrone-β-naphthol is expensive, so it cannot be used in the system. A method has been adopted in which α-nitroso-β-naphthol is synthesized by adding β-naphtate and sodium nitrite, but this naturally requires an excessive amount of chemicals to sufficiently remove cobalt, and furthermore, this is caused by electrodeposition. Since it is harmful to the environment, measures such as removing the excess with activated carbon are required.

The present inventors investigated a new method for removing cobalt from this perspective, and found that the orthonitrone phenol analog introduced into the sulfonic acid group and cobalt were brought into contact with cobalt in an aqueous solution system to form a complex. When this complex was treated with a basic ion exchange resin, it was discovered that the objective could be achieved in a shorter time and with a smaller amount than the corresponding nitrosophenol, and the present invention was achieved based on this finding.

That is, the present invention is based on the general formula (1) [wherein R is a C6 to C1□ (n+2)-valent aromatic group,
The OH group and the No group are directly connected to the aromatic nucleus and are arranged ortho to each other, M represents hydrogen or an alkali metal, and n represents an integer of 1 to 3.

] The zinc sinter leachate is treated with a water-soluble nitrone compound shown in the following formula to form a complex between the water-soluble nitrone compound and cobalt ions in the zinc sinter leachate, and the formed complex is converted into a basic ion. This is a method for selectively removing cobalt ions in a zinc leachate, which is characterized by adsorption and removal using an exchange resin.

The water-soluble nitrone compound referred to in the present invention is the general formula (I
), in which a hydroxyl group and a nitroso group are arranged ortho to each other on the aromatic nucleus, and at least one sulfonic acid group.

Specific examples include the following compounds CI) to [X] or their salts such as sodium and potassium.

Among these, the most useful water-soluble nitroso compound is [I]■
-Nitroso-2-oxy 3,6-naphthalene disulfonic acid, (n) 1-nitrone-2-oxy-6-naphthalene sulfone e, CI[) 1-nitrone-2-oxy-7
-naphthalenesulfonic acid, [V]2-nitroso-1-oxy-4-naphthalenesulfonic acid, (4)]2-nitron-1-oxy-5-naphthalenesulfone.

These water-soluble nitroso compounds may be in the form of an acid or a salt such as sodium or potassium, and can be used as appropriate depending on stability and synthesis conditions, but generally (
V) (Since the alkali metal salt of the compound Wl is unstable, it is preferable to use the compound in the form of a free acid and the other compounds in the form of a salt such as sodium or potassium.

However, the hydroxyl and nitroso groups must be ortho to each other.

This is because cobalt forms a stable 5- or 6-membered ring chelate structure with these groups.

The water-soluble nitrone compound used in the present invention can be obtained by reacting the corresponding aromatic oxysulfonic acid with nitrite in an acidic solvent.

In the method of the invention it is first necessary to form a complex.

For this purpose, as in the nitrosonaphthol method, a water-soluble nitroso compound is added to the purified solution after decadmium removal, but since the nitroso compound used in the present invention is water-soluble, the chelate formation rate is extremely fast at pH 5 to 7 at room temperature. However, since it can be completed within a few minutes, it greatly contributes to shortening the process.

The optimum pH to be applied is within the above range, but pH 2 to 8
, more preferably pH 3-7.

Although room temperature is sufficient, the chelation rate can be accelerated by increasing the temperature to a higher temperature.

Nitrosonaphthol and cobalt are CoCC, oHO(N
It is said that a strongly acidic, reddish brown, trivalent, stable complex represented by 1.
2 to 2.5 times the molar amount is sufficient, and one of the major features of the present invention is that it can be processed with such a small amount.

This is presumed to be related to the fact that the chelate-forming group easily comes into contact with cobalt ions in an aqueous solution.

This formed complex of cobalt and a nitroso compound is water-soluble in most cases, and since this does not solve the problem of subsequent electrodeposition, next, in the present invention, it is made into a basic solution. It is necessary to adsorb and remove with an ion exchange resin.

Even in the case of nitrosonaphthol, it is necessary to adsorb unreacted chemicals with activated carbon, so this does not lead to an increase in the number of steps.

The basic ion exchange resin used in the present invention may be of any type, but a strongly basic type is particularly effective because it has a high rate of adsorption of water-soluble nitroso compounds and cobalt complexes.

This indicates that the sulfonate group of the nitroso compound forms a salt-forming bond with the ion exchange resin through ion exchange.

The conditions for treatment with a basic ion exchange resin in the present invention are preferably at a temperature of 40 to 80°C, particularly 50 to 70°C.

The pH should be 7 or higher, and a lower pH is preferable because the adsorption rate of the cobalt complex is faster and the amount of basic ion exchange resin used can be reduced, but there are problems with the stability of the resin and the acid resistance of the offshore wood. For this reason, it is not desirable to set it too low.

It is usually preferable to carry out the treatment at pH 3 to 7, particularly pH 3 to 5.

It is sufficient that the amount of basic ion exchange resin used is 1.1 to 1.5 times the volume calculated from its exchange capacity, and the pH
3-5, the most common method is to process at a temperature of 50-70°C for about 10-30 minutes.

In the present invention, it is also possible to add a nitrone compound and a basic ion exchange resin to the system at the same time.

In this case, the pH and temperature conditions can be as described above.

According to the present invention, the concentration of cobalt can be reduced from 0 to 3 p using a small amount of water-soluble nitroso compound in a shorter time than conventional methods.
It can be removed down to pm or less.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 1-Ninaroso 2-oxy-3,6-naphthalene disulfonic acid disodium salt and Toroso R salt were added to 500 ml of zinc sinter leachate after decadmium removal.12.
8 Y (1.3 times the theoretical amount) to dissolve and adjust the pH to 4.
After stirring at 50°C for 15 minutes, 0.4 ml of a strongly basic anion exchange resin (Diaion 5AIOA (J' type exchange capacity 1.3 meq, 7 ml or more, manufactured by Mitsubishi FH) was added, and the mixture was stirred again for 15 minutes. After that, C in P solution.

Concentrations were measured by atomic absorption spectrometry.

As a result, the Co concentration was 0.2pI)Ill.

On the other hand, nitroso-β-naphthol was treated in the same manner as the nitroso R salt using the same mole.

As a result, the Co concentration was 1.11)I)m.

As is clear from this result, the method of the present invention can reduce C in a short time.
o concentration can be 0.2 pI) III.

Example 2 20 g of β-naphthol was heated to 100-110° C. in 40 g of fuming sulfuric acid for about 10 hours.

After cooling, the solution was neutralized with caustic soda, 200 ml of concentrated hydrochloric acid was added, and the solution was cooled to 8-9°C.

Next, a solution containing 144 g of sodium nitrite was added over 30 minutes with stirring, and the reaction was continued again at this temperature for 1 hour.
Washed twice and dried.

The obtained nitroso compound is yellow-green, easily water soluble, has a nitrogen analysis value of 4.2%, and contains 1 of α-nitroso-β-naphthol.
It is estimated that the main component is a mixture of ~3 polyvalent sulfonates.

This compound 127In9 (1.5 times the theoretical amount by mole) was added to 500 ml of the leachate of Example 1, and after stirring at pH 4 and 55°C for 15 minutes, the pH was adjusted to 2 with sulfuric acid and a strongly basic anion exchange resin (ROHM Manufactured by Andverse, Amberlite I RA-400 (J' type exchange capacity 1.4meq 7m
1) After adding 1.0 ml and stirring again for 15 minutes, the Co concentration was measured in the same manner as in Example 1.

As a result, the Co concentration was 0.3.

Example 3 2-Nitroso-1-oxy-naphthalene-4 = sulfonic acid 116~ (1.8 times the theoretical equivalent) and a strongly basic ion exchange resin (Dow Chemical Co., Ltd. DOWEX 1 = X4
(J' type exchange capacity 1.2meq/m1) 1.0rn
l to 500ml of the leachate from Example 1, and the pH was adjusted with sulfuric acid.
4, stirred at 60°C for 30 minutes, and prepared in the same manner as in Example 1.
o concentration was measured.

As a result, the Co concentration was 0.31)I)m.

Example 4 7.0 g of P-phenolsulfonic acid was nitrosated from 40 g of fuming sulfuric acid in the same manner as in Example 2, neutralized with caustic soda, and then concentrated to dryness under reduced pressure.

The product is green in color, readily water soluble and has a nitrogen analysis of 5.4%;
Sodium O-nitroso-P-phenolsulfonate containing inorganic salts is believed to be the main component.

This compound 112'In9) (1.7 times the theoretical amount in mole) was used in the same manner as in Example 3, and the Co concentration was measured.

As a result, the concentration of Co was 0.21)I)III.

Claims (1)

[Claims] 1 General formula (1) [However, R is a C6 to C12 (n+2)-valent aromatic group,
The OH group and the NO group are directly connected to the aromatic nucleus and are arranged ortho to each other, M represents hydrogen or an alkali metal, and n represents an integer of 1 to 3. ] The zinc sinter leachate is treated with a water-soluble nitroso compound shown in the formula to form a complex between the water-soluble nitroso compound and cobalt ions in the zinc sinter leachate, and the formed complex is treated with a basic ion exchange resin. A method for selectively removing cobalt ions in a zinc leachate, the method comprising adsorbing and removing cobalt ions using a zinc leachate. 2. The method according to claim 1, wherein the water-soluble nitroso compound is 1-nitroso-2-oxy-3,6-naphthalene disulfonic acid disodium salt and Toroso R salt. 3. The method according to claim 1, wherein the water-soluble nitroso compound is 1-nitroso-2-oxy-6-naphthalenesulfonic acid sodium salt. 4. The method according to claim 1, wherein the water-soluble nitroso compound is 1-nitrone-2-oxy-7-naphthalenesulfonic acid sodium salt. 5. Claim 1, wherein the water-soluble nitrone compound is 2-nitroso-1-koxy-4-naphthalenesulfonic acid.
The method described in section. 6 Claim 1 in which the water-soluble nitroso compound is 2-nitroso-1-oxy-5-naphthalenesulfonic acid
The method described in section. 7. The method according to any one of claims 1 to 6, wherein the basic ion exchange resin is a strongly basic ion exchange resin in the form of a quaternary ammonium salt.