JPS6038997B2 - Ion exchange treatment method for cleaning wastewater from metal surface treatment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for ion exchange treatment of cleaning wastewater for metal surface treatment.

Specifically, wastewater from cleaning plated surfaces such as copper plating, nickel plating, or zinc plating, or wastewater from cleaning steel surfaces after pickling, which does not contain sodium hydroxide or potassium, is used as an ion exchange resin. The present invention relates to a method of obtaining pure water by contacting with water. Traditionally, the main method for treating cleaning wastewater for metal surface treatment has been neutralization coagulation and sedimentation, but this method had the disadvantage that the treated water contained a large amount of salts and could not be reused, and there were problems with the treatment and disposal of sludge. .

In addition, due to resource shortages and rising prices, in recent years treatment with ionic resin has been widely used to recover valuable metals from wastewater, obtain pure water, and reuse both. came to be used.
Ion exchange of cleaning wastewater for metal surface treatment ≠ In treatment with sword resin, suspended solids in the wastewater are first removed in a furnace filter, valuable metal ions are adsorbed in a strongly acidic cation exchange resin column, and finally sulfate ions are removed. This is a method to obtain pure water by adsorbing anions such as the following in a strongly basic or weakly basic anion resin tower.

In this method, when cations other than hydrogen ions begin to leak from the strongly acidic cation exchange resin tower (this is called a cation break), the pH increases and metal hydroxides precipitate in the anion exchange tower. The deposited hydroxide precipitate cannot be dissolved and removed by the alkali regeneration of the anion exchange tower, which has the disadvantage of reducing the anion exchange capacity of the anion exchange tower.

For this reason, conventionally, approximately 80% of the total amount of wastewater treated (estimated amount of treated water) corresponding to the total exchange capacity was passed through (this is called constant volume operation), and then the regeneration process was started for safety reasons. As a result, the entire ion-exchange resin is not effectively utilized, and as a result, the equipment becomes larger and the water flow time becomes shorter. The present invention utilizes the total exchange capacity of the ion exchanger column to the maximum extent, making the equipment more compact than conventional methods, and making it possible to extend the water flow time for cleaning waste water from metal surface treatment. The object of the present invention is to provide an ion exchange treatment method.

The present invention provides cleaning wastewater for metal surface treatment (hereinafter referred to as raw water) that contains only cations that form hydroxide precipitates in an alkaline atmosphere in addition to hydrogen ions.
is brought into contact with a cation exchange resin and then with an anion exchange resin to obtain treated water, in which a leakage detection cation that does not produce hydroxide precipitation in an alkaline atmosphere is added to the waste water, This is an ion exchange treatment method for cleaning wastewater for metal surface treatment, characterized in that when leakage of the leak detection cation is detected in the treated water, cation exchange≠sword resin is regenerated. Examples of raw water include cleaning wastewater discharged when copper-plated, nickel-plated, or zinc-plated surfaces are washed with pure water, and wastewater from cleaning steel surfaces with pure water after pickling. but,
It is not limited to this. The ions in raw water vary depending on the type of plating solution, but for example, cations include hydrogen ions, copper ions, nickel ions, or zinc ions, and anions include sulfate ions, chloride ions, nitrate ions, or phosphate ions. Generally, it does not contain sodium ions or potassium ions, and even if it does, it is in such a trace amount that it can be virtually ignored. As the cation exchange resin, an acidic cation exchange resin is used. A weakly acidic cation exchange resin cannot be used unless it is in an alkaline atmosphere because it does not have an ion exchange key. The anion exchange resin may be either a strongly basic anion exchange resin or a weakly basic anion exchange resin since the acidic water that has been subjected to the cation exchange treatment in the previous stage flows into the anion exchange resin. It may be used as a multi-layer structure in which the upstream side is filled with a weakly basic anion exchange resin and the downstream side is filled with a strongly basic anion exchange resin. The cation exchange resin is regenerated into the H form, and the anion exchange resin is used in the O form.
Regenerate into H-form and use. The ion-exchangeable resin is usually used by filling a column, but in the present invention, the direction of water flow through the column may be either an upward flow or a downward flow. Cations for leak detection are
Examples include sodium ions, potassium ions, and ammonium ions, but since ammonium ions form rust bodies together with copper ions, it is usually preferable to use sodium ions or potassium ions.Additional forms include sodium chloride, potassium chloride, and sodium sulfate. can be added as an aqueous solution.

The additive concentration may be sufficient as long as it is sufficient to detect cation break, and is usually 2% to 20% of the cation concentration of the raw water.
% is the standard.

If it is less than 2%, cation break is detected and the
Moreover, if it exceeds 20%, the load on the ion exchange resin becomes high, and the ion exchange capacity available for recovering valuable metals becomes small.

The addition location may be anywhere in front of the cation column filled with cation exchange resin; for example, it may be added to the raw water storage tank in advance, or it may be injected into the piping in front of the cation exchange resin column during ion exchange treatment. Good too. Further, as for the timing of addition, as mentioned above, it may be added to the raw water in advance, or it may be added during the water flow, especially after the conventional regular operation has been performed. In this way, when ion exchange treatment is performed by adding cations for leak detection, such as sodium ions, to raw water, sodium ions are more active than cations that produce hydroxide precipitates in an alkaline atmosphere, such as copper ions, nickel ions, and zinc ions. Due to its weak selectivity, it leaks first from the cation tower and passes through the anion tower filled with anionoisotropic resin, so it eventually leaks into the treated water in the form of sodium hydroxide.

This leakage can be detected by measuring electrical conductivity and spots, and can also be known by immediately measuring the sodium ion concentration using an ion electrode. For handling and other reasons, it is preferable to use an electrical conductivity meter. If leakage detection cations are detected in the treated water,
The cation tower performs regeneration. For regeneration, add hydrochloric acid or sulfuric acid to 1
Valuable metals can be recovered by making an aqueous solution of about 35% and passing it through the water. If the exchange capacity of the anion tower is set so that it breaks almost simultaneously with the break of the cation tower, regeneration with alkali is performed at the same time. As the alkali, sodium hydroxide, ammonia, coal, etc. can be used, but sodium hydroxide is preferred. According to the present invention, since the cation break can be detected, the anion exchange resin is not contaminated with metal hydroxide precipitation, and the total exchange capacity of the ion exchange resin can be utilized to the maximum extent possible. , the device can be made smaller or the water flow time can be made longer than the conventional method.

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

Example 1 A cation tower filled with 800 ml of a strongly acidic cation exchange resin, Revatit (trademark of Bayer) S-100, and an anion column filled with 7,000 ml of a weakly basic anion exchange resin, Levacit M-64, were prepared in this order. Copper glaze cleaning wastewater (
CuS04409/so, H intersection 042000c/so,
) was passed through with an upward flow of 10〆/hr, and when the electrical conductivity of the treated water reached 5 fs/skin, the water flow was stopped, and after regeneration, the water flow was repeated.

At that time, the weakly basic anion exchange resin MP-64 was analyzed after 20 cycles of operation for cases A in which 1 volume/kg of sodium chloride was added to the raw water and B in cases in which no sodium chloride was added, as shown in Table 1. there were. Table 1 From Table 1, it can be seen that when sodium chloride is added to the raw water, the result is the same as that of a new resin, whereas when no sodium chloride is added, the exchange capacity decreases and copper is deposited.

Example 2 Strongly acidic cation exchange resin Revacit S-100 at 170%
A cation column filled with 8000 g of the weakly basic anion exchange resin Revacit MP-64 and an anion column filled with 8000 g of the weakly basic anion exchange resin Revacit MP-64 were treated in this order with 5 parts and 9 parts of sodium chloride added to the copper glaze cleaning waste water ( CuS0480-130 9/So, Sun 2S04400-600m9/So) 25〆/hr
Water was passed in an upward flow, and when the electrical conductivity of the treated water reached 20 French s/skin, the water flow was stopped, and the water flow was repeated after the water was discharged again.

Claims (1)

[Scope of Claims] 1. Contacting cleaning wastewater from metal surface treatment, which contains only cations other than hydrogen ions that produce hydroxide precipitates in an alkaline atmosphere, with a cation exchange resin,
In the ion exchange treatment method in which treated water is then obtained by contacting with an anion exchange resin, a leakage detection cation that does not produce hydroxide precipitation in an alkaline atmosphere is added to the wastewater, and leakage of the leakage detection cation into the treated water is performed. A method for ion exchange treatment of cleaning wastewater for metal surface treatment, characterized in that the cation exchange resin is regenerated when the cation exchange resin is recognized. 2. The ion exchange treatment method according to claim 1, wherein the leak detection cation is a sodium or potassium ion.