JPS62280375A - Device for water-washing chemical-conversion treated article - Google Patents

Abstract

PURPOSE:To highly enhance the purity of treated washing water with the title comparatively convenient device by passing the washing water through a set of a cation- and an anion-exchange tower until the electrical conductivity is adjusted to less than a specified value, and then returning the water to a washing vessel in the closed-system washing device. CONSTITUTION:An article, for example, is plated in a plating bath 1, and successively sent in the direction as shown by the arrow. The deposited plating soln. is recovered in a recovery tank 2, and the article is washed with water in washing vessel 3 and 4. Fresh washing water is replenished to the vessel 4 from a tank 6, and overflows into the vessel 3. The spent washing water from the vessel 3 is filtered by a filter F, introduced into a looped circuit 10 through a valve V1, and passed through the cation-exchange tower K and the anion-exchange tower A. The electrical conductivity of the water after passing through the towers is monitored by a meter M at all times. When the value of the conductivity is lower than the set value, e.g., <=0.5muS/cm, a valve V2 is closed, a valve V3 is opened, and the device is operated. When the conductivity exceeds the set value, the valves V1 and V3 are closed, the valve V2 is opened, and washing water is circulated through the circuit 10 to control the conductivity to lower than the set value.

Description

[Detailed description of the invention] 3. Detailed description of the invention! BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a washing apparatus for chemically treated articles, and more particularly to such a washing apparatus that employs a closed system in which used washing water is purified and reused.

In chemical conversion treatment of articles, such as plating treatment, washing with water is required to wash away adhering chemicals.

Although the water used for this washing is diluted, it contains harmful substances such as chromium and cyanide, so it cannot be released directly into the environment. Moreover, since the washing water is dilute, it is produced in a large amount, requiring a large amount of F9 in wastewater treatment equipment, and the operating cost thereof is also relatively high, requiring concentration treatment.

Therefore, a closed system that purifies and reuses the washing water itself and does not release wastewater to the outside is ideal. Conventionally, devices are known in which used washing water is sequentially passed through a filter, a cation exchange tower, and an anion exchange tower to remove water-insoluble impurities and contaminant ions before being returned to the washing tank. This requires the combined use of an expensive mixed bed type ion exchange tower. The purity of the water that is returned after being treated with deionization using only a multi-bed system with low recycling costs is 10μ in terms of conductivity.
The limit was about S/cm.

Therefore, the present invention aims to provide a relatively simple device that can purify washing water to a higher level of purity, for example, to a conductivity of about 0.5 μS/cm, and return it to the washing tank. Take it as a challenge.

The present invention is a closed-type washing device in which chemically treated articles are washed in a washing tank, and the used washing water is purified and then returned to the washing tank. A cation exchange tower and an anion exchange tower are provided, and the used washing water from the washing tank is purified through the set of ion exchange towers and then circulated to the washing tank, and further downstream of the set of ion exchange towers and the ion exchange tower. A loop circuit is provided to connect the upstream of the tower, and when the conductivity of the wash water after passing through the set of ion exchange towers is above a predetermined value, the wash water is continued until the conductivity falls below the predetermined value. The loop circuit is circulated, and when the conductivity of the washing water after passing through the set of ion exchange towers is less than a predetermined value, the loop circuit is closed and the washing water that has passed through the ion exchange towers is washed with water. The present invention relates to a water washing device for chemical conversion treated articles, characterized in that it is equipped with means for controlling the flow of washing water so as to return it to a tank.

Preferably, the used wash water is filtered through a gravity fiber filter before being introduced into the ion exchange column.

The first mouth The drawing is a schematic diagram of a specific example of the device of the present invention.

Taking chrome plating as an example of a chemical conversion treatment, articles are plated in a plating tank 1, are sequentially sent in the direction of the arrow, and the adhering meso+ liquid is collected in a recovery tank 2, and then transferred to a first washing tank 3. It is washed with water in the second water washing jW4. The second washing tank 4 is replenished with fresh washing water from a tank 6, which overflows and is sent to the first washing tank 3. In these washing tanks, the articles are therefore washed countercurrently with fresh washing water.

In this example, the used washing water from the first washing tank 3 is introduced into a loop circuit generally indicated by 10, after water insoluble matter is removed in a filter F, either directly or once through the tank. It has become.

Filter F is preferably a gravity flow type fiber filter, particularly a filter using spherical fiber aggregates as a filter medium. This type of filter is advantageous because water-insoluble suspensions are deposited on the fiber surface and fine particles are better captured. Furthermore, by backwashing this filter, deposited particles easily fall off and are discharged as a concentrated liquid, making maintenance easy.

The cleaning water that has passed through the filter F is introduced into the loop circuit through the valve 1. Normally, valve (1) is in the open position, valve (3) is in the open position, and valve (2) is in the closed position. The conductivity of the water that has passed through the cation exchange tower K and the anion exchange tower A is constantly monitored by a meter M installed downstream of the ion exchange tower. If the value of this conductivity is less than a predetermined value, for example 0.5 μS/0 m, the device is operated in this state. However, due to a short circuit occurring inside the ion exchange tower, sufficient deionization was not achieved, and the meter M did not reach the predetermined value, for example, 0.5 μs/cm.
When a higher conductivity is detected, a signal is sent to the controller, and the controller closes valves (1) and (3) and opens (2) to circulate cleaning water within the loop circuit 10. This will repair the short circuit that occurred inside the ion exchange tower.
Water with conductivity below a predetermined value can be obtained. Therefore, in response to the low conductivity below a predetermined value sensed by the meter M, the controller generates a signal to open valves ■1 and ■3 and close valve ■2, allowing the cleaning water that has passed through the ion exchange tower to is sent to the tank 6 upstream of the washing tank 3.4, and at the same time, while the washing water is circulating in the loop circuit 10, the used washing water stored in the tank 5 passes through the filter F and undergoes ion exchange. Introduction to the pair of towers is resumed.

Generally, in ion exchange treatment, if the liquid passing rate is too high, a short circuit will occur within the column and the treatment will be incomplete, so for safety reasons, the liquid passing rate is usually set to a low value. Therefore, it was necessary to update the device with the ion exchanger still active, but even if a short circuit occurs in the device of the present invention, it can be repaired in a short time as described above, so this could not be used in the past. Good deionization is now possible even when water is passed through at high speed.

Various modifications and changes can be made to the illustrated examples without departing from the scope of the present invention.

For example, the loop circuit 10 includes a pair of cation exchange towers and an anion exchange tower connected in series, but the number of stages can be increased depending on the type and amount of ions brought into the washing water tank 3. The exchange column and anion exchange column pair can be connected in series or in parallel with the illustrated pair. With this method, even if the conductivity of the treated water returned to tank 6 is set to about 0.5 μS/cm, the circulation time during which water sampling is stopped can be kept to less than 20% of the total, and fluctuations in water quality in washing tank 3 can be avoided. There was no effect on

While the exchange capacity of the ion exchange tower and/or A remains (not shown here), there will be a change in the conductivity before and after that, and this will be detected, and when this difference falls below a predetermined value, , Replaced with a separately prepared recycled exchange tower,
The removed exchange tower will be regenerated separately using standard methods. It is convenient to prepare multiple columns in advance for such exchanges.

Although not shown in the drawing, if filter F is gravity filtration, if it becomes clogged, fresh cleaning water is introduced from tank 6 downstream of the filter and backwashed to remove the water-insoluble matter that has adhered to it. This combination is preferred because it can be washed away and regenerated.

The device of the present invention is equipped with a loop circuit that circulates through the cation exchange tower and the anion exchange tower, so that short circuits that occur can be repaired, so cleaning water can be recovered as high-quality cleaning water compared to conventional devices. Can be done. Furthermore, since the ion exchanger is separated into anions and cations,
It has the feature that it can be updated just in time depending on the quality of the washing water. As a result, the amount of bayone exchange resin used could be reduced by half compared to the conventional method. The cost was significantly reduced compared to the cost of installing a mixed bed column, which is essential for high-level deionization.

In this manner, the present invention enables a closed system that does not discharge wastewater containing pollutants to the outside at low cost.

[Brief explanation of drawings]

The drawing is a schematic diagram of a specific example of the device of the present invention. 1 is a chemical conversion treatment tank, 2 is a liquid recovery tank, 3.4 is a washing tank,
5 is a used washing water tank, 6 is a treated washing water storage tank, 10 is a loop circuit, F is a filter, K is a cation exchange tower, and A is an anion exchange tower.

Claims (2)

[Claims] (1) In a closed-type washing system in which chemically treated articles are washed in a washing tank and the used washing water is purified and then returned to the washing tank, anion exchange is performed with at least one set of cation exchange towers connected in series. A column is provided so that the used washing water from the washing tank is purified through the set of ion exchange towers and then circulated to the washing tank, and further connects the downstream of the set of ion exchange towers and the upstream of the ion exchange tower. A loop circuit is provided, and when the conductivity of the wash water after passing through the set of ion exchange towers is above a predetermined value, the wash water is circulated within the loop circuit until the conductivity becomes below the predetermined value. and when the conductivity of the washing water after passing through the set of ion exchange towers is less than a predetermined value, the loop circuit is closed and the washing water that has passed through the ion exchange towers is returned to the washing tank. A water washing device for chemical conversion treated articles, characterized by comprising means for controlling the flow of washing water. (2) The apparatus of item 1, wherein the used wash water is filtered by a gravity filter before being introduced into the set of ion exchange towers.