HU179961B - Device for recovering the electrolite carried out by treated pieces from surface treating bath - Google Patents

Abstract

Surface treatment tank contg. an electrolyte is provided on its inlet and exit sides with a rinsing tank and >1 pumps are used to circulate the liq. employed in these tanks so its composn. is the same in both. When the treatment tank contains a hot electrolyte, losses by evapn. are pref. replenished from one of the rinsing tanks. The liq. in these tanks is pref. water or a soln. which stabilises the electrolyte in the treatment tank. Used e.g. in plants for electrodeposition of Cu, Ni or Cr, where the recovery is ca. 88-89%.

Description

The present invention relates to an apparatus which provides, in a simple and easy manner, a means for recovering electrolytes, chemicals from surface-treated baths, such as galvanic baths, pickling baths, etc., from the workpiece. The recovery of electrolytes is of great economic and environmental importance.

The problem of electrolytes discharged from surface finishing baths has long been of concern to industry practitioners, and various solutions have been devised to reduce losses and avoid environmental damage as much as possible. The main solutions known to us are described below with reference to the drawings, and then with the aid of the drawings, a description of our own solution.

i List of figures:

^Figure 1. Various known flushing systems.

Figure 2. Two-bath recovery system.

Figure 3. Two-tub recovery system to compensate for evaporation losses.

Figure 4. Four-tub recovery system to compensate for evaporation losses.

Figure 1 illustrates the four rinsing methods currently used in the surface finishing industry. 25

The most recently used rinsing method is rinsing in a non-draining standing water bath (Figure 1 1.1).

Workpieces lifted from the surface finishing bath 1 are rinsed by dipping into the standing water rinse bath 2. Depending on the useful volume of the rinse bath and the amount of electrolyte 179961 applied, the rinse water must be renewed more or less frequently. In this case the contaminated rinse water is discharged into the purifier 3 and the standing water rinse bath 2 is filled with fresh water. The direction of movement of the product is indicated by the arrow 5.

A more effective way of rinsing is by rinsing in a flush bath (Fig. 1, 1.2).

Workpieces lifted from the surface finishing bath 1 are flushed in the flush water bath 4. The valve 4.1 passes the running water into the flushing bath 4, from where it is discharged through the outlet of the bath into the cleaning device 3. The direction of movement of the product is indicated by the arrow 5.

A water-saving, modern way of flushing water with rivers is countercurrent cascade flushing (Fig. 1, 1.3).

The workpieces are rinsed out of the surface finishing bath 1 in the direction of the arrows 5 in compartments 6.1, 6.2 and finally 6.3 of the countercurrent cascade flusher. The final rinse takes place in the compartment 6.3 where clean rinse water flows through valve 4.1. The flow direction of the flushing water is opposite to that of the product. Contaminated flushing water is transferred from compartment 6.1 to purifier 3.

Spray flushing is also used to increase the efficiency of flushing water (Fig. 1, 1.4).

The workpieces are rinsed out of the surface finishing bath 1 in the flush water bath 4. After rinsing, even above the 4 flush water baths, the highlighted parts are further rinsed with water spray with the help of the nozzle 4.2. In the 4 flush water tanks, clean water comes through valve 4.1. The dirty bay

-11799 (, 1 flushing water 1 enters purifier 3. The direction of product travel is indicated by arrow 5).

Common features of the described flushing procedures are:

- in the direction of product travel, the rinses are located after the surface finishing baths;

- the flushing water enters the purification system intermittently or continuously, where it is chemically decontaminated, neutralized or decontaminated according to official regulations. after converting pldptt metal ions into metal hydpxidpk and separating it into the receiver. Chemicals entering the treatment plant are generally wasted, even regenerations of state-of-the-art ion-exchange treatment plants cannot be used to replace chemicals carried out from surface finishing baths.

In the industry, devices based on the spray-evaporation principle have recently appeared, which are capable of returning the electrolyte to the rinse water, after appropriate concentration of the rinse water, to the surface finishing bath. Such as Blasberg RS 80 spray-evaporator.

The disadvantage of this process is the high energy consumption and space requirements. Its proper operation can only be ensured by highly automated control. For some electrolytes, it may only work with special surface finishing chemicals. This solution does not eliminate the cleaning equipment needed to detoxify irreparable baths.

A solution similar to the Blasberg RS 80 spray-evaporation recovery system is known from British Patent No. 1,482,941.

French Patent No. 2,444,725 addresses the problem in another way. In this solution, cascade countercurrent flushing as shown in Figure 1.3 is used. Rinse water from the countercurrent rinse, which contains a large amount of electrolyte, is led to a circulating filtration system, where it is cleaned of mechanical impurities, its pH is corrected and the solution is returned to the galvanic bath.

A disadvantage of the described and prior art solutions is that returning the electrolyte content of the recycled rinse water to the galvanic bath is only a costly cleaning or cleaning process. possible after evaporation. Regeneration always requires a significant amount of energy. In many of the solutions used in practice, recirculation is not solved and, at best, only ensures that the flushing water entering the purification system is chemically cleaned so that it can be discharged into the sewer in compliance with environmental regulations. The valuable electrolytes produced are present in a form which cannot be converted economically to the galvanic salt. Therefore, in most cases, they are wasted and may eventually end up being environmentally damaging again.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a surface finishing device which, by combining simple elements, provides a novel and hitherto unknown solution for the recovery of discharged electrolytes and a solution to the drawbacks of the known solutions.

An object of the present invention to achieve the above object is an apparatus for recovering electrolyte discharged by a workpiece from surface finishing baths, comprising tubs, piping and a pump, characterized in that an electrolyte recovery bath and an electrolyte dissolving tub are disposed immediately after the surface finishing bath. the tubs are connected to one another by a circulating pump. The apparatus works by dissolving the electrolytes (chemicals) remaining on the surface of the workpiece removed from the finishing bath in a bathtub placed after the bath. The dissolved electrolyte in this bath is returned to the finishing bath by recirculating the contents of the tub to the pre-finishing bath in a continuous operation by pump. From this pre-finishing bath, the workpieces are immersed in this tub before entering the finishing bath.

The present invention is described in detail below.

The simplest embodiment of the present invention is shown in Figure 2. The direction of movement of the workpieces is indicated by the arrow 5. Immediately before and after the surface finishing bath 1, the recuperator 7 and 8 are installed. discharge tub. Baths with rinsing fluid or rinse water or so-called "electrolyte stability" ensure are filled with stabilizing solution. The stabilizing solution is chosen so that it does not in any way alter the mechanism of action of the electrolyte. The recovery tubs 7 and decommissioning tubs 8 are connected by a pipe 12 formed according to FIG. During the operation of the pump 6 connected to the pipeline 12, it continuously circulates the liquid in the tubs so that from the recovery tub 7 in the pressure direction of the pump 6 shown in FIG. through the suction port of the pump 6. The purpose of circulating the rinsing liquid with the pump 6 is to ensure that the concentration of rinsing liquids in the tubs is the same.

Operation of the recovery system as shown in Figure 2:

At start-up, the tubs are filled with flushing fluid, and the pump 6 in operation continuously circulates the flushing fluid.

From the preceding sections of the surface finishing line, which are known and not subject to the present invention, the workpieces bring flushing water in the recesses of their surface. The workpieces are first immersed in the recovery bath 7 according to the session and then placed in the surface finishing bath 1. After finishing the surface finishing operation, the workpieces are immersed in the drain pan 8, and then the workpieces proceed to one of the known rinsing systems shown in Figure 1. The workpieces immersed in the discharge vessel 8 carry with them a certain amount of electrolyte from their surface recesses from the surface bath 1. The transferred electrolyte is not only diluted in proportion to the amount of flushing liquid in the bath 8, but also in proportion to the amount of flushing liquid in the recovery tank 7 via circulation with the pump 6. A properly selected pump, by correctly designing the inlet and outlet points of the piping 7 and 8 of the recovery tubs, can achieve a constant concentration of flushing fluid in the tubs 7 and 8 during a dipping cycle.

In the further steps, the rinsing fluid of the recovery bath 7 and the leaching bath 8 becomes increasingly concentrated in the electrolyte up to a certain limit value, in this case half of the bath electrolyte concentration. At this point, the workpiece 2179961 is supplied with the same amount of electrolyte from the recovery bath 7 to the surface preparation bath 1 as it does from the discharge vessel 8 to the further flushing system.

With this simple device according to the invention, half of the electrolyte deposited on the workpiece surface can be safely recovered from the cold working surface finishing bath in cases where the bath has no significant evaporation loss.

For surface finishing baths operating at hot temperatures above 40 ° C, the solution shown in Figure 3 is preferred. The recovery system differs in material from the apparatus described above in Fig. 2 in that the valve 4.1 is placed above the discharge vessel 8. The level reduction due to evaporation loss of the surface finishing bath 1 must be replaced by clean rinsing water. If the rinse water is continuously replenished with the bath rinse liquid, 55-66% of the electrolyte volume can be traced back to the surface preparation bath 1. Through the valve 4.1, clean rinsing water proportional to the evaporation volume of the surface preparation bath 1 must be continuously discharged into the rinsing liquid of the discharge vessel 8 or even of the recovery vessel 7. The liquid level in the discharge vessel 8 rises and gravitatively flows back to the surface finishing bath 1 in the direction of arrow 9. (The same solution is possible by analogy for the 7 recovery tubs.)

By doubling the recovery baths as shown in Figure 4, 66-90% electrolyte recovery can be achieved. This layout works as follows:

In front of the surface finishing bath 1 is located the recovery bath 7, and immediately thereafter the discharge bath 8, the flushing liquid of which is circulated by the pump 6. The tubs 10 and 11 are placed directly in front of the recovery tub 7 and the discharge tub 8 respectively. is installed. The tanks 10 and 11, which function analogously to the recovery and release tanks 7, are connected to each other by a pipeline, and their rinsing fluid is circulated by a pump 13 connected to the pipeline. Surface finishing bath 1 is hot and clean rinsing water to compensate for evaporation loss is continuously supplied through valve 4.1 to all additional drain pan, from where it flows through the overflow to drain pan 8 and then through the overflow to surface finisher 1. The direction of movement of the product is indicated by the arrow 5.

Advantages of the invention:

Low installation cost, very low power and space-saving, automated control equipment. Only the low power pump operating inside the unit requires maintenance.

The equipment can significantly reduce the amount of chemicals discharged from surface finishing baths and the same proportion of chemicals used in cleaning equipment. In addition to material savings, it also serves environmental purposes. Although the apparatus of the present invention does not achieve 100% efficiency, the low energy consumption (energy absorbed by the circulating pump) makes it more economical than the spray-evaporation apparatus.

Implementation Example:

In order to better illustrate the invention and illustrate its beneficial effects, the following examples are supplemented by the following, but are not intended to limit the invention.

In a galvanizing line, they are coated with 800,000 m ^{2 of} copper-nickel-chromium plating per year. The articulated workpieces are treated in a drum in the above surface baths. The electrolyte solution of the workpieces is 0.42 liter / m ² . The loss of electrolyte solution caused by the removal of workpieces is 33,000 liters / year per surface finishing bath.

Typical details for the surface baths in this example:

Copper bath:

total chemical content 113.00 g / 1 copper ion content 19.60g / 1 cyanide content 18.57g / 1 working temperature65 ° C

Nickel plating bath:

total chemical content 365g / 1 nickel ion content 60g / 1 working temperature 55 ° C

Chrome bath:

total chemical content 380g / l chromium (VI) ion content 197.6 g / l operating temperature 55 ° C

When this surface preparation device is constructed according to Figure 4 of the present invention, the following savings are achieved for each surface finishing bath:

Copper bath (recovery efficiency 89%):

Electrolyte chemical application

NaOH required for copper ion precipitation

G / l active chlorine sodium hypochlorite for complete decomposition of cyanides

Nickel-plating bath (recovery efficiency 88%): Electrolyte chemical application

NaOH required for nickel ion precipitation Electric energy

Chromium bath (88% recovery efficiency):

Electrolyte chemical application

Sodium bisulfite required for reduction of hexavalent chromium ion

For reduction of hexavalent chromium ion Sulfuric acid For precipitation of trivalent chromium ion NaOH

The invention The invention Savings before the introduction after the introduction 37,968 kg / year 4 176 kg / year 33,792 kg / year 8,297 kg / year 912 kg / year 7 385 kg / year 467,964 kg / year 51,476 kg / year 416,488 kg / year - 4,480 kW / year - 122,640 kg / year 13,490 kg / year 109 850 kg / year 27,417 kg / year 3 290 kg / year 24 127 kg / year 4,480 kW / year - 127,680 kg / year 15,321 kg / year 112,359 kg / year 132,787 kg / year 15,934 kg / year 116,853 kg / year 49 131 kg / year 5,895 kg / year 43 236 kg / year 153,369 kg / year 18 404 kg / year 134,965 kg / year - 4,480 kW / year -

-3A required to operate the electric gpergig g recirculation pump.

Claims (3)

J. Apparatus for recovering electrolyte discharged from 4 machined workpieces from surface baths, consisting of flanges, piping and a pump. characterized in that a separate electrolyte yolk bath (?) and a separate electrolyte trap (8) are placed immediately before the head bath (1) and the bath (1) and the steam recovery valve (7) and? elektrp | jj trigger (8) circulating HEART | typ (6) in connection with vgp (Figure 2), 2. A? Embodiment according to claim 1, characterized in that the evaporation loss of the over-delay bath (1) is replaced by a steam electrolyte Igoid bath (8). 3. A? Embodiment according to claim 1, characterized in that the electrolyte in the recovery tank (7) and the? water in the electrolyte baffle (8) at start-up, stabilizing solution of water or electrolyte stability-