JPH08218189A - Evaporation treatment of washing water for surface treatment - Google Patents

Abstract

PURPOSE: To decrease the rates of the washing water to be supplied and drained in surface treatment. CONSTITUTION: The works stuck with liquid chemicals are prewashed in an intermediate zone between a liquid chemical zone and a washing zone by using a part of the washing water of the ensuing stage and the water used for the prewashing is introduced as it is to an evaporation device without discharging the waste water of washing at the time of subjecting the works to degreasing or chemical conversion treatment, etc., in a tunnel-shaped booth type continuous pretreating device 1 before coating, then subjecting the works to plural stages of washing of the ensuing and succeeding stages. Further, the works are blown with air on the outlet side of the liquid chemical zone and after the liquid chemicals adhered thereto are blown off, the works are transferred to the prewashing zone.

Description

Detailed Description of the Invention

[0001]

The present invention relates to degreasing and cleaning of metal surfaces,
The present invention relates to a spray-type surface treatment method used for purposes such as phosphate treatment, and particularly to a washing water evaporation treatment method.

[0002]

2. Description of the Related Art As a pretreatment method for degreasing metal products, phosphate treatment, etc., a tunnel-shaped booth is divided into a plurality of spray chambers, and a spray mechanism and a spray liquid reservoir are provided in each spray chamber. BACKGROUND ART A method of performing cleaning and chemical conversion treatment while sequentially transferring an object to be treated from a chemical treatment zone to a water washing zone subsequent to the next stage by a conveyor is used. In this treatment method, the carry-in of the chemical solution to each washing zone is increased, and in order to prevent the cleaning effect from being lowered, conventionally, fresh water is supplied to the final zone of each washing zone, and overflows sequentially to the preceding zone, The water was drained from the first washing zone following the chemical solution zone. For this reason, wastewater was constantly generated, and it was necessary to treat this wastewater. As a countermeasure against this, the inventors of the present invention discharge the steam from the upper part of the chemical solution zone, control the amount of water equivalent to the evaporated water and sequentially replenish it by spraying from the latter stage, thereby substantially saving water and eliminating the constant drainage. Succeeded in obtaining a patent. (Japanese public 1992 4
8876) This method is a very excellent method that can virtually eliminate drainage at all times, but on the other hand, it has the following problems.

[0003]

[Problems to be Solved by the Invention] The carry-out of the chemical liquid to the next stage and thereafter is extremely reduced, and the taken-out chemical liquid is almost returned to the chemical liquid zone, so that the chemical liquid is deteriorated. In the degreasing process, oil etc. are mixed in the same way as before,
There was not much difference as the deterioration progressed, but it still tended to be faster than when it was constantly drained.

Phosphate treatment, especially zinc phosphate treatment in combination with an accelerator, accumulates sodium ions, and the liquid components cannot be balanced, so that a certain amount must be drawn or the liquid must be periodically renewed. there were. The present invention provides a method for evaporating washing water for surface treatment, which eliminates the above-mentioned drawbacks and substantially eliminates drainage at all times.

[0005]

[Means for Solving the Problem] In order to achieve this object, the present invention returns the preliminary washing spray water from the latter stage to the chemical solution zone as in the above-mentioned patent (Japanese Patent Publication 48876) which eliminates constant drainage. Instead, it was led to the outside of the system at an intermediate position between the chemical solution zone and the next water washing zone, and was evaporated and concentrated. Concentrate the liquid as industrial waste and outsource it to a disposal company. As a result, the chemical solution carried out by the treated product is removed to the outside of the system as in the conventional case, so that the chemical solution is not deteriorated and the contamination of the rinse water in the rinse zone is reduced. Of course, a small amount of washing water is enough, so it can be evaporated with a little fuel consumption. Further, pressure air piping is provided on the outlet side of the chemical liquid zone, and pressure air is applied to the treated material to drop the adhered chemical liquid so as to squeeze the chemical liquid into the chemical liquid zone, thereby reducing the carry-out of the chemical liquid to the next stage. As a result, the degree of chemical contamination in the washing process is lowered, and it is possible to keep the degree of contamination in the washing process low by supplementing a small amount of fresh water. Therefore, the fuel consumption when evaporating the waste water can be further reduced.

[0006]

In the surface treatment water washing and water evaporation treatment method according to the present invention configured as described above, the treated material is subjected to surface treatment in the chemical solution zone, then transferred to the draining section, spray-washed, and spray-washed. The wash water is drained out of the system. After the treated material is spray washed, it is transferred to the next and subsequent washing zones for further thorough washing.However, when washing in the washing zone, the chemical liquid adhering to the treated material is the chemical liquid zone and the washing zone. Since it is spray-washed at an intermediate position and sufficiently diluted, the accumulation of contamination in the washing tank is extremely low. In addition, by squeezing out the chemical solution adhering to the processed material with pressure air at the outlet side of the chemical solution zone, the amount of contamination brought into the washing tank is further reduced, and the supply of fresh water can be further reduced while suppressing the degree of contamination. . As a result, it is possible to reduce the amount of water supplied to the flush tank, and to effectively maintain water and maintain pollution level control. Therefore, the amount of flush water to be drained is extremely small, so that the drainage can be efficiently evaporated and the drainage can be eliminated at all times. On the other hand, the chemical liquid is also discarded as waste water, so that deterioration is eliminated.

[0007]

EXAMPLE Next, an example in which the present invention is applied to a pretreatment process for metal coating will be specifically described with reference to the accompanying drawings. FIG. 1 is a flow chart showing an embodiment of the present invention, 1 is a tunnel booth, 2 is a conveyor, 3A is an entrance, 3B
Is a preliminary degreasing part, 3D is a main degreasing part, 3F, 3H, 3J is a water washing part after degreasing, 3L is a film forming part, 3N, 3P, 3R,
3T is a water-washed part after film formation, 3C, 3E, 3G, 3I,
3K, 3M, 3O, 3Q, and 3S are draining parts, and 3U is an exit part of the processed material. Each processing section is accompanied by a 6B to 6T storage tank, and the liquid in the storage tank is sent to each processing section by the circulation pumps 5B to 5T through the respective pipes and sprayed from the spray nozzles 4B to 4T to the storage tank again. It is returned and sprayed for circulation. Also, the first washing tank 6F,
Second washing tank 6H, third washing tank 6J, and fourth washing tank 6
N, 5th washing tank 6P, 6th washing tank 6R, 7th washing tank 6T
The liquid sent from each of the reservoirs through the respective pipes by the circulation pump is sent to the spray nozzles of the respective processing parts and is also sent to the respective liquid draining parts of the preceding stage by the bypass pipe branched from the respective pipes, and the spray nozzles 7E, Liquid is sent to the 7M and the outlet side of the pretreatment unit, and spray nozzles 7G, 7I, 7O, 7
It is designed to be sprayed from Q and 7S. Here, the washing water sprayed by the spray nozzles 7E and 7M drops, and then passes through the conduits 16E and 16M to drain the drainage tank 1 outside the system.
Sent to 7. Spray nozzles 7G, 7I, 7O, 7
The washing water sprayed from Q and 7S is dropped and then returned to the respective 6F, 6H, 6N, 6P and 6R storage tanks in the preceding stages. In the reservoirs 6J and 6T, since there is no water supply from the water washing section in the subsequent stage, fresh water is supplied through the pipe 14 by the spray nozzles 8K and 8U while adjusting the flow rates with the water supply valves 9K and 9U, respectively.

The object to be subjected to the pre-coating treatment is hung by a hanger attached to the conveyor 2 and continuously transferred into a tunnel-shaped booth, and degreasing-washing-film forming while passing 3A to 3U. ~ Washed with water. After that, after passing through the outlet portion 3U, draining, drying, painting and the like are performed.

Here, a process in the tunnel-shaped booth 1 will be described in detail. The processed material transferred to the inlet section 3A is then transferred to the preliminary degreasing section 3B. The preliminary degreasing unit 3B forms a chamber in which the preliminary degreasing liquid in the reservoir 6B is sprayed from the spray nozzle 4B through the pipe by the circulation pump 5B. The processed product preliminarily degreased in the preliminary degreasing unit 3B is transferred by the conveyor 2 and passes through the liquid draining unit 3C, and then is transferred to the main degreasing unit 3D. Preliminary degreasing liquid adhering to the treated material drips in the liquid draining section 3C, but the bottom of the liquid draining portion (called a drain pan) forms a watershed at approximately the center, and the dropped preliminary degreasing liquid is separated by a watershed. It falls on the reservoir 6B side of the degreasing section and returns to the reservoir 6B for the preliminary degreasing liquid,
The liquid dropped on the side of the reservoir 6D of the degreasing unit is the reservoir 6 for the degreasing liquid.
Flow into D. Subsequently, the processed product is degreased in the main degreasing section in the same manner as in the preliminary degreasing step, and transferred to the draining section 3E.

In this degreasing unit, the pressure of the compressed air sent from the compressor 15 immediately before being transferred to the liquid draining unit is adjusted by the pressure adjuster 10 and is sprayed onto the object to be processed through the pressure air pipe 26. It is effective that the blowout portion of the pressure air is blown aiming at a portion where the liquid is likely to collect. In this manner, the degreased liquid is transferred to the liquid draining section 3E while minimizing the amount of the degreased liquid adhering to the processed material and being brought into the next step, and is transferred to the washing water spray nozzle 4F in the first water washing step at the liquid draining section 3E. The nozzle 7E, which is branched from the pipe to be sent by a bypass pipe and sprays the liquid, is prewashed before the spray washing process of the first washing process. The water used in the first washing step used for the preliminary washing is collected by the drain pan of the liquid draining section 3E and sent to the drainage reservoir 17 through the conduit 16E. After that, they are sequentially transferred and washed to drainage, but on the third floor, 3
The spray washing water that has been prewashed at the outlet side of H (or may be prewashed at the liquid draining portions of 3G and 3I) flows into the reservoirs 6F and 6H at the preceding stages, respectively.

Next, the processed product transferred to the 3K draining section is sprayed with fresh water by the spray nozzle 8K to wash the processed product, and then flows into the third washing water reservoir 6J. Similar to the degreasing step, the film formation part 3L and the following 4th to 7th
The same process is applied to the washing section. In the attached drawings, the mechanism for blowing out the pressurized air is omitted on the outlet side of the film forming portion 3L, but the amount of the liquid taken out can be reduced by connecting the piping. Also, the number of washing steps following the film formation part is one more than the number of washing steps in the degreasing part is three steps, but since it is effective in reducing the degree of contamination of the washing water, it is not necessary to use four steps. Absent.

The treated product thus treated is spray-washed with fresh water at the outlet side of the seventh water washing section 3T or at the outlet section 3U, and then transferred to a draining drying furnace-coating step-transfer.
The fresh sprayed water flows into the reservoir tank 6T of the seventh water washing section. The washing water spray-washed by the spray nozzle 7M is also collected in the same manner as the washing water sprayed by 7E and sent to the drainage reservoir 17 through the conduit 16M.

11A and 11U are exhaust ports for the generated steam, and fans 13A and 13 are passed through ducts 12A and 12U.
Exhausted by U. This is a general method in which the chemical solution is usually heated and used, so that the steam is forcibly discharged from the tunnel-shaped booth so that the steam does not drop at the entrance and exit.

Since the treated product thus treated with the chemical solution is continuously washed with water in the subsequent steps and thereafter, the washing water is contaminated with the chemical solution. Therefore, the adhering chemical liquid is squeezed out by pressure air at the outlet side of the chemical liquid process. Alternatively, the water is preliminarily rinsed at a liquid draining section located at an intermediate position between the chemical solution treating section and the water rinsing section, and the preliminarily rinsed rinse water is highly contaminated with the chemical solution and therefore is not returned to the rinse water tank but drained and sent to the evaporator. If these methods are used to prevent chemicals from being brought into the washing tank as much as possible, the degree of contamination of the washing water will be low. Preliminary washing is also carried out in the subsequent water washing process as well, so that the effect is great, and as a result, in terms of pollution degree control, even if the supply amount of fresh water is reduced, the chemical solution pollution degree can be the same as the conventional one. As a result, the amount of wastewater is significantly reduced, and it is possible to achieve profitability by evaporating wastewater that had to be treated conventionally. Evaporation does not dry up but concentrates about 10 to 20 times, and the concentrated liquid is treated as industrial waste by a contractor.

Reference numeral 19 is a main body of the evaporation treatment apparatus, and a drainage tank 17
Wastewater is sent from the conduit 18 and the wastewater is vaporized by the burner 20. Reference numeral 21 is a fuel, and 27 is a perforated plate in the evaporator. The perforated plate promotes gas-liquid contact, and the vaporized exhaust gas passes through the exhaust duct 22 and the gas-liquid separator 23 and then through the exhaust duct 24 to the exhaust fan 25.
Exhausted by. In addition, as a matter of course, the evaporative device can use the exhaust heat of the coating baking furnace and the pre-treatment draining and drying furnace.

Next, the above example will be described with specific numerical values. Bed assembly member (SPC) 500 for processed products
The production line, which is treated at 0 m ² / day, was treated by the apparatus constituted by the flow chart of the attached drawings. Third after degreasing
The chemical dilution ratio (contamination degree) of 6J of wash water is 1/1000,
After the film formation, in order to control the degree of contamination of the 6th wash water 6R to 1/1000, where the treatment was performed without blowing pressurized air at the degreasing outlet side, it is necessary to supply fresh water 8K, 8U from the spray nozzle. The total volume was about 7,000 L / day.
Also, when pressure air is blown from the degreasing outlet side,
It was 000 L / day. Incidentally, the reason why the contamination degree is not controlled in the post-coating seventh water washing tank 6T is that pure water is supplied to the spray nozzle 8U in order to perform electrodeposition coating after pretreatment, and the actual contamination degree is controlled in the tank 6R. It depends on what you are doing.

As a result, 8000 L / day was sent to the evaporator without air blowing and 7,000 L / day was sent with air blowing. P. The amount of G used was 380 Kg / day and 326 Kg / day, respectively. Further, the concentrated liquid per day was generated at 130 L / day. If you calculate this on a monthly basis, the necessary expenses are water usage fee, sewer usage fee, concentrated liquid industrial waste cost, evaporator electricity fee, and fuel cost of 70,000 yen / month, 20,000 yen / month,
The total was 90,000 yen / month with 80,000 yen / month, 210,000 yen / month, and 540,000 yen / month. This is the case where the degreasing outlet side was treated without blowing pressurized air. When air was blown, it was 62,000 yen / month, 16,000 yen / month, 8
The total was 810,000 yen / month for 10,000 yen / month, 1840,000 yen / month, and 468,000 yen / month.

[0018]

[Comparative Example] Further, when the number of washing stages after each chemical solution treatment was performed at two with the same treatment amount, the water supply / drainage amount was 100,000 L /
I needed a day. The cost, water usage fee, and sewerage usage fee required for this wastewater treatment are 350,000 yen /
Monthly sales were 880,000 yen / month and 280,000 yen / month for a total of 15.1 million yen / month.

[0019]

EFFECTS OF THE INVENTION According to the method for evaporating washing water for surface treatment in the examples, even if the amount of washing water for washing used in the surface treatment step is reduced, the degree of contamination of the washing water is reduced. Can be maintained without incident. The cleaning water is efficiently replaced by the liquid having a high concentration attached to the treated material, and is drained without returning to the washing tank, so that the evaporation treatment can be performed at a low cost. For this reason, the device that has conventionally been used for wastewater treatment is not required. Further, since the chemical solution is also taken out of the system, deterioration of the chemical is eliminated. As a result, the water, sewerage, and wastewater treatment costs can be significantly reduced, and the excellent effects of eliminating deterioration of the chemicals used can be obtained.

[0020]

[Brief description of drawings]

FIG. 1 is a longitudinal side view flow chart of a phosphoric acid film chemical conversion treatment line according to the present invention.

[0021]

[Explanation of symbols]

1. … Tunnel booth 2. ... Conveyor 3A to 3U. ... Passing zones 4B to 4T from the inlet to the processing units, the liquid draining unit, and the outlet. 7E-7S. 8K. 8 U. ... Spray nozzle 5B-5W. ... Pumps 6B to 6T. ... Reservoir for chemical solution or washing water 9K, 9U. … Water supply valve 10. ... Air pressure regulator 11A, 11U. …. Exhaust port for generated steam 12A, 12U, 22, 24. ... Exhaust duct 13A, 13U, 25. Exhaust fan 14. … Fresh water supply port 15. ... Air compressor 16E, 16M, 18, 29. … Conduit 17. … Drainage tank 19. … Evaporator body 20. … Burner 21. … Fuel 23. … Iliminator 26. … Pressure air piping 27. ... Perforated plate 28. … Evaporation concentrate storage tank

Claims (2)

[Claims] 1. A surface treatment in which a treatment product is introduced into a tunnel-shaped booth, a surface treatment is performed with a treatment liquid containing a chemical liquid, and then the treatment product is sequentially transferred to a subsequent water washing zone and thereafter for cleaning. In the method, the treated product is placed at an intermediate position between the chemical solution zone and the next-stage water-washing zone by a bypass pipe branched from the spray pipe in the next-water wash zone, and the ratio of the spray water amount in the next-water wash zone is (1 ~ 0.1): Pre-spray water to 100, and adjust the amount of water corresponding to the reduced water amount in the next-stage water washing zone by a bypass pipe branched from the spray pipe in the next-stage water washing zone. Repeat the process of spray replenishing to the outlet side of the next washing zone so that the ratio with the spray water amount is (1-0.1): 100, and spray the amount of water commensurate with the decreasing water amount of the preceding stage at the outlet side of the final zone. A method for evaporating washing water for surface treatment, characterized in that the water that has been spray-washed is guided to the outside of the system at the intermediate position between the chemical solution zone and the next washing zone while replenishing and evaporating. 2. The method for evaporating washing water for surface treatment according to claim 1, characterized in that pressured air is applied to the object to be treated at the outlet side of the chemical solution zone to drop the adherent chemical solution into the chemical solution zone. Evaporative treatment method of washing water for surface treatment.