JPS6134182A - Waste-waterless type surface treatment - Google Patents

Abstract

PURPOSE:To decrease the amt. of the chemicals and washing water to be used and to execute an efficient surface treatment of a waste-waterless type by subjecting the liquid chemical for surface treatment or washing water to vacuum distillation and reutilizing respectively the resulting concd. liquid to the surface treatment and the condensate to washing. CONSTITUTION:Part of the liquid chemical is withdrawn by a pump 9 from a liquid chemical tank 3A and after the liquid chemical is heated through a heat exchanger 10, the liquid chemical is supplied to the evaporator 5 of a vacuum distillation device 4 in the surface treating method in which the material 2 to be treated is conveyed by a conveyor 1, is treated by the aq. soln. contg. chemicals in the above-mentioned tank 3A and is then washed with the water in plural stages of washing tanks 3B-E. The inside of the evaporator 5 is evacuated by a compressor 12 and the liquid chemical introduced therein is heated and concd. by the evaporated steam via a heat exchanger 6 for evaporation. The concd. liquid chemical is returned through a heat exchanger 10 to the tank 3A. The condensate condensed by the heat exchanger 6 is supplied through the exchanger 10 into a drain water tank 14 and is then returned through a conduit 16 into the tanks 3B-E, by which the water is reused.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides a surface treatment method, and more specifically, a non-drainage surface treatment method that reduces the total amount of acid used in cleaning water when a metal bottom surface is treated with a chemical solution and multiple stages of water. Regarding processing method.

(Prior art) Degreasing treatment, chemical conversion treatment, chromate treatment, etc. are commonly used as surface treatment methods for metals, and generally the object to be treated is completely immersed in a tank of chemical solution corresponding to the treatment purpose, or the object to be treated is immersed in a chemical solution. After the chemical treatment, the object to be treated is then washed with water, etc. As a means of doing this, multiple cleaning zones are provided following the chemical zone to remove particles that adhere to the object. A method is used to wash away the chemical solution.

(c) Problems to be Solved by the Present Invention) However, in the conventional surface treatment method, in the cleaning process, fresh water is simply replenished at the final stage and this water is sent forward through a tL-order overflow set or the like. Therefore, in cases where 2000 to 4000 da/s of chromium, a harmful substance, is included, such as in the process of chromate treatment of aluminum, a large amount of washing water is required to wash away the chromium adhering to the workpiece. As a result, a large amount of surplus water is generated, and this surplus water contains a considerable amount of chromium, making it difficult to remove chromium and treat wastewater.
There is a problem of high treatment costs, and drainage is regulated in some areas due to the pollution problem, which makes surface treatment itself impossible in some cases.

(Means for Solving the Problems) The present invention solves the problems of the conventional surface treatment methods as described above, does not discharge harmful substances contained in chemicals such as chromium as wastewater, and does not require chemicals or cleaning water. The purpose of this invention is to provide a method that can reduce the amount of water used and perform efficient surface treatment with virtually no drainage.

To achieve this objective, the present invention provides a surface treatment method in which a metal surface is treated with an aqueous solution (chemical solution) containing all chemical agents, and then washed with water in multiple stages. The system separates the liquid into drain water (condensed water) and returns the concentrated liquid to the chemical tank, while reusing the condensed water.

The condensed water separated and treated by the vacuum distillation device does not contain harmful substances, so it can be drained as is.
The present invention reuses this condensed water, and particularly preferably returns the condensed water to one of the zones of the multi-stage washing process and reuses it as washing water, thereby further improving the water saving effect. can do.

The surface treatment method according to the present invention can be applied to any of a dipping method, a spray set, or a combination of a dipping method and a spray set.

(Example) Next, the present invention will be specifically explained based on the accompanying drawings.

FIG. 1 shows an example of the non-drainage type surface treatment method according to the present invention, where 1 is a conveyor, 2 is an object to be treated, the treatment apparatus in this embodiment is configured as an immersion type apparatus, and a chemical tank 3
A, first washing tank 3B, second washing tank 3C, third washing tank 3D
, a fourth washing tank 3E is provided.

The 4i-1 vacuum distillation apparatus is equipped with an evaporator 5 and an evaporation heat exchanger 6 disposed in the evaporator. In this embodiment, the evaporator 5 has an area side connected to the chemical tank 3A and the take-out pipe 7, and the other side is connected to the return pipe 8 and the chemical tank 3.
Connected to A. The take-out pipe 7 is provided with a bomb f9 and a heat exchanger 10, and a part of the return pipe 8 passes through the heat exchanger 10.

On the other hand, on the evaporation zone side of the evaporator 5, there is a condarez 12.
One end of all steam extraction piping 11 is connected, and the other end of this steam extraction piping 11 is connected to the inlet side of the evaporation heat exchanger 6 described above. A drain pipe 13 is connected to the outlet side of the evaporative heat exchanger 6, and the drain pipe 13 is led to a drain tank 14 via the heat exchanger 10. A water guide pipe 16 having a bong f15 extends from the drain tank 14 to a desired zone n1, that is, a second zone in the illustrated example.
It is connected to a through nozzle 23 arranged above the washing tank 3C.

Inside each washing tank 3B to 3E, there is a circulation nozzle +
7A to 17D are arranged, and the feed pipes 18A to 1
8D and ponders 19A to 19D are provided, each of which forwards cleaning water to the previous stage. In this embodiment, this advance is configured as replacement water washing nozzles 20A to 20D, and a fresh water supply spray nozzle 21 is provided in the final washing tank 3E. Liquid level gauges 22A to 22F are provided in the chemical tank, each washing tank, and the drain tank.

Generally, an overflow pipe is provided between each washing tank, but since the present invention is a non-drainage device with a length of S and 2 tons, the overflow pipe V can be installed even without it.

At the time of surface treatment, the liquid treated material 2 is conveyed at a predetermined speed by the conveyor 1, and is treated with the chemical *IK in the chemical liquid tank 3A. In this embodiment, the chemical solution tank 3AK is immersed.

Next, above or in the vicinity of the chemical tank 3A, the adhering chemical solution is washed off by the washing water that is supplied from the first washing tank 3B in the next stage through the entire feed pipe 18A to the displacement washing Ssollet/nozzle 0A. Then, it is washed with water in the first washing tank 3B, and before moving from the first washing tank 3B to the second washing tank 3C, it is washed with the spray nozzle 20B for displacement washing. From F
Through a similar process, it reaches the final washing tank 3E, where it is sent to another chemical treatment process, drying process, etc.

The present invention is applicable to the above-mentioned operation. The chemical liquid is taken out from the chemical liquid tank 3A using the horn 9, and all of the chemical liquid is taken out by valve 17, followed by the heat exchanger 10, and introduced into the evaporator 5. At the same time, the consolenser 12 is activated to completely reduce the pressure in the evaporator 5. The chemical liquid introduced into the evaporator 5 from the chemical tank (A) and stored therein is evaporated under reduced pressure, and the generated chemical liquid vapor is taken out of the evaporator 5 through the steam extraction pipe 1, heated and pressurized by the combrella V12, and then sent to the evaporator. The liquid is fed under pressure to the evaporation heat exchanger 6 inside the liquid.

In addition, the chemical liquid in the evaporator 5 is heated by the latent heat of the steam, while the steam condenses through heat exchange and becomes drain water.
The drain piping 13 is sent to the drain water tank 14 through the heat exchanger 10.

The separated water stored in this drain tank 14 is sent to the J Niji water guide pipe 16 by the pump 15, and is sent to the first water washing tank 3B.
The surface of the object to be treated is washed away by spraying from a spray nozzle 23 provided at the top of the spray nozzle 23, etc.

On the other hand, the chemical liquid stored in the evaporator 5 is concentrated by separating water, and the concentrated liquid is returned to the return distribution f8 and returned to the chemical liquid tank 3A.

Then, an amount of water commensurate with the water attached to the surface of the object to be treated 20 and the water evaporated and reduced in the chemical tank 3A is supplied to the chemical tank 3A from the first washing tank 3B via the displacement washing spray nozzle 20A. n1 first washing tank 3B
K is replenished with the amount of water commensurate with the water loss from the displacement washing spray nozzle 20BK from the second washing tank 3C in the latter stage, and in the same way from the spray nozzle for replacing water in the latter stage to the respective n front-stage washing tanks. An amount of friendly water corresponding to the reduced amount is sprayed, and the final flushing tank is replenished with fresh water.

In this embodiment, the present invention is applied to an immersion type surface treatment apparatus, but it is of course applicable to a spray set or an apparatus that uses both immersion and spray. It is also applicable to a method in which stages are continuous or a method in which a combination of a chemical solution tank and a subsequent water washing tank is repeated in multiple stages.

Next, specific examples of the present invention will be shown.

Example I Chromate treatment was performed by the method shown in FIG.

The object to be treated was an aluminum radiator with a surface area of 1 to 7 pieces, and was treated at a rate of 70 pieces/hr.

The chromate solution has a chromium content of 3500 ppm, Su/JIi
/, 1.50001) I) nl, fluorine 20001) I
13 from the chromic acid liquid bath using a 5% aqueous solution containing
00 t/hr was fed into the evaporator and heated to a liquid temperature of 45°C.

■ As a result, 300 t/hr of drain water and 1000/-,/hr of concentrated liquid were generated in the evaporator, which were returned to the fine ice total chromic acid tank, while the drain water was stored in the drain water tank and 2. One radiator was used as replacement washing water in the washing tank, and 4.2 tons of gray water was generated in 5 seconds. At the same time, the fourth amount of water is used to replenish the amount of water attached to the object to be treated and the amount of decrease due to evaporation V.
0°35 t/piece of fresh water was injected from the nozzle of the washing water tank and sent sequentially to the previous stage.

■ As a result, the adhesion concentration of the chromate solution that had adhered to the surface of the workpiece was reduced to 1% before entering the first and second washing tanks.
/10, and before entering the 3rd and 4th washing tanks, it is
Each was diluted to 1/3. In addition, the fluorine concentration of 1700 da/l in the chromic acid liquid tank is 250 to 300 η in the first washing tank.
/1X 40-50η7t in the second washing tank.

15-20η/1 in the third washing tank. 3 to 1 in the 4th washing tank
It became constant at 0 da/l, and complete wastewater-free treatment was possible.

(Effects of the Invention) According to the present invention as described above, in a surface treatment method in which a metal surface is treated with an aqueous solution containing a chemical agent and then washed with water in multiple stages, harmful substances contained in the chemical solution are discharged as waste water. In addition, the amount of chemicals and water used can be reduced, and the excellent effect of efficiently performing surface treatment with virtually no waste water can be obtained.

It is an explanatory view showing one example.

3A...Chemical solution tank, 3B-3E...Washing tank, 4...
Reduced pressure distillation device, 5... Evaporator, 14... Drain tank, 16... Water guide piping, 23... Spray nozzle.

Patent applicant: Tokyo Electric Power Company, Inc. Same Chemicoat Co., Ltd. Representative Patent Attorney Kuro 1) Hiroshi Yasushi 1.

Claims (1)

[Claims] 1. A surface treatment method in which a metal surface is treated with an aqueous solution containing a chemical agent, and then washed with water in multiple stages, the surface treatment chemical solution or washing water being distilled under reduced pressure to obtain a concentrated solution. A non-drainage surface treatment method characterized by recycling condensed water as washing water while returning it to a chemical tank for surface treatment. 2. The non-drainage surface treatment method according to claim 1, wherein the surface treatment method is a dipping method. 3. The non-drainage surface treatment method according to claim 1, wherein the surface treatment method is a spray method. 4. The non-drainage surface treatment method according to claim 1, wherein the surface treatment method is a combination of a dipping method and a spray method.