JP3446355B2 - How to clean metal strips - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a metal strip which is continuously treated with chemicals such as pickling, electrolytic treatment and plating.
Next, the present invention relates to a method of washing the treated metal strip with water to wash away the residual chemicals.

[0002]

2. Description of the Related Art Generally, water cleaning after chemical treatment of metal strips is performed by spraying about 1 to 3 stages or a combination of a dipping tank and ringarol, and replenishing fresh water with a spray washing tank or a dipping tank at the final stage. It is done in the wash tank. The number of steps and the amount of make-up water are determined by the approximate residual concentration of the chemical component on the metal strip and the experience from past facilities when designing the facility, and once determined,
Usually, it was usually fixed and used regardless of changes in operating conditions such as liquid concentration, metal strip plate thickness, and line speed. This is because in Japan, water is relatively abundant and cheap, so it does not affect product quality, and even if these values were decided at a fairly safe value, they could be ignored economically.

[0003]

However, in the above-mentioned cleaning method, for example, when water is insufficient in the summer and water supply is restricted, it is difficult to reduce the amount of cleaning water without affecting the quality. Moreover, when installing a plant in an area where water is not always abundant, such as overseas, the conventional method has not always been economically optimal.

An object of the present invention is to provide a cleaning method capable of cleaning a metal strip with a minimum amount of fresh water supply for the purpose of solving the above problems.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a cleaning method for treating metal strips continuously in a chemical agent and cleaning the metal strips in a washing water spray or a dipping bath between multiple ringer rolls and each ringer. It is a method of cleaning a metal strip, characterized in that the amount of water supplied is determined by the concentration of permissible chemicals in the wastewater discharged from the facility . Well
The fresh water supply Q _W in this method is calculated by the following equation (1).
May be determined so that Further, the present invention processes the metal strip continuously in the drug, when cleaning a metal strip in the wash water spray or immersion bath between multistage wringer roll and the ringer, metallic strips bring after drug treatment Measure the amount of chemical liquid and calculate the value from the following formula
A method for cleaning a metal strip is characterized in that the fresh water supply amount Q _W for cleaning is determined so as to satisfy (1) .

Q _W ＞ (α _A / α _C ) ・ Q _A ………… (1) where α _A : concentration of chemical solution tank α _C : acceptable concentration of chemical agent in water treatment facility Q _A : from chemical treatment tank This is the amount of drug solution to be brought out.

Further, in the present invention, when the metal strips are continuously treated in the chemical and the metal strips are washed in a washing water spray or a dipping bath between the multi-stage ringarol and each ringarol, the ringallol and each ring A method for cleaning a metal strip, wherein the number of cleaning water spray stages between linger rolls is determined from the allowable chemical concentration remaining on the facility outlet strip, and in the present invention, the number of cleaning water spray stages n is defined by 2) based on
It is a method of cleaning a metal strip, characterized in that it is determined so that _An <α _S.

[0008]

[Equation 2]

Further, the present invention is characterized in that, in each of the above inventions, a multi-stage ringer roll and a wash water spray are provided between each ringer roll, and the number of stages used for each ringer roll and wash water spray can be arbitrarily switched. It is a method of cleaning a metal strip.

[0010]

FIG. 3 (a) shows a conceptual diagram of general chemical treatment of a metal strip. The metal strip 1 is subjected to a chemical treatment in a chemical bath 4 and subjected to a liquid squeezing in a ringer roll 2, and is washed in a washing bath 5 with a water spray from a washing header 3.
And the washing tank 5 is connected in several steps. Further, a part of the washing tank 5 may be a brush scrubber or a dipping tank. In addition, as for the way of sprinkling water, fresh water is sprinkled in any of the washing tanks in this figure, but in general, some sub-tanks 6 may be provided and used in a cascade. The cleaning water thus applied enters the sub tank 6 and is sent to the water treatment facility 8 by the drainage pump 7. This is seen from the viewpoint of water balance in FIG. 3 (b). The chemical solution is brought in from the chemical solution tank 4 at Q _A (l / min), diluted with the new water supply amount Q _W (l / min), and then sent to the water treatment facility 8.

[0011] That is, feed rate Q of the water treatment facility _{8, Q = Q A + Q W} ≒ Q W (Q A «Q W) is ............ (3), the dilution ratio X is, X = Q _A / Q _W ………… (4).

Generally, in a water treatment facility, there is a limit to the permissible chemical concentration α _C that can be received, from the viewpoint of the ability to remove chemical liquid components in waste water. Assuming that the concentration in the chemical tank is α _A , the drainage concentration α is α = α _A × X = α _A (Q _A / Q _W ) ... (5), and the condition for accepting water treatment is α <Α _C ………… (6), and from this and the formula (5), the required new water supply Q _W
Is Q _W > (α _A / α _C ) · Q _A ………… (7).

That is, it is understood that the fresh water supply amount Q _W may be determined by the equation (7). Next, FIG. 4 shows the dilution in each washing tank. The liquid squeezed with the ringer roll 2 from the chemical solution tank of the concentration α _A is carried out to the metal strip with the liquid film thickness t (upper and lower). The amount Q _A of the chemical solution brought out is Q _A = t · W · V (8) as the plate width W and the plate speed V. Here the wash water of the washing header 3 from the water Q _W1 drug concentration in water in the (vertical) alpha _W1 is applied, it is a liquid which is diluted to a concentration alpha _A1, squeezed by the following ringer roll. Here, α _A1 is expressed by the following equation (9).

[0014]

[Equation 3]

Since the same applies to the second and subsequent stages, it can be approximated by the following recurrence formula.

[0016]

[Equation 4]

Allowable drug concentration α remaining on the metal strip
_{As S} , it can be seen from the equation (11) that the required number of cleaning water spray stages n should be determined.

[0018]

[Equation 5]

[0019]

EXAMPLES The present invention will be described below based on examples.
FIG. 1 is an explanatory diagram showing an example of a method according to the present invention. The metal strip 1 passes through the chemical liquid tank 4 and then enters the water washing tank 5.
The washing tank 5 is divided into several stages by the ringer rolls 2, and a washing header 3 is installed between each ringer roll. An automatic valve 11 is installed in the supply pipe to each washing header 3, and the number of washing stages can be changed according to the calculation result of the process computer (P / C) 12. Further, a flow control valve 9, a flow meter 10, and a flow controller 18 are installed in this washing water supply unit, and the amount of fresh water supplied can be changed according to the calculation result of the process computer 12. Then, the water used to wash the metal strip is finally guided to the sub tank 6,
Liquid is sent to the water treatment facility 8 by the drainage pump 7. Further, the chemical solution is replenished from the stock solution tank 17 to the chemical solution tank 4 by the replenishment pump 16 in correspondence with taking out of the strip.

In the equipment having the above construction, a liquid film thickness meter 14 is installed on the process liquid side of the process computer 12, and the value t and the line speed V obtained from the output of the PLG 13 installed on the bridle roll 19, The board width W given from the host computer (H / C) 20
Amount of chemical liquid carried out by the metal strip Q _A = t ・
Calculate W · V. Next, the fresh water supply amount is calculated by the equation (7), and the value is set in the flow rate controller (FIC) 18. Accordingly, the flow rate controller 18 determines the opening degree of the flow control valve 9 by comparing the measured value of the flow meter 10 with the set value.
Further, the process computer 12 calculates the required number of cleaning water spray stages from the equation (11), and as a result determines whether to open or close the automatic valve 11 and the ringer roll 2.

In the above description, the output of the liquid film thickness meter was used to determine the carry-out amount Q _{A of the} chemical liquid, but it may be calculated from the plate width and the plate speed assuming the film thickness to be a certain value. Also, as the value of Q _A, the amount of the stock solution supplied to the chemical solution tank is measured by the flow meter 15,
It can also be used. It is also possible to directly measure the wastewater concentration with the densitometer 22 and determine the new water amount Q _W.

FIG. 2 is an explanatory view showing another example (cascade method) of the method according to the present invention. In this example, the usage of the wash water is cascaded, but the method of supplying fresh water, that is, the usage of the flow control valve 9, the flow meter 10, and the flow controller 18 is the same as in the example of FIG. In this embodiment, the process computer 12 calculates the required number of cleaning water spray stages from the equation (11), and as a result determines whether the ringer roll 2 is opened or closed and the pump 21 is operated or stopped.

In addition to the above two examples, it is conceivable to use one part of each cleaning water spray stage as a brush scrubber or to adopt an immersion tank system instead of a spray system.

[0024]

According to the present invention, it becomes possible to reduce the washing water for the metal strip after the chemical treatment.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a method according to the present invention.

FIG. 2 is an explanatory diagram showing another example of the method according to the present invention.

FIG. 3A is a conceptual diagram of a general metal strip chemical treatment, and FIG. 3B is an explanatory diagram showing water balance.

FIG. 4 is a conceptual diagram showing a dilution situation during cleaning.

[Explanation of symbols]

1 metal strip 2 Lingalore 3 Washable header 4 chemical tank 5 water washing tank 6 sub tank 7 drainage pump 8 water treatment equipment 9 Flow control valve (new water supply) 10 Flowmeter (new water supply) 11 Automatic valve 12 Process computer (P / C) 13 PLG (Line speed measurement) 14 Liquid film thickness meter 15 Flowmeter (stock solution, totalized) 16 Supply pump 17 Stock solution tank 18 Flow controller (new water supply) 19 bridle rolls 20 Host computer (H / C) 21 pumps 22 Densitometer

Claims (6)

(57) [Claims] 1. When the metal strips are continuously treated in the chemical and the metal strips are washed with a multi-stage ringa roll and a washing water spray between the ringa rolls or a dipping tank, the fresh water supply for washing is supplied from the equipment. A method for cleaning a metal strip, which is characterized in that it is determined according to an allowable chemical concentration in discharged wastewater. 2. A chemical solution carried out by the metal strip after the chemical treatment when the metal strip is continuously treated in the chemical and the metal strip is washed by a multi-stage ringarol and a washing water spray or a dipping bath between the ringarols. the amount was measured, a metal strip cleaning method and determines the cleaning fresh water supply amount Q _W so as to satisfy the following equation (1) from the value. Q _W ＞ (α _A / α _C ) ・ Q _A ………… (1) where α _A : Concentration of chemical liquid tank α _C : Acceptable chemical concentration of water treatment facility Q _A : Taken out from chemical treatment tank The amount of liquid medicine . 3. A washing fresh water supply amount Q _W that definitive to claim 1, the method of cleaning metal strip which satisfies the following equation (1). Q _W ＞ (α _A / α _C ) ・ Q _A ………… (1) However, α _A : Concentration of chemical liquid tank α _C : Acceptable chemical concentration of water treatment facility Q _A : Taken out from chemical treatment tank The amount of liquid medicine. 4. A metal strip is continuously treated in a chemical agent, and when washing the metal strip in a multi-stage washing water spray or a dip bath, the washing between the ringaroles and the respective ringaroles is performed. A method for cleaning a metal strip, characterized in that the number of water spray stages is determined from the allowable chemical concentration remaining on the strip on the outlet side of the facility. 5. The number of cleaning water spray stages n according to claim 4.
Is determined so that α _An <α _S based on the following recurrence formula (2). [Equation 1] 6. The washing water spray is provided between the multi-stage ringer roll and each ringer roll, and the number of stages used for each ringer roll and the washing water spray can be arbitrarily switched. 4. The method for cleaning a metal strip according to 4 or 5.