JP2006169572A - Phosphate treatment apparatus for steel sheet, and method for reusing wasted washing water in phosphate treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phosphate treatment apparatus which can save washing water necessary for phosphate-treating steel sheet and a treatment liquid for forming a phosphate film without installing a large-scaled facility, and can reduce a running cost. <P>SOLUTION: This phosphate treatment apparatus comprises: a phosphate treatment solution circulation tank 5 which accommodates the treatment liquid for forming the phosphate film; a phosphate treatment tank 2 for forming the phosphate film on the steel sheet by using the treatment liquid for forming the phosphate film supplied from the phosphate treatment solution circulation tank 5; a rinse tank 4 for rinsing the steel sheet having the phosphate film formed thereon in the phosphate treatment tank 2; and a rinse tank 3 for recovering the treatment liquid, which is installed between the phosphate treatment tank 2 and the rinse tank 4, collects the rinse water having washed the steel sheet in the rinse tank 3, and returns the recovered rinse water of an untreated state to the phosphate treatment solution circulation tank as make-up water. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a steel plate bonder and a method for reusing washing wastewater in a bonder, and in particular, for recovering and reusing active components such as phosphoric acid contained in water in wastewater in a steel plate bonder. It relates to a technique suitable for use.

  Conventionally, galvanized steel sheets used for automobiles, home appliances, building materials, and the like are subjected to bondage treatment (phosphate treatment) and further subjected to organic coating treatment according to applications. The film formed by the bonde process is excellent in adhesion to the underlying metal surface and plating film, and also excellent in adhesion to the coating film formed on it. Widely used. In the bonder treatment, the phosphorylation treatment liquid is spray-coated on the object to be treated, or after the object to be treated is immersed and reacted in the liquid, the excess adhered to the metal surface through a plurality of water washing steps. The phosphating solution is washed away.

  The water washing step after the bonde treatment is important for stopping the film formation reaction, and in the absence of this water washing, the reaction proceeds partially due to the phosphorylation treatment liquid remaining on the steel plate and adheres. The amount becomes uneven and unevenness occurs. Further, since the phosphorylation treatment solution has corrosive properties, it is not preferable to make contact for a long time.

  In conventional bondage processing lines, washing waste liquid was discharged out of the system, which caused environmental problems and problems in effective use of resources. In recent years, various proposals have been made to solve such problems.

  For example, washing wastewater contaminated by water washing after chemical conversion treatment of metal is treated by providing a neutralization treatment step and a filtration step, the filter cake is discharged out of the system, and the filtrate is reused as washing water after degreasing. There is an example.

  In this example, there is further proposed a chemical conversion treatment line in which waste water after washing with fresh water is reused for washing after chemical conversion treatment with a concentrating device using an evaporation method. In this chemical conversion treatment line, contaminated washing wastewater is not discharged out of the system, and water can be saved (Patent Document 1).

  In addition, when metal surface treatment is performed on a metal molding using a chemical solution, the first flush water in the washing step is taken out, and then treated with a reverse osmosis membrane to recover the chemical component. There is a way. This method is characterized in that, prior to the reverse osmosis membrane treatment, the taken out washing water is filtered by a belt-like filter filtration device.

  In this method, when a reverse osmosis membrane is used in the treatment of a phosphate treatment solution or the like, an active ingredient is to be efficiently recovered by passing it in advance through a strip filter device (Patent Document 2).

  Further, in the invention related to the closed type multi-stage treatment line, the phosphate film chemical conversion treatment process is provided with a multi-stage counter-current water washing process, and the contaminated washing water is treated by a reverse osmosis device, and the contaminated water is discharged outside the line. It is disclosed that water and a chemical solution are separated and reused without being taken out (Patent Document 3).

  Further, in Patent Document 4, in the treatment method of discharged water in the washing step after the phosphate chemical conversion treatment, a large number of anion exchange membranes and cation exchange membranes are alternately arranged between the anion and the anode immersed in the washing discharge water. In addition, a method is disclosed in which a DC current is applied thereto to separate and reuse the washed discharged water into a concentrated solution and high-quality water using an ion exchange membrane electrodialysis layer.

  Further, Patent Document 5 discloses a chemical conversion treatment process including a chemical conversion treatment process for subjecting a chemical treatment object and a one or more water washing process for subjecting the chemical treatment object to a chemical treatment treatment with a chemical conversion treatment tank. A mixed liquid obtained by mixing a part of the stored chemical conversion treatment liquid and a part of the washing water stored in the water washing tank is dialyzed with a filter to separate into a concentrated liquid and a permeated liquid, and the resulting concentrated liquid is obtained. There is disclosed a coating pretreatment method characterized by feeding a chemical conversion treatment tank and sending the obtained permeate to a washing tank. In this invention, the washing water after chemical conversion treatment can be reused as a chemical conversion treatment liquid and flush water without discharging out of the system, thereby solving environmental problems.

  By the way, in the water washing step of the chemical conversion treatment liquid, a so-called countercurrent multi-stage water washing method is employed in which a water washing tank is formed in a multistage structure in order to save a large amount of water to be used. In such a countercurrent multi-stage flushing method, when replenishing flush water, supply flush water to the final tank, and between adjacent flush tanks, flush waste water overflowed from the latter tank is transferred to the previous tank. It is made to flow in sequentially.

  The washing waste water in the front washing tank in the counter-current multi-stage washing is fed upstream from the final washing tank, so the dissolved components after washing contain a lot of hydrochlorides, nitrates, etc. It is. Since these components are different from the components of the chemical conversion liquid, they cannot be returned to the chemical conversion tank, and must be discarded after being treated as overflow water in the wastewater treatment process outside the system.

  Patent Document 6 separates a concentrated solution containing active ingredients such as zinc and nickel heavy metals, phosphoric acid and fluorine, which are effective components of chemical conversion treatment liquid, and a permeate containing unnecessary components such as nitric acid, ammonium and sodium ions. A pressure dialysis method using a pressure dialysis machine is described.

  This pressure dialysis machine uses a spiral ion exchange membrane, and feeds the waste water from chemical conversion treatment water at dialysis pressure and separates it into permeate and concentrate, but the permeate contains nitric acid, ammonium and sodium, which are unnecessary components. Since it contains ions and the like, it is disclosed to further separate and discard them through an ion exchanger.

Japanese Patent Laid-Open No. 50-153455 JP 2002-85942 A JP 54-155135 A Japanese Patent Laid-Open No. 54-158061 JP 2002-102788 A JP 2002-59162 A

  The conventional countercurrent multi-stage flushing system is a system that supplies fresh water to the final flush tank and cascades flush waste water to the previous flush tank. The amount increased, and the costs of evaporating and concentrating devices, reverse osmosis devices, exchange membrane electrodialyzers, and the like were problematic (Patent Document 1, Patent Document 3, Patent Document 4).

  Further, even in the method of treating only the first stage of washing water in the washing process proposed in Patent Document 2, the chemical concentration in the first washing tank is in a 10-fold dilution state of the chemical concentration used for chemical conversion treatment. In addition, since the washing water supply amount is set, the washing waste water cannot be directly introduced into the bonder treatment tank, and it is necessary to recover the chemical component at a high concentration by using a band filter filtration device and a reverse osmosis membrane. Yes.

  As a method for concentrating the washing water, a method using a nanofilter membrane, a reverse osmosis membrane (RO membrane) or a pressure dialysis membrane can be considered. Nanofilter membranes, reverse osmosis membranes and pressure dialysis membranes have the effect of removing some of the chemical conversion liquid components (especially unnecessary accumulation components). It is possible to return to the liquid.

  However, in a closed multistage processing line, in addition to these problems, the water balance problem must be solved. As for the chemical conversion treatment liquid, the carry-in of the liquid (for example, surface adjustment liquid) of the previous process by the work (object to be processed) and the carry-out of the chemical conversion treatment liquid by the work are balanced at a constant volume. However, when an energy-saving (low-temperature) chemical treatment chemical is used, evaporation of the chemical conversion solution can hardly be calculated, and a concentrated solution (washed water concentrate) obtained using a nanofilter membrane or a pressure dialysis membrane can be used. If it uses as a chemical conversion liquid, the quantity of a chemical conversion liquid will increase by that much, and the problem that a chemical conversion tank will overflow will arise. In order to solve this problem, it is necessary to evaporate the chemical conversion treatment liquid by the amount of the washing water concentrate to be supplied, which is against the demand for energy saving and is not rational.

  Moreover, in order to increase the concentration of low-concentration flush water, it is necessary to increase the burden on the filter membrane, but this leads to an increase in the size and cost of the device and also causes problems such as clogging. There is a problem that affects the reliability of the entire apparatus including the filter.

  As a method for solving these problems, a liquid mixture is prepared by mixing a part of the chemical conversion treatment liquid contained in the chemical conversion treatment tank and a part of the washing water contained in the water washing tank, and filtering the liquid mixture. The total circulation type closed, characterized in that the concentrate is separated into a concentrate and a permeate, and the resulting concentrate is sent to a chemical conversion treatment tank, and the resulting permeate is sent to a water washing tank. A method has also been proposed. However, even if the dialysis treatment apparatus can be miniaturized by this method, the use of the dialysis treatment apparatus remains unchanged, and the problem of cost increase cannot be solved (Patent Document 5).

  In addition, it is applicable to a so-called closed system that prevents the waste water from chemical conversion treatment water from being discharged out of the system using a countercurrent multi-stage water washing device. Unnecessary components accumulated when the water is concentrated (nitric acid, ammonium, sodium ions, etc.) ) Is proposed in Patent Document 6, but this method also uses a pressure dialysis treatment apparatus, and thus cannot solve the problem of cost increase.

  In view of the above-mentioned problems, the present invention makes it possible to save the washing water and the processing liquid for forming the phosphate film necessary for the bond processing of the steel sheet without providing a large-scale equipment and reduce the running cost. The purpose is to be able to.

In the present invention, a bond processing liquid recovery washing tank for recovering the bond processing liquid in the form of washing waste water is interposed between the bond processing tank for forming the phosphate film and the water washing tank. In addition, the recovered bonder treatment liquid (washing wastewater) is directly returned to the bonder circulation tank without being passed through a waste liquid treatment device such as an evaporation concentrator, a reverse osmosis device, or an exchange membrane electrodialyzer. .
In the preferred method for reusing waste water for washing, the temperature of the waste washing liquid in the treatment liquid recovery water washing tank is set to 60 ° C. or lower, or the bond solution dilution ratio of the cleaning waste liquid is maintained to 30% or lower. is important.
By maintaining the cleaning waste liquid within the above range, the cleaning waste liquid can be efficiently recovered without adversely affecting the quality of the bonded steel sheet as a product.

According to the present invention, the treatment liquid recovery washing tank is interposed between the bonder treatment tank and the water washing tank, the washing water obtained by washing the steel sheet is collected, and the recovered washing water is washed with the treatment liquid collection water washing. A treatment liquid recovery tank to be supplied to the tank is provided, and the cleaning water recovered in the treatment liquid recovery tank is returned to the bonder solution circulation tank as untreated water as makeup water. In the (treatment) line, the phosphoric acid treatment liquid component contained in the washing waste liquid can be recovered by a simple method. In addition, by reusing washing water, fresh water supplied from outside the system to the bondage treatment line is reduced. As a result, environmental problems and effective use of resources can be achieved, which can contribute to environmental conservation and can reduce the disposal cost required for the disposal of the bonder waste liquid.
In addition, since a bonder processing line can be configured without using a condensing device such as an evaporator or a separation device such as an osmosis membrane, the investment amount of equipment for recovering the phosphoric acid processing liquid component contained in the washing waste liquid can be reduced. Can be suppressed.

(First embodiment)
Hereinafter, a first embodiment of a steel plate bonder according to the present invention and a reuse method of washing wastewater in the bonder will be described with reference to the drawings.
A feature of the steel plate bonder of the first embodiment and the reuse method of the washing wastewater in the bonder is that a part of the wastewater in the treatment liquid recovery tank 6 is returned to the bonder solution circulation tank 5 untreated. It is in. The term “untreated” as used herein means that a special process involving a change in components such as a concentration process and a precipitation coagulation process is not performed, and simple filtration and heat treatment are treated as untreated.

  FIG. 1 is a block diagram showing an overall configuration of a steel plate bonder processing apparatus according to the present embodiment. In FIG. 1, 1 is a bonder pretreatment section, 2 is a bonder treatment tank, 3 is a washing tank for recovering treatment liquid, and 4 is a washing tank.

  Reference numeral 5 represents a bond solution circulation tank, 6 represents a treatment liquid recovery tank, 7 represents a fresh water tank, 8 represents a buffer tank, 9 represents a waste liquid treatment center, and 10 represents a bath concentration analysis and control system. In the present embodiment, the bath concentration analysis and control system 10 includes a bath concentration analyzer 11, a control device 12, a TA replenisher storage tank 13, an FA adjustment liquid storage tank 14, a first pump P1, a second pump P2, It is comprised by 3rd pump P3, 4th pump P4, etc.

  The treatment tank and the treatment liquid collection tank 6 of the treatment liquid collection washing tank 3 are connected by a return pipe 161, and the washing waste liquid is collected in the treatment liquid collection tank 6. The treatment liquid recovery tank 6 and the spray nozzle 20 provided in the treatment liquid recovery water washing tank 3 are connected by a washing water supply pipe 162, and the water washing recovered in the treatment liquid recovery tank 6 is performed. Waste liquid is sprayed on the front and back surfaces of the zinc phosphate-plated steel sheet 200 from the spray nozzle 20 of the treatment liquid recovery rinsing tank 3 by the discharge pressure of the fifth pump P5.

  In the present embodiment, the washing waste liquid in the washing tank 4 is discharged to the waste liquid treatment center 9. As a result, as will be described later, inconvenience does not occur even if the washing waste liquid of the treatment liquid recovery washing tank 3 is returned to the bonder solution circulation tank 5 and used. In the waste liquid treatment center 9, neutralization treatment and sludge treatment are performed to separate sludge and moisture.

  The bonder pretreatment section 1 is an important section for good bond processing. That is, phosphating is a kind of corrosion reaction, and precipitation of heavy metal tertiary phosphate is a basic reaction. In order to produce the chemical conversion film as the corrosion product uniformly and densely on the metal surface, it is necessary to cause many corrosion reactions. For this purpose, crystal nuclei that are the starting points for crystal formation may be formed densely on the surface of the steel sheet. The treatment for generating the crystal nuclei uniformly and densely on the surface of the steel sheet is the role of the pretreatment.

  The purpose of the chemical conversion treatment performed in this embodiment is to form an oxide film or inorganic salt film (a kind of corrosion product) chemically on the steel sheet using a solution, The purpose is to create a coating film for coating.

  In the bonder pretreatment section 1, ringer rolls 21 are provided on the entrance side and the exit side of the treatment tank. Further, a spray nozzle 20 for spraying the pretreatment agent onto the galvanized steel sheet 110 in the treatment tank is provided. In the present embodiment, disodium phosphate (50 to 55%), sodium pyrophosphate (20 to 25%), sodium hydrogen carbonate (5 to 10%) are used as components of the pretreatment agent (Ti chemical colloidal system). ), A titanium compound (1-5%), and monosodium phosphate (1-5%).

  The configuration of the bonder treatment tank 2 is the same as that of the bonder pretreatment section 1. In the bonder treatment tank 2, the bonder treatment liquid is sprayed from the spray nozzle 20 onto the galvanized steel sheet 110, so A phosphate film is formed on top.

  The bonder treatment liquid sprayed from the spray nozzle 20 onto the galvanized steel sheet 110 is accommodated in the bonder solution circulation tank 5. The bonder treatment liquid is a treatment liquid composed of a plurality of components necessary for performing a phosphate chemical conversion treatment for forming a bonde film on the surface of a galvanized steel sheet. The treatment liquid in the bonder solution circulation tank 5 includes, for example, a specific amount and a specific ratio of Mg nitrate: 20 to 25%, Ni nitrate: 5 to 10%, Phosphoric acid: 1 to 5%, Ni phosphate: 1 to 5%, hydrogen fluoride: less than 0.1%, hydrofluoric acid: less than 0.1%, the rest is water treatment liquid, and phosphates corresponding to galvanized steel sheet 110 and usage environment etc. The configuration of the treatment liquid and its component concentration are adjusted appropriately.

  As will be described later, in the present embodiment, the bonder bath concentration adjustment in the bonder solution circulation tank 5 is automatically performed based on the following concept. In addition to automatic measurement and adjustment, the concentration of TA, FA, Zn, Ni, and Mg is confirmed by off-line analysis twice / number.

Next, the material balance of the bonde washing waste liquid circulation system will be described with reference to FIG.
(1) Treatment liquid balance in the bonder treatment tank circulation system qTA: TA replenisher replenishment quantity qFA: FA adjustment liquid input quantity qY: Take-out quantity from bonder treatment tank qL1: Evaporation loss qW: Treatment liquid recovery quantity qB1: Overflow amount

qTA + qFA + qW = qY + qL1 + qB1 ---------------- 1 formula

(2) Treatment liquid balance of treatment liquid recovery washing tank system qX: Replenishment quantity of fresh water qY: Inflow quantity from bonder treatment tank qL2: Evaporation loss qZ: Amount taken out to washing tank qW: Delivery quantity of treatment liquid qB2: Overflow amount

qX + qY = qZ + qW + qL2 + qB2 ------------------- 2 formulas

  Since the purpose of the present application is to reuse as much as possible without discharging the bonder treatment liquid outside the system, the overflow amount (qB1, qB2) is set to zero. In order to make qB2 zero, an operation is performed to control the level of the treatment liquid recovery tank to return the excess amount to the entire bonder solution circulation tank.

Assuming that the evaporation loss (qL1, qL2) is constant, Equation 1 and Equation 2 are

qTA + qFA + qW = qY + K (const) --------------------------------- 3 qq + qY = qZ + qW + K (const) ----------------- --4 formulas

(3) Since the same type of ringer roll is used on the inlet / outlet side of the treatment liquid recovery washing tank, the amount of liquid adhering to and adhering to the steel sheet is almost the same, so if qY = qZ, 3 Formula 4 is

qTA + qFA + qW = qZ + K (const) ------------------ 5 formula qX = qW + K (const) ----------------- -------------- 6 formula

(4) From formulas 5 and 6,

qTA + qFA + qX = qZ + K (const) ------------------- 7

  Therefore, the treatment liquid balance of the entire system may be controlled by controlling the supply amount of “qTA + qFA + qX” following the amount of change (qZ) taken out from the treatment liquid recovery washing tank to the washing tank. That is, the material balance is simplified and the control is simplified by returning the entire amount of the recovered liquid in the processing liquid recovery tank directly to the bonder circulation tank.

(5) Balance of each component of phosphating solution The amount of bonde film formed on the surface of the steel sheet depends on the component concentration of the phosphating solution contained in the bonder tank, Change.
In the present embodiment, the idea that the balance of mass balance of a plurality of components constituting the phosphoric acid treatment liquid in the bonder treatment tank can be stably maintained even in the bonder treatment facility with the treatment liquid recovery washing tank added. To do.

  In the bonder treatment solution, a FA solution generally composed of a 75% phosphoric acid solution and a TA solution mainly containing phosphoric acid and containing nickel nitrate, hydrofluoric acid, magnesium and the like are mixed. When the balance of the components of the phosphating solution is calculated using the above-described solution balance formula (formula 7), the result is as follows.

Balance of FA solution.
P1 * qTA + P2 * qFA = P3 * qZ + R + K (const) ---------------------------------------- (P1, P2, P3 are phosphoric acid concentrations in each solution, R is reaction precipitation on the steel sheet surface) Amount)
Balance of TA solution.
F1 * qTA = F3 * qZ + R + K (const) ---------------------- 9 Concentration, R is the amount of reaction deposited on the steel sheet surface)

(6) About qZ and R qZ (the amount taken out from the treatment liquid recovery rinsing tank to the rinsing tank) and R (reaction precipitation amount) on the right side of the above-mentioned formulas 8 and 9 are the processing amount, that is, the line within the unit time of the steel sheet. Depends on speed. Therefore, if the deviation correction according to the line speed is performed based on the formulas 8 and 9, the TA and FA densities can be adjusted.

The concept of bath concentration automatic adjustment in the present embodiment will be described below.
First, the TA concentration and FA concentration are measured using the bath concentration analyzer 11 (online analyzer). Then, based on the measurement result, the TA replenishing liquid and the FA adjusting liquid input amount are automatically adjusted.
(1) TA adjustment: TA replenishment solution and washing waste solution are continuously added to adjust TA concentration.
TA replenisher input amount = (1 + ΔTA deviation) * A * plate width * plate thickness * line speed
Washing waste liquid input amount = (1 + ΔTA deviation) * B * plate width * plate thickness * line speed. However, ΔTA deviation means a difference in TA concentration between the target value and the analysis value.

(2) FA adjustment: The FA density is adjusted when the threshold value is exceeded.
FA adjustment liquid input amount = ΔFA deviation * C * tank level However, ΔFA deviation means a difference in FA concentration between the target value and the analysis value.

(3) Tank level adjustment: TA replenisher and washing waste liquid are charged at a constant ratio.
(TA replenisher + washing waste liquid) Input amount = Δ tank level deviation * D
However, the Δ tank level deviation is the difference between the target level and the actual level.
In the above (1) to (3), A, B, C, and D are constants (the operator may change with reference to the analysis result).

FIG. 2 is a view schematically showing a cross section of the steel plate in a state where a bondage film is formed on the surface of the galvanized steel plate 110. For example, in the phosphating apparatus using a phosphate treatment solution containing zinc ions, phosphate ions, magnesium ions, nitrate ions, nickel ions, and the like, the surface of the ground iron (Fe) layer 210 is placed. A predetermined amount of the zinc layer 220 is formed by electroplating, and a bond film 230 composed of phosphoric acid, zinc, and magnesium is further formed to manufacture the zinc phosphate-plated steel sheet 200. Specifically, the bond film 230 is, for example, Zn ₃ (PO ₄ ) ₂ .7H ₂ O, Zn ₂ .Mg (PO ₄ ) ₂ .7H ₂ O.

  In the bond processing tank, a plurality of spray nozzles 20 are disposed in order to form a bond film 230 having a predetermined thickness on the galvanized steel sheet 110 carried into the bond processing tank. The spray nozzle 20 and the bonder solution circulation tank 5 are connected by a phosphating solution supply pipe 150.

  The phosphating solution supply pipe 150 is provided with a first pump P1, and the phosphating solution contained in the bonder solution circulation tank 5 is received by the first pump P1. The galvanized steel sheet 110 is sprayed from the plurality of spray nozzles 20 by being pumped up. The plurality of spray nozzles 20, the phosphate treatment liquid supply pipe 150, and the first pump P1 constitute a phosphate treatment liquid spraying means.

  The phosphating solution sprayed on the galvanized steel sheet 110 is returned to the bonder solution circulation tank 5 through a return pipe 151 connected to the lower part of the bonder spray tank. In addition, the spray control apparatus which is not shown in figure controls the spraying time and spraying amount of the said phosphate process liquid.

  In the steel plate bonder of the present embodiment, the TA replenisher storage tank 13, the FA adjusting liquid storage tank 14, and the washing waste liquid are used to adjust the concentration of the phosphate processing liquid in the bonder solution circulation tank 5. A buffer tank 8 is provided, and the components constituting the phosphate treatment liquid in the bonder solution circulation tank 5 are adjusted so as to have a predetermined concentration.

  The TA replenishing liquid storage tank 13 contains a mixed solution (hereinafter also referred to as TA replenishing liquid) mainly containing phosphoric acid, nickel nitrate, hydrofluoric acid, and a small amount of magnesium. : Total Acid, unit: points). Here, the total acidity is obtained by taking 10 mL of a chemical conversion treatment solution using a whole pipette, titrating with 0.1 N sodium hydroxide aqueous solution using phenolphthalein as an indicator until the pH becomes 8.3. This is the volume (mL) of the required aqueous sodium hydroxide solution.

  The FA adjusting solution storage tank 14 contains a 75% phosphoric acid solution (hereinafter also referred to as FA stock solution) and is used for adjusting the free acidity (FA: Free Acid, unit: point). Here, free acidity means that 10 mL of a chemical conversion treatment solution is collected using a whole pipette, titrated with 0.1 N sodium hydroxide aqueous solution using bromophenol blue as an indicator, until pH becomes 3.8. This is the volume (mL) of the required aqueous sodium hydroxide solution.

  The free acidity (FA) greatly affects the formation density of zinc phosphate crystal nuclei, which is the initial reaction on the surface of the galvanized steel sheet, and the film deposition rate in the reaction process when performing the phosphorylation treatment. It is a component that determines the coating amount. Free acidity (FA) decreases by these reactions, but the amount of change differs depending on the steel sheet surface properties and the concentration of sludge contained in the phosphating solution. The FA adjustment liquid stored in the FA adjustment liquid storage tank 14 is a liquid whose main purpose is to increase the concentration of the free acidity (FA).

The total acidity (TA) is a factor obtained by adding the primary zinc phosphate concentration (H2PO4 ⁻ ) and the free acidity (FA), and is a component that is a source of phosphate ions in the zinc phosphate coating (Zn3PO4). Used as an index for managing the concentration of primary zinc phosphate. The TA replenisher stored in the TA replenisher storage tank 13 is a liquid mixed for the purpose of constantly replenishing zinc phosphate, hydrofluoric acid, nickel ions and other trace elements consumed by film formation. It is.

The adjustment of the free acidity, the total acidity, and the acid ratio in the present embodiment is not particularly limited, and the composition and concentration of the phosphating solution are appropriately determined depending on the use of the zinc phosphate-plated steel sheet 200. Is.
In order to increase the points of total acidity and free acidity, it is possible to increase the acid concentration by increasing the ratio of acids such as phosphoric acid and nitric acid. On the contrary, in order to lower the points of total acidity and free acidity, although not particularly limited, for example, diluting with an aqueous sodium hydroxide solution or water can be mentioned. When using an aqueous sodium hydroxide solution, it is desirable to use a solution diluted to about 0.01 N because zinc phosphate sludge is likely to be generated by a local neutralization reaction.

  The washing waste liquid buffer tank 8 is filled with the washing waste liquid returned from the primary washing circulation tank 6 untreated. Since the phosphating solution in the bonder solution circulation tank 5 is an aqueous solution, the water evaporates while circulating between the bonder solution circulation tank 5 and the bonder treatment tank. I have prepared it.

  Note that the number of these liquid tanks is not necessarily limited to three, like the TA replenishing liquid storage tank 13, the FA adjustment liquid storage tank 14, and the washing waste liquid buffer tank 8 described above. Further, the water stored in the washing waste liquid buffer tank 8 may be stored together with the mixed solution in the TA replenishing liquid storage tank 13 to constitute a total of two liquid tanks.

  The bath concentration analyzer 11 is an analyzer for analyzing the component concentration of the treatment liquid in the bonder solution circulation tank 5. Specifically, the pH of the processing solution reaches a specific value by detecting the pH fluctuation in the solution when a predetermined solution (NaOH) is sequentially dropped into a certain amount of processing solution using a weight burette. The concentration of the treatment liquid is determined from the amount of the predetermined solution (NaOH) required up to the time point. By setting in advance the time interval at which the concentration analysis process is started, the bath concentration analyzer 11 automatically analyzes the component concentration of the treatment liquid at each set time.

  Based on the analysis result of the component concentration of the treatment liquid analyzed by the bath concentration analyzer 11, the control device 12 specifies a component that needs to be replenished with the phosphate treatment liquid in the bonder solution circulation tank 5. Or calculate the replenishment amount.

  Further, the control device 12 is configured so that the calculated amount of replenisher is replenished into the bonder solution circulation tank 5 from predetermined replenisher tanks (replenisher tanks containing the specified components) 13, 14, 8. Outputs a control command for the operation of the pumps P2 to P4 attached to the corresponding replenisher tank.

  In the zinc phosphate-plated steel sheet 200 on which the phosphate coating is formed on the front and back surfaces by the chemical conversion treatment line as described above, the phosphate treatment liquid adhering to the surface is washed with water in the next washing step. The steel plate bonder of the present embodiment is designed to collect as much of the phosphating liquid taken out from the bonder tank 2 to the outside as much as possible.

  That is, as shown in FIG. 1, the water washing step is divided into a treatment liquid recovery water washing tank 3 and a water washing tank 4, and the treatment liquid recovery water washing tank 3 mainly recovers the phosphate treatment liquid, Full-fledged water washing is performed in the tank 4 so as to stop the bonding process accompanied by the corrosion reaction on the surface of the zinc phosphate-plated steel sheet 200.

  In order to achieve such an object, the washing water used in the treatment liquid recovery rinsing tank 3 is returned to the treatment liquid collection tank 6 via the return pipe 161 and the inside of the treatment liquid collection tank 6 is washed. Water is supplied to the front and back surfaces of the zinc phosphate-plated steel sheet 200 from the spray nozzle 20 disposed in the treatment liquid recovery washing tank 3 using a circulation pump P5 provided in the washing water supply pipe 162. I try to spray.

  By wiping the phosphating solution adhering to the front and back surfaces of the zinc phosphate-plated steel sheet 200 with the ringer roll 21 disposed on the outlet side of the bond section 2, the phosphating solution taken out to the outside can be as much as possible. I try to reduce it. However, since the bond processing is performed at a high speed, the bond processing tank 2 leaves the surface of the zinc phosphate-plated steel sheet 200 with a considerable amount of the phosphate processing solution attached thereto.

  Therefore, as described above, in the present embodiment, the phosphating solution is recovered in the primary rinsing water by recovering and circulating the cleaning water used at the beginning of the rinsing process. The primary washing water whose concentration of the phosphating solution is improved by the recovery is returned to the washing waste liquid buffer tank 8 and returned from the washing waste liquid buffer tank 8 to the bonder solution circulation tank 5. In the present embodiment, “5 liters / minute” of washing water is returned from the treatment liquid recovery tank 6 to the washing waste liquid buffer tank 8. Further, “80 liters / minute” of cleaning water is supplied from the processing liquid recovery tank 6 to the processing liquid recovery water washing tank 3. It should be noted that “300 liters / min” of fresh water is supplied from the fresh water tank 7 to the washing tank 4.

  As described above, by cascade-connecting the washing tank 3 for collecting the treatment liquid for collecting the phosphate treatment liquid between the washing tank 4 for performing full-scale washing and the bonder treatment tank 2, In the steel sheet bonder processing apparatus of the embodiment, the amount of bonder chemicals used could be greatly reduced. An example is shown in FIG. In the case of this example, the bonder chemical unit can be reduced to 52% by changing the equipment so as to recover the phosphating solution by providing the rinsing tank 3 for recovering the processing solution.

  FIG. 4 shows an example of the dilution rate transition of the washing waste liquid in the treatment liquid recovery washing tank during the chemical conversion treatment. FIG. 4A shows that the dilution ratio of the primary flushing water bonder solution reaches 25% after passing through about 40 hours after the start of application of the total amount of liquid recovery. In FIG. 4A, black circles indicate the results of ICP analysis, and solid lines indicate the results of obtaining the bonder solution ratio by flow measurement.

  FIG. 4B shows a state in which the bond solution dilution ratio of the waste water for washing in the treatment liquid recovery washing tank is maintained at about 25% and a steady operation is performed. In FIG. 4B, the black triangle mark indicates the ICP analysis result, and the solid line indicates the result of obtaining the bonder solution ratio by flow rate measurement.

FIG. 5 is a characteristic diagram showing the relationship between the line speed and the amount taken out from the bonder line tank.
FIG. 5 (a) shows the relationship between the line speed and the amount taken out per unit width when the treatment liquid recovery washing tank 3 is provided, and FIG. 5 (b) does not provide the treatment liquid recovery washing tank 3. The relationship between the line speed and the amount taken out per unit width is shown. As is clear from these characteristic diagrams, the amount of the phosphate treatment liquid taken out can be greatly reduced by providing the treatment liquid recovery rinsing tank 3.

  In order to reduce the carry-out amount of the phosphate treatment liquid, it is preferable that the tank length of the treatment liquid recovery washing tank is 2 m or less. The treatment liquid recovery washing tank has ringer rolls for liquid squeezing on the inlet and outlet sides of the steel sheet.If the tank length is shortened and the interval between the inlet and outlet ringer rolls is shortened, the shape forcing effect of the steel sheet is reduced. The liquid squeezing performance is dramatically improved.

  FIG. 6 is a characteristic diagram showing a result of simulating a change in the bond solution dilution ratio in the collected treatment liquid with the actual coil passage size using the relationship of the amount taken out. As shown in FIG. 6, it can be seen that the bond solution dilution rate is saturated at about 25%.

  The bond solution dilution ratio is determined mainly by the balance between the amount of the phosphate treatment liquid taken out from the bond processing tank to the washing tank for recovering the processing liquid and the amount of fresh water. If the bond dilution ratio exceeds 30%, as shown in FIG. 8, the bond adhesion amount is affected, so the bond dilution ratio must be lowered. In order to decrease the bond dilution ratio, a method is adopted in which a part of the recovered liquid in the processing liquid recovery tank is taken out of the system as waste liquid and the amount of fresh water is increased.

Next, an example of performing online concentration control for the FA adjustment liquid and the TA replenishment liquid will be described with reference to the flowchart of FIG.
As shown in FIG. 7, first, when the galvanized steel sheet 110 is carried into the bonder treatment spray tank (step S300), spraying of the treatment liquid onto the galvanized steel sheet 110 is started (step S301). It should be noted that the order of steps S300 and S301 is reversed, and after the spraying of the treatment liquid is started in advance (step S301), the galvanized steel sheet is carried into the bond spray tank (step S300), and the operation control is performed. You may be made to do.

Next, it progresses to step S3011, and the total acidity (TA) of the bonder waste liquid in the washing tank for process liquid collection | recovery is measured every predetermined time (for example, 3 hours), and a bonder solution dilution rate is calculated.
Then, in step S3012, it is determined whether the bond solution dilution rate is 30% or less. If the bond solution dilution ratio is 30% or less as a result of this determination, the process proceeds to the next step S302. If the bond solution dilution rate exceeds 30% as a result of the determination in step S3012, the process proceeds to step S3013 to perform a waste liquid concentration adjustment process. This is performed by maintaining a constant liquid level in the treatment liquid recovery tank and overflowing a part of the recovered waste liquid in the tank by additionally supplying fresh water.

  In the online concentration control of the present embodiment, it is monitored whether or not a predetermined time (for example, 15 minutes) has elapsed for spraying of the processing liquid described above (step S302), and bath concentration analysis is performed when the predetermined time has elapsed. The total acidity (TA) and free acidity (FA) are measured by the apparatus 11 (steps S303 and S304).

  By these measurements, the measured values of the FA component concentration and TA component concentration of the treatment liquid circulating between the bonder solution circulation tank 5 and the bonder treatment spray tank are output as analysis results by the bath concentration analyzer 11.

  Next, the FA and TA component concentration values (current FA and TA component concentration values) output every 15 minutes from the bath concentration analyzer 11 are input to the control device 12, and the input current values are input. The FA component and TA component concentration values are compared with the FA component and TA component concentration values (target FA component and TA component concentration values) appropriate for forming the bond film 230 having a predetermined thickness.

  This comparison process is performed in the following step S3041. Information on the target phosphoric acid treatment adhesion amount, plate thickness, plate width, and line speed of a steel plate to be processed (galvanized steel plate) is captured.

  The algebraic product (W × LS) of the plate width W of the steel plate and the traveling speed LS of the steel plate corresponds to the bond coating treatment area per unit time. The amount of FA solution and TA solution required can be predicted from this reaction area (W × LS) and the target phosphoric acid treatment adhesion amount. In addition, since the plate thickness affects the amount of liquid accompanying the ringer roll, it becomes important information together with the line speed.

  Next, proceeding to step S3042, the control device 12 calculates how much the current FA component and TA component density values show an increase or decrease with respect to the target FA component and TA component density values. .

  If the calculated increase / decrease in the concentration value of each component exceeds a predetermined fluctuation range that can be regarded as a constant concentration value, the amount of phosphate treatment liquid present in the present bond solution circulation tank 5 and the bond treatment spray Considering the amount of phosphating solution used for spraying in the tank and the amount of phosphating solution being circulated by pump P1, the current concentrations of FA and TA components are set to the target concentration values. In order to become, the amount of replenishment required is calculated by the control device 12 for each of the TA component, the FA component, and water (steps S305 and S306).

  Next, in order to feed the calculated replenishment amount of replenishment liquid from the FA adjustment liquid storage tank 14 and the TA replenishment liquid storage tank 13 into the bonder solution circulation tank 5, the control device 12 includes the FA adjustment liquid storage tank. 14 and a third pump P3 provided in a liquid supply pipe connecting between the bonder solution circulation tank 5 and between the TA supply solution storage tank 13 and the bonder solution circulation tank 5. The operation time of the second pump P2 interposed in the liquid replenishing pipe connected to is set (step S307).

When the operation control command for the second pump P2 and the third pump P3 is issued from the control device 12, the TA replenishing liquid storage tank 13 and the FA adjustment liquid storage tank 14 are transferred to the bonder solution circulation tank 5. Then, the actual replenisher is supplied (step S308).
Next, in step S309, it is determined whether or not the process is finished. When the process is continued, the process returns to step S302 and the above-described process is repeated.

FIG. 8 is a characteristic diagram showing a result of investigating the influence on the chemical conversion treatment product by changing the bond solution dilution rate in the treatment liquid recovery tank.
The bond solution dilution ratio indicates a mixing ratio of the chemical conversion treatment solution contained in the washing waste liquid in the treatment liquid recovery tank, and is defined as follows. When TA (total acidity) of the chemical conversion treatment solution in the bonder treatment tank is A, TA (total acidity) of the chemical conversion treatment solution in the washing tank for recovering the treatment liquid is B,
Bonde solution dilution ratio (%) = B / A × 100.
Therefore, in the washing waste liquid having a bond solution dilution ratio of 30%, the bond solution is diluted to a concentration of 30%.

  As shown in FIG. 8, the inventors completely stopped the chemical conversion reaction on the steel sheet when the bond solution dilution rate of the treatment liquid recovery washing tank was 30% or more and the liquid temperature at that time was 60 ° C. or more. It was confirmed that the process progressed unevenly. In such a state, the surface cleanliness of the product deteriorates, so the bond solution dilution ratio may not be too high. The upper limit of the bond solution dilution ratio varies depending on the required quality of the product, the liquid composition of the bond solution, etc., but in normal chemical conversion treatment, it was confirmed that the liquid temperature is preferably 30% or less and the liquid temperature is preferably 60 ° C. or less. .

It is a block diagram which shows embodiment of the bonder processing apparatus of the steel plate of this invention, and shows the structure of the principal part. It is the figure which showed typically the cross section of the steel plate of the state in which the bonder film was formed in the surface of a galvanized steel plate. It is a characteristic view which shows the example which the usage-amount of bonde chemical | medical agent decreased. It is a characteristic view which shows the relationship between the bonder solution dilution rate and the plate passing speed. It is a characteristic view which shows the relationship between a line speed and the amount of taking out per unit width. It is a characteristic view which shows the relationship between the bond solution dilution rate in collection | recovery process liquid, and plate passing time. It is a flowchart explaining an example which performs on-line density | concentration control which made FA adjustment liquid and TA replenishment liquid object. It is a characteristic view which shows the relationship between a bond solution dilution rate and the amount change of adhesion. It is a figure for demonstrating the material balance of a bond water washing waste liquid circulation system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bonde pretreatment section 2 Bonde treatment tank 3 Washing tank for treatment liquid recovery 4 Washing tank 5 Bonde solution circulation tank 6 Treatment liquid recovery tank 7 Fresh water tank 8 Washing waste liquid buffer tank 9 Wastewater treatment center 10 Bath concentration analysis and control system DESCRIPTION OF SYMBOLS 11 Bath concentration analyzer 12 Control apparatus 13 TA replenisher storage tank 14 FA adjustment liquid storage tank 15 Waste liquid collection | recovery apparatus 20 Spray nozzle 21 Ringer roll 110 Galvanized steel plate 150 Phosphate processing liquid supply piping 151 Return piping 161 Return piping 162 Cleaning Water supply pipe 200 Zinc phosphate plated steel sheet

Claims (11)

A bonder solution circulation tank containing a phosphate film forming treatment liquid for forming a phosphate film, and a phosphate film formed on the steel sheet by the phosphate film formation treatment liquid supplied from the bonder solution circulation tank. In a steel plate bonder treatment apparatus having a bonder treatment tank for forming a water-washing tank for washing a steel sheet on which a phosphate film is formed in the bonder treatment tank,
A treatment tank recovery washing tank interposed between the bonde treatment tank and the washing tank;
In the treatment liquid recovery rinsing tank, there is a treatment liquid recovery tank for recovering the washing water obtained by washing the steel sheet, and circulatingly supplying the recovered washing water to the treatment liquid recovery rinsing tank. A steel plate bonder processing apparatus, wherein a pipe for returning the cleaning water recovered in the processing liquid recovery tank to the bonder solution circulation tank is untreated.   A fresh water supply pipe for replenishing the phosphate film forming treatment liquid taken out from the bond treatment tank and the treatment liquid recovery washing tank and adjusting the components is provided in the treatment liquid collection tank, and the phosphate 2. The steel plate according to claim 1, wherein a supply pipe for a TA replenisher and an FA adjusting liquid for maintaining a constant total acidity and free acidity of the film forming treatment liquid is provided in the bonder solution circulation tank. Bonde processing equipment.   The steel sheet bonder processing apparatus according to claim 1 or 2, wherein the bonder process and the water washing process are performed by a spray device.   The steel plate bonder according to claim 1 or 2, wherein a tank length of the water tank for recovering the treatment liquid is 2 m or less, and ringer rolls are installed at both ends of the pass line of the steel plate. Processing equipment.   Replenishment necessary to balance the amount of inflow liquid that enters the bonder solution circulation tank containing the phosphate film forming treatment liquid and the amount of carry-out liquid that is taken out of the bonder solution circulation tank. The steel plate bonder processing apparatus according to any one of claims 1 to 3, further comprising a concentration control device that calculates a quantity for each component substance and performs replenishment adjustment control of each component liquid.   As an analyzer for analyzing the component concentration of the processing solution for forming a phosphate film accommodated in the above-mentioned bonder solution circulation tank, a predetermined solution is successively dropped into a fixed amount of the phosphate processing solution. It has an automatic neutralization titration device that detects pH fluctuations in the liquid and determines the component concentration of the phosphating solution from the predetermined amount of solution required until the pH is neutralized. The steel sheet bonder processing apparatus according to claim 4. In the reuse method of waste water for washing in a bonder treatment apparatus having a bond treatment tank for forming a phosphate film on a steel sheet and a water washing tank for washing the steel sheet on which the phosphate film is formed in the bonde treatment tank,
A treatment liquid recovery washing tank is interposed between the bonder treatment tank and the water washing tank, and the temperature of the washing water sprayed to wash the steel plate in the treatment liquid collection washing tank is 60 ° C. or less. A method for reusing washing waste water in a bonder treatment apparatus, wherein the recovered washing waste liquid is returned untreated as makeup water to the bonder solution circulation tank.   The washing waste water in the treatment liquid recovery tank is supplied untreated to the solution circulation tank as make-up water for replenishing the phosphate film forming treatment liquid taken out from the bonder treatment tank and the treatment liquid recovery washing tank. In addition, the TA replenisher and the FA adjusting liquid for maintaining the total acidity and free acidity of the phosphate film forming treatment liquid to be constant are supplied to the bonder solution circulation tank to adjust the components. Item 8. A method for reusing washing wastewater in a bonder treatment apparatus according to Item 7.   9. The method for reusing washing waste water in a bonder treatment apparatus according to claim 7 or 8, wherein the bond solution dilution ratio of waste water in the treatment liquid recovery tank is 30% or less.   9. The method for reusing flush wastewater in a bonder treatment apparatus according to claim 7 or 8, wherein the amount of makeup water supplied to the treatment liquid recovery washing tank is determined based on a plate passing speed of the steel plate. 11. The amount of TA replenisher, FA adjustment liquid, and washing waste liquid supplied to the bonder solution circulation tank is determined by calculation based on a material balance in the bonder solution circulation tank. The reuse method of the flush wastewater in the bonde processing apparatus as described in a term.

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