JP2003038983A - Sludge thickening method, thick sludge obtained by this method and sludge thickening equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for selectively thickening a sludge mixture containing ferrous sludge in a phosphate chemical conversion treatment liquid and aluminum-system sludge to high concentrations by the kinds of the metals in the sludge. SOLUTION: This method for thickening the sludge includes a process step (1) of transferring the phosphate chemical conversion treatment liquid containing the ferrous sludge and the aluminum-system sludge in a position of (1/2) H or above when the minimum value (mm) of the liquid level height in a chemical conversion tank of the phosphate chemical conversion treatment liquid is defined as H and a process step (2) of recovering the sludge from the transferred phosphate chemical conversion treatment liquid.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for selectively concentrating sludge from a chemical conversion treatment solution after a phosphate chemical conversion treatment, and more specifically to a method for selectively concentrating aluminum-containing sludge having a small specific gravity. .

[0002]

2. Description of the Related Art Generally, metal moldings for automobiles are used for degreasing treatment to remove oil adhering to the surface and for forming a chemical conversion film in a subsequent chemical conversion treatment. After a series of pre-treatment steps of adjustment treatment and phosphate chemical conversion treatment for improving corrosion resistance and abrasion resistance, electrodeposition coating is performed.

Of these, the phosphate chemical conversion treatment liquid after the phosphate chemical conversion treatment produces sludge derived from various metals such as iron, aluminum, and zinc that compose automobile bodies as a by-product. However, conventionally, sludge containing these various metals has usually been transferred from a chemical conversion treatment tank to a settling tank and separated, and then discharged as a mixture out of the system for landfill disposal.

[0004] It is desired that this sludge be recovered and used without being discarded in view of the recent consideration for the environment, reduction of the waste treatment site, waste treatment cost and the like. As methods for recovering and utilizing sludge, for example, fluxing of fluorine-containing aluminum-based sludge and pigmentation of iron-based sludge have been proposed.

For the purpose of recovering and utilizing the sludge generated in the zinc phosphate chemical conversion treatment, specifically, JP-A-2000-2 is used.
48193 discloses a method for producing a phosphate-containing pigment in which sludge generated in a zinc phosphate chemical conversion treatment step is calcined at 300 to 900 ° C. for 30 to 180 minutes, and JP 2001-048506 A discloses. Sludge generated by the zinc phosphate chemical conversion treatment is dried by a cylindrical dryer to obtain dried sludge, and the dried sludge is added to
A method for producing a phosphate pigment, which comprises firing at 900 ° C. for 10 to 180 minutes, is disclosed. However, a method for separating sludge contained in the zinc phosphate chemical conversion treatment liquid according to the type of metal is not disclosed, and there is a problem in using the above-described recycling method suitable for the type of metal.

[0006]

SUMMARY OF THE INVENTION In view of the above, the present invention is directed to a high concentration of a sludge mixture containing iron-based sludge and aluminum-based sludge in a phosphate chemical conversion treatment solution, depending on the type of metal in the sludge. The purpose is to provide a method.

[0007]

Means for Solving the Problems The present inventors have made it possible to recycle various metals depending on the sludge by selectively concentrating the sludge depending on the type of the metal from which it is derived, and to promote the recovery and utilization of the sludge. As a method of obtaining and selectively concentrating the sludge, a concentration gradient is generated in the chemical conversion treatment tank, and among these, the content rate of the aluminum-based sludge having a relatively small specific gravity as compared with the iron-based sludge is The present invention has been completed by finding that the aluminum-based sludge can be selectively made to have a high concentration by collecting a high upper layer portion. The aluminum-based sludge whose content is selectively increased in this way can be recovered by a simple method such as filtration.

According to the present invention, a phosphate chemical conversion treatment liquid containing iron-based sludge and aluminum-based sludge is treated with a minimum value (m) of the liquid level of the chemical conversion treatment tank of the phosphate chemical conversion treatment liquid.
When m) is H, it includes a step (1) of transferring at a position of (1/2) H or more, and a step (2) of collecting sludge from the transferred phosphate chemical conversion treatment solution. It is a characteristic sludge concentration method.

The above-mentioned phosphate chemical conversion treatment liquid is (1/2) H
In addition to the step (1) of transferring at the above position, the step (3) of transferring from the lower portion of the chemical conversion treatment tank to the recovery tank is preferable. In the step (2) of collecting the sludge, the phosphate chemical conversion treatment liquid is filtered,
The filtrate is returned to the chemical conversion treatment tank, while the sludge is preferably recovered by filtration. More preferably, the filtration is performed with a cloth filter. It is preferable that the chemical conversion treatment tank further has a hopper installed at the bottom thereof. The present invention is also a concentrated sludge obtained by the above-mentioned method for concentrating aluminum-based sludge.

The present invention further comprises a chemical conversion treatment tank (A) containing a phosphate chemical conversion treatment liquid containing iron-based sludge and aluminum-based sludge, and the minimum liquid surface height of the chemical conversion treatment tank (A) ( (mm) is H, a transfer unit (B) installed at a position of (1/2) H or more, and a sludge recovery device (C) connected to the transfer unit (B).
It is also a sludge concentrating device characterized by containing. Further, it is preferable to include a unit (D) for transferring the phosphate chemical conversion treatment liquid from the chemical conversion treatment tank (A) to the recovery tank. Hereinafter, the present invention will be described in detail.

The sludge concentration method of the present invention increases the content of aluminum sludge in a phosphate chemical conversion treatment liquid containing iron sludge and aluminum sludge. The sludge concentration method of the present invention focuses on the fact that there is a difference in the specific gravity of the sludge depending on the type of metal from which the sludge is derived, and that a concentration gradient occurs in the chemical conversion treatment tank, and the specific gravity is iron-based sludge. Compared with, the content of aluminum-based sludge, which is small, is selectively increased. Examples of the aluminum-based sludge include those containing aluminum oxide, cryolite, elpasolite, aluminum nitrate, aluminum phosphate and the like. The equilibrium concentration of the aluminum-based sludge in the phosphate chemical conversion treatment solution depends on the metal composition of the coating object to be subjected to the chemical conversion treatment, but is, for example, 1 to 1.
It may be 000 ppm or the like.

Of the sludges in the phosphate chemical conversion treatment solution, the iron-based sludges include iron oxide, FePO ₄ ,
Examples thereof include those containing nH ₂ O, Fe ₃ (PO ₄ ) ₂ · nH ₂ O, phosphophyllite and the like. The phosphate chemical conversion treatment liquid may further contain zinc-based sludge containing zinc. The equilibrium concentration of the iron-based sludge in the phosphate chemical conversion treatment solution depends on the metal composition of the coating object to be subjected to the chemical conversion treatment, but is, for example, 5 to 5.
It may be 2000 ppm or the like.

The aluminum-based sludge and the iron-based sludge are produced as by-products by subjecting the article to be coated to phosphate chemical conversion treatment. The object to be coated is
It is made of aluminum, iron and / or an alloy thereof, and may optionally contain other metal such as zinc or an alloy thereof. Specific examples of the object to be coated include aluminum and / or aluminum alloys and cold-rolled steel sheets, and if desired, metal bodies such as automobile bodies and their parts whose main objects are galvanized steel sheets. it can. The article to be coated which has been subjected to the phosphate chemical conversion treatment is usually washed with water, but the phosphate chemical conversion treatment liquid may contain the cleaning wastewater.

The above-mentioned phosphate chemical conversion treatment is performed to improve the durability of the metal molding.
It is performed to improve corrosion resistance and abrasion resistance. Formation
Phosphate chemical conversion treatment solution that performs the treatment is usually used.
Zinc phosphate as the main component
Other than zinc,²⁺, Mg²⁺, Co²⁺, Cu²⁺,
Mn²⁺, Ca²⁺, Na⁺ , Fe²⁺, NH_Four ⁺ , H⁺ , A
PO as a nion component_Four ^3- , NO₃ ^- , NO₂ ^- , F
^- , SiF₆ ^2- , ClO ₃ ^- , SO_Four ^2- Etc. are included
Alternatively, a part of the organic acid may be included.

In the sludge concentrating method of the present invention, the phosphate chemical conversion treatment liquid is treated with the minimum value (m) of the liquid level height of the chemical conversion treatment tank.
When m) is H, the step (1) of transferring at a position of (1/2) H or more is added. The chemical conversion treatment tank is generally constantly stirred so that the concentration of the active ingredient of the phosphate chemical conversion treatment solution is uniform, but if the stirring speed is too high, problems such as foaming may occur. To occur,
Adjusted accordingly. In the sludge generated in the phosphate chemical conversion treatment solution, iron-based sludge with a relatively high specific gravity is likely to settle in the chemical conversion treatment tank, while aluminum sludge with a relatively low specific gravity is less likely to settle and the It floats almost uniformly in the treatment tank. In the present invention, sludge containing a small proportion of iron-based sludge in the height from the middle part to the upper part of the chemical conversion treatment tank is collected.

The aluminum sludge settled in the chemical conversion treatment tank is 70% or less of the aluminum based sludge in the chemical conversion treatment liquid, depending on the stirring speed of the chemical conversion treatment tank, the content of aluminum sludge in the sludge, and the like. It is preferable. If it exceeds 70%, the amount of the aluminum-based sludge floating in the upper layer portion in the chemical conversion treatment tank decreases, and the content may not be sufficiently increased. It is preferably 60% or less, and more preferably
That is, it is uniformly suspended in the chemical conversion treatment tank.

The iron-based sludge settled in the chemical conversion treatment tank is preferably 55% or more of the iron-based sludge in the chemical conversion treatment liquid on a mass basis. If it is less than 55%, the floating content in the chemical conversion treatment tank of the iron-based sludge increases,
Separation from the aluminum-based sludge tends to be insufficient. It is preferably at least 60%.

When the minimum value (mm) of the liquid surface height of the chemical conversion treatment tank is H, the transfer from the chemical conversion treatment tank is (1 /
2) It is performed at a position of H or higher. Since the content rate of the aluminum-based sludge having a relatively small specific gravity is high from the middle portion to the upper layer portion of the chemical conversion treatment tank, the chemical conversion treatment tank should be treated at a position above the middle point of the minimum liquid level height of the chemical conversion treatment tank. By collecting the treatment liquid, the content of the aluminum-based sludge having a relatively small specific gravity can be selectively increased. If the export position is less than (1/2) H, the concentration of the iron-based sludge becomes too high, and the selective concentration of the aluminum-based sludge becomes insufficient. It is preferably (3/4) H or more.

The minimum value of the liquid level height of the chemical conversion treatment tank is
If the height of the chemical conversion treatment tank is constant, it means the height of the liquid surface.If the hopper is installed at the bottom of the chemical conversion treatment tank, the height of the equalization treatment tank is uniform. If not, it means that the minimum value of the height of the liquid surface is adopted.

The chemical conversion treatment tank preferably has a hopper in order to promote the sedimentation of iron-based sludge having a relatively high specific gravity and to effectively selectively concentrate the aluminum-based sludge. The hopper is not particularly limited, and for example, one having 1 to 5 hoppers per one of the chemical conversion treatment tanks can be mentioned, and one having a plurality of hoppers is preferable from the viewpoint of increasing the sedimentation amount of the iron-based sludge.

The flow rate for transferring the phosphate chemical conversion treatment solution depends on the volume and shape of the chemical conversion treatment tank, but generally 0.8 to 2% of the chemical conversion treatment solution in the chemical conversion treatment tank per minute.
It is preferable to transfer the chemical conversion treatment liquid having a certain volume. For example, in the case of 100 tons of chemical conversion treatment tank, 800 to 20
About 100 L / min is preferable. If it is less than 0.8%, aluminum-based sludge may also settle, and if it exceeds 2%, iron-based sludge may be transferred without settling. Preferably, it is 0.9 to 1.7% / min based on the volume of the chemical conversion treatment liquid in the chemical conversion treatment tank.

The chemical conversion treatment liquid transferred from the chemical conversion treatment tank contains the aluminum-based sludge and the iron-based sludge that have not settled in the chemical conversion treatment tank. The mass ratio of the aluminum-based sludge to the total sludge in the chemical conversion treatment liquid transferred from the chemical conversion treatment tank is higher than the total chemical conversion treatment liquid in the chemical conversion treatment tank, the chemical conversion treatment liquid in the chemical conversion treatment tank It is preferably 1.1 times or more of the whole. When it is less than 1.1 times, the content rate of the above-mentioned aluminum-based sludge in the entire sludge obtained becomes too low, and the reuse suitable for the above-mentioned aluminum-based sludge may not be efficiently performed. It is preferably 1.2 to 3 times. What exceeds 3 times cannot be industrially made in practice.

In the present invention, the chemical conversion treatment liquid transferred from the chemical conversion treatment tank is a step (2) for collecting sludge.
Attached to. The step (2) for recovering the sludge is not particularly limited, and for example, a conventionally known method can be used, and examples thereof include filtration, centrifugation, drying by heating, and the like. Is preferred. The filtration is usually performed by sending the entire amount of the chemical conversion treatment liquid transferred from the chemical conversion treatment tank to a filtration device, and the sludge containing the aluminum-based sludge in the chemical conversion treatment liquid at a higher concentration than before treatment is Collected on the filtration membrane. The filtrate obtained by the above-mentioned filtration contains almost no sludge, and depending on the filtering conditions, visible sludge can be completely eliminated. The filtrate after the filtration can be returned to the chemical conversion treatment tank and reused as a chemical conversion treatment liquid.

As the above-mentioned filtration, a cloth type filter or the like which is usually used can be used from the viewpoints of high recovery rate and easy maintenance, and the diameter is 1 to 50.
Those having innumerable pores having a size of μm or less are preferable. 50 μm
If it exceeds, sludge may pass through the filtrate and come out. It is preferably 3 to 10 μm. The filtration area is preferably 1 to 50 m ² . If it is less than 1 m ² , the liquid passing speed may be slow, which may be industrially disadvantageous. If it exceeds 50 m ² , it is not economical, and maintenance is required when clogging occurs, which is efficient. Not always.

The filtration may be carried out, for example, by sending the solution to a filtration device at a pressure of 0.8 to 3 kgf and filtering the entire amount of the chemical conversion treatment solution. The pressure is preferably 1 kgf.
By using the filtration device, sludge is continuously collected, and almost the entire amount of the chemical conversion treatment liquid is obtained as a filtrate,
It can be reused as a chemical conversion treatment liquid.

If the above filtration is continued for a certain period of time, for example, 4 hours or more, the filtration membrane may be clogged and the sludge recovery rate may increase, but the amount of filtrate may decrease. In this case, the amount of filtrate can be recovered by performing back washing. The method of backwashing is not particularly limited, but depending on the filtering device used, for example, air can be used. The backwash water thus recovered may be recovered and, if necessary, subjected to concentration and evaporation treatment steps and the like, and then reused together with the sludge containing the aluminum-based sludge obtained as described above. Further, when the clogging is not eliminated by air, dilute nitric acid can be further used.
From the viewpoint of efficient filtration, it is preferable that the above-mentioned filtration be provided with a plurality of filters and switched during backwashing. In the case of the filtration, when the chemical conversion treatment liquid is continuously treated, it is preferable to periodically perform the backwash.

The filtration is performed with a diameter of 7 to 15 cm and a length of 80.
It is preferable to use a filter capable of using about 10 to 30 tubular filters of 120 m to collect sludge on the outside of the filter and performing back washing with pressurized air from the inside of the filter. As such a filter, for example, a commercially available product can be used, and for example, a UF type filter series manufactured by Sankyo Giken Co., Ltd. is preferably used.

The recovered sludge recovered by the above-mentioned filtration depends on the metal composition of the object to be subjected to the phosphate chemical conversion treatment and the conditions of each of the above-mentioned steps. It is preferable to contain 15% or more of aluminum-based sludge. If it is less than 15%, the content rate of the above-mentioned aluminum-based sludge in the obtained sludge may be too low, and it may be difficult to be suitably used for a recycling method suitable for the above-mentioned aluminum-based sludge. It is preferably at least 20%.

In the present invention, the phosphate chemical conversion treatment liquid is transferred from the lower part of the chemical conversion treatment tank to the recovery tank, separately from the step (1) of transferring at the above (1/2) H position. It is preferable to be attached to (3). By performing the transfer step (3) from the lower part of the chemical conversion treatment tank to the recovery tank, the iron-based sludge having a high concentration in the lower part of the chemical conversion treatment tank can be selectively removed, and the phosphate chemical conversion treatment can be performed. The pot life of the liquid can be extended.

The lower part of the chemical conversion treatment tank means (1/2) when the minimum value (mm) of the liquid level of the chemical conversion treatment tank is H.
The position is not particularly limited as long as it is less than H, but it is preferably a position apart from the transfer position in the step (1) in terms of selectively increasing the concentration of sludge.
It is more preferably at a position of (1/3) H or less, and further preferably at the bottom of the chemical conversion treatment tank.

The recovery tank is not particularly limited and, for example, one normally used in wastewater treatment for solid-liquid separation or the like can be used. For example, a tank having a volume of 1/10 to 1/2 of that of the chemical conversion treatment tank can be used, and a settling tank that is usually used for line maintenance may be used. Specifically, when the chemical conversion treatment tank is about 100 tons, it is 1 to ³⁰ m ³ , and the height is 0.8 to 1.
An 8 m tank can be used. The recovery tank preferably has a hopper in order to promote settling of sludge, particularly iron-based sludge having a relatively high specific gravity. The hopper is not particularly limited, and includes, for example, the recovery tank 1
1 to 5 pieces are listed per piece, and a plurality of pieces are preferable from the viewpoint of increasing the sedimentation amount of iron-based sludge.

The volume of the recovery tank is 1/1 of that of the chemical conversion treatment tank.
The amount of 0 to ½ makes it possible to continuously pass through the phosphate chemical conversion treatment liquid for treatment, and it is generally necessary to use a batch method which requires much labor. Since it can be eliminated, it is preferable from the viewpoint of labor saving of the process, industrial application, and the like.

The flow rate of transfer to the recovery tank depends on the volume and shape of the recovery tank, but in general, the volume of the chemical conversion treatment liquid in the chemical conversion treatment tank is about 0.8 to 2% per minute. It is preferable to transfer the processing liquid. If it is less than 0.8%, a large amount of sludge is accumulated in the chemical conversion treatment tank, and the life of the phosphate chemical conversion treatment liquid is shortened. If it exceeds 2%, sedimentation of sludge, especially iron-based sludge becomes insufficient, or the volume of the recovery tank must be increased, which is not efficient.
Preferably, it is 0.9 to 1.7% / min based on the volume of the chemical conversion treatment liquid in the chemical conversion treatment tank.

The residence time of the phosphate chemical conversion treatment liquid in the recovery tank depends on the transfer flow rate to the recovery tank, the volume of the recovery tank, etc., but is preferably 6 to 16 minutes.
If it is less than 6 minutes, sedimentation of sludge, particularly iron-based sludge will be insufficient, and if it exceeds 16 minutes, it will take too much time to achieve efficient sludge removal. It is preferably 8 to 14 minutes.

After the transfer step (3) to the recovery tank, the entire amount can be transferred from the recovery tank, returned to the chemical conversion treatment tank, and reused as a chemical conversion treatment liquid. The transfer flow rate from the recovery tank can be determined in consideration of the transfer flow rate to the recovery tank, the evaporation amount from the recovery tank, the sludge transfer amount from the bottom of the recovery tank, etc. It is preferably adjusted so as to be substantially constant.

Since iron-based sludge is likely to precipitate at a lower content in the lower part of the recovery tank, it can be recovered from the bottom of the recovery tank and used for a suitable recycling method. The method of collecting from the bottom is not particularly limited, for example,
Examples include a method of extracting by a conventionally known method. The iron-based sludge is not particularly limited as a suitable recycling method, and for example, it can be recycled as a raw material for producing a phosphate pigment.

The sludge may be washed with tap water or pure water, dried, calcined, etc. before being used for reuse or in the process of reuse, if necessary. The method of drying is not particularly limited, and examples thereof include commonly used methods, but drying by a cylindrical dryer is preferable, and a conductive heating type cylindrical dryer in which at least one disk-shaped hollow rotary blade is installed. Is more preferable.

In the treatment by the recovery tank and the treatment by filtration, the phosphate conversion treatment liquid is continuously supplied to the recovery tank and the filtering device by making both the above-mentioned treatments in the recovery tank and the filtration continuous. It is preferable in that the sludge can be recovered and the filtrate can be reused continuously by passing the solution through the column, and there is no need to use a labor-intensive batch system.

In the sludge concentration method, the chemical conversion treatment tank (A) containing the phosphate chemical conversion treatment liquid and the chemical conversion treatment tank (A) are used.
When the minimum value (mm) of the liquid level of H is (1 /
2) It can be carried out by a sludge concentrating device characterized by including a transfer unit (B) installed at a position of H or higher and a sludge recovery device (C) connected to the transfer unit (B). . Such a sludge concentrating device is also one aspect of the present invention.

The transfer unit (B) is composed of a liquid feed pipe for transferring the phosphate chemical conversion treatment liquid from the chemical conversion treatment tank (A) to the sludge recovery device (C). The transfer unit (B) has a minimum liquid level height (m) of the chemical conversion treatment tank (A).
When m) is H, it is installed at a position of (1/2) H or more. The transfer unit (B) may be one in which an automatic valve and a pump interlocking with the liquid surface of the chemical conversion treatment tank (A) are installed as a means for adjusting the transfer flow rate.

The transfer unit (B) is further connected to the sludge recovery device (C). The sludge recovery device (C) is not particularly limited, but as described above, a filtration device is preferable, and a cloth filter is more preferable. The sludge recovery device (C) is preferably further connected by a pipe for returning the filtrate to the chemical conversion treatment tank.

It is preferable that the chemical conversion treatment tank (A) includes a unit (D) for transferring the phosphate chemical conversion treatment liquid to the recovery tank. The unit (D) for transferring to the recovery tank comprises a liquid feed pipe for transferring the phosphate chemical conversion treatment liquid from the chemical conversion treatment tank (A) to the recovery tank.

In the sludge concentrating method of the present invention, as described above, the concentration gradient is generated in the chemical conversion treatment tank, and among these, the content rate of the aluminum-based sludge having a relatively smaller specific gravity than the iron-based sludge is contained. By collecting the high upper layer portion, the content rate of the aluminum-based sludge with respect to the entire sludge can be increased.

The sludge of the present invention thus obtained, which has a higher content of the aluminum-based sludge, is
For example, it can be recovered by a method such as filtration, and can be efficiently provided for reuse suitable for the above aluminum-based sludge such as flux formation. The iron-based sludge is contained in the sludge extracted from the bottom of the recovery tank at a high content rate, and is efficiently used for a suitable recycling method such as phosphate pigmentation.

The sludge concentrating apparatus of the present invention is suitable for the above sludge concentrating method and makes it possible to easily selectively increase the concentration of the aluminum sludge. Therefore, the sludge concentrating method of the present invention, the concentrated sludge obtained by the above method, and the sludge concentrating apparatus are suitably used for phosphate sludge treatment of an object to be coated containing aluminum, iron and / or an alloy thereof, and particularly for automobiles. It can be suitably used in the pretreatment process for electrodeposition coating of the car body or parts.

[0046]

EXAMPLES The present invention will be described in more detail with reference to the following examples.
As will be apparent, the present invention is not limited to these examples.
is not.Example 1 (Pretreatment for painting) Commercially available cold-rolled steel plate automobile parts
Degreaser (Surf Cleaner EC92, Nippon Paint Co., Ltd.
Manufactured), and the processing area for each time unit is 400 m² /Time
As a result, after soaking at 40 ° C for 120 seconds, 20 seconds
2 times spray treatment, wash with water, then surface conditioning
2 using an agent (Surf Fine 7, manufactured by Nippon Paint Co., Ltd.)
After immersion treatment at 0 to 30 ° C for 30 seconds, a chemical conversion treatment solution (support
-Fudine SD6350, manufactured by Nippon Paint Co., Ltd.) at 35 ° C
Was soaked for 120 seconds and subjected to phosphate chemical conversion treatment.

(Sludge concentration treatment) The chemical conversion treatment liquid after the treatment is contained in the chemical conversion treatment tank 1 in an amount of 100 tons as shown in FIG. From the transfer liquid-feeding pipe installed in No. 1 to the filtration device 2 (UF-75 type UF type filter, manufactured by Sankyo Giken Co., Ltd.) at a flow rate of 1000 L / min, the pressure was 1 kgf to perform filtration. The chemical conversion treatment liquid flowing through the liquid supply pipe had iron-based sludge of 150 ppm and aluminum-based sludge of 40 ppm. The filtrate is
The sludge concentration was 0 ppm and the sludge was returned to the chemical conversion treatment tank 1. The filtration device 2 has a mesh size of 5 μm and a diameter of 10 c.
Approximately 20 cloth type tubular filters with a length of 1 m and a length of 1 m are used, and the filtration area is 7.2 m ^2.
A backwash was used every hour. On the other hand, from the bottom of the chemical conversion treatment tank 1 through the liquid feed pipe at a flow rate of 1000 L / min, the set ring tank 3 (Tada set ring tank, width 7 m
The solution was delivered to a position of a delivery pipe for transfer at a position of 3 m in length x 1.2 m in height and 0.2 m from the top).
In this case, the chemical conversion treatment liquid flowing through the liquid supply pipe contains 200 ppm of iron-based sludge and 40 pp of aluminum-based sludge.
It was m. Set the residence time in the settling tank 3 to 12
Minutes. The sludge settled in the settling tank 3 was 120 ppm of iron-based sludge and 12 ppm of aluminum-based sludge. Next, the chemical conversion treatment liquid containing 80 ppm of iron-based sludge and 28 ppm of aluminum-based sludge was returned to the chemical conversion treatment tank 1 from the settling tank 3.

(Evaluation) The aluminum-based sludge was 21.1% based on the mass with respect to the entire sludge collected by the filtration device 2. The aluminum-based sludge with respect to the entire sludge in the chemical conversion treatment liquid transferred from the lower part of the chemical conversion treatment tank 1 to the set rig tank is 1 by mass.
Since it was 6.7%, it increased to 1.26 times.

[0049]Example 2 Three hoppers 4 are attached to the bottom of the chemical conversion treatment tank 1.
The same process as in Example 1 was carried out except that and. To the filtration device 2
As for the chemical conversion treatment liquid flowing through the liquid transfer pipe, iron-based sludge is 130 p
pm and aluminum sludge is 40ppm
It was The sludge concentration of the filtrate is 0 ppm, and the chemical conversion treatment
It returned to the tank 1. Flow through the liquid transfer pipe to the settling tank 3
The chemical conversion treatment liquid contains 220 ppm iron-based sludge and
Minium sludge was 40 ppm. Setlin
The sludge that settled in the gut tank 3 is 1 iron-based sludge.
49ppm and 12ppm aluminum sludge
there were. Next, from the settling tank 3, iron-based
80 ppm of sludge and 28 of aluminum sludge
The chemical conversion treatment solution of ppm was returned to the chemical conversion treatment tank 1.

(Evaluation) The aluminum-based sludge was 23.5% based on the mass with respect to the entire sludge collected by the filtration device 2. The aluminum-based sludge with respect to the entire sludge in the chemical conversion treatment liquid transferred from the lower part of the chemical conversion treatment tank 1 to the set rig tank is 1 by mass.
Since it was 5.4%, it increased to 1.53 times.

[0051]Comparative Example 1 From the bottom of the chemical conversion treatment tank 1 to the filtration device 2 through the liquid delivery pipe.
The same process as in Example 1 was carried out except that the solution was added. Filtration equipment
Iron-based sludge is the chemical conversion treatment liquid flowing through the liquid feed pipe to the storage unit 2.
200ppm and 40ppm of aluminum sludge
Met. The filtrate has a sludge concentration of 0 ppm,
It was returned to the growth treatment tank 1. Liquid transfer pipe to settling tank 3
The chemical conversion treatment liquid flowing through the steel contains 200 ppm of iron-based sludge.
And aluminum-based sludge was 40 ppm. Set
Sludge that settled in the tring tank 3 is iron-based sludge.
120ppm for aluminum and 12p for aluminum sludge
It was pm. Then, from the settling tank 3,
80 ppm iron-based sludge and aluminum-based sludge
The chemical conversion treatment liquid of 28 ppm was returned to the chemical conversion treatment tank 1.

(Evaluation) The aluminum-based sludge was 16.7% on a mass basis with respect to the entire sludge recovered by the filtration device 2. The aluminum-based sludge with respect to the entire sludge in the chemical conversion treatment liquid transferred from the lower part of the chemical conversion treatment tank 1 to the set rig tank is 1 by mass.
Since it was 6.7%, it did not rise at the same level.

[0053]

Since the sludge concentration method of the present invention has the above-mentioned constitution, the sludge mixture containing the iron-based sludge and the aluminum-based sludge in the phosphate chemical conversion treatment liquid is treated in the chemical conversion treatment tank by the specific gravity of the metal. By utilizing the fact that the concentration gradient is generated in the above, it is possible to selectively increase the concentration, so that it can be efficiently used for reuse suitable for aluminum-based sludge.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a sludge concentration step in Example 1.

FIG. 2 is a schematic diagram of a sludge concentration step in Example 2.

FIG. 3 is a schematic diagram of a sludge concentration step in Comparative Example 1.

[Explanation of symbols]

1 Chemical conversion treatment tank 2 set ring tank 3 Filtration device 4 hopper

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B03B 5/28 C23C 22/86 C02F 11/00 ZAB B01D 29/04 510E C23C 22/86 29/38 510A 520A (72) Inventor Shoji Shiraishi 4-1-1-15 Minami-Shinagawa, Shinagawa-ku, Tokyo Japan Paint Co., Ltd. (72) Inventor Satoshi Miyamoto 4-1-1-15 Minami-Shinagawa, Shinagawa-ku, Tokyo Japan Paint Co., Ltd. (72 ) Inventor Yoshio Usagi 1 Toyota Town, Toyota City, Aichi Prefecture F-term inside Toyota Automobile Co., Ltd. (reference) 4D059 AA11 AA30 BE02 BE31 BE51 CC07 EB02 EB20 4D071 AA62 AB02 AB25 DA20 4K026 AA02 AA09 CA23 DA20

Claims (9)

[Claims] 1. A phosphate chemical conversion treatment liquid containing iron-based sludge and aluminum-based sludge, wherein H is the minimum liquid level height (mm) of the chemical conversion treatment tank of the phosphate chemical conversion treatment liquid. (1/2) A method of concentrating sludge, comprising a step (1) of transferring at a position of H or higher and a step (2) of recovering sludge from the transferred phosphate chemical conversion treatment solution. 2. The phosphate chemical conversion treatment liquid is subjected to a transfer step (3) from the lower part of the chemical conversion treatment tank to the recovery tank, separately from the step (1) of transferring at a position of (1/2) H or more. The method for concentrating aluminum-based sludge according to claim 1, wherein the sludge is concentrated. 3. The method for concentrating aluminum sludge according to claim 1, wherein in the step (2) of recovering sludge, the phosphate chemical conversion treatment liquid is filtered and the filtrate is returned to the chemical conversion treatment tank. . 4. The method for concentrating aluminum sludge according to claim 3, wherein the sludge is recovered by filtration. 5. The method for concentrating aluminum-based sludge according to claim 3, wherein the filtration is performed with a cloth filter. 6. The method for concentrating aluminum sludge according to claim 1, wherein the chemical conversion treatment tank is provided with a hopper at the bottom. 7. A concentrated sludge obtained by the method for concentrating aluminum-based sludge according to claim 1, 2, 3, 4, 5 or 6. 8. A chemical conversion treatment tank (A) containing a phosphate chemical conversion treatment liquid containing iron-based sludge and aluminum-based sludge, and a minimum liquid level height (m) of the chemical conversion treatment tank (A).
When m) is H, it includes a transfer unit (B) installed at a position of (1/2) H or more, and a sludge recovery device (C) connected to the transfer unit (B). A characteristic sludge concentrator. 9. The sludge concentrating device according to claim 8, further comprising a unit (D) for transferring the phosphate chemical conversion treatment liquid from the chemical conversion treatment tank (A) to the recovery tank.