JP3093912B2 - Processing method and equipment for pickling liquid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acid capable of preventing sludge from accumulating in ancillary facilities such as a pickling tank and a circulating tank for a metal material and efficiently discharging the sludge to the outside of the pickling treatment system. about the how to process of washing liquid.

[0002]

2. Description of the Related Art In general, when a metal material is pickled, a compound consisting of a surface scale and a metal and an acid solution may form sludge and deposit in a pickling tank and a circulating tank installed as necessary. is there. In particular, when a steel material such as stainless steel is treated with a pickling solution containing hydrofluoric acid, sludge solidifies in the tank, and this cleaning requires a great deal of labor and time (see Japanese Patent Publication No. 55-2476). These cleaning operations are only possible during shutdowns and must be performed using human naval tactics. Also, this operation is dangerous.

As a method for removing sludge during operation, a method using a screw conveyor (Japanese Patent Laid-Open No. 58-55)
No. 012), a method in which a feed member attached to two endless chains scrapes a pit groove provided at one end in the tank (see Japanese Utility Model Laid-Open No. 55-53508), and a scraper is attached to the pickling tank. A method using a settling tank (see Japanese Patent Publication No. 2-10874) is known. However, these methods do not disclose or suggest the method of the present invention described below.

[0004]

[0008] The present invention is to provide a process how that can be in operation to remove the sludge out of the pickling system. Another object of the invention is to provide
Together prevent the sludge is deposited in the circulation tank as a pickling tank or ancillary equipment, efficiently is to provide a process how that can remove the sludge. A further object is how to process that can be removed by converting the sludge into those easy handling to pickling systems outside the present invention
It is to provide.

[0005]

According to the present invention , (A)
Ejecting said pickling solution from a nozzle installed in the bottom of the circulation tank in the case and the circulation vessel from nozzles placed at the bottom of pickling tank for pickling a metal material with an acid containing hydrofluoric acid is present allowed the sludge in the pickling solution brought suspended without sedimentation in the tank, the substantially free of sludge in the solid-liquid separator part of the pickling solution containing the sludge suspended (B) no solid-liquid separation in a liquid and sludge, (C) the separated liquid circulates as the pickling solution, lime (D) separated sludge,
1 selected from slaked lime, quicklime or calcium carbonate
A method for treating a pickling liquid, comprising contacting with a seed or two or more kinds of neutralizing agents to neutralize and solidify, and (E) taking out the produced solid out of a pickling treatment system. Is done.

[0006]

The above objects of the present invention are achieved by these inventions. That is, according to these inventions, the sludge is soared by the jet flow spouted from the nozzle installed at the bottom of the pickling tank and the circulation tank, and the sludge is prevented from being deposited in the tank. Then, the pickling liquid containing sludge is sent to a solid-liquid separator such as a settling tank to perform solid-liquid separation, and the separated sludge is brought into contact with a neutralizing agent to be neutralized and solidified. The solid consisting of the sludge and the neutralized product of the acid and the neutralizing agent in the pickling solution is easy to handle and can be easily sent out of the pickling system. By setting the amount of sludge taken out of the system to be equal to or larger than the amount of generated sludge, the sludge in the pickling treatment system is not accumulated, and is maintained at a predetermined amount or less. Further, the acid in the pickling solution taken out as a neutralized substance out of the system can have the amount equal to or part of the amount of waste acid in the pickling tank. Absent.

Hereinafter, the present invention will be described in detail, by which other objects, configurations and advantages based thereon will become apparent.

FIG. 1 is a diagram showing a flow according to one embodiment of the present invention. In the pickling tank 1, for example, a stainless steel plate (not shown) is pickled. The pickling liquid overflowing from the pickling tank 1 is supplied to the circulation tank 2 via the flow path 8. The pickling liquid in the circulation tank 2 is returned to the pickling tank 1 via the flow path 9 by the pump 6. The circulation tank 2 is for replenishing a new liquid with a device (not shown) to adjust the concentration and the amount, or for storing the pickling liquid when draining the liquid in the pickling tank.

On the other hand, the pickling liquid in the pickling tank 1 having a relatively small amount of sludge is supplied to the nozzle of the pickling tank 1 or the circulating tank 2 by the pump 5 via the flow path 12 and the flow path 13, for example, an ejector 18. Be guided. Further, the pickling liquid in the circulation tank 2 is sent to the sedimentation tank 3 via the flow path 10 branched from the flow path 9 or sent directly from the circulation tank to the sedimentation tank 3 using a pump to be separated into solid and liquid. You. The clean pickling liquid substantially free of sludge separated in the settling tank 3 is returned to the circulation tank 2 via the flow path 11 and reused. Of course, circulation tank 2
When is not used, this clean pickling liquid is returned directly to the pickling tank 1. Further, the pickling liquid in the pickling tank 1 may be sent to the settling tank 3 for solid-liquid separation.

The sludge separated and settled in the settling tank 3 is introduced into the neutralization / solidification step 4 by opening the valve 7 at an appropriate time according to the settling amount. Of course, the process may be continuously introduced without installing a valve.

FIG. 2 is a diagram schematically showing a line extending from the pickling tank 1, the nozzle 18 provided at the bottom of the pickling tank 1, and the flow path 12 to the nozzle 18. Several nozzles are distribution pipes 17
And a plurality of distribution pipes 17 are provided at the bottom of the pickling tank 1. The nozzles are preferably installed on both sides of the pickling tank in order to avoid contact with the steel strip. The number of nozzles, the number of distribution pipes, the arrangement of distribution pipes, and the like can be appropriately designed according to the size and shape of the pickling tank 1. The jet direction of the jet from the nozzle is usually diagonally upward,
It can be changed appropriately for the purpose of preventing sludge accumulation.

The pickling liquid that has passed through the flow paths 12 and 13 by the pump 5 is led to the distribution pipe 17 through the flow path 14, the valve 15, and the flow path 16, and then is pickled from the nozzle 18 into the pickling tank 1. Squirted into the washing liquid. The spouting of the pickling liquid causes the sludge to rise and suspend in the liquid, thereby preventing the sludge from settling.

In the circulating tank 2, similarly to the pickling tank 1, a distribution pipe and a nozzle are provided, and the pickling liquid is spouted from the flow path 13 to prevent sludge accumulation. Further, a nozzle may be provided in a flow path connecting the pickling tank 1 and the sedimentation tank 3 and between the pickling tank 1 and the circulation tank 2 to eject the pickling liquid to prevent sludge accumulation.

FIG. 3 is a diagram schematically showing one embodiment of a processing step for neutralizing and solidifying sludge separated by solid-liquid separation. Sludge settled and separated in the settling tank 3 is quantitatively cut out by opening and closing the valve 7 and introduced into the kneader 19. This sludge is mixed with a small amount of pickling liquid, and the mixture contains 60 to 70% by weight as a metal compound, and the mixture is acidic. A neutralizer is supplied to the kneader 19 by a neutralizer line 20. In the kneader 19,
Neutralization and solidification are performed by kneading by means such as a twin screw conveyor. The solid formed consists of sludge and neutralized acid and neutralizer. This solid is sent to the lager bag 21.

Lime, slaked lime, quicklime, calcium carbonate and the like can be used as the neutralizing agent used in the above neutralization / solidification treatment. The amount of the neutralizing agent used can be appropriately determined in consideration of the amount of the pickling solution and the concentration of the acid contained in the separated sludge, and the transportability of the solid matter after the neutralization. Typically, the pH of the solid is 10
It is preferable to use a neutralizing agent so as to be ~ 11.

[0017]

EXAMPLE A pickling tank 1 having a length of 20 m, a width of 2.45 m and a height of 1.2 m is provided with 20 nozzles arranged at intervals of 1 m on both sides of the pickling tank 1. The pickling liquid was sprayed at a flow rate of 2 m ³ / H per nozzle at an angle of about 30 °. At this time, the pickling liquid was sprayed intermittently in order with three nozzles as one unit. The injection time was about 15 seconds. On the other hand, the pickling liquid (20 m ³ / H) in the circulation tank 2 was introduced into the settling tank 3 through the channel 10. The circulation amount of the pickling liquid between the pickling tank and the circulation tank was set to 60 m ³ / H.

Using 43 g of lime per 100 g of sludge separated in the settling tank 3, the mixture was kneaded in a kneader 19 to neutralize and solidify. Due to the heat of reaction, the temperature inside the kneader 19 reached 107 ° C. at the highest temperature. The obtained solid material had no adhesion and was excellent in transportability.

[0019]

According to the present invention, sludge can be efficiently removed from the system even during operation, and sludge is prevented from being deposited in the pickling tank and the circulation tank. it can. Further, there are the following advantages. (1) When the method of the present invention is applied to existing equipment, there is little modification of the pickling tank, so that the downtime of operation is short and the equipment cost is low. (2) The risk of contact between the nozzle and the steel strip in the pickling tank is small. (3) The sludge extracted from the sedimentation tank is neutralized and solidified, and the generated solid can be easily handled. (4) The acid solution that disappears in the neutralization treatment is equal to or part of the acid solution to be subjected to the waste acid treatment, and thus is not lost.

[Brief description of the drawings]

FIG. 1 is a flowchart showing one embodiment of a processing method and processing equipment of the present invention.

FIG. 2 is a view schematically showing an pickling tank and a nozzle installed at the bottom thereof.

FIG. 3 is a view showing one embodiment of a processing step for neutralizing and solidifying separated sludge.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pickling tank 2 Circulation tank 3 Sedimentation tank 4 Neutralization / solidification process 5 Pump 6 Pump 7 Valve 8 Flow path 9 Flow path 10 Flow path 11 Flow path 12 Flow path 13 Flow path 14 Flow path 15 Valve 16 Flow path 17 Distributing pipe 18 Nozzle 19 Kneader 20 Neutralizer line 21 Lager bag

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Junichi Yamamoto 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Works Co., Ltd. Chiba Works (72) Inventor Takeshi Sugimoto 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki (56) References JP-A-63-291608 (JP, A) JP-A-2-14964 (JP, U) JP-A-62-39808 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23G 1/36 C23G 3/00

Claims (1)

(57) [Claims] 1. A nozzle provided at the bottom of a pickling tank for pickling a metal material with an acid containing hydrofluoric acid, and a nozzle provided at the bottom of the circulating tank when a circulating tank is provided. and allowed ejecting the pickling solution from the nozzle allowed suspended sludge in the pickling solution without precipitation in the tank, (B) partially solid-liquid separation of the pickling solution containing the suspended sludge Solid-liquid separation into sludge-free liquid and sludge with the device,
(C) the separated liquid circulates as the pickling solution, (D) lime separated sludge, slaked lime, quick lime or carbonate
Contacting with one or more neutralizing agents selected from calcium to neutralize and solidify, and (E)
A method for treating a pickling liquid, wherein the produced solid is taken out of the pickling treatment system.