WO2019098590A1

WO2019098590A1 - Apparatus and method for purifying waste water from steel mills

Info

Publication number: WO2019098590A1
Application number: PCT/KR2018/013417
Authority: WO
Inventors: 홍완기; 유석진; 김경석
Original assignee: 주식회사 포스코
Priority date: 2017-11-14
Filing date: 2018-11-07
Publication date: 2019-05-23
Also published as: KR101958982B1

Abstract

Disclosed is an apparatus for purifying waste water from steel mills. The apparatus for purifying waste water according to an embodiment of the present invention comprises: a dirty tank which is charged with waste water containing sludge; a first particle refinement device which is supplied with the waste water from the dirty tank and pulverizes the sludge into fine particles; a first settling tank which is supplied with the sludge pulverized by the first particle refinement device and separates the same into fat, unseparated sludge, and iron particles by using differences in specific gravity; a Hoffmann filter which is supplied with the fat-containing water separated by the first settling tank and filters out the fat; and a first magnetic separator for removing iron particles from the water provided from the Hoffmann filter.

Description

Purification method of aqueous solution and purification of aqueous solution of steel mill

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for purifying an aqueous solution of a steelworks, and more particularly, to an apparatus for efficiently purifying foreign matters in an aqueous solution generated in a steelworks.

Generally, cooling water is used to remove impurities such as oil on the surface of a steel sheet during cooling or degreasing of the roll of the rolling mill during the rolling process, where impurities such as iron particles and oil are generated.

These impurities require a process of removing iron and sludge in order to reuse the aqueous solution. Unless the step of removing the impurities (iron powder + sludge) is carried out, in the case of rolling oil, the cooling nozzles are clogged by the impurities when the aqueous solution is reused and foreign substances remain on the surface of the steel sheet. When the rolling oil is left in this way, The surface of the steel sheet is discolored and colored, or surface defects such as roll marks due to other foreign substances are caused on the surface of the steel sheet.

Conventionally, as a method for removing iron powder and impurities in rolling oil and degreasing aqueous solution, there are a method of removing iron powder by using electromagnetic force, a method of removing iron by a precipitation separation method classified by particle size, and a flow path, And the like.

Patent Publication No. 2010-0011612 discloses a method for removing iron-containing impurities from pulverized rolling oil by adding a non-contact electromagnet to improve the performance of a cyclone filter using centrifugal force, and Patent Publication No. 2009-0067406 A method for differently operating a process for removing iron particles by particle size by a wet cyclone filter that separates iron particles by particle sizes in an electrolytic clean line is disclosed in Patent Publication No. 2016-0024678, To thereby remove impurities in the contaminated cleaning liquid when the impurities are congested.

However, the method of removing such impurities is difficult to ensure the removal performance by the electromagnetic force because the sludge is combined with the iron particles (fe particles) and the fat (fat), and the ability of the wet cyclone filter to remove iron particles by the fine particles is limited , The partitioning walls of the filtering section can not be removed except for the large size of the impurities, and thus the filtering performance is limited.

Embodiments of the present invention provide an apparatus capable of efficiently purifying foreign matter in an aqueous solution generated in a steelworks.

According to an aspect of the present invention, there is provided a dirty tank comprising: a dirty tank filled with an aqueous solution including a sludge; a first particle refinement device for supplying the aqueous solution from the dirty tank and pulverizing the sludge into fine particles; A first sedimentation tank which receives fine sludge from the first particle refinement apparatus and separates the sludge into fat, fine separation sludge (fe + fat fine particle) and iron (fe) by a specific gravity difference; There is provided an apparatus for purifying an aqueous solution of an iron mill including a Hoffman filter for supplying and filtering a separated aqueous solution of the oil and a first magnetic separator for removing iron from the aqueous solution provided in the Hoffman filter.

A second particle refining apparatus that receives the unseparated sludge from the first settling tank and crushes the unseparated sludge into fine particles, and a second settling tank that receives the finely divided aqueous solution from the second particle refining apparatus and separates the unfractionated sludge into oil and iron by a specific gravity difference, .

Also, the aqueous solution of the oil separated in the second settling tank may be provided as the Hoffmann filter.

In addition, the aqueous solution of iron separated in the first settling tank and the aqueous solution of iron separated in the second settling tank may be provided in the second magnetic separator.

And a backwash filter supplied with the aqueous solution from the first magnetic separator to provide a subsequent process.

In addition, the first particle refinement apparatus and the second particle refinement apparatus are characterized in that the sludge is refined by a shearing force acting on the gap between the rotor and the fixed stator, respectively, which are rotating.

And the gap of the second particle refinement apparatus is smaller than that of the first particle refinement apparatus.

The aqueous solution also includes a rolling oil or a degreasing solution.

According to another aspect of the present invention, there is provided a sludge treatment method comprising the steps of: receiving an aqueous solution used in a steel mill; finely sludge of an aqueous solution supplied using the first particle refining apparatus to separate the sludge into iron powder and oil powder; (Fe + fat fine particles) and Fe (Fe) by a specific gravity difference using a first settling tank, and the aqueous solution of the oil separated from the first settling tank was separated by a Hoffmann filter A method of purifying an aqueous solution of an iron mill to remove impurities using at least one of the magnetic separators may be provided.

Further, the unseparated sludge separated from the first settling tank is refined once again using a second particle refinement apparatus, and is then provided to a second settling tank. The untreated sludge is separated into oil and iron by a specific gravity difference, The impurities can be removed using at least one of a Hoffman filter and a magnetic separator.

In the embodiments of the present invention, the impurities of the aqueous solution are finely divided and separated, and then the iron powder and the oil are individually filtered to remove impurities from the aqueous solution. Therefore, It is possible to prevent the deterioration of the filtering process due to the clogging, the addition of the back washing process, the pressure and flow rate fluctuation of the cleaning solution supply line, and the influence of the electromagnetic force due to the iron and sludge combination.

1 schematically shows an apparatus for purifying an aqueous solution of a steel mill according to an embodiment of the present invention.

2 schematically shows a particle refinement apparatus according to an embodiment of the present invention.

3 is a cross-sectional view schematically showing a first settling tank according to an embodiment of the present invention.

4 is a plan view showing an air gap plate according to an embodiment of the present invention.

5 is a cross-sectional view schematically showing a second settling tank according to an embodiment of the present invention.

6 and 7 are flowcharts illustrating the process of removing oil contained in the sludge according to an embodiment of the present invention.

FIGS. 8 and 9 are flowcharts illustrating a process of removing iron contained in sludge according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below are provided by way of example so that those skilled in the art will be able to fully understand the spirit of the present invention. The present invention is not limited to the embodiments described below, but may be embodied in other forms. In order to clearly explain the present invention, parts not related to the description are omitted from the drawings, and the width, length, thickness, etc. of the components may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

FIG. 1 is a schematic view of an apparatus for purifying an aqueous solution of a steelworks according to an embodiment of the present invention. FIG. 2 is a schematic view of a particle refinement apparatus according to an embodiment of the present invention, FIG. 4 is a plan view showing an air gap plate according to an embodiment of the present invention, and FIG. 5 is a cross-sectional view schematically showing a second settling tank according to an embodiment of the present invention. to be.

The apparatus for purifying the aqueous solution 10 of the steelworks according to the present embodiment is an apparatus for removing impurities contained in an aqueous solution used for cooling the steel sheet and removing minute substances on the surface of the steel sheet during the rolling process and the degreasing process.

The aqueous solution of this embodiment includes rolling oil used in the rolling process or a degreasing solution used in the degreasing process, but the following description will be made by taking the case of being used in the rolling process as an example.

Referring to FIG. 1, the aqueous solution refining apparatus 10 of the present embodiment includes a dirty tank 20, a first particle refinement apparatus 30, a first settling tank 40, a Hoffman filter 50 A first magnetic separator 60, a second particle refinement device 70, a second settling tank 80, a second magnetic separator 90, and a backwash filter 100 do.

The dirty tank 20 stores the rolling oil that is discharged after being used in the rolling facility 15.

The rolling oil is discharged from an upper portion of a roll stand provided with a plurality of rolls. The discharged rolling oil is collected into a lower portion of a rolling housing containing a plurality of roll stands, and then supplied to the dirty tank 20.

The dirty tank 20 may be provided with a magnetic separator for removing iron powder from the stored rolling oil.

The first particle refinement apparatus 30 may be configured such that before the sludge as an impurity contained in the aqueous solution provided in the dirty tank 20 is supplied to the Hofmann filter 50 or the

magnetic separator

60 or 90, and separates and separates into fine particles (fe particles) and oil fractions (fat particles).

In the case of filtering sludge particles bound with iron and oil, it is difficult to ensure iron removal performance due to overflow due to clogging due to sludge in Hoffman filter 50, which is a subsequent process, It is difficult to remove the iron powder by the magnetic force by the sludge combined with the iron powder, and the back washing process due to the adhesion of the wall due to the viscosity of the sludge is additionally required. Such a backwash process is operated with the on / off function, which causes fluctuations in the pressure and flow rate of the line supplying the aqueous solution, thereby causing an adverse effect of lowering the supply performance of the rolling oil.

Accordingly, the first particle refinement apparatus 30 may be configured such that the sludge particles, to which iron particles and fat are combined, are pulverized and separated into fine particles in advance before they are supplied to a subsequent process, It is possible to improve the impurity removing performance of the Hofmann filter, the magnetic separator and the back washing filter by preventing the operational difficulties due to the differential pressure due to clogging and the deterioration of the attaching ability of the magnetic separator.

The first particle refinement apparatus 30 may be provided with a device for refining sludge by a shearing force acting on the gap g between the rotating rotor 31 and the fixed stator 33 as shown in FIG. have.

The sludge repeatedly receives shearing, compressing, and impacting at the gap portion between the rotor 31 and the stator 33 according to the magnitude of the clearance g between the rotor 31 and the stator 33 and the relative rotational speed, It is separated into iron (fe particle) and oil (fat).

The sludge pulverized into fine particles in the first particle refinement apparatus 30 is supplied to the first settling tank 40.

The first sedimentation tank 40 receives the finely pulverized sludge aqueous solution by the first particle refinement apparatus 30 and converts the aqueous solution supplied by the specific gravity difference into fat, unseparated sludge (fe + fat fine particles) which is divided into three layers divided into fe particles.

3 and 4, the first settling tank 40 may be formed of a cylindrical container 41 filled with an aqueous solution. Inside the container 41, a disc-shaped air gap A plate 42 is disposed.

The porous plate 42 is provided with an aqueous solution absorbing port 43 and an interlayer moving hole 44 formed so as to pass through the upper and lower portions of the porous plate 42. A moving pipe 45 communicating with the aqueous solution absorbing port 43 is formed at the center of the air electrode plate 42 Respectively.

The aqueous solution filled in the first settling tank 40 freely passes through the interlayer transfer hole 44 and passes through the oil layer, the unseparated sludge layer (fe + fat binder) and the iron powder layer (fe particle.

The aqueous fat solution present in the upper portion of the first settling tank 40 is pumped by the operation of the first oil supply pump 46 and is provided in a subsequent process, The sludge aqueous solution is pumped by the drive of the unseparated sludge supply pump 47 and is provided to a subsequent process. The aqueous solution of iron present in the lower part of the first settling tank 40 is pumped And is provided as a subsequent process.

The first oil feed pump 46 is operated to pump the aqueous solution of the oil above the first settling tank 40 until the water level sensor 49a located at the top senses the height of the aqueous solution and the unseparated sludge supply pump 47 Is operated to pump the unseparated sludge aqueous solution located in the middle of the first settling tank 40 until the level sensor 49b located below detects the height of the aqueous solution.

The oil aqueous solution pumped by the first oil feed pump 46 in the first settling tank 40 is supplied to the Hoffman filter 50.

The Hoffmann filter 50 comprises a medium 51 for filtering the aqueous solution of the oil supplied from the first settling tank 40 to remove impurities and a conveyor chain for conveying the medium 51.

The aqueous solution filtered through the Hoffman filter 50 is supplied to the first clean tank 61 and the remaining iron powder is removed by the first magnetic separator 60 installed in the first clean tank 61.

The aqueous solution from which the iron particles have been removed by the first magnetic separator 60 can be finally purified to the backwash filter 100 and then supplied to the rolling facility 15.

The unseparated sludge aqueous solution pumped by the unseparated sludge feed pump 47 in the first settling tank 40 is provided to the second particle refinement apparatus 70.

The second particle refinement apparatus 70 has the same structure as the first particle refinement apparatus 30 but comprises a rotor 31 and a stator 33 for crushing sludge not separated by the first particle refinement apparatus 30. [ Is set to be much denser than that of the first particle refinement apparatus (30).

The unseparated sludge pulverized into fine particles in the second particle refinement apparatus 70 is supplied to the second settling tank 80.

The second sedimentation tank 80 receives the finely divided aqueous sludge solution that has been finely ground by the second particle refinement apparatus 70 and is divided into fat and Fe particles by the difference in specific gravity Separate into two layers.

5, the second settling tank 80 may be formed of a cylindrical container 81 filled with an aqueous solution therein, and a disk-shaped void plate 42 is disposed below the inside of the container 81 do.

The aqueous solution filled in the second settling tank 80 is freely passed through the interlayer movement hole 44 and is separated into a fat layer and a Fe particle after a lapse of time.

The aqueous solution of the oil present in the upper portion of the second settling tank 80 is pumped by the operation of the second oil supply pump 82 to be supplied to the subsequent process and the aqueous solution of iron present in the lower portion of the second settling tank 80 is supplied to the second And is pumped by the driving of the iron feed pump 83 to be supplied to a subsequent process.

The second oil feed pump 82 is operated to pump the aqueous solution of the oil in the upper portion of the second settling tank 80 until the level sensor 84 disposed in the vicinity of the disc shaped air gap plate 42 senses the height of the aqueous solution .

The aqueous solution pumped by the second oil feed pump 82 in the second settling tank 80 is supplied to the Hoffman filter 50 and the aqueous solution filtered in the Hoffman filter 50 is supplied to the first clean tank 61 The iron powder is removed by the first magnetic separator 60 and can be supplied to the rolling mill 15 after being finally purified in the backwash filter 100.

The second clean tank 91 receives and stores the aqueous iron solution from the first settling tank 40 and the second settling tank 80 and the second magnetic separator 90 provided in the second clean tank 91 stores Remove iron powder.

Hereinafter, a process of purifying sludge by an aqueous solution refining apparatus of a steelworks according to an embodiment of the present invention will be described.

Referring to FIG. 6, an aqueous solution such as rolling oil, degreasing solution used in a rolling facility or a degreasing facility is supplied to and stored in a dirty tank 20.

The aqueous solution stored in the dirty tank 20 is supplied to the first particle refinement apparatus 30. [

The first particle refinement apparatus 30 finerizes and separates the sludge contained in the provided aqueous solution using a shearing force generated by the gap between the rotor 31 and the stator 33, and provides the sludge to the first settling tank 40.

The aqueous solution provided in the first settling tank 40 is stabilized after a predetermined time and is divided into three layers of fat, un-separated sludge (fe + fat fine particle) and iron particle (fe particle).

The aqueous solution of oil in the upper portion of the first settling tank 40 is pumped to the outside by operating the first oil supply pump 46. The first oil supply pump 46 is stopped when the height of the aqueous solution is detected by the water level sensor 49a.

The aqueous solution supplied by the first oil feed pump 46 is purified through a Hoffman filter 50, a first magnetic separator 60, a backwash filter 100, and then supplied to a rolling facility.

Referring to Fig. 7, the aqueous solution stored in the dirty tank 20 is provided to the first particle refinement apparatus 30. Fig.

The first particle refinement apparatus 30 finerizes and separates the provided sludge using a shearing force generated by a gap between the rotor 31 and the stator 33, and provides the separated sludge to the first settling tank 40.

The unseparated sludge (fe + fat fine particle) aqueous solution located in the middle region of the first settling tank 40 is pumped to the second particle refining apparatus 70 by operating the unseparated sludge supply pump 47.

The separated sludge supply pump 47 is stopped when the height of the aqueous solution is detected by the water level sensor 49b.

The second particle refinement apparatus 70 separates the residual sludge that has not been separated into more fine iron particles (fe particles) and fat (fat) since the gap between the rotor 31 and the stator 33 is reduced to increase the shear force And supplied to the second settling tank 80.

The aqueous solution provided in the second settling tank 80 is stabilized after a certain period of time and divided into two layers of oil and iron.

The aqueous solution of the oil in the upper part of the second settling tank 80 is pumped to the outside by operating the second oil supply pump 82. The second oil supply pump 82 is stopped when the height of the aqueous solution is detected by the water level sensor 84.

The aqueous solution supplied by the second oil feed pump 82 is purified through the Hoffman filter 50, the first magnetic separator 60 and the backwash filter 100 and then supplied to the rolling facility 15.

Referring to FIG. 8, an aqueous solution such as rolling oil, degreasing solution used in a rolling facility or a degreasing facility is supplied to and stored in a dirty tank 20.

The aqueous solution of iron powder located in the lower part of the first settling tank 40 is pumped to the outside by operating the first iron supply pump 48.

The aqueous solution supplied by the first iron supply pump 48 is supplied to the dirty tank 20 via the second magnetic separator 90. [

Referring to Fig. 9, the aqueous solution stored in the dirty tank 20 is provided to the first particle refinement apparatus 30. Fig.

The second particle refinement apparatus 70 reduces the gap between the rotor 31 and the stator 33 by giving a higher shear force to the first particle refinement apparatus 30 so that the residual sludge that has not been separated is separated into finer iron particles, And then supplied to the second settling tank 80. [0050]

The aqueous solution of iron located in the lower part of the second settling tank 80 is supplied to the dirty tank 20 through the second magnetic separator 90 by operating the second iron supply pump 83.

Through this method, the aqueous solution refining apparatus 10 of this embodiment separates the impurities of the aqueous solution in advance and separates the separated impurities, and separates the separated iron particles (fe particles) and oil (fat) The cleaned rolling oil and the degreasing solution can be supplied.

The foregoing has shown and described specific embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

A dirty tank filled with an aqueous solution including a sludge;

A first particle refinement device that receives the aqueous solution from the dirty tank and pulverizes the sludge into fine particles;

A first sedimentation tank which receives fine sludge from the first particle refinement apparatus and separates the sludge into fat, fine separation sludge (fe + fat fine particle) and iron (fe) by a specific gravity difference;

A Hoffman filter for receiving and filtering the aqueous solution separated in the first settling tank; And

And a first magnetic separator for removing iron particles from the aqueous solution provided in the Hoffman filter.
The method according to claim 1,

A second particle refinement apparatus that receives the unseparated sludge from the first settling tank and crushes the unseparated sludge into fine particles; And

And a second settling tank for receiving the micronized aqueous solution in the second particle refinement apparatus and separating the micronized aqueous solution into oil and iron by a specific gravity difference.
3. The method of claim 2,

Wherein the oil aqueous solution separated from the second settling tank is provided as the Hoffman filter.
3. The method of claim 2,

Wherein the aqueous solution of iron separated in the first settling tank and the solution of iron separated in the second settling tank are provided in a second magnetic separator.
The method according to claim 1,

Further comprising a backwash filter supplied with the aqueous solution from the first magnetic separator to provide a subsequent process.
3. The method of claim 2,

Wherein the first particle refinement apparatus and the second particle refinement apparatus refine the sludge by a shear force acting on a gap between a rotating rotor and a fixed stator, respectively.
The method according to claim 6,

Wherein the gap of the second particle refinement apparatus is smaller than that of the first particle refinement apparatus.
The method according to claim 1,

Wherein the aqueous solution comprises a rolling oil or a degreasing solution.
Receiving the aqueous solution used in steelworks,

The sludge of the aqueous solution supplied by using the first particle refinement device is finely divided into iron powder and oil powder,

The micronized sludge aqueous solution supplied from the first particle refinement apparatus is separated into fat, un-separated sludge (fe + fat fine particle) and iron (fe) by a specific gravity difference using a first settling tank,

A method for purifying an aqueous solution of a steel mill for removing impurities by using at least one of a Hoffmann filter and a magnetic separator, the oil aqueous solution separated from the first settling tank.
10. The method of claim 9,

The unseparated sludge separated in the first settling tank is further refined using a second particle refinement apparatus and then supplied to a second settling tank to separate into oil and iron by a specific gravity difference, A method for purifying an aqueous solution of a steel mill for removing impurities using at least one of a Hoffman filter and a magnetic separator.