KR20140055868A - Waste water treatment apparatus in die casting and method for the same - Google Patents

Abstract

The present invention relates to an apparatus and a method for treating die casting cleaning wastewater. The apparatus for treating die casting cleaning wastewater includes: a wastewater collection tank which collects wastewater generated after a die casting process; a chemical injection device which performs chemical treatment on the wastewater transported from the wastewater collection tank; a floating/separation device which supplies bubble water to the wastewater passing through the chemical injection device and floats and removes coagulated particles in the wastewater; and a membrane separation device which performs final treatment on the residual floating materials passed through the floating/separation device. According to the present invention, even the wastewater mixed with an emulsion type can be treated efficiently and water can be recycled, and thus operating costs can be minimized. In addition, stable wastewater treatment is possible.

Description

Technical Field [0001] The present invention relates to a method and apparatus for treating die-

More particularly, the present invention relates to an apparatus and method for treating wastewater from diecasting wastewater, and more particularly, to a wastewater treatment apparatus capable of efficiently treating wastewater containing pollutants such as mold release agents, oils and suspensions, minimizing operating costs, The present invention relates to an apparatus and a method for treating die-casting washing wastewater.

Die casting is a casting method in which molten metal is injected into a die under atmospheric pressure or higher, and is widely used in casting machine parts such as zinc, aluminum, copper, and magnesium alloys. Generally, it is used to manufacture thin parts of 1.5 ~ 5mm thickness. In the case of aluminum or copper alloy, it is possible to produce tens of thousands to hundreds of thousands of molds in one mold, and in the case of zinc, it can be produced almost indefinitely, so that it can be mass-produced in a short time. Recently, aluminum die-casts have been used up to cylinder blocks of small engines for passenger cars.

Therefore, it is used in various fields such as electric machinery and general machinery starting from automobile related parts. Specific examples include main cases and coverings such as transmission case, oil pump case, and rocker cover.

However, recent environmental degradation and depletion of fossil fuels have led to problems such as lighter weight and improved recyclability. As a result, there has been a growing demand for high-strength, high-toughness, high ductility, Diecasting of parts is also rapidly progressing.

In this die casting process, a large amount of water is used to clean the mold release agent sprayed on the mold so that the mold is cooled and the moldings are smoothly demoulded in the mold. In such a washing wastewater, a release agent, oil (hydraulic oil, hydraulic oil, etc.) Many contaminants are incorporated. In particular, the releasing agent is present in an emulsion state in which siloxane is the main component and dispersed in water using a surfactant, and thus it is difficult to remove the releasing agent from the washing wastewater. In spite of this, due to the advantages of the die casting process, the field application is expanding and the amount of washing wastewater generated is increased to 10% of the total wastewater generation amount in the factory.

At present, the washing wastewater is subjected to pretreatment using the oil water separator 30 to remove the oils in the wastewater, and the pretreated water is transferred to the wastewater treatment plant 80 and discharged after being appropriately treated. As the cost of water purchasing and wastewater treatment is expected to increase due to the recent rise in energy and drug costs, it is necessary to reduce water usage.

The oil recycling apparatus of the diecasting (Korean Patent Laid-Open Publication No. 2003-0084024) discloses a diecasting oil recycling method which comprises two stages of foreign matter removing screens and two stages of oil-water separating apparatuses , The oil mixed in the wastewater is recovered and recycled. This is advantageous in that the oil is recovered and recycled, but the separated water is transferred to the wastewater treatment plant and discharged after treatment, which is ineffective in terms of the amount of water purchased and the amount of wastewater generated. In addition, there is a disadvantage in that it is impossible to use the recovered oil as it is because the fine particles mixed in the wastewater can not be removed only by the screen operation, and the emulsion type in which the surfactant such as the release agent recently used is dispersed in water is very dispersed It is stable and can not be treated with simple oil water separator.

A method of recycling water after removing pollutants in wastewater (U.S. Patent Application Publication No. 2003-0070994) is a pretreatment method consisting of a water separation apparatus and a membrane separation apparatus, which can save money on chemicals and energy by selecting simple water separation , There is an advantage that the recycled water treated by applying the membrane separation device can be used immediately in the process. However, due to the fine particles not treated with oil separation, the fouling phenomenon frequently occurs during the membrane separation, resulting in a reduction in efficiency and an increase in operation cost due to frequent replacement due to membrane damage. In addition, the concentrated release agent wastewater is transferred to a wastewater treatment plant and treated, and there is a problem that the amount of chemicals used for coagulation may be increased due to dilution with other wastewater.

Therefore, it is necessary to develop technology that can recycle water while minimizing operating costs and reduce the environmental load that flows into the wastewater treatment plant.

It is an object of the present invention to solve the above-mentioned problems, and an object of the present invention is to provide a method and apparatus for efficiently treating wastewater mixed with an emulsion type and also capable of recycling water, minimizing operating costs, Apparatus, and method.

In order to accomplish the above object, the present invention provides a waste water collecting tank collecting wastewater generated after a die casting process in a preferred embodiment; A chemical injector for treating the wastewater transferred from the wastewater collecting tank; A floatation separation device for supplying bubble water to the wastewater that has passed through the medicine injection device to float and remove coagulated particles in the wastewater; And a membrane separation device for passing the residual suspended material through the floating separation device to final treatment.

At this time, the chemical injector may be installed in a pipe connecting the wastewater collecting tank and the floating separator, and includes a flocculant tank, a first ultrasonic device, and a first ultrasonic nozzle, Can be injected into the piping to be connected.

The coagulant may be any one selected from the group consisting of aluminum sulfate, sodium aluminate, aluminum polychloride, ammonium alum, potassium alum, ferrous sulfate, ferric sulfate and combinations thereof, % Liquid aluminum sulfate is injected into a pipe connecting the waste water collecting tank and the floating separator at a concentration of 1000 to 2500 ppm.

The chemical injector further includes a coagulation aid tank, a second ultrasonic device, and a second ultrasonic nozzle, and the coagulation aid may be further injected into the pipe connecting the flocculation tank and the floating separation device.

The coagulation assistant may be an organic polymer aggregate, specifically, a group consisting of starch, sodium alginate, glue, amine fulmarine, amine pyrrolidine, polyethyleneimine, polyacrylamide, sodium polyacrylate, and combinations thereof And can be any one selected.

The chemical injector injects the organic polymer flocculant into a pipe connecting the flocculant tank and the floatation separator at a concentration of 40 to 60 ppm.

The floating separation device includes a fine bubble generator; A mixing tank in which the micro-bubble supplied from the micro-bubble generator and the wastewater passing through the drug injection device are mixed; A float plate tilted to the upper side so that the coagulated particles agglomerated by the flocculating agent float by the minute bubbles; A skimmer for removing floated particles; A sludge storage tank for storing the removed condensed particles; A sludge discharge port through which sludge is discharged; And a treatment water tank in which the treated particles are moved; .

In this case, the micro-bubble generator is characterized in that micro-bubbles are generated by a pressurizing pump. The micro-bubbles supplied from the micro-bubble generator preferably have an average particle diameter of 10 to 80 μm, The time required for the minute bubbles supplied from the apparatus to stay in the mixing tank is 20 to 40 minutes.

According to another aspect of the present invention, there is provided a method for treating die-casting washing wastewater using the processing apparatus.

The present invention having the above-described structure can effectively treat diecasting washing wastewater, and can also stably treat wastewater mixed with an emulsion type.

In addition, the present invention can reduce the amount of water used and the amount of waste water discharged through cleaning and recycling the washing wastewater, thereby reducing the production cost.

In addition, the present invention minimizes the suspended solids flowing into the membrane of the membrane separator to reduce the backwash cycle, thereby improving the productivity of the recycled water and extending the service life of the membrane.

FIG. 1 is a view schematically showing an apparatus for treating die washing washing wastewater according to a preferred embodiment of the present invention, in comparison with a conventional treatment apparatus.
FIG. 2 is a diagram schematically showing a drug injection device according to a preferred embodiment of the present invention.
3 is a diagram schematically showing a floating separation apparatus according to a preferred embodiment of the present invention.
Fig. 4 is a view showing the principle of improving separation efficiency when using fine bubbles. Fig.
5 is a view showing the release agent agglomeration and floating principle mixed in wastewater.
6 is a diagram schematically showing a membrane separation apparatus according to a preferred embodiment of the present invention.
FIG. 7 is a graph showing the pollutant treatment efficiency in the case of wastewater treatment by an apparatus for treating diecasting washing wastewater according to a preferred embodiment of the present invention.

The present invention relates to a waste water collecting tank (20) for collecting wastewater generated after a die casting process (10); A chemical injector 40 for treating the wastewater transferred from the wastewater collecting tank 20; A float separation device (50) for supplying bubble water to the wastewater that has passed through the medicine injection device to float and remove coagulated particles in the wastewater; And a membrane separation device (70) for final treatment of the residual suspended material passing through the floating separation device (50).

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 is a view schematically showing an apparatus for treating die washing washing wastewater according to a preferred embodiment of the present invention, in comparison with a conventional treatment apparatus.

As shown in the drawing, conventionally, wastewater collected in a wastewater collecting tank 20 after a die casting process 10 is introduced into a water separator 30 for pre-treatment to remove oil flow, and the pre- (80), treated appropriately, and discharged as is. The above technique has the advantage of recovering oil and recycling the oil. However, there is no aspect in which the amount of water purchased and the amount of generated wastewater are reduced as the water separated and separated is discharged to the wastewater treatment plant and discharged.

Alternatively, the present invention may be modified such that the wastewater separating apparatus 30 is replaced with a flotation separating apparatus 50 to pre-treat wastewater collected in the wastewater collecting tank 20 after the die casting process 10, To treat the washing wastewater, thereby reducing the load on the water recycling and wastewater treatment plant.

Specifically, the apparatus for treating wastewater according to the present invention includes a wastewater collecting tank 20 for collecting wastewater generated after a die casting process 10; A chemical injector 40 for treating the wastewater transferred from the wastewater collecting tank 20; A float separation device (50) for supplying bubble water to the wastewater that has passed through the medicine injection device to float and remove coagulated particles in the wastewater; And a membrane separation device (70) for passing the residual suspended material through the floating separation device (50), and will be discussed in detail below.

1. A chemical injection device (40)

2 is a diagram schematically showing the drug injecting apparatus 40. The drug injecting apparatus 40 serves to destroy the release agent in an emulsion state in the wastewater and to inject the coagulant to flocculate the suspended particles The first ultrasonic device 42 and the first ultrasonic nozzle 43. The first ultrasonic device 42 and the first ultrasonic nozzle 43 are preferably provided with a waste water collecting tank 20 and a floating separation May be installed in a pipe connecting the device (50).

Specifically, when the washing wastewater containing a release agent, a suspended substance, and the like is moved from the wastewater collecting tank 20 to the floating separation device 50 in the die casting process 10, the first ultrasonic device 42 and the first ultrasonic wave The coagulant is injected into the pipe connecting the waste water collecting tank (20) and the floating separator (50) by the nozzle (43).

That is, the releasing agent and the like in the die casting washing wastewater are dispersed and stabilized in an emulsion state by a surfactant. In order to destroy the emulsion state, the pH or the temperature of the wastewater is generally changed or the opposite ion is added In the present invention, the coagulated particles are formed by adding a counterion by using a coagulant.

The coagulant is a drug that forms coagulated particles by neutralizing the surface charge of colloidal particles stabilized in water to cause instability or adsorption and crosslinking, and is a drug that easily hydrolyzes and provides a positive charge, such as aluminum salts and iron salts Specific examples thereof include aluminum sulfate, sodium aluminate, aluminum polychloride, ammonium alum, potassium alum, ferrous sulfate, ferric sulfate, or combinations thereof.

At this time, although the amount of the flocculant injected differs depending on the washing wastewater property, the coagulant consisting of 2 to 4% liquid sulfuric acid aluminum in a concentration of 1000 to 2500 ppm is added to the waste water collecting tank 20 And the flotation separating apparatus 50 are connected to each other.

Further, in order to improve the treatment efficiency of the floatation separating apparatus 50 in addition to the flocculating agent, an aggregating auxiliary agent may be further injected into the pipe connecting the flocculating agent tank 41 and the floatation separating apparatus 50. For this purpose, The injection device 40 may further include a flocculation aid tank 44 and may further include a second ultrasonic device 45 and a second ultrasonic nozzle 46 for injecting the flocculation aid.

In the present invention, an organic polymer flocculant is used. Examples of the flocculant include starch, sodium alginate, glutaraldehyde, amine fulmarine, , Polyethylenimine, polyacrylamide, sodium polyacrylate, or a combination thereof. The organic polymer flocculant may be added to the flocculant tank 41 and the float separator 41 at a concentration of 40 to 60 ppm in consideration of treatment efficiency and cost. It is preferable to inject it into a pipe connecting the pipe 50.

The present invention improves the dispersibility by the injection of the coagulant using the ultrasonic nozzle, so that the cost can be reduced by reducing the amount of the coagulant used by 30% compared with the general coagulation flocculation process (stirring using the impeller), thereby reducing the occurrence of sludge And can reduce costs. In addition, since the ultrasonic nozzles 43 and 46 can be used to coagulate the contaminants in the wastewater, it can be applied to a place having a narrow space. .

2. The floating separation device (50)

3 is a view schematically showing the floating separator 50. The microbubble generator 64 serves to float and separate the coagulated particles formed by the drug injector 40 into the micropores. A mixing tank 52 in which the micro-bubble supplied from the micro-bubble generator 64 and the wastewater passing through the chemical injector 40 are mixed; A float plate (53) tilted toward the top so that the coagulated particles agglomerated by the flocculant float by microbubbles; A skimmer 55 for removing floated condensed particles; A sludge storage tank 56 for storing the removed condensed particles; A sludge discharge port 57 through which sludge is discharged; And a treatment water tank 58 through which the treated water with the condensed particles is moved.

The coagulated particles formed through the chemical injector 40 are introduced together with the bubble water through the inlet 51 of the mixed liquid of the wastewater and the bubble water, and the fine bubbles are attached to the mixing vessel 52. The coagulated particles with fine bubbles float along the float plate 53, float in the floating tank 54, and are removed by the skimmer 55. FIG. 5 is a view showing the principle that the flocculant is added to the release agent mixed with the wastewater and the microbubbles are floated to the surface.

The removed coagulated particles are stored in the sludge storage tank 56 for a predetermined period of time and discharged through the sludge discharge port 57. The treated water is temporarily stored in the treated water tank 58 through the treated water outlet 59 and the treated water tank 60 via the treated water outlet 59. The temporarily stored process water is transferred to the membrane separation device 70 through the process water discharge pipe 61 and part of the process water is supplied to the microbubble generator 64 by the pressurizing pump 63 to generate microbubbles Lt; / RTI > In this process, air is introduced into the air inlet nozzle 62 and mixed with the water, minute bubbles are generated in the minute bubble generator 64 and are supplied to the floating separator 50 through the fine bubble supply pipe 65 .

At this time, it is preferable that the time for the microbubbles supplied from the microbubble generator to stay in the mixing tank is 20 to 40 minutes in consideration of the adhesion with the coagulated particles and the floating separation efficiency.

In addition, the microbubbles are more likely to adhere to the suspended particles than the conventional microbubbles (particle diameter of 100 to 1,000 占 퐉) to increase the floatability, thereby improving the treatment efficiency. If the average particle diameter of the microbubbles is less than 10 占 퐉, If the average particle size of the fine bubbles is less than 80 탆, the average particle diameter of the fine bubbles is preferably 10 to 80 탆,

Since the micro-bubble generator 64 of the present invention generates micro-bubbles by the pressurizing pump 63, there is an advantage that energy can be saved as compared with the micro-bubble generator using the compressor.

3. Membrane separator 70,

FIG. 6 is a view schematically showing a membrane separation device 70 according to a preferred embodiment of the present invention. The coagulated particles remaining in the treated water subjected to primary treatment by the floatation separation device 50, And the like are finally processed to produce recycled water.

The membrane used in the membrane separation apparatus 70 is a hollow fiber membrane (UF) commonly used in water purification and wastewater treatment, and is operated in an external pressure type while maintaining a pressure difference of about 1 bar. The basic principle is as shown in Fig. If the treatment efficiency of the floating separation device 50 is high, the floating substances (particles, oil, etc.) flowing into the separation membrane of the membrane separation device 70 can be minimized to reduce the fouling phenomenon, , Which leads to an increase in the production capacity of recycled water. Further, the lifetime of the separation membrane can be prolonged and economic efficiency can be secured

FIG. 7 is a graph showing the pollutant treatment efficiency in the case of wastewater treatment by an apparatus for treating diecasting washing wastewater according to a preferred embodiment of the present invention.

It can be confirmed that at least 90% of all contaminants (organic matters, suspended solids, oils, surfactants, etc.) have been removed when the apparatus and method for treating diecasting washing wastewater of the present invention are treated. Particularly, it was confirmed that 99% of the suspended substances can be removed.

In this way, the final treated water produced through this process is recycled to the process, and the concentrated waste liquid is transferred to the wastewater treatment plant and treated. When these technologies are applied to the field, the cost of purchasing water can be reduced by acquiring new water resources . In addition, by reducing the environmental burden on the wastewater treatment plant, it is possible to reduce waste water treatment costs and contribute to the stable wastewater treatment plant operation.

Although the present invention has been described in connection with the specific embodiments of the present invention, it is to be understood that the present invention is not limited thereto. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. Various modifications and variations are possible.

10: die casting process 20: waste water collecting tank
30: Oil water separator 40: Drug injector
41: coagulant tank 42: first ultrasonic device
43: first ultrasonic nozzle 44: coagulation aid tank
45: second ultrasonic device 46: second ultrasonic nozzle
50: floating separation device 51: inlet
52: mixing tank 53: floating plate
54: Floating column 55: Skimmer
56: sludge storage tank 57: sludge discharge port
58: treated water tank 59: treated water outlet
60: treated water storage tank 61: treated water discharge pipe
62: air inlet nozzle 63: pressure pump
64: fine bubble generator 65: fine bubble supply pipe
70: Membrane separator 80: Wastewater treatment plant

Claims (14)

A wastewater collecting tank 20 for collecting wastewater generated after the die casting process 10;
A chemical injector 40 for treating the wastewater transferred from the wastewater collecting tank 20;
A float separation device (50) for supplying bubble water to wastewater that has passed through the medicine injection device (40) to float and remove coagulated particles in the wastewater; And
A membrane separation device (70) for final treatment of the residual suspended material passing through the floating separation device (50);
Wherein the apparatus further comprises:
The method according to claim 1,
Wherein the chemical injector (40) is installed in a pipe connecting the waste water collecting tank (20) and the floating separator (50).
The method according to claim 1,
The chemical injector 40 includes a flocculant tank 41, a first ultrasonic device 42 and a first ultrasonic nozzle 43. The flocculant is connected to the waste water collecting tank 20 and the floating separator 50 Wherein the water is injected into a pipe for treating the die-casting washing wastewater.
The method of claim 3,
Wherein the flocculant is any one selected from the group consisting of aluminum sulfate, sodium aluminate, aluminum polychloride, ammonium alum, potassium alum, ferrous sulfate, ferric sulfate, and combinations thereof.
The method of claim 3,
The chemical injector 40 is characterized by injecting a coagulant composed of 2 to 4% liquid phase aluminum sulfate into a pipe connecting the wastewater collecting tank 20 and the floating separator 50 at a concentration of 1000 to 2500 ppm A device for treating diecasting wastewater.
The method of claim 3,
The chemical injector 40 further includes a flocculation aid tank 44, a second ultrasonic device 45 and a second ultrasonic nozzle 46. The flocculant tank 41 and the float separator 50 ) Is further injected into the pipe connecting the diecasting washing wastewater.
The method according to claim 6,
Wherein the coagulation aid is an organic polymer flocculant.
8. The method of claim 7,
Wherein the organic polymer flocculant is any one selected from the group consisting of starch, sodium alginate, glue, amine fulmarine, amine pyrrolidine, polyethyleneimine, polyacrylamide, sodium polyacrylate, and combinations thereof A device for treating diecasting wastewater.
8. The method of claim 7,
Characterized in that the chemical injector (40) injects the organic polymer flocculant into a pipe connecting the flocculant tank (41) and the floating separator (50) at a concentration of 40 to 60 ppm .
The apparatus according to claim 1, wherein the floating separation device (50)
A fine bubble generator 64;
A mixing tank 52 in which the micro-bubble supplied from the micro-bubble generator 64 and the wastewater passing through the drug injector 40 are mixed;
A float plate (53) tilted toward the top so that the coagulated particles agglomerated by the flocculant float by microbubbles;
A skimmer 55 for removing floated condensed particles;
A sludge storage tank 56 for storing the removed condensed particles;
A sludge discharge port 57 through which sludge is discharged; And
A treatment water tank (58) in which the condensed particle treated water is moved;
Wherein the apparatus for treating the die-casting washing wastewater comprises:
10. The method of claim 9,
Wherein the micro-bubble generator (64) generates micro-bubbles by a pressurizing pump.
10. The method of claim 9,
Wherein an average particle diameter of the fine bubbles supplied from the fine bubble generator (64) is 10 to 80 占 퐉.
10. The method of claim 9,
Wherein the time for which minute bubbles supplied from the microbubble generator (64) stays in the mixing tank (52) is 20 to 40 minutes.
A method for treating die-casting washing wastewater using the treatment apparatus of any one of claims 1 to 12.

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