KR101982701B1 - Apparatus and method for treatment of mixed acid wastewater containing hydrofluoric acid - Google Patents

Abstract

The present invention discloses an apparatus and method for treating mixed acid wastewater containing hydrofluoric acid. The apparatus for treating mixed acid wastewater containing hydrofluoric acid comprises: a heat exchanger receiving a cooling medium and performing heat-exchange on a dehydrated filtrate to lower a temperature of the dehydrated filtrate; a mixed acid wastewater diluting tank for diluting the mixed acid wastewater by receiving the dehydrated filtrate passing through the heat exchanger; a slaked lime dissolving tank for dissolving the slaked lime by receiving the dehydrated filtrate passing through the heat exchanger; and a dehydrated filtrate reservoir storing a filtrate separated from sludge while passing through a neutralization tank and a settling tank. The present invention has an effect of enhancing work safety and work environment.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrofluoric acid-containing mixed wastewater containing hydrofluoric acid,

The present invention relates to a hydrofluoric acid-containing mixed wastewater treatment apparatus and method for recycling molten slaked liquor dehydrated filtrate discharged from a mixed wastewater treatment plant containing hydrofluoric acid to a wastewater treatment plant as dilution water for hydrous lime and hydrofluoric acid mixed wastewater.

Hydrofluoric acid (Hydrofluoric Acid) is an aqueous solution of hydrogen fluoride (HF) which is a colorless irritant liquid. They are usually classified as highly toxic. At present, a large amount of waste water including hydrofluoric acid is generated due to process characteristics in the semiconductor, household electrical and electronic communication industries, steel making and processing industries, fertilizer and agricultural chemical manufacturing industries, FOSHAN manufacturing and fluorine use fluorine compound manufacturing industries. For example, fluorine is mainly used as an etching process and a cleaning agent in various industrial fields such as a semiconductor manufacturing process, an electronic component manufacturing process including an LCD, and a steelmaking process of an iron. In particular, fluorine is used in a semiconductor and steel- The number and generation of emission sources of hydrofluoric acid wastewater have greatly increased. In general, the fluoride content in industrial wastewater is known to be in the range of 30 to 200,000 ppm. Thus, the mixed wastewater containing hydrofluoric acid generated in the industrial field is discharged through neutralization treatment using powdered lime (or "lime"). Regarding the purification treatment of mixed acid wastewater containing hydrofluoric acid, Korean Patent Laid-Open Publication No. 10-2014-0101589 discloses a method for purifying zero hydrofluoric acid wastewater and a treatment facility for hydrofluoric acid wastewater using the same, And a method of treating wastewater. However, according to the existing fluorine-containing wastewater treatment technology, when the highly acidic mixed wastewater containing hydrofluoric acid is treated, excessive heat of reaction due to the injection of powdered calcium hydroxide and toxic gas and foam are generated, And environmental pollution due to untreated mixed wastewater discharge due to deterioration of neutralization treatment efficiency has become a problem. In addition, since the dehydrated filtrate collected in the dehydration of the calcium hydroxide (sludge) generated after the neutralization treatment is treated and discharged through a separate treatment plant, additional cost is required for discharge of the dehydrated solution, . As a result, it is possible to meet the safety requirements in the treatment of strongly acidic mixed wastewater containing hydrofluoric acid, prevent environmental pollution caused by the discharge of mixed wastewater, reduce the processing cost and water use due to dehydrated filtrate discharge, Is required for the treatment of mixed acid wastewater.

Patent Document 1: Korean Patent Laid-Open Publication No. 10-2014-0101589 (Publication date: August 20, 2014)

Patent Document 1: Korean Patent Publication No. 10-0960363 (registered on May 20, 2010)

One of the technical problems to be solved in the present invention is to secure an operational safety by controlling an explosive neutralization reaction in a mixed wastewater treatment including hydrofluoric acid.

One of the technical problems to be solved in the present invention is to improve the neutralization reaction efficiency of the mixed wastewater in mixed wastewater treatment including hydrofluoric acid.

One of the technical problems to be solved in the present invention is to prevent environmental pollution due to the discharge of mixed wastewater in mixed wastewater treatment including hydrofluoric acid.

One of the technical problems to be solved in the present invention is to reduce the operation cost by reducing the amount of slaked lime and process water by recycling the dehydrated filtrate in mixed wastewater treatment including hydrofluoric acid.

According to the present invention, there is provided a hydrofluoric acid-containing mixed wastewater treatment apparatus for neutralizing mixed wastewater by injecting slaked lime into a neutralization tank to which mixed wastewater has been introduced, characterized in that the cooling medium is supplied to heat- Lowering heat exchanger; A mixed wastewater diluting tank for diluting the mixed wastewater by receiving the dehydrating filtrate via the heat exchanger; A slaked lime dissolving tank for dissolving the slaked lime by being supplied with a dehydrating filtrate through the heat exchanger; And a dehydrated filtrate reservoir storing the filtrate separated from the sludge while passing through the neutralization tank and the settling tank.

According to an embodiment of the present invention, the settling tank may have a cooling jacket through which the cooling water cooled from the cooling device flows.

According to an embodiment of the present invention, the heat exchanger may be configured to be connected to a cooling medium circulation flow path, one end of which is connected to a cooling medium transfer path connected to the cooling device, and the other end of which is connected to a cooling medium circulation path for withdrawing the heat- .

According to the embodiment of the present invention, the dehydrated filtrate storage tank includes a dehydrated filtrate supply line connected to a dehydrated filtrate supply line through which the stored dehydrated filtrate is passed through a heat exchanger, and a dehydrated filtrate first supply line And a dehydrating filtrate second supply line for supplying dehydrated filtrate, which is heat-exchanged through the heat exchanger, to the slaked liquor dissolution tank.

According to the present invention, there is provided a hydrofluoric acid-containing mixed wastewater treatment method for neutralizing mixed wastewater by introducing hydrated lime into a neutralization tank into which a mixed wastewater has been introduced to induce a neutralization reaction, A heat exchange step of lowering the temperature of the dehydrated filtrate; Diluting the mixed wastewater to dilute the mixed wastewater by supplying the dehydrating filtrate via the heat exchanger to the mixed wastewater dilution tank; A lime lime dissolving step of liquefying and liquefying the slaked lime by receiving a dehydrating filtrate through the heat exchanger; And a dehydrating filtrate storing step of storing the filtered water separated from the sludge while passing through the neutralization tank, the cooling tank, and the settling tank.

According to an embodiment of the present invention, it is possible to induce cooling and further neutralization reaction in the settling tank after the neutralization reaction.

The present invention solves the problem that an excessive amount of calcium hydroxide is generated due to the excessive amount of powdered calcium hydroxide during the treatment of hydrofluoric acid mixed wastewater due to the use of the low concentration mixed wastewater and the low concentration liquid calcium hydroxide and the explosive neutralization It is possible to reduce the generation of high temperature and toxic gas according to the reaction, thereby improving work safety and working environment.

INDUSTRIAL APPLICABILITY The present invention has an effect of preventing environmental pollution due to indiscriminate discharge of filtered water after mixed wastewater treatment.

The present invention can reduce the amount of chemical used, reduce the amount of calcium hydroxide produced after neutralization reaction, and reduce the amount of dehydrated liquor It is possible to reduce the input cost of the process water and the additional treatment cost, and drastically reduce the maintenance cost in the hydrofluoric acid mixed wastewater treatment.

1 is an example of a block diagram for explaining a mixed acid wastewater treatment process through a conventional hydrofluoric acid mixed wastewater treatment apparatus.
2 is a block diagram illustrating a mixed acid wastewater treatment process using a hydrofluoric acid-containing mixed wastewater treatment apparatus according to an embodiment of the present invention.
3 is an example of a mixed system wastewater treatment system of a hydrofluoric acid-containing mixed wastewater treatment apparatus according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an apparatus and method for treating hydrofluoric acid-containing mixed wastewater according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In the term used in the description of the present invention, 'mixed wastewater (W1)' may mean 'wastewater containing hydrofluoric acid'. 'Dehydrated filtrate (W2)' may mean 'water' separated from sludge.

In general, filtration treatment of mixed wastewater through hydrofluoric acid mixed wastewater treatment system is treated to induce neutralization reaction using calcium hydroxide (Ca (OH) ₂ ). In order to neutralize the mixed wastewater, NaOH and Na ₂ CO ₃ can be added as an additive to neutralize while increasing the treatment efficiency. Here, the neutralization may be a reaction in which an acid and a base react to form a salt and water.

1 is an example of a block diagram for explaining a mixed acid wastewater treatment process through a conventional hydrofluoric acid mixed wastewater treatment apparatus.

As shown in FIG. 1, the conventional hydrofluoric acid mixed wastewater treatment apparatus includes a mixed wastewater inflow tank, a neutralization tank, and a settling tank into which the mixed wastewater W1 is introduced, and a three-stage treatment process And is designed to neutralize the mixed wastewater W1.

In the treatment of the mixed wastewater, the lime is added to the neutralization tank to cause the neutralization reaction. The high concentration sludge (SW, sludge) generated in the treatment process is sent to the sludge storage tank to be taken out and the treated water collected through the settling tank is discharged .

Such a conventional mixed acid wastewater treatment apparatus with hydrofluoric acid can be loaded with an excessive amount of powdered calcium hydroxide at a high concentration. If excessively high amount of powdered calcium hydroxide is injected into the neutralization reaction tank, it may cause heat of reaction and explosion at a high temperature, and toxic gas and foam may be generated, thereby deteriorating the working environment, failing to satisfy work safety, It can cause secondary environmental pollution due to the discharge of untreated mixed wastewater. In addition, since the treated water (W2), which is a dehydrated filtrate collected in dehydration of the sludge generated after the neutralization treatment, is treated and discharged through a separate treatment plant, an additional cost is required for discharging the dehydrated solution. .

The present invention relates to a method and apparatus for controlling an explosion neutralization reaction in hydrofluoric acid-containing mixed wastewater treatment to secure work safety, improve the neutralization reaction efficiency of mixed wastewater, prevent environmental pollution due to discharge of untreated mixed wastewater, To reduce the amount of lime and process water used, thus effectively reducing the overall operation cost for mixed wastewater treatment.

The hydrofluoric acid mixed wastewater treatment apparatus 100 according to the embodiment of the present invention can be constructed as shown in FIGS.

2 is a block diagram illustrating a mixed acid wastewater treatment process using a hydrofluoric acid-containing mixed wastewater treatment apparatus according to an embodiment of the present invention. 3 is an example of a mixed system wastewater treatment system of a hydrofluoric acid-containing mixed wastewater treatment apparatus according to an embodiment of the present invention.

The acidic wastewater (hereinafter also referred to as 'mixed wastewater W1') generated at various industrial sites is neutralized through the mixed wastewater treatment apparatus 100 according to the embodiment of the present invention, The dehydrated filtrate is recycled to the process water, and the sludge can be treated to be collected and taken out separately.

The hydrofluoric acid-containing mixed wastewater treatment apparatus according to the embodiment of the present invention is configured to neutralize the mixed wastewater by injecting calcium hydroxide into the neutralization tank 106 into which the mixed wastewater W1 has been introduced, A mixed wastewater dilution tank 103 for diluting the mixed wastewater W1 supplied with the dehydration filtrate W2 via the heat exchanger 102, a heat exchanger 102 for reducing the temperature of the dehydrated filtrate by heat exchange with the mixed wastewater W1, A slaked lime solenoid tank 105 which is supplied with a dehydrating filtrate W2 through the vessel 102 to dissolve the slaked lime and a dehydrated filtrate 105 for storing filtered water separated from the sludge while passing through the neutralization tank 106 and the cooling / And a storage tank 109. [

The cooling / settling tank 107 may be configured with a cooling jacket through which the cooling water of the cooling device 110 flows.

The heat exchanger 102 may be configured to be connected to a cooling medium circulation channel for one end connected to the cooling medium transfer path connected to the cooling device 110 and the other end for collecting the heat-exchanged cooling medium and sending the same to the cooling device.

The dehydrated filtrate storage tank 109 is connected to a dehydrated filtrate water supply line through which the stored dehydrated filtrate W2 is passed through a heat exchanger and is connected to a mixed wastewater dilution tank 103 through a heat exchanger 102, And a dehydrating filtrate second supply line for supplying the dehydrated filtrate W2 heat-exchanged through the first dehydrating filtrate first supply line and the heat exchanger 102 to the slaked liquor dissolution tank 105 may be connected.

Here, the reference character 'P' is a pump. 'V' is a valve. The valve V may include an electromagnetic valve capable of opening and closing the flow rate and the fluid flow with an electric signal. The on / off switching control of the valve V can be controlled by a controller such as a microcontroller (not shown).

The hydrofluoric acid-containing mixed wastewater treatment method according to the embodiment of the present invention is characterized in that hydrofluoric acid-containing mixed wastewater (W2) which neutralizes the mixed wastewater W2 by introducing calcium hydroxide into the neutralization tank 106 into which the mixed wastewater W2 has been introduced, A method for treating wastewater, comprising the steps of: a heat exchange step of supplying a cooling medium in a heat exchanger (102) and heat-exchanging a dehydration filtrate (W2) to lower the temperature of a dehydration filtrate; a dehydrating filtrate (W2) passing through a heat exchanger A mixed liquor wastewater dilution step of diluting mixed liquor wastewater supplied from the liquor tank 103, a lime liquification step of liquifying and liquefying the slaked liquor supplied with the dehydrating liquor W2 via the heat exchanger 102, And a dehydrating filtrate storing step of storing the dehydrating filtrate W2, which is filtered water separated from the sludge SW, through the settling tank 107.

And cooling and further neutralization reaction in the cooling / settling tank 107 after the neutralization reaction.

The dehydrated filtrate W2 generated in the hydrated lime slurry dewatering apparatus 108 is stored in the dehydrated filtrate storage tank 109 and then cooled to 50 ° C or lower through the heat exchanger 102 to remove the mixed wastewater dilution tank 103 and / The dilution of the liquid slaked lime and the mixed wastewater which is recycled as the dilution process water to the slaked lime melting tank 105 reduces the amount of the powdered lime slurry and reduces the explosive chemical reaction and improves the reaction efficiency by cooling the slaked lime slurry, Followed by dewatering.

The slaked lime dissolving tank 105 is installed before the addition of the powdered sludge and the slaked powdered slaked lime of the strong alkali is made into a liquid slaked lime having a low concentration by using the slaked lime fractionated water filtrate W2. (W2) to dilute the hydrated lime mixed wastewater with acidic wastewater having a low concentration, a step of neutralizing the liquid alkaline lime and diluted weak acid mixed wastewater in the neutralization tank (106) And a step of controlling the heat generated by the alkaline reaction through the jacket type cooling / settling tank 107, thereby minimizing the risk of the operator by weak acid and weak alkali neutralization reaction, and dramatically reducing the amount of water used, It is possible to solve the increase in the amount of wastewater and to stably and efficiently treat the mixed wastewater.

2 and 3, the main part of the hydrofluoric acid-containing mixed wastewater treatment apparatus 100 according to the embodiment of the present invention includes a heat exchanger 102, a mixed wastewater dilution tank 103, a slurry storage tank 104, A lime lime melting tank 105, a neutralization tank 106, a cooling / settling tank 107, a dehydrating filtrate storage tank 109, and a cooling device 110.

The heat exchanger 102 is supplied with the heat exchange cooling medium (cooling water or the like) cooled from the cooling device 110 through the cooling medium transfer path L 1 and the high temperature dehydration filtrate W 2 recycled as the process water in the present invention, Thereby lowering the temperature of the dehydrating filtrate W1 and supplying the mixed wastewater to the mixed wastewater dilution tank 103 and the slaked liquor dissolution tank 105.

One end of the heat exchanger 102 is connected to the cooling medium transfer path L1 connected to the cooling device 110 and the other end is connected to the cooling medium circulation path L2 for collecting the heat- As shown in FIG.

A dehydrated filtrate supply line W2-D2 for passing the dehydrating filtrate W2 stored in the dehydrated filtrate storage tank 109 to the heat exchanger 102 by the pumping force of the pump P1 is provided around the heat exchanger 102, L1 through the heat exchanger 102 and the dehydrated filtrate first supply line W2-L2 for supplying the dehydrated filtrate W2 heat-exchanged through the heat exchanger 102 to the mixed wastewater dilution tank 103 and the heat exchanger 102 A second dehydrating filtrate supply line W2-L3 for supplying a heat-exchanged dehydrating filtrate W2 to the slaked liquor dissolution tank 105 is opened to use the dehydrated filtrate W2 as a diluting water for mixed mixed wastewater or to dissolve slaked liquor And a flow path for recycling as water.

The mixed wastewater dilution tank 103 is supplied with the dehydrated filtrate W2 which has been lowered as the process water to dilute the mixed wastewater W1 at a high concentration at a low concentration through the first dehydrating filtrate supply line W2- And may be configured to dilute the wastewater W1 at a low concentration.

The concentrated mixed wastewater W1 containing hydrofluoric acid is introduced into the mixed wastewater dilution tank 103 by the mixed wastewater transfer pump 101 under the condition that the liquid dehydration filtrate W2 is accommodated in the mixed wastewater dilution tank 103 May be diluted to a low concentration at a high concentration and then be advantageous to activate the neutralization reaction process.

The slaked lime storage tank 104 is equipped with a feed screw S for receiving or storing the slaked lime (Ca slurry (Ca (OH) ₂ ) in a solid phase or a powder phase and transporting the slaked lime taken out to the slaked lime melting tank 105 .

The slaked liquor dissolution tank 105 can be dissolved in the liquefied state over time when the slaked liquor is introduced by the conveying screw S under the condition that the dehydrated filtrate W2 is accommodated. To this end, the present invention can supply the low-temperature dehydrating filtrate (W2) recycled to the process water through the second supply line (W2-L3) and promote the dissolution of the calcium hydroxide without supplying additional external process water.

The neutralization tank 106 is connected to a mixed wastewater supply line W1-L1 for supplying mixed wastewater whose dilution has been completed from the mixed wastewater dilution tank 103 at one end and dissolved at the other end from the slaked lime dissolution tank 105, The mixed liquor wastewater W1 supplied from the mixed liquor wastewater supply line W1-L1 and the lime lime supply line W1-L2 is connected to the slaked liquor supply line W1- Thereby inducing a reaction.

In the neutralization reaction in the neutralization tank 106, for example, mixed liquor diluted 3 to 5 times in accordance with the hydrofluoric acid concentration of the mixed liquor wastewater W1 and liquefied liquified solids dissolved in consideration of the mixed- And the hydrated lime can be generated by the neutralization exothermic reaction and the hydration reaction as shown in the following reaction scheme [1.2] to be removed in the form of a precipitate.

[Reaction Scheme 1] Basis of mixed wastewater items Reaction formula

Ca ²⁺ + _2F- CaF ₂ ↓

Ca ²⁺ + 2Cl ^- CaCl ₂ ↓

Ca ²⁺ + 2NO ₃ ^- - Ca (NO ₃ ) ₂ ↓

Ca ²⁺ + SO ₄ ^2- CaSO ₄ ↓

[Reaction formula 2] Calcium hydroxide (Ca (OH) ₂ and hydrofluoric acid (HF)

Ca (OH) ₂ + 2HF? CaF ₂ ↓ + 2H ₂ O

The precipitated high-temperature slaked lime components are transferred to the cooling / sedimentation tank 107. At this time, the temperature of the cooling / settling tank 107 can be cooled from about 70 to 75 DEG C to 60 DEG C or less by the cooling water supplied from the cooling device 110 along the cooling line L3.

At this time, in the neutralization tank 106, the addition of the unreacted mixed wastewater (W1) and the addition of slaked lime lead to the precipitation / concentration of the hydrated lime. In this process, neutral pH (6.5-7.5) can be adjusted to about 25% NaOH in the neutralization tank (106) and the cooling / precipitation tank (107) for pH neutralization of strong acid mixed wastewater.

The concentrated slaked lime fractions are transferred to a dewatering unit 108 to be separated into a dewatering cake sludge SW and a filtrate water dewatering filtrate W2 and a sludge SW having a water content of less than about 60% And the dehydrated filtrate W2 which is the separated filtrate is transferred to the dehydration filtrate reservoir 109 and can be recycled as the liquefaction liquification of the slaked liquor and the dilution process water for the strong acid mixed wastewater W2.

The mixed mixed wastewater treatment process through the hydrofluoric acid mixed wastewater treatment apparatus 100 according to the present invention will be described with reference to FIGS. 2 and 3. FIG.

The mixed wastewater W1 containing a high concentration of hydrofluoric acid is transferred to the mixed wastewater dilution tank 103 through the mixed wastewater transfer pump 101 and then the lime is removed from the lime storage tank 104, (105).

The slaked liquor dissolved in the slaked lime dissolving tank 105 is supplied to the mixed liquor wastewater neutralization tank 106 and neutralized through the mixed liquor wastewater neutralization tank 106 to the mixed wastewater W1 flowing out from the mixed liquor dilution tank 103. At this time, in order to promote and stabilize the neutralization reaction, NaOH (caustic soda) can be removed from the NaOH storage tank 111 and supplied to the mixed acid waste water neutralization tank 106.

Here, the concentration of the calcium hydroxide supplied to the mixed wastewater neutralization tank 106 affects the neutralization treatment operation safety and the neutralization treatment efficiency. For example, when an excessive amount of high-concentration powdered calcium hydroxide is injected, the working environment may deteriorate due to the generation of reaction heat at high temperatures, explosion, toxic gas, foam, etc., And the liquefied low-concentration lime is fed to the mixed wastewater neutralization tank 106 to lower the heat of the high temperature reaction during the neutralization reaction, And bubble generation effectively.

The treated water of the mixed wastewater W1 neutralized through the mixed wastewater neutralization tank 106 is separated into filtrate and sludge by cooling precipitation through the cooling / settling tank 107 and is introduced into the dehydration apparatus 108. The treated water flowing into the dewatering device 108 is separated and recovered by the dewatering filtrate W2 and the sludge SW while being dehydrated. The sludge SW to be recovered can be collected in the sludge storage 112 and taken out to the outside by a conveying means such as a vehicle.

On the other hand, the dehydrated filtrate W2, which is filtered water, is not discharged as it is and is stored in the dehydrated filtrate reservoir 109, and if necessary, dissolving water used for dissolving the powdery calcium hydroxide at a low concentration, or dilution required for diluting the mixed wastewater W1 Thereby enabling operation of the mixed wastewater treatment apparatus 100 without supplying water separately.

The dehydrated filtrate W2 stored in the dehydrated filtrate storage tank 109 is pumped by the feed pump P1 and is introduced to the mixed wastewater dilution tank 103 and the slaked liquor dissolution tank 105 via the heat exchanger 102. [

The dehydrating filtrate W2 supplied to the mixed wastewater dilution tank 103 and the slaked liquor dissolution tank 105 is first passed through the heat exchanger 102 in the water supply process.

The temperature of the dehydrating filtrate W2 is lowered through the heat exchanger 102. The temperature of the dehydrating filtrate W2 supplied to the mixed wastewater dilution tank 103 and the slaked liquor dissolution tank 105 is supplied by the heat exchanger 102 in a state of low temperature.

For example, when the mixed liquor wastewater W1 is subjected to a neutralization reaction by introducing slaked liquor into the mixed liquor wastewater W1 for neutralization treatment, the temperature of the mixed liquor wastewater W1 rises up to about 80 ° C., The temperature of the dehydrating filtrate W2 separated from the swirling flow SW is cooled while passing through the heat exchanger 102 and is supplied to the mixed wastewater dilution tank 103 and the suicide lysis tank 105 simultaneously It is possible to control the temperature of the mixed wastewater W1 during the neutralization reaction according to the addition of the hydrated lime.

The dehydrated filtrate W2 obtained from the dehydrator 108 is first stored in the dehydrated filtrate storage tank 109 and then cooled to about 50 캜 or lower at an initial temperature of about 80 캜 after passing through the heat exchanger 102, The filtrate W2 is transferred to the mixed wastewater dilution tank 103 to dilute the high concentration mixed wastewater W1 with about 3 to 5 times the diluted mixed wastewater W1.

The powdery slaked lime stored in the slaked lime storage tank 104 is transferred to the slaked lime dissolving tank 105 through the conveying screw and supplied to the slaked lime dissolving tank 105 while passing through the heat exchanger 102 and having a lowered temperature The lime is dissolved in the liquid phase.

The low concentration mixed wastewater diluted in the mixed wastewater dilution tank 103 flows into the neutralization tank 106 and the liquid lime hydrate dissolved in the slag lysis tank 105 flows into the neutralization tank 106 in accordance with the low concentration mixed wastewater concentration And the mixed acid is precipitated through the neutralization reaction.

The mixed wastewater and the slaked lime mixture according to the neutralization reaction are transferred to the cooling / settling tank 107 through the pump P2. In the cooling / sedimentation tank 107, the temperature of the mixed wastewater and the slaked lime mixture is lowered as a whole through the cooling water of the cold water, which is the cooling medium supplied from the cooling device 110, and the additional secondary neutralization reaction and the neutralization reaction Thereby precipitating the resulting mixture.

The precipitated mixture is transferred to the dehydrator 108 to separate the sludge SW, which is solid in the mixture, from the dehydrating filtrate W2, which is filtrate. The separated solid phase sludge SW is transferred to a landfill through a delivery facility and the dehydrated filtrate W2, which is filtrate, can be flown and stored in the dehydrated filtrate reservoir 109.

The dehydrating filtrate W2 flowing into the dehydrated filtrate storage tank 109 is supplied to the mixed wastewater dilution tank 103 and the slaked liquor dissolution tank 105 at any time without introducing the new process water to promote dilution of the mixed wastewater and dissolution of the slaked lime As a process water.

As described above, the present invention is directed to a method and apparatus for converting an excess amount of calcium hydroxide into a mixed wastewater dilution and a low concentration liquid lime by the excessive chemical injection during the injection of powdered calcium hydroxide, The risk and the amount of hydrated lime were minimized, and the unreacted hydrocarbons and liquid lime were further reacted with cooling in the cooling / settling tank to increase the efficiency of the mixed acid removal. In addition, there is an advantage in that the existing process water using the tap water as the process water is generally used as the process water by recycling the slaked lime dehydrated filtrate to prepare for environmental pollution, and to reduce the disposal cost and maintenance cost of the mixed waste water.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, .

101: Mixed wastewater transfer pump 102: Heat exchanger
103: mixed wastewater dilution tank 104: slaked lime storage tank
105: slaked liquor dissolution tank 106: neutralization tank
107: Cooling / settling tank 108: Dewatering device
109: dehydrated filtrate storage tank 110: cooling device
111: NaOH storage tank

Claims (6)

A hydrofluoric acid-containing mixed wastewater treatment apparatus for neutralizing mixed wastewater by introducing calcium hydroxide into a neutralization tank into which mixed wastewater has been introduced,
The other end of the cooling medium is connected to the cooling medium transfer path connected to the cooling device and the other end is connected to the cooling medium circulation path for withdrawing the heat-exchanged cooling medium to the cooling device so that the cooling medium is supplied and the dehydrated filtrate is heat- Lowering heat exchanger; A mixed wastewater diluting tank for diluting the mixed wastewater by receiving the dehydrating filtrate via the heat exchanger; A slaked lime dissolving tank for dissolving the slaked lime by being supplied with a dehydrating filtrate through the heat exchanger; And
And a dehydrated filtrate reservoir for storing filtrate separated from the sludge while passing through the neutralization tank and the settling tank. The method according to claim 1,
Wherein the settling tank has a cooling jacket through which the cooling water of the cooling device flows. delete The method according to claim 1,
The dehydrated filtrate storage tank includes a dehydrated filtrate first supply line connected to a dehydrated filtrate supply line through which a dehydrated filtrate is passed through a heat exchanger, a dehydrated filtrate first supply line through which the dehydrated filtrate subjected to heat exchange through the heat exchanger is supplied to a mixed acid waste water dilution tank, And a dehydrating filtrate second supply line for supplying the dehydrated filtrate to the slaked liquor dissolution tank is connected. A mixed hydrofluoric acid wastewater treatment method for neutralizing a mixed wastewater by introducing hydrated lime into a neutralization tank into which a mixed wastewater has been introduced to induce a neutralization reaction,
A cooling medium is supplied from a heat exchanger connected to a cooling medium circulation channel for once sending the cooling medium to the cooling device, and the other end is connected to a cooling medium transfer path connected to the cooling device, and the dehydrated filtrate is heat- A heat exchange step of lowering the temperature; Diluting the mixed wastewater to dilute the mixed wastewater by supplying the dehydrating filtrate via the heat exchanger to the mixed wastewater dilution tank; A lime lime dissolving step of liquefying and liquefying the slaked lime by receiving a dehydrating filtrate through the heat exchanger; And
And a dewatering filtrate storing step of storing filtered water separated from the sludge while passing through the neutralization tank and the cooling tank and the settling tank. 6. The method of claim 5,
And cooling and further neutralization reaction in the settling tank after the neutralization reaction.

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