KR101370246B1 - Purifing apparatus of acid mine drainage - Google Patents

Abstract

Disclosed is an acid mine wastewater purifier that allows for immediate discharge without the necessity of neutralizing the alkaline treated water while using a small amount of alkaline chemicals. The purifying apparatus includes: an oxidizing tank for supplying air or ozone to acid mine wastewater containing iron ions to oxidize iron ions and supplying an alkaline agent; An agglomeration tank for supplying a polymer to acid mine wastewater in which iron ions are oxidized to form flocs; A settling tank which precipitates the floc to produce sludge and discharge the supernatant to the outside; And a concentration tank for concentrating the sludge and discharging the supernatant to the outside. It includes, and transfers some of the concentrated concentrated sludge to the oxidation tank. According to this method, the pH of the oxidizing tank is lower than that of the related art, and some of the produced sludge is recycled as an adsorbent and a catalyst to improve the removal efficiency of iron ions, reduce the total sludge generation, and neutralize the discharged treated water. Can reduce the cost of equipment and chemicals.

Description

Purification of acid mine drainage {PURIFING APPARATUS OF ACID MINE DRAINAGE}

The present invention relates to an apparatus for purifying acid mine drainage, and more particularly, to an apparatus for purifying acid mine drainage, which enables to discharge immediately without using neutral chemicals and neutralizing alkaline treated water.

Acid Mine Drainage (hereinafter referred to as 'AMD') occurs in the mine shafts of hues and abandoned mines, and has a low pH as it passes through the surrounding rock layers and drains many metal ions, including iron and manganese ions. Means. In particular, the discharge of iron ions contained in AMD causes yellow river phenomena on the bottom of the river, which can cause not only destruction of aquatic ecosystems but also enormous adverse effects on human living environments.

There are two ways to treat AMD, physicochemical and natural purification. The natural purification method is used when the pollution concentration of mine drainage is not high, and the physicochemical treatment method is used when the concentration of AMD is serious.

The conventional physicochemical treatment method is mainly aimed at the removal of iron ions, and the main method is to remove the insoluble precipitate by operating the pH above 9.5. However, if the pH is operated above 9.5, the amount of neutralization chemicals is increased, and when the treated water is discharged, it is necessary to neutralize it again using acidic solution, which causes additional cost of facility and chemicals required for neutralization. .

Oxidation and contact methods have been proposed as methods for removing iron ions by water treatment according to water supply standards.

Iron removal by oxidizing method precipitates Fe ²⁺ with oxidizing agents such as chlorine, chlorine dioxide (ClO ₂ ) and potassium permanganate (KMnO ₄ ) to flocculate the precipitated particles by coagulation, and then separates them by coagulation sedimentation or sand filtration. That's how. However, the oxidizing method requires an oxidant chemical input facility, alkalinity due to oxidation is consumed, and the chemical cost of the alkali neutralizer and the oxidant chemical cost are incurred, and the installation cost of the backwashing facility and the filtering device by filtration is generated. there was.

In addition, the contact method is a method in which Fe ²⁺ is adsorbed on a contact as it is in an ionic state to oxidize adsorbed iron with an oxidant and separate by a self-catalyst. .

On the other hand, AMD containing Al ³⁺ ions elutes again in the form of aluminum hydroxide (Al (OH) ₄ ⁻ ) above pH 9.5 where the aggregation range of insoluble precipitate is pH 5.2 and Fe ⁺² ions form a completely insoluble precipitate. As a result, suspended solids (SS) in treated water increased, and the cost of alkali chemicals increased.

In order to solve the above-mentioned problems of the background art, the acid mine drainage purification device is capable of being immediately discharged without the need for neutralizing the alkaline treatment water without using much alkali chemicals supplied to the acid mine drainage containing iron ions. The purpose is to provide.

In addition, the present invention by the first step of removing the aluminum ions for the acid mine drainage containing aluminum ions, and the secondary process for removing the above-described iron ions can improve treatment efficiency and reduce the cost of drugs Another object is to provide a purification system for acid mine drainage.

An apparatus for purifying acid mine wastewater of the present invention for solving the above problems, comprising: an oxidizing tank for supplying air or ozone to an acid mine waste water containing iron ions to oxidize iron ions and supplying an alkali agent; An agglomeration tank for supplying a polymer to the acid mine wastewater in which the iron ions are oxidized to form a floc; A settling tank which precipitates the floc to produce sludge and discharges the supernatant to the outside; And a concentration tank for concentrating the sludge and discharging the supernatant to the outside. It includes, characterized in that for transporting some of the concentrated sludge to the oxidation tank.

Preferably, the alkaline agent is supplied such that the oxidizing tank is operated at pH 7.5 to 8.5.

Preferably, the concentrated sludge to be transferred to the oxidizing tank has a concentration of 50,000 mg / L to 300,000 mg / L, and 5 to 10% by weight of the acidic mine wastewater flowing into the oxidizing tank is conveyed.

Preferably, the primary reaction tank is supplied with an alkali chemicals to the acid mine wastewater containing aluminum ions before being supplied to the oxidation tank; A primary sedimentation tank for generating primary sludge from the acid mine wastewater in which the aluminum ions are oxidized and supplying treated water to the oxidation tank; A primary concentration tank for concentrating the primary sludge and discharging it to the outside and supplying supernatant water to the oxidation tank; . At this time, the alkali agent supplied to the primary reaction tank is supplied such that the primary reaction tank is operated at pH 5.2 to 6.5.

According to the purification apparatus of the acid mine drainage of the present invention, the following effects are obtained.

First, by reducing the pH of the acid mine drainage containing iron ions in the oxidizing tank as compared to the conventional one to reduce the equipment and chemical costs for the discharge of treated water discharged, and put the produced concentrated sludge back into the oxidizing tank adsorbent And it can be used as the oxidation catalyst can reduce the air supply capacity due to oxidation or reduce the amount of oxidant input.

Secondly, after removing the ion Al ³⁺ and Fe ³⁺ ions contained in the acid mine drainage primarily by purification treatment may be to prevent the outflow of the aluminum salt ions to achieve the improvement of the quality of the treated water, Al (OH) _3, Fe (OH) ₃ hydroxide can be used as a chemical to remove phosphorus in sewage treatment plants and as a raw material for the manufacture of flocculant.

1 is a graph showing the solubility of metal ions according to pH.
2 is a block diagram of a purification apparatus for removing iron ions according to the first embodiment of the present invention.
3 is a flowchart showing a purification process according to FIG. 2;
Figure 4 is a schematic diagram showing the metal ions adsorbed on the concentrated sludge.
5 is a block diagram of a purification apparatus including an additional process for removing aluminum ions according to a second embodiment of the present invention.
FIG. 6 is a flowchart showing a purification process according to FIG. 5. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1. Purification apparatus according to the first embodiment

2 and 3 are flowcharts showing the structure of the purification apparatus for removing iron ions according to the first embodiment of the present invention and the purification process thereof.

As shown in FIG. 2, the purification apparatus according to the first embodiment is mainly used to remove iron ions from acid mine drainage, and includes an oxidation tank 40, a mixing tank 50, a coagulation tank 60, and the like. It consists of a settling tank 70 and a concentration tank 80.

First, the oxidizer 40 is supplied with air or an oxidant to the lower side, Fe ²⁺ ions contained in the acid mine drainage Oxidized to Fe ³⁺ ions. At this time, the oxidation tank 40 is supplied with an alkaline agent such as NaOH or Ca (OH) ₂ and operated to have a pH of 7.5 to 8.5. In this case, when the pH is less than 7.5, Fe ²⁺ ions remain even after the oxidation reaction, so there is a problem in maintaining the insoluble state of the Fe (OH) ₂ hydroxide, and when the pH exceeds 8.5, the final discharge as described in the background art There is a burden on equipment and costs to neutralize the treated water.

1 is a graph showing the solubility of metal ions according to pH, Table 1 below shows the aggregation range of metal ions according to pH.

Coagulation range of metal ions according to pH Metal ion Settling pH (min) Other salt formation pH Sn 4.2 Fe (III) 4.3 Al 5.2 Pb (Ⅱ) 6.3 6.0 Cu (Ⅱ) 7.2 5.3 Zn 8.4 7.0 Ni 9.3 Fe (II) 9.5 CD 9.7 Mn (Ⅱ) 10.6

Unlike conventional purifiers, the pH is not operated above 9.5, which reduces the cost of alkali neutralization chemicals for the discharged treated water, and reduces the amount of sludge generated when alkali chemicals are used in the calcination cycle. And drug costs are reduced.

Next, the mixing tank 50 is stirred so that the alkali agent is well mixed with the acid mine drainage.

The agglomeration tank 60 forms a floc containing Fe ³⁺ ions by supplying a polymer to acid mine drainage mixed with an alkali chemicals.

The settling tank 70 precipitates flocs to produce sludge, and the supernatant is discharged to the outside.

Finally, the concentration tank 80 concentrates the sludge and discharges the supernatant water with the supernatant water of the settling tank 70. At this time, part of the concentrated sludge is dewatered, and the other part is transferred to the oxidation tank 40 into which the initial acid mine drainage is introduced.

The concentrated sludge transferred to the oxidizing tank 40 increases the iron ion removal efficiency as an adsorbent and a catalyst capable of adsorbing and oxidizing Fe ²⁺ ions by increasing the concentration of solids. The concentration of the concentrated sludge to be transported is preferably to be 50,000mg / L ~ 300,000mg / L. This is because when the concentration of the concentrated sludge to be transferred is too low, it does not act as an adsorbent and a catalyst, and when it is too high, clogging of the sludge conveying pipe occurs and a problem occurs in the operation of the sludge collector.

And it is preferable that the transfer amount is 5 to 10% by weight of the acid mine drainage flowing into the oxidation tank (40). This is because, if the transport amount is too small compared with the acid mine drainage, the sludge concentration of the oxidizing tank is formed too low, on the contrary, if the amount is too large, there is a problem in that the cost of power equipment and maintenance costs are high.

Since the concentrated sludge is in the form of hydroxides and other particulate bonds and has a viscosity, manganese ions and other metal ions can improve the treatment efficiency by acting as a sieving effect and an autocatalytic adsorbent through the concentrated sludge. Figure 4 is a schematic diagram showing the metal ions adsorbed in the concentrated sludge.

2. Purification apparatus according to the second embodiment

5 and 6 are flowcharts showing the structure of the purification apparatus for removing aluminum and iron ions according to the second embodiment of the present invention, and the purification process thereof.

As shown in FIG. 5, the purification apparatus according to the second embodiment mainly removes the iron ions from the acid mine drainage and then mainly removes the iron ions by the purification apparatus according to the first embodiment. In order to perform pretreatment before the acidic mine drainage is supplied to the oxidation tank 40 of the first embodiment, a primary reaction tank 10, a primary precipitation tank 20, and a primary concentration tank 30 are further provided. Here, the "primary" included in each component is to avoid confusion with the components of the first embodiment, it is clear that it is not defined with a separate 'secondary' configuration in mind.

First, the primary reactor 10 supplies an alkali agent to the acid mine drainage containing aluminum ions so that the Al ³⁺ ions form a hydroxide of Al (OH) ₃ . At this time, Fe ³⁺ ions are also removed while forming hydroxide of Fe (OH) ₃ .

As the alkali agent supplied to the first reaction tank 10, NaOH or Ca (OH) 2 is supplied, and the pH is preferably operated at 5.2 to 6.5. Drive as much as possible. This is because insoluble precipitates of aluminum ions are incompletely formed when the pH is less than 5.2, and Fe ²⁺ ions also form hydroxides when the pH is higher than 6.5, and some aluminum salt ions are generated.

The primary precipitation tank 20 precipitates insoluble Al (OH) ₃ and Fe (OH) ₃ hydroxides to produce primary sludge, and acid mine drainage from which the treated water Al ³⁺ ions and Fe ³⁺ ions are removed. ) Is supplied to the oxidation tank 40 according to the first embodiment.

The primary concentration tank 30 concentrates the primary sludge produced in the primary precipitation tank 20, and the supernatant water is supplied to the oxidation tank 40 together with the treated water of the primary precipitation tank 20. In this case, the produced primary concentrated sludge includes Fe (OH) _{3 in} addition to Al (OH) ₃ , and is used as a chemical for removing phosphorus, or dehydrated.

Oxidation tank 40, the treated water of the primary settling tank 20 from which Al ³⁺ ions and Fe ³⁺ ions have been removed and the supernatant of the secondary concentration tank 30 are introduced, and as described in the first embodiment, The oxidation of the hot water and the supply of alkali chemicals are performed.

Subsequent processes are performed in the mixing tank 50, the coagulation tank 60, the settling tank 70, and the concentration tank 80 similarly to the purification apparatus of the first embodiment, and the detailed processes are the same as in the first embodiment.

According to the second embodiment of the present invention, unlike the first embodiment, as Al ³⁺ ions and Fe ³⁺ ions are removed from the acid mine drainage, there are the following advantages.

First, as Al ³⁺ ions are first removed, neutralization drug costs can be reduced by preventing Al (OH) ₄ ⁻ generation. In addition, since Al (OH) ₄ ^- is not generated, it can be expected to improve treated water quality by reducing suspended solids.

Second, the presence of aluminum hydroxide is gelatinous to increase the concentration of the concentrated sludge in the thickening tank 80, according to the present invention by increasing the concentration of the concentrated sludge as Al ₃ ⁺ ions are first removed The treatment efficiency of the secondary process in the purification apparatus which comprises an Example can be improved.

Third, is the PO ₄ ^- to present in the water in the form inde main causative agent of eutrophication, of PO ₄ ^3- in the form of so forming the AlPO _4, FePO ₄ of the water-insoluble precipitate by Al ⁺ ₃ ions and Fe ³⁺ ions Primary sludge generated in the primary settling tank 2 can be utilized as a flocculant for removing phosphorus as a source of Al ³⁺ ions or Fe ³⁺ ions.

The foregoing has been described with reference to the embodiments of the present invention, but the scope of the present invention will extend to the technical spirit described in the claims and modifications or equivalents therefrom.

10: primary oxidation tank
20: primary precipitation precursor
30: primary concentration
40: oxidation tank
50: mixing tank
60: coagulation tank
70: sedimentation tank
80: thickening tank

Claims (5)

A purifier for purifying acid mine wastewater,
An oxidation tank for supplying air or ozone to acid mine wastewater containing iron ions to oxidize iron ions and supplying an alkaline agent;
An agglomeration tank for supplying a polymer to the acid mine wastewater in which the iron ions are oxidized to form a floc;
A settling tank which precipitates the floc to produce sludge and discharge the supernatant to the outside; And
A concentration tank for concentrating the sludge and discharging the supernatant to the outside; Lt; / RTI >
And a portion of the concentrated sludge is transferred to the oxidizing tank. The method of claim 1,
The alkaline agent is purified, acid mine drainage, characterized in that the oxidizing tank is supplied to be operated at pH 7.5 ~ 8.5. The method of claim 1,
Concentrated sludge to be transferred to the oxidizing tank,
Purification apparatus for acid mine wastewater having a concentration of 50,000 mg / L to 300,000 mg / L, 5 to 10% by weight of the acid mine waste water flowing into the oxidizing tank is transferred. The method of claim 1,
A primary reaction tank in which an alkaline agent is supplied to an acid mine wastewater containing aluminum ions before being supplied to the oxidation tank;
A primary sedimentation tank for generating primary sludge from the acid mine wastewater in which the aluminum ions are oxidized and supplying treated water to the oxidation tank;
A primary concentration tank for concentrating the primary sludge and discharging it to the outside and supplying supernatant water to the oxidation tank;
Purifier of acid mine waste water, characterized in that it further comprises. 5. The method of claim 4,
The alkaline agent supplied to the primary reaction tank, the acid mine wastewater purification apparatus, characterized in that the primary reactor is supplied to operate at pH 5.2 ~ 6.5.

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