KR101898801B1 - PASSIVE TREATMENT SYSTEM OF ACID MINE DRAINAGE INCLUDING HIGH CONCENTRATION Mn - Google Patents

Abstract

The present invention relates to a natural purification treatment system for acid mine drainage.
The natural purification treatment system according to the present invention is a natural purification treatment system which is capable of receiving mine drainage and improving the pH of the mine drainage discharged from the oxidation sedimentation tank and oxidizing sedimentation tank where the metal in the mine drainage is oxidized and settled, , Mixed with limestone and slag, mixed with mine drainage discharged from SAPS tank, mixed with manganese in mine drainage form oxide or hydroxide form, and mine drainage discharged from mixed reaction tank, And a wastewater which is downwardly adjusted in accordance with the discharge standard.

Description

TECHNICAL FIELD [0001] The present invention relates to a system for treating a mine drainage containing high-concentration manganese,

The present invention relates to a purification system for acidic mine drainage discharged from abandoned mines, and more particularly to an acidic mine drainage natural purification system for naturally purifying water without using power.

The environmental problems caused by the abandoned and abandoned mines include soil subsidence, river burial due to loss of waste seepage and mineral debris, heavy metal pollution in the soil, water runoff from drainage and waste seepage, and water pollution from mineral leachate leachate. In particular, the problem of water pollution by acidic mine drainage from underground coal mine tailings piles has started to become very serious since the mid 1990s.

Acid mine drainage is formed by oxidation of sulfide minerals such as pyrite (FeS ₂ ) and white iron (FeS) exposed to the atmosphere by reacting with oxygen and water, and it is acidic due to its low pH, and iron, aluminum, manganese It is characterized by high heavy metal content.

These acidic mine drainage is a contaminant in itself, but it releases and migrates the surrounding heavy metals due to its low pH, thereby destroying the aquatic ecosystem by polluting the surrounding surface and groundwater. In addition, the metal ions in the mine drainage are oxidized and precipitated as metal hydroxide such as Fe (OH) ₃ , resulting in a sediment of yellow color or white on the bottom of the river, thereby deteriorating the beauty.

The purification method of acidic mine drainage is divided into active treatment and passive treatment. Aggressive treatment methods include pH control, coagulation, filtration, and precipitation using a neutralizing agent. Typical active treatments include reverse osmosis, ion exchange, and electrodialysis. However, this aggressive treatment method has a high treatment efficiency, but there is a problem that the maintenance cost is high due to the continuous input of chemicals, manpower, and power. Therefore, the passive treatment method in which the investment cost and the maintenance cost are much less than the active treatment method, It is widely used.

These passive treatment methods include neutralization treatment methods using limestone such as anoxic limestone drains (ALDs) and oxydi limestone drains (OLD), aerobic and anaerobic artificial waters, and successive alkalinity-producing systems (SAPS) or RAPS . The configuration of the SAPS in this passive treatment method is shown in Fig.

Referring to FIG. 1, the SAPS system comprises a large puddle tank 2 on the discharge path of acid mine drainage, a limestone layer L on the bottom of the tank 2, a limestone layer L The organic layer O is stacked. The organic material layer O is filled with an organic material composed of carbon, hydrogen, and oxygen. Organic materials include mushroom compost.

In the SAPS system having the above-described structure, the acidic mine drainage is discharged from the tunnel M to the outside (P, W), flows into the upper part of the SAPS system, and flows downward along the vertical direction. That is, the acid mine drainage flows into the limestone layer L through the organic material layer O and is discharged along the conduit T connected to the limestone layer L. The acidic mine drainage is neutralized by the limestone layer (L) and the metabolism of the microorganisms carried on the organic layer (O) during the passage through the SAPS system.

In the SAPS system, the mine drainage with improved alkalinity is oxidized and precipitated in the settling tank placed at the rear stage, and heavy metals are removed. Of course, even in the SAPS bath (2), the heavy metals in mine drainage are combined with dissolved oxygen to form metal (water) oxides and precipitate as shown in the following reaction formula.

In the SAPS system, the anaerobic environment is consumed by consuming oxygen from the organic layer, and the alkalinity is supplied by the limestone layer. In the mine drainage with improved alkalinity, the metal (ox) oxide (S) is formed in the sedimentation tank or the like disposed in the subsequent stage to remove the metal as shown in the following reaction formula

4Fe ²⁺ + O ₂ + 4H ^{+ -} > 4Fe ³⁺ + 2H ₂ O

Fe ³⁺ + 3H ₂ O? Fe (OH) ₃ (s) + 3H ⁺

Acidic mine drainage varies depending on the nature, but it contains a lot of iron, aluminum and manganese. Iron and aluminum are precipitated as oxides in the pH condition of SAPS (pH 7 ~ 8), but as manganese is precipitated as oxides in pH 9 and above, the concentration of manganese in the mine drainage is high There is a problem that the treatment is difficult.

It is an object of the present invention to provide a system for naturally purifying an acidic mine drainage containing manganese at a high concentration.

On the other hand, other unspecified purposes of the present invention will be further considered within the scope of the following detailed description and easily deduced from the effects thereof.

To achieve the above object, there is provided a natural purification system for mine drainage including high-concentration manganese according to the present invention.

A natural purification treatment system according to a first aspect of the present invention includes: an oxidation sedimentation tank that receives mine drainage and oxidizes and deposits metal in mine drainage; A SAPS tank in which the pH of the mine drainage discharged from the oxidation settling tank is improved and the metal in the mine drainage is oxidized and settled; A mixing tank filled with a mixture of limestone and slag and containing mine drainage discharged from the SAPS tank and precipitating manganese in mine drainage in the form of oxide or hydroxide; And a marsh that receives the mine drainage discharged from the mixing tank and downs the pH of the mine drainage to meet the discharge standard.

In this embodiment, it is preferable that the mixing tank mixes limestone and slag at a volume ratio of 1: 1 to 1: 0.7, the limestone has a particle size of 3 to 5 cm, and the slag has a particle size of 2 to 6 mm. Here, the slag is preferably a cold-rolled steelmaking slag.

According to this embodiment, it is preferable that the mixing tank is formed with an inlet port at the lower portion and an outlet port formed at the upper portion so that the mine drainage flows from the lower portion to the upper portion.

A natural purification treatment system according to a second aspect of the present invention includes: an oxidation sedimentation tank containing mine drainage and oxidizing and precipitating metal in a mine drainage; A pH of the mine drainage discharged from the oxidation settling tank is improved, a heavy metal in mine drainage including manganese is oxidized and settled, a lower limestone layer is mixed with limestone and slag, and an improved SAPS article; A sedimentation tank containing manganese drainage discharged from the modified SAPS tank and precipitating heavy metals in mine drainage, including manganese, in the form of oxides or hydroxides; And a marsh that receives the mine drainage discharged from the settling tank and downs the pH of the mine drainage to meet the discharge standard.

In the present embodiment, the modified SAPS tank mixes limestone and slag in a volume ratio of 1: 1 to 1: 0.7, preferably, the limestone has a particle size of 3 to 5 cm and the slag has a particle size of 2 to 6 mm. Here, the slag is preferably a cold-rolled steelmaking slag.

Particularly, in the present embodiment, it is preferable that the size of the improved SAPS tank is such that the mine drainage can stay at least one day.

According to the present invention, there is an advantage that manganese can be removed from the mine drainage containing high concentration of manganese and the mine drainage can be neutralized.

In the present invention, iron and aluminum, which are competitive ions of manganese, are oxidized and precipitated in the oxidation and precipitation tank and SAPS tank, and manganese in the mine drainage is oxidized and precipitated in the mixing tank by increasing the pH to 9.0 or more using slag . In particular, in the mixed reaction tank, oxidation and precipitation of manganese can be maintained even when the pH is 9 or less due to the autocatalytic action of manganese precipitated in hydroxide form.

In addition, in the present invention, there is an advantage that the problem of narrowing the site where the natural purification facility is installed can be solved by installing the improved SAPS tank.

On the other hand, even if the effects are not explicitly mentioned here, the effect described in the following specification, which is expected by the technical features of the present invention, and its potential effects are treated as described in the specification of the present invention.

1 is a schematic diagram for explaining a conventional SAPS system.
2 is a schematic diagram of a natural purification processing system according to the first embodiment of the present invention.
3 is a schematic diagram of a natural purification processing system according to a second embodiment of the present invention.
FIGS. 4 and 5 are graphs showing the purification efficiency (water quality-FIG. 8, manganese removal-FIG. 9) in each tank when the horizontal flow is applied in the series 1 (Example 1).
FIGS. 6 and 7 are graphs showing the purification efficiency (water quality change-FIG. 10, manganese removal-FIG. 11) in each group when vertical upward flow is applied in the series 1 (Example 1).
8 is a graph showing changes in water quality per unit process in the second embodiment (second embodiment).
9 is a graph showing manganese removal rates according to mine drainage retention time in SAPS2 in the series 2 (second embodiment).
10 is a graph showing the heavy metal removal rate of the mixed reaction tank in the series 1 to which the horizontal flow is applied.
11 is a graph showing the removal rate of heavy metals in the mixing tank in Series 1 to which vertical flow is applied.
12 is a graph showing the heavy metal removal rate of SAPS2 in the series 2.
* The accompanying drawings illustrate examples of the present invention in order to facilitate understanding of the technical idea of the present invention, and thus the scope of the present invention is not limited thereto.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the present invention.

Hereinafter, a natural purification treatment system for mine drainage containing high-concentration manganese (hereinafter referred to as a "natural purification treatment system") according to the first embodiment of the present invention will be described in more detail.

2 is a schematic diagram of a natural purification processing system according to the first embodiment of the present invention.

2, the natural purification system 100 according to the first embodiment includes a collection tank 11, an oxidation precipitation tank 20, an SAPS tank 30, a mixing tank 40, and a marshland 50 Respectively.

The water collecting tanks 11 and 12 temporarily accommodate the mine drainage discharged from the tunnel of the mine. Generally, there are several mines of abandoned mines discharging mine drainage, which can be collected in one sinking tank, or separate sinking tanks for each tunnel. Since the mine drainage discharged from each tunnel may have different pH conditions, the number of the water collecting tanks may be set in a favorable direction in the purification treatment. In the present embodiment, two water collecting tanks are provided, and they are mixed together to be introduced into an oxidizing sedimentation tank 20 to be described later.

The mine wastewater flowing into the two water collecting tanks (11, 12) is mixed and flows into the oxidation precipitating tank (20). The oxidation settling tank 20 is a tank that temporarily receives mine drainage without any particular configuration. The mine wastewater flows into the oxidation settling tank 20 and is discharged after staying for a predetermined time. The heavy metals such as iron and aluminum in the mine drainage are oxidized by oxygen or dissolved oxygen in the atmospheric oxygen precipitation tank 20 to form oxides or hydroxides ≪ / RTI > That is, iron precipitates in the range of pH 3.5 ~ 4.0 and aluminum in the range of pH 6.0 ~ 6.5. Depending on the acidity of the mine drainage, iron and aluminum can be precipitated and removed without any process in the oxide precipitation tank. However, since manganese is generally precipitated at a pH of 9 or higher, some manganese precipitates in the oxidizing sedimentation tank, but most of the manganese remains dissolved in the mine drainage.

The mine drainage discharged from the oxidation settling tank 20 flows into the SAPS tank 30. The SAPS tank (30) is widely used as a conventional mine drainage treatment facility, in which a limestone layer is installed and an organic layer is stacked on the upper layer. Inside the organic material layer, a microorganism carrying purification treatment including a sulfate reducing bacteria and the like is carried. In the SAPS tank 30, the mine drainage flows upward, flows through the organic material layer and the limestone layer in order, and then flows downward to be discharged to the bottom. In the existing SAPS system, if the mine drainage is acidic, the SAPS tank is first placed and the settling tank is placed behind. The acidic mine drainage was passed through the limestone layer of the SAPS tank, and the pH was raised to allow oxidation and precipitation of iron, aluminum, etc. in the sedimentation tank. It is based on the principle that the microorganisms in the organic layer remove the dissolved oxygen in the mine drainage to form an anaerobic environment, so that the heavy metal is not precipitated even when pH is increased in the limestone layer. However, in the actual SAPS tank, oxidation / precipitation of iron and aluminum occurred, which formed sludge on the limestone layer, which caused the flowability of the SAPS tank to deteriorate. Further, iron oxide and iron oxide are coated on limestone, thereby inhibiting the elution of alkali from limestone, thereby deteriorating the neutralization ability of the SAPS tank. However, in the present invention, the oxidizing sedimentation tank 20 is disposed at the front end of the SAPS tank 30, and a considerable amount of heavy metals such as iron and aluminum is precipitated in advance to solve the deterioration of fluidity and neutralization ability, which was a problem in the existing SAPS system. Accordingly, in the present invention, the mine drainage that has passed through the SAPS tank 30 has an advantage that the neutralization treatment can be practically ensured at pH 6 or higher. Of course, in the present invention, iron and aluminum are partially precipitated in the SAPS tank. Although manganese is partially precipitated, manganese still remains in the mine drainage because the pH is not elevated above 9 in the SAPS bath.

In the first embodiment, a mixing reaction tank 40 is disposed at the rear end of the SAPS tank 30. The mixing tank 40 is for oxidizing and precipitating manganese in mine drainage in earnest. The mixing tank 40 is filled with slag and limestone mixed with each other. The mixing ratio of limestone to slag can be determined in the range of 1: 1 to 1: 0.7 in volume ratio, and is mixed in the ratio of 1: 1 in this embodiment. The particle size of the limestone is in the range of 3 to 5 cm, and the particle size of the slag is in the range of 2 to 6 mm. Thus, the slag is mixed in the form of intercalation of limestone. In this embodiment, it is preferable to use cold-rolled steelmaking slag as the slag. As a result of various kinds of slag tests, it was found that the steelmaking slag was most effective in increasing the pH.

The flow directions of mine drainage can be set to two kinds. One of them flows into the side of the mixing reaction tank 40, flows in the horizontal direction and is discharged, and the other flows into the lower part of the mixing reaction tank 40, flows upward, and then is discharged. Experimental results show that manganese removal efficiency is more stable when flowing in a bottom flow than in a horizontal flow.

In the mixed reaction tank 40, the pH of the mine drainage is formed to be 9.0 or more due to the presence of slag, and manganese in the mine drainage is precipitated in the form of oxides (MgO ₂ , Mg (OH) ₂ ). With regard to the precipitation mechanism of manganese in mine drainage, iron and aluminum act as competitive ions. That is, manganese can be oxidized only after the iron and aluminum are first oxidized while the pH is gradually increased. Therefore, manganese can not be oxidized when iron and aluminum in mine drainage coexist with manganese. However, in this embodiment, iron and aluminum having a competitive ion relationship with manganese are mostly oxidized / precipitated in the oxidation precipitation tank 20 and the SAPS tank 30 at the front end and removed from the mine drainage. In the mixing tank 40, A favorable environment that can be oxidized and settled in earnest is created.

On the other hand, in the mixing reaction tank 40, the slag is used to raise the pH of the mine drainage to at least 9 or more, but it should be noted that limestone and slag are mixed. The case of filling only the slag into the reaction tank may be considered. However, since the pH of the mine drainage is more than 9 ~ 10, it does not satisfy the pH condition (pH 8.5 level) suitable for the drainage of the mine drainage. Therefore, a load is required to lower the pH of the marshland disposed at the rear end of the reaction vessel It is not desirable. Experimental results show that manganese treatment efficiency is higher than that of slag - loaded reactor when iron, which is an interfering substance, is mixed with limestone and slag.

By mixing limestone with slag, it is possible to form a mixing tank at a certain volume or more. As a result, the pH is maintained at a level of 8.5 to 9.0 while ensuring the residence time of the mine drainage over a certain period of time. .

The manganese is precipitated in hydroxide form in the mixing tank (40). Another point to note is the autocatalytic activity of precipitated manganese. Here, the self-catalytic action means that when manganese is precipitated in an oxide or hydroxide form, the oxidation and precipitation rate of manganese ions in the mine drainage is increased. More specifically, as the symmetry of the Mn ^{2 +} ions becomes unstable due to the exchange of H ₂ O ligands between manganese ions (Mn ^{2 +} ) and manganese (water) oxides in the mine drainage, the manganese ions are oxidized to oxides or hydroxides . Importantly, the surface of manganese hydroxide is autocatalytic so that oxidation and precipitation of manganese occur easily even if the pH is lower than the pH requirement for the original manganese ion oxidation. Although the autocatalytic action does not occur since the precipitated manganese (water) oxides are not present at the initial stage of the mixing reaction tank 40, after a certain time has elapsed, The operation can be smooth. If the manganese removal action can be ensured in the mixing tank 40, the lower the pH, the more advantageous it is. This is because the pH of the mixing tank should be lowered to 8.5, which is disadvantageous if the pH of the mixing tank is too high. In the present invention, the manganese is precipitated in the form of hydroxide in the mixed reaction tank and is self-catalyzed, so that the pH condition is not necessarily maintained at 9.5 or more.

One thing to note is that manganese precipitates in conventional SAPS tanks, but not in conventional SAPS tanks. The autocatalytic action of manganese is only expressed when manganese precipitates in hydroxide form. In the existing SAPS tank, the pH condition does not exceed 9, so even if manganese precipitates, it does not form a hydroxide but precipitates in carbonate form, that is, MnCO ₃ form.

At the rear end of the mixing reaction tank 40, a wastewater 50 is disposed. The marshland (50) contains organic matter and microorganisms, and the mine drainage is formed at a pH of 8.5, which is the emission standard of the mine drainage, as the pH falls in the marshland. The wastebasket is a well-known structure and a detailed description will be omitted.

As described above, in the natural purification treatment system 100 according to the first embodiment, when mine drainage containing heavy metals such as iron and aluminum together with high concentration manganese is purified, manganese It has the advantage of being able to handle it perfectly. At present, manganese in mine drainage is suggested as 2 mg / L, and in the first embodiment, it can be treated as 1 mg / L or less. The effect of precipitating iron and aluminum, which are competitive ions of manganese, through an oxidizing sedimentation tank, and the action of precipitating manganese with a pH of 8.5 or higher by using slag in a mixed tank, Lt; / RTI > In the above process, the mine drainage can be naturally neutralized and discharged through the marshland.

Hereinafter, a second embodiment of the present invention will be described.

3 is a schematic diagram of a natural purification processing system according to a second embodiment of the present invention.

Referring to FIG. 3, the natural purification processing system 200 according to the second embodiment has the same configuration as that of the first embodiment in the construction of the water collecting tank, oxidizing settling tank, and litter. The operation and effects are also the same, so that a description thereof will be omitted.

The difference from the first embodiment is that the second embodiment includes the modified SAPS tank 230 and the settling tank 240. The modified SAPS tank 230 is formed by integrating the SAPS tank 30 and the mixing tank 40 in the first embodiment. That is, the modified SAPS tank 230 is filled with a mixture of limestone and limestone and slag in the lower part. The organic material layer is laminated on the upper layer. The reason for forming the modified SAPS tank 230 in the second embodiment is to solve the narrowness of the site where the mine drainage natural purification treatment facility can be installed.

The mixing ratio and particle size of limestone and slag in the modified SAPS tank 230 are the same as those in the mixing tank in the first embodiment. In the modified SAPS tank 230, the pH of the mine drainage is slightly lower than that of the mixing tank of the first embodiment, and the manganese removal rate is slightly lower than that of the first embodiment because iron and aluminum are oxidized together with manganese. The oxidized heavy metals including manganese are introduced into the settling tank 240 at the downstream stage and then precipitated and removed from the mine drainage. However, in the second embodiment, there is an advantage that a narrow site problem can be solved. In addition, the problem that the manganese removal rate is low can be achieved by increasing the residence time of the mine drainage to ensure oxidation and precipitation efficiency of manganese to the first embodiment level. If the residence time of the mine drainage is guaranteed to be more than one day in the modified SAPS tank 230, the concentration of manganese in the mine drainage finally discharged through the settling tank 240 and the marshland may be varied depending on the characteristics of the mine drainage. The emission limit can be guaranteed to be less than 2 mg / L. This is because the modified SAPS tank (230) has the same effect as the above-mentioned mixed tank. That is, the pH is higher than that of the existing SAPS solution, so that manganese can be precipitated in the form of hydroxide, and iron and aluminum are mostly precipitated in the oxidizing sedimentation tank. Also, in the modified SAPS tank 230, the manganese hydroxide-type precipitate may autocatalytically oxidize manganese ions even if the pH is not higher than 9.5. It can be said that the removal of manganese from the existing SAPS tank is hardly effected, and it is a remarkable effect compared with the case where a part of the manganese is precipitated in carbonate form.

Hereinafter, experimental procedures and results of the effects of the present invention will be described.

[Experimental Process]

This experiment was carried out by installing the system according to the present invention on a pilot scale in an abandoned coal mine located in Bonghwa, Kyungbuk.

In mine coal mine, two mines were collected and mixed with mine drainage from the 'New 1 Gang' and '1 Gang' respectively. It is predicted that it will be possible to operate the alkali supply tank smoothly by reducing the pollution load of Fe and Al due to the pH increase due to the high pH and the higher pH than the 1 gang 1 gang. And reflected on the pilot device.

The on-site pilot apparatus was constructed and operated in two systems. The first system consists of a catchment tank-oxidizing sedimentation tank -SAPS1-mixed reaction tank-marshland according to the first embodiment of the present invention and the second system comprises a catchment- (Modified SAPS group) - settling tank - litter.

In this case, the mixing reactor of Series 1 is composed of 1: 1 mixture of limestone and steel slag. Horizontal Flow System (HFS) and vertical pipe (Vertical Flow System, VFS). Also, in the SAPS2 of the series 2, unlike the existing SAPS structure, the present invention was mixed with the mine drainage by mixing steel slag 1: 1 with the limestone layer like the modified SAPS of the second embodiment.

The mine water of one gang was located at about 40m below the purification facility, and was transported by using pump from the well. The new one mine water was transferred from the inflow section to the pump in the purification facility oxidation tank so that the two mine water were mixed in the oxidizing sedimentation tank. The flow rate of the new 1 gangs was adjusted to 20 ~ 40% of the total gangue flow including 1 gangs. The design flow of the on - site pilot system is 2 ㎥ / day for each series. For each SAPS, the residence time of 1 day is secured in the lower limestone or mixed medium layer in the waste compost. The settling tank 2 and each series of wetlands were designed to have a residence time of 1.1 days and 9 hours.

In order to evaluate the purification efficiency of the on - site pilot equipment, we monitored the process once or twice a month from 2015 to 2016, excluding the winter season. The Fe ²⁺ and SS concentrations were measured by the phenanthroline method (APHA, 1995) and the photometric method using a portable meter (Orion 3star, Thermo) method (Krawczyk and Gonglewski, 1959) with a DR-890 Colorimeter from HACH.

The sample for dissolved cation analysis was filtered with a 0.45 μm filter paper, collected into a 50 mL sample bottle, and stored under a pH of 2 by adding nitric acid. The sample for anion analysis was filtered with 0.45 μm filter paper, And refrigerated. The cations were analyzed with ICP-OES (Varian 720-ES) and the anions were analyzed with Metrohm Ion Chromatography (Metrohm 850).

[Experiment result]

Two series of pilot systems were installed for the integrated treatment of coal mine gang 1 and gang mine water 1, and water quality change and purification efficiency were monitored from 2015 to 2016. During the monitoring period, the flow rate of the new 1-gangs was about 25 ~ 30% of the total gypsum flow rate. The mixing ratio was close to the flow rate of the two gypsum streams.

The first stage oxidation settling tank for the mixing of mine water improved the low pH of the new gang and reduced the pollution degree drastically so that only the remaining pollutants were present in the majority of Mn. In general, it is known that Al and Fe present in mine drainage reduce the efficiency by coating limestone inside SAPS in oxide form. Therefore, it is predicted that the two series of SAPS reflected in the on-site pilot can maintain the long-term purification efficiency and create an environment in which Mn can be removed intensively in the process after SAPS.

The process efficiency was evaluated by monitoring the first series purification process with a mixed reaction tank for Mn removal. As described above, the mixed reaction tank is divided into HFS and VFS, and the Mn removal efficiency is analyzed by different application by year. In the process of series 1 with HFS, a mixture of 1 new gang and 1 gang of municipal water mixed in a settling tank, resulting in an acidity of about 50 CaCO ₃ mg / L and an Mn of 21 mg / L at an average pH of 5.7, .

As a result of the monitoring, the remaining trace amounts of Fe (2.3 mg / L) and Al (0.7 mg / L) were almost removed and the Mn decreased from 21 mg / L to 12 mg / L Respectively. In addition, in the HFS mixing tank, the pH was increased to 8.5, and the residual manganese in SAPS 1 was reduced to 0.3 mg / L or less and the pH of mine water was almost eliminated. In the latter stage, the marshland buffered the pH to 8, again satisfying the standard values set by the Ministry of Environment.

4 and 5, when the retention time of the limestone layer of SAPS 1 was more than 1 day, it was found that the removal rate of Mn from the SAPS 1 and the HFS type slag, Was more than 50% and more than 80% when it was more than 3 days. In the presence of trace amounts of Fe and Al, Mn removal reaction occurred in SAPS. In the HFS type mixed reaction tank, the Mn removal efficiency was better as the amount of residual Mn in SAPS remained less than 0.5 hour. Even when the residence time is 0.3 hour, 1.73 mg / L of Mn remains, and it is further removed from the marshland to meet the standard value, but it is considered that the residence time of 0.5 hours or more is necessary for the design of the purification plant.

6 and 7, in the purification process of the series 1 with the VFS type mixing tank, an average pH of 6.0, an acidity of 70 CaCO ₃ mg / L and an Mn of 24 mg / L remained in the shear sedimentation tank, . As a result of monitoring by unit process, the acidity and Mn were removed about 13 CaCO ₃ mg / L and 17 mg / L, respectively, while the pH was increased by about 1 in SAPS 1. VFS - type mixed reactors tended to remove residual acidity and Mn in SAPS 1 while raising the pH to 8.76, and the marsh showed a buffering effect by lowering the elevated pH to 7.8. The final effluent satisfies the effluent water tolerance standard as the same method applied to HFS mixed tank.

When the retention time of the SAPS 1 was more than 1 day, it was found that the removal of Mn was more than 50%, and the VFS mixing tank was operated for less than 0.5 hour The residual Mn tended to be almost removed.

In the HFS and VFS steelmaking slag and limestone mixing reactors, the Mn removal performance was excellent in terms of the structural aspect, but it was stable in the residence time with relatively less VFS than HFS. VFS is a structure in which mine drainage flows from the lower end to the upper end through the pipe and reacts with the mixed medium. It is considered that the VFS forms a more homogeneous flow path than HFS and increases the nominal residence time. Also, it is expected that the flow of the VFS forms an upward flow, and the precipitate formed in the reaction tank flows to the upper part of the reaction tank, thereby reducing the deposit coating of the mixing medium and maintaining the long term purification efficiency.

FIG. 8 is a graph showing changes in water quality according to the unit process in the second embodiment (second embodiment), and FIG. 9 is a graph showing manganese removal rates according to the residence time. Referring to the graphs of FIGS. 8 and 9, in Series 2, which contains SAPS 2 having a mixed medium of steel-making slag and limestone as a matrix material, an average pH of 5.8 and an acidity of 68 CaCO ₃ mg / L and 24 mg / Of Mn remained and flowed in. As a result of the analysis of purification efficiency by unit process, the average pH was raised to 8.4 in SAPS 2, and the acidity was reduced to 14 CaCO ₃ mg / L and Mn to 7.5 mg / L. In the sedimentation tank, the pH was lowered while the residual Mn was removed by an average of about 2 mg / L or more, and the final effluent of the marsh had an average pH of 7.6 and Mn of about 3.8 mg / L remained.

As a result of observing the removal of Mn from the substrate material of SAPS 2 according to the retention time, it was found that up to 80% of Mn was removed when the retention time was more than 1 day. In some monitoring intervals, however, Mn More than 70% of them were removed. Unlike the mixed reaction tank of Series 1, the persistence of more than 2 mg / L of Mn in SAPS 2 even when the retention time exceeds 1 day is due to the fact that there is no Fe ²⁺ removal process which inhibits the oxidation precipitation of Mn as in SAPS 1 of Series 1 Because. In general, when Fe ²⁺ and Mn ²⁺ are dissolved at the same time, it is known that Fe ²⁺ is oxidized in succession, and then Mn ²⁺ is oxidized after all of them are removed. Therefore, Fe ^{2 +} Contents seem to have a greater effect on Mn removal than retention time. However, if the residence time is prolonged, the concentration in mine drainage at the end of the summer season will satisfy the standard value.

The removal rates of Fe, Mn, and acidity according to the unit process of series 1 and series 2 were analyzed, and the results are shown in the graphs of FIGS. 10 to 12. 10 to 12, the removal rates of Fe, Mn, and acidity in SAPS 1 were 99%, 69% and 75%, respectively, in the case of Series 1 (FIG. 10) In the reaction tank, the removal rate of Mn was about 29%, and most of the pollutants were removed in the process. The removal efficiencies of Fe, Mn, and acidity of SAPS 1 were 92%, 71%, and 80%, respectively, in Series 1 (FIG. 11) where VFS type mixed reactors were applied. Most of the pollutants were removed. Especially, as the acidity of new gangs increased rapidly during the experiment, Fe was partially remained in SAPS 1 and flowed into the VFS mixing tank, but the Mn removal efficiency remained high.

In the unit process of Series 2 (FIG. 12), the removal rates of Fe, Mn and acidity of SAPS 2 were 96%, 72%, and 79%, respectively, and about 16% of Mn remained even though they passed through the settling tank and the litter. It is considered that the reason why the Mn removal rate is 8.5% in the last process is low due to the low residence time of 0.4 days on average.

Finally, the wastewater at the end of the series 1 and 2 is to remove the remaining metal by adjusting the pH elevated in the reaction tank using the steelmaking slag (Mixer 1 of the series 1, SAPS 2 of the series 2) PH buffering ability was confirmed even at a relatively low residence time. It is known that in aquaculture, high partial pressures of CO ₂ , microbial respiration and organic acid generation in the water and substrate layers regulate the pH of alkaline water. The pH control ability of the marshland was judged as a result of confirming that the land use can be effectively used.

In the figure, SP is an oxidation settler, HFS is a SAPS1 set with horizontal flow, VFS is a SAPS1 set with vertically upward flow, SAPS2 is a modified SAPS set, and W1 and W2 are wetlands.

The scope of protection of the present invention is not limited to the description and the expression of the embodiments explicitly described in the foregoing. It is again to be understood that the present invention is not limited by the modifications or substitutions that are obvious to those skilled in the art.

100, 200 ... Natural purification treatment system
11, 12 ... Sedimentation tank, 20 ... Oxidation settling tank
30 ... SAPS tank, 40 .... mixing tank
50 ... wasteland, 230 .... modified SAPS group
240 ... sedimentation tank

Claims (10)

An oxidizing sedimentation tank that receives mine drainage and oxidizes and deposits metal in mine drainage;
A successive alkalinity producing system (SAPS) which improves the pH of the mine drainage discharged from the oxidation settling tank and oxidizes and deposits the metal in the mine drainage;
The manganese oxide or hydroxide is precipitated by depositing manganese in the mine drainage in the form of oxide or hydroxide by receiving the mine drainage discharged from the SAPS tank, A mixed reaction tank for promoting precipitation of manganese due to self-catalytic action; And
And a marsh that receives the mine drainage discharged from the mixing tank and downs the pH of the mine drainage to meet the discharge standard. The method according to claim 1,
Wherein the mixing tank is made by mixing limestone and slag at a volume ratio of 1: 1 to 1: 0.7. The method according to claim 1,
Wherein the slag is a cold-rolled steelmaking slag. ≪ RTI ID = 0.0 > 18. < / RTI > The method according to claim 1,
Wherein the limestone in the mixing tank has a particle size of 3 to 5 cm and a slag in a range of 2 to 6 mm. The method according to claim 1,
Wherein the mixing tank has an inlet formed at a lower portion thereof and an outlet portion formed at an upper portion thereof so that the mine drainage flows from the lower portion to the upper portion of the mine drainage. As a method for treating mine drainage where manganese is dissolved at a concentration of 20 mg / L or more,
An oxidizing sedimentation tank that receives mine drainage and oxidizes and deposits metal in mine drainage;
In order to improve the pH of the mine drainage discharged from the oxidizing sedimentation tank to 9 or more, limestone and slag are mixed in the lower layer and an organic material layer is stacked in the upper layer, and a modified SAPS tank in which manganese is contained and the heavy metal in the mine drainage is oxidized and settled ;
A sedimentation tank containing manganese drainage discharged from the modified SAPS tank and precipitating heavy metals in mine drainage, including manganese, in the form of oxides or hydroxides; And
And a marsh receiving the mine drainage discharged from the settling tank and lowering the pH of the mine drainage to meet the discharge standard,
Characterized in that the modified SAPS tank mixes limestone and slag in a volume ratio of 1: 1 to 1: 0.7. delete The method according to claim 6,
Wherein the slag is a cold-rolled steelmaking slag. ≪ RTI ID = 0.0 > 18. < / RTI > The method according to claim 6,
Wherein the limestone in the modified SAPS tank has a particle size of 3 to 5 cm and a slag in a range of 2 to 6 mm. The method according to claim 6,
Wherein the modified SAPS set is of a size such that the mine drainage is of a residence size of at least one day.

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