KR20050006091A - A disposal plant of wastewater in mine and a process for treating mine wastewater using the same - Google Patents

Abstract

PURPOSE: To provide an apparatus for disposing mine wastewater, which simplifies the constitution thereof and does not use harmful materials such as FeSO4 as an oxidizing agent, and a method for treating mine wastewater using the same. CONSTITUTION: The apparatus comprises a reactor (21) in which mine wastewater is flown and an aerator is installed under the surface of the mine wastewater, a flocculation tank (22) where the wastewater flown-out from the reactor is flown, a settlement tank (23) where the wastewater flown-out from the flocculation tank is flown, and an effluent tank (24) where the wastewater flown-out from the settlement tank is flown in. The aerator includes a neutralizing agent injection pipe, an upper end of which is protruded over the surface of the mine wastewater to allow neutralizing agent to be injected from the outside.

Description

Mine wastewater treatment apparatus and method for treating mine wastewater using same {A disposal plant of wastewater in mine and a process for treating mine wastewater using the same}

The present invention relates to a mine wastewater treatment apparatus and a mine wastewater treatment method using the same, and more particularly, to a device for treating mine wastewater by a physicochemical method and a mine wastewater treatment method using the same with a simplified configuration.

At present, about 350 abandoned mines nationwide are not operating facilities to prevent outflow from the mines or the prevention facilities are insufficient. Therefore, the environmental pollution problem of mine wastewater flowing out from such abandoned mines is seriously raised. It is becoming.

In addition to the abandoned mines, current coal mines are also being abandoned due to deterioration in profitability and reduced demand for coal.In the mine, the mine wastewater discharges harmful substances such as sulphates into the rivers while eluting heavy metals into the surrounding soil. It is recognized as a major contaminant of water, groundwater, and soil, such as generating sediment.

Mine wastewater is acidic wastewater with pH 2-6 and contains sulfide minerals and heavy metals such as Fe, Al, and Mn. Especially, Fe component suspended or dissolved while occupying about 82% by weight of heavy metals is the main cause of pollution. It is working.

Currently, mine wastewater treatment methods that are applied to the abandoned mines include artificial marsh land method and physicochemical method, and artificial marsh land method is mainly used.

Artificial marsh land method is a method widely used in Europe and the like as a method of precipitating hydroxide according to the pH change of mine wastewater introduced by making artificial pond in a certain place. However, in Korea, there is a problem in that the treatment efficiency does not appear constant because the amount of sunshine, precipitation, temperature, etc. vary greatly depending on the season. In addition, there is a big problem that the sludge precipitated in the artificial marsh land in the rainy season again flows into the river, due to the disadvantage of low site continuity and efficiency of wastewater treatment, the artificial marsh land method is no longer applied.

The physicochemical method is a method of neutralizing mine wastewater and removing heavy metals by adding an alkaline neutralizer, and is currently operated in two places in Korea. 1 is a cross-sectional view showing a mine wastewater treatment apparatus by the physicochemical method currently used.

As shown in FIG. 1, the mine wastewater passes through a pH adjusting tank 1, an aeration tank 2, a neutralization tank 3, a coagulation tank 4, a precipitation tank 5, and a discharge tank 6 in sequence. Purified and discharged.

In the pH adjusting tank 1, ferrous sulfate (FeSO ₄ ) is added as an oxidizing agent, and in the aeration tank 2, excessive aeration is performed to form a precipitate of Fe (OH) _{3 as} a hydroxide while oxidizing Fe ²⁺ ions to Fe ³⁺ ions. Fe can be removed more effectively. In the neutralization tank 3, caustic soda (NaOH) is used as the neutralizing agent.

The mine wastewater treatment apparatus by the physical and chemical method is the most efficient treatment among the mine wastewater treatment method currently operating, but has a very low utilization due to the cost problems and excessive management costs due to the use of chemicals such as oxidants.

The present invention is to solve the problems as described above, the object is to provide a mine wastewater treatment apparatus and a mine wastewater treatment method using the same by reducing the required site, initial investment and maintenance costs by simplifying the configuration of the mine wastewater treatment apparatus To do that.

Another object of the present invention is to provide a mine wastewater treatment apparatus that does not cause environmental pollution by using no toxic substances such as ferrous sulfate (FeSO ₄ ) as an oxidant, and a mine wastewater treatment method using the same.

Still another object of the present invention is to provide a mine wastewater treatment apparatus having a high treatment efficiency at a low cost and a mine wastewater treatment method using the same.

1 is a cross-sectional view showing a mine wastewater treatment apparatus according to the prior art,

2 is a cross-sectional view showing a mine wastewater treatment apparatus according to the present invention,

3 is an enlarged cross-sectional view of the reactor in FIG.

Figure 4 is a graph showing the pH distribution when treated with the mine wastewater raw water, the mine wastewater treatment apparatus of the comparative example and the mine wastewater treatment apparatus according to the present invention,

5 is a graph showing the SS content in the case of treatment with the mine wastewater raw water, the mine wastewater treatment apparatus of the comparative example and the mine wastewater treatment apparatus according to the present invention,

6 is a graph showing the dissolved Fe content in the case of treatment with the mine wastewater raw water, the mine wastewater treatment apparatus of the comparative example and when treated with the mine wastewater treatment apparatus according to the present invention.

In order to achieve the object as described above, the present invention is to perform the functions of the existing pH adjustment tank, aeration tank and neutralization tank in a single reactor, for this purpose it is to install a water stirrer in the reaction tank without using an oxidizing agent and performing an excess aeration It features.

That is, the mine wastewater treatment apparatus according to the present invention, the reaction tank is a mine wastewater is introduced, the reaction tank is installed under the water surface of the mine wastewater; Agglomeration tank into which wastewater from the reactor is introduced; A sedimentation tank into which wastewater from the flocculation tank is introduced; It includes a discharge tank into which the wastewater from the sedimentation tank is introduced, and the underwater stirrer includes a neutralizer inlet tube installed to protrude above the water surface of the mine wastewater so that the neutralizer is introduced from the outside.

The present invention also provides a) injecting the mine wastewater into the reaction vessel is installed a water stirrer under the water surface of the mine wastewater; b) oxidizing soluble or dissolved heavy metals by stirring the mine wastewater using the underwater stirrer; c) adding a neutralizing agent through a neutralizing agent inlet tube installed to protrude above the water surface of the mine wastewater of the agitator and precipitating the soluble or dissolved heavy metal into an insoluble compound; d) flowing the photoacid wastewater containing the insoluble compound into the coagulation tank; e) injecting a polymer flocculant into the flocculation tank and operating a land stirrer to remove suspended matter in the mine wastewater; f) introducing a mine wastewater comprising sediment formed in the flocculation tank into the precipitation tank; g) provides a method for treating mine wastewater comprising the step of introducing the mine wastewater from the sedimentation tank into the discharge tank.

Hereinafter, a mine wastewater treatment apparatus and a mine wastewater treatment method using the same will be described in detail with reference to the accompanying drawings.

Coal mine contains a large amount of sulfide minerals, which are converted into sulfuric acid and iron compounds by oxidation when exposed to oxygen, and the generated acid is dissolved in water to lower the pH of the surrounding natural water.

Therefore, mine wastewater is acidic wastewater with a pH of 2-6, and a substance which comes into contact with acidic water elutes heavy metal elements from lipids. Acid mine wastewater contains various harmful ions, such as iron, manganese, zinc, cadmium, and lead, depending on the contacting lipids.

In the present invention, the environmental engineering principle is used so that the pollutants in the mine wastewater artificially create the environment in which the pollutants are most difficult to exist, so that the pollutants are removed from the water body. In the physicochemical process, the process unit is determined by the wastewater characteristics and the treatment target. Therefore, it is important to design the most efficient treatment process taking into account the chemical properties of the problematic ones, such as iron, manganese and aluminum, among the mine wastewater.

2 is a cross-sectional view showing a mine wastewater treatment apparatus according to the present invention, Figure 3 is an enlarged cross-sectional view of the reaction tank in FIG.

As shown in these figures, the mine wastewater treatment apparatus according to the present invention comprises a reaction tank 21, a flocculation tank 22, a settling tank 23, and a discharge tank 24, so that the mine wastewater treatment tank 21 After passing through the flocculation tank 22, the settling tank 23, and the discharge tank 24 sequentially, it is purified and discharged.

Compared with the conventional mine wastewater treatment system applying the conventional physicochemical method, the pH adjustment tank, aeration tank, and neutralization tank is characterized in that the present invention is replaced by a single reactor (21). In other words, in the present invention, pH adjustment, oxidation, and neutralization are performed in one reactor. As such, the existing three tanks are replaced by one tank in the present invention, and the site area required is reduced by about 40-50%, and the hydraulic retention time of the mine wastewater for the treatment device is short, so that a large amount of mines can be shorter. Wastewater treatment is possible.

An underwater stirrer 30 is installed inside the reactor 21, and the underwater stirrer 30 includes an impeller 32 that rotates about a rotation shaft 31, a motor 33 that provides power of the rotational movement, and , Wastewater inlet (34) into which the mine wastewater is introduced, a neutralizer inlet tube (35) installed so that the upper end protrudes above the water surface of the mine wastewater so that the neutralizer is introduced from the outside, and the wastewater introduced from the wastewater inlet by the rotary motion of the impeller (reaction tank) 21) consists of wastewater outlets 36 installed on both sides to flow out of the water stirrer 30 inside.

The underwater stirrer 30 is installed below the water surface of the mine wastewater 10 in the reaction tank 21 to stir the wastewater in the reaction tank 21 while flowing in and out of the wastewater by the rotary motion of the impeller 32. Underwater stirrer can be adjusted to 1000 to 1800 rpm, preferably 1500 to 1800 rpm to optimize the reaction time in the reactor.

If the throughput of the mine wastewater is large, the preliminary reaction tank in which the land stirrer is installed may be additionally installed before the reactor 21 in which the underwater stirrer 30 is installed. The land stirrer has a motor on the surface of the water, and the stirring speed is smaller than that of the water stirrer, but a large amount of sewage treatment is possible, so that the wastewater can be treated more efficiently.

The neutralizing agent nozzle is connected to the upper end of the neutralizing agent inlet pipe 35 of the underwater stirrer to inject the neutralizing agent into the wastewater, and the diameter of the neutralizing agent inlet pipe 35 is greater than or equal to that of the neutralizing nozzle. If the diameter of the neutralizer inlet pipe 35 is larger than the neutralizer nozzle, air in the atmosphere is sucked together through the neutralizer inlet pipe 35 outside the nozzle by the rotational movement of the impeller.

Therefore, the air introduced together with the neutralizing agent serves to oxidize the heavy metal. For example, in the case of iron, which is the most present in mine wastewater, soluble Fe ²⁺ ions are oxidized to Fe ³⁺ ions, thereby forming a precipitate of the hydroxide Fe (OH) ₃ to remove dissolved Fe more effectively. . In the present invention, there is no need to use a toxic oxidant such as FeSO ₄ used in the conventional physicochemical method of mine wastewater, resulting in a cost reduction effect and can prevent secondary environmental pollution due to chemical oxidant.

If the diameter of the neutralizer inlet pipe 35 is the same as that of the neutralizer nozzle, there is no inflow of air into the atmosphere, but the treatment efficiency of the mine wastewater does not change significantly. This is because 7-9 mg / l dissolved oxygen is present in the waste water when the stirring speed of the stirrer is increased to serve as an oxidizer. For example, when oxidizing Fe ²⁺ to Fe ³⁺ , 1 ppm of dissolved oxygen is required per 7-9 ppm of iron ions. Whether air in the atmosphere can be easily determined by the concentration of metal in the mine wastewater.

Existing aeration wastewater treatment apparatus of the conventional physicochemical method used an excess aeration tank to oxidize heavy metals, but in the present invention, excess oxygen is used due to the use of dissolved oxygen generated by agitation of air or agitator through the neutralizer inlet pipe of the agitator. No aeration tank is required. Therefore, it is possible to reduce the power cost due to the use of excess aeration tank.

In the mine wastewater treatment apparatus of the present invention, an excess aeration tank is not required, but a separate aeration apparatus may be installed in the reaction tank as necessary to facilitate the efficient treatment of the mine wastewater.

By the addition of the neutralizing agent, the pH in the reaction tank can be adjusted to a range capable of efficiently treating the metal in the mine wastewater. For example, iron in the mine wastewater contains Fe ²⁺ or Fe ³⁺ , of which Fe ²⁺ forms hydroxides at pH 8-10, while Fe ³⁺ easily forms hydroxides at pH 7-8. Do. Chemical properties of such ferrous metals can be used to maximize the efficiency of heavy metal removal in the mine wastewater.

That is, the neutralizer directly introduced into the agitator 30 through the neutralizer inlet tube 35 maintains the pH of the initial wastewater in an appropriate range of about 9-10, thereby causing precipitation with ferric hydroxide, and then the pH of the wastewater in the reactor. Is maintained at about 7-8, thereby causing precipitation with trivalent hydroxide to create conditions under which soluble or dissolved heavy metals (Fe, Al, Mn, As) in the waste water can precipitate.

Caustic soda may be used as the neutralizing agent, or liquid lime (Ca (OH) ₂ ) may be used instead of caustic soda. Liquid lime in slaked lime has the advantage that the cost is low and the overall cost of mine wastewater treatment can be reduced. In addition, liquid lime is not toxic compared to caustic soda (NaOH) can prevent secondary environmental pollution due to the use of toxic chemicals. The liquid lime is preferably used after purification.

Liquid slaked lime has been used in air desulfurization facilities but has never been used in water purification. Liquid slaked lime also acts as an auxiliary coagulant. When liquid slaked lime is used, it is necessary to use a soil modifier separately. There is no advantage. The purified liquid slaked in the liquid slaked lime is preferable because it has a fast neutralization reaction and a small amount of sludge.

Since the residence time in the reactor 21 depends on the properties of the mine wastewater, the stirring speed and the like can be adjusted to allow sufficient oxidation and neutralization reactions to proceed.

The acid wastewater from which the oxidation and neutralization reactions are completed in the reactor 21 is introduced into the coagulation tank 22. In the coagulation tank 22, the colloidal metal complex compound is formed into a large and heavy floc by using a polymer flocculant and a land stirrer to improve the settling property. In addition, suspended solids (SS) in the coal mine wastewater are removed from the flocculation tank 22.

Anionic polymer coagulant may be preferably used as the polymer coagulant. Examples of the anionic polymer flocculant include carboxylate compounds, higher alcohols, higher alkyl ethers, sulfate ester compounds containing sulfates of olefins, sulfate compounds including alkylbenzensulfonate, and higher alcohols. Phosphorylated phosphate compounds are typical. Specific examples include sodium lauryl sulfate ('SLS'), sodium lauryl ether sulfate (SLES), linear alkylbenzenesulfonate (LAS), monoalkyl phosphate (MAP), acyl isethionate (acyl) isethionate, SCI), and alkyl glyceryl ether sulfonate (AGES), acyl glutamate, acyl taurate, fatty acid metal salts, among which are preferably widely used. It is better to use SLS, SLES, LAS, or SCI.

The mine wastewater passing through the coagulation tank 22 is introduced into the precipitation tank 23. In the sedimentation tank 23, the floc is naturally precipitated by gravity to separate the liquid and the supernatant is introduced into the discharge tank 24 for final discharge, and the sludge generated in the sedimentation tank 23 is introduced into the reaction tank of the existing treatment process facility. The cake dehydrated in the treatment process is recycled as a feedstock for the cement plant.

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only one preferred embodiment of the present invention and the present invention is not limited to the following examples.

1. Mine wastewater

Gangwon-do offshore water was collected on January 4, 2003, 2/7 and 3/3 in 2003 and used as raw water. The pH of the treated raw water was about 6.2 (FIG. 4), the suspended solids (SS; suspension solid) level was 80 to 130 ppm (FIG. 5), and the content of dissolved Fe was 3 to 17 ppm (FIG. 6).

2. Comparative Example 1: Existing Mine Wastewater Treatment System

The mine wastewater (wastewater treatment amount) is treated in a treatment device including a pH adjusting tank 1, an aeration tank 2, a neutralization tank 3, a flocculation tank 4, a precipitation tank 5, and a discharge tank 6 shown in FIG. This 18,720 m ³ / day design) was purified while staying sequentially. In the pH adjusting tank (1), 250 kg / day of ferrous sulfate (FeSO ₄ ) is added as an oxidizing agent, and in the aeration tank (2), an excessive amount of rotary blower (Rotary Blower: 440V * 55Kw * 45㎥ / min * 4000mm Aq) is used. Aerated, caustic soda 750kg / day was added to the neutralization tank (3), and anionic polymer coagulant (trade name: A211P, manufacturer: Cheongmyung Chemical Co., Ltd., viscosity: 170-230 cps, pH 6-8) was added to the coagulation tank. 27 kg / day was added.

The residence time of the treatment apparatus was 23.04 minutes in the pH adjustment tank, 105.30 minutes in the aeration tank, 23.04 minutes in the neutralization tank, 23.04 minutes in the flocculation tank, and 203.4 minutes in the precipitation tank.

When treated using the mine wastewater treatment apparatus of Figure 1 pH was 8-9 (Fig. 4), SS content is 15ppm or less (Fig. 5), dissolved Fe content was found to be 5ppm or less (Fig. 6).

3. Example 1: The mine wastewater treatment apparatus of the present invention

In the mine wastewater treatment apparatus (wastewater treatment designed to 18,720m ³ / day) of the reaction tank 21, the flocculation tank 22, the settling tank 23, and the discharge tank 24 shown in FIG. The mine wastewater was purified while staying in sequence. In the reactor was installed a water stirrer shown in FIG. 5600 L / day of liquid calcined lime was added to the reactor as a neutralizing agent, and 27 kg / day of anionic polymer flocculant (trade name: A211P, manufacturer: Cheong Myung Chemical Co., Ltd., viscosity: 170-230 cps, pH 6-8) was added to the reaction tank.

The residence time of the treatment apparatus was 50 minutes in the reaction tank, 50 minutes in the flocculation tank and 230 minutes in the precipitation tank.

When treated using the mine wastewater treatment apparatus of FIG. 2, the pH was about 8 (FIG. 4), the SS content was 15 ppm or less (FIG. 5), and the dissolved Fe content was maintained to be 5 ppm or less (FIG. 6).

Table 1 shows the power consumption of the mine wastewater treatment apparatus of Comparative Example 1 and Example 1.

Comparative Example 1 Example 1 pH adjustment tank 440 V, 11 kW 440 V, 5 kW (reactor) Aeration tank 440 V, 55 kW China 440 V, 11 kW Agglomeration tank 440 V, 11 kW 440 V, 11 kW Sedimentation tank 440 V, 22 kW 440 V, 22 kW

As described in Table 1, in the case of the mine wastewater treatment apparatus according to the present invention, by replacing the pH reactor, the aeration tank, the neutralization tank with one reactor and not installing the aeration tank, it is 1/15 compared with the mine wastewater treatment apparatus of Comparative Example 1. It can be seen that the abnormal power consumption can be reduced.

In addition, the annual costs consumed for the injected drugs are shown in Table 2 below. Table 2 shows the drug costs in Comparative Example 1, which is a conventional mine wastewater treatment apparatus, and compares the drug costs in Example 1 and Comparative Example 1.

medicine Example 1 Comparative Example 1 Ferrous sulfate - 270kg / day X150 month / kg = 40,500 won / day ≒ 1,215,000 won / month ≒ 14,580,000 won / year Caustic soda - 750kg / day * 550 won / kg = 412,500 won / day 12,375,000 won / month 148,500,000 won / year Liquid lime 5600ℓ / day * 40 won / ℓ = 224,000 won / day ≒ 6,720,000 won / month ≒ 80,640,000 won / year - Total (annual cost) KRW 80,640,000 / year 164,080,000 KRW / year

As shown in Table 2, it was found that the drug cost was reduced by about 51% compared to each other except the polymer coagulant, which is commonly added in a similar amount.

4. Example 2: The mine wastewater treatment apparatus of the present invention

In Example 2, it was purified in the same manner as in Example 1 using the external water in the Samma area, Gangwon-do. The mine wastewater in the Suma region is a mine wastewater with a relatively low pH with a pH of 2-3. The result of measuring the content of various metal elements after purification was shown in Table 3, and the content of metal elements of raw water was also shown for comparison.

Unit: ppm enemy After purification Al 43.30 1.02 Mn 18.51 0.56 Fe 208.44 6.88

As shown in Table 3, it can be seen that the content of the metal element is significantly reduced compared to the raw water. Thus, the mine wastewater treatment apparatus of the present invention can efficiently treat the mine wastewater having a low pH.

As described above, in the present invention, the existing pH adjusting tank, aeration tank, and neutralization tank are replaced with a single reaction tank, thus reducing initial investment costs and simple mechanical facilities, thus reducing management costs and using no toxic substances. There is a saving effect.

In addition, the existing pH adjustment tank, aeration tank, and the neutralization tank is integrated into a single reaction tank to shorten the residence time of the waste water has the effect of significantly shortening the waste water treatment process time.

In the present invention, it is possible to apply to all mine wastewater in the range of pH 2 ~ 6, which is a characteristic of mine wastewater, and does not use a toxic oxidant, and does not use a separate aeration device. It is effective in preventing secondary pollution and reducing power costs due to aeration.

Claims (13)

A reaction tank into which the mine wastewater is introduced and an underwater stirrer is installed below the water surface of the mine wastewater; Agglomeration tank into which wastewater from the reactor is introduced; A sedimentation tank into which wastewater from the flocculation tank is introduced; Discharge tank into which wastewater from the sedimentation tank flows Including; The underwater stirrer is a mine wastewater treatment apparatus comprising a neutralizer inlet tube is installed so that the upper end protrudes above the water surface of the mine wastewater so that the neutralizer is introduced from the outside. The method of claim 1, The underwater stirrer includes an impeller rotating around a rotating shaft, a motor providing power of the rotating motion, a wastewater inlet opening upwardly so that the mine wastewater flows in, and the wastewater inlet by a rotational movement of the impeller. The mine wastewater treatment apparatus further comprises a wastewater outlet installed so that the mine wastewater introduced from the wastewater flows out of the agitator. The method of claim 1, The diameter of the neutralizer inlet pipe is greater than or equal to the nozzle diameter of the neutralizer wastewater treatment apparatus. The method of claim 1, The neutralizing agent is caustic soda (NaOH) or liquid lime (Ca (OH) ₂ ) mine wastewater treatment apparatus. The method of claim 1, The treatment apparatus further comprises a preliminary reaction tank including a land stirrer in front of the reaction tank. The method of claim 1, The reactor is a mine wastewater treatment apparatus further comprising an aeration device. a) injecting the mine wastewater into a reactor equipped with an agitator below the water surface of the mine wastewater; b) oxidizing soluble or dissolved heavy metals by stirring the mine wastewater using the underwater stirrer; c) precipitating the soluble or dissolved heavy metal into an insoluble compound by introducing a neutralizing agent through a neutralizing agent inlet tube installed to protrude above the surface of the mine wastewater of the agitator; d) flowing the photoacid wastewater containing the insoluble compound into the coagulation tank; e) injecting a polymer flocculant into the flocculation tank and operating a land stirrer to remove suspended matter in the mine wastewater; f) introducing a mine wastewater comprising sediment formed in the flocculation tank into the precipitation tank; g) A method of treating mine wastewater, comprising the step of introducing the mine wastewater from the settling tank into the discharge tank. The method of claim 7, wherein The underwater stirrer includes an impeller rotating around a rotating shaft, a motor providing power for the rotating motion, a wastewater inlet opening upwardly to allow the mine wastewater to flow, and the wastewater inlet by the rotary motion of the impeller. And a wastewater outlet configured to flow out of the mine wastewater introduced from the reactor to the outside of the agitator. The method of claim 7, wherein The diameter of the neutralizing agent inlet pipe is greater than or equal to the nozzle diameter of the neutralizer wastewater treatment method. The method of claim 7, wherein The neutralizing agent is caustic soda (NaOH) or liquid lime (Ca (OH) ₂ ) method of treating mine wastewater. The method of claim 7, wherein The treatment apparatus further comprises a preliminary reaction tank including a land stirrer in front of the reaction tank. The method of claim 7, wherein The reactor is a mine wastewater treatment method further comprising an aeration device. The method of claim 7, wherein Further comprising the step of supplying oxygen in the atmosphere through the neutralizer inlet pipe.