TW201602015A - Mine water purification method, mine water purification system and mine water purifying agent - Google Patents

Abstract

Provided is a mine water purification method capable of removing ferrous iron contained in mine water more efficiently and at lower cost. The mine water purification method of the present invention is characterized by comprising a first step of collecting, and loading into a container, iron oxide hydroxide sediments that have settled in a mine water channel between a mine head and a mine water treatment plant, and a second step of removing ferrous iron from the mine water by feeding the mine water into the container and allowing it to stand, so that the action of iron-oxidizing bacteria naturally present in the iron oxide hydroxide sediments oxidizes the ferrous iron in the mine water and causes deposition of iron compounds.

Description

Purification method of mine pit water, purification system of mine pit water and purifying agent of mine pit wastewater

The invention relates to a method for purifying pit water for removing divalent iron ions from mine waste water, a purification system for mine pit water and a purifying agent for mine pit water.

In the mine pit of metal mines, various metal ions such as Fe, Zn, Cu, Pb, Cd, and As are usually contained, and there are a large number of metal ions that may have harmful effects on the human body or the environment. Therefore, when discharging the mine waste water, it is necessary to carry out treatment to meet the drainage standards established by each country. Recently, there is a tendency for countries or regions to make the drainage standard more stringent than the current situation to prevent environmental pollution, and it is strongly expected to develop a technology that inexpensively reduces the concentration of metal ions contained in the pit water.

In the case where the pit wastewater contains the metal ions, it also contains a sulfate ion (SO ₄ ^2- ) of about 50 mg/L to 3000 mg/L. Therefore, in recent years, a technique of removing metal ions from mine pit wastewater by utilizing the action of sulfuric acid reducing bacteria has been studied. In this technique, sulfate ions are reduced by reducing sulfuric acid ions in the pit wastewater by sulfuric acid reducing bacteria, and the sulfide ions are reacted with metal ions to precipitate metal sulfides, thereby removing metal ions from the pit water.

However, it is difficult to efficiently remove iron ions from the pit wastewater by a purification method using the action of the sulfate reducing bacteria. The reason for this is that iron sulfide has a high solubility with respect to water even in the neutral domain, and is not easily precipitated as a sulfide. Therefore, the inventors of the present invention have embarked on a method of efficiently removing iron ions at a stage before purifying the pit wastewater by a purification method using the action of the sulfate reducing bacteria.

As a method of removing iron ions from mine pit water, a method of utilizing the action of iron oxidizing bacteria is known. Patent Document 1 describes a method for purifying a pit water having a ferrite oxidation and deferring step by adhering to a surface of a silicate-based fibrous inorganic substance and multiplying The action of the iron oxidizing bacteria oxidizes the divalent iron ions in the pit wastewater to ferric ions and simultaneously precipitates them as iron oxide compounds. In this document, examples of the phthalate-based fibrous inorganic material include a mixture of a phthalate-based inorganic fiber such as rock wool and a silicate-based inorganic granule such as cement or iron ore slag.

Patent Document 2 describes a method for oxidizing iron, which comprises adding iron oxidizing bacteria to water containing ferrous iron, performing aeration, and then agitating while aerating, thereby oxidizing ferrous iron to trivalent. iron. In this document, a coagulant is added to precipitate iron hydroxide produced by water treatment by this method in an oxidizing thickener. Since the iron oxidizing bacteria survive in the precipitated iron oxide precipitated mud, the iron oxide precipitated mud is used as a source of addition of the iron oxide bacteria. Prior art literature

Patent Document 1: Japanese Patent Laid-Open Publication No. Hei. No. 2005-58955. Patent Document 2: Japanese Patent Laid-Open Publication No. 2013-107027

[Problems to be solved by the invention]

However, the phthalate-based fibrous inorganic substance used in Patent Document 1 requires the start-up cost of the material or the manufacturing time. In order to be used in a pit wastewater treatment plant that exists in a mountainous area, transportation costs are usually required, so in terms of cost. unfavorable. In addition, the silicate-based fibrous inorganic substance functions only as an iron-oxidizing bacterium which only supports the iron oxidizing bacteria originally present in the pit waste water, or is added to the septic waste water, and does not originally have iron. Oxidizing bacteria, there is still room for improvement regarding the removal efficiency of iron ions.

Further, Patent Document 2 is a method of returning iron-oxidized precipitated sludge after water treatment to a water treatment tank. The iron oxide precipitated sludge is obtained by precipitating iron hydroxide formed by a coagulant. As described above, in terms of an additional chemical such as a coagulant or a sedimentation tank for precipitating sediment crystals, there is a problem that the system as a whole is complicated and costly.

Accordingly, the present invention has been made in view of the above problems, and an object thereof is to provide a method for purifying a pit water which can remove ferrous ions contained in a pit water more efficiently and at low cost, a pit purification system, and a pit wastewater. purifier. [Means for solving the problem]

In order to achieve the object, the present inventors focused on the precipitate of iron hydroxide hydroxide precipitated in the pit drainage water conduit from the pit of the mine to the pit wastewater treatment plant. In the precipitate, the iron ions in the pit water gradually become iron oxidized hydroxide and are gradually deposited in the pit water drainage channel without adding an additional agent such as a coagulant, and are periodically removed and treated as waste. However, the inventors of the present invention considered that iron oxidizing bacteria present in the pit water flowing through the water conduit are concentrated and accumulated in the precipitate at a high concentration. Therefore, the precipitate is collected, filled into a container, and the pit water is introduced into the container and allowed to stand. From this, it was found that the total iron concentration including the divalent iron ions in the pit wastewater was reduced in a short time, thereby completing the present invention.

The gist of the present invention completed based on the above findings is as follows. (1) A method for purifying a pit water, comprising: a first step of collecting iron hydroxide hydroxide precipitate deposited in a pit drainage conduit from a pit of a mine to a pit wastewater treatment plant, and filling the container with a container And a second step of introducing the pit water into the container and retaining it, thereby using the action of the iron oxidizing bacteria originally contained in the iron hydroxide hydroxide precipitate to treat the second of the pit wastewater The ferrous ions are oxidized to precipitate an iron compound, thereby removing the ferrous ions from the pit wastewater.

(2) The method for purifying a pit water according to the above (1), wherein the second step is a continuous water passing step of continuously introducing the pit wastewater into the container, and the remaining time is retained The pit water is continuously discharged from the container.

(3) The method for purifying a pit water according to the above (2), further comprising a third step of introducing the pit wastewater discharged in the second step to a carrier filled with a sulfate-retaining bacteria-preserving carrier In the second container, the second container is maintained in an oxygen-deficient state, and the pit waste water is retained, whereby the heavy metal other than the divalent iron ions in the pit wastewater is utilized by the action of the sulfuric acid reducing bacteria. Ion sulfides are precipitated to remove the heavy metal ions from the pit wastewater.

(4) The method for purifying a pit water according to the above (3), wherein the third step is a continuous water passing step, continuously introducing the pit wastewater into the second container, and staying for a specific time The pit wastewater is continuously discharged from the second container.

(5) The method for purifying a pit water according to any one of (1) to (4), wherein the pit water is a pit water flowing through a water conduit of the pit water.

(6) A mine pit purification system characterized by: a container filled with precipitated iron hydroxide hydroxide precipitated in a pit drainage conduit from a pit of a mine to a pit wastewater treatment plant; a supply system, Continuously introducing the pit water into the container; and discharging the system to retain the ferrous iron in the container for a specific period of time and by the action of iron oxidizing bacteria originally contained in the iron hydroxide hydroxide precipitate The pit water from which the ions are removed continues to be discharged from the container.

(7) The mine waste water purification system according to (6), further comprising: a second container filled with a carrier retaining sulfuric acid reducing bacteria and maintaining an anoxic state; a second supply system, from said The pit waste water discharged from the discharge system is continuously introduced into the second container; and the second discharge system is retained in the second container for a specific time and by the action of the sulfuric acid reducing bacteria The pit water from which heavy metal ions other than the valence iron ions are removed continues to be discharged from the second container.

(8) A purifying agent for mine pit water, which is a purifying agent for removing pit water of the divalent iron ion from pit water containing divalent iron ions, characterized in that it contains iron oxidizing bacteria and contains collection The precipitation of iron hydroxide hydroxide in the pit drainage conduit from the pit of the mine to the pit wastewater treatment plant. [Effects of the Invention]

The method for purifying the pit water according to the present invention, the purification system of the pit water and the purifying agent for the pit water can remove the divalent iron ions contained in the pit wastewater more efficiently and at low cost.

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

The pit wastewater to be subjected to the embodiment of the present invention is not particularly limited as long as it contains at least divalent iron ions. For example, mine pit wastewater in metal mines in Japan usually contains metal ions containing heavy metals such as Fe, Zn, Cu, Pb, Cd, and As, and further contains sulfate ions (SO ₄ ² ) of about 50 mg/L to 3000 mg/L. ^- ). The pH of the pit wastewater is usually about 3.0 to 8.0.

(Method for Purifying Pit Waste Water) A method for purifying pit water according to an embodiment of the present invention is to remove divalent iron ions from mine pit water by the action of iron oxidizing bacteria.

The present embodiment is characterized in that a precipitate of iron hydroxide oxide (hereinafter also simply referred to as "precipitate") precipitated in a pit water discharge conduit from a pit of a mine to a pit wastewater treatment plant is collected and used as a purifying agent. The precipitate is a mineral waste water conduit that is gradually added to the pit from the pit of the mine to the pit wastewater treatment plant without adding an additional agent such as a coagulant, and the iron ions in the pit water gradually become iron oxide hydroxide, and are periodically removed. . Since the precipitate has heretofore been treated as waste, the cost of starting is very low or not at all, and the cost of waste disposal can also be reduced.

The main component (50% by mass or more) of the precipitate is iron oxide oxyhydroxide FeO(OH), and also contains a small amount of iron oxide Fe ₂ O ₃ . When elemental analysis is performed on the dried precipitate, Fe is 40% by mass to 75% by mass, and Zn, Cu, Al, Mn, Cd, Ca, Mg, and Si are all impurity levels of less than 1% by mass. It is presumed that the unidentified residue is a hydroxide ion of iron hydroxide oxide or a biofilm derived from microorganisms (organic hydrocarbon). The iron oxidizing bacteria are concentrated at a high concentration and accumulated in the precipitate.

In the present embodiment, in the state in which the precipitate is collected and collected, it is not required to be dried, and is supplied as a purifying agent to the purification treatment of the pit water. That is, the precipitate can be used as it is without any processing.

That is, the method for purifying the pit wastewater of the present embodiment includes the first step of collecting the precipitate and filling it into a container.

Further, the method for purifying the pit water of the present embodiment includes a second step of introducing the pit water into the container and allowing it to stay. In the second step, the iron compound is oxidized by the action of the iron oxidizing bacteria originally contained in the precipitate to precipitate the iron compound, thereby removing the ferrous ions from the pit wastewater. In addition, iron oxidizing bacteria are usually contained in the pit wastewater to be treated. Therefore, the iron oxidizing bacteria contained in the pit wastewater to be treated also contribute to the oxidation of the divalent iron ions.

Iron oxidizing bacteria promote the following reactions. Fe ²⁺ +H ⁺ +1/4O ₂ →Fe ³⁺ +1/2H ₂ O

The ferric ion becomes an iron compound (mainly FeO(OH)) in an environment having a pH of 3 to 4, which precipitates and precipitates. The precipitated iron compound remains in the scavenger. Thereby, the divalent iron ions are removed from the pit water. In the present embodiment, not only the iron oxidizing bacteria originally contained in the precipitate contributes to the removal of the ferrous iron, but also the iron oxidizing bacteria in the pit wastewater to be treated contributes to the removal of the ferrous iron. Therefore, the ferrous ions contained in the pit wastewater can be removed more efficiently. In addition, the total iron concentration including divalent iron ions, ferric ions, and all other iron compounds is reduced from the pit wastewater.

The type of the iron oxidizing bacteria is not particularly limited, and examples thereof include Acidithiobacillus ferrooxidans, Leptothrix ochracea, Gallionella ferruginea, and Proteus ferrooxidans (Ferrovum myxofaciens). )Wait. In the actual test, Ferrovum myxofaciens was detected.

The container in the present embodiment is not particularly limited as long as it is filled with a precipitate. The vessel may be a column having a specific volume, or a portion of an existing pit drainage conduit may be used. In the latter case, there is also a case where it is not necessary to add a processing device.

The residence time of the pit water in the vessel and the amount of the precipitate to be filled with respect to the amount of the pit water can be appropriately set according to the concentration of the divalent iron ions contained in the pit water, the concentration of the target divalent iron ion, and the like.

The temperature inside the container is preferably set to 0 ° C or higher and lower than 50 ° C. If it is 50 ° C or more, the iron oxidizing bacteria are killed, so the oxidation reaction of the ferrous iron is not performed.

The second step can be set as a continuous water passing step, that is, continuous introduction of the pit water into the container, and the discharge of the pit water retained for a specific time is continuously discharged from the container. Thereby, the divalent iron ions can be continuously removed from the pit water. Furthermore, the pit water may remain in the container for a certain period of time. For example, the container may be filled with the state of the pit water (that is, the state in which the sediment is immersed in the pit water), or the pit water may not be filled in the container. And naturally flow from top to bottom through a container containing sediment.

After the removal of the divalent iron ions by the second step, a third step of removing heavy metal ions other than the divalent iron ions by the action of the sulfuric acid reducing bacteria can also be performed. Sulfate-reduction bacterium (SRB) is a heterotrophic bacterium that uses organic matter as a respiratory substrate in the presence of sulfate ions, and has a role of reducing sulfate ions as shown in the following reaction formula (1). . That is, the sulfuric acid reducing bacteria absorb the organic matter and the sulfate ions, and release the hydrogen sulfide ions. 2CH ₂ O+SO ₄ ^2- =2HCO ₃ ^- +HS ^- +H ⁺ (1) wherein CH ₂ O is an organic substance.

The sulfate-reducing bacteria are mainly anaerobic bacteria, which are active in the neutral domain (pH 5 to 8), and are active as a respiratory substrate, and are bacteria which reduce sulfuric acid, and are not particularly limited, and for example, Desulfovibrio vulgaris and the like. Further, in actual tests, Desulfovibrio magneticus, Desulfarrculus baariss, Desulfotomaculum acetoxidans, Desulfobulbus propionicus, and the like were detected.

When the reduction reaction of the reaction formula (1) (the reaction in the right direction of the reaction formula (1)) is carried out, hydrogen sulfide ions (HS ^- ) are generated, and the generated hydrogen sulfide ions (HS ^- ) and the water to be treated are The metal ions are combined to form a sulfide of the metal ion as in the reaction formula (2) shown below. Me ²⁺ +HS ^- = MeS↓+H ⁺ (2) where Me is a metal.

In the third step, the pit wastewater discharged in the second step is introduced into the second container filled with the carrier holding the sulfuric acid reducing bacteria, and the pit water is retained while maintaining the second container in an oxygen-deficient state. Thereby, the sulfide of the heavy metal ions other than the divalent iron ions in the pit wastewater is precipitated by the action of the sulfuric acid reducing bacteria, whereby the heavy metal ions can be removed from the pit water.

As a carrier which retains a sulfuric acid reducing bacteria, a cereal shell is mentioned, for example. The cereal shell has a shape suitable for supporting a bacterial population associated with sulfate ion reduction activity containing a sulfate-reducing bacterium. Therefore, not only a part of the cereal shell is decomposed into an organic substance (low molecular organic substance) which is a respiratory matrix of the sulfuric acid reducing bacteria, but also has a function of supporting a bacterial group related to sulfate ion reducing activity containing a sulfuric acid reducing bacteria. Examples of the cereal shell include rice husks and buckwheat hulls. A bacterial population associated with sulfate-reducing activity containing sulfate-reducing bacteria is usually attached to the cereal shell collected from nature. The grain crust is originally a waste of biomass resources, and it is easy to start with a large amount of money. In addition, the shape is also granular, and it is not necessary to cut or crush, and the processing is simple, and the material unevenness is relatively small.

Further, among the bacterial groups related to the sulfate ion reducing activity, bacteria other than the sulfuric acid reducing bacteria are anaerobic bacteria which decompose a part of the cereal shell and supply a low molecular organic substance which can be used as a respiratory matrix of the sulfuric acid reducing bacteria. Most anaerobic bacteria digest organic matter and excrete acetic acid. Since acetic acid is one type of organic acid which can be utilized by a sulfuric acid reducing bacteria, it is possible to supply an organic substance which can be absorbed by a sulfuric acid reducing bacteria, in particular, without specifying a species of an anaerobic bacterial group. Therefore, the type is not limited, and examples thereof include acetic acid bacteria, lactic acid bacteria, deaza bacteria, Escherichia coli, Bacillus subtilis, hydrogen-producing bacteria, and yeasts as fungi. In addition, in actual experiments, Azospira sp., Clostridium sp, Dechloromonas sp, Hydrogenophaga sp, and denitrifying bacteria were detected. Simplicispira sp), Hydrogenophaga sp, Nitrospira sp, Spirochaeta sp, and the like. These bacteria are attached to the grain shell and other bacterial sources.

In addition to the cereal shell, the second container may contain an organic material containing 5% by mass or more of crude protein. The crude protein contained in the organic material is decomposed by various bacteria into an organic component which can be used as a respiratory matrix of the sulfate reducing bacteria. Therefore, the sulfuric acid reducing bacteria can be further activated by adding an organic material containing a large amount of crude protein. The upper limit of the content of the crude protein in the organic material is not particularly limited, and may be about 25% by mass.

The crude fat contained in the organic material is also decomposed by various bacteria into an organic component which can be used as a respiratory matrix of the sulfate reducing bacteria. Therefore, the content of crude fat is also preferred. In the present embodiment, the content of the crude fat in the organic material is preferably 2% by mass or more. The upper limit of the content of the crude fat in the organic material is not particularly limited, and may be about 20% by mass.

Since the crude fiber contained in the organic material is a residual component which is not decomposed by bacteria, it is preferable. In the present embodiment, it is preferable that the crude fiber contained in the organic material is 50% by mass or less. The lower limit is not particularly limited and can be set to about 5% by mass.

In the present embodiment, examples of the preferable organic material include distiller's grains, bean curd, rice bran, tea leaves, radix chinensis, tibia grass, and clover. These materials are easy to use and can be used directly without any processing on the starter.

Preferably, the cereal shell is placed in an anoxic state together with the pit effluent to culture a bacterial group associated with sulfate ion reducing activity containing a sulfate reducing bacteria. On the other hand, the organic material is preferably added after the culture.

The third step may be set as a continuous water passing step, that is, the pit wastewater is continuously introduced into the second container, and the pit water retained for a certain period of time is continuously discharged from the second container. Thereby, heavy metal ions can be continuously removed from the pit water.

The residence time of the pit water in the second container, the amount of the filler relative to the amount of the pit water, and the like can be appropriately set according to the concentration of the metal ions contained in the pit wastewater, the concentration of the target metal ions, and the like.

Here, the pit wastewater to be the object in the present embodiment is preferably a mine pit water flowing through a pit water conduit for collecting sediment in the first step. The reason for this is that if the present invention is practiced in a pit wastewater treatment plant where sediment is collected, there is no need to carry the transportation cost of the sediment. Further, the reason is that the iron oxidizing bacteria in the precipitate have the highest iron oxidation activity in the pit water flowing through the pit drainage water conduit which is precipitated by the precipitate.

(Purification System of Mine Wastewater) Next, an embodiment of the purification system of the pit water of the present invention will be described. 1 is a schematic view of a pit water purification system 100 according to an embodiment of the present invention.

First, the configuration for performing the first step and the second step (removal of divalent iron ions) will be described. The collected sediment 12 is filled in a column 10 as a container.

The supply system for continuously introducing the pit water into the column 10 includes a tank 14 for containing the pit water and a supply pipe 16 for introducing the pit water into the column 10. In addition, the discharge system in which the pit water remaining in the column 10 for a certain period of time is continuously discharged from the column 10 includes the discharge pipe 18. The discharged pit water is contained in the second tank 30. In the present embodiment, during the process in which the pit water is retained in the column 10 for a certain period of time, the iron oxidizing bacteria contained in the pit water and the iron oxidizing bacteria originally contained in the precipitate 12 act from the pit. The ferrous iron is removed from the wastewater.

Next, the configuration for performing the third step (removal of heavy metal ions other than divalent iron ions) will be described. The column 20 containing the sulfuric acid reducing bacteria is filled in the column 20 of the closed system as the second container. The column 20 of Fig. 1 is a state in which a sulfate-reducing bacteria is cultured inside, and a state in which an organic material is contained is added thereafter. Reference numeral 22 denotes a mixture of a cereal shell and a limestone, and reference numeral 24 denotes a cereal shell, a later-added organic-containing material, and a mixture of limestone.

As described above, in the present embodiment, the cereal shell is distributed throughout the tubular string 20, and the additional organic material is distributed only in the upper portion of the tubular string 20. However, the organic matter generated by the decomposition of the organic material in the upper portion of the column 20 is supplied to the entire column 20 by the flow of the pit water when the water is continuously supplied, so that the entire sulfuric acid in the column 20 can be reduced. Bacterial activation.

The limestone is preferably added as a pH buffer material when purifying acidic treated water having a pH of about 3.5 to 5.0.

The second supply system 28 that continuously introduces the pit wastewater into the column 20 includes a second tank 30, a second supply pipe 32, and a diaphragm pump 34 that accommodate the pit wastewater discharged from the column 10. The second supply pipe 32 connects the second groove 30 to the upper portion of the column 20. The diaphragm pump 34 is driven to supply the pit water in the second tank 30 to the inside of the column through the second supply pipe 32 from the upper supply port of the column 20.

The discharge system that continuously drains the pit water in the column 20 for a certain period of time from the column 20 includes a second discharge pipe 36. The second discharge pipe 36 is coupled to the discharge port of the pipe string 20 to be drained at the same level as the water level in the pipe string. Further, five water collecting holes 26A to 26E are provided in the column 20 to periodically sample the water to be treated in the column.

In the third step, the column 20 is maintained in an anoxic state, and the filling material in the column 20 continues to pass into the pit wastewater. During the movement of the pit water from the upper portion of the column 20 to the lower portion, the sulfide of the metal ions in the pit wastewater is precipitated, and the metal ions are removed from the water to be treated. Example

The precipitate of iron hydroxide oxide precipitated in the pit drainage water conduit from the pit of a mine to the pit wastewater treatment plant is collected. The collected precipitate is shown in Figure 2. The appearance of the precipitate is pumice. The precipitate was dried at 14.0149 g, and as a result, it was 7.7210 g, so that the water content was 55.1%.

The precipitate was subjected to composition analysis as follows. First, X-ray diffraction measurement was performed using the dried precipitate. Peaks were observed around 36° and 27°, and the results of the database search revealed the presence of iron hydroxide (FeO(OH)) and Hematite (Fe ₂ O ₃ ). Further, the dried precipitate was dissolved in an acid, and the concentration was measured using an inductively coupled plasma atomic emission (ICP-AES). The element content (% by mass) of the precipitate was Fe: 61.4%, Zn: 0.009%, Cu: 0.043%, Al: 0.116%, Mn: 0.005%, Cd: 0.002%, Ca: 0.534%, Mg: 0.134%, Si: 0.116%, residue: 37.6%. Thereby, the main component of the precipitate is iron, and the metal elements other than iron are all impurity levels of less than 1% by mass. The unidentified residue is presumed to be a hydroxide ion of iron hydroxide or a biofilm derived from microorganisms (organic hydrocarbon) in view of the formation process of the precipitate.

DNA was extracted from the collected precipitate (undried), and analyzed by a clone library method, and as a result, Steroidobacter denitrificans, Ferrovum myxofaciens, and Ma Lizhou vine were detected as ferric oxidizing bacteria. Luteibacter yeojuensis, Dokdonella sp, Acidisphaera sp, Leptospirillum ferriphilum.

Prepare a rectangular parallelepiped vinyl chloride column with a bottom area of 900 cm ² (30 cm × 30 cm) and a height of 45 cm. As the first step of the experiment, the collected pellet (not dried) was filled in the column by about 15 kg. Purification of the pit water was carried out in the following order by the experimental apparatus shown on the left side of FIG.

In this experiment, the pit water flowing through the pit drainage water conduit where the sediment is collected is used as a purification target. It is well known that the mine waste water also contains various iron oxide bacteria.

The pit wastewater is introduced into the column by a diaphragm pump. It is assumed that the pit wastewater is continuously introduced into the column, and the pit water is continuously discharged from the column, and the residence time is about 2 hours. This is the second step of the experiment.

The uranium ion concentration and the total iron concentration in the pit wastewater before being introduced into the column and the pit water discharged from the column are periodically measured by the morphine coloring method. The results are shown in Figures 3 and 4. As shown in Fig. 3, by this test, the ferrous ions in the pit wastewater are reduced from about 35 mg/L to 40 mg/L to approximately zero, and the state lasts for more than 250 days. In addition, as shown in Figure 4, the total iron concentration can also be reduced to less than 10 mg / L. This is considered to be a result of oxidizing divalent iron ions in the pit wastewater to precipitate iron compounds by the action of iron oxidizing bacteria contained in the pit water and iron oxidizing bacteria originally contained in the precipitate.

The pit water discharged in the second step is stored in a rectangular parallelepiped column with a bottom area of 400 cm ² (20 cm × 20 cm) and a height of 30 cm. The third step is then carried out, that is, the purification of the pit wastewater by the action of the sulfate reducing bacteria. Specifically, a large column test was carried out under natural temperature conditions using a biological purifying agent using rice husks and rice bran. The rice husk is directly used after being unsealed by a disc rice milling machine and stored in a dry state without any pulverization. Sulfuric acid reducing bacteria are attached to the rice husk. Rice bran is used as a powder which is discharged from a disc rice mill and stored in a dry state, and is used without any processing.

A test apparatus shown on the right side of Fig. 1 was assembled using a cylindrical vinyl chloride column having a diameter of 25 cm and a height of 110 cm. The column was filled with 4.275 kg of rice husk, and a mixture of 17.5 g of topsoil and 18 kg of limestone collected from the site as a source of bacteria. 35 L of treated water was added thereto, and it was allowed to stand in an anoxic state at a water temperature of 15 ° C to 25 ° C for 10 days. After 10 days, the Oxidation Reduction Potential (ORP) value was -200 mV to -300 mV, and the sulfate-reducing bacteria were activated, and the inside of the column became a reducing environment.

Thereafter, a mixture of 1.5 kg of rice bran and 0.225 kg of rice husk was added to the upper portion of the column.

The pit wastewater discharged in the second step was pumped and passed through the column for a residence time of 50 hours. Furthermore, the temperature of the pit water is not managed, and the environment in which the column is placed is also set to a natural temperature environment. The total metal concentration (including metal ions and all other metals) of various metals introduced into the pit from the beginning of the experiment into the column (the pit wastewater discharged in the second step) and the pit wastewater discharged from the column The concentration of the compound and the sulfate ion concentration are shown in Table 1.

As shown in Table 1, even after 251 days from the start of the test, the concentrations of various metals were sufficiently lowered. This is considered to be a result of the action of the sulfate reducing bacteria. [Industrial availability]

The method for purifying the pit water according to the present invention, the purification system of the pit water and the purifying agent for the pit water can remove the divalent iron ions contained in the pit wastewater more efficiently and at low cost.

10‧‧‧Pipe (container)
12‧‧‧ Iron Oxide Sediment
14‧‧‧ slot
16‧‧‧Supply tube
18‧‧‧Draining tube
20‧‧‧Pipe column (second container)
22‧‧‧Crust and limestone
24‧‧‧ cereal shells, additional organic materials, and limestone
26A～26E‧‧‧Water intake hole
28‧‧‧Second supply system
30‧‧‧second slot
32‧‧‧Second supply tube
34‧‧‧ diaphragm pump
36‧‧‧Second discharge pipe
100‧‧‧Purification system

1 is a schematic view of a purification system of a mine waste water according to an embodiment of the present invention. Figure 2 is a photograph of the precipitate used in the examples. Fig. 3 is a graph showing temporal changes in the concentration of divalent iron ions in the pit water before the introduction into the column and the pit water discharged from the column. 4 is a graph showing temporal changes in total iron concentration in pit wastewater before being introduced into a pipe string and in pit water discharged from a pipe string.

10‧‧‧Pipe (container)

12‧‧‧ Iron Oxide Sediment

14‧‧‧ slot

16‧‧‧Supply tube

18‧‧‧Draining tube

20‧‧‧Pipe column (second container)

22‧‧‧Crust and limestone

24‧‧‧ cereal shells, additional organic materials, and limestone

26A~26E‧‧‧ water intake hole

28‧‧‧Second supply system

30‧‧‧second slot

32‧‧‧Second supply tube

34‧‧‧ diaphragm pump

36‧‧‧Second discharge pipe

100‧‧‧Purification system

Claims (8)

A method for purifying mine pit water, comprising: a first step of collecting iron oxide hydroxide precipitate deposited in a pit drainage conduit from a pit of a mine to a pit wastewater treatment plant, and filling the container; and In a second step, the pit wastewater is introduced into the vessel and retained, whereby the ferrous iron in the pit wastewater is treated by the action of iron oxidizing bacteria originally contained in the iron hydroxide hydroxide precipitate. The iron compound is precipitated by ion oxidation to remove the divalent iron ions from the pit wastewater. The method for purifying a pit water according to claim 1, wherein the second step is a continuous water passing step, continuously introducing the pit wastewater into the container, and retaining the pit wastewater for a specific time. Continued discharge from the container. The method for purifying a pit water according to claim 2, further comprising a third step of introducing the pit water discharged in the second step into a second container filled with a carrier retaining sulfuric acid reducing bacteria Internally maintaining the second container in an oxygen-deficient state and retaining the pit waste water, thereby utilizing the action of the sulfuric acid reducing bacteria to cause heavy metal ions other than the divalent iron ions in the pit wastewater Sulfide precipitates, thereby removing the heavy metal ions from the pit wastewater. The method for purifying a pit water according to claim 3, wherein the third step is a continuous water passing step, continuously introducing the pit wastewater into the second container, and the remaining time is retained. The pit water is continuously discharged from the second container. The method for purifying a pit wastewater according to any one of claims 1 to 4, wherein the pit water is a pit water flowing through a water conduit of the pit water. A mine pit purification system characterized by: a container filled with an iron hydroxide precipitate precipitated in a pit drainage conduit from a pit of a mine to a pit wastewater treatment plant; a supply system, said Continuously introducing the pit water into the container; and discharging the system, which is retained in the container for a specific period of time, and the divalent iron ions are acted by the action of iron oxidizing bacteria originally contained in the iron hydroxide hydroxide precipitate The removed pit water continues to drain from the vessel. The mine pit purification system according to claim 6, further comprising: a second container filled with a carrier retaining sulfuric acid reducing bacteria and maintaining an anoxic state; and a second supply system from the discharge system The discharged pit water is continuously introduced into the second container; and the second discharge system is retained in the second container for a specific time and the ferrous iron is acted by the sulfuric acid reducing bacteria The pit water from which heavy metal ions other than ions are removed continues to be discharged from the second container. A purifying agent for mine pit water, which is a purifying agent for removing pit water of the divalent iron ion from a pit wastewater containing divalent iron ions, characterized in that it contains iron oxidizing bacteria and contains collected precipitates Iron oxyhydroxide precipitate in the pit drainage conduit from the pit of the mine to the pit wastewater treatment plant.