JP4235094B2 - Metal mine drainage treatment method and valuable metal recovery method - Google Patents

Description

  The present invention relates to a method for treating metal mine drainage containing acid and heavy metals and / or a method for treating sludge generated during treatment of metal mine wastewater.

  Since metal mines mainly mine sulfide minerals, minerals such as pyrite, chalcopyrite, and sphalerite remain after mining, and these react with oxygen in groundwater and air to produce acid and heavy metal-containing mine drainage. appear. This mine drainage is neutralized by a neutralizing agent such as slaked lime, and then subjected to solid-liquid separation in a sedimentation basin. The supernatant water is discharged and the sediment is dehydrated and discarded. Although this dewatered sludge contains a large amount of iron, it contains impurities such as arsenic, copper, and zinc, and has a high moisture content of 60 to 80%, so it cannot be used as an iron source in the steel industry.

  In addition, the dewatered sludge is stored in a predetermined storage location, but its storage capacity is reduced, and a new storage location is required.

  Under such circumstances, Patent Document 1 discloses that a liquid in which an alkali liquid and a flocculant are mixed is supplied to a precipitation tank, a slurry containing a metal hydroxide precipitated in the precipitation tank is taken out, and an alkaline waste liquid is added to the slurry. Is added to the waste liquid containing metal ions in the neutralization tank, and the metal hydroxide particles produced by the neutralization of the waste liquid are enlarged, and the precipitation rate in the settling tank The size of sedimentation basins such as thickeners and processing efficiency are improved.

  In addition, as an example of the sludge treatment that has already occurred, Patent Document 2 describes that after neutralizing Ni or Zn, Ni-containing waste liquid, the precipitates are agglomerated and separated, and the agglomerated and separated sludge is dehydrated, and then the Acid dissolved with a mineral acid such as sulfuric acid, nitric acid, hydrofluoric acid, etc., and separated into iron and Ni or Zn, Ni-containing solution, neutralize the solution, and separate precipitates containing Ni, Zn, or Ni It is described. At the time of acid dissolution with this mineral acid, if Ni or Zn, Ni is to be separated with high efficiency, it is necessary to lower the pH to 1 or less in order to dissolve almost all of the trivalent iron compound.

JP-A-4-267994 Japanese Patent Laid-Open No. 7-97643

  However, in the method disclosed in Patent Document 1, although the metal hydroxide particles can be enlarged to some extent, the bond is mainly caused by the polymer flocculant to agglomerate the particles with each other, so that a weak force such as stirring is applied. In this case, lumps of metal hydroxide are easily separated, and large metal hydroxide particles cannot be stably formed, which increases the cost of chemicals such as aggregating agent.

  Moreover, since the density of the metal hydroxide in the particles is small and the particles are easily broken, when the slurry containing the precipitated metal hydroxide particles is dehydrated, the water content of the dewatered sludge is 55 to 70. The mass becomes high.

  Therefore, since the density of the particles cannot be increased so much, the sedimentation rate in the sedimentation basin (sedimentation tank) is also slowed down, the sedimentation tank such as thickener is enlarged, and the efficiency of precipitation and dehydration is reduced.

  Furthermore, the metals contained in the waste liquid are included when the metal hydroxides of arsenic, copper, and zinc are mixed and precipitated in addition to iron by the neutralization treatment and reused as resources. There is a problem that other metal hydroxides become an obstacle and iron in the metal hydroxides cannot be used effectively.

  Moreover, in the method disclosed in Patent Document 2, in order to dissolve all iron in the sludge as trivalent iron ions, the pH may be lowered to less than 1 so that many trivalent iron ions are dissolved. Is required and requires a lot of mineral acid.

  The present invention has been made in view of such circumstances, and sludge generated during metal mine drainage treatment is a pH region where trivalent iron ions are partially dissolved, and partially ionized trivalent iron ions are used as a reducing agent. By reducing to divalent iron ions with greater solubility, the solution was made without significantly lowering the pH, and the amount of mineral acid required for this was reduced, and the solution was separated. After that, by mixing with the metal mine drainage, and adjusting the pH of the mixed drainage in several stages, the metal hydroxide to be deposited is separated for each type, thereby selectively selecting iron (III) hydroxide. In order to be used as an iron source in the iron and steel industry by forming large particles, the content of impurities that adversely affect the stable operation of the iron making process and the quality of steel products is low and the moisture content is low. Dehydrated dirt An object is to provide a method for producing mud.

In order to solve the above-mentioned object, the present inventor is a method for treating sludge containing arsenic and copper and / or zinc and trivalent iron, and a metal mine drainage containing arsenic , copper and / or zinc in addition to iron ions. As a result of intensive studies on a method for selectively separating iron (III) hydroxide, forming large particles and producing dehydrated sludge having a low water content, a pH region in which iron (III) hydroxide is partially dissolved Then, the partially ionized trivalent iron ion is reduced with a reducing agent and reduced to a divalent iron ion having a higher solubility, thereby forming a solution without significantly lowering the pH. Is separated by solid-liquid separation, the liquid is mixed with the metal mine drainage, the pH of the mixed wastewater is adjusted in multiple stages, and the mixed wastewater is deposited on the surface of the metal hydroxide deposited according to the adjusted pH. Particles in contact with metal ions inside The larger, by dehydrating a metal hydroxide having a particle diameter is large, with a low moisture content, and found that it is possible to produce a dewatered sludge separating the metal component by type. Among them, it was found that dehydrated sludge having a low water content mainly composed of iron hydroxide (III) can be used as an iron source in the steel industry. That is, the present invention has been made based on the above findings, and the gist thereof is as follows.

(1) A method for treating mine drainage containing divalent iron ions and / or trivalent iron ions as acidic heavy metals generated from a metal mine , and containing arsenic ions ,
In the metal mine drainage, when the trivalent iron ion concentration is more than 1 time in terms of molar concentration with respect to the pentavalent arsenic ion concentration, the metal mine drainage is put into a second container, If the concentration of trivalent iron ions in the metal mine drainage is less than 1 time in terms of molar concentration with respect to the pentavalent arsenic ion concentration, the stock solution of the compound consisting of the metal mine drainage and trivalent iron ions is used. Put in the tank and adjust the trivalent iron ion concentration to 1 to 3 times in terms of molar concentration with respect to the pentavalent arsenic ion concentration. To
In the second container, the pH of the waste water is controlled to 3 to 5 to precipitate a compound of arsenic and trivalent iron ions, and then the precipitate is subjected to a solid-liquid separation process. Into a third container,
In a third vessel, to control the pH of the drainage 6-10, blowing air, after precipitating iron hydroxide and at the same time to oxidize the bivalent iron ions to trivalent iron ions, leaving the precipitation A method for treating metal mine drainage, comprising sequentially performing a solid-liquid separation process and discharging a liquid component.

(2) Treatment of mine drainage containing divalent iron ions and / or trivalent iron ions as acid and heavy metals generated from a metal mine, containing arsenic ions, and further containing copper ions and / or zinc ions A method,
In the metal mine drainage, when the trivalent iron ion concentration is more than 1 time in terms of molar concentration with respect to the pentavalent arsenic ion concentration, the metal mine drainage is put into a second container,
In the metal mine drainage, when the trivalent iron ion concentration is less than 1 time in terms of molar concentration with respect to the pentavalent arsenic ion concentration, a compound composed of the metal mine drainage and trivalent iron ions is added. Put into the stock solution tank and adjust the trivalent iron ion concentration to 1 to 3 times in terms of molar concentration with respect to the pentavalent arsenic ion concentration. In the second container, the pH of the waste water is controlled to 3 to 5, the compound of arsenic and trivalent iron ions is precipitated, and then the precipitate is solid-liquid separated. And put the liquid into a third container,
In the third container, the pH of the waste water is controlled to 3-5, iron-oxidizing bacteria are added, air is blown in, and bivalent iron ions are oxidized to trivalent iron ions, while iron hydroxide is deposited. Then, the precipitate is subjected to a solid-liquid separation process, and the liquid is put into a fourth container, and
In a fourth container, the pH of the waste water is controlled to 6 to 10, and copper and / or zinc is deposited as metal hydroxide in order to treat the metal mine waste water Method.

( 3 ) The divalent iron ion mass concentration in the wastewater discharged from the third container is 150 mg / L or less, or the first concentration relative to the mass concentration of iron in the wastewater discharged from the second container. 3. The method according to (1) or (2) , wherein the ratio of the divalent iron ion mass concentration in the waste water discharged from the container 3 is 0.12 or less.

( 4 ) The divalent iron ion mass concentration in the wastewater discharged from the third container is 20 mg / L or less, or the first concentration relative to the mass concentration of iron in the wastewater discharged from the second container. 3. The method according to ( 3 ), wherein the ratio of the divalent iron ion mass concentration in the wastewater discharged from the container 3 is 0.02 or less.

( 5 ) The ratio of the total mass of zinc ions and copper ions precipitated in the third container to the mass of iron ions precipitated in the third container is 0.1 or less (2 ) Method.

( 6 ) The ratio of the total mass of zinc ions and copper ions precipitated in the third container to the mass of iron ions precipitated in the third container is 0.01 or less ( 5 ) Method.

( 7 ) Metal whose particle size is increased by stirring the waste water in at least one of the second to fourth vessels, bringing the metal compound particles into contact with the deposited metal compound particles, and increasing the particle size. The method according to any one of ( 1 ) to ( 6 ), wherein the compound is dehydrated.

( 8 ) The method according to any one of ( 1 ) to ( 7 ), wherein the wastewater in the container is filtered using a separation membrane in at least one of the second to fourth containers.

( 9 ) The method according to ( 8 ), wherein the pore size of the separation membrane is 1 to 100 μm.

( 10 ) A neutralized precipitate generated when neutralizing acidic wastewater from a metal mine and water or acidic water are mixed in a fifth container to form a slurry, and the pH of the slurry is 1 or more. 5 or less, a reducing agent is charged into the container, trivalent iron ions are reduced to divalent iron ions, solid-liquid separation is performed, and the liquid is charged into the first container. as heavy metals in acidic generated from mines contains divalent iron ions and / or trivalent iron ions, and arsenic ions are mixed in the mine effluent I containing, divalent part of iron ions of the exhaust water The waste water is put into a second container, and the pH of the waste water is controlled to 3 to 5 in the second container to arsenic and trivalent. The iron ion compound is precipitated, and then the precipitate is subjected to a solid-liquid separation treatment. In a third container, the pH of the waste water was controlled to 6 to 10, and air was blown in to oxidize divalent iron ions to trivalent iron ions and precipitate iron hydroxide at the same time. Thereafter, a process for solid-liquid separation of the deposit and sequentially discharging the liquid component are performed .

( 11 ) A neutralized precipitate generated when neutralizing acidic wastewater from a metal mine and water or acidic water are mixed in a fifth container to form a slurry, and the pH of the slurry is 1 or more. 5 or less, a reducing agent is charged into the container, trivalent iron ions are reduced to divalent iron ions, solid-liquid separation is performed, and the liquid is charged into the first container. Mixed with mine drainage containing divalent iron ions and / or trivalent iron ions as acidic and heavy metals generated from the mine, containing arsenic ions, and further containing copper ions and / or zinc ions, After performing a treatment for oxidizing a part of the divalent iron ions in the wastewater to trivalent iron ions, the wastewater is put into the second container, and the pH of the wastewater is adjusted to 3 in the second container. After controlling to ˜5 and precipitating a compound of arsenic and trivalent iron ions, The precipitate is subjected to solid-liquid separation, and the liquid is put into a third container. In the third container, the pH of the waste water is controlled to 3 to 5, iron-oxidizing bacteria are added, and air is supplied. Blowing, oxidizing the divalent iron ions to trivalent iron ions and precipitating iron hydroxide at the same time, then subjecting the precipitate to solid-liquid separation, putting the liquid into a fourth container, and In the fourth container, the pH of the waste water is controlled to 6 to 10, and at least one element of copper and zinc is sequentially deposited as a metal hydroxide, and a method for treating metal mine waste water .

( 12 ) At least one of dust generated from a smelting furnace in the steel industry, a scale generated when rolling in the steel industry, and cutting scraps as a reducing agent is used in ( 10 ) or ( 11 ) The method described.

( 13 ) The method according to (12), wherein the metal iron used as the reducing agent has a specific surface area of 10 cm ² / g or more.

( 14 ) The method according to any one of ( 10 ) to ( 13 ), wherein metal mine drainage is used as the acidic water to be charged into the fifth container.

( 15 ) A method for recovering valuable metals in metal mine drainage, wherein the metal hydroxide precipitated by the method according to any one of (1) to ( 14 ) is recovered as sludge.

  In the metal mine drainage treatment method of the present invention, partially ionized trivalent iron ions are reduced with a reducing agent in a pH range where iron (III) hydroxide in sludge generated during metal mine drainage treatment is partially dissolved. Then, by reducing it to divalent iron ions having a higher solubility, the solution was formed without significantly lowering the pH, and the liquid was separated by solid-liquid separation, which was acidic and contained heavy metals. While mixing with the metal mine drainage and continuously supplying the mixed wastewater into the container, the container is neutralized in the container to adjust the pH of the mine drainage in a plurality of stages. The metal hydroxide deposited according to the adjusted pH is brought into contact with metal ions to increase the particle size, and the metal hydroxide having a larger particle size is separated and recovered to obtain arsenic, copper, At least of zinc One or more elements can be separated and dehydrated from iron hydroxide consisting of iron, and iron-based dehydrated sludge having a low water content can be effectively used as an iron source in the steel industry.

The present invention will be described in detail below.
Processing method of metal mining waste water according to the present invention comprises a divalent iron ion and / or trivalent iron ions, and metal mining waste water containing arsenic ions, or a further copper ions and / or zinc ions metal mining waste water containing, as well as those containing arsenic and trivalent iron sludge generated during the metal mining waste water treatment, or further to a sludge containing copper and / or zinc and their processed.

  As shown in FIG. 1, it is obvious that coprecipitation with trivalent iron ions is necessary to deposit arsenic ions. Therefore, the pH of the metal mine drainage containing a part of divalent iron ions to trivalent iron ions and containing pentavalent arsenic ions, copper ions and zinc ions and the residual ratio of elements in the metal mine drainage FIG. 1 shows the relationship.

  From this figure, trivalent iron ions and pentavalent arsenic ions precipitate at pH 3 to 4, copper ions precipitate at pH 5 to 6, zinc ions and divalent iron ions precipitate at pH 6 to 10. Further, comparing trivalent iron ions with divalent iron ions, it can be seen that divalent iron ions have higher solubility under conditions of pH 7 or lower. In other words, when a trivalent iron compound is dissolved in the state of trivalent iron ions, the solubility is immediately restricted and the dissolution does not proceed, but the dissolved trivalent iron ions are divalent with high solubility. By reducing to the iron ions, dissolution becomes easier.

  Next, when wastewater containing arsenic, copper, zinc and trivalent iron is neutralized, the deposited precipitate is treated, metallic iron is used as a reducing agent, and trivalent iron ions are reduced. FIG. 2 shows the relationship between the dissolution rate of heavy metals and the amount of iron input. Trivalent iron compounds that have been precipitated around the compound consisting of arsenic, copper, and zinc in the precipitate by reducing trivalent iron ions to high-solubility divalent iron ions by metallic iron It can be seen that almost all are dissolved, and heavy metals of arsenic, copper, and zinc are dissolved.

The specific surface area of the metallic iron used is preferably 10 cm ² / g or more (measured by the BET method). When the specific surface area is 10 cm ² / g or less, the reactivity is poor. Therefore, in order to increase the reaction rate, the amount of iron to be input increases, which is not realistic.

As metallic iron, at least one or more of iron powder, dust generated from a refining furnace in the manufacturing industry, scale generated when rolling in the steel industry, cutting waste, and waste blasting material can be used.
The pH in the reaction vessel is controlled to 1 or more and 5 or less, preferably 1 or more and 3 or less. When the pH is 1 or less, a large amount of mineral acid is required, and when the pH is 5 or more, the trivalent iron ions are hardly dissolved and the reduction reaction itself is difficult to proceed.

  Therefore, in order to separate and recover the sludge generated during the neutralization of metal mine drainage and / or iron in the metal mine drainage, first mix the sludge with water or acidic water in a container. Then, sludge is slurried, the trivalent iron ions are reduced to highly soluble divalent iron ions with a reducing agent such as iron powder in the fifth container, and solid-liquid separation is performed. Mixing with acid and heavy metal mine drainage generated from the mine, charging the mixed water into the first container, oxidizing part of the divalent iron to trivalent, and controlling to pH 3-5 The treated water in the first container is poured into the second container so that the compound of arsenic and trivalent iron is precipitated, and then the precipitate is solid-liquid separated, and the pH is controlled to 3-5. Add the iron-oxidizing bacteria and blow the air into the third container. In the fourth container controlled to pH 6-10, the step of oxidizing the divalent iron ions to trivalent and simultaneously depositing the iron compound and performing solid-liquid separation, It is necessary to have a step of depositing at least one element of copper and zinc by adding treated water in the container 3.

  Further, in order to use it as an iron source in the steel industry, it is necessary to reduce the moisture accompanying the metal hydroxide to be separated and recovered, in addition to the above-mentioned removal of impurities. On the other hand, the inventors stir in the second, third, and fourth containers to increase the particle diameter by bringing metal ions into contact with the deposited metal hydroxide particles to increase the particle diameter. It was found that a dehydrated cake having a low water content can be obtained by dehydrating the metal hydroxide having a large diameter. Furthermore, in order to stably increase the particle diameter in the third container in which iron (III) hydroxide is selectively separated, divalent iron ions in the treated water discharged from the third container are used. The mass concentration of 150 mg / L or less, or the ratio of the divalent iron ion mass concentration in the treated water discharged from the third container to the mass concentration of iron in the treated water discharged from the second container Is preferably adjusted to 0.12 or less.

  FIG. 3 shows the relationship between the divalent iron ion concentration in the filtered water filtered from the third container and the particle diameter in the third container in a steady state. The divalent iron ion mass concentration in the treated water discharged from the inside of the third container is 150 mg / L or less, or the iron mass concentration (T-Fe) in the treated water discharged from the second container. If the ratio of the divalent iron ion mass concentration in the treated water discharged from the container 3 is 0.12 or less, the average particle diameter of iron hydroxide (III) precipitated in the third container is 2 It becomes possible to control to ˜14 μm, and by increasing the average particle size, the dehydration rate of iron hydroxide (III) in the subsequent dehydration treatment is increased, and the porosity in the dewatered sludge is decreased, resulting in low It becomes possible to obtain dehydrated sludge having a water content. More preferably, the divalent iron ion mass concentration in the treated water discharged from the third container is 20 mg / L or less, or the first concentration relative to the mass concentration of iron in the treated water discharged from the second container. If the ratio of the divalent iron ion mass concentration in the treated water discharged from the vessel 3 is 0.02 or less, the average particle diameter of the precipitated iron hydroxide (III) should be controlled to 10 to 14 μm. By increasing the average particle size, the dehydration rate of iron hydroxide (III) in the subsequent dehydration process is increased, and the porosity in the dewatered sludge is reduced, so that sludge having a lower water content can be obtained. It becomes possible to obtain stably.

As a method for controlling the mass concentration of divalent iron ions in the metal mine drainage in the third container, iron-oxidizing bacteria are added to the metal mine drainage in the third container, and in the third container A method of oxidizing divalent iron ions to trivalent iron ions can be mentioned. As the iron-oxidizing bacteria, filamentous bacteria that grow in the neutral region, filamentous bacteria that grow in the acidic region, and non-filamentous bacteria can be used. For example, it is possible to use generally a non-filamentous bacteria growing in the acidic space used Thiobacillus-ferrooxidans is a chemical autotrophic bacteria (Thiobachillus ferrooxidans).

  FIG. 4 is a diagram showing the influence of copper / zinc ions on the particle diameter in the case where iron hydroxide (III) is precipitated and a small amount of copper and zinc ions are precipitated in the third container. It can be seen that when the ratio of the mass of precipitated copper and zinc ions to the mass of trivalent iron ions is 0 to 0.1, the average particle size of the metal hydroxide is 2 to 14 μm. Furthermore, if the said ratio is 0-0.01, it turns out that the average particle diameter of a metal hydroxide will be 10-14 micrometers. In other words, by adjusting the pH control value in the third container or diluting the metal mine drainage supplied to the third container, the ratio of the precipitated copper and zinc ions to the precipitated trivalent iron ion mass is determined. And as a result, the average particle size can be controlled.

Next, an embodiment embodying the present invention will be described.
FIG. 5 shows an example of a metal mine drainage treatment and valuable metal recovery apparatus according to the present invention.

  As shown in FIG. 5, the metal mine drainage treatment method and the valuable metal recovery device 10 applied to the metal mine drainage treatment method according to one embodiment of the present invention are at least one of arsenic, copper, and zinc. The sludge containing these elements and trivalent iron is put into the sludge storage tank 11 and put into the fifth container 13 by the cutting pump 12. In the fifth container 13, a part of diluted water or acidic metal mine drainage 14 is put together, and a stirrer 17, a pH meter 15, and an ORP meter 16 are installed. The sludge containing the elements of arsenic, copper, zinc and trivalent iron charged into the fifth container 13 is made into a slurry by the stirrer 17. Next, mineral acid 18 such as hydrochloric acid / sulfuric acid / nitric acid is added, and the pH meter 15 controls the pH in the fifth container to 1 or more and 5 or less, preferably 1 or more and 3 or less. At this time, a part of iron hydroxide (III) in the sludge is ionized and dissolved. Next, a reducing agent is extracted from the reducing agent storage tank 20 by a cutting pump 21 to reduce trivalent iron ions to divalent iron ions. In addition, as a reducing agent, it is possible to use at least one or more of an amine compound, iron powder, dust generated from a smelting furnace in the steel industry, scale generated when rolling in the steel industry, cutting waste, and waste blasting material. it can. The amount of reducing agent charged can be controlled by the ORP meter 16. For example, when the pH value is controlled at 2.5, most of the iron ions become divalent iron ions by introducing a reducing agent until the ORP value becomes 480 mV. Next, the liquid is sent to the solid-liquid separator 23 by the pump 22, the unreacted reducing agent is separated, and returned to the fifth container 13 again. On the other hand, the separated treatment liquid is mixed with the mine drainage 31 in the raw water tank 33 and is sent to the first container 34.

  A stone 35 or the like is installed in the first container 34, and a lid is installed on the upper part of the first container 34 so that air does not enter from the outside. Iron-oxidizing bacteria are put in advance. In the second container 34, iron-oxidizing bacteria use dissolved oxygen to oxidize a part of divalent iron ions in the mine drainage to trivalent. In order to control the oxidation amount of divalent iron ions and oxidize only a part, a dissolved oxygen concentration (DO) meter 32 installed in the raw water tank 33 is used, and air or nitrogen gas is introduced into the raw water tank 33. The dissolved oxygen concentration in the raw water tank is controlled by blowing. As a result, the action of oxidizing the bivalent iron of the iron-oxidizing bacteria living in the first container 34 to trivalent iron is restricted by the dissolved oxygen concentration, and only a part of the divalent iron is trivalent. Can be oxidized to iron. The trivalent iron ion concentration in the treated water discharged from the first container 34 may be 1 to 3 times in molar concentration with respect to the arsenic concentration. If it is less than 1 time, arsenic cannot be removed almost completely in the next second container 36. When the amount exceeds three times, the amount of iron (III) hydroxide precipitated in the second container 36 is reduced, and the target amount that can be an iron source in the steel industry is reduced. The concentration of arsenic in the compound of iron and arsenic deposited in the interior decreases, and the utility value as an arsenic raw material decreases.

  Further, as a method of oxidizing a part of the divalent iron ions in the first container 34, an oxidizing agent such as hydrogen peroxide solution, hypozinc acid, hexavalent chromium or the like is added, and chemical oxidation is performed. It can also be done.

  Next, the treated water discharged from the first container 34 is put into the second container 36. In the second container 36, there are a stirring blade 37 and a rectifying wall 38 for generating a circulating flow, and a filtrate is sucked from the membrane separator 39 for performing solid-liquid separation and the membrane separator 39. A suction pump 40 is installed. The circulation flow rate is preferably in the range of 0.3 to 3 m / sec. If it is less than 0.3 m / sec, a deposit accumulates in the bottom part of the 2nd container 36, and a blockade is caused. On the other hand, if it exceeds 3 m / sec, the power cost for forming the circulation flow increases, which is not economical. No oxygen or air is blown into the second container 36. The treated water from the first container 34 charged into the second container 36 is neutralized to 3 to 5 with an alkaline agent such as caustic soda, calcium carbonate, slaked lime or magnesium hydroxide. By this neutralization action, trivalent iron ions and pentavalent arsenic ions oxidized in the first container 34 are precipitated. In addition, pentavalent arsenic ions and trivalent iron ions are precipitated on the surface of the precipitated particles, thereby increasing the particle diameter. However, the divalent iron ions are in a dissolved state and do not precipitate in the second container 36. The arsenic and iron compound having a large particle diameter is discharged from a slurry discharge pipe (not shown). Excess water in the second container 36 is filtered by the membrane separation device 39 and sucked by the suction pump 40, and the filtered water is put into the next third container 41.

In the third container 41, there is an air diffuser 43 for sending air or oxygen into the third container 41 and a rectifying wall 42 to form a circulating flow. The amount of air or oxygen for forming the circulating flow is preferably 0.003 to 0.2 Nm ³ / m ³ / min per unit volume, although it depends on the size of the third container 41. If it is less than 0.003 Nm ³ / m ³ / min, the precipitated metal hydroxide particles settle and deposit on the bottom of the third container 41, and power exceeding 0.2 Nm ³ / m ³ / min is used for blowing air. Is too economical. Further, a membrane separation device 44 for performing solid-liquid separation and a suction pump 45 for sucking filtered water from the membrane separation device 44 are installed. The divalent iron ions in the treated water from the second container 36 introduced into the third container 41 are converted into trivalent iron ions by iron-oxidizing bacteria and dissolved oxygen introduced into the third container 41. The pH is neutralized to 3 to 5 using an alkali agent such as caustic soda, calcium carbonate, slaked lime or magnesium hydroxide, or an acid agent such as sulfuric acid. Preferably, the pH is neutralized to 3-4. In particular, when copper ions are contained in the mine drainage at 40 mg / L or more, the separation performance of copper and iron increases when the pH in the third container 41 is controlled to 3-4. As a result, most of the trivalent iron ions are precipitated as iron hydroxide. Trivalent iron ions are brought into contact with the precipitated iron hydroxide particles to be precipitated on the particle surface, thereby increasing the particle diameter. The iron hydroxide having an increased particle size is discharged from a slurry discharge pipe (not shown). The surplus water in the third container 41 is filtered by the membrane separation device 44 and sucked by the suction pump 45, and the filtered water is put into the next fourth container 46.

In the fourth container 46, there are an air diffuser 48 and a rectifying wall 47 for sending air into the fourth container 46, and a circulation flow is formed. The amount of air or oxygen for forming the circulating flow is preferably 0.003 to 0.2 Nm ³ / m ³ / min per unit volume, although it depends on the size of the fourth container 46. If it is less than 0.003 Nm ³ / m ³ / min, the precipitated metal hydroxide particles settle and deposit on the bottom of the fourth container 46, and power exceeding 0.2 Nm ³ / m ³ / min is used for blowing air. Is too economical. Further, a membrane separation device 49 for performing solid-liquid separation and a suction pump 50 for sucking filtered water from the membrane separation device 49 are installed. The treatment from the third container 41 introduced into the fourth container 46 neutralizes the pH to 6 to 10 using an alkaline agent such as caustic soda and slaked lime. By this neutralization treatment, copper and zinc ions contained in the treatment liquid from the third container 41 are deposited as metal hydroxide. Copper metal ions such as copper and zinc ions are brought into contact with the precipitated metal hydroxide particles to be precipitated on the particle surface, thereby increasing the particle diameter. The metal hydroxide having an increased particle size is discharged from a slurry discharge pipe (not shown). The surplus water in the fourth container 46 is filtered by the membrane separation device 49 and sucked by the suction pump 50, and the filtered water is discharged.

  The membrane separators 39, 44 and 49 are made of a material made of polypropylene, polyester, polyvinylidene chloride, polyacryl, polyvinyl alcohol or the like, and have a pore diameter of 1 to 100 μm. When the pore diameter is smaller than 1 μm, fine particles of metal hydroxide are clogged and the filtration rate is remarkably reduced. On the other hand, when the pore diameter is larger than 100 μm, the number of particles passing through the pores of the separation membrane increases, the separation performance of heavy metal components contained in the metal mine drainage is deteriorated, and the iron recovery efficiency is lowered.

  Moreover, the slurry discharged from the second, third and fourth containers (36, 41, 46) is dehydrated and processed into dehydrated sludge. Examples of the dehydration method include a method of dehydrating using a dehydrator such as a filter press, a vacuum dehydrator, and a centrifugal dehydrator, and a method of dehydrating by sun drying. The dehydrated sludge that has been dehydrated can be used effectively as a resource, and in particular, the dehydrated sludge made of iron hydroxide (III) from the third container can be used as an iron source in the steel industry.

In addition, the target amount of treated water in the first, second, third, and fourth containers (34, 36, 41, 46) is preferably 6 to 3000 m ³ / h. When it is less than 6 m ³ / h, the target water amount is small, and the merit for the investment amount for carrying out the present invention is small and not economical. On the other hand, if it exceeds 3000 m ³ / h, the solid-liquid separator becomes too large to maintain a stable operation of the solid-liquid separator.

  Moreover, the target amount of the sludge treatment method containing at least one element of arsenic, copper, and zinc and trivalent iron generated during the metal mine drainage treatment is the first, second, third, and fourth containers. 4 mass% (wet state) or less of the amount of treated water in is preferable. This is because if it is 4% by mass or more, the metal ion concentrations in the second, third, and fourth are increased, and the element separability is lowered.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and all changes in conditions and the like that do not depart from the gist are within the scope of the present invention.

  For example, in the second, third, and fourth containers, the membrane separation device is shown in FIG. 5 as the solid-liquid separation device, but the solid-liquid separation device using a sedimentation basin is also sufficiently effective.

  Further, when the trivalent iron ion concentration in the raw water of the metal mine drainage is 1 or more (molar concentration standard) with respect to the pentavalent arsenic ion concentration, the first container can be dispensed with.

  In addition, when the trivalent iron ion concentration in the raw water of the metal mine drainage is less than one time (molar concentration standard) with respect to the pentavalent arsenic ion concentration, the raw water tank is composed of trivalent iron ions. Compound, for example, ferric sulfate, ferric chloride, neutralized starch that has been generated mainly by iron (III) hydroxide, and trivalent iron ion concentration is pentavalent to arsenic ion concentration, It is also possible to adjust the molar concentration so as to be 1 to 3 times, and to put it directly into the second container.

  Further, when the metal mine drainage contains iron and arsenic ions and does not contain zinc ions and copper ions, or the iron hydroxide precipitated in the third container 41 with only a small amount of zinc ions and copper ions contained therein. When there is no problem in terms of components in recycling, the operation of separating zinc ions and copper ions from iron ions is unnecessary, and the fourth container 46 is unnecessary. That is, for metal mine drainage containing iron and arsenic ions but not containing zinc ions and copper ions, the metal mine drainage is put into the first container and a part of the divalent iron ions in the drainage. The waste water is put into a second container, and the pH of the waste water is controlled to 3 to 5 in the second container to arsenic and trivalent. After the iron ion compound is deposited, the precipitate is subjected to a solid-liquid separation treatment, and the liquid is put into a fourth container, and the pH of the waste water is adjusted to 6 to 10 in the third container. Controlling, blowing air, oxidizing divalent iron ions to trivalent iron ions and precipitating iron hydroxide at the same time, then subjecting the precipitate to solid-liquid separation to discharge the liquid it can.

Also, when iron mine drainage contains iron and zinc or / and copper ions and does not contain arsenic ions, or contains only a small amount of arsenic ions, iron hydroxide deposited in the third container 41 is recycled. On the other hand, when there is no problem in terms of components, the operation of separating arsenic is unnecessary, and the first container 34 and the second container 36 are unnecessary. That is, for a mine drainage containing iron and zinc or / and copper ions and not containing arsenic ions, the metal mine drainage is charged into a third container, and the pH of the drainage in the third container. Is controlled to 3-5, iron-oxidizing bacteria are added, air is blown, and divalent iron ions are oxidized to trivalent iron ions, and at the same time iron hydroxide is precipitated, and the precipitate is separated into solid and liquid. The liquid is put into a fourth container, and the pH of the waste water is controlled to 6 to 10 in the fourth container, and copper and / or zinc elements are precipitated as metal hydroxides. Thereafter, the precipitate is subjected to a solid-liquid separation treatment, and the liquid component can be discharged.

Next, Ru Reference Examples method of processing metal mining effluent of the present invention.

This example is a reference example conducted in a laboratory experiment while correlating with real metal mine drainage.

( Reference Example 1)
As the metal mine drainage, a solution containing divalent iron ions, trivalent iron ions, pentavalent arsenic ions, copper ions and zinc ions shown in Table 1 is used. The metal mine drainage was treated using a container. The capacities of the first container, the second container, the third container, and the fourth container are 0.6L, 1L, 3L, and 3L, respectively.

  Air was blown into the metal mine drainage 31 in the raw water tank 33 to control the dissolved oxygen concentration in the metal mine drainage to 4 mg / L, and this was continuously supplied to the first container 34 at 20 mL / min. A stone having a diameter of 3 to 10 mm is installed in the first container 34 to immobilize iron-oxidizing bacteria. This iron-oxidizing bacterium oxidizes divalent iron ions to trivalent utilizing dissolved oxygen in the metal mine drainage, but only some of the divalent iron ions are oxidized by the dissolved oxygen rate limiting.

  Next, the treated water discharged from the first container 34 is supplied to the second container 36, and an aqueous caustic soda solution is added to the second container 36 to adjust the pH in the second container 36 to 4. 0, and a circulating flow of 1 to 1.5 m / sec is formed inside by a stirrer 37 installed in the second container 36 and contained in the treated water from the first container 34. The pentavalent arsenic ions and trivalent iron ions deposited as metal compounds of iron and arsenic. Further, trivalent iron ions and pentavalent arsenic ions are deposited as metal compounds on the surface of the deposited iron and arsenic metal compound, and the iron and arsenic metal compound is deposited between the particles. The diameter was increased. The surplus liquid in the second container 36 was solid-liquid separated by the membrane module 39, and the treated water was sucked by the pump 40 and supplied to the next third container 41. The treated water contains divalent iron ions, copper ions, and zinc ions that did not precipitate in the second container. The pH of the treated water was 4.0. On the other hand, a part of the slurry in the second container 36 was pulled out and dehydrated with a dehydrator having a pressure of 0.098 MPa.

  Next, the treated water discharged from the second container 36 is supplied to the third container 41, and an aqueous caustic soda solution is added to the third container 41 to adjust the pH in the third container 41 to 4. 0.03, and further, air is blown at 0.5 NL / min from the blowing hole 43a of the compressed gas header 43 installed at the bottom of the third container 41 to stir the third container 41. It was. The divalent iron ions contained in the treated water from the second container 36 are oxidized into trivalent iron ions by the iron-oxidizing bacteria previously put in the third container 41, and iron hydroxide (III ). Furthermore, trivalent iron ions are precipitated as iron hydroxide (III) on the surface of the precipitated iron hydroxide (III) particles, and iron hydroxide (III) is precipitated between the particles. Was enlarged. The surplus liquid in the third container 41 was separated into solid and liquid by the membrane module 44, and the treated water was sucked by the pump 45 and supplied to the next fourth container 46. The treated water contains copper ions and zinc ions that did not precipitate in the third container. The pH of the treated water was 4.0. On the other hand, a part of the slurry in the third container 41 was pulled out and dehydrated with a dehydrator having a pressure of 0.098 MPa.

  Next, the treated water discharged from the third container 41 is supplied to the fourth container 46, and an aqueous caustic soda solution is added to the fourth container 46 to adjust the pH in the fourth container 46 to 8. .5 is neutralized, and air is blown at a rate of 0.5 NL / min from the blowing hole 48a of the compressed gas header 48 installed at the bottom of the fourth container 46 to stir the fourth container 46. It was. Copper ions and zinc ions contained in the treated water from the third container 41 were precipitated as metal hydroxide. Furthermore, the copper and zinc ions were precipitated as metal hydroxide on the surface of the precipitated metal hydroxide particles, and the metal hydroxide was precipitated between the particles, thereby increasing the particle diameter. The surplus liquid in the fourth container 46 was separated into solid and liquid by the membrane module 49, and the treated water was sucked by the pump 50 and discharged. The pH of the treated water was 8.5. On the other hand, a part of the slurry in the fourth container 46 was drawn and dehydrated with a dehydrator having a pressure of 0.098 MPa.

  The treated water quality from the first container 34, the treated water quality from the second container 36, the treated water quality from the third container 41 and the treated water quality from the fourth container 46 at this time are shown in Table 1, Table 2 shows the particle diameters in the container 36, the third container 41, and the fourth container 46, and the components of the dewatered sludge after dewatering.

( Reference Example 2)
The sludge containing iron, arsenic, copper and zinc ions shown in Table 3 is used as the target sludge, and the divalent iron ions, trivalent iron ions and pentavalent arsenic shown in Table 4 are used as the metal mine drainage. Using a solution containing ions, copper ions and zinc ions, the metal mine drainage and sludge were treated using the treatment apparatus of FIG. The capacities of the fifth container, the first container, the second container, the third container, and the fourth container are 1L, 0.6L, 1L, 3L, and 3L, respectively.

  50 g of sludge and 580 mL of metal mine drainage shown in Table 4 are charged into the fifth container 13, while stirring with a stirrer, sulfuric acid is charged into the fifth container 13, and the pH in the fifth container 13 is set to 2 .5. Into this, 2 g of iron powder was added, and trivalent iron ions were reduced to divalent iron ions. Then, at the stirring time of 2 hours, as shown in the treated water from the fifth container in Table 4, almost no trivalent iron ions are present, and only divalent iron ions are present. Arsenic / copper / zinc is in an ionic state and turns into a solution.

  Next, the treated water from the fifth container 13 is charged into the stock solution tank 33 at 0.4 mL / min, and the metal mine drainage 31 shown in Table 4 is charged into the stock solution tank 33 at 3.6 mL / min. Here, air was blown into the treated water in the stock solution tank 33 to control the dissolved oxygen concentration in the treated water to 4 mg / L, which was continuously supplied to the first container 34 at 4 mL / min. A stone having a diameter of 3 to 10 mm is installed in the first container 34 to immobilize iron-oxidizing bacteria. This iron-oxidizing bacterium oxidizes divalent iron ions to trivalent utilizing dissolved oxygen in the treated water, but only some of the divalent iron ions are oxidized by the dissolved oxygen rate limiting.

  Next, the treated water discharged from the first container 34 is supplied to the second container 36, and an aqueous caustic soda solution is added to the second container 36 to adjust the pH in the second container 36 to 4. 0, and a circulating flow of 1 to 1.5 m / sec is formed inside by a stirrer 37 installed in the second container 36 and contained in the treated water from the first container 34. The pentavalent arsenic ions and trivalent iron ions deposited as metal compounds of iron and arsenic. Further, trivalent iron ions and pentavalent arsenic ions are deposited as metal compounds on the surface of the deposited iron and arsenic metal compound, and the iron and arsenic metal compound is deposited between the particles. The diameter was increased. The surplus liquid in the second container 36 was solid-liquid separated by the membrane module 39, and the treated water was sucked by the pump 40 and supplied to the next third container 41. The treated water contains divalent iron ions, copper ions, and zinc ions that did not precipitate in the second container. The pH of the treated water was 4.0. On the other hand, a part of the slurry in the second container 36 was pulled out and dehydrated with a dehydrator having a pressure of 0.098 MPa.

  Next, the treated water discharged from the second container 36 is supplied to the third container 41, and an aqueous caustic soda solution is added to the third container 41 to adjust the pH in the third container 41 to 4. 0.03, and further, air is blown at 0.5 NL / min from the blowing hole 43a of the compressed gas header 43 installed at the bottom of the third container 41 to stir the third container 41. It was. The divalent iron ions contained in the treated water from the second container 36 are oxidized into trivalent iron ions by the iron-oxidizing bacteria previously put in the third container 41, and iron hydroxide (III ). Furthermore, trivalent iron ions are precipitated as iron hydroxide (III) on the surface of the precipitated iron hydroxide (III) particles, and iron hydroxide (III) is precipitated between the particles. Was enlarged. The surplus liquid in the third container 41 was separated into solid and liquid by the membrane module 44, and the treated water was sucked by the pump 45 and supplied to the next fourth container 46. The treated water contains copper ions and zinc ions that did not precipitate in the third container. On the other hand, a part of the slurry in the third container 41 was pulled out and dehydrated with a dehydrator having a pressure of 0.098 MPa.

  Next, the treated water discharged from the third container 41 is supplied to the fourth container 46, and an aqueous caustic soda solution is added to the fourth container 46 to adjust the pH in the fourth container 46 to 8. .5 is neutralized, and air is blown at a rate of 0.5 NL / min from the blowing hole 48a of the compressed gas header 48 installed at the bottom of the fourth container 46 to stir the fourth container 46. It was. Copper ions and zinc ions contained in the treated water from the third container 41 were precipitated as metal hydroxide. Furthermore, the particle diameter was increased by depositing copper ions and zinc ions as metal hydroxides on the precipitated metal hydroxide particle surfaces, or by depositing metal hydroxides between the particles. The surplus liquid in the fourth container 46 was solid-liquid separated by the membrane module 49, and the treated water was sucked by the pump 50 and discharged. On the other hand, a part of the slurry in the fourth container 46 was drawn and dehydrated with a dehydrator having a pressure of 0.098 MPa.

  At this time, the treated water quality from the fifth container 13, the treated water quality from the first container 34, the treated water quality from the second container 36, the treated water quality from the third container 41, and the fourth container 46 Table 4 shows the treated water quality, and Table 5 shows the particle size and the dehydrated sludge components in the second container 36, the third container 41, and the fourth container 46 after dehydration.

  Although it is an indoor experiment level as described above, it is an experiment correlated with actual wastewater, and this experimental result is a desirable result for recycling of dewatered sludge and is considered to be no different from actual wastewater.

The relationship between the pH of metal mine drainage that contains a part of divalent iron ions to trivalent iron ions and contains pentavalent arsenic ions, copper ions, and zinc ions and the residual ratio of elements in the metal mine drainage FIG. Diagram showing the relationship between the dissolution rate of heavy metals and the amount of iron powder input when trivalent iron ions in sludge containing arsenic, copper, zinc and iron generated during metal mine drainage treatment are reduced with metal iron powder It is. The graph which shows the relationship between the bivalent iron ion mass concentration in the filtered water filtered from the 3rd container, and the average particle diameter in the 3rd container in a steady state. The graph which shows the influence of the copper and zinc which precipitate in the 3rd container with respect to the average diameter of the particle | grains which consist of iron hydroxide (III). An example of the processing apparatus of the metal mine drainage which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Metal mine drainage processing and valuable metal recovery device 11 ... Sludge storage tank 12 ... Cutting pump 13 ... Fifth container 14 ... Diluent or acidic water 15 ... pH meter 16 ... ORP meter 17 ... Stirrer 18 ... Mineral acid DESCRIPTION OF SYMBOLS 19 ... Pump 20 ... Reducing agent storage 21 ... Cutting pump 22 ... Pump 23 ... Solid-liquid separator 31 ... Mine drainage 32 ... Dissolved oxygen concentration meter 33 ... Stock solution tank 34 ... First container 35 ... Stone 36 ... Second container 37 ... Stirrer 38 ... Rectification wall 39 ... Membrane separation device 40 ... Suction pump 41 ... Third vessel 42 ... Rectification wall 43 ... Aeration tube 44 ... Membrane separation device 45 ... Suction pump 46 ... Fourth vessel 47 ... Rectification wall 48 ... Aeration tube 49 ... Membrane separation device 50 ... Suction pump

Claims (15)

A method for treating mine drainage containing divalent iron ions and / or trivalent iron ions as acidic heavy metals generated from a metal mine , and containing arsenic ions ,
In the metal mine drainage, when the trivalent iron ion concentration is more than 1 time in terms of molar concentration with respect to the pentavalent arsenic ion concentration, the metal mine drainage is put into a second container, or In the metal mine drainage, when the trivalent iron ion concentration is less than 1 time in terms of molar concentration with respect to the pentavalent arsenic ion concentration, a compound composed of the metal mine drainage and trivalent iron ions is added. The trivalent iron ion concentration is adjusted to 1 to 3 times in terms of molar concentration with respect to the pentavalent arsenic ion concentration by introducing it into the stock solution tank. Put it in a container,
In the second container, the pH of the waste water is controlled to 3 to 5 to precipitate a compound of arsenic and trivalent iron ions, and then the precipitate is subjected to a solid-liquid separation process. Into a third container,
In the third container, the pH of the waste water is controlled to 6 to 10, air is blown, and divalent iron ions are oxidized to trivalent iron ions and at the same time iron hydroxide is precipitated. A method for treating metal mine drainage, characterized by sequentially performing a solid-liquid separation process and discharging a liquid component. It is a method for treating mine drainage that contains divalent iron ions and / or trivalent iron ions as acidic and heavy metals generated from a metal mine, contains arsenic ions, and further contains copper ions and / or zinc ions. And
In the metal mine drainage, when the trivalent iron ion concentration is more than 1 time in terms of molar concentration with respect to the pentavalent arsenic ion concentration, the metal mine drainage is put into a second container, When the trivalent iron ion concentration is less than 1 time in terms of molar concentration in the metal mine drainage with respect to the pentavalent arsenic ion concentration, the stock solution of the compound comprising the metal mine drainage and the trivalent iron ion is used. Put in the tank and adjust the trivalent iron ion concentration to 1 to 3 times in terms of molar concentration with respect to the pentavalent arsenic ion concentration. To
In the second container, the pH of the waste water is controlled to 3 to 5 to precipitate a compound of arsenic and trivalent iron ions, and then the precipitate is subjected to a solid-liquid separation process. Into a third container,
In the third container, the pH of the waste water is controlled to 3-5, iron-oxidizing bacteria are added, air is blown in, and bivalent iron ions are oxidized to trivalent iron ions, while iron hydroxide is deposited. Then, the precipitate is subjected to a solid-liquid separation process, and the liquid is put into a fourth container, and
Fourth in a vessel, to control the pH of the drainage 6-10, sequential processing method of the metal mining effluent and performing be precipitated copper and / or zinc as a metal hydroxide. The third container with respect to the mass concentration of iron in the waste water discharged from the second container having a divalent iron ion mass concentration of 150 mg / L or less in the waste water discharged from the third container The method according to claim 1 or 2 , wherein the ratio of the divalent iron ion mass concentration in the waste water discharged from the inside is 0.12 or less. The third container with respect to the mass concentration of iron in the waste water discharged from the second container having a divalent iron ion mass concentration of 20 mg / L or less in the waste water discharged from the third container The method according to claim 3 , wherein the ratio of the divalent iron ion mass concentration in the waste water discharged from the inside is 0.02 or less. Wherein the ratio of the total weight of zinc and copper ions are precipitated in the third vessel to the mass of the iron ions to be deposited in the third vessel is 0.1 or less, according to claim 2 the method of. Wherein the ratio of the total mass of the third third with respect to the mass of the iron ion to be deposited in a vessel of the container zinc and copper ions precipitate in is 0.01 or less, according to claim 5 the method of. In at least one tank among the second to fourth containers, the waste water is stirred, and metal ions are brought into contact with the deposited metal compound particles to increase the particle size, thereby dehydrating the metal compound having an increased particle size. The method according to any one of claims 1 to 6 , characterized in that: The method according to any one of claims 1 to 7 , wherein waste water in the container is filtered using a separation membrane in at least one tank among the second to fourth containers. The method according to claim 8 , wherein the pore size of the separation membrane is 1 to 100 μm. A neutralized precipitate generated when neutralizing acidic wastewater from a metal mine and water or acidic water are mixed in a fifth container to form a slurry, and the pH of the slurry is set to 1 or more and 5 or less. Control, put a reducing agent into the vessel, reduce trivalent iron ions to divalent iron ions, perform solid-liquid separation, put the liquid into the first vessel, and generate from the above metal mine to include bivalent iron ions and / or trivalent iron ions as heavy metal in acidic and arsenic ions are mixed in the mine effluent I containing trivalent part of divalent iron ions of the exhaust water After the treatment to oxidize to iron ions, the waste water is put into a second container, and the pH of the waste water is controlled to 3 to 5 in the second container, so that arsenic and trivalent iron ions are After precipitating the compound, the solid was subjected to solid-liquid separation, and the liquid was put into a third container. In the third container, the pH of the waste water is controlled to 6 to 10, air is blown, and divalent iron ions are oxidized to trivalent iron ions and iron hydroxide is precipitated at the same time. A method for treating metal mine drainage, comprising performing a solid-liquid separation process and discharging a liquid component sequentially . A neutralized precipitate generated when neutralizing acidic wastewater from a metal mine and water or acidic water are mixed in a fifth container to form a slurry, and the pH of the slurry is set to 1 or more and 5 or less. Control, put a reducing agent into the vessel, reduce trivalent iron ions to divalent iron ions, perform solid-liquid separation, put the liquid into the first vessel, and generate from the above metal mine It comprises bivalent iron ions and / or trivalent iron ions as heavy metal in acidic to, and includes arsenic ions, furthermore, mixed mine drainage containing copper ions and / or zinc ion, exhaust water After performing the process which oxidizes some of the divalent iron ions to trivalent iron ions, the waste water is put into the second container, and the pH of the waste water is adjusted to 3 to 5 in the second container. And depositing a compound of arsenic and trivalent iron ions, Liquid separation is performed, and the liquid is put into a third container. The pH of the waste water is controlled to 3 to 5 in the third container, iron-oxidizing bacteria are added, air is blown in, and bivalent The iron ion is oxidized to trivalent iron ions and iron hydroxide is precipitated at the same time, and then the precipitate is subjected to solid-liquid separation, and the liquid is put into a fourth container. And controlling the pH of the waste water to 6 to 10 and sequentially depositing at least one element of copper and zinc as a metal hydroxide . The method according to claim 10 or 11 , wherein at least one of dust generated from a refining furnace in the steel industry, a scale generated when rolling in the steel industry, and cutting waste is used as a reducing agent. The method according to claim 12 , wherein the specific surface area of metallic iron used as the reducing agent is 10 cm ² / g or more. The method according to any one of claims 10 to 13 , wherein metal mine drainage is used as the acidic water to be put into the fifth container. A method for recovering valuable metals in metal mine drainage, wherein the metal hydroxide precipitated by the method according to any one of claims 1 to 14 is recovered as sludge.

Images