Method for treating acid mine wastewater containing iron ions

Abstract

The invention relates to the technical field of mine waste liquid treatment, in particular to a method for treating acid mine waste water containing iron ions. The method comprises the following steps: carrying out reduction reaction on acid mine wastewater containing iron ions by using an iron-containing reducing agent to obtain a mixture; carrying out solid-liquid separation on the mixture to obtain a ferrous ion solution; performing membrane treatment on the ferrous ion solution to obtain a concentrated solution; and carrying out crystallization reaction on an alcohol solventing-out agent, a ferrite seed crystal and the concentrated solution to obtain crystal slurry containing ferrite crystals. According to the method, reduction reaction, solid-liquid separation, membrane treatment and crystallization reaction are combined, so that the purity of an iron product obtained by treating the acid mine wastewater containing iron ions can be synchronously improved to 95% or above, and the recovery rate can be synchronously improved to 94% or above.

Description

Technical Field

[0001] The present application relates to the technical field of mine wastewater treatment, and in particular to a method for treating acid mine wastewater containing iron ions. Background Art

[0002] During copper mining and tailings storage, various metal ions such as iron and copper in the ore and tailings mined from copper mines will dissolve from the ore or tailings under the combined action of air, water and microorganisms to form acidic mine wastewater containing sulfuric acid and metal sulfates. These acidic mine wastewaters have high content of iron and sulfate ions, which will cause acidic mine wastewater to seriously damage the surrounding soil, rivers and even downstream farmland and other ecological environments, and may even endanger human health through the food chain.

[0003] At present, the treatment methods for acidic mine wastewater containing iron ions include chemical precipitation, ion exchange, electrolysis, membrane separation, etc., but these methods are difficult to effectively recover iron ions and prepare high-purity iron products.

[0004] The current methods for treating acid mine drainage include: (1) chemical precipitation, which has the advantages of mature technology and good economy; (2) ion exchange, which has a high metal ion recovery rate; (3) electrolysis, which precipitates metal products on the electrode surface by electrolysis and has a high metal product recovery rate; (4) membrane separation, which can effectively recover water and the recovered water can be recycled and has the characteristics of high efficiency. Summary of the invention

[0005] The present application provides a method for treating acidic mine wastewater containing iron ions to solve the following technical problem: how to simultaneously improve the purity and recovery rate of the iron product obtained by treating acidic mine wastewater containing iron ions.

[0006] In a first aspect, the present application provides a method for treating acid mine wastewater containing iron ions, the method comprising:

[0007] Using an iron-containing reducing agent, subjecting the acid mine wastewater containing iron ions to a reduction reaction so that the iron ions are reduced to ferrous ions, thereby obtaining a mixture;

[0008] The mixture is subjected to solid-liquid separation to obtain a ferrous ion solution;

[0009] subjecting the ferrous ion solution to membrane treatment to obtain a concentrated solution; and

[0010] The alcohol solvent, the ferrous salt seed crystals and the concentrated solution are subjected to a crystallization reaction to obtain a crystal slurry containing ferrous salt crystals.

[0011] Optionally, the added volume V1 of the alcohol solvent and the volume V2 of the concentrated solution satisfy the relationship: V1:V2=(0.2-1.0):1; and / or

[0012] The weight m1 of the ferrous salt seed crystals and the volume V2 of the concentrated solution satisfy the relationship: m1:V2=(0-20):1, wherein if the unit of V2 is L, the unit of m1 is g.

[0013] Optionally, the alcohol solvent includes at least one of the following: methanol, anhydrous ethanol and n-propanol.

[0014] Optionally, the temperature of the crystallization reaction is 5°C to 15°C, and the time of the crystallization reaction is 30min to 75min.

[0015] Optionally, the weight m2 of the iron-containing reducing agent and the volume V3 of the acid mine drainage water satisfy the relationship: m2:V3≥5:1, wherein, if the unit of V3 is L, the unit of m2 is g.

[0016] Optionally, the reduction reaction time is ≥ 20 min.

[0017] Optionally, the mass concentration of ferrous ions in the concentrated solution is ≥30 g / L.

[0018] Optionally, the alcohol solvent, the ferrous salt seed crystals and the concentrated solution are subjected to a crystallization reaction to obtain a crystal slurry containing ferrous salt crystals, and then the process further comprises:

[0019] The crystal slurry containing the ferrous salt crystals is subjected to solid-liquid separation to obtain a precipitated crystal and a supernatant respectively;

[0020] Drying the precipitated crystals to obtain a ferrous salt product;

[0021] The supernatant is distilled to obtain an alcohol solvent.

[0022] Optionally, the drying treatment includes vacuum drying treatment, the temperature of the vacuum drying treatment is ≤50°C, and the time of the vacuum drying treatment is 240min to 480min.

[0023] Optionally, the solid-liquid separation of the mixture to obtain a ferrous ion solution comprises:

[0024] The mixture is subjected to solid-liquid separation to obtain a ferrous ion solution and a metal impurity element;

[0025] The mixture is subjected to solid-liquid separation to obtain a ferrous ion solution and a metal impurity element, and then further comprises:

[0026] The metal impurity single substance is separated by ultrasonic and magnetic separation to obtain a magnetic metal product and a non-magnetic metal product respectively; wherein the magnetic metal product is used as an iron-containing reducing agent.

[0027] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0028] The embodiment of the present application provides a method for treating acid mine wastewater containing iron ions. The method reduces the iron ions in the acid mine wastewater into ferrous ions by using an iron-containing reducing agent, and then obtains a ferrous ion solution with a higher purity by solid-liquid separation. The ferrous ion solution can not only remove impurities of the ferrous ion solution by membrane treatment, but also concentrate the ferrous ion solution into a concentrated solution containing high concentration of ferrous ions by the interception effect of the membrane treatment. In addition, based on the characteristics of alcohol solvents that reduce the solubility of ferrous ions and control the degree of crystallization and the induced crystallization of ferrous salt seeds, the ferrous ion solution can be concentrated to a high concentration of ferrous ions. An alcohol solvent and ferrous salt seeds are added to a concentrated solution containing concentrated ferrous ions. Under the combined action of the two, most of the ferrous ions in the concentrated solution will quickly precipitate and crystallize and leave the liquid phase of the concentrated solution, while other impure metal ions will still remain in the liquid phase of the concentrated solution, thereby effectively removing the impure metal ions and improving the recovery rate of ferrous ions to obtain a crystal slurry containing high-purity ferrous salt crystals. Therefore, this method can simultaneously improve the purity and recovery rate of iron products obtained by treating acidic mine wastewater containing iron ions by combining reduction reaction, solid-liquid separation, membrane treatment and crystallization reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0031] Figure 1 A schematic flow chart of a core method for treating acid mine wastewater containing iron ions provided in an embodiment of the present application;

[0032] Figure 2 A schematic flow chart of a method for treating acidic mine wastewater containing iron ions provided in an embodiment of the present application;

[0033] Figure 3 A detailed schematic diagram of a method for treating acidic mine wastewater containing iron ions provided in an embodiment of the present application;

[0034] Figure 4 A schematic diagram of an actual process of a method for treating acidic mine wastewater containing iron ions provided in an embodiment of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0036] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range; in addition, whenever a numerical range is indicated in this document, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0037] In this document, the terms including "including" and "including" mean "including but not limited to". Relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone; where A and B can be singular or plural. "At least one" means one or more, and "plurality" means two or more; "at least one", "at least one of the following" or similar expressions, refers to any combination of these items, including any combination of single or plural items; for example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. "Parts" such as parts by weight and parts by mass indicate the proportional relationship between the components. In the proportional relationship involved in this article, the parameters that need to be described by proportion should be understood as the first term of the proportional formula in the order of description, and the proportional numbers should be understood as the second term of the proportional formula. For example, if the mass ratio of substance A, substance B and substance C is 1:2:3, then substance A, substance B and substance C should correspond to the proportional numbers in the proportional formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0038] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this article can be purchased from the market or prepared by existing methods.

[0039] It should be noted that, with respect to the prior art (1) in the background technology, the inventors found that the chemical precipitation method has a large slag production, a high sludge moisture content, is difficult to filter, and has a high iron content in the sludge, making it difficult to obtain a high-purity iron product; with respect to the prior art (2) in the background technology, the inventors found that the ion exchange method is expensive, and the ion exchange resin used in the ion exchange method requires frequent regeneration, which makes the operation steps more complicated. In addition, there will be a loss of iron ions, which affects the recovery rate of the iron product; with respect to the prior art (3) in the background technology, the inventors found that the electrolysis method consumes a lot of electricity and has a small amount of wastewater to treat. In addition, the subsequent separation of iron ions requires more complicated post-treatment steps, and there will be a loss of iron ions, which affects the recovery rate of the iron product; with respect to the prior art (4) in the background technology, the inventors found that the metal ions in the membrane separation method will be concentrated in the same liquid phase, requiring subsequent complex operations to separate the iron product, which causes the loss of iron ions in the subsequent operation steps, thereby affecting the recovery rate of the iron product.

[0040] Therefore, how to simultaneously improve the purity and recovery rate of the iron product obtained by the method for treating acidic mine wastewater containing iron ions is a technical problem that urgently needs to be solved.

[0041] Figure 1 A schematic flow chart of a core method for treating acid mine wastewater containing iron ions provided in an embodiment of the present application is exemplarily shown;

[0042] Figure 4 The actual process diagram of a method for treating acid mine wastewater containing iron ions provided in an embodiment of the present application is exemplarily shown;

[0043] like Figure 1 and Figure 4 As shown, the embodiment of the present application provides a method for treating acid mine wastewater containing iron ions, the method comprising:

[0044] S1. using an iron-containing reducing agent, subjecting the acidic mine wastewater containing iron ions to a reduction reaction so that the iron ions are reduced to ferrous ions to obtain a mixture;

[0045] S2. The mixture is subjected to solid-liquid separation to obtain a ferrous ion solution;

[0046] S3. The ferrous ion solution is subjected to membrane treatment to obtain a concentrated solution; and

[0047] S4. subjecting the alcohol solvent, the ferrous salt seed crystals and the concentrated solution to a crystal slurry containing ferrous salt crystals.

[0048] It should be noted that the membrane treatment can be carried out using ultrafiltration membrane, nanofiltration membrane or reverse osmosis membrane, or a comprehensive treatment can be carried out using ultrafiltration membrane, nanofiltration membrane and reverse osmosis membrane; in addition, these ultrafiltration membrane, nanofiltration membrane and reverse osmosis membrane use acid-resistant and pollution-resistant membrane materials.

[0049] It should be noted that in addition to obtaining a concentrated liquid, the membrane treatment can also obtain a purified liquid, which can be returned to the subsequent production process for use, or directly added with an acid-base regulator to adjust the pH to 7-9 and then neutralized to meet the emission standards; the acid-base regulator can be quicklime, slaked lime, calcium carbonate, sodium carbonate, or sodium hydroxide; in addition, the neutralization treatment time can be ≥30 minutes.

[0050] It should be noted that if the acid mine wastewater comes from a copper mine, the acid mine wastewater may also contain copper ions. During the reduction reaction, the copper ions can be reduced to copper element. In the subsequent solid-liquid separation process, the copper element will be separated from the ferrous ion solution to obtain a crude copper product.

[0051] It should be noted that the iron-containing reducing agent can be iron powder, iron filings, or iron sheets.

[0052] In some optional embodiments, the added volume V1 of the alcohol solvent and the volume V2 of the concentrated solution satisfy the relationship: V1:V2=(0.2-1.0):1; and / or

[0053] The weight m1 of the ferrous salt seed crystal and the volume V2 of the concentrated solution satisfy the relationship: m1:V2=(0-20):1, wherein if the unit of V2 is L, the unit of m1 is g;

[0054] In these embodiments, the added volume V1 of the alcohol solvent and the volume V2 of the concentrated solution can satisfy the relationship: V1:V2=(0.2-1.0):1, which enables the concentrated solution to have a sufficient amount of alcohol solvent. A sufficient amount of alcohol solvent can reduce the solubility of ferrous ions in the concentrated solution, so as to facilitate the precipitation of a sufficient amount of ferrous salt crystals under the induced crystallization of the ferrous salt seed. In addition, the alcohol solvent will not affect the solubility of impurity metal ions, and can improve the purity of the precipitated ferrous salt crystals. In addition, a sufficient amount of alcohol solvent can also promote the concentrated solution. A supersaturated solution is formed to allow ferrous ions to quickly form and grow into nuclei of ferrous salt crystals, thereby improving the crystallization efficiency of ferrous salt crystals; in addition, the weight m1 of the ferrous salt seed crystals and the volume V2 of the concentrated solution can satisfy the relationship: m1:V2=(0-20):1, wherein, if the unit of V2 is L, the unit of m1 is g, which enables the concentrated solution to have sufficient ferrous salt seed crystals. Sufficient ferrous salt seed crystals can induce the ferrous ions in the concentrated solution to quickly form and grow into nuclei of ferrous salt crystals, thereby obtaining a large number of ferrous salt crystals.

[0055] The added volume V1 of the alcohol solvent can be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1.0.

[0056] The weight m1 of the ferrous salt seed can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

[0057] In some optional embodiments, the alcohol solvent includes at least one of the following: methanol, anhydrous ethanol and n-propanol;

[0058] In these embodiments, the alcohol solvent may include: at least one of methanol, anhydrous ethanol and n-propanol, which may include most of the alcohol solvents. The alcohol solvent may reduce the solubility of ferrous ions in the concentrate without affecting the solubility of impurity metal ions, so as to facilitate the precipitation of sufficient and high-purity ferrous salt crystals under the induced crystallization of ferrous salt seeds.

[0059] In some optional embodiments, the temperature of the crystallization reaction is 5°C to 15°C, and the time of the crystallization reaction is 30min to 75min;

[0060] In these embodiments, the temperature of the crystallization reaction can be 5°C to 15°C, and the time of the crystallization reaction can be 30min to 75min, so that the crystallization reaction has a sufficiently high temperature and a sufficiently long time, so that the ferrous ions in the concentrated solution precipitate sufficient and high-purity ferrous salt crystals under the action of the alcohol solvent and the ferrous salt seeds.

[0061] The temperature of the crystallization reaction can be 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 11°C, 12°C, 13°C, 14°C or 15°C.

[0062] The crystallization reaction time can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min or 75 min.

[0063] In some optional embodiments, the weight m2 of the iron-containing reducing agent and the weight V3 of the acid mine drainage water satisfy the relationship: m2:V3≥5:1, wherein if the unit of V3 is L, the unit of m2 is g;

[0064] In these methods, the weight m2 of the iron-containing reducing agent and the weight V3 of the acid mine drainage water can satisfy the relationship: m2:V3≥5:1, so that the acid mine drainage water has a sufficient amount of iron-containing reducing agent. The sufficient amount of iron-containing reducing agent can be fully reduced to ferrous ions and impurity metal elements with the iron ions and part of the impurity metal ions in the acid mine drainage water, thereby obtaining a mixture containing a large amount of ferrous ions.

[0065] In some optional embodiments, the reduction reaction time is ≥ 20 min;

[0066] In these methods, the reduction reaction time can be ≥20 minutes, which ensures that the reduction reaction has a sufficiently long time. The reduction reaction for a sufficiently long time can enable the iron-containing reducing agent to fully react with the iron ions in the acidic mine wastewater and some impurity metal ions to be reduced to ferrous ions and impurity metal elements, thereby obtaining a mixture containing a large amount of ferrous ions.

[0067] In some optional embodiments, the mass concentration of ferrous ions in the concentrated solution is ≥30 g / L;

[0068] In these methods, the mass concentration of ferrous ions in the concentrate can be ≥30g / L, so that the concentrate has a large amount of ferrous ions, so as to promote the concentrate to precipitate sufficient and high-purity ferrous salt crystals under the action of alcohol solvent and ferrous salt seeds.

[0069] Figure 2 A schematic flow chart of a method for treating acid mine wastewater containing iron ions provided in an embodiment of the present application is exemplarily shown;

[0070] In some optional embodiments, such as Figure 2 As shown, the alcohol solvent, the ferrous salt seed crystals and the concentrated solution are subjected to a crystallization reaction to obtain a crystal slurry containing ferrous salt crystals, and then the process further comprises:

[0071] S5. The crystal slurry containing the ferrous salt crystals is subjected to solid-liquid separation to obtain a precipitated crystal and a supernatant, respectively;

[0072] S6. Drying the precipitated crystals to obtain a ferrous salt product;

[0073] S7. distilling the supernatant to obtain an alcohol solvent.

[0074] In these methods, the solid-liquid separation is performed on the crystal slurry containing ferrous salt crystals, so that the solid phase and liquid phase of the ferrous salt crystals can be separated, and the precipitated crystals obtained by the solid-liquid separation are then dried to fully remove the liquid phase of the ferrous salt crystals, thereby obtaining a high-purity ferrous salt product; in addition, the supernatant is distilled to separate the acid component and the alcohol solvent of the supernatant, and the obtained acid can be reused as a leachate in the mine, and the obtained alcohol solvent can be reused in the crystallization reaction.

[0075] It should be noted that the distillation treatment may use a single distillation system or a multiple distillation system.

[0076] In some optional embodiments, the drying treatment includes vacuum drying treatment, the temperature of the vacuum drying treatment is ≤50°C, and the time of the vacuum drying treatment is 240min to 480min.

[0077] Among these methods, the drying treatment may include vacuum drying treatment, and the temperature of the vacuum drying treatment may be ≤50°C, and the time of the vacuum drying treatment may be 240min to 480min, so that the vacuum drying treatment is fully carried out to fully remove the moisture of the precipitated crystals under the condition of isolating oxygen, thereby obtaining a high-purity ferrous salt product.

[0078] The vacuum drying treatment time can be 240 min, 300 min, 360 min, 420 min or 480 min.

[0079] Figure 3 A detailed schematic diagram of a method for treating acid mine wastewater containing iron ions provided in an embodiment of the present application is exemplarily shown;

[0080] In some optional embodiments, such as Figure 3 As shown, the mixture is subjected to solid-liquid separation to obtain a ferrous ion solution, comprising:

[0081] S201. The mixture is subjected to solid-liquid separation to obtain a ferrous ion solution and a metal impurity element;

[0082] The mixture is subjected to solid-liquid separation to obtain a ferrous ion solution and a metal impurity element, and then further comprises:

[0083] S202. Separate the metal impurity element by ultrasonic and magnetic separation to obtain a magnetic metal product and a non-magnetic metal product, respectively; wherein the magnetic metal product is used as an iron-containing reducing agent.

[0084] In these methods, when the acid mine wastewater contains impurity metal ions (which may be copper) other than iron ions, during the reduction reaction, not only are the iron ions reduced to ferrous ions but also some of the impurity metal ions are reduced to impurity metal elements. The mixture containing the impurity metal element and the ferrous ion solution is then subjected to solid-liquid separation, which can effectively separate a large amount of ferrous ion solution with higher purity. In addition, the impurity metal element is subjected to ultrasonic and magnetic separation, which can fully separate the magnetic metal and non-magnetic metal of the impurity metal element, and a pure magnetic metal can be obtained. Based on the characteristic that the magnetic metal contains a large amount of iron elements, the obtained magnetic metal can be used as an iron-containing reducing agent.

[0085] In summary, the method for treating acidic mine wastewater containing iron ions provided in the embodiment of the present application also has the following advantages:

[0086] 1. It has an efficient treatment process: the core steps of the method include reduction reaction, solid-liquid separation, membrane treatment and crystallization reaction, and these steps are interconnected. The iron ions and some impurity metal ions in the acid mine wastewater are reduced to ferrous ions and impurity metal elements through the reduction reaction. This step not only reduces the harmful metal ion content of the acid mine wastewater, but also reduces the oxidizability of the acid mine wastewater; in addition, the ferrous ions can be effectively separated from the unreacted reducing agent, other solid impurities and some soluble impurities through the solid-liquid separation operation; in addition, the method can not only remove impurities such as suspended matter, colloids, and organic matter in the ferrous ion solution through the interception effect of the membrane treatment, but also increase the mass concentration of the ferrous ion solution to facilitate the subsequent crystallization reaction; in addition, the method precipitates the ferrous ions of the ferrous ion solution in the form of crystals through the crystallization reaction, while other impurity metal ions still remain in the liquid phase due to factors such as solubility and charge properties, thereby realizing the purification and efficient recovery of ferrous ions.

[0087] 2. Environmental protection and economic benefits: The whole process of this method only requires the addition of an iron source (containing an iron reducing agent and / or ferrous salt seeds) and an alcohol solvent, without the introduction of other impurity ions, thereby avoiding the subsequent removal of impurity ions, saving the treatment cost of acid mine wastewater and making the method more environmentally friendly.

[0088] The present application is further described below in conjunction with specific examples. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards / industry standards; if there are no corresponding national standards / industry standards, they are measured in accordance with common international standards, conventional conditions or conditions recommended by the manufacturer.

[0089] Example 1

[0090] The residual extraction solution obtained by extracting and recovering the copper product of a copper mine in a certain place is taken as acid mine wastewater, and 1L of the acid mine wastewater is placed in a stirring tank.

[0091] like Figure 3 and Figure 4 A method for treating acid mine drainage containing iron ions, comprising:

[0092] S1. Using 5g of an iron-containing reducing agent, the acidic mine wastewater containing iron ions is subjected to a reduction reaction so that the iron ions are reduced to ferrous ions and other metal impurity ions are reduced to metal impurity elements to obtain a mixture;

[0093] S201. The mixture is subjected to solid-liquid separation to obtain a ferrous ion solution and a metal impurity element;

[0094] S202. Separate the metal impurities by ultrasonic and magnetic separation to obtain magnetic metal products and non-magnetic metal products respectively; wherein the magnetic metal product is used as an iron-containing reducing agent.

[0095] S3. The ferrous ion solution is subjected to membrane treatment to obtain a concentrated solution and a purified solution;

[0096] S4. The alcohol solvent, the ferrous salt seed crystals and the concentrated solution are subjected to a crystallization reaction to obtain a crystal slurry containing ferrous salt crystals;

[0097] S5. The crystal slurry containing ferrous salt crystals is subjected to solid-liquid separation to obtain a precipitated crystal and a supernatant, respectively;

[0098] S6. Drying the precipitated crystals to obtain a ferrous salt product;

[0099] S7. The supernatant is distilled to obtain an alcohol solvent.

[0100] The iron-containing reducing agent is iron powder (iron content by weight ≥ 98%).

[0101] The purified liquid and the acid-base regulator are neutralized to obtain an effluent liquid; wherein the target pH of the neutralization treatment is 7, and the weight m3 of the acid-base regulator and the weight m4 of the purified liquid satisfy the relationship: m3:m4=10:100.

[0102] The added volume V1 of the alcohol solvent and the volume V2 of the concentrated solution satisfy the relationship: V1:V2=0.2:1;

[0103] The weight m1 of the ferrous salt seed crystals and the volume V2 of the concentrated liquid satisfy the relationship: m1:V2=20g:1L.

[0104] The alcohol solvent is anhydrous ethanol.

[0105] The temperature of the crystallization reaction was 15°C, and the time of the crystallization reaction was 30 min.

[0106] The weight m2 of the iron-containing reducing agent and the volume V3 of the acid mine drainage water satisfy the relationship: m2:V3=5g:1L.

[0107] The reduction reaction time is 30 min.

[0108] The mass concentration of ferrous ions in the concentrated solution is 33.12 g / L.

[0109] The drying process includes vacuum drying process, the temperature of the vacuum drying process is 45° C., and the time of the vacuum drying process is 480 min.

[0110] Example 2

[0111] Based on the contents disclosed in Example 1, the following modifications are further made:

[0112] The iron-containing reducing agent is iron powder (iron content by weight ≥ 98%).

[0113] The added volume V1 of the alcohol solvent and the volume V2 of the concentrated solution satisfy the relationship: V1:V2=0.4:1;

[0114] The weight m1 of the ferrous salt seed crystals and the volume V2 of the concentrated liquid satisfy the relationship: m1:V2=20g:1L.

[0115] The alcohol solvent is anhydrous ethanol.

[0116] The temperature of the crystallization reaction was 15°C, and the time of the crystallization reaction was 30 min.

[0117] The weight m2 of the iron-containing reducing agent and the volume V3 of the acid mine drainage water satisfy the relationship: m2:V3=7g:1L.

[0118] The reduction reaction time is 30 min.

[0119] The mass concentration of ferrous ions in the concentrated solution is 38.69 g / L.

[0120] The temperature of the vacuum drying treatment was 45°C, and the time of the vacuum drying treatment was 420 min.

[0121] Example 3

[0122] Based on the contents disclosed in Example 1, the following modifications are further made:

[0123] The iron-containing reducing agent is an iron flake (iron content by weight ≥ 98%).

[0124] The added volume V1 of the alcohol solvent and the volume V2 of the concentrated solution satisfy the relationship: V1:V2=0.8:1;

[0125] The weight m1 of the ferrous salt seed crystals and the volume V2 of the concentrated solution satisfy the relationship: m1:V2=15g:1L.

[0126] The temperature of the crystallization reaction was 10°C, and the time of the crystallization reaction was 60 min.

[0127] The weight m2 of the iron-containing reducing agent and the volume V3 of the acid mine drainage water satisfy the relationship: m2:V3=15g:1L.

[0128] The reduction reaction time is 30 min.

[0129] The mass concentration of ferrous ions in the concentrated solution is 65.82 g / L.

[0130] The temperature of the vacuum drying treatment was 45°C, and the time of the vacuum drying treatment was 360 min.

[0131] Example 4

[0132] Based on the contents disclosed in Example 1, the following modifications are further made:

[0133] The iron-containing reducing agent is an iron flake (iron content by weight ≥ 98%).

[0134] The added volume V1 of the alcohol solvent and the volume V2 of the concentrated solution satisfy the relationship: V1:V2=0.8:1;

[0135] The weight m1 of the ferrous salt seed crystals and the volume V2 of the concentrated liquid satisfy the relationship: m1:V2=10g:1L.

[0136] The temperature of the crystallization reaction was 10°C, and the time of the crystallization reaction was 60 min.

[0137] The weight m2 of the iron-containing reducing agent and the volume V3 of the acid mine drainage water satisfy the relationship: m2:V3=12g:1L.

[0138] The reduction reaction time is 30 min.

[0139] The mass concentration of ferrous ions in the concentrated solution is 61.87 g / L.

[0140] The temperature of the vacuum drying treatment was 45°C, and the time of the vacuum drying treatment was 360 min.

[0141] Example 5

[0142] Based on the contents disclosed in Example 1, the following modifications are further made:

[0143] The iron-containing reducing agent is iron filings (iron content by weight ≥ 95%).

[0144] The added volume V1 of the alcohol solvent and the volume V2 of the concentrated solution satisfy the relationship: V1:V2=1.0:1;

[0145] The weight m1 of the ferrous salt seed and the volume V2 of the concentrated solution satisfy the relationship: m1:V2=0g:1L.

[0146] The alcohol solvent is anhydrous ethanol.

[0147] The temperature of the crystallization reaction was 5°C, and the time of the crystallization reaction was 75 min.

[0148] The mass m2 of the iron-containing reducing agent and the volume V3 of the acid mine drainage water satisfy the relationship: m2:V3=10g:1L.

[0149] The reduction reaction time is 30 min.

[0150] The mass concentration of ferrous ions in the concentrated solution is 53.66 g / L.

[0151] The temperature of the vacuum drying treatment was 45° C., and the time of the vacuum drying treatment was 300 min.

[0152] Example 6

[0153] Based on the contents disclosed in Example 1, the following modifications are further made:

[0154] The iron-containing reducing agent is iron filings (iron content by weight ≥ 95%).

[0155] The added volume V1 of the alcohol solvent and the volume V2 of the concentrated solution satisfy the relationship: V1:V2=0.6:1;

[0156] The mass m1 of the ferrous salt seed and the volume V2 of the concentrated liquid satisfy the relationship: m1:V2=0g:1L.

[0157] The temperature of the crystallization reaction was 5°C, and the time of the crystallization reaction was 75 min.

[0158] The mass m2 of the iron-containing reducing agent and the volume V3 of the acid mine drainage water satisfy the relationship: m2:V3=10g:1L.

[0159] The reduction reaction time is 30 min.

[0160] The mass concentration of ferrous ions in the concentrated solution is 49.87 g / L.

[0161] The temperature of the vacuum drying treatment was 45°C, and the time of the vacuum drying treatment was 240 min.

[0162] Comparative Example 1

[0163] Based on the contents disclosed in Example 1, the following modifications are further made:

[0164] The weight m2 of the iron-containing reducing agent and the volume V3 of the acid mine drainage water satisfy the relationship: m2:V3=3g:1L.

[0165] Comparative Example 2

[0166] Based on the contents disclosed in Example 1, the following modifications are further made:

[0167] The reduction reaction time is less than 20 min, and the reduction reaction time is 10 min.

[0168] Comparative Example 3

[0169] Based on the contents disclosed in Example 1, the following modifications are further made:

[0170] No alcohol solvent is added.

[0171] Comparative Example 4

[0172] Based on the contents disclosed in Example 1, the following modifications are further made:

[0173] The added volume V1 of the alcohol solvent and the volume V2 of the concentrated solution satisfy the relationship: V1:V2=2.0:1.

[0174] Comparative Example 5

[0175] Based on the contents disclosed in Example 1, the following modifications are further made:

[0176] The weight m1 of the ferrous salt seed and the volume V2 of the concentrated solution satisfy the relationship: m1:V2=30g:1L.

[0177] Related experiments and effect data:

[0178] The samples of acid mine drainage used in each embodiment and comparative example and the products recovered were statistically analyzed, and the results are shown in Table 1 and Table 2.

[0179] Table 1: Samples used in various examples and comparative examples

[0180]

[0181] Table 2 The product status of each embodiment and comparative example

[0182]

[0183] It can be seen from Tables 1 and 2 that the embodiment of the present application provides a method for treating acidic mine wastewater containing iron ions. The method combines reduction reaction, solid-liquid separation, membrane treatment and crystallization reaction to simultaneously improve the purity of the iron product obtained by treating acidic mine wastewater containing iron ions to more than 95% and the recovery rate to 94% or more.

[0184] In addition, it was found during the research process that with the increase in the volume of alcohol solvent, the alcohol solvent had a limited improvement in the recovery rate and purity of the iron product. Although the recovery rate of ferrous sulfate in Comparative Example 4 in Table 1 can reach more than 94%, an excessive amount of alcohol solvent was added in Comparative Example 4 compared to the embodiment, but the recovery rate of ferrous sulfate and the purity of ferrous sulfate product were only increased by 0.2%, which was in line with the actual law found above. Therefore, for the consideration of actual production cost, the excessive addition of the alcohol solvent in Comparative Example 4 was not necessary. In addition, it was found during the research process that with the increase in the amount of seed added, the recovery rate of the iron product would show a trend of first increasing and then decreasing, but the influence of the amount of seed added on the recovery rate of the iron product fluctuated within 5%. Although the recovery rate of ferrous sulfate in Comparative Example 5 in Table 1 can reach 93.4%, its ferrous salt seeds were added in excess compared to Example 1, and the recovery rate of the iron product was also reduced by 1.8%, which was in line with the actual law found above. Therefore, the excessive addition of ferrous salt seeds in Comparative Example 5 was not necessary.

[0185] In addition, a method for treating acidic mine wastewater containing iron ions provided in an embodiment of the present application only requires the addition of an iron source and an alcohol solvent and the selective addition of ferrous salt seeds, which can avoid the introduction of impurity ions and thus reduce the treatment cost of acidic mine wastewater containing iron ions.

[0186] In addition, an embodiment of the present application provides a method for treating acidic mine wastewater containing iron ions. According to the characteristics of acidic mine wastewater with low pH, high iron content and high sulfate ion content, the method combines reduction reaction, solid-liquid separation, membrane treatment, crystallization reaction and distillation technology to obtain a high-purity and high-recovery ferrous sulfate product. In addition, part of the crude copper product can be recovered from the acidic mine wastewater containing copper ions and iron ions, and the industrialization value is high. In addition, the waste liquid discharged during the method can be recycled or directly meet the emission standards after neutralization treatment, which makes the method environmentally friendly.

[0187] In summary, the embodiment of the present application provides a method for treating acidic mine wastewater containing iron ions, which has the advantages of high treatment efficiency, simple process flow, easy industrial application, and environmental friendliness.

[0188] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. It will be apparent to those skilled in the art that various modifications to these embodiments are possible, and the general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown in the present application, but will conform to the widest range consistent with the principles and novel features applied for by the present application.

Claims

1. A method for treating acid mine wastewater containing iron ions, the method comprising: Using an iron-containing reducing agent, subjecting the acid mine wastewater containing iron ions to a reduction reaction so that the iron ions are reduced to ferrous ions, thereby obtaining a mixture; The mixture is subjected to solid-liquid separation to obtain a ferrous ion solution; The ferrous ion solution is subjected to membrane treatment to obtain a concentrated solution; as well as The alcohol solvent, the ferrous salt seed crystals and the concentrated solution are subjected to a crystallization reaction to obtain a crystal slurry containing ferrous salt crystals.

2. The method according to claim 1, wherein the added volume V1 of the alcohol solvent and the volume V2 of the concentrated solution satisfy the relationship: V1:V2=(0.2-1.0):1; and / or The weight m1 of the ferrous salt seed crystals and the volume V2 of the concentrated solution satisfy the relationship: m1:V2=(0-20):1, wherein, If the unit of V2 is L, the unit of m1 is g.

3. The method according to claim 1, wherein the alcohol solvent comprises at least one of the following: methanol, anhydrous ethanol and n-propanol.

4. The method according to claim 1, wherein the temperature of the crystallization reaction is 5°C to 15°C, and the time of the crystallization reaction is 30 min to 75 min.

5. The method according to claim 1, wherein the weight m2 of the iron-containing reducing agent and the volume V3 of the acid mine drainage water satisfy the relationship: m2:V3≥5:1, wherein, If the unit of V3 is L, the unit of m2 is g.

6. The method according to claim 1, wherein the reduction reaction time is ≥ 20 min.

7. The method according to claim 1, wherein the mass concentration of ferrous ions in the concentrated solution is ≥30 g / L.

8. The method according to claim 1, wherein the alcohol solvent, the ferrous salt seed crystals and the concentrated solution are subjected to a crystallization reaction to obtain a crystal slurry containing ferrous salt crystals, and then further comprising: The crystal slurry containing the ferrous salt crystals is subjected to solid-liquid separation to obtain a precipitated crystal and a supernatant respectively; Drying the precipitated crystals to obtain a ferrous salt product; The supernatant is distilled to obtain an alcohol solvent.

9. The method according to claim 8, wherein the drying process comprises a vacuum drying process, the temperature of the vacuum drying process is ≤50°C, and the time of the vacuum drying process is 240 min to 480 min.

10. The method according to claim 1, wherein the mixture is subjected to solid-liquid separation to obtain a ferrous ion solution, comprising: The mixture is subjected to solid-liquid separation to obtain a ferrous ion solution and a metal impurity element; The mixture is subjected to solid-liquid separation to obtain a ferrous ion solution and a metal impurity element, and then further comprises: The metal impurity single substance is separated by ultrasonic and magnetic separation to obtain a magnetic metal product and a non-magnetic metal product respectively; wherein the magnetic metal product is used as an iron-containing reducing agent.

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