A resource-based treatment method for manganese-containing wastewater

Abstract

The present invention provides a resource-based treatment method for manganese-containing wastewater, comprising the steps of: S1, adding an alkaline regulator to the manganese-containing wastewater to obtain a first treatment solution having a pH of 9.3-9.65; wherein the manganese-containing wastewater contains manganese ions, calcium ions, and magnesium ions, and the concentration of the manganese ions is 80-500 mg / L, and the mass of the manganese ions is less than the mass of the calcium and magnesium ions; S2, adding a flocculant to the first treatment solution and performing a first mixing to obtain a second treatment solution having a pH of 9.0-9.5; S3, adding hypochlorite to the second treatment solution and performing a second mixing, and solid-liquid separation to obtain a manganese-containing final precipitate and a manganese-removing water body. The present invention can reduce the amount of reagent used while suppressing calcium-magnesium co-precipitation; the present invention can also selectively and efficiently precipitate manganese ions, and the grade of the manganese precipitate is high, the pH of the manganese-removing water body is less than 9, and neither manganese ions nor residual chlorine exceeds the standard.

Description

Technical Field

[0001] The present invention relates to the field of wastewater treatment, and in particular to a method for resource recovery of manganese-containing wastewater. Background Art

[0002] Manganese mine water discharges in extremely high volumes and exhibits high manganese concentrations (80-500 mg / L). It is also rich in calcium and magnesium ions, forming a complex multi-ion system. Currently, the primary method for removing manganese from manganese-containing wastewater is chemical precipitation; for example, this involves adding an alkaline conditioner, such as sodium hydroxide, to the wastewater to precipitate and separate the manganese.

[0003] Although the existing chemical precipitation method can achieve the precipitation of manganese ions in manganese-containing wastewater, this method has significant defects under the water quality conditions of typical manganese mine water. Since the total amount of calcium, magnesium and other ions in manganese mine water is usually much greater than that of manganese ions, and they are all prone to precipitate under alkaline conditions, an excessive amount of alkaline regulator must be added to maintain the precipitation environment in order to maintain a high removal rate of manganese ions.

[0004] However, in this case, a large amount of alkaline regulator will be used, resulting in the simultaneous precipitation of a large amount of calcium and magnesium ions. Not only will the reagent be wasted seriously, but the manganese ions cannot be separated separately, resulting in solid waste containing calcium and magnesium impurities, which will cause the risk of secondary pollution and affect the grade of manganese in the precipitate, making it difficult to utilize resources. Although sodium fluoride can be used to pre-remove calcium and magnesium, it will further increase the overall cost. At the same time, this method will introduce F - To avoid residual waste, a fluorine removal process needs to be added in the later stage of treatment, which further increases the overall cost.

[0005] In view of this, it is necessary to provide a resource-based treatment method for manganese-containing wastewater to solve or at least alleviate the technical problem of how to reduce the amount of reagents used and efficiently precipitate manganese ions while inhibiting calcium and magnesium co-precipitation. Summary of the Invention

[0006] The main purpose of the present invention is to provide a resource-based treatment method for manganese-containing wastewater, aiming to solve the technical problems of suppressing calcium and magnesium co-precipitation while reducing the amount of reagents used and efficiently precipitating manganese ions.

[0007] To achieve the above object, the present invention provides a method for resource recovery of manganese-containing wastewater, comprising the steps of:

[0008] S1, adding an alkaline regulator to the manganese-containing wastewater to obtain a first treated liquid with a pH of 9.3-9.65;

[0009] The manganese-containing wastewater contains manganese ions, calcium ions, and magnesium ions; the concentration of the manganese ions in the manganese-containing wastewater is 80-500 mg / L; the mass of the manganese ions is less than the mass of the calcium and magnesium ions, and the mass of the calcium and magnesium ions is the sum of the masses of the calcium ions and the magnesium ions;

[0010] S2, adding a flocculant to the first treated liquid and performing a first mixing to obtain a second treated liquid with a pH of 9.0-9.5;

[0011] S3, adding hypochlorite to the second treated liquid and performing a second mixing, and performing solid-liquid separation to obtain a manganese-containing final precipitate and manganese-removed water.

[0012] Furthermore, the alkaline regulator includes one or more of sodium hydroxide, potassium hydroxide, and calcium oxide.

[0013] Furthermore, the flocculant includes one or more of polyacrylamide, polyaluminum chloride, and polyferric sulfate; the mass percentage of the flocculant to the manganese-containing wastewater is 0.1-1‰.

[0014] Furthermore, the hypochlorite includes one or more of sodium hypochlorite, potassium hypochlorite, and calcium hypochlorite; and the molar ratio of the hypochlorite to the manganese ions in the second treatment solution is 1.1-3.2:1.

[0015] Furthermore, the duration of the first mixing is 40-80 minutes.

[0016] Furthermore, the duration of the second mixing is not less than 20 minutes.

[0017] Furthermore, the step S2 further comprises: performing solid-liquid separation on the second treatment liquid to obtain a manganese-containing intermediate precipitate and the second treatment liquid after solid-liquid separation.

[0018] Furthermore, the step S3 further includes: after completing the second mixing, adding part of the manganese-containing intermediate precipitate, and then performing a third mixing; the mass proportion of the part of the manganese-containing intermediate precipitate in the manganese-containing intermediate precipitate is 10-30%; and the duration of the third mixing is not less than 5 minutes.

[0019] Furthermore, the molar ratio of the hypochlorite to the manganese ions in the second treatment solution is 1.1-1.8:1.

[0020] Furthermore, no solid-liquid separation is performed in step S2; and the molar ratio of the hypochlorite to the manganese ions in the second treatment liquid is 2.3-3.2:1.

[0021] Compared with the prior art, the present invention has at least the following advantages:

[0022] The present invention can selectively and efficiently precipitate manganese ions, reduce the amount of reagents used, and the grade of manganese precipitates is high. The pH of the manganese-removed water body is less than 9, and both manganese ions and residual chlorine do not exceed the standard. Specifically, in the chemical precipitation stage, based on the solubility product difference between manganese, calcium, and magnesium ions, the present invention can reduce the amount of alkaline regulator used while suppressing the co-precipitation of calcium and magnesium, and can efficiently and selectively precipitate manganese ions with high grade. The present invention selectively precipitates manganese ions by precisely controlling the pH, so that dissolved manganese mainly generates manganese hydroxide, while avoiding the simultaneous precipitation of calcium and magnesium, thereby significantly reducing the amount of alkaline regulator used and significantly increasing the proportion of manganese hydroxide in the precipitate. The manganese is of higher grade and can be utilized as a resource.

[0023] In the subsequent oxidation stage, based on the differences in oxidation properties between multivalent manganese and calcium and magnesium, the present invention primarily uses hypochlorite for targeted deep oxidation to remove manganese. On the one hand, this process produces essentially no calcium and magnesium precipitation, instead primarily producing manganese oxide, resulting in a high-grade manganese precipitate. On the other hand, because chemical precipitation removes a significant amount of manganese, the amount of residual manganese ions during oxidation removal is minimal, significantly reducing the amount of hypochlorite used, further avoiding a significant increase in the total amount of reagents used, and effectively controlling the generation of new pollution during the oxidation process.

[0024] By using hypochlorite as an oxidant, the present invention achieves synergistic effects in the precipitation-oxidation reaction, avoiding the step of adding alkali to adjust the solution pH during the traditional oxidation process. Furthermore, the present invention can spontaneously adjust the pH to lower the effluent pH. Because the present invention precisely controls the pH of the precipitation reaction in the early stages, the hypochlorite oxidation reaction is at the optimal solution pH, enhancing oxidation activity. This eliminates the need for additional pH adjustment and ensures that both manganese ions and residual chlorine in the effluent meet standards. Furthermore, the hypochlorite oxidation process effectively adjusts the pH, achieving linked pH control, eliminating the traditional step of adding acid to adjust the effluent pH during the precipitation process.

[0025] Furthermore, after oxidation, the present invention can use a trace amount of manganese-containing intermediate precipitate (manganese hydroxide) for internal circulation and reuse in the oxidation effluent, thereby controlling the residual chlorine content and improving the effluent quality. In the present invention, since only the manganese-containing intermediate precipitate is reused in the oxidation effluent, the manganese-containing intermediate precipitate will not increase the amount of hypochlorite added, and the grade and process of the manganese-containing final precipitate will be less affected.

[0026] The present invention innovatively establishes a synergistic system of "pH regulation-directional oxidation" and couples it with the idea of "manganese hydroxide internal circulation chlorine control". Under the condition of no secondary pollution, it innovatively realizes the efficient precipitation of manganese ions and deep purification of manganese in wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0028] Figure 1 This is the XRD pattern of the manganese-containing intermediate precipitate in Example 1 of the present invention;

[0029] Figure 2 This is the XRD pattern of the manganese-containing final precipitate in Example 1 of the present invention;

[0030] Figure 3 This is the XRD pattern of the manganese-containing final precipitate in Example 3 of the present invention.

[0031] The realization of the objectives, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0033] Moreover, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0034] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. Any prior art methods, devices, and materials similar or equivalent to those described in the examples of the present invention may also be used to implement the present invention.

[0035] The present invention provides a method for resource recovery of manganese-containing wastewater, comprising the steps of:

[0036] S1, adding an alkaline regulator to the manganese-containing wastewater to obtain a first treated liquid with a pH of 9.3-9.65.

[0037] In the present invention, the pH of the first treatment liquid is further 9.3-9.6 or 9.55-9.65 or 9.55-9.62 or 9.58-9.62 or 9.3-9.5 or 9.3-9.4 or 9.4-9.5; in the present invention, the alkaline regulator is added to the manganese-containing wastewater to directly adjust the pH of the first treatment liquid.

[0038] In the present invention, the manganese-containing wastewater contains manganese ions, calcium ions, and magnesium ions; in the manganese-containing wastewater, the concentration of the manganese ions is 80-500 mg / L, further 80-300 mg / L, further 100-300 mg / L, further 100-200 mg / L or 100-150 mg / L or 200-300 mg / L; the mass of the manganese ions is less than the mass of the calcium and magnesium ions, and the mass of the calcium and magnesium ions is the sum of the masses of the calcium ions and the magnesium ions; further, the mass ratio of the manganese ions to the calcium and magnesium ions is 1:3-10, further 1:6-8 or 1:3-4.

[0039] Specifically, the manganese-containing wastewater in the present invention is manganese mine water; in the manganese-containing wastewater, the concentration of calcium ions is 200-600 mg / L, further 400-600 mg / L, further 400-500 mg / L; the concentration of magnesium ions is 100-500 mg / L, further 300-500 mg / L, further 300-400 mg / L.

[0040] In the present invention, since manganese ore water contains a large amount of calcium and magnesium ions, if manganese ions are to be efficiently precipitated using an alkaline regulator, a large amount of calcium and magnesium ions will inevitably be precipitated. Therefore, it is necessary to find a suitable reaction node that ensures the initial precipitation of manganese ions while preventing the large amount of calcium and magnesium ions from being precipitated, and is also compatible with the hypochlorite oxidation process. In this case, hypochlorite is then used to deeply remove manganese ions, without causing the large-scale use of hypochlorite or excessive residual chlorine, and the pH can be adjusted back.

[0041] In the present invention, the alkaline regulator comprises one or more of sodium hydroxide, potassium hydroxide, and calcium oxide; further, the alkaline regulator comprises sodium hydroxide. The molar ratio of the alkaline regulator to the manganese ions in the manganese-containing wastewater is 2.5-3.1:1, further 2.6-3:1, 2.6-2.8:1, 2.8-3:1, 2.9-3:1, or 2.9-3.1:1.

[0042] S2, adding a flocculant to the first treatment liquid and performing a first mixing to obtain a second treatment liquid with a pH of 9.0-9.5; the pH of the second treatment liquid is further 9.1-9.4, further 9.1-9.3 or 9.3-9.4.

[0043] In the present invention, after obtaining the first treatment liquid, the flocculant is directly added to the first treatment liquid and then the first mixing is performed.

[0044] In the present invention, the flocculant includes one or more of polyacrylamide, polyaluminum chloride, and polyferric sulfate; further, the flocculant includes polyacrylamide (PAM). The mass percentage of the flocculant to the manganese-containing wastewater is 0.1-1‰, further 0.4-1‰, further 0.5-1‰, or 0.4-0.6‰. In specific implementations, the flocculant is added to the first treatment liquid in the form of a flocculant liquid; the mass concentration of the flocculant in the flocculant liquid can be 0.01-1%, further 0.05-0.15%, and the volume percentage of the flocculant liquid to the first treatment liquid can be 0.1-5%, further 0.1-1%.

[0045] In the present invention, in order to achieve selective removal of manganese and better match the subsequent oxidation, the duration of the first mixing is 40-80 minutes, and further 50-70 minutes.

[0046] S3. Add hypochlorite to the second treated liquid, perform a second mixing, and perform solid-liquid separation to obtain a manganese-containing final precipitate and manganese-removed water (effluent). In the manganese-containing final precipitate of the present invention, manganese is mainly present in the form of oxides. The pH of the manganese-removed water is less than 9, further 8.1-8.9, further 8.2-8.8, further 8.2-8.3, 8.3-8.5, 8.5-8.7, or 8.7-8.8.

[0047] In the manganese removal water, the content of manganese ions is less than 2 mg / L, further less than 0.6 mg / L, further less than 0.5 mg / L; the residual chlorine is less than 0.5 mg / L, further less than 0.3 mg / L, further less than 0.2 mg / L, further less than 0.15 mg / L.

[0048] In the present invention, after obtaining the second treatment liquid, the hypochlorite is directly added to the second treatment liquid and then the second mixing is performed. In the present invention, the hypochlorite includes one or more of sodium hypochlorite, potassium hypochlorite, and calcium hypochlorite; further, the hypochlorite includes sodium hypochlorite. In the present invention, by using the hypochlorite, the pH value of the water body can be adjusted back, thereby reducing the alkalinity of the water body. In the present invention, the molar ratio of the hypochlorite to the manganese ions in the second treatment liquid is 1.1-3.2:1, further 1.3-3.2:1, further 1.5-3:1 or 1.1-1.8:1 or 1.3-1.8:1 or 2.3-3.2:1 or 1.5-1.6:1 or 2.5-3:1.

[0049] In the present invention, the duration of the second mixing is not less than 20 minutes; further, the duration of the second mixing is 20-60 minutes, further 20-40 minutes, or 30-60 minutes, or 30-40 minutes.

[0050] It should be noted that while hypochlorite oxidation can remove manganese, using only hypochlorite oxidation for manganese removal results in excessive hypochlorite dosage, leading to a surge in chemical costs and energy consumption. This makes it difficult to deeply purify high-concentration manganese ions, easily exceeding effluent concentration standards, and creates new pollution risks, such as excessive residual chlorine. Removing manganese from wastewater containing large amounts of calcium and magnesium using only chemical precipitation with alkali not only faces the problem of large chemical dosages but also leads to co-precipitation of calcium and magnesium.

[0051] If the two are used directly in combination, it is necessary to overcome the difficulties of co-precipitation of calcium and magnesium during the precipitation process, as well as how to connect precipitation manganese removal with oxidation manganese removal; it should be noted that if the pH after chemical precipitation is not compatible with the oxidation of hypochlorite, it will also cause manganese ions and residual chlorine to exceed the standard.

[0052] It should be noted that if manganese, calcium and magnesium are removed indiscriminately, the amount of alkaline regulator is bound to be very large; since the present invention selectively removes manganese in the early stage, the amount of alkaline regulator used can be reduced, and the amount of hypochlorite added is related to the manganese ion content during deep manganese removal; therefore, the present invention is equivalent to using a smaller total amount of reagents to achieve the manganese removal effect under a large amount of reagents, and can also overcome the problem of calcium and magnesium co-precipitation, improve the grade of manganese precipitation, adjust the pH, and avoid excessive residual chlorine.

[0053] The present invention utilizes a synergistic precipitation-oxidation process. First, by adding an appropriate amount of alkali and precisely controlling the solution pH, selective precipitation of manganese ions is achieved. A small amount of hypochlorite is then added to oxidize and remove the remaining manganese ions. This coupled process, coupled with "manganese hydroxide internal circulation chlorine control," achieves residual chlorine control. This method significantly reduces the amount of reagents added, is low-cost, and simultaneously enables resource utilization and deep purification of manganese in wastewater such as manganese mine water. It also achieves a high manganese ion recovery rate, high recovered manganese purity, and effluent meets discharge standards, promising promising industrial applications.

[0054] As a supplementary explanation of the present invention:

[0055] In step S2 of the present invention, after obtaining the second treated liquid, solid-liquid separation may or may not be performed; if solid-liquid separation is performed, the manganese-containing intermediate precipitate obtained after the solid-liquid separation may or may not be partially reused after completing the second mixing; the specific analysis is as follows:

[0056] 1. The second treatment liquid is not subjected to solid-liquid separation; in this case, the second treatment liquid contains an intermediate precipitate containing manganese (manganese exists in the form of manganese hydroxide, and manganese exists mainly in the form of manganese hydroxide). During the oxidation process, hypochlorite will react with manganese hydroxide when deep manganese precipitation is carried out, which to a certain extent leads to an increase in the amount of hypochlorite added; however, not performing solid-liquid separation can save process steps and has certain advantages in simplicity.

[0057] 2. The second treatment liquid is subjected to solid-liquid separation, but the manganese-containing intermediate precipitate is not recycled. In this case, due to the solid-liquid separation, the second treatment liquid does not contain the manganese-containing intermediate precipitate. Therefore, when hypochlorite is subsequently added, the amount of hypochlorite added does not need to be increased.

[0058] 3. The second treated liquid is subjected to solid-liquid separation, and after the third mixing, a portion of the manganese-containing intermediate precipitate is reused; in this case, the reused manganese-containing intermediate precipitate can reduce the residual chlorine content in the final water body; and, in the present invention, the manganese-containing intermediate precipitate is reused only partially after the second mixing is completed, which does not interfere with the deep removal of manganese, does not increase the amount of hypochlorite added, and has little effect on the manganese precipitation during the oxidation process.

[0059] Based on the above supplementary explanation, as a preferred embodiment, step S2 further includes: performing solid-liquid separation on the second treatment liquid to obtain a manganese-containing intermediate precipitate and the second treatment liquid after solid-liquid separation; that is, before performing step S3, the second treatment liquid is subjected to solid-liquid separation to separate the manganese-containing intermediate precipitate.

[0060] Furthermore, step S3 further includes: after completing the second mixing, adding a portion of the manganese-containing intermediate precipitate to the second treated liquid after solid-liquid separation, and then performing a third mixing; the mass proportion of the manganese-containing intermediate precipitate in the intermediate precipitate is 10-30%, preferably 10-20% or 20-30%; and the duration of the third mixing is no less than 5 minutes, preferably 5-15 minutes or 10-15 minutes. Alternatively, in step S3, the manganese-containing intermediate precipitate is not added to the second treated liquid.

[0061] In the above case, the molar ratio of the hypochlorite to the manganese ions in the second treatment solution is 1.1-1.8:1, further 1.3-1.8:1, further 1.4-1.7:1, further 1.5-1.6:1.

[0062] As another embodiment, solid-liquid separation is not performed in step S2 (in this case, the second treatment liquid is not subjected to solid-liquid separation and the hypochlorite is directly added); the molar ratio of the hypochlorite to the manganese ions in the second treatment liquid is 2.3-3.2:1, further 2.5-3:1, 2.8-3.2:1, or 2.3-2.7:1.

[0063] As a further explanation of the present invention: The present invention constructs a process system for treating manganese-containing wastewater such as manganese mine water based on the synergistic effect of "pH regulation-directional oxidation". By precisely controlling the pH value of the system in the manganese precipitation stage, the co-precipitation of calcium and magnesium ions is effectively suppressed while achieving efficient precipitation of manganese ions, breaking through the technical bottleneck of simultaneous precipitation of calcium and magnesium metal ions in traditional processes. For the trace manganese ions remaining after precipitation, hypochlorite oxidation is used to selectively convert dissolved manganese into manganese oxide precipitate. This process not only ensures the deep purification of manganese, but also realizes the resource utilization of manganese through the recyclability of the product, and ultimately achieves the dual goals of resource utilization of manganese elements in wastewater and deep purification of water quality.

[0064] The present invention achieves ultra-efficient recovery and purification of manganese ions from wastewater by constructing a two-stage synergistic "precipitation-oxidation" system. During the precipitation stage, precise pH control is used to preferentially form manganese hydroxide precipitates from manganese ions. During the oxidation stage, residual manganese ions are directed into manganese oxide products, breaking through the technical bottleneck of achieving both high manganese recovery rate and high purity in traditional processes. The present invention ultimately achieves a high recovery rate of manganese ions and a high purity of manganese precipitates, reducing costs by more than 40% compared to existing technologies, forming a full-chain closed-loop solution of "pollution control-resource regeneration-high-value utilization."

[0065] This invention uses a synergistic "precipitation-oxidation" process to treat manganese mine water. By establishing a process system that precisely controls pH and integrates a hypochlorite oxidation reaction, it overcomes the industry challenge of low efficiency in deep manganese ion removal in traditional treatment processes. In the precipitation stage, the invention precisely controls pH to create a manganese-dominant precipitation zone, preferentially forming a manganese-based precipitate (manganese hydroxide). In the enhanced oxidation stage, hypochlorite deeply oxidizes the residual manganese ions to a stable state, MnO2, at room temperature. This results in a stable effluent manganese concentration of less than 2 mg / L, meeting the 2 mg / L limit specified in the Integrated Wastewater Discharge Standard (GB8978-1996).

[0066] The present invention develops a technical system of "manganese hydroxide internal circulation and coordinated chlorine control". By constructing a dynamic coupling mechanism of precipitation product-oxidation reaction, it overcomes the industry problem of excessive residual chlorine and waste of reagents in the traditional hypochlorite oxidation process. The manganese hydroxide precipitate generated in the precipitation stage is innovatively refluxed quantitatively to the oxidation reaction unit, forming a " "The self-purification reaction chain realizes the in-situ reduction of residual chloride ions. Through the self-sustaining chlorine metabolism mechanism of the internal circulation system, the present invention achieves the goal of deep purification of effluent manganese concentration while simultaneously meeting the stringent requirements for residual chlorine in the "Pollutant Discharge Standard for Urban Wastewater Treatment Plants" (GB18918-2002).

[0067] This invention represents a groundbreaking "precipitation-oxidation" process system. By innovatively designing a reagent dosing optimization model and a coordinated reaction pathway control mechanism, it successfully overcomes the technical dilemma of excessive chemical reagent consumption in traditional single-treatment processes. Targeting the characteristics of high-manganese wastewater, this invention pioneers a synergistic mechanism combining an alkaline regulator and hypochlorite: During the pre-precipitation stage, pH control is used to preferentially precipitate manganese ions, reducing manganese concentrations. During the enhanced oxidation stage, manganese ions are converted into high-valent oxides, achieving deep purification of manganese.

[0068] The following are specific examples of the present invention:

[0069] Example 1

[0070] At room temperature, sodium hydroxide was added to the manganese ore gushing water (the molar ratio of sodium hydroxide to manganese ions in the manganese ore gushing water was 3:1), and the pH was controlled at 9.6 to obtain a first treatment liquid; to the first treatment liquid, 0.5% of the volume of the manganese ore gushing water and 0.1% PAM (polyacrylamide) was added, and the reaction was stirred for 60 minutes (at this time, the pH was 9.4, and the concentrations of manganese, calcium, and magnesium were 9.5, 460.3, and 369.5 mg / L after sampling and separation of the precipitate for testing), and precipitate 1 (manganese-containing intermediate precipitate) and a second treatment liquid were separated.

[0071] Table 1 Main ions and concentrations in manganese mine water in a mining area (mg / L)

[0072]

[0073] At room temperature, a sodium hypochlorite solution with a concentration of 10,000 mg / L was added to the second treated liquid at a molar ratio of sodium hypochlorite to residual manganese ions of 1.5:1. After stirring for 30 minutes, precipitate 2 (final precipitate containing manganese) and manganese-removed water (effluent) were separated; in the manganese-removed water, the concentrations of manganese, calcium, and magnesium were 1.7, 458.0, and 365.3 mg / L, respectively, the residual chlorine was 0.46 mg / L, and the pH was 8.7.

[0074] After drying, the contents of manganese, calcium and magnesium in the precipitate 1 (methane-containing intermediate precipitate) of this example were 34.45%, 5.68% and 3.91%, respectively. Figure 1 As shown, it exists mainly in the form of hydroxide.

[0075] After drying, the contents of manganese, calcium and magnesium in the precipitate 2 (final precipitate containing manganese) in this example are 50.83%, 0.59% and 0.28% respectively. Figure 2 As shown, it exists mainly in the form of oxides.

[0076] Example 2

[0077] At room temperature, sodium hydroxide was added to the manganese ore gushing water (same as in Example 1) to control the pH to 9.6 to obtain a first treatment liquid; to the first treatment liquid, 0.5% by mass concentration of 0.1% PAM of the manganese ore gushing water was added, and the reaction was stirred for 60 minutes (at this time, sampling, separation and precipitate were tested, and the concentrations of manganese, calcium, and magnesium were 9.5, 460.3, and 369.5 mg / L, respectively), and precipitate 1 (manganese-containing intermediate precipitate) and a second treatment liquid were separated.

[0078] At room temperature, a sodium hypochlorite solution with a concentration of 10,000 mg / L was added to the second treated liquid at a molar ratio of sodium hypochlorite to residual manganese ions of 1.6:1. After stirring and reacting for 30 minutes, 20% of precipitate 1 (intermediate precipitate containing manganese) was refluxed. After continuing the reaction for 10 minutes, precipitate 2 (final precipitate containing manganese) and manganese-removed water (effluent) were separated. In the manganese-removed water, the concentrations of manganese, calcium, and magnesium were 1.8, 454.7, and 368.1 mg / L, respectively, the residual chlorine was 0.13 mg / L, and the pH was 8.8.

[0079] After drying, the precipitate 2 (final precipitate containing manganese) of this example has manganese, calcium, and magnesium contents of 45.83%, 1.02%, and 0.76%, respectively.

[0080] Example 3

[0081] At room temperature, sodium hydroxide was added to the manganese ore gushing water (same as in Example 1) to control the pH to 9.6 to obtain a first treatment liquid; to the first treatment liquid, 0.5% by mass concentration of 0.1% PAM was added to the manganese ore gushing water, and the mixture was stirred for 60 minutes to obtain a second treatment liquid; sampling, separation, and precipitation were performed and then tested, and the concentrations of manganese, calcium, and magnesium were 9.5, 460.3, and 369.5 mg / L, respectively.

[0082] At room temperature, a sodium hypochlorite solution with a concentration of 10,000 mg / L was added to the second treated liquid at a molar ratio of sodium hypochlorite to residual manganese ions of 2.5:1. After stirring for 30 minutes, the precipitate (final precipitate containing manganese) and manganese-removed water (effluent) were separated; in the manganese-removed water, the concentrations of manganese, calcium, and magnesium were 0.51, 453.5, and 366.8 mg / L, respectively, the residual chlorine was 0.13 mg / L, and the pH was 8.5.

[0083] After drying the manganese-containing final precipitate in this example, the contents of manganese, calcium, and magnesium were 29.33%, 5.16%, and 3.57%, respectively. Figure 3 As shown, it exists mainly in the form of hydroxides and oxides.

[0084] Example 4

[0085] At room temperature, sodium hydroxide was added to the manganese ore gushing water (same as in Example 1) (the molar ratio of sodium hydroxide to manganese ions in the manganese ore gushing water was 2.6:1), and the pH was controlled to 9.3 to obtain a first treatment liquid; to the first treatment liquid, 0.5% by mass concentration of 0.1% PAM was added to the manganese ore gushing water, and the reaction was stirred for 60 minutes to obtain a second treatment liquid, and the pH of the second treatment liquid was 9.1; sampling, separation, and precipitation were performed and then tested, and the concentrations of manganese, calcium, and magnesium were 17.1, 475.3, and 370.5 mg / L, respectively.

[0086] At room temperature, a sodium hypochlorite solution with a concentration of 10,000 mg / L was added to the second treated liquid at a molar ratio of sodium hypochlorite to residual manganese ions of 2.5:1. After stirring for 30 minutes, the precipitate (final precipitate containing manganese) and the manganese-removed water (effluent) were separated; in the manganese-removed water, the concentrations of manganese, calcium, and magnesium were 1.9, 472.8, and 367.3 mg / L, respectively, the residual chlorine was 0.21 mg / L, and the pH was 8.2.

[0087] After drying, the manganese-containing final precipitate of this embodiment has manganese, calcium, and magnesium contents of 36.18%, 4.86%, and 3.39%, respectively.

[0088] Example 5

[0089] At room temperature, sodium hydroxide was added to the manganese ore gushing water (same as in Example 1) (the molar ratio of sodium hydroxide to manganese ions in the manganese ore gushing water was 2.8:1), and the pH was controlled to 9.5 to obtain a first treatment liquid; to the first treatment liquid, 0.5% by mass concentration of 0.1% PAM was added to the manganese ore gushing water, and the reaction was stirred for 60 minutes to obtain a second treatment liquid, and the pH of the second separated liquid was 9.3; sampling, separation, and precipitation were performed and tested, and the concentrations of manganese, calcium, and magnesium were 12.3, 466.5, and 365.2 mg / L, respectively.

[0090] At room temperature, a sodium hypochlorite solution with a concentration of 10,000 mg / L was added to the second treated liquid at a molar ratio of sodium hypochlorite to residual manganese ions of 3:1. After stirring for 30 minutes, the precipitate (final precipitate containing manganese) and the manganese-removed water (effluent) were separated; in the manganese-removed water, the concentrations of manganese, calcium, and magnesium were 0.40, 465.7, and 363.0 mg / L, respectively, the residual chlorine was 0.28 mg / L, and the pH was 8.3.

[0091] After drying, the manganese-containing final precipitate of this embodiment has manganese, calcium, and magnesium contents of 33.38%, 5.12%, and 3.65%, respectively.

[0092] Example 6

[0093] At room temperature, sodium hydroxide was added to manganese ore water from another mining area (manganese concentration was 261.38 mg / L, calcium concentration was 491.75 mg / L, and magnesium concentration was 381.00 mg / L) and the pH was controlled at 9.5 to obtain a first treatment liquid. To the first treatment liquid, 0.5% of the volume of the manganese ore water and 0.1% PAM was added, and the reaction was stirred for 60 minutes to obtain a second treatment liquid. After sampling, separation and precipitation, and then testing, the concentrations of manganese, calcium, and magnesium were 12.8, 444.8, and 336.0 mg / L, respectively.

[0094] At room temperature, a sodium hypochlorite solution with a concentration of 10,000 mg / L was added to the second treated liquid at a molar ratio of sodium hypochlorite to residual manganese ions of 2.5:1. After stirring for 30 minutes, the precipitate (final precipitate containing manganese) and manganese-removed water (effluent) were separated; in the manganese-removed water, the concentrations of manganese, calcium, and magnesium were 1.36, 440.9, and 333.4 mg / L, respectively, the residual chlorine was 0.22 mg / L, and the pH was 8.3.

[0095] After drying, the manganese-containing final precipitate of this embodiment has manganese, calcium, and magnesium contents of 42.81%, 3.28%, and 2.40%, respectively.

[0096] Comparative Example 1

[0097] At room temperature, sodium hydroxide was added to the manganese ore gushing water (same as in Example 1) to control the pH to 9.7 or 9.9 to obtain a first treatment liquid; to the first treatment liquid, 0.5% by mass concentration of 0.1% PAM was added to the manganese ore gushing water, and the mixture was stirred for 60 minutes to separate the manganese-containing final precipitate and the second treatment liquid (effluent).

[0098] In this comparative example, when the pH of the first treatment solution reaches 9.7, the molar ratio of sodium hydroxide to manganese ions in the manganese ore water is 5:1; when the pH of the first treatment solution reaches 9.9, the molar ratio of sodium hydroxide to manganese ions in the manganese ore water is 8:1.

[0099] In this comparative example, only when sodium hydroxide is added in large quantities can the effluent manganese ion concentration be lower than 2 mg / L. However, at this time, a large amount of calcium and magnesium have precipitated, which will greatly reduce the purity of the recovered manganese hydroxide.

[0100] When the pH value of the first treatment liquid is 9.9, after the manganese-containing final precipitate of this comparative example is dried, the contents of manganese, calcium and magnesium are 15.57%, 2.04% and 18.96%, respectively.

[0101] Table 2 Experimental results at different pH

[0102]

[0103] Comparative Example 2

[0104] At room temperature, a sodium hypochlorite solution with a concentration of 10,000 mg / L was added to the manganese mine water (same as in Example 1) at a molar ratio of sodium hypochlorite to manganese ions of 1:1, 1.2:1, or 1.4:1. After stirring for 1 hour, the precipitate and the manganese-removed water (effluent) were separated.

[0105] In this comparative example, when the molar ratio of sodium hypochlorite to manganese ion is 1:1, 1.2:1, and 1.4:1, the manganese concentrations in the manganese removal water are 19.80, 6.38, and 1.69 mg / L, respectively.

[0106] In this comparative example, when the molar ratio of sodium hypochlorite to manganese ion is 1.4:1, the manganese ion content can meet the standard. However, the addition of a large amount of sodium hypochlorite causes a significant increase in cost, and the residual chlorine content in the effluent is 8.22 mg / L, which seriously exceeds the standard and cannot meet the discharge standard.

[0107] Comparative Example 3

[0108] At room temperature, sodium hydroxide was added to the manganese ore gushing water (same as in Example 1) to control the pH to 9.5 to obtain a first treatment liquid; to the first treatment liquid, 0.5% by mass concentration of 0.1% PAM was added to the manganese ore gushing water, and the mixture was stirred for 180 minutes to obtain a second treatment liquid, the pH of which was 8.7; sampling, separation, and precipitation were performed and the concentrations of manganese, calcium, and magnesium were 10.6, 461.1, and 354.8 mg / L, respectively.

[0109] At room temperature, a sodium hypochlorite solution with a concentration of 10,000 mg / L was added to the second treated liquid at a molar ratio of sodium hypochlorite to residual manganese ions of 3:1. After stirring for 30 minutes, the precipitate (final precipitate containing manganese) and manganese-removed water (effluent) were separated. In the manganese-removed water, the concentrations of manganese, calcium, and magnesium were 5.3, 458.6, and 353.5 mg / L, respectively, the residual chlorine was 1.84 mg / L, and the pH was 7.6. Both manganese and residual chlorine exceeded the standard.

[0110] In this comparative example, when the pH of the second treatment liquid is too low, the oxidation effect of manganese by adding sodium hypochlorite is greatly reduced, and deep purification of manganese cannot be achieved, and the residual chlorine content is relatively high.

[0111] The above technical solutions of the present invention are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for resource recovery of manganese-containing wastewater, characterized in that: Including steps: S1, adding an alkaline regulator to the manganese-containing wastewater to obtain a first treated liquid with a pH of 9.3-9.65; The manganese-containing wastewater contains manganese ions, calcium ions, and magnesium ions; the concentration of the manganese ions in the manganese-containing wastewater is 80-500 mg / L; the mass of the manganese ions is less than the mass of the calcium and magnesium ions, and the mass of the calcium and magnesium ions is the sum of the masses of the calcium ions and the magnesium ions; S2, adding a flocculant to the first treated liquid and performing a first mixing to obtain a second treated liquid with a pH of 9.0-9.5; The step S2 further comprises: performing solid-liquid separation on the second treatment liquid to obtain a manganese-containing intermediate precipitate and the second treatment liquid after solid-liquid separation; S3, adding hypochlorite to the second treated liquid and performing a second mixing, and performing solid-liquid separation to obtain a manganese-containing final precipitate and manganese-removed water; The step S3 further includes: after completing the second mixing, adding a portion of the manganese-containing intermediate precipitate, and then performing a third mixing.

2. The resource recovery method for manganese-containing wastewater according to claim 1, characterized in that: The alkaline regulator includes one or more of sodium hydroxide, potassium hydroxide, and calcium oxide.

3. The resource recovery method for manganese-containing wastewater according to claim 1, characterized in that: The flocculant includes one or more of polyacrylamide, polyaluminum chloride, and polyferric sulfate; the mass percentage of the flocculant to the manganese-containing wastewater is 0.1-1‰.

4. The resource recovery method for manganese-containing wastewater according to claim 1, characterized in that: The hypochlorite includes one or more of sodium hypochlorite, potassium hypochlorite, and calcium hypochlorite; and the molar ratio of the hypochlorite to the manganese ions in the second treatment solution is 1.1-3.2:

1.

5. The resource recovery method for manganese-containing wastewater according to claim 1, characterized in that: The duration of the first mixing is 40-80 minutes.

6. The resource recovery method for manganese-containing wastewater according to claim 1, characterized in that: The duration of the second mixing is not less than 20 minutes.

7. The resource recovery method for manganese-containing wastewater according to claim 1, characterized in that: In the step S3, the mass of the manganese-containing intermediate precipitate accounts for 10-30% of the mass of the manganese-containing intermediate precipitate; and the duration of the third mixing is not less than 5 minutes.

8. The resource recovery method for manganese-containing wastewater according to claim 1, characterized in that: The molar ratio of the hypochlorite to the manganese ions in the second treatment solution is 1.1-1.8:1.

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