Application of a dual-effect repair agent based on electrolytic manganese residue in the remediation of heavy metal contaminated soil

Abstract

The present invention relates to the technical field of environmental heavy metal soil remediation, and particularly relates to the application of a remediation agent based on electrolytic manganese residue in the remediation of heavy metal contaminated soil. The present invention uses electrolytic manganese residue as the base material, mixes it with iron-containing materials and modifies it by ball milling, and utilizes the silicate components and iron and manganese elements therein to passivate heavy metal ions in the soil, which can not only promote the passivation of soil heavy metals, but also increase the content of medium elements such as calcium, magnesium, sulfur, silicon and manganese in the soil, enhance the fertilizer efficiency of the soil. It only needs to mix the electrolytic manganese residue-based remediation agent into the heavy metal contaminated soil without other operations, which has important environmental benefits and social values, and provides certain technical guidance for the resource utilization and harmless treatment of electrolytic manganese residue.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental heavy metal soil remediation, and particularly relates to the application of a dual-effect remediation agent based on electrolytic manganese residue in the remediation of heavy metal contaminated soil. Background Art

[0002] In the growing process of industrial and mining activities, a large amount of waste residue will be generated, which is piled up in mines or around factories. Through air settlement, rain leaching, dust diffusion, etc., it will pollute the soil around mines or factories, causing heavy metal pollution around them, thus affecting human life and production activities.

[0003] Electrolytic manganese residue is the acid leaching residue produced after ore powder is acid leached with sulfuric acid during the production of electrolytic manganese. The electrolytic manganese industry is a highly polluting industry, and a large amount of solid waste residue will be generated during the production of electrolytic manganese, causing environmental pollution.

[0004] At present, the remediation of farmland soil mainly uses mineral (like) materials for remediation, but it faces implementation pain points such as high cost, complex construction, and low long-term effectiveness. Therefore, it is urgent to develop a long-term, economical, and safe soil heavy metal remediation agent.

[0005] At present, the existing research on the treatment of heavy metal contaminated land at home and abroad mainly uses pure substances such as ferrous sulfate to be compounded into a passivator to repair and stabilize heavy metals in the soil. However, since most of the compounds composed of pure chemical agents themselves have chemical toxicity, once used improperly, it is easy to pollute the soil. Moreover, most passivators are for single heavy metal contaminated soil or relatively similar heavy metal contaminated soil, and there is less research on soil contaminated by multiple heavy metals. Summary of the Invention

[0006] Aiming at the deficiencies existing in the prior art, the purpose of the present invention is first to provide the application of a dual-effect remediation agent based on electrolytic manganese residue in the remediation of heavy metal contaminated soil.

[0007] The substances in electrolytic manganese residue can be activated to become substances containing muscovite and other similar silicate substances. Therefore, the prospect of using electrolytic manganese residue to remove and passivate heavy metal ions in the soil is broad. Using electrolytic manganese residue as the base material to prepare a remediation agent for the remediation of heavy metal contaminated soil is a method of resource utilization of materials that were originally waste, which can effectively alleviate heavy metal pollution in the soil.

[0008] In order to achieve the above purpose, the present invention proposes the following technical solutions:

[0009] The present invention provides an application of a dual-effect repair agent based on electrolytic manganese residue in the remediation of heavy metal contaminated soil. The repair agent is a mixture of electrolytic manganese residue and iron-containing materials, and the iron-containing materials are selected from at least one of pyrite, FeSO 4 and reduced iron powder. Further, the heavy metals in the heavy metal contaminated soil include at least one of cadmium, chromium, lead and arsenic.

[0010] Further, the mass ratio of the electrolytic manganese residue to the iron-containing material is (0.5-3):1; the preferred mass ratio is (1-1.5):1.

[0011] Further, the specific operation of the application is: mixing the repair agent into the heavy metal contaminated soil according to a mass ratio of 0.2%-5%.

[0012] When the above dual-effect repair agent based on electrolytic manganese residue is applied to heavy metal contaminated soil, it can not only promote the passivation of soil heavy metals, but also increase the content of nutrient elements such as calcium, magnesium and sulfur in the soil, enhancing the fertilizer efficiency of the soil. At the same time, the application process of this repair agent is easy to implement, without cumbersome objective conditions, can be applied to a variety of heavy metal contaminated soil environments, and has a low implementation cost. This material can not only increase the content of medium elements such as calcium, magnesium, sulfur, silicon and manganese in the soil, enhancing the fertilizer efficiency of the soil, but also passivate the heavy metals in the soil.

[0013] The present invention also provides a preparation method of the above dual-effect repair agent based on electrolytic manganese residue, which sequentially includes the following steps:

[0014] S1 Mixing

[0015] Mix the electrolytic manganese residue and the iron-containing material in a certain proportion to obtain a mixture;

[0016] S2 Ball milling

[0017] Put the mixture obtained in step S1 into a ball mill, carry out ball milling, and then take out the milled solid for grinding and screening to obtain the dual-effect repair agent.

[0018] Preferably, the ball milling time is 1-5 h, and the ball milling speed is 200-600 r / min.

[0019] Most preferably, the iron-containing material is reduced iron powder, the mass ratio of the electrolytic manganese residue to the reduced iron powder is 1:1, the ball milling speed is 500 r / min, the ball milling time is 1 h, and the ball-to-material ratio is 10:1.

[0020] The mechanism of the electrolytic manganese residue-based repair agent adsorbing soil heavy metals is:

[0021] The electrolytic manganese residue contains relatively high contents of silicon dioxide and manganese dioxide. After being mixed with iron substances in the ore and ball mill activated, it is activated into silicate substances, and the contents of divalent iron ions and sulfur are also increased. Then, after contacting with heavy metal contaminated soil, the active groups in the activated electrolytic manganese residue will first react with divalent positive ions such as lead, cadmium, and copper in the heavy metal contaminated soil, and then the activated calcium ions and iron ions are slowly released and combined with arsenic in the soil, so that the arsenic in the soil is fixed by the iron and manganese elements in the electrolytic manganese residue and the iron-containing material, thereby reducing the mobility of arsenic, stabilizing its fixation, and reducing its leaching toxicity. On the other hand, it can also increase the medium nutrient elements such as calcium, magnesium, and sulfur in the soil.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] A double-effect repair agent using electrolytic manganese residue as the base material disclosed by the present invention has the characteristics of simple preparation method, convenient operation, no secondary pollution, good adsorption effect and passivation effect, low cost, and excellent adsorption performance for toxic heavy metal ions at normal temperature, providing a new idea for the resource utilization of electrolytic manganese residue, having important environmental benefits and good application prospects.

[0024] The present invention is a material using electrolytic manganese residue as the base material, mixing the electrolytic manganese residue and iron ore together, and through modification, using the components therein to passivate heavy metal ions in the soil, having important environmental benefits and social value. Description of the Drawings

[0025] Figure 1 is the XRD pattern of the electrolytic manganese residue (EMR) used in the example. The numbers in the figure are respectively: 1 - calcium carbonate, 2 - dolomite, 3 - jennite, 4 - quartz, 5 - gypsum, 6 - rankinite, 7 - rhodonite;

[0026] Figure 2 is the XRD pattern of the repair agent obtained in Example 1. The numbers in the figure are respectively: 1 - FeOOH, 2 - CaCO 3 , 3 - Ca(OH) 2 , 4 - Ca 2 SiO 4 , 5 - FeS 2 , 6 - SiO 2 , 7 - MnSiO 3 , 8 - MnO 2 , 9 - CaSO 4 ·0.5H 2 O.

[0027] By Figure 1 and 2It can be seen that the crystal phases of electrolytic manganese residue are mainly quartz, gypsum, xonotlite, tobermorite and rhodonite. After adding iron ore and then ball milling for activation, its crystal form becomes amorphous, and the iron element in the original electrolytic manganese residue also turns into ferrihydrite (FeOOH), along with manganese dioxide and calcium-containing compounds, forming a calcium-manganese-iron complex, which helps to passivate and repair arsenic in the soil.

[0028]

[0029]

[0030] 2FeS 2 +2H 2 O+7O 2 →2Fe 2+ +4SO 4 2- +4H + (3)

[0031] 4Fe 2+ +O 2 +8OH - →4FeOOH+2H 2 O (4)

[0032] 4Fe 2+ +O 2 +4H + →4Fe 3+ +2H 2 O (5)

[0033] 2MnO+O 2 →2MnO 2 (6)

[0034] MnSO 4 +2OH - →Mn(OH) 2 +SO 4 2- (7)

[0035] AsO 4 3- +FeOOH→FeAsO 4 +H 2 O (8)

[0036] 2AsO 4 3- +3Ca 2+ →Ca 3 (AsO 4 ) 2 (9) Specific implementation methods

[0037] The present invention will be further described in detail below in conjunction with specific embodiments, so that those skilled in the art can understand the present invention more clearly.

[0038] The following embodiments are only used to illustrate the present invention, but not to limit the scope of the present invention. Based on the specific embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0039] In the following embodiments, the raw materials used: electrolytic manganese residue (EMR) comes from CITIC Dameng Manganese Mining Co., Ltd., and its particle size is 149 μm; the electrolytic manganese residue is analyzed by XRF test (X-ray fluorescence spectrometer: Zetium, Netherlands, PANalytical B.V) for the analysis of the component weight percentage content, and the results are shown in the following table:

[0040] Table 1

[0041] Sample MgO <![CDATA[Al 2 O 3 > <![CDATA[SiO 2 > CaO <![CDATA[Fe 2 O 3 > <![CDATA[Sodium 2 O]]> <![CDATA[P 2 O 5 > <![CDATA[CO 2 > <![CDATA[SO 3 > <![CDATA[K 2 O]]> MnO EMR / % 1.73 1.85 17.59 13.20 7.05 0.11 0.27 19.95 31.80 0.81 5.33

[0042] Example 1 Preparation of an electrolytic manganese residue-based remediation agent, the steps are as follows:

[0043] S1 Mixing

[0044] Take 6 g of electrolytic manganese residue and 4 g of pyrite (composition: 55.88% Fe, 35.55% S, 2.28% Si) and mix them to obtain a mixture;

[0045] S2 Ball milling

[0046] Put the mixture obtained in step S1 into a ball mill, with a ball-to-material ratio of 10:1, ball mill for 2 h at 500 r / min, then take out the obtained solid and grind it, and pass through a 100-mesh sieve to obtain the remediation agent for later use.

[0047] Put 0.02 g of the above-mentioned remediation agent into 0.02 L of arsenic acid and As 2 O 3 solutions with an initial arsenic concentration of 50 mg / L respectively. After turning and shaking at room temperature for 1 h, filter, and use an atomic spectrophotometer to measure the remaining arsenic content. It is calculated that: the adsorption capacity of the above-mentioned remediation agent for As(V) is 35.10 mg / g, and the adsorption capacity for As(III) is 29.11 mg / g.

[0048] Apply the prepared remediation agent to the heavy metal-contaminated soil for soil remediation performance detection.

[0049] Specifically, take the heavy metal seriously contaminated soil (with a moisture content of 60%) from a certain mining area in Hubei. The heavy metal content in this soil is shown in Table 2.

[0050] Table 2 Heavy metal content in soil

[0051]

[0052] Take 100 g of the above soil and mix it evenly with 3 g of the remediation agent, then cultivate it at room temperature for 10 d - 30 d. During the cultivation process, stir the soil irregularly, and at the same time, replenish water in a timely manner to maintain the soil moisture content at the moisture content of the original soil all the time. Then, use the TCLP leaching method to extract heavy metals and conduct analysis and detection. The results are shown in Table 3.

[0053] Table 3 Concentrations of heavy metals extracted by the TCLP leaching method (TCLP, μg / L)

[0054] Cr As Cd Pb Ni Cu Before repair 370.65 62.81 131.65 612.28 192.47 729.29 10d 25.92 7.87 71 32.08 171.13 323.02 20d 15.63 7.2 61.05 69.94 111.25 384.25 30d 19.29 8.82 73.73 21.91 169.93 412.16

[0055] In the table, 10 d, 20 d, and 30 d respectively represent that in the above experiment, the soil was cultivated at room temperature for 10 d, 20 d, and 30 d.

[0056] It can be seen from the data in the above table that the remediation agent prepared in this example has a passivation effect on various heavy metals in the soil, significantly reducing the leaching toxicity of Cr, As, Cd, Pb, Ni, Cu, etc. in the contaminated soil. At the same time, the results of monitoring the leaching amount of manganese in the soil show that with the increase of the incubation time, the leaching amount of manganese in the soil does not increase.

[0057] Example 2 Preparation of an electrolytic manganese slag-based remediation agent, the steps are as follows:

[0058] S1 Mixing

[0059] Take 5 g of electrolytic manganese slag and 5 g of reduced iron powder and mix them to obtain a mixture;

[0060] S2 Ball milling

[0061] Put the mixture obtained in step S1 into a ball mill, with a ball-to-material ratio of 10:1, ball mill for 1 h at 500 r / min, then take out the obtained solid and grind it, and pass it through a 100-mesh sieve to obtain the remediation agent for later use.

[0062] Put 0.02 g of the above remediation agent into 0.02 L of arsenic acid and As 2 O 3 solutions with an initial arsenic element concentration of 50 mg / L respectively. After turning and oscillating at room temperature for 1 h, filter, and use an atomic spectrophotometer to measure the remaining arsenic content, and calculate that: the adsorption capacity of the above remediation agent for As(V) is 35.10 mg / g, and the adsorption capacity for As(III) is 39.11 mg / g.

[0063] The prepared remediation agent was applied to heavy metal - contaminated soil for soil remediation performance detection. Specifically, soil severely contaminated with heavy metals and the same soil sampled together with Example 1 were taken.

[0064] After taking 10 g of the above - mentioned soil and mixing it evenly with 0.3 g of the remediation agent, it was cultured at room temperature for 1 d. During the culturing process, the soil was stirred irregularly, and at the same time, water was added in a timely manner to maintain the soil moisture content at 60% all the time. Then, the TCLP leaching method (the same as in Example 1) was used to extract heavy metals and conduct analysis and detection. The results are shown in Table 4.

[0065] Table 4 Heavy metal concentration extracted by the TCLP leaching method (TCLP, μg / L)

[0066] Cr As Cd Pb Ni Cu Before repair 370.65 62.81 131.65 612.28 192.47 729.29 1d 40.46 0.89 29.33 52.09 138.63 223.02

[0067] From the data in the above table, it can be seen that the remediation agent prepared in this example has a passivation effect on various heavy metals in the soil, significantly reducing the leaching toxicity of Cr, As, Cd, Pb, Ni, Cu, etc. in the contaminated soil. At the same time, the results of monitoring the leaching amount of manganese in the soil show that with the increase of the incubation time, the leaching amount of manganese in the soil does not increase.

[0068] Example 3 Preparation of an electrolytic manganese slag - based remediation agent, the steps are as follows:

[0069] S1 Mixing

[0070] Take 5 g of electrolytic manganese slag and 5 g of FeSO 4 Mix to obtain a mixture;

[0071] S2 Ball - milling

[0072] Put the mixture obtained in step S1 into a ball mill, with a ball - to - material ratio of 10:1. After ball - milling at 500 r / min for 1 h, take out the obtained solid, grind it, and pass it through a 100 - mesh sieve to obtain the remediation agent for standby.

[0073] Put 0.02 g of the above - mentioned remediation agent into 0.02 L of arsenic acid and As 2 O 3 solutions with an initial arsenic element concentration of 50 mg / L respectively. After turning and oscillating at room temperature for 1 h, filter, and use an atomic spectrophotometer to measure the remaining arsenic content. It is calculated that: the adsorption capacity of the above - mentioned remediation agent for As(V) is 26.55 mg / g, and the adsorption capacity for As(III) is 30.11 mg / g.

[0074] The prepared remediation agent was applied to heavy metal - contaminated soil for soil remediation performance detection. Specifically, soil severely contaminated with heavy metals and the same soil sampled together with Example 1 were taken.

[0075] After mixing 10 g of the above soil evenly with 0.3 g of the remediation agent, incubate it at room temperature for 1 day. During the incubation process, stir the soil irregularly, and replenish water in a timely manner to maintain the soil moisture content at 60% all the time. Then, use the TCLP leaching method (the same as in Example 1) to extract heavy metals and conduct analysis and detection. The results are shown in Table 5.

[0076] Table 5 Heavy metal concentrations extracted by the TCLP leaching method (TCLP, μg / L)

[0077] Cr As Cd Pb Ni Cu Before repair 370.65 62.81 131.65 612.28 192.47 729.29 1d 53.49 5.57 56.86 45.60 138.09 223.02

[0078] From the data in the above table, it can be seen that the remediation agent prepared in this example has a passivation effect on various heavy metals in the soil, significantly reducing the leaching toxicity of Cr, As, Cd, Pb, Ni, Cu, etc. in the contaminated soil. At the same time, the results of monitoring the leaching amount of manganese in the soil show that with the increase of the incubation time, the leaching amount of manganese in the soil does not increase.

[0079] Comparative Example 1

[0080] After ball-milling electrolytic manganese slag at 400 r / min for 2 h, take out the obtained solid, grind it, and pass it through a 100-mesh sieve to obtain the ball-milled electrolytic manganese slag for later use.

[0081] Put 0.02 g of the ball-milled electrolytic manganese slag into 0.02 L of arsenic acid and As 2 O 3 solutions with an initial arsenic element concentration of 50 mg / L respectively. After turning and shaking at room temperature for 1 h, filter, and use an atomic spectrophotometer to measure the remaining arsenic content. It is calculated that the adsorption capacity of the ball-milled electrolytic manganese slag for As(V) is 5 mg / g, and the adsorption capacity for As(III) is 6 mg / g.

[0082] Apply the prepared ball-milled electrolytic manganese slag to the heavy metal-contaminated soil for soil remediation performance detection. Specifically, take the soil severely contaminated with heavy metals, which is the same soil sampled together with Example 1. After mixing 100 g of the above soil evenly with 3 g of the ball-milled electrolytic manganese slag, incubate it at room temperature for 10 days. During the incubation process, stir the soil irregularly, and replenish water in a timely manner to maintain the soil moisture content at the moisture content of the original soil all the time. Then, use the TCLP leaching method (the same as in Example 1) to extract heavy metals and conduct analysis and detection. The results are shown in Table 6.

[0083] Table 6 Influence of ball-milled electrolytic manganese slag on heavy metal concentrations in contaminated soil (TCLP, μg / L)

[0084]

[0085]

[0086] Conclusion: The leaching toxicity of heavy metals in the soil treated with ball-milled electrolytic manganese residue has decreased, but not as much as that after mixing. This indicates that the ball-milled electrolytic manganese residue also has a passivation effect on heavy metals in the soil, but the passivation effect is weaker than that of mixing.

[0087] Comparative Example 2

[0088] Put 0.02 g of electrolytic manganese residue into 0.02 L of arsenic acid and As 2 O 3 solutions with an initial arsenic concentration of 50 mg / L each. After turning and shaking at room temperature for 1 h, filter, and use an atomic spectrophotometer to measure the remaining arsenic content. It is calculated that the adsorption capacity of the electrolytic manganese residue for As(V) is 0.90 mg / g, and the adsorption capacity for As(III) is 4.29 mg / g.

[0089] Apply the electrolytic manganese residue to the heavy metal-polluted soil for soil remediation performance testing. Specifically, take the soil severely polluted with heavy metals, which is the same soil sampled together with Example 1. Mix 100 g of the above soil with 3 g of electrolytic manganese residue evenly, and incubate at room temperature for 10 d. During the incubation process, stir the soil irregularly, and at the same time, add water in a timely manner to maintain the water content in the soil at 60% all the time. Then, use the TCLP leaching method (the same as in Example 1) to extract heavy metals and conduct analysis and testing. The results are shown in Table 7.

[0090] Table 7 Effects of electrolytic manganese residue on the heavy metal concentration in polluted soil (TCLP, μg / L)

[0091]

[0092]

[0093] Conclusion: The leaching toxicity of heavy metals in the soil treated with the original electrolytic manganese residue has decreased, but not as much as that after mixing. This indicates that the ball-milled electrolytic manganese residue also has a passivation effect on heavy metals in the soil, but the passivation effect is weaker than that of mixing.

[0094] In the present invention, the electrolytic manganese residue is combined with iron-containing materials, and the two are prepared into a soil remediation agent after mechanical ball milling. On the one hand, it can not only save costs but also avoid secondary pollution of the electrolytic manganese residue, and can be used to repair soil heavy metal pollution. On the other hand, the nitrogen element in the remediation agent can be slowly released into the soil over time, providing a large amount of nutrients for the growth of plants in the soil, thereby further improving the soil environment polluted by heavy metals.

Claims

1. Application of a dual-effect remediation agent based on electrolytic manganese residue in remediation of heavy metal contaminated soil. The dual-effect remediation agent is a mixture of electrolytic manganese residue and iron-containing materials, and the iron-containing materials are selected from at least one of pyrite, FeSO 4 and reduced iron powder; The heavy metals in the heavy metal contaminated soil include at least one of cadmium, chromium, lead and arsenic; It is characterized in that The specific operation of the application is: mixing the dual-effect repair agent into the heavy metal contaminated soil according to the mass ratio of 0.2% to 5%; The dual-effect repair agent based on electrolytic manganese residue is prepared by the following method: S1 Mixing Mixing the electrolytic manganese residue and the iron-containing material according to the mass ratio of (0.5~3):1 to obtain a mixture; S2 Ball milling Putting the mixture obtained in step S1 into a ball mill for ball milling, and then taking out the ball-milled solid, grinding and sieving to obtain the dual-effect repair agent.

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