Method for promoting improvement of electrolytic manganese residue into soil-like substrate

Abstract

Disclosed in the present invention is a method for promoting the formation of electrolytic manganese residue macroaggregates. The method comprises the following steps: adding bagasse and earthworm manure to a pretreated electrolytic manganese residue sample, uniformly mixing same, adding deionized water to the mixture, and culturing the mixture at room temperature for 90-360 days to obtain electrolytic manganese residue macroaggregates. The present invention improves the hardening of soil and the pH of the soil by means of the bagasse and effectively accelerates the formation of the electrolytic manganese residue macroaggregates by means of microorganisms and organic matters in the earthworm manure, so that the electrolytic manganese residue is converted into a soil-like substrate, thereby realizing vegetation restoration in manganese mine wastelands and stockpiling yards. The raw materials and method used in the present invention are simple and readily achievable, and the problem of stockpiling of a large amount of electrolytic manganese residue and the problem of environmental pollution caused by the stockpiling of the electrolytic manganese residue can be effectively solved.

Description

A method for promoting soil matrix improvement of electrolytic manganese slag Technical Field

[0001] The invention belongs to the technical field of environmental protection, and particularly relates to a method for improving a substrate by promoting the transformation of electrolytic manganese slag into soil. Background Art

[0002] Electrolytic manganese residue (EMR) is the acid leaching residue produced by the sulfuric acid leaching of manganese metal from rhodochrosite. For every ton of EMR produced, 8 to 10 tons of EMR are discharged. Currently, my country accounts for 98% of the world's total EMR production capacity, discharging approximately 20 million tons of EMR annually, with a cumulative total of over 80 million tons. This vast and relatively dispersed stockpile also results in an overall utilization rate of less than 20%. EMR contains high levels of sulfate, ammonia nitrogen, and manganese, along with a significant amount of soluble pollutants. Long-term storage allows these pollutants to seep into the natural environment, posing a serious threat to the environment, human health, and the economy.

[0003] At present, there are mainly the following ways to treat electrolytic manganese slag as a resource:

[0004] 1. Preparation of building materials: Electrolytic manganese slag has a certain potential cementing activity and can be used as lightweight aggregate, retarder, cementitious material, etc. Manganese slag contains anhydrous calcium sulfate, which has slightly better solubility characteristics than the commonly used dihydrate gypsum in water, and its dissolution rate is slightly lower than that of dihydrate gypsum. Since manganese slag contains SiO2, CaO, Al2O3 and other components, it can be used as the main raw material for making bricks and ceramics, providing a research basis for manganese slag as an admixture to make clay bricks and ceramics. However, the maximum dosage of electrolytic manganese slag is only 5%, and the mass fraction of electrolytic manganese slag added in actual production is 3%. The dosage is relatively small, so it is difficult to put into production for large-scale application and it is difficult to solve the problem of large-scale storage of electrolytic manganese slag.

[0005] 2. Preparation of organic fertilizers: Electrolytic manganese slag is not only rich in nitrogen, but also contains nutrients required by plants such as manganese, potassium, ammonium nitrogen and organic matter. It also has the effects of improving soil, increasing fertilizer efficiency, and enhancing crop disease resistance and lodging resistance, making it a promising research method for the preparation of organic fertilizers. Although the method of using electrolytic manganese waste slag to make fertilizers has long been seen in Chinese and foreign literature, there has been no report of its successful promotion in practice, and there has been no confirmed example in the electrolytic manganese industry.

[0006] 3. Preparation of new materials: Electrolytic manganese slag is used to prepare microcrystalline glass. The prepared microcrystalline glass contains a CaO-Al2O3-SiO2 component system or a CaO-MgO-Al2O3-SiO2 component system. Manganese slag mainly contains SiO2, CaO, MgO, Al2O3 and other material components, which can be used as the basic component of microcrystalline glass. By adding ingredients such as calcium carbonate, quartz sand and magnesium carbonate, they are mixed in proportion and then fired in a furnace to make basic glass. On this basis, a series of processes including post-forming, nucleation, crystallization treatment and annealing are completed to prepare microcrystalline glass. The manganese slag content in this method is large, up to 99%, but due to the high production cost, it is difficult to promote and apply.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to provide a method for improving the matrix of electrolytic manganese slag, which can solve the problem of environmental pollution caused by the storage of large amounts of electrolytic manganese slag by promoting the formation of large agglomerates.

[0009] The present invention provides a method for improving an electrolytic manganese slag matrix, comprising the following steps:

[0010] (1) Taking an electrolytic manganese slag sample, bringing the sample back to the laboratory, air-drying it naturally, removing debris such as gravel, and sieving it for later use to obtain a pretreated sample;

[0011] (2) adding bagasse and earthworm manure to the pretreated sample in step (1) according to the addition ratio, and mixing them uniformly to obtain a mixture;

[0012] (3) adding deionized water to the mixture described in step (2) to wash the residue, and incubating at room temperature to obtain large agglomerates of electrolytic manganese slag.

[0013] In the step (1), the electrolytic manganese slag sample taken from the abandoned mining area is a soil layer of 0 to 50 cm.

[0014] In the step (1), the pretreatment includes removing large impurities, air drying and passing through a 5-15 mesh sieve.

[0015] In the step (2), the proportion of bagasse added is 4-8% of the mass of the pretreated sample; the proportion of earthworm manure added is 4-8% of the mass of the pretreated sample.

[0016] In the step (3), deionized water is added to maintain a water retention rate of 60% to 70%.

[0017] In the step (3), the culture time is 90 to 360 days.

[0018] The principle of the present invention is that electrolytic manganese slag is the acid leaching residue produced by leaching metallic manganese from rhodochrosite with sulfuric acid. The waste residue produced through multiple filter presses is extremely fine particles. Furthermore, after extensive impurity removal, the electrolytic manganese slag still contains iron hydroxide colloids. These colloids make it difficult to completely filter out the moisture in the electrolytic manganese slag, resulting in a relatively high moisture content and hindering the formation of large aggregates. Residual soluble heavy metal ions penetrate the soil layer, reducing the soil organic matter content and limiting the formation of large aggregates in the electrolytic manganese slag. The present invention can effectively improve soil compaction by adding sugarcane bagasse, making the soil looser, and at the same time, can make the soil sufficiently air permeable, making it less likely to generate water accumulation, thereby promoting the formation of large agglomerates of electrolytic manganese slag; the earthworm manure contains a large amount of organic matter and microorganisms, further promoting the formation of large agglomerates of electrolytic manganese slag; the microorganisms and organic molecules in the earthworm manure can provide a poly-binder, promote the bonding between electrolytic manganese slag microaggregates, and form large agglomerates of electrolytic manganese slag; secondly, the polysaccharides secreted by the microorganisms, combined with the physical entanglement of fungal hyphae, can further improve the stability of the large agglomerates of electrolytic manganese slag, and increase the organic matter in the soil.

[0019] The present invention has the following beneficial effects: It uses bagasse to improve soil compaction and pH, utilizes the microorganisms and organic matter in earthworm manure to increase the number and stability of soil aggregates, accelerates the formation of large aggregates of electrolytic manganese slag, and transforms the electrolytic manganese slag into a soil-like matrix, thereby enabling the restoration of vegetation in abandoned manganese mine sites and storage areas. The raw materials and methods employed in the present invention are simple and easy to implement, effectively addressing the problem of large-scale storage of electrolytic manganese slag and the environmental pollution caused by such storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1 is a graph showing the macroagglomerate content of electrolytic manganese slag measured by dry screening method after treatment for 90 days, 180 days, and 360 days in Examples 1, 2, and 3;

[0021] FIG2 is a graph showing the macroagglomerate content of electrolytic manganese slag measured by wet screening method after treatment for 90 days, 180 days, and 360 days in Examples 1, 2, and 3; DETAILED DESCRIPTION

[0022] The invention improves the matrix of electrolytic manganese slag by adding two improvers, namely bagasse and earthworm manure, and converts the electrolytic manganese slag into a soil-like matrix.

[0023] The electrolytic manganese slag sample used in the present invention comes from the Xiaohu tailings pond of the Xiangtan manganese mine; the sugarcane bagasse selected is from a sucrose manufacturer in Nanning, Guangxi, and has a pH of about 7.13; the earthworm manure fertilizer is selected from a farm in Zhejiang, is loose and porous, has a low density, a pH of about 9.00, and contains 76.4% organic matter, 9.72% nitrogen, and 2.36% phosphorus.

[0024] The pH, conductivity, organic matter and macroaggregate content of the treated electrolytic manganese slag were determined.

[0025] Determination of pH, conductivity, and total organic carbon: Weigh 20.00 g of air-dried soil that has passed through a 2 mm sieve and place it in a 250 ml dry Erlenmeyer flask. Add 100 ml of distilled water (water-to-soil ratio 5:1) and shake for 35 minutes. Filter the mixture into a dry Erlenmeyer flask. Collect the supernatant and place it in a 50 ml beaker. Measure pH and conductivity using a pH meter and conductivity meter. Determination of organic carbon in treated samples was performed using the potassium dichromate hydration heating method.

[0026] Aggregates are formed by the entanglement of powder and clay particles through the action of a series of substances such as organic cementing substances and root hyphae. Particles with a size greater than 0.25mm are called macroaggregates, and particles with a size less than 0.25mm are called microaggregates. Macroaggregates are also present in electrolytic manganese slag, but the content is relatively low.

[0027] Determination of the content of large aggregates in electrolytic manganese slag: Dry sieving and wet sieving methods are used for determination. Dry sieving method: Take 100g of air-dried electrolytic manganese slag sample and dry-sieve it through a sieve set with apertures of 2, 1, 0.5, and 0.25mm. After shaking for 15 minutes, collect the sample from the sample sieve and weigh it to the nearest 0.01g. Wet sieving method: Take 100g of air-dried electrolytic manganese slag sample and place it through a 2mm sieve. Then, stack sieves with apertures of 2, 1, 0.5, and 0.25mm in sequence. Add it to a container filled with deionized water and soak it for 1 minute. After shaking for 15 minutes, collect the sample from the sample sieve and weigh it. Then, dry the weighed soil sample at 105℃ and weigh it to the nearest 0.01g.

[0028] Example 1 Changes in the content of large aggregates in electrolytic manganese slag after 90 days of cultivation

[0029] The electrolytic manganese slag sample was pretreated to remove impurities such as gravel, air-dried and passed through a 2mm sieve for later use. 0.5 kg of the sieved sample was taken, sugarcane bagasse and earthworm manure were added in proportion, mixed evenly, and then deionized water was added to maintain a water holding rate of 70%. The sample was cultured at room temperature for 90 days to form large aggregates of electrolytic manganese slag.

[0030] V1B1 group: earthworm manure V120g (4%) and sugarcane bagasse B120g (4%).

[0031] V2B2 group: vermicompost V240 g (8%) and bagasse B240 g (8%).

[0032] Comparative Example 1:

[0033] ck group: other conditions remained unchanged compared to Example 1, except that bagasse and earthworm manure were not added.

[0034] Group B1: other conditions remained unchanged compared to Example 1, except that 20 g (4%) of bagasse B1 was added.

[0035] Group B2: other conditions remained unchanged compared to Example 1, except that 40 g (8%) of bagasse B2 was added.

[0036] Group V1: other conditions remained unchanged compared to Example 1, except that 20 g (4%) of earthworm manure V1 was added.

[0037] Group V2: other conditions remained unchanged compared to Example 1, except that 40 g (8%) of earthworm manure V2 was added.

[0038] The pH, conductivity, organic matter (Table 1) and macroaggregate content (Figures 1 and 2) of the electrolytic manganese slag were measured after 90 days of treatment.

[0039] Table 1 Changes in pH, conductivity, and total organic carbon content of electrolytic manganese slag after 90 days of treatment

[0040] Note: EC: electrical conductivity; TOC: total organic carbon. The values ​​in the table are mean ± standard error. Different lowercase letters in the same column indicate significant differences among different treatments (P<0.05).

[0041] As can be seen from Table 1, after adding sugarcane bagasse alone, the pH of the electrolytic manganese slag decreased significantly and the conductivity increased; after adding vermicompost alone, the organic matter content increased; after adding sugarcane bagasse and vermicompost together, due to the combined effect of sugarcane bagasse and vermicompost, the pH of the electrolytic manganese slag decreased to 8.91 and 8.88, and the organic matter content of the V2B2 group increased significantly.

[0042] As shown in Figure 1, after 90 days of treatment, the content of large aggregates in the electrolytic manganese slag with the combined addition of sugarcane bagasse and earthworm manure increased significantly, from 96.35% to 97.12% (V1B1) and 97.45% (V2B2).

[0043] As can be seen from Figure 2, after 90 days of treatment, the macroaggregate content of the electrolytic manganese slag with sugarcane bagasse added alone was the highest, increasing from 84.1% to 91.05%. The macroaggregate content of the electrolytic manganese slag with vermicompost added alone also increased to 86.35%, indicating that sugarcane bagasse and vermicompost have a certain stabilizing effect on macroaggregates.

[0044] In summary, bagasse and earthworm manure are two amendments that can be used to improve electrolytic manganese slag and transform it into a soil-like matrix.

[0045] Example 2 Changes in the content of large aggregates in electrolytic manganese slag after 180 days of cultivation

[0046] The electrolytic manganese slag sample was pretreated to remove impurities such as gravel, air-dried and passed through a 2mm sieve for later use. 0.5 kg of the sieved sample was taken, sugarcane bagasse and earthworm manure were added in proportion, mixed evenly, and then deionized water was added to maintain a water holding rate of 70%. The sample was cultured at room temperature for 180 days to form large aggregates of electrolytic manganese slag.

[0047] V1B1 group: earthworm manure V120g (4%) and sugarcane bagasse B120g (4%).

[0048] V2B2 group: vermicompost V240 g (8%) and bagasse B240 g (8%).

[0049] Comparative Example 2:

[0050] ck group: other conditions remained unchanged compared to Example 1, except that bagasse and earthworm manure were not added.

[0051] Group B1: other conditions remained unchanged compared to Example 1, except that 20 g (4%) of bagasse B1 was added.

[0052] Group B2: other conditions remained unchanged compared to Example 1, except that 40 g (8%) of bagasse B2 was added.

[0053] Group V1: other conditions remained unchanged compared to Example 1, except that 20 g (4%) of earthworm manure V1 was added.

[0054] Group V2: other conditions remained unchanged compared to Example 1, except that 40 g (8%) of earthworm manure V2 was added.

[0055] The pH, conductivity, organic matter (Table 2) and macroaggregate content (Figures 1 and 2) of the electrolytic manganese slag were measured after 180 days of treatment.

[0056] Table 2 Changes in pH, conductivity, and total organic carbon content of electrolytic manganese slag after 180 days of treatment

[0057] Note: EC: electrical conductivity; TOC: total organic carbon. The values ​​in the table are mean ± standard error. Different lowercase letters in the same column indicate significant differences among different treatments (P<0.05).

[0058] As shown in Table 2, the pH of the electrolytic manganese residue decreased from 8.84 to 8.72 and 8.70 after the addition of bagasse alone, and the conductivity and organic matter content increased. The organic matter content increased after the addition of vermicompost alone. After the combined addition of bagasse and vermicompost, the pH of the electrolytic manganese residue decreased to 8.74 and 8.68 due to the combined effects of bagasse and vermicompost, and the organic matter content of the V2B2 group increased significantly. Compared with the 90-day incubation, the pH of the electrolytic manganese residue did not change much after 180 days of incubation, indicating that bagasse and vermicompost can effectively lower the pH of the electrolytic manganese residue and maintain it stable over a period of time. Compared with the 90-day incubation, the combined addition of bagasse and vermicompost after 180 days of incubation showed a significant increase in organic matter, indicating that bagasse and vermicompost can effectively increase the organic matter content, and the increase in organic matter content becomes more significant with increasing incubation time.

[0059] As can be seen from Figure 1, after 180 days of treatment, the macroaggregate content of the electrolytic manganese slag with the addition of sugarcane bagasse alone increased significantly, from 93.29% to 96.17% (B1) and 97.76% (B2); the macroaggregate content of the electrolytic manganese slag with the addition of vermicompost alone increased from 93.29% to 96.25% (V1) and 96.53% (V2); the macroaggregate content of the electrolytic manganese slag with the combined addition of sugarcane bagasse and vermicompost increased significantly, from 93.29% to 96.43% (V1B1) and 97.33% (V2B2).

[0060] As shown in Figure 2, after 180 days of treatment, the EMM slag macroaggregate content was highest in the treatment with the combined addition of bagasse and vermicompost, increasing from 86.68% to 87.95% (V1B1) and 92.74% (V2B2), indicating that bagasse and vermicompost had a certain stabilizing effect on macroaggregates. Compared to the treatment after 90 days, the macroaggregate content of the EMM slag with the combined addition of bagasse and vermicompost increased significantly, indicating that the combined addition of bagasse and vermicompost has a positive effect on increasing the macroaggregate content of the EMM slag, but its physicochemical and microbial effects require some time to fully manifest.

[0061] Example 3 Changes in the content of large aggregates in electrolytic manganese slag after 360 days of cultivation

[0062] The electrolytic manganese slag sample was pretreated to remove impurities such as gravel, air-dried and passed through a 2mm sieve for later use. 0.5 kg of the sieved sample was taken, sugarcane bagasse and earthworm manure were added in proportion, mixed evenly, and then deionized water was added to maintain a water holding rate of 70%. The sample was cultured at room temperature for 360 days to form large aggregates of electrolytic manganese slag.

[0063] V1B1 group: earthworm manure V120g (4%) and sugarcane bagasse B120g (4%).

[0064] V2B2 group: vermicompost V240 g (8%) and bagasse B240 g (8%).

[0065] Comparative Example 3:

[0066] ck group: other conditions remained unchanged compared to Example 2, except that bagasse and earthworm manure were not added.

[0067] Group B1: other conditions remained unchanged compared to Example 2, except that 20 g (4%) of bagasse B1 was added.

[0068] Group B2: other conditions remained unchanged compared to Example 2, except that 40 g (8%) of bagasse B2 was added.

[0069] Group V1: other conditions remained unchanged compared to Example 2, except that 20 g (4%) of earthworm manure V1 was added.

[0070] Group V2: other conditions remained unchanged compared to Example 2, except that 40 g (8%) of earthworm manure V2 was added.

[0071] The pH, conductivity, organic matter (Table 3) and macroaggregate content (Figures 1 and 2) of the electrolytic manganese slag were measured after 360 days of treatment.

[0072] Table 3 Changes in pH, conductivity, and total organic carbon content of electrolytic manganese slag after 360 days of treatment

[0073] Note: EC: electrical conductivity; TOC: total organic carbon. The values ​​in the table are mean ± standard error. Different lowercase letters in the same column indicate significant differences among different treatments (P<0.05).

[0074] As shown in Table 3, the addition of bagasse alone resulted in a significant decrease in pH, from 8.70 to 8.25 and 8.06, a downward trend in electrical conductivity, and an increase in organic matter content. The addition of vermicompost alone resulted in a decrease in pH and EC, while increasing organic matter content. The combined addition of bagasse and vermicompost achieved the best improvement, with pH dropping to 8.64 and 8.01, and a significant increase in organic matter content. This indicates that the beneficial substances in bagasse and vermicompost gradually and completely react with time. Compared to 180 days, the organic matter content of electrolytic manganese slag after 360 days of incubation showed little change, indicating that bagasse and vermicompost can effectively increase the organic matter content of electrolytic manganese slag and maintain its stability over time.

[0075] As shown in Figure 1, after 360 days of treatment, the macroaggregate content of the electrolytic manganese slag increased from 95.93% to 96.35% (B1) and 96.56% (B2) when sugarcane bagasse was added alone. When vermicompost was added alone, the macroaggregate content of the electrolytic manganese slag increased from 95.93% to 97.17% (V1) and 97.21% (V2). When sugarcane bagasse and vermicompost were added together, the macroaggregate content reached as high as 97.68% (V2B2). Compared to the 180-day incubation period, the macroaggregate content of the electrolytic manganese slag increased, but remained stable across all treatments. The V2B2 group had the highest macroaggregate content, at 97.68%, demonstrating the most significant treatment effect.

[0076] As shown in Figure 2, after 360 days of treatment, the macroaggregate content of electrolytic manganese slag increased from 81.25% to 86.58% (B1) and 88.55% (B2) when sugarcane bagasse was added alone. After adding vermicompost alone, the macroaggregate content of electrolytic manganese slag increased from 81.25% to 93.07% (V1) and 94.25% (V2). After adding sugarcane bagasse and vermicompost together, the macroaggregate content of electrolytic manganese slag increased from 81.25% to 93.65% (V1B1) and 96.07% (V2B2). Among them, the macroaggregate content of the V2B2 group was the highest, indicating the most significant treatment effect. Compared with the 180-day incubation, the macroaggregate content increased significantly after the combined addition of sugarcane bagasse and vermicompost, indicating that the improvement effect of V2B2 was the most obvious after 360 days of treatment.

[0077] Because sugarcane bagasse is neutral, it can effectively reduce the strong alkalinity of electrolytic manganese residue. As the application rate increases, it gradually transforms into a weak alkaline matrix. The increased application of sugarcane bagasse significantly improves the organic matter and EC content of alkaline soils, proving that sugarcane bagasse is a good alternative to traditional organic and inorganic fertilizers under calcareous soil conditions. Soil aggregates are the foundation of soil structure, and the composition of aggregate size is an important indicator of soil quality. The distribution and stability of aggregate size are also important factors in reflecting the quality of soil structure. Vermicompost is light, stable, and has good drainage. Rich in organic matter, vermicompost can effectively increase soil fertility, promote the formation of large aggregates, increase the content of available nutrients and organic matter, and increase soil enzyme activity and microbial populations. The combined application of vermicompost and bagasse can promote the formation and stability of water-stable macroaggregates, significantly increase the average weight diameter of aggregates, and reduce the unstable aggregate index and aggregate destruction rate of aggregates. Therefore, bagasse and vermicompost can effectively improve the physical and chemical properties of electrolytic manganese slag, increase the content of soil macroaggregates, promote the stability of aggregates, and improve soil quality.

Claims

1. A method for promoting the formation of large agglomerates of electrolytic manganese slag, comprising the following steps: (1) taking an electrolytic manganese slag sample and pretreating it to obtain a pretreated sample; (2) adding bagasse and earthworm manure to the pretreated sample in step (1) and mixing them uniformly to obtain a mixture; (3) adding deionized water to the mixture described in step (2), and incubating at room temperature to obtain large agglomerates of electrolytic manganese slag.

2. The method for promoting the formation of large agglomerates of electrolytic manganese slag according to claim 1, characterized in that: In the step (1), the electrolytic manganese slag sample taken from the abandoned mining area is a soil layer of 0 to 50 cm.

3. The method for promoting the formation of large agglomerates of electrolytic manganese slag according to claim 1, characterized in that: In the step (1), the pretreatment includes removing large impurities of gravel, air-drying and passing through a 5-15 mesh sieve for standby use.

4. The method for promoting the formation of large agglomerates of electrolytic manganese slag according to claim 1, characterized in that: In the step (2), the proportion of bagasse added is 4-8% of the mass of the pretreated sample; the proportion of earthworm manure added is 4-8% of the mass of the pretreated sample.

5. The method for promoting the formation of large agglomerates of electrolytic manganese slag according to claim 1, characterized in that: In the step (3), deionized water is added to maintain a water retention rate of 60% to 70%.

6. The method for promoting the formation of large agglomerates of electrolytic manganese slag according to any one of claims 1 to 5, characterized in that: In the step (3), the culture time is 90 to 360 days.

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