Method for preparing heavy metal contaminated soil stabilizer by using electrolytic manganese residue and landfill leachate and application thereof

Abstract

The present invention discloses a method for preparing a heavy metal contaminated soil stabilizer by using electrolytic manganese residue and landfill leachate and its application, belonging to the field of resource utilization of hazardous waste. The preparation process of the method of the present invention is simple, the required raw materials are widely sourced and easily available, and a highly active heavy metal contaminated soil stabilizer is prepared through reasonable batching, roasting enrichment, hydrothermal activation and secondary batching reaction, realizing the full utilization and high-efficient resource utilization of electrolytic manganese residue. The prepared heavy metal contaminated soil stabilizer can significantly reduce the leaching concentration of various heavy metal pollutants in the soil, thereby improving the stability of heavy metal pollutants in the soil.

Description

Technical Field

[0001] The present invention belongs to the field of resource utilization of hazardous waste, and particularly relates to a method for preparing a heavy metal contaminated soil stabilizer by using electrolytic manganese residue and landfill leachate and its application. Background Art

[0002] Electrolytic manganese residue (EMR) is an acid residue formed by filtering after the reaction of manganese ore with sulfuric acid during the production of electrolytic manganese metal. With the rapid development of the electrolytic manganese industry and the increasing market demand, the accumulation amount of electrolytic manganese residue is also continuously increasing. According to research, about 8 tons of electrolytic manganese residue are produced for every 1 ton of electrolytic manganese concentrate produced. These manganese residues contain heavy metal elements such as manganese, lead, zinc, arsenic, etc., and are acidic at the same time, posing a potential threat to the environment. Landfill leachate is wastewater containing high concentrations of organic matter, heavy metal ions and other pollutants generated during the landfill or incineration of garbage. Its composition is complex and it is difficult to treat. If not properly treated, it will cause serious pollution to the environment.

[0003] In the context of the increasing development of industrial and mining activities, the problem of heavy metal contaminated soil is becoming increasingly prominent. Heavy metal ions are difficult to degrade in the soil and are easily enriched through the food chain, posing a threat to human health. Therefore, it is of great significance to develop effective heavy metal contaminated soil remediation technologies. Preparing a heavy metal contaminated soil stabilizer by using electrolytic manganese residue and landfill leachate can realize the resource utilization of waste. This can not only reduce the pollution of electrolytic manganese residue and landfill leachate to the environment, but also reduce the cost of heavy metal contaminated soil remediation. Traditional heavy metal contaminated soil remediation methods mostly use chemical agents or bioremediation technologies, but these methods have problems such as high cost, low efficiency or easy generation of secondary pollution. The heavy metal contaminated soil stabilizer prepared by using electrolytic manganese residue and landfill leachate may have better remediation effects and lower costs. In addition, this method may also provide new ideas and technical support for the remediation of heavy metal contaminated soil.

[0004] With the improvement of environmental protection awareness and the strengthening of environmental protection policies, the environmental protection industry is gradually becoming a new economic growth point. The research on preparing a heavy metal contaminated soil stabilizer by using electrolytic manganese residue and landfill leachate helps to promote the innovation and application of environmental protection technologies and the development of the environmental protection industry. Heavy metal contaminated soil poses a serious threat to human health and environmental safety. The heavy metal contaminated soil stabilizer prepared by using electrolytic manganese residue and landfill leachate can effectively reduce the mobility and bioavailability of heavy metals in the soil, reduce the harm of heavy metals to the environment and human body, and thus ensure human health and environmental safety. Preparing a heavy metal contaminated soil stabilizer by using electrolytic manganese residue and landfill leachate has important research significance and application prospects. This research not only helps to realize the resource utilization of waste and reduce the remediation cost, but also may provide new technical support and solutions for the remediation of heavy metal contaminated soil. Summary of the Invention

[0005] Object of the Invention: The object of the present invention is to provide a method for preparing a heavy metal contaminated soil stabilizer using electrolytic manganese slag and landfill leachate and its application.

[0006] Technical Solution: The present invention provides a method for preparing a heavy metal contaminated soil stabilizer using electrolytic manganese slag and landfill leachate, comprising the following steps:

[0007] (1) Mix ammonium chloride, municipal sludge, and electrolytic manganese slag, and stir evenly to obtain ammonium-loaded manganese slag mud;

[0008] (2) Roast the ammonium manganese slag mud to obtain roasted slag and grind it into roasted powder. The flue gas dust recovered during the roasting process is the recovered dust;

[0009] (3) Mix the recovered dust and straw powder, and stir evenly to obtain a mixed powder;

[0010] (4) Mix landfill leachate and the mixed powder, stir evenly, and then introduce them into a hydrothermal reactor for hydrothermal reaction to obtain a hydrothermally activated slurry;

[0011] (5) Mix fly ash, hydrothermally activated slurry, and roasted powder, stir evenly, and age to obtain a heavy metal contaminated soil stabilizer.

[0012] Further, the mass ratio of ammonium chloride, municipal sludge, and electrolytic manganese slag in step (1) is 0.5~2.5:10~50:100.

[0013] Further, the roasting time in step (2) is 0.5~4.5 hours, and the roasting temperature is 750~1250 °C.

[0014] Further, the mass ratio of the recovered dust and straw powder in step (3) is 2.5~12.5:100.

[0015] Further, the liquid-solid ratio of landfill leachate and the mixed powder in step (4) is 5~25:1 mL / g.

[0016] Further, the temperature of the hydrothermal reaction in step (4) is 120~360 °C, and the hydrothermal time is 0.5~5.5 hours.

[0017] Further, the mass ratio of fly ash, hydrothermally activated slurry, and roasted powder in step (5) is 5~15:30~60:100.

[0018] Further, the aging time in step (5) is 2~12 days.

[0019] The present invention also provides the application of the soil stabilizer prepared by the above method in treating heavy metal pollution.

[0020] Further, the heavy metals include cadmium, mercury, arsenic, and / or lead.

[0021] Reaction mechanism: Mix ammonium chloride, municipal sludge, and electrolytic manganese residue. During the stirring process, the organic matter in the municipal sludge penetrates into the iron, manganese, aluminum, and silicon mineral phases of the electrolytic manganese residue. Roast the manganese residue sludge. During the roasting process, ammonium chloride reacts with the iron, manganese, aluminum, and calcium minerals in the electrolytic manganese residue to generate chloride gas, which enters the flue gas to form dust and is recovered. The water vapor, small molecule organic substances, and carbon-based substances released by the thermal decomposition of the organic matter in the sludge can strengthen the combination of iron, manganese, aluminum, and calcium with chloride ions, and strengthen the release and volatilization of iron, manganese, aluminum, and calcium by increasing the saturated vapor pressure of the chloride and reducing the binding energy. The ammonium ion can combine with the nitrates in the electrolytic manganese residue and sludge and react with the nitrogen oxides formed by the oxidation of nitrogen during the roasting process to form nitrogen gas, making the roasted material more fluffy. During the hydrothermal reaction process, the straw powder will undergo hydrolysis, decarboxylation, dehydration, and condensation reactions, and produce various products. The high molecular polymers such as cellulose, hemicellulose, and lignin in the straw will undergo hydrolysis under hydrothermal conditions to generate oligosaccharides, monosaccharides (such as glucose, xylose, etc.), organic acids, and phenolic compounds. Some organic substances in the straw may undergo decarboxylation reactions to produce carbon dioxide and corresponding hydrocarbon compounds. Some unstable intermediate products or initial reactants may undergo dehydration reactions to form more stable compounds. The monosaccharides and other small molecule compounds produced by hydrolysis may further undergo condensation reactions to form high molecular compounds such as polysaccharides, lignin derivatives, or melanoidins. During the hydrothermal reaction process, the products such as sugars, organic acids, and phenolic compounds generated by the reaction of the straw powder react with the chlorides in the recovered dust to undergo oxidation, reduction, and complexation reactions to form a multi-inorganic precipitate mixture mixed with multiple organic substances. The multivalent iron, manganese, and aluminum and calcium in the mixture form coprecipitation, and the organic matter is loaded on the surface of the coprecipitation or combined with iron, manganese, aluminum, and calcium and doped in the coprecipitation mixture. Mix fly ash, hydrothermal activation slurry, and roasted powder. During the stirring and aging process, the active silicate-aluminate and cations in the fly ash react fully with the multi-inorganic precipitate mixture mixed with multiple organic substances in the hydrothermal activation slurry and the active silicate and aluminoferrite phases in the roasted powder to form a highly active heavy metal contaminated soil stabilizer.

[0022] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages: The preparation process of the method of the present invention is simple, and the required raw materials are widely sourced and easily obtained. By reasonably proportioning, roasting and enriching, hydrothermal activating, and secondary proportioning reactions, a highly active heavy metal contaminated soil stabilizer is prepared, realizing the full utilization and high-efficiency resource utilization of electrolytic manganese residue. The prepared heavy metal contaminated soil stabilizer can significantly reduce the leaching concentration of various heavy metal pollutants in the soil, thereby improving the stability of heavy metal pollutants in the soil. Description of the Drawings

[0023] Figure 1 It is a flow chart of the preparation method of the present invention. Specific embodiments

[0024] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings.

[0025] Municipal sludge: Municipal sludge is taken from the sewage treatment plant in Changshu Southeast Economic Development Zone. Its main chemical components include: 64.17% SiO 2 、13.56% Al 2 O 3 、4.86% Fe 2 O 3 、3.75% P 2 O 5 、2.34% CaO and other components (loss on ignition and other inevitable impurities);

[0026] Electrolytic manganese residue: Electrolytic manganese residue is taken from Guizhou Nengkuang Manganese Industry Group Co., Ltd. It mainly includes 23.52% SO 3 、13.17% SiO 2 、15.21% CaO、13.09% Fe 2 O 3 、6.82% Al 2 O 3 、10.21% MnO、2.96% K 2 O、1.55% MgO、0.86% TiO 2 and other components (inevitable impurities and loss on ignition);

[0027] Landfill leachate: The original landfill leachate is taken from Zhuji Sanfeng Environmental Energy Co., Ltd. The COD mass concentration of this batch of concentrated landfill leachate is 3639 mg / L, the total phosphorus concentration is 294 mg / L, and the ammonia nitrogen concentration is 1062 mg / L. 500 mg of mercury pollutants are dissolved in 1 L of the original landfill leachate to obtain the test landfill leachate;

[0028] Fly ash: From Taicang Power Plant of Huaneng International Power Co., Ltd., it mainly includes 43.21% SiO 2 、27.08% Al 2 O 3 、15.62% Fe 2 O 3 、6.58% CaO、3.42% TiO 2 、1.43% SO 3 、1.04% K 2 O、0.63% Na 2 O and other components (inevitable impurities and loss on ignition);

[0029] Straw: Shaanxi Jinhe Agricultural Technology Co., Ltd., variety: wheat straw powder, brand: Shanjinhe.

[0030] Example 1 Influence of the mass ratio of ammonium chloride, municipal sludge, and electrolytic manganese slag on the performance of the heavy metal contaminated soil stabilizer prepared

[0031] Mix ammonium chloride, municipal sludge, and electrolytic manganese slag according to the mass ratios of 0.2:10:100, 0.3:10:100, 0.4:10:100, 0.5:4:100, 0.5:6:100, 0.5:8:100, 0.5:10:100, 1.5:10:100, 2.5:10:100, 0.5:30:100, 1.5:30:100, 2.5:30:100, 0.5:50:100, 1.5:50:100, 2.5:50:100, 2.5:55:100, 2.5:60:100, 2.5:65:100, 2.75:50:100, 3:50:100, 3.25:50:100, stir evenly to obtain ammonium-loaded manganese slag sludge. Roast the ammonium manganese slag sludge to obtain roasted slag, and the flue gas dust recovered during the roasting process is the recovered dust, where the roasting time is 0.5 hours and the roasting temperature is 750 °C. Mix the recovered dust and straw powder according to the mass ratio of 2.5:100, stir evenly to obtain a mixed powder. Mix the landfill leachate and the mixed powder according to the liquid-solid ratio of 5:1 mL / g, stir evenly, and then introduce it into a hydrothermal reactor for hydrothermal reaction to obtain a hydrothermally activated slurry, where the temperature of the hydrothermal reaction is 120 °C and the hydrothermal time is 0.5 hours. Grind the roasted slag into powder to obtain roasted powder, and mix fly ash, hydrothermally activated slurry, and roasted powder according to the mass ratio of 5:30:100, stir evenly, and age for 2 days to obtain a heavy metal contaminated soil stabilizer.

[0032] Preparation of heavy metal contaminated soil: Weigh 1 kg of uncontaminated soil sample, then add 200 mg of cadmium, 200 mg of mercury, 500 mg of arsenic, and 500 mg of lead to the soil sample, add water to the soil according to the liquid-solid ratio of 1:1 ml / mg, stir evenly, and air-dry naturally after aging for 24 hours to obtain the tested heavy metal contaminated soil sample.

[0033] Stabilization treatment of heavy metal contaminated soil: Weigh 50 g of the tested heavy metal contaminated soil sample and 5 g of the high-efficiency heavy metal stabilizer and place them in a 250 mL beaker respectively. Add 55 mL of water to the beaker according to the liquid-solid ratio of 1:1 ml / mg, stir evenly, seal the beaker mouth with perforated plastic wrap, and semi-seal and cure for 28 d. After the curing is completed, dry the nine groups of samples at a constant temperature, pass through a 200-mesh sieve, and reserve for use.

[0034] Leaching test, heavy metal ion concentration detection and heavy metal stabilization rate calculation: Toxicity leaching tests were carried out on heavy metal contaminated soil and soil samples after stabilization treatment in accordance with the "Solid Waste - Extraction Procedure for Toxicity Characteristics - Sulfuric Acid and Nitric Acid Method" (HJ / T 299 - 2007). The concentrations of two pollutants, lead and cadmium, in the leachate were determined in accordance with the "Water Quality - Determination of 32 Elements - Inductively Coupled Plasma Optical Emission Spectrometry" (HJ 776 - 2015); the concentrations of two pollutants, arsenic and mercury, in the leachate were determined in accordance with the "Water Quality - Determination of Mercury, Arsenic, Selenium, Bismuth and Antimony - Atomic Fluorescence Spectrometry" (HJ 694 - 2014). The stabilization efficiency of heavy metal pollutant M (M: arsenic, cadmium, lead, mercury) was calculated according to the following formula, where is the heavy metal pollutant stabilization efficiency, is the concentration of heavy metal M in the leachate of heavy metal contaminated soil (mg / L), is the concentration of heavy metal M in the leachate after stabilization treatment (mg / L). The test results are shown in Table 1.

[0035]

[0036] Table 1 Influence of mass ratios of ammonium chloride, municipal sludge, and electrolytic manganese slag on the performance of heavy metal contaminated soil stabilizers prepared

[0037]

[0038] As can be seen from Table 1, when the mass ratio of ammonium chloride, municipal sludge, and electrolytic manganese slag is less than 0.5:10:100 (as in Table 1, when the mass ratio of ammonium chloride, municipal sludge, and electrolytic manganese slag = 0.5:8:100, 0.5:6:100, 0.5:4:100, 0.4:10:100, 0.3:10:100, 0.2:10:100 and lower ratios not listed in Table 1), the usage amounts of ammonium chloride and municipal sludge are small, and the reaction of ammonium chloride, municipal sludge, and electrolytic manganese slag is insufficient during the subsequent roasting process, resulting in a significant decrease in the stabilization rates of cadmium, mercury, arsenic, and lead as the mass ratio of ammonium chloride, municipal sludge, and electrolytic manganese slag decreases; when the mass ratio of ammonium chloride, municipal sludge, and electrolytic manganese slag is equal to 0.5 - 2.5:10 - 50:100 (as in Table 1, when the mass ratio of ammonium chloride, municipal sludge, and electrolytic manganese slag = 0.5:10:100, 1.5:10:100, 2.5:10:100, 0.5:30:100, 1.5:30:100, 2.5:30:100, 0.5:50:100, 1.5:50:100, 2.5:50:100), when mixing ammonium chloride, municipal sludge, and electrolytic manganese slag, the organic matter in the municipal sludge penetrates into the iron, manganese, aluminum, and silicon mineral phases in the electrolytic manganese slag during the stirring process. Roasting the manganese slag sludge, during the roasting process, ammonium chloride reacts with the iron, manganese, aluminum, and calcium minerals in the electrolytic manganese slag to generate chloride gases that enter the flue gas to form dust for recovery. The water vapor, small molecule organic substances, and carbon-based substances released by the thermal decomposition of the organic matter in the sludge can strengthen the combination of iron, manganese, aluminum, and calcium with chloride ions, and strengthen the release and volatilization of iron, manganese, aluminum, and calcium by increasing the saturated vapor pressure of the chloride and reducing the binding energy. And the ammonium ion can combine with the nitrates in the electrolytic manganese slag and sludge and react with the nitrogen oxides formed by the oxidation of nitrogen during the roasting process to form nitrogen gas, and make the roasted material more fluffy. Finally, the stabilization rates of heavy metals cadmium, mercury, arsenic, and lead achieved by the soil stabilizer are respectively greater than 87%, 89%, 92%, and 90%. When the mass ratio of ammonium chloride, municipal sludge, and electrolytic manganese slag is greater than 2.5:50:100 (as in Table 1, when the mass ratio of ammonium chloride, municipal sludge, and electrolytic manganese slag = 2.5:55:100, 2.5:60:100, 2.5:65:100, 2.75:50:100, 3:50:100, 3.25:50:100 and higher ratios not listed in Table 1), the addition of ammonium chloride and municipal sludge is excessive, and the reaction of the materials is unbalanced during the roasting process, resulting in a decrease in the stabilization rates of heavy metals cadmium, mercury, arsenic, and lead as the mass ratio of ammonium chloride, municipal sludge, and electrolytic manganese slag further increases. Therefore, generally speaking, considering the combination of benefits and costs, when the mass ratio of ammonium chloride, municipal sludge, and electrolytic manganese slag is equal to 0.5 - 2.5:10 - 50:100, it is most beneficial to improve the heavy metal stabilization performance of the prepared stabilizer.

[0039] Example 2 Influence of the mass ratio of recycled dust to straw powder on the performance of the heavy metal contaminated soil stabilizer prepared

[0040] Mix ammonium chloride, municipal sludge, and electrolytic manganese slag in a mass ratio of 2.5:50:100, stir evenly to obtain ammonium-loaded manganese slag sludge. Roast the ammonium-manganese slag sludge to obtain roasted slag. The flue gas dust recovered during the roasting process is recycled dust, where the roasting time is 2.5 hours and the roasting temperature is 1000 °C. Mix the recycled dust and straw powder in mass ratios of 1:100, 1.5:100, 2:100, 2.5:100, 7.5:100, 12.5:100, 15:100, 17.5:100, 20:100, stir evenly to obtain a mixed powder. Mix the landfill leachate and the mixed powder in a liquid-solid ratio of 15:1 mL / g, stir evenly, and then introduce it into a hydrothermal autoclave for hydrothermal reaction to obtain hydrothermally activated pulp, where the temperature of the hydrothermal reaction is 240 °C and the hydrothermal time is 3 hours. Grind the roasted slag into powder to obtain roasted powder. Mix fly ash, hydrothermally activated pulp, and roasted powder in a mass ratio of 10:45:100, stir evenly, and age for 7 days to obtain a heavy metal contaminated soil stabilizer.

[0041] The preparation of heavy metal contaminated soil, the stabilization treatment of heavy metal contaminated soil, the leaching test, the detection of heavy metal ion concentration, and the calculation of heavy metal stabilization rate are the same as those in Example 1.

[0042] Table 2 Influence of the mass ratio of recycled dust to straw powder on the performance of the heavy metal contaminated soil stabilizer prepared

[0043]

[0044] As can be seen from Table 2, when the mass ratio of recycled dust to straw powder is less than 2.5:100 (as in Table 2, the mass ratio of recycled dust to straw powder = 2:100, 1.5:100, 1:100 and lower ratios not listed in Table 2), less recycled dust is added, and the reaction between recycled dust and straw powder during the hydrothermal process is insufficient, resulting in a significant decrease in the stabilization rates of cadmium, mercury, arsenic, and lead with the decrease in the mass ratio of recycled dust to straw powder; when the mass ratio of recycled dust to straw powder is equal to 2.5 - 12.5:100 (as in Table 2, the mass ratio of recycled dust to straw powder = 2.5:100, 7.5:100, 12.5:100), during the hydrothermal reaction process, the straw powder will undergo reactions such as hydrolysis, decarboxylation, dehydration, and condensation, and produce various products. High molecular polymers such as cellulose, hemicellulose, and lignin in the straw will undergo hydrolysis under hydrothermal conditions to generate oligosaccharides, monosaccharides (such as glucose, xylose, etc.), organic acids, and phenolic compounds. Some organic substances in the straw may undergo decarboxylation reactions to produce carbon dioxide and corresponding hydrocarbon compounds. Some unstable intermediate products or initial reactants may undergo dehydration reactions to form more stable compounds. The monosaccharides and other small molecule compounds produced by hydrolysis may further undergo condensation reactions to form high molecular compounds such as polysaccharides, lignin derivatives, or melanoidins. During the hydrothermal reaction process, products such as sugars, organic acids, and phenolic compounds generated by the reaction of straw powder react with chlorides in the recycled dust to undergo oxidation, reduction, and complexation reactions, forming a multi - organic - mixed multi - inorganic precipitation mixture. Multivalent iron, manganese in the mixture form coprecipitation with aluminum and calcium, and the organic matter is loaded on the surface of the coprecipitation or combines with iron, manganese, aluminum, and calcium, doping in the coprecipitation mixture. Finally, the stabilization rates of heavy metals cadmium, mercury, arsenic, and lead achieved by the soil stabilizer are respectively greater than 93%, 94%, 95%, and 95%. When the mass ratio of recycled dust to straw powder is greater than 12.5:100 (as in Table 2, the mass ratio of recycled dust to straw powder = 15:100, 17.5:100, 20:100 and higher ratios not listed in Table 2), excessive recycled dust is added, and the material reaction is unbalanced during the hydrothermal reaction process, resulting in a decrease in the stabilization rates of heavy metals cadmium, mercury, arsenic, and lead with the further increase in the mass ratio of recycled dust to straw powder. Therefore, generally speaking, considering both benefits and costs, when the mass ratio of recycled dust to straw powder is equal to 2.5 - 12.5:100, it is most beneficial to improve the heavy metal stabilization performance of the prepared stabilizer.

[0045] Example 3 Influence of the mass ratio of fly ash, hydrothermal activation slurry, and calcined powder on the performance of the heavy - metal - contaminated soil stabilizer prepared

[0046] Mix ammonium chloride, municipal sludge, and electrolytic manganese slag in a mass ratio of 2.5:50:100, stir evenly to obtain ammonium-loaded manganese slag sludge. Roast the ammonium-manganese slag sludge to obtain roasted slag, and the flue gas dust recovered during the roasting process is the recovered dust, where the roasting time is 4.5 hours and the roasting temperature is 1250 °C. Mix the recovered dust and straw powder in a mass ratio of 12.5:100, stir evenly to obtain a mixed powder. Mix the landfill leachate and the mixed powder in a liquid-solid ratio of 25:1 mL / g, stir evenly, and then introduce it into a hydrothermal reactor for hydrothermal reaction to obtain a hydrothermally activated slurry, where the temperature of the hydrothermal reaction is 360 °C and the hydrothermal time is 5.5 hours. Grind the roasted slag into powder to obtain roasted powder, and mix fly ash, hydrothermally activated slurry, and roasted powder in mass ratios of 2:30:100, 3:30:100, 4:30:100, 5:22.5:100, 5:25:100, 5:27.5:100, 5:30:100, 10:30:100, 15:30:100, 5:45:100, 10:45:100, 15:45:100, 5:60:100, 10:60:100, 15:60:100, 15:65:100, 15:70:100, 15:75:100, 17.5:60:100, 20:60:100, 22.5:60:100, stir evenly, and age for 12 days to obtain a heavy metal contaminated soil stabilizer.

[0047] The preparation of heavy metal contaminated soil, the stabilization treatment of heavy metal contaminated soil, the leaching test, the detection of heavy metal ion concentration, and the calculation of heavy metal stabilization rate are the same as those in Example 1.

[0048] Table 3 Influence of the mass ratio of fly ash, hydrothermally activated slurry, and roasted powder on the performance of the prepared heavy metal contaminated soil stabilizer

[0049]

[0050] As can be seen from Table 3, when the mass ratio of fly ash, hydrothermally activated slurry, and calcined powder is less than 5:30:100 (as in Table 3, when the mass ratio of fly ash, hydrothermally activated slurry, and calcined powder = 5:27.5:100, 5:25:100, 5:22.5:100, 4:30:100, 3:30:100, 2:30:100 and lower ratios not listed in Table 3), the addition of fly ash and hydrothermally activated slurry is less, and the reaction of fly ash, hydrothermally activated slurry, and calcined powder during the aging process is insufficient, resulting in a significant decrease in the stabilization rates of cadmium, mercury, arsenic, and lead as the mass ratio of recycled dust and straw powder decreases; when the mass ratio of fly ash, hydrothermally activated slurry, and calcined powder is equal to 5 - 15:30 - 60:100 (as in Table 3, when the mass ratio of fly ash, hydrothermally activated slurry, and calcined powder = 5:30:100, 10:30:100, 15:30:100, 5:45:100, 10:45:100, 15:45:100, 5:60:100, 10:60:100, 15:60:100), the mixed fly ash, hydrothermally activated slurry, and calcined powder are fully reacted during the stirring and aging process, where the active silicate and aluminates and cations in fly ash are mixed with the multi - organic - mixed multi - inorganic precipitation mixture in the hydrothermally activated slurry and the active silicate and aluminosilicate phases in the calcined powder to form a highly active heavy - metal - contaminated soil stabilizer. Finally, the stabilization rates of heavy metals cadmium, mercury, arsenic, and lead achieved by the soil stabilizer are respectively greater than 96%, 98%, 98%, and 97%. When the mass ratio of fly ash, hydrothermally activated slurry, and calcined powder is greater than 15:60:100 (as in Table 3, when the mass ratio of fly ash, hydrothermally activated slurry, and calcined powder = 15:65:100, 15:70:100, 15:75:100, 17.5:60:100, 20:60:100, 22.5:60:100 and higher ratios not listed in Table 3), the addition of fly ash and hydrothermally activated slurry is excessive, and the material reaction is unbalanced during the aging process, resulting in a decrease in the stabilization rates of heavy metals cadmium, mercury, arsenic, and lead as the mass ratio of fly ash, hydrothermally activated slurry, and calcined powder further increases. Therefore, generally speaking, considering both benefits and costs, when the mass ratio of fly ash, hydrothermally activated slurry, and calcined powder is equal to 5 - 15:30 - 60:100, it is most beneficial to improve the heavy - metal stabilization performance of the prepared stabilizer.

[0051] Comparative Example 1 Influence of Different Processes on the Performance of Prepared Heavy - Metal - Contaminated Soil Stabilizer

[0052] Process of the present invention: Mix ammonium chloride, municipal sludge, and electrolytic manganese slag in a mass ratio of 2.5:50:100, stir evenly to obtain ammonium-loaded manganese slag mud. Roast the ammonium-loaded manganese slag mud to obtain roasted slag, and the flue gas dust recovered during the roasting process is the recovered dust, where the roasting time is 4.5 hours and the roasting temperature is 1250 °C. Mix the recovered dust and straw powder in a mass ratio of 12.5:100, stir evenly to obtain a mixed powder. Mix landfill leachate and the mixed powder in a liquid-solid ratio of 25:1 mL / g, stir evenly, and then introduce it into a hydrothermal reactor for hydrothermal reaction to obtain hydrothermally activated slurry, where the temperature of the hydrothermal reaction is 360 °C and the hydrothermal time is 5.5 hours. Grind the roasted slag into powder to obtain roasted powder, mix fly ash, hydrothermally activated slurry, and roasted powder in a mass ratio of 15:60:100, stir evenly, and age for 12 days to obtain a heavy metal contaminated soil stabilizer.

[0053] Comparative process 1: Mix ammonium chloride, municipal sludge, and electrolytic manganese slag in a mass ratio of 2.5:50:100, stir evenly to obtain ammonium-loaded manganese slag mud. Roast the ammonium-loaded manganese slag mud to obtain roasted slag, and the flue gas dust recovered during the roasting process is the recovered dust, where the roasting time is 4.5 hours and the roasting temperature is 1250 °C. Mix the recovered dust and straw powder in a mass ratio of 12.5:100, stir evenly to obtain a mixed powder. Mix water and the mixed powder in a liquid-solid ratio of 25:1 mL / g, stir evenly, and then introduce it into a hydrothermal reactor for hydrothermal reaction to obtain hydrothermally activated slurry, where the temperature of the hydrothermal reaction is 360 °C and the hydrothermal time is 5.5 hours. Grind the roasted slag into powder to obtain roasted powder, mix fly ash, hydrothermally activated slurry, and roasted powder in a mass ratio of 15:60:100, stir evenly, and age for 12 days to obtain a heavy metal contaminated soil stabilizer.

[0054] Comparative process 2: Mix ammonium chloride, municipal sludge, and electrolytic manganese slag in a mass ratio of 2.5:50:100, stir evenly to obtain ammonium-loaded manganese slag mud. Roast the ammonium-loaded manganese slag mud to obtain roasted slag, and the flue gas dust recovered during the roasting process is the recovered dust, where the roasting time is 4.5 hours and the roasting temperature is 1250 °C. Mix landfill leachate and the recovered dust in a liquid-solid ratio of 25:1 mL / g, stir evenly, and then introduce it into a hydrothermal reactor for hydrothermal reaction to obtain hydrothermally activated slurry, where the temperature of the hydrothermal reaction is 360 °C and the hydrothermal time is 5.5 hours. Grind the roasted slag into powder to obtain roasted powder, mix fly ash, hydrothermally activated slurry, and roasted powder in a mass ratio of 15:60:100, stir evenly, and age for 12 days to obtain a heavy metal contaminated soil stabilizer.

[0055] Comparative process 3: Mix ammonium chloride, municipal sludge, and electrolytic manganese slag in a mass ratio of 2.5:50:100, stir evenly to obtain ammonium-loaded manganese slag sludge. Roast the ammonium-manganese slag sludge to obtain roasted slag, and the flue gas dust recovered during the roasting process is the recovered dust, where the roasting time is 4.5 hours and the roasting temperature is 1250 °C. Mix the recovered dust and straw powder in a mass ratio of 12.5:100, stir evenly to obtain a mixed powder. Mix the landfill leachate and the mixed powder in a liquid-solid ratio of 25:1 mL / g, stir evenly, and then introduce it into a hydrothermal reactor for hydrothermal reaction to obtain a hydrothermally activated slurry, where the temperature of the hydrothermal reaction is 360 °C and the hydrothermal time is 5.5 hours. Grind the roasted slag into powder to obtain roasted powder, mix the hydrothermally activated slurry and the roasted powder in a mass ratio of 60:100, stir evenly, and age for 12 days to obtain a heavy metal contaminated soil stabilizer.

[0056] The preparation of heavy metal contaminated soil, the stabilization treatment of heavy metal contaminated soil, the leaching test, the detection of heavy metal ion concentration, and the calculation of heavy metal stabilization rate are the same as those in Example 1.

[0057] Table 4 Effects of different processes on the performance of the heavy metal contaminated soil stabilizer prepared

[0058]

[0059] As can be seen from Table 4, the heavy metal stabilization rates achieved by the heavy metal contaminated soil stabilizer prepared by the process of the present invention are significantly higher than those of the heavy metal contaminated soil stabilizers prepared by Comparative Process 1, Comparative Process 2, and Comparative Process 3.

Claims

1. A method for preparing a heavy metal contaminated soil stabilizer using electrolytic manganese slag and landfill leachate, characterized in that: The following steps are involved: (1) ammonium chloride, municipal sludge and electrolytic manganese slag are mixed and stirred evenly to obtain ammonium-loaded manganese slag sludge; The mass ratio of ammonium chloride, municipal sludge and electrolytic manganese slag is 0.5-2.5:10-50:100; (2) roasting the ammonium-loaded manganese slag mud to obtain roasting slag and grinding it into roasting powder, and the flue gas dust recovered during the roasting process is the recovered dust; (3) Mixing the recycled dust and straw powder and stirring them evenly to obtain mixed powder; The mass ratio of the recycled dust to the straw powder is 2.5-12.5:100; (4) mixing the landfill leachate and the mixed powder, stirring them evenly, and then introducing them into a hydrothermal kettle for hydrothermal reaction to obtain a hydrothermal activated slurry; (5) mixing fly ash, hydrothermal activated slurry and roasted powder, stirring evenly, and aging to obtain a heavy metal contaminated soil stabilizer; The mass ratio of the fly ash, hydrothermal activated slurry and roasted powder is 5-15:30-60:

100.

2. The method according to claim 1, characterized in that The calcination time in step (2) is 0.5 to 4.5 hours, and the calcination temperature is 750 to 1250°C.

3. The method according to claim 1, characterized in that The liquid-to-solid ratio of the landfill leachate and the mixed powder in step (4) is 5-25:1 mL / g.

4. The method according to claim 1, characterized in that: The temperature of the hydrothermal reaction in step (4) is 120-360° C., and the hydrothermal time is 0.5-5.5 hours.

5. The method according to claim 1, characterized in that The aging time described in step (5) is 2 to 12 days.

6. Use of the soil stabilizer prepared by the method according to any one of claims 1 to 5 in treating heavy metal pollution.

7. The use according to claim 6, characterized in that: The heavy metals include cadmium, mercury, arsenic and / or lead.

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