Method for preparing heavy metal contaminated soil stabilizer from electrolytic manganese residues and landfill leachate and application of heavy metal contaminated soil stabilizer

Abstract

The invention discloses a method for preparing a heavy metal contaminated soil stabilizer from electrolytic manganese residues and landfill leachate and application of the heavy metal contaminated soil stabilizer, and belongs to the field of hazardous waste resource utilization. According to the method, the preparation process is simple, the needed raw materials are wide in source and easy to obtain, the high-activity heavy metal contaminated soil stabilizer is prepared through reasonable burdening, roasting enrichment, hydrothermal activation and secondary burdening reaction, and full utilization and efficient recycling of the electrolytic manganese residues are achieved. The prepared heavy metal contaminated soil stabilizer can remarkably reduce the leaching concentration of various heavy metal pollutants in soil, so that the stability of the heavy metal pollutants in the soil is improved.

Description

Technical Field

[0001] The invention belongs to the field of resource utilization of hazardous wastes, and in particular relates to a method for preparing a heavy metal contaminated soil stabilizer by utilizing electrolytic manganese slag and garbage leachate, and application thereof. Background Art

[0002] Electrolytic manganese slag (EMR) is the acid slag formed by filtering manganese ore after reacting with sulfuric acid during the production of electrolytic manganese metal. With the rapid development of the electrolytic manganese industry and the increase in market demand, the accumulation of electrolytic manganese slag is also increasing. According to research, about 8 tons of electrolytic manganese slag are produced for every ton of electrolytic manganese concentrate. These manganese slags contain heavy metal elements such as manganese, lead, zinc, arsenic, etc., and are acidic, posing a potential threat to the environment. Leachate is wastewater containing high concentrations of organic matter, heavy metal ions and other pollutants generated during landfill or incineration. Its composition is complex and difficult to handle. If not properly handled, it will cause serious pollution to the environment.

[0003] Against the background of the growing development of industrial and mining activities, the problem of heavy metal contaminated soil has become increasingly prominent. Heavy metal ions are difficult to degrade in 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 technology. The preparation of heavy metal contaminated soil stabilizers using electrolytic manganese slag and landfill leachate can realize the resource utilization of waste. This can not only reduce the pollution of electrolytic manganese slag 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 biological remediation technologies, but these methods have problems such as high cost, low efficiency or easy to produce secondary pollution. Heavy metal contaminated soil stabilizers prepared using electrolytic manganese slag 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 awareness and the strengthening of environmental protection policies, the environmental protection industry is gradually becoming a new economic growth point. The research on the preparation of heavy metal contaminated soil stabilizers using electrolytic manganese slag and landfill leachate will help promote the innovation and application of environmental protection technologies and promote 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 using electrolytic manganese slag 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 protect human health and environmental safety. The preparation of heavy metal contaminated soil stabilizers using electrolytic manganese slag 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 cost of remediation, but also may provide new technical support and solutions for the remediation of heavy metal contaminated soil. Summary of the invention

[0005] Purpose of the invention: The purpose 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: (1) ammonium chloride, municipal sludge and electrolytic manganese slag are mixed and stirred evenly to obtain ammonium-loaded manganese slag sludge; (2) roasting the ammonium manganese sludge to obtain roasting slag and grinding it into roasting powder, and the flue gas dust recovered in the roasting process is the recovered dust; (3) Mixing the recycled dust and straw powder and stirring them evenly to obtain mixed powder; (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) The fly ash, hydrothermal activated slurry and roasted powder are mixed, stirred evenly, and aged to obtain a heavy metal contaminated soil stabilizer.

[0007] Furthermore, the mass ratio of ammonium chloride, municipal sludge and electrolytic manganese slag in step (1) is 0.5-2.5:10-50:100.

[0008] Furthermore, the calcination time in step (2) is 0.5 to 4.5 hours, and the calcination temperature is 750 to 1250°C.

[0009] Furthermore, the mass ratio of the recovered dust to the straw powder in step (3) is 2.5-12.5:100.

[0010] Furthermore, the liquid-to-solid ratio of the landfill leachate and the mixed powder in step (4) is 5-25:1 mL / g.

[0011] Furthermore, the temperature of the hydrothermal reaction in step (4) is 120-360° C., and the hydrothermal time is 0.5-5.5 hours.

[0012] Furthermore, the mass ratio of the fly ash, hydrothermal activated slurry and roasted powder in step (5) is 5-15:30-60:100.

[0013] Furthermore, the aging time in step (5) is 2 to 12 days.

[0014] The present invention also provides the use of the soil stabilizer prepared by the method in treating heavy metal pollution.

[0015] Furthermore, the heavy metals include cadmium, mercury, arsenic and / or lead.

[0016] Reaction mechanism: ammonium chloride, municipal sludge and electrolytic manganese slag are mixed. During the stirring process, the organic matter in the municipal sludge penetrates into the iron, manganese, aluminum and silicon mineral phases in the electrolytic manganese slag. The manganese slag sludge is roasted. During the roasting process, ammonium chloride reacts with the iron, manganese, aluminum and calcium minerals in the electrolytic manganese slag to generate chloride gas, which enters the flue gas to form dust for recovery. The water vapor and small molecular organic matter released by the pyrolysis of organic matter in the sludge and the carbon-based substances formed 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 chloride and reducing the binding energy. The ammonium ions can react with the nitrates in the electrolytic manganese slag and sludge and the nitrogen oxides formed by the oxidation of nitrogen during the roasting process to form nitrogen, and make the roasting material more fluffy. During the hydrothermal reaction, the straw powder will undergo hydrolysis, decarboxylation, dehydration and condensation reactions, and produce a variety of products. High molecular polymers such as cellulose, hemicellulose and lignin in straw will be hydrolyzed under hydrothermal conditions to produce oligosaccharides, monosaccharides (such as glucose, xylose, etc.), organic acids and phenolic compounds. Some organic matter in straw may undergo decarboxylation reaction to produce carbon dioxide and corresponding hydrocarbon compounds. Some unstable intermediates or initial reactants may undergo dehydration reaction to produce more stable compounds. Monosaccharides and other small molecular compounds produced by hydrolysis may further undergo condensation reaction to produce polysaccharides, lignin derivatives or melanoidins and other high molecular compounds. During the hydrothermal reaction process, the products such as sugars, organic acids, phenolic compounds generated by the reaction of straw powder undergo oxidation, reduction and complexation reactions with chlorides in the recovered dust to form a multi-organic inorganic precipitation mixture mixed with multiple organic matter. The multivalent iron, manganese, aluminum and calcium in the mixture form a co-precipitation, and the organic matter is loaded on the co-precipitation surface or combined with iron, manganese, aluminum and calcium, and doped in the co-precipitation mixture. Fly ash, hydrothermal activated slurry and calcined powder are mixed. During the stirring and aging process, the active aluminosilicates and cations in the fly ash fully react with the multi-organic inorganic precipitation mixture mixed with multi-organic matter in the hydrothermal activated slurry and the active silicates and aluminoferrites in the calcined powder to form a highly active heavy metal contaminated soil stabilizer.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: the method of the present invention has a simple preparation process, the required raw materials are widely available and easily available, and a high-activity heavy metal contaminated soil stabilizer is prepared by reasonable batching, roasting enrichment, hydrothermal activation and secondary batching reaction, thereby achieving full utilization and efficient resource utilization of electrolytic manganese slag. 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a flow chart of the preparation method of the present invention. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0020] Municipal sludge: Municipal sludge was taken from the sewage treatment plant in Changshu Southeast Economic Development Zone. The main chemical components include: 64.17% SiO2, 13.56% Al2O3, 4.86% Fe2O3, 3.75% P2O5, 2.34% CaO and other components (loss on ignition and other inevitable impurities); Electrolytic manganese slag: Electrolytic manganese slag is taken from Guizhou Energy Mining Manganese Industry Group Co., Ltd., mainly including 23.52% SO3, 13.17% SiO2, 15.21% CaO, 13.09% Fe2O3, 6.82% Al2O3, 10.21% MnO, 2.96% K2O, 1.55% MgO, 0.86% TiO2 and other components (unavoidable impurities and ignition loss); Landfill leachate: The original landfill leachate was obtained from Zhuji Sanfeng Environmental Protection Energy Co., Ltd. The COD mass concentration of this batch of concentrated landfill leachate was 3639 mg / L, the total phosphorus concentration was 294 mg / L, and the ammonia nitrogen concentration was 1062 mg / L. 500 mg of mercury pollutant was dissolved in 1 L of landfill leachate to obtain the landfill leachate for the test; Fly ash: from Taicang Power Plant of Huaneng Power International Co., Ltd., mainly including 43.21% SiO2, 27.08% Al2O3, 15.62% Fe2O3, 6.58% CaO, 3.42% TiO2, 1.43% SO3, 1.04% K2O, 0.63% Na2O and other components (unavoidable impurities and ignition loss); Straw: Shaanxi Jinhe Agricultural Technology Co., Ltd., Type: wheat straw powder, Brand: Shaanxi Jinhe.

[0021] Example 1 Effect of the mass ratio of ammonium chloride, municipal sludge and electrolytic manganese slag on the performance of the prepared heavy metal contaminated soil stabilizer According to the mass ratio 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 ammonium chloride, municipal sludge, electrolytic manganese slag, stir evenly to obtain ammonium manganese slag sludge. The ammonium manganese sludge is roasted to obtain roasted slag, and the flue gas dust recovered in the roasting process is the recovered dust, wherein the roasting time is 0.5 hours, and the roasting temperature is 750°C. The recovered dust and straw powder are mixed in a mass ratio of 2.5:100, stirred evenly, and a mixed powder is obtained. The landfill leachate and the mixed powder were mixed at a liquid-solid ratio of 5:1 mL / g, stirred evenly, and then introduced into a hydrothermal kettle for hydrothermal reaction to obtain a hydrothermal activated slurry, wherein the temperature of the hydrothermal reaction was 120°C and the hydrothermal time was 0.5 hours. The roasted slag was ground into powder to obtain roasted powder, and fly ash, hydrothermal activated slurry, and roasted powder were mixed at a mass ratio of 5:30:100, stirred evenly, and aged for 2 days to obtain a heavy metal contaminated soil stabilizer.

[0022] Preparation of heavy metal contaminated soil: Weigh 1 kg of soil sample not contaminated by heavy metals, then add 200 mg of cadmium, 200 mg of mercury, 500 mg of arsenic, and 500 mg of lead into the soil sample, add water to the soil at a liquid-to-solid ratio of 1:1 ml / mg, stir evenly, and age for 24 hours before naturally air-drying to obtain the heavy metal contaminated soil sample for test.

[0023] Stabilization treatment of heavy metal contaminated soil: Weigh 50g of the heavy metal contaminated soil sample and 5g of high-efficiency heavy metal stabilizer and place them in a 250mL beaker. Add 55mL of water to the beaker at a liquid-solid ratio of 1:1ml / mg, stir evenly, seal the beaker with a perforated plastic wrap, and semi-seal for 28 days. After the curing is completed, the nine groups of samples are dried at a constant temperature, sieved through a 200-mesh sieve, and set aside.

[0024] Leaching test, heavy metal ion concentration detection and calculation of heavy metal stabilization rate: Toxicity leaching test was carried out on heavy metal contaminated soil and stabilized soil samples in accordance with the "Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007). The concentrations of lead and cadmium pollutants in the leachate were determined in accordance with the "Determination of 32 Elements in Water Quality by Inductively Coupled Plasma Emission Spectrometry" (HJ 776-2015); the concentrations of arsenic and mercury pollutants in the leachate were determined in accordance with the "Determination of Mercury, Arsenic, Selenium, Bismuth and Antimony in Water Quality by Atomic Fluorescence Spectrometry" (HJ 694-2014). The stabilization efficiency of heavy metal pollutants M (M: arsenic, cadmium, lead, mercury) was calculated according to the following formula, where For the stabilization efficiency of heavy metal pollutants, is the concentration of heavy metal M in the leachate of heavy metal contaminated soil (mg / L), The concentration of heavy metal M in the leaching solution after stabilization treatment (mg / L). The test results are shown in Table 1.

[0025]

[0026] Table 1 Effect of the mass ratio of ammonium chloride, municipal sludge and electrolytic manganese slag on the performance of the prepared heavy metal contaminated soil stabilizer

[0027] It can be seen from Table 1 that when the mass ratio of ammonium chloride, municipal sludge and electrolytic manganese slag is less than 0.5:10:100 (such as in Table 1, 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 amount of ammonium chloride and municipal sludge used is small, and the reaction of ammonium chloride, municipal sludge and electrolytic manganese slag is insufficient in the subsequent roasting process, resulting in the stabilization rates of cadmium, mercury, arsenic and lead all decreasing significantly with the decrease of the mass ratio of ammonium chloride, municipal sludge and electrolytic manganese slag. 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, the mass ratio of ammonium chloride, municipal sludge and electrolytic manganese slag is 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), ammonium chloride, municipal sludge and electrolytic manganese slag are mixed, and 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. The manganese slag sludge is roasted, and during the roasting process, ammonium chloride reacts with the iron, manganese, aluminum and calcium minerals in the electrolytic manganese slag to generate chloride gas, which enters the flue gas to form dust that can be recovered. The water vapor and small molecular organic matter released by the pyrolysis of organic matter in the sludge and the carbon-based substances formed can strengthen the combination of iron, manganese, aluminum, calcium and chloride ions, and strengthen the release and volatilization of iron, manganese, aluminum and calcium by increasing the saturated vapor pressure of chloride and reducing the binding energy. The ammonium ions can react with the nitrates in the electrolytic manganese slag and sludge and the nitrogen oxides formed by the oxidation of nitrogen during the roasting process to form nitrogen, and make the roasting material more fluffy. Finally, the heavy metal cadmium, mercury, arsenic and lead achieved by the soil stabilizer were greater than 87%, 89%, 92% and 90% respectively. When the mass ratio of ammonium chloride, municipal sludge, and electrolytic manganese slag is greater than 2.5:50:100 (such as in Table 1, 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), excessive addition of ammonium chloride and municipal sludge will cause an imbalance in the material reaction during the roasting process, resulting in a decrease in the stabilization rate of heavy metals such as cadmium, mercury, arsenic, and lead as the mass ratio of ammonium chloride, municipal sludge, and electrolytic manganese slag further increases. Therefore, in general, combining 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 conducive to improving the heavy metal stabilization performance of the prepared stabilizer.

[0028] Example 2 Effect of the mass ratio of recycled dust and straw powder on the performance of the prepared heavy metal contaminated soil stabilizer Ammonium chloride, municipal sludge and electrolytic manganese slag are mixed in a mass ratio of 2.5:50:100, stirred evenly, and ammonium-loaded manganese slag sludge is obtained. The ammonium manganese sludge is roasted to obtain roasted slag, and the flue gas dust recovered in the roasting process is the recovered dust, wherein the roasting time is 2.5 hours, and the roasting temperature is 1000°C. The recovered dust and straw powder are mixed in a mass ratio of 1:100, 1.5:100, 2:100, 2.5:100, 7.5:100, 12.5:100, 15:100, 17.5:100, and 20:100, stirred evenly, and mixed powder is obtained. The landfill leachate and the mixed powder are mixed in a liquid-solid ratio of 15:1 mL / g, stirred evenly, and then introduced into a hydrothermal kettle for hydrothermal reaction to obtain a hydrothermal activated slurry, wherein the temperature of the hydrothermal reaction is 240°C and the hydrothermal time is 3 hours. The calcined slag is ground into powder to obtain calcined powder, fly ash, hydrothermal activated slurry and calcined powder are mixed in a mass ratio of 10:45:100, the mixture is stirred evenly and aged for 7 days to obtain a heavy metal contaminated soil stabilizer.

[0029] The preparation of heavy metal contaminated soil, stabilization treatment of heavy metal contaminated soil, leaching test, heavy metal ion concentration detection and calculation of heavy metal stabilization rate are all the same as in Example 1.

[0030] Table 2 Effect of the mass ratio of recycled dust and straw powder on the performance of the prepared heavy metal contaminated soil stabilizer

[0031] It can be seen from Table 2 that when the mass ratio of recycled dust to straw powder is less than 2.5:100 (such 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), the amount of recycled dust added is small, and the reaction of recycled dust and straw powder during the hydrothermal process is insufficient, resulting in the stabilization rates of cadmium, mercury, arsenic and lead all significantly decreasing 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 (such 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, the straw powder will undergo hydrolysis, decarboxylation, dehydration and condensation reactions and produce a variety of products. High molecular polymers such as cellulose, hemicellulose and lignin in straw will be hydrolyzed under hydrothermal conditions to produce oligosaccharides, monosaccharides (such as glucose, xylose, etc.), organic acids and phenolic compounds. Some organic matter in straw may undergo decarboxylation reaction to produce carbon dioxide and corresponding hydrocarbon compounds. Some unstable intermediates or initial reactants may undergo dehydration reaction to produce more stable compounds. Monosaccharides and other small molecular compounds produced by hydrolysis may further undergo condensation reaction to produce high molecular compounds such as polysaccharides, lignin derivatives or melanoidins. During the hydrothermal reaction, the products such as sugars, organic acids, phenolic compounds generated by the straw powder reaction undergo oxidation, reduction and complexation reactions with chlorides in the recovered dust to produce a multi-organic inorganic precipitation mixture. The multivalent iron and manganese in the mixture form a co-precipitation with aluminum and calcium, and the organic matter is loaded on the co-precipitation surface or combined with iron, manganese, aluminum and calcium, and doped in the co-precipitation mixture. Finally, the heavy metal cadmium, mercury, arsenic and lead achieved by the soil stabilizer are greater than 93%, 94%, 95% and 95% respectively. When the mass ratio of recycled dust to straw powder is greater than 12.5:100 (such 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 addition of recycled dust will cause imbalance of material reaction during the hydrothermal reaction, resulting in a decrease in the stabilization rate of heavy metals cadmium, mercury, arsenic and lead as the mass ratio of recycled dust to straw powder further increases. Therefore, in general, combining benefits and costs, when the mass ratio of recycled dust to straw powder is equal to 2.5~12.5:100, it is most conducive to improving the heavy metal stabilization performance of the prepared stabilizer.

[0032] Example 3 Effect of the mass ratio of fly ash, hydrothermal activated slurry and calcined powder on the performance of the prepared heavy metal contaminated soil stabilizer Ammonium chloride, municipal sludge, and electrolytic manganese slag are mixed in a mass ratio of 2.5:50:100, stirred evenly, and ammonium-loaded manganese slag sludge is obtained. The ammonium manganese sludge is roasted to obtain roasted slag, and the flue gas dust recovered during the roasting process is the recovered dust, wherein the roasting time is 4.5 hours, and the roasting temperature is 1250°C. The recovered dust and straw powder are mixed in a mass ratio of 12.5:100, stirred evenly, and a mixed powder is obtained. The landfill leachate and the mixed powder are mixed in a liquid-solid ratio of 25:1mL / g, stirred evenly, and then introduced into a hydrothermal kettle for hydrothermal reaction to obtain a hydrothermal activated slurry, wherein the temperature of the hydrothermal reaction is 360°C, and the hydrothermal time is 5.5 hours. The calcined slag was ground into powder to obtain calcined powder, and the calcined powder was prepared according to the mass ratio 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. 0, 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 were mixed with fly ash, hydrothermal activated slurry and roasting powder, stirred evenly and aged for 12 days to obtain a heavy metal contaminated soil stabilizer.

[0033] The preparation of heavy metal contaminated soil, stabilization treatment of heavy metal contaminated soil, leaching test, heavy metal ion concentration detection and calculation of heavy metal stabilization rate are all the same as in Example 1.

[0034] Table 3 Effect of fly ash, hydrothermal activated slurry and roasted powder mass ratio on the performance of the prepared heavy metal contaminated soil stabilizer

[0035] It can be seen from Table 3 that when the mass ratio of fly ash, hydrothermal activated slurry and roasted powder is less than 5:30:100 (such as in Table 3, the mass ratio of fly ash, hydrothermal activated slurry and roasted 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), less fly ash and hydrothermal activated slurry are added, and the fly ash, hydrothermal activated slurry and roasted powder do not react fully during the aging process, 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, hydrothermal activated slurry and roasted powder is equal to 5~ 15:30~60:100 (as shown in Table 3, the mass ratio of fly ash, hydrothermal activated slurry, and roasted 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), fly ash, hydrothermal activated slurry, and roasted powder are mixed. During the stirring and aging process, the active silicates and cations in the fly ash fully react with the multi-organic inorganic precipitation mixture mixed with multi-organic matter in the hydrothermal activated slurry and the active silicates and aluminum ferrites in the roasted powder to form a highly active heavy metal contaminated soil stabilizer. Finally, the heavy metal cadmium, mercury, arsenic, and lead achieved by the soil stabilizer are greater than 96%, 98%, 98%, and 97%, respectively. When the mass ratio of fly ash, hydrothermal activated slurry, and calcined powder is greater than 15:60:100 (such as in Table 3, the mass ratio of fly ash, hydrothermal 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), fly ash and hydrothermal activated slurry are added excessively, and the material reaction is unbalanced during the aging process, resulting in the stabilization rate of heavy metals cadmium, mercury, arsenic, and lead decreasing as the mass ratio of fly ash, hydrothermal activated slurry, and calcined powder further increases. Therefore, in general, combined with benefits and costs, when the mass ratio of fly ash, hydrothermal activated slurry, and calcined powder is equal to 5~15:30~60:100, it is most conducive to improving the heavy metal stabilization performance of the prepared stabilizer.

[0036] Comparative Example 1 Effects of different processes on the performance of heavy metal contaminated soil stabilizers The process of the present invention is as follows: ammonium chloride, municipal sludge and electrolytic manganese slag are mixed in a mass ratio of 2.5:50:100, stirred evenly, and ammonium-loaded manganese slag sludge is obtained. The ammonium manganese sludge is roasted to obtain roasted slag, and the flue gas dust recovered in the roasting process is the recovered dust, wherein the roasting time is 4.5 hours and the roasting temperature is 1250°C. The recovered dust and straw powder are mixed in a mass ratio of 12.5:100, stirred evenly, and mixed powder is obtained. The landfill leachate and the mixed powder are mixed in a liquid-solid ratio of 25:1mL / g, stirred evenly, and then introduced into a hydrothermal kettle for hydrothermal reaction to obtain a hydrothermal activated slurry, wherein the temperature of the hydrothermal reaction is 360°C and the hydrothermal time is 5.5 hours. The roasted slag is ground into powder to obtain roasted powder, and fly ash, hydrothermal activated slurry and roasted powder are mixed in a mass ratio of 15:60:100, stirred evenly, and aged for 12 days to obtain a heavy metal contaminated soil stabilizer.

[0037] Comparative process 1: Ammonium chloride, municipal sludge, and electrolytic manganese slag are mixed in a mass ratio of 2.5:50:100, stirred evenly, and ammonium-loaded manganese slag sludge is obtained. The ammonium manganese sludge is roasted to obtain roasted slag, and the flue gas dust recovered during the roasting process is the recovered dust, wherein the roasting time is 4.5 hours and the roasting temperature is 1250°C. Recovered dust and straw powder are mixed in a mass ratio of 12.5:100, stirred evenly, and mixed powder is obtained. Water and mixed powder are mixed in a liquid-solid ratio of 25:1mL / g, stirred evenly, and then introduced into a hydrothermal kettle for hydrothermal reaction to obtain a hydrothermal activated slurry, wherein the temperature of the hydrothermal reaction is 360°C and the hydrothermal time is 5.5 hours. The roasted slag is ground into powder to obtain roasted powder, and fly ash, hydrothermal activated slurry, and roasted powder are mixed in a mass ratio of 15:60:100, stirred evenly, and aged for 12 days to obtain a heavy metal contaminated soil stabilizer.

[0038] Comparative process 2: ammonium chloride, municipal sludge, and electrolytic manganese slag are mixed in a mass ratio of 2.5:50:100, stirred evenly, and ammonium-loaded manganese slag sludge is obtained. The ammonium manganese sludge is roasted to obtain roasted slag, and the flue gas dust recovered during the roasting process is the recovered dust, wherein the roasting time is 4.5 hours, and the roasting temperature is 1250°C. The landfill leachate and the recovered dust are mixed in a liquid-solid ratio of 25:1mL / g, stirred evenly, and then introduced into a hydrothermal kettle for hydrothermal reaction to obtain a hydrothermal activated slurry, wherein the temperature of the hydrothermal reaction is 360°C, and the hydrothermal time is 5.5 hours. The roasted slag is ground into powder to obtain roasted powder, and fly ash, hydrothermal activated slurry, and roasted powder are mixed in a mass ratio of 15:60:100, stirred evenly, and aged for 12 days to obtain a heavy metal contaminated soil stabilizer.

[0039] Comparative process 3: ammonium chloride, municipal sludge, and electrolytic manganese slag are mixed in a mass ratio of 2.5:50:100, stirred evenly, and ammonium-loaded manganese slag sludge is obtained. The ammonium manganese sludge is roasted to obtain roasted slag, and the flue gas dust recovered during the roasting process is the recovered dust, wherein the roasting time is 4.5 hours and the roasting temperature is 1250°C. The recovered dust and straw powder are mixed in a mass ratio of 12.5:100, stirred evenly, and mixed powder is obtained. The landfill leachate and the mixed powder are mixed in a liquid-solid ratio of 25:1mL / g, stirred evenly, and then introduced into a hydrothermal kettle for hydrothermal reaction to obtain a hydrothermal activated slurry, wherein the temperature of the hydrothermal reaction is 360°C and the hydrothermal time is 5.5 hours. The roasted slag is ground into powder to obtain roasted powder, and the hydrothermal activated slurry and roasted powder are mixed in a mass ratio of 60:100, stirred evenly, and aged for 12 days to obtain a heavy metal contaminated soil stabilizer.

[0040] The preparation of heavy metal contaminated soil, stabilization treatment of heavy metal contaminated soil, leaching test, heavy metal ion concentration detection and calculation of heavy metal stabilization rate are all the same as in Example 1.

[0041] Table 4 Effects of different processes on the performance of heavy metal contaminated soil stabilizers

[0042] It can be seen from Table 4 that the heavy metal stabilization rate achieved by the heavy metal contaminated soil stabilizer prepared by the process of the present invention is significantly higher than that of the heavy metal contaminated soil stabilizer prepared by comparison process 1, comparison process 2, and comparison 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; (2) roasting the ammonium manganese sludge to obtain roasting slag and grinding it into roasting powder, and the flue gas dust recovered in the roasting process is the recovered dust; (3) Mixing the recycled dust and straw powder and stirring them evenly to obtain mixed powder; (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) The fly ash, hydrothermal activated slurry and roasted powder are mixed, stirred evenly, and aged to obtain a heavy metal contaminated soil stabilizer.

2. The method according to claim 1, characterized in that: The mass ratio of ammonium chloride, municipal sludge and electrolytic manganese slag described in step (1) is 0.5~2.5:10~50:

100.

3. 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.

4. The method according to claim 1, characterized in that: The mass ratio of the recovered dust to the straw powder in step (3) is 2.5-12.5:

100.

5. 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.

6. 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.

7. The method according to claim 1, characterized in that The mass ratio of fly ash, hydrothermal activated slurry and roasted powder in step (5) is 5-15:30-60:

100.

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

9. Use of the soil stabilizer prepared by the method according to any one of claims 1 to 8 in treating heavy metal pollution.

10. The use according to claim 9, characterized in that: The heavy metals include cadmium, mercury, arsenic and / or lead.

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