Treatment method and application of heavy metal stabilized red mud based on multielement solid waste synergy

Abstract

The invention discloses a treatment method of heavy metal stabilized red mud based on multielement solid waste synergy and application of the treatment method. According to the method, four solid wastes including coal mine area soil, vinasse, acidic biochar and garden soil are adopted as stabilizers, the water extraction state content of the heavy metals in the red mud is reduced in a multi-element combined adding mode, simultaneous stabilization of multiple heavy metals in the red mud is achieved, and the highest reduction rate reaches 99.0%. Harmless treatment of the red mud and resource utilization of solid waste such as coal mine area soil, vinasse, acidic charcoal and garden soil are achieved, and the method has the advantage of treating waste with waste. The method is easy to operate, low in cost, free of complex equipment and easy to industrially popularize and apply. The treated red mud can be used in the fields of building materials, roadbed materials or soil amendments and the like, and cyclic utilization of resources is realized.

Description

Technical Field

[0001] This invention belongs to the field of industrial solid waste co-treatment and resource utilization technology, specifically relating to a treatment method and application of heavy metal stabilization red mud based on multi-component solid waste synergy. Background Technology

[0002] Red mud is a highly alkaline solid waste generated during the production of alumina from bauxite. According to statistics from the International Aluminium Institute, approximately 1-2 tons of red mud are generated for every ton of alumina produced, with global annual emissions exceeding 150 million tons and cumulative stockpiles exceeding 4 billion tons. Red mud contains heavy metals such as Al, As, Cd, Cr, Li, Ni, Pb, Sb, Sn, and V, which can easily migrate and spread through infiltration and dust during long-term storage, posing a serious threat to the surrounding soil-groundwater ecosystem.

[0003] The current red mud heavy metal treatment technology mainly faces the following technical bottlenecks: (1) Chemical stabilization method: It requires the addition of chemical agents such as phosphates and silicates. Although it is effective in the short term, it has problems such as high treatment cost and the possibility of secondary pollution caused by agent residue; (2) Solidification / stabilization technology: It uses cement and other cementitious materials for solidification, which leads to an increase in treatment volume of 30%-50%, and there is a risk of cracking of solidified body and re-dissolution of heavy metals under long-term exposure; (3) Heat treatment method: It requires maintaining a high temperature of above 800℃, with energy consumption as high as 150-200kWh / ton, and some heavy metals (such as As and Pb) are easy to volatilize at high temperatures; (4) Single stabilizer method: It has poor adaptability to multi-metal complex pollution systems. For example, common passivating agents are effective for Cd but not for Cr.

[0004] On the other hand, the treatment of solid wastes such as contaminated soil (AS) from coal mines, distiller's grains (DG), and acidic biochar (AB) made from rice husk waste also faces technical and economic challenges. These wastes have unique physicochemical properties: AS is rich in iron and manganese oxides, DG contains a large number of organic functional groups, and AB has a well-developed porous structure and surface acidic sites. How to construct a synergistic treatment system of "waste-to-waste" through the principles of materials science and interface chemistry to achieve the dual goals of harmless treatment of red mud and resource utilization of other solid wastes has become a key scientific problem that urgently needs to be solved in the fields of environmental engineering and circular economy.

[0005] To address the aforementioned issues, this invention constructs a three-in-one technical system integrating "materials-proportioning-process" to achieve efficient stabilization of multi-metal composite pollution in red mud, while simultaneously enabling the synergistic resource utilization of various solid wastes. Summary of the Invention

[0006] The purpose of this invention is to address the technical bottlenecks of existing red mud treatment technologies, such as low treatment efficiency, high cost, and significant risk of secondary pollution, by innovatively proposing a method for stabilizing red mud with heavy metals based on the synergistic effect of multiple solid wastes, and its application. This method achieves efficient stabilization of multi-metal complex pollution in red mud by constructing a three-in-one technical system of "materials-proportioning-process," while simultaneously realizing the synergistic resource utilization of various solid wastes.

[0007] To achieve the above objectives, the technical solution of the present invention is: a method for treating red mud with heavy metal stabilization based on the synergistic effect of multiple solid wastes, which uses four types of solid wastes—coal mine soil, distiller's grains, acidic biochar, and garden soil—as stabilizers, and reduces the water-extractable content of heavy metals in red mud through the combined addition of multiple materials.

[0008] The processing method is specifically carried out according to the following steps:

[0009] (1) Soil pretreatment in coal mining areas: Soil from coal mining areas is dried at 55-65℃ until the moisture content is <5%, and then passed through a 1.5-2.5mm sieve to obtain pretreated soil from coal mining areas;

[0010] (2) Garden soil pretreatment: Take garden soil and dry it at 55-65℃ until the moisture content is <5%, and pass it through a 1.5-2.5mm sieve to obtain pretreated garden soil;

[0011] (3) Pretreatment of distiller's grains: Dry the distiller's grains at 55-65℃ until the moisture content is <5%, crush them and pass them through a 1.5-2.5mm sieve to obtain pretreated distiller's grains;

[0012] (4) Preparation of acidic biochar: Rice husks are passed through a 1.5-2.5 mm sieve and then immersed in a 0.1 mol / L ferrous sulfate solution and left to stand for 7-9 h. The ratio of rice husks to 0.1 mol / L ferrous sulfate solution is 0.8-1.2 g: 8-12 mL to obtain pretreated rice husks. The pretreated rice husks are dried at 55-65℃ until the moisture content is <5%. Then, they are placed in a carbonization furnace and heated to 450-550℃ at a heating rate of 9-11℃ / min under nitrogen protection. The temperature is maintained at 450-550℃ for stable carbonization for 1.5-2.5 h. After heating is stopped, the experimental furnace is cooled to room temperature, and the furnace is opened to discharge the material to obtain acidic biochar.

[0013] (5) Mixed curing and maturation: Take red mud and add 0.8-1.2wt% of pretreated coal mining soil, 0.8-1.2wt% of pretreated garden soil, 0.8-1.2wt% of pretreated distiller's grains and 0.8-1.2wt% of acidic biochar. Add deionized water and adjust the moisture content to 55-65%. Cure at 20-30℃ for 28-32 days to obtain heavy metal stabilized red mud.

[0014] In step (1) above, the soil from the coal mining area is dried at 60°C until the moisture content is <5%, and then passed through a 2mm sieve to obtain pretreated coal mining area soil; the total amount of iron and manganese oxides in the coal mining area soil is ≥7wt%, of which Fe2O3 is ≥5wt% and MnO2 is ≥2wt%.

[0015] In step (2) above, garden soil is dried at 60°C until the moisture content is <5%, and then passed through a 2mm sieve to obtain pretreated garden soil; the garden soil is topsoil with a plant growth history and contains organic matter ≥2wt%.

[0016] Specifically, in step (2) above, the topsoil is taken from a location no less than 20cm below the ground surface.

[0017] In step (3) above, the lees are pretreated by drying the lees at 60°C until the moisture content is less than 5%, crushing them and passing them through a 2mm sieve to obtain pretreated lees.

[0018] In step (4) above, the preparation of acidic biochar is as follows: rice husks are passed through a 2mm sieve and then immersed in a 0.1mol / L ferrous sulfate solution and left to stand for 8 hours. The ratio of rice husks to 0.1mol / L ferrous sulfate solution is 1g:10mL to obtain pretreated rice husks. The pretreated rice husks are dried at 60℃ until the moisture content is <5%, and then placed in a carbonization furnace and heated to 500℃ at a heating rate of 10℃ / min under nitrogen protection. The temperature is maintained at 500℃ for stable carbonization for 2 hours. After heating is stopped, the experimental furnace is cooled to room temperature, and the furnace is opened to discharge the material, thus obtaining acidic biochar.

[0019] In the aforementioned step (5), the mixture is cured and matured: take red mud and add 1 wt% of pretreated coal mine soil, 1 wt% of pretreated garden soil, 1 wt% of pretreated distiller's grains and 1 wt% of acidic biochar to mix, add deionized water, adjust the moisture content to 60%, and cure at 25℃ for 30 days to obtain heavy metal stabilized red mud.

[0020] The aforementioned heavy metals include one or more of Al, As, Cd, Cr, Li, Ni, Pb, Sb, Sn, and V.

[0021] An application of the aforementioned heavy metal stabilized red mud in building materials, roadbed materials, or soil conditioners.

[0022] The technical solution of the present invention has the following beneficial effects:

[0023] 1. This invention pioneers a quaternary combined stabilization process, "AS-DG-AB-GS," which constructs a multi-level stabilization system through the synergistic effect of various solid wastes. It develops a multi-element ratio optimization technology to ensure the synergistic stabilization effect of different heavy metals. This method is applicable to the comprehensive treatment of red mud contaminated with complex heavy metals, achieving the synergistic resource utilization of industrial solid waste and agricultural waste. It provides a highly efficient and reliable new stabilization method for the harmless treatment of red mud, and has broad application prospects in the fields of industrial solid waste treatment and soil remediation.

[0024] 2. This invention uses a combination of multiple solid waste additives to simultaneously stabilize multiple heavy metals in red mud, with a maximum reduction rate of 99.0%.

[0025] 3. This invention realizes the harmless treatment of red mud and the resource utilization of solid wastes such as coal mining soil, distiller's grains, acidic biochar, and garden soil, and has the characteristics of "treating waste with waste".

[0026] 4. The method of the present invention is simple to operate, low in cost, requires no complex equipment, and is easy to promote and apply in industrial applications.

[0027] 5. The treated red mud can be used in building materials, roadbed materials, or soil conditioners, realizing the recycling of resources. Attached Figure Description

[0028] Figure 1 The images show the physical samples of fourth-order stabilizers AS, DG, AB, GS, and a mixture of fourth-order stabilizers AS+DG+AB+GS. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The present invention will be further described below with reference to the embodiments. These embodiments are merely further supplements and explanations of the present invention, and are not intended to limit the invention.

[0030] Example 1: Material Pretreatment and Preparation

[0031] (1) Soil pretreatment in coal mining area: Soil from coal mining area is dried at 60℃ to a moisture content of <5%, and then passed through a 2mm sieve to obtain pretreated coal mining area soil, abbreviated as AS.

[0032] The total amount of iron and manganese oxides in the soil of coal mining areas is ≥7wt% (of which Fe2O3 ≥5wt% and MnO2 ≥2wt%).

[0033] (2) Garden soil pretreatment: Garden soil is dried at 60℃ until the moisture content is <5%, and then passed through a 2mm sieve to obtain pretreated garden soil, abbreviated as GS;

[0034] Garden soil is the topsoil (0-20cm) with a history of plant growth, containing ≥2wt% organic matter.

[0035] (3) Pretreatment of distiller's grains: The distiller's grains are dried at 60°C until the moisture content is <5%, crushed and passed through a 2mm sieve to obtain pretreated distiller's grains, abbreviated as DG.

[0036] (4) Preparation of acidic biochar: Rice husks were passed through a 2 mm sieve and then immersed in a 0.1 mol / L ferrous sulfate solution and left to stand for 8 h. The ratio of rice husks to 0.1 mol / L ferrous sulfate solution was 1 g: 10 mL to obtain pretreated rice husks. The pretreated rice husks were dried at 60 °C until the moisture content was <5%. Then, they were placed in a carbonization furnace and heated to 500 °C at a heating rate of 10 °C / min under nitrogen protection. The temperature was maintained at 500 °C for stable carbonization for 2 h. After heating was stopped, the experimental furnace was cooled to room temperature and the material was discharged to obtain acidic biochar, abbreviated as AB.

[0037] The materials used in Examples 2-5 below are all materials obtained by pretreatment and preparation in Example 1.

[0038] Example 2: One-element addition processing

[0039] Take red mud samples (RM) and add AS, DG, AB or GS as described in Example 1. The amount of AS, DG, AB or GS added is 4 wt% of the total amount of red mud sample. Mix thoroughly and then add 60% deionized water to maintain a moisture content of 60%. After curing for 30 days, four groups of heavy metal stabilized red mud were obtained, namely RM+AS group, RM+DG group, RM+AB group and RM+GS group. The content of heavy metals in water-extracted form was determined.

[0040] The results showed that AS had the best stabilizing effect on As, with a reduction rate of 74.8%; DG had the best stabilizing effect on Al, with a reduction rate of 55.8%; AB had the best stabilizing effect on Cd, with a reduction rate of 79.7%; and GS had the best stabilizing effect on Sn, with a reduction rate of 81.4%.

[0041] Example 3: Binary Additive Treatment

[0042] (1) Take a red mud sample (RM), add AS and DG from Example 1. The amount of AS and DG added is 2wt% of the total amount of red mud sample. Mix thoroughly and evenly, then add 60% deionized water to maintain a moisture content of 60%. After curing for 30 days, heavy metal stabilized red mud of RM+AS+DG group is obtained, and the water-extracted heavy metal content is determined.

[0043] (2) Take a red mud sample (RM), add AS and AB from Example 1. The amount of AS and AB added is 2wt% of the total amount of red mud sample. Mix thoroughly and evenly, then add 60% deionized water to maintain a moisture content of 60%. After curing for 30 days, the heavy metal stabilized red mud of RM+AS+AB group is obtained, and the water-extracted heavy metal content is determined.

[0044] (3) Take a red mud sample (RM), add AS and GS from Example 1. The amount of AS and GS added is 2wt% of the total amount of red mud sample. Mix thoroughly and evenly, then add 60% deionized water to maintain a moisture content of 60%. After curing for 30 days, the heavy metal stabilized red mud of RM+AS+GS group is obtained, and the water-extracted heavy metal content is determined.

[0045] (4) Take a red mud sample (RM), add DG and AB from Example 1. The amount of DG and AB added is 2wt% of the total amount of red mud sample. Mix thoroughly and evenly, then add 60% deionized water to maintain a moisture content of 60%. After curing for 30 days, heavy metal stabilized red mud of DG+AB group is obtained, and the water-extracted heavy metal content is determined.

[0046] (5) Take a red mud sample (RM), add DG and GS from Example 1. The amount of DG and GS added is 2wt% of the total amount of red mud sample. Mix thoroughly and evenly, then add 60% deionized water to maintain a moisture content of 60%. After curing for 30 days, the heavy metal stabilized red mud of RM+DG+GS group is obtained, and the water-extracted heavy metal content is determined.

[0047] (6) Take a red mud sample (RM), add AB and GS from Example 1. The amount of AB and GS added is 2wt% of the total amount of red mud sample. Mix thoroughly and evenly, then add 60% deionized water to maintain a moisture content of 60%. After curing for 30 days, the heavy metal stabilized red mud of RM+AB+GS group is obtained, and the water-extracted heavy metal content is determined.

[0048] The results showed that the RM+AS+DG combination had the best stabilization effect on Pb, with a reduction rate of 86.4%; the RM+DG+AB combination had the best stabilization effect on Cr, with a reduction rate of 84.3%; and the RM+DG+GS combination had the best stabilization effect on Cd, with a reduction rate of 87.7%.

[0049] Example 4: Ternary Additive Treatment

[0050] (1) Take a red mud sample (RM), add AS, DG and AB from Example 1. The amount of AB, DG and AB added is 1.33 wt% of the total amount of red mud sample. Mix thoroughly and evenly, then add 60% deionized water to maintain a moisture content of 60%. After curing for 30 days, heavy metal stabilized red mud of group RM+AS+DG+AB is obtained, and the water-extracted heavy metal content is determined.

[0051] (2) Take a red mud sample (RM), add AS, DG and GS from Example 1. The amount of AS, DG and GS added is 1.33 wt% of the total amount of red mud sample. Mix thoroughly and evenly, then add 60% deionized water to maintain a moisture content of 60%. After curing for 30 days, heavy metal stabilized red mud of RM+AS+DG+GS group is obtained, and the water-extracted heavy metal content is determined.

[0052] (3) Take a red mud sample (RM), add AS, AB and GS from Example 1. The amount of AS, AB and GS added is 1.33 wt% of the total amount of red mud sample. Mix thoroughly and evenly, then add 60% deionized water to maintain a moisture content of 60%. After curing for 30 days, the heavy metal stabilized red mud of RM+AS+AB+GS group is obtained, and the water-extracted heavy metal content is determined.

[0053] (4) Take a red mud sample (RM), add DG, AB and GS from Example 1. The amount of DG, AB and GS added is 1.33 wt% of the total amount of red mud sample. Mix thoroughly and evenly, then add 60% deionized water to maintain a moisture content of 60%. After curing for 30 days, the heavy metal stabilized red mud of RM+DG+AB+GS group is obtained, and the water-extracted heavy metal content is determined.

[0054] The results showed that the RM+DG+AB+GS combination had the best stabilization effect on Pb, with a reduction rate of 96.6%; the RM+AS+DG+AB combination had the best stabilization effect on Cd, with a reduction rate of 88.4%.

[0055] Example 5: Quaternary Addition Process

[0056] Take a red mud sample (RM), add AS, DG, AB and GS from Example 1. The amount of AS, DG, AB and GS added is 1 wt% of the total amount of red mud sample. Mix thoroughly and evenly, then add 60% deionized water to maintain a moisture content of 60%. After curing for 30 days, heavy metal stabilized red mud of group RM+AS+DG+AB+GS is obtained, and the content of water-extracted heavy metals is determined.

[0057] The results showed that this combination had the best stabilizing effect on Pb, with a reduction rate of 99.0%, followed by Cr, with a reduction rate of 86.2%. It also achieved a reduction rate of 85.2% for Cd and 85.7% for Sn, both of which were removed simultaneously and efficiently. It also showed some effect on As (reduction rate of 61.1%), V (reduction rate of 45.0%), and Al (reduction rate of 21.6%).

[0058] Table 1 (Effect of Reduction of Water-Extracted Content in Red Mud (%)) and the corresponding Table 2 (Concentration of Water-Extracted Content in Red Mud) show the effects of the mono-component (Example 2), binary (Example 3), ternary (Example 4), and quaternary treatment groups (Example 5) of the present invention on the reduction of water-extracted content of various heavy metals in red mud.

[0059] Table 1. Reduction effect of water-extractable content of red mud in different treatment groups (%)

[0060]

[0061] Note: The data in the table represent the percentage decrease in water-extractable content; negative values ​​indicate an increase.

[0062] Table 2. Changes in the water-extractable content of red mud in different treatment groups.

[0063]

[0064] Example 6: Quaternary Addition Process

[0065] 1. Material pretreatment and preparation

[0066] (3) Soil pretreatment in coal mining areas: Soil from coal mining areas is dried at 65℃ until the moisture content is <5%, and then passed through a 1.5mm sieve to obtain pretreated coal mining area soil, abbreviated as AS;

[0067] The total amount of iron and manganese oxides in the soil of coal mining areas is ≥7wt% (of which Fe2O3 ≥5wt% and MnO2 ≥2wt%).

[0068] (4) Garden soil pretreatment: Garden soil is dried at 65℃ until the moisture content is <5%, and then passed through a 1.5mm sieve to obtain pretreated garden soil, abbreviated as GS;

[0069] Garden soil is the topsoil (0-20cm) with a history of plant growth, containing ≥2wt% organic matter.

[0070] (3) Pretreatment of distiller's grains: The distiller's grains are dried at 65°C until the moisture content is <5%, crushed and passed through a 1.5mm sieve to obtain pretreated distiller's grains, abbreviated as DG.

[0071] (4) Preparation of acidic biochar: Rice husks were passed through a 1.5 mm sieve and then immersed in a 0.1 mol / L ferrous sulfate solution and left to stand for 7 h. The ratio of rice husks to 0.1 mol / L ferrous sulfate solution was 0.8 g: 12 mL to obtain pretreated rice husks. The pretreated rice husks were dried at 65 °C until the moisture content was <5%. Then, they were placed in a carbonization furnace and heated to 450 °C at a heating rate of 9 °C / min under nitrogen protection. The temperature was maintained at 450 °C for stable carbonization for 2.5 h. After heating was stopped, the experimental furnace was cooled to room temperature and the material was discharged to obtain acidic biochar, abbreviated as AB.

[0072] 2. Take a red mud sample (RM) and add AS, DG, AB and GS. The amount of AS, DG, AB and GS added is 1.2wt% of the total amount of red mud sample. Mix thoroughly and evenly, then add 55% deionized water to maintain a moisture content of 55%. After curing for 32 days, heavy metal stabilized red mud of group RM+AS+DG+AB+GS is obtained, and the content of water-extracted heavy metals is determined.

[0073] Example 7: Quaternary Addition Process

[0074] 1. Material pretreatment and preparation

[0075] (5) Soil pretreatment in coal mining areas: Soil from coal mining areas is dried at 55°C until the moisture content is <5%, and then passed through a 2.5mm sieve to obtain pretreated coal mining area soil, abbreviated as AS;

[0076] The total amount of iron and manganese oxides in the soil of coal mining areas is ≥7wt% (of which Fe2O3 ≥5wt% and MnO2 ≥2wt%).

[0077] (6) Garden soil pretreatment: Garden soil is dried at 55℃ until the moisture content is <5%, and then passed through a 2.5mm sieve to obtain pretreated garden soil, abbreviated as GS;

[0078] Garden soil is the topsoil (0-20cm) with a history of plant growth, containing ≥2wt% organic matter.

[0079] (3) Pretreatment of distiller's grains: The distiller's grains are dried at 55°C until the moisture content is <5%, crushed and passed through a 2.5mm sieve to obtain pretreated distiller's grains, abbreviated as DG.

[0080] (4) Preparation of acidic biochar: Rice husks were passed through a 2.5 mm sieve and then immersed in a 0.1 mol / L ferrous sulfate solution and left to stand for 9 h. The ratio of rice husks to 0.1 mol / L ferrous sulfate solution was 1.2 g: 8 mL to obtain pretreated rice husks. The pretreated rice husks were dried at 55 °C until the moisture content was <5%. Then, they were placed in a carbonization furnace and heated to 550 °C at a heating rate of 11 °C / min under nitrogen protection. The temperature was maintained at 550 °C for stable carbonization for 1.5 h. After heating was stopped, the experimental furnace was cooled to room temperature and the material was discharged to obtain acidic biochar, abbreviated as AB.

[0081] 2. Mixed curing and maturation:

[0082] Red mud sample (RM) was mixed with AS, DG, AB and GS. The amount of each of AS, DG, AB and GS added was 0.8 wt% of the total amount of red mud sample. The mixture was thoroughly mixed and then 65% deionized water was added to maintain a moisture content of 65%. After curing for 28 days, heavy metal stabilized red mud of group RM+AS+DG+AB+GS was obtained, and the content of heavy metals in water was determined.

[0083] Based on the disclosure and guiding principles of the foregoing specification, those skilled in the art are free to adjust and modify the above embodiments to optimize and improve their effects. Therefore, the scope of this invention is not limited to the specific embodiments explicitly shown; any reasonable improvements and variations should also be covered within the scope of this invention. Furthermore, although certain specific terms are used in this specification, these terms are only for convenience of explanation and communication and do not constitute any limitation on the actual application of this invention. This invention aims to provide an open and flexible solution for related technical fields, enabling practitioners to make appropriate adjustments and optimizations according to specific needs and actual circumstances.

Claims

1. A method for treating heavy metal stabilization red mud based on synergistic effects of multiple solid wastes, characterized in that: Four types of solid waste—coal mine soil, distiller's grains, acidic biochar, and garden soil—were used as stabilizers to reduce the water-extractable content of heavy metals in red mud through a multi-component combined addition method. The processing method is specifically carried out according to the following steps: (1) Soil pretreatment in coal mining areas: Soil from coal mining areas is dried at 55-65℃ until the moisture content is <5%, and then passed through a 1.5-2.5mm sieve to obtain pretreated soil from coal mining areas; (2) Garden soil pretreatment: Take garden soil and dry it at 55-65℃ until the moisture content is <5%, and pass it through a 1.5-2.5mm sieve to obtain pretreated garden soil; (3) Pretreatment of distiller's grains: Dry the distiller's grains at 55-65℃ until the moisture content is <5%, crush them and pass them through a 1.5-2.5mm sieve to obtain pretreated distiller's grains; (4) Preparation of acidic biochar: Rice husks are passed through a 1.5-2.5 mm sieve and then immersed in a 0.1 mol / L ferrous sulfate solution and left to stand for 7-9 h. The ratio of rice husks to 0.1 mol / L ferrous sulfate solution is 0.8-1.2 g: 8-12 mL to obtain pretreated rice husks. The pretreated rice husks are dried at 55-65℃ until the moisture content is <5%. Then, they are placed in a carbonization furnace and heated to 450-550℃ at a heating rate of 9-11℃ / min under nitrogen protection. The temperature is maintained at 450-550℃ for stable carbonization for 1.5-2.5 h. After heating is stopped, the experimental furnace is cooled to room temperature, and the furnace is opened to discharge the material to obtain acidic biochar. (5) Mixed curing and maturation: Take red mud and add 0.8-1.2wt% of pretreated coal mining soil, 0.8-1.2wt% of pretreated garden soil, 0.8-1.2wt% of pretreated distiller's grains and 0.8-1.2wt% of acidic biochar. Add deionized water and adjust the moisture content to 55-65%. Cure at 20-30℃ for 28-32 days to obtain heavy metal stabilized red mud.

2. The treatment method for heavy metal stabilization red mud based on multi-component solid waste synergy according to claim 1, characterized in that: In step (1), the soil from the coal mining area is dried at 60°C until the moisture content is <5%, and then passed through a 2mm sieve to obtain pretreated coal mining area soil; the total amount of iron and manganese oxides in the coal mining area soil is ≥7wt%, of which Fe2O3 is ≥5wt% and MnO2 is ≥2wt%.

3. The treatment method for heavy metal stabilization red mud based on multi-component solid waste synergy according to claim 1, characterized in that: In step (2), garden soil is dried at 60°C until the moisture content is <5%, and then passed through a 2mm sieve to obtain pretreated garden soil; the garden soil is topsoil with a plant growth history and contains organic matter ≥2wt%.

4. The treatment method for heavy metal stabilization red mud based on multi-component solid waste synergy according to claim 3, characterized in that: In step (2), the topsoil is taken from a location no less than 20cm below the ground surface.

5. The treatment method for heavy metal stabilization red mud based on multi-component solid waste synergy according to claim 1, characterized in that: In step (3), the lees are pretreated by drying the lees at 60°C until the moisture content is less than 5%, crushing them and passing them through a 2mm sieve to obtain pretreated lees.

6. The treatment method for heavy metal stabilization red mud based on multi-component solid waste synergy according to claim 1, characterized in that: In step (4), the preparation of acidic biochar is as follows: rice husks are passed through a 2mm sieve and then immersed in a 0.1mol / L ferrous sulfate solution and left to stand for 8 hours. The ratio of rice husks to 0.1mol / L ferrous sulfate solution is 1g:10mL, and pretreated rice husks are obtained. The pretreated rice husks were dried at 60℃ until the moisture content was <5%, and then placed in a carbonization furnace and heated to 500℃ at a heating rate of 10℃ / min under nitrogen protection. The temperature was maintained at 500℃ for stable carbonization for 2 hours. After heating was stopped, the experimental furnace was cooled to room temperature, and the furnace was opened to discharge the material, thus obtaining acidic biochar.

7. The treatment method for heavy metal stabilization red mud based on multi-component solid waste synergy according to claim 1, characterized in that: In step (5), the mixture is cured and matured: take red mud and add 1 wt% of pretreated coal mine soil, 1 wt% of pretreated garden soil, 1 wt% of pretreated distiller's grains and 1 wt% of acidic biochar to mix, add deionized water, adjust the moisture content to 60%, and cure at 25℃ for 30 days to obtain heavy metal stabilized red mud.

8. The treatment method for heavy metal stabilization red mud based on multi-component solid waste synergy according to any one of claims 1-7, characterized in that: The heavy metals include one or more of Al, As, Cd, Cr, Li, Ni, Pb, Sb, Sn, and V.

9. The application of heavy metal stabilized red mud according to any one of claims 1-8 in building materials, roadbed materials or soil conditioners.

Images