Iron tailing-based composite artificial soil as well as preparation method and application thereof

Abstract

The invention provides iron tailing-based composite artificial soil as well as a preparation method and application thereof. The artificial soil comprises an iron tailing-based porous aggregate and a functional compound component loaded on the iron tailing-based porous aggregate, the iron tailing-based porous aggregate has a three-dimensional network pore structure formed by mutually connecting fiber type pores and spherical pores in series. Through the synergistic effect of the porous aggregate and the functional compound component, the functions of water permeation, balance keeping and nutrient slow release are achieved, and the problems of iron tailing resource utilization, mine ecological restoration and degraded soil treatment are solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of solid waste resource utilization and soil remediation, and relates to an artificial soil, in particular to an iron tailings-based composite artificial soil and a preparation method and application thereof. BACKGROUND

[0002] With the acceleration of industrialization, the global iron ore mining volume is increasing year by year, and the resulting iron tailings have become one of the main industrial solid wastes. According to statistics, the global annual increase in iron tailings is as high as hundreds of millions of tons, and the stockpiled amount of iron tailings in China has exceeded ten billion tons. The long-term accumulation not only occupies a large amount of land resources, but also poses a serious threat to the ecological environment due to heavy metal seepage and dust pollution. The traditional treatment method of iron tailings is mainly landfill, but the landfill site has safety hazards such as dam breakage and leakage, and cannot realize resource utilization, which is contrary to the concept of current circular economy and green development.

[0003] At the same time, mining activities and intensive agricultural production have led to increasingly serious soil degradation problems, which are manifested in the loss of organic matter, heavy metal pollution, deterioration of pore structure, and imbalance of nutrients. In the existing soil remediation technology, physical remediation (such as thermal desorption) has high efficiency, but high-temperature treatment can easily damage the physical and chemical properties of the soil and is difficult to restore ecological functions; chemical remediation may introduce secondary pollution; and biological remediation has a long cycle and unstable effect.

[0004] In recent years, researchers have attempted to convert iron tailings into soil remediation materials or cultivation substrates, but their technical paths are mostly limited to simple physical compounding. For example, CN 102976867A discloses a production method of magnetized high-silicon iron tailings composite soil remediation fertilizer and the product, which specifically discloses that a magnetized high-silicon iron tailings is mixed with nitrogen, phosphorus and potassium fertilizer and heavy metal removal agent to prepare a remediation fertilizer. Although this method can improve the cation exchange capacity of the soil, the pore structure is single, the nutrient release rate is uncontrollable, and it is difficult to meet the needs of different crops or remediation scenarios. The existing technology generally ignores the synergistic relationship between the mineral composition of iron tailings and the regulation of pore structure, resulting in insufficient stability of the physical structure of the substrate, which is easily compacted in long-term use, and thus aggravates the deterioration of soil permeability.

[0005] Further analysis shows that iron tailings are rich in silicon, iron, aluminum oxides and clay minerals, and have the potential to build a porous structure, but existing processes cannot effectively activate the cementation activity or regulate the pore distribution. The nutrient release rate in the simply compounded substrate is low in matching degree with the plant demand, which easily causes nutrient loss or local high concentration, and thus inhibits plant growth.

[0006] In summary, it is of great practical significance and urgency to develop a technical method that can not only effectively treat industrial solid waste, but also prepare a substrate with excellent performance to solve the problems of mine ecological remediation and degraded soil remediation. SUMMARY

[0007] In view of the low utilization efficiency of iron tailings and the mismatch between the pore structure and nutrient supply of the traditional artificial soil, the present application aims to provide an iron tailings-based composite artificial soil and a preparation method and application thereof. The present application realizes the balance of water infiltration and retention and the slow-release function of nutrients through the synergistic effect of porous aggregates and functional complex components, thereby solving the problems of iron tailings utilization, mine ecological restoration and degraded soil treatment.

[0008] To achieve the object of the present application, the present application adopts the following technical solutions:

[0009] In a first aspect, the present application provides an iron tailings-based composite artificial soil, characterized in that the artificial soil comprises iron tailings-based porous aggregates and functional complex components loaded on the iron tailings-based porous aggregates.

[0010] The iron tailings-based porous aggregates have a three-dimensional network pore structure formed by the interconnection of fiber-type pores and spherical pores.

[0011] In the present application, the artificial soil has a three-dimensional network pore structure formed by the interconnection of fiber-type pores and spherical pores, which has adaptability to plant root growth (the fiber-type pores have a larger size for water and salt permeation, and the spherical pores have a smaller size for water retention and microbial parasitism). In addition, the surface and internal pores of the pore structure are loaded with functional complex components, which can be slowly released into the soil solution through ion exchange or desorption when the nutrient concentration in the soil is low, for plant absorption. This adsorption can maintain a relatively stable supply of nutrients in the soil, reduce nutrient loss and volatilization, better meet the needs of plant growth, and promote the restoration and improvement of the soil ecosystem.

[0012] In addition, the three-dimensional network pore structure of the artificial soil has strong structural and stability, which can improve the soil's resistance to erosion and compaction, and is beneficial to the growth of plant roots.

[0013] As a preferred technical solution of the present application, the specific surface area of the iron tailings-based porous aggregates is ≥15.4 m 2 / g, for example, it can be 15.4 m 2 / g, 15.5 m 2 / g, 15.6 m 2 / g, 15.7 m 2 / g, 15.8 m 2 / g or 15.9 m 2 / g, etc., but is not limited to the listed values, and other values not listed in the range are also applicable.

[0014] Preferably, the mass ratio of the functional complex component is 0.1-5% of the iron tailings-based porous aggregate, for example, it can be 0.1%, 1%, 2%, 3%, 4% or 5%, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0015] Preferably, the porosity of the three-dimensional network pore structure is 40-80%, for example, it can be 40%, 50%, 60%, 70% or 80%, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0016] Preferably, the average pore size of the three-dimensional network pore structure is 3 μm-5 mm, for example, it can be 3 μm, 10 μm, 100 μm, 500 μm, 1 mm, 2 mm, 3 mm, 4 mm or 5 mm, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0017] In a second aspect, the present application provides a preparation method of the iron tailings-based composite artificial soil as provided in the first aspect, and the preparation method comprises the following steps:

[0018] (1) mixing iron tailings, plant fibers, a foaming agent, an additive and water, stirring and then performing a forming treatment, and then sequentially performing a drying treatment and a heat treatment to obtain an iron tailings-based porous aggregate;

[0019] (2) immersing the iron tailings-based porous aggregate obtained in step (1) in a functional complex solution, performing ultrasonic treatment, and then sequentially performing solid-liquid separation and a drying treatment to obtain the iron tailings-based composite artificial soil.

[0020] In step (1) of the present application, a matrix skeleton (i.e., the iron tailings-based porous aggregate) having a three-dimensional network pore structure is formed by adjusting the pore-forming process, which cooperatively forms pores by combining a sacrificial template method and a foaming method. First, a foaming agent is used to generate foam by high-speed stirring to form spherical pores (foaming method pore-forming), and then plant fibers are used as templates, and after heat treatment, the plant fibers are pyrolyzed to form fiber-type pores (sacrificial template method pore-forming). The fiber-type pores are connected to each other to form a three-dimensional network pore structure.

[0021] As a preferred technical solution of the present application, the mass ratio of the iron tailings, plant fibers, foaming agent, additive and water in step (1) is 100:(0.5-10):(0.1-2):(5-20):(35-65), for example, it can be 100:5:1:10:45, 100:0.5:0.1:5:35, 100:8:1.4:16:60, 100:2.1:1.6:8:40 or 100:10:2:20:65, etc., but not limited to the listed values, other values not listed within the value range are also applicable.

[0022] Preferably, the D50 of the iron tailings is ≤10 μm, for example, it can be 10 μm, 9 μm, 8 μm, 7 μm, 6 μm or 5 μm, etc., but not limited to the listed values, other values not listed within the value range are also applicable.

[0023] Preferably, the iron tailings contain, in terms of mass percentage, the following elements: O 58.8-59.1 wt%, Si 14.4-14.8 wt%, Al 12.2-12.9 wt%, K 5.48-5.6 wt%, Fe 4.1-4.2 wt%, Mg 0.6-0.7 wt%, Ba 2.68-2.75 wt%, Ni 0.45-0.5 wt% and Ti 0.1-0.2 wt%.

[0024] For example, the content of O element in the iron tailings is 58.8-59.1 wt%, for example, it can be 58.8 wt%, 58.9 wt%, 59 wt% or 59.1 wt%, etc., but not limited to the listed values, other values not listed within the value range are also applicable;

[0025] The content of Si element in the iron tailings is 14.4-14.8 wt%, for example, it can be 14.4 wt%, 14.5 wt%, 14.6 wt%, 14.7 wt% or 14.8 wt%, etc., but not limited to the listed values, other values not listed within the value range are also applicable;

[0026] The content of Al element in the iron tailings is 12.2-12.9 wt%, for example, it can be 12.2 wt%, 12.4 wt%, 12.6 wt% or 12.9 wt%, etc., but not limited to the listed values, other values not listed within the value range are also applicable;

[0027] The content of K element in the iron tailings is 5.48-5.6 wt%, for example, it can be 5.48 wt%, 5.5 wt%, 5.54 wt%, 5.57 wt% or 5.6 wt%, etc., but not limited to the listed values, other values not listed within the value range are also applicable;

[0028] The content of Fe element in the iron tailings is 4.1-4.2wt%, for example, it can be 4.1wt%, 4.13wt%, 4.16wt% or 4.2wt%, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0029] The content of Mg element in the iron tailings is 0.6-0.7wt%, for example, it can be 0.6wt%, 0.63wt%, 0.66wt% or 0.6wt%, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0030] The content of Ba element in the iron tailings is 2.68-2.75wt%, for example, it can be 2.68wt%, 2.7wt%, 2.72wt% or 2.75wt%, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0031] The content of Ni element in the iron tailings is 0.45-0.5wt%, for example, it can be 0.45wt%, 0.46wt%, 0.48wt% or 0.5wt%, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0032] The content of Ti element in the iron tailings is 0.1-0.2wt%, for example, it can be 0.1wt%, 0.14wt%, 0.17wt% or 0.2wt%, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0033] Preferably, the plant fiber includes any one or a combination of at least two of rice straw fiber, wheat straw fiber, straw fiber, coconut palm fiber, reed fiber, bamboo fiber or cotton fiber, and a typical but non-limiting combination includes a combination of rice straw fiber, wheat straw fiber and straw fiber, a combination of reed fiber, bamboo fiber and cotton fiber, a combination of coconut palm fiber, reed fiber and bamboo fiber, or a combination of rice straw fiber, wheat straw fiber, straw fiber, coconut palm fiber, reed fiber, bamboo fiber and cotton fiber.

[0034] Preferably, the fiber length of the plant fiber is 0.1-50mm, for example, it can be 0.1mm, 5mm, 10mm, 20mm, 30mm, 40mm or 50mm, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0035] Preferably, the foaming agent includes sodium ethoxylated alkyl sulfate and a non-ionic surfactant.

[0036] Preferably, the non-ionic surfactant comprises any one or a combination of at least two of coconut oil fatty acid diethanolamide, fatty alcohol polyoxyethylene ether or fatty acid polyoxyethylene ester, typically but not limitedly, the combination comprises coconut oil fatty acid diethanolamide and fatty alcohol polyoxyethylene ether, coconut oil fatty acid diethanolamide and fatty acid polyoxyethylene ester, or coconut oil fatty acid diethanolamide, fatty alcohol polyoxyethylene ether and fatty acid polyoxyethylene ester.

[0037] Preferably, the content of sodium ethoxylated alkyl sulfate in the foaming agent is 50-80 wt%, for example, it can be 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt% or 80 wt%, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0038] Preferably, the content of non-ionic surfactant in the foaming agent is 0-50 wt%, for example, it can be 5 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt% or 50 wt%, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0039] In the foaming agent of step (1) of the present application, the sodium ethoxylated alkyl sulfate has excellent high foaming capacity and can produce a large amount of fine and small bubbles; when the non-ionic surfactant such as coconut oil fatty acid diethanolamide is used, the produced bubbles can be more stable and produce bubbles of medium size; the combination of fine and medium size bubbles can construct a porous structure similar to soil aggregates; the combination of the two through functional complementation and synergistic effect realizes more flexible foaming control and can obtain fine, stable, synergistic and rich spherical bubbles of different sizes.

[0040] Preferably, the additive comprises clay and a sintering aid.

[0041] Preferably, the sintering aid comprises a combination of at least two of sodium carbonate, calcium fluoride or boron mud, typically but not limitedly, the combination comprises sodium carbonate and calcium fluoride, sodium carbonate and boron mud, calcium fluoride and boron mud, or sodium carbonate, calcium fluoride and boron mud.

[0042] Preferably, the content of clay in the additive is 30-60 wt%, for example, it can be 30 wt%, 40 wt%, 50 wt% or 60 wt%, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0043] Preferably, the content of sodium carbonate in the additive is 0-40wt%, for example, it can be 0wt%, 10wt%, 20wt%, 30wt% or 40wt%, etc., but not limited to the listed values, other values not listed in the value range are also applicable.

[0044] Preferably, the content of calcium fluoride in the additive is 0-25wt%, for example, it can be 0wt%, 5wt%, 10wt%, 15wt%, 20wt% or 25wt%, etc., but not limited to the listed values, other values not listed in the value range are also applicable.

[0045] Preferably, the content of boron mud in the additive is 0-70wt%, for example, it can be 0wt%, 10wt%, 30wt%, 50wt% or 70wt%, etc., but not limited to the listed values, other values not listed in the value range are also applicable.

[0046] The additive of step (1) of the present application can increase the viscosity of the foaming system while having a foam stabilizing effect; in addition, the additive can increase the initial strength of the green body after the forming process, providing a basic strength for demolding; further, the present application can further reduce the temperature of heat treatment by mixing the use of clay and sintering aid, reduce the heat treatment time; reduce the phenomenon of cracking or deformation of porous agglomerates, reduce the defects of the body.

[0047] Preferably, the stirring speed of step (1) is 500-1500rpm, for example, it can be 500rpm, 700rpm, 900rpm, 1100rpm, 1300rpm or 1500rpm, etc., but not limited to the listed values, other values not listed in the value range are also applicable.

[0048] Preferably, the stirring time of step (1) is 2-30min, for example, it can be 2min, 5min, 10min, 15min, 20min, 25min or 30min, etc., but not limited to the listed values, other values not listed in the value range are also applicable.

[0049] In the present application, high-speed stirring produces dense and fine foam, thereby forming spherical pores; if the stirring speed is too slow, the amount of bubble generation will be reduced, and the bubble size is not uniform, and the surfactant is not fully functional; if the stirring speed is too fast, it will lead to a decrease in foam stability, liquid splashing or foam overflow, and increased energy consumption.

[0050] Preferably, the forming process of step (1) includes drop granulation or injection molding.

[0051] Preferably, the drying treatment in step (1) has a temperature of 50-120℃, for example, it can be 50℃, 60℃, 80℃, 100℃ or 120℃, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0052] Preferably, the drying treatment in step (1) has a time of 2-6h, for example, it can be 2h, 3h, 4h, 5h or 6h, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0053] In the present application, the drying treatment is used to remove excess moisture, form an initial bonding strength, and facilitate demolding. If the temperature of the drying treatment is too high, the moisture will be lost too quickly, the upper layer will dry too quickly, and the shrinkage difference between the upper and lower layers will be large, which can cause the product to crack, defoam, and even cause the surfactant to fail. If the temperature of the drying treatment is too low, the strength will develop slowly, the structure will be uneven, which will affect the surface flatness, and it can also defoam.

[0054] Preferably, the heat treatment in step (1) has a temperature of 500-1000℃, for example, it can be 500℃, 600℃, 700℃, 800℃, 900℃ or 1000℃, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0055] Preferably, the heat treatment in step (1) has a time of 0.5-6h, for example, it can be 0.5h, 1h, 2h, 3h, 4h, 5h or 6h, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0056] In the present application, pyrolysis of plant fibers is achieved through heat treatment, thereby forming fiber-type pores. If the temperature of the heat treatment is too high, the material will be sintered excessively, the porosity will decrease, the activity will decrease, and the surface area will decrease. If the temperature of the heat treatment is too low, the strength will not be enough, and even the plant fibers will not be decomposed, and effective through pores will not be formed.

[0057] As a preferred technical solution of the present application, the preparation raw materials of the functional compound solution in step (2) include organic matter, fertilizer, trace element chelate and microbial derivative.

[0058] In the present application, the microbial derivative in the functional compound solution can secrete organic acids, enzymes and other substances during growth and reproduction. These substances can chemically react with the nutrients in the fertilizer, helping to dissolve and release the nutrients in the functional compound solution, and promoting nutrient cycling.

[0059] Preferably, the content of organic matter in the functional compound solution is 50-70wt%, for example, it can be 50wt%, 55wt%, 60wt%, 65wt% or 70wt%, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0060] Preferably, the organic matter includes any one or a combination of at least two of humic acid, biogas residue or sawdust, and a typical but non-limiting combination includes a combination of humic acid and biogas residue, a combination of humic acid and sawdust, a combination of biogas residue and sawdust, or a combination of humic acid, biogas residue and sawdust.

[0061] Preferably, the content of fertilizer in the functional compound solution is 20-40wt%, for example, it can be 20wt%, 25wt%, 30wt%, 35wt% or 40wt%, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0062] Preferably, the fertilizer includes slow-release nitrogen, phosphorus and potassium compound fertilizer.

[0063] Preferably, the content of trace elements in the functional compound solution is 5-10wt%, for example, it can be 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt%, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0064] Preferably, the trace elements include any one or a combination of at least two of iron, zinc, boron, copper, manganese or selenium, and a typical but non-limiting combination includes a combination of iron, zinc, boron and manganese, a combination of zinc, boron, copper, manganese and selenium, a combination of iron, zinc and boron, or a combination of iron, zinc, boron, copper, manganese and selenium.

[0065] It is worth noting that the specific type of trace element chelate in the present application is not limited, as long as it can provide the corresponding trace element.

[0066] Preferably, the content of microbial derivatives in the functional compound solution is 0.1-0.5wt%, for example, it can be 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt% or 0.5wt%, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0067] Preferably, the microbial derivative includes a microbial strain or a metabolite.

[0068] Preferably, the microbial strain includes nitrogen-fixing bacteria and / or phosphorus-dissolving bacteria.

[0069] It is worth mentioning that the metabolite of the present application is specifically the metabolite of a microbial strain, and more specifically, the metabolite of the nitrogen-fixing bacteria includes ammonia, organic acids, polysaccharide substances and plant hormone substances; the metabolite of the phosphorus-solubilizing bacteria includes organic acids, phosphatase, siderophores and antibiotics or bacteriostatic substances.

[0070] More specifically, the microbial derivative can provide various nutrients for the soil, achieve the dissolution of insoluble minerals, improve the soil structure, inhibit the growth of harmful microorganisms in the soil, and promote the growth and development of plant roots.

[0071] As a preferred technical solution of the present application, the ultrasonic treatment time in step (2) is 2-20 min, for example, it can be 2 min, 5 min, 10 min, 15 min or 20 min, etc., but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0072] Preferably, the power of the ultrasonic treatment in step (2) is 380-1200 W, for example, it can be 380 W, 500 W, 800 W, 1000 W or 1200 W, etc., but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0073] Preferably, the temperature of the drying treatment in step (2) is 20-80℃, for example, it can be 20℃, 40℃, 60℃ or 80℃, etc., but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0074] In the present application, the purpose of the drying treatment is to remove excess water, form the initial bonding strength of the artificial soil, and facilitate demolding; if the temperature of the drying treatment is too high, it will cause the water to evaporate too quickly, the upper layer to dry too quickly, and the shrinkage difference between the upper and lower layers to be large, causing the product to crack, defoaming, and possibly causing the surfactant to fail, affecting the overall pore structure; on the contrary, if the temperature is too low, it will cause the strength of the artificial soil to develop slowly, the structure to be uneven, affecting the surface flatness, and possibly causing defoaming.

[0075] Preferably, the end point of the drying treatment in step (2) is that the water content of the iron tailings-based composite artificial soil is ≤10wt%, for example, it can be 10wt%, 8wt%, 6wt%, 4wt% or 2wt%, etc., but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0076] The water content of the iron tailings-based composite artificial soil of the present application is not higher than 10wt%, and the reason is that if the water content is too high, a large amount of water vapor will evaporate during heat treatment, causing the product to crack and affecting the pore structure and product integrity.

[0077] As a preferred technical solution of the present application, the preparation method of the iron tailings-based composite artificial soil provided by the second aspect of the present application comprises the following steps:

[0078] (1) mixing the iron tailings, plant fibers, foaming agent, additives and water in a mass ratio of 100:(0.5-10):(0.1-2):(5-20):(35-65), stirring for 2-30 min under the condition of 500-1500 rpm, and then performing a molding treatment, and then performing a drying treatment at 50-120℃ for 2-6 h, and then performing a heat treatment at 500-1000℃ for 0.5-6 h, to obtain the iron tailings-based porous aggregate;

[0079] The fiber length of the plant fibers is 0.1-50 mm.

[0080] The foaming agent comprises sodium ethoxylated alkyl sulfate and non-ionic surfactant; the content of the sodium ethoxylated alkyl sulfate in the foaming agent is 50-80 wt%, and the content of the non-ionic surfactant is 0-50 wt%; the non-ionic surfactant comprises any one or a combination of at least two of coconut oil fatty acid diethanolamide, fatty alcohol polyoxyethylene ether or fatty acid polyoxyethylene ester.

[0081] The additives comprise clay and sintering aid; the sintering aid comprises a combination of at least two of sodium carbonate, calcium fluoride or boron mud; the content of the clay in the additives is 30-60 wt%, the content of the sodium carbonate is 0-40 wt%, the content of the calcium fluoride is 0-25 wt%, and the content of the boron mud is 0-70 wt%.

[0082] (2) immersing the iron tailings-based porous aggregate obtained in step (1) in a functional compound liquid, performing ultrasonic treatment for 2-20 min, and then performing solid-liquid separation, and then performing a drying treatment at 20-80℃ until the water content is ≤10 wt%, to obtain the iron tailings-based composite artificial soil.

[0083] The preparation raw materials of the functional compound liquid comprise organic matter, fertilizer, trace element chelate and microbial derivative.

[0084] The content of the organic matter in the functional compound liquid is 50-70 wt%, the content of the fertilizer is 20-40 wt%, the content of the trace element is 5-10 wt%, and the content of the microbial derivative is 0.1-0.5 wt%.

[0085] In the third aspect, the present application provides an application of the iron tailings-based composite artificial soil provided by the first aspect, and the iron tailings-based composite artificial soil is used for repairing soil or cultivating green plants.

[0086] Preferably, the soil remediation includes any one of mine ecological remediation, saline-alkali soil remediation or hardening soil remediation.

[0087] More specifically, the mine ecological remediation is to improve the soil structure of the mine by using the iron tailings-based composite artificial soil to promote the growth of vegetation, so as to realize the remediation and reconstruction of the ecological environment of the mine.

[0088] The saline-alkali soil remediation or hardening soil remediation is to adjust the soil pH value, break the soil hardening, improve the soil aeration, water permeability and water retention, etc. by mixing the iron tailings-based composite artificial soil, so as to increase the flow of water and salt, improve the physicochemical properties of the saline-alkali soil or hardening soil, and improve the soil fertility.

[0089] The cultivated green plants are to use the iron tailings-based composite artificial soil as the urban greening cultivation substrate, provide rich nutrients and good root adhesion environment for plants, meet the growth needs of urban greening plants, and improve the urban greening effect.

[0090] The numerical range in the present application includes not only the point values exemplified above, but also any point values between the above numerical ranges that are not exemplified, and the specific point values included in the range are not listed in the present application due to the length and the consideration of simplicity.

[0091] Compared with the prior art, the present application has the following beneficial effects:

[0092] (1) The iron tailings-based composite artificial soil provided by the present application uses industrial solid waste iron tailings as the main raw material, realizes the large-scale consumption of iron tailings, reduces the cost, and at the same time improves the resource utilization rate, has significant economic and environmental benefits;

[0093] (2) The iron tailings-based composite artificial soil provided by the present application has a three-dimensional network pore structure, which can improve the porosity of the soil when added to the soil, increase the aeration and water permeability of the soil, make the soil more loose, be beneficial to the respiration and growth of plant roots, make the soil more suitable for plant root penetration and growth and development, and the effect of improving the aeration is more significant compared with traditional improvers;

[0094] (3) The iron tailings-based composite artificial soil provided by the present application is loaded with functional complex components, which can be slowly released into the soil solution through ion exchange or desorption when the nutrient concentration in the soil is low, so as to ensure the relative stability of the nutrient supply in the soil, reduce the loss and volatilization of the nutrient, better meet the growth needs of plants, and promote the recovery and improvement of the soil ecosystem;

[0095] (4) The iron tailings-based composite artificial soil has strong structural property and stability, and use of the soil can improve the soil's ability to resist erosion and hardening, and is beneficial to the growth of plant roots;

[0096] (5) The preparation method of the iron tailings-based composite artificial soil is simple in process, convenient to operate, suitable for large-scale production, and beneficial to popularization and application. BRIEF DESCRIPTION OF DRAWINGS

[0097] Figure 1 A cross-sectional view of the iron tailings-based composite artificial soil provided in Embodiment 1 of the present application;

[0098] Figure 2 A schematic diagram of a three-dimensional network pore structure model of the iron tailings-based composite artificial soil provided in Embodiment 1 of the present application. DETAILED DESCRIPTION

[0099] The technical solutions of the present application will be further described through specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations on the present application.

[0100] The sodium ethoxylated alkyl sulfate used in the following examples and comparative examples is purchased from Jinan Sirui Chemical Co., Ltd.; the nitrogen-fixing bacteria can produce auxins such as amino acids and indole acetic acid; the metabolic products of the phosphorus-solubilizing bacteria include organic acids, phosphatase auxins, cytokinins, and gibberellins.

[0101] In the following examples and comparative examples, the iron tailings used include the following elements in mass percentage: O 59.02 wt%, Si 14.63 wt%, Al 12.66 wt%, K 5.52 wt%, Fe 4.15 wt%, Mg 0.67 wt%, Ba 2.72 wt%, Ni 0.48 wt%, and Ti 0.15 wt%.

[0102] Example 1

[0103] The present embodiment provides an iron tailings-based composite artificial soil, which includes an iron tailings-based porous aggregate and a functional compound component loaded on the iron tailings-based porous aggregate.

[0104] The iron tailings-based porous aggregate has a three-dimensional network pore structure formed by interconnection of fiber-type pores and spherical pores.

[0105] The specific surface area of the iron tailings-based porous aggregate is 18.6 m 2 / g; the mass percentage of the functional compound component is 2.5% of the iron tailings-based porous aggregate; the porosity of the three-dimensional network pore structure is 60%; and the average pore diameter of the three-dimensional network pore structure is 1.2 mm.

[0106] A profile of the iron tailings-based composite artificial soil is shown in Figure 1 Figure 2 A three-dimensional network pore structure model is shown in

[0107] The preparation method of the iron tailings-based composite artificial soil comprises the following steps:

[0108] (1) mixing iron tailings, plant fibers (rice straw fibers), foaming agents, additives and water in a mass ratio of 100:5:1.2:17.5:50, stirring at 1000 rpm for 15 min, and then performing a molding process, and then performing a drying process at 80℃ for 4 h, and then performing a heat treatment at 750℃ for 3 h to obtain iron tailings-based porous agglomerates;

[0109] The fiber length of the plant fibers is 25 mm.

[0110] The foaming agent comprises sodium ethoxylated alkyl sulfate and a non-ionic surfactant; the content of sodium ethoxylated alkyl sulfate in the foaming agent is 75wt%, and the content of the non-ionic surfactant is 25wt%; the non-ionic surfactant comprises fatty alcohol polyoxyethylene ether and fatty acid polyoxyethylene ester in a mass ratio of 1:1.

[0111] The additives comprise clay and sintering aids; the sintering aids comprise sodium carbonate, calcium fluoride and boron mud; the content of clay in the additives is 55wt%, the content of sodium carbonate is 20wt%, the content of calcium fluoride is 10wt%, and the content of boron mud is 15wt%.

[0112] (2) immersing the iron tailings-based porous agglomerates obtained in step (1) in a functional compound liquid, performing ultrasonic treatment for 15 min, and then performing solid-liquid separation, and then performing a drying process at 50℃ until the water content is ≤8wt% to obtain the iron tailings-based composite artificial soil.

[0113] The preparation raw materials of the functional compound liquid comprise organic matter, fertilizer, trace element chelate and microbial derivative.

[0114] The content of organic matter in the functional compound liquid is 60wt%, the content of fertilizer is 30wt%, the content of trace elements is 9.75wt%, and the content of microbial derivative is 0.25wt%; the organic matter is humic acid, the fertilizer is slow-release nitrogen, phosphorus and potassium compound fertilizer, the trace elements are iron, zinc and boron, and the microbial derivative is phosphorus-solubilizing bacteria.

[0115] Example 2

[0116] ​The embodiment provides an iron tailing-based composite artificial soil, which comprises an iron tailing-based porous aggregate and a functional compound component loaded on the iron tailing-based porous aggregate.

[0117] The iron tailing-based porous aggregate has a three-dimensional network pore structure formed by interconnection of fiber type pores and spherical pores.

[0118] The specific surface area of the iron tailing-based porous aggregate is 15.4 m 2 / g; the mass percentage of the functional compound component is 0.1% of the iron tailing-based porous aggregate; the porosity of the three-dimensional network pore structure is 40%; and the average pore diameter of the three-dimensional network pore structure is 5 mm.

[0119] The preparation method of the iron tailing-based composite artificial soil comprises the following steps:

[0120] (1) mixing iron tailing, plant fiber, foaming agent, additive and water at a mass ratio of 100:0.5:0.1:5:35, stirring at 500 rpm for 30 min, and then performing molding treatment, and then performing drying treatment at 50 DEG C for 6 h, and then performing heat treatment at 500 DEG C for 6 h to obtain the iron tailing-based porous aggregate;

[0121] The fiber length of the plant fiber is 50 mm.

[0122] The foaming agent comprises sodium ethoxylated alkyl sulfate and non-ionic surfactant; the content of sodium ethoxylated alkyl sulfate in the foaming agent is 50 wt%, and the content of non-ionic surfactant is 50 wt%; the non-ionic surfactant comprises fatty alcohol polyoxyethylene ether, fatty acid polyoxyethylene ester and coconut oil fatty acid diethanolamide at a mass ratio of 1:1:1.

[0123] The additive comprises clay and sintering aid; the sintering aid comprises sodium carbonate and boron mud; the content of clay in the additive is 30 wt%, the content of sodium carbonate is 40 wt%, and the content of boron mud is 30 wt%.

[0124] (2) immersing the iron tailing-based porous aggregate obtained in step (1) in a functional compound liquid, performing ultrasonic treatment for 2 min, then performing solid-liquid separation, and then performing drying treatment at room temperature until the water content is less than or equal to 10 wt% to obtain the iron tailing-based composite artificial soil.

[0125] The preparation raw material of the functional compound liquid comprises organic matter, fertilizer, trace element chelate and microbial derivative.

[0126] The content of the organic matter in the functional compound liquid is 70 wt%, the content of the fertilizer is 22.9 wt%, the content of the trace elements is 7 wt%, and the content of the microbial derivative is 0.1 wt%; the organic matter is biogas residue, the fertilizer is slow-release nitrogen, phosphorus and potassium compound fertilizer, the trace elements are iron, zinc, boron, copper, manganese and selenium, and the microbial derivative is nitrogen-fixing bacteria.

[0127] Embodiment 3

[0128] The embodiment provides an iron tailings-based composite artificial soil, which comprises an iron tailings-based porous aggregate and a functional compound component loaded on the iron tailings-based porous aggregate.

[0129] The iron tailings-based porous aggregate has a three-dimensional network pore structure formed by the fiber type pores and the spherical pores in series.

[0130] The specific surface area of the iron tailings-based porous aggregate is 16.7 m 2 / g; the mass ratio of the functional compound component to the iron tailings-based porous aggregate is 5%; the porosity of the three-dimensional network pore structure is 80%; and the average pore diameter of the three-dimensional network pore structure is 3 μm.

[0131] The preparation method of the iron tailings-based composite artificial soil comprises the following steps:

[0132] (1) mixing iron tailings, plant fibers, a foaming agent, an additive and water at a mass ratio of 100:10:2:20:65, stirring at 1500 rpm for 2 min, and then performing a molding treatment, and then performing a drying treatment at 120°C for 2 h, and then performing a heat treatment at 1000°C for 0.5 h to obtain an iron tailings-based porous aggregate;

[0133] The fiber length of the plant fibers is 0.1 mm.

[0134] The foaming agent comprises sodium ethoxylated alkyl sulfate and a non-ionic surfactant; the content of the sodium ethoxylated alkyl sulfate in the foaming agent is 80 wt%, and the content of the non-ionic surfactant is 20 wt%; and the non-ionic surfactant is a fatty alcohol polyoxyethylene ether.

[0135] The additive comprises clay and a sintering aid; the sintering aid comprises calcium fluoride and boron mud; the content of the clay in the additive is 60 wt%, the content of the calcium fluoride is 20 wt%, and the content of the boron mud is 20 wt%.

[0136] (2) impregnating the iron tailing-based porous aggregate obtained in step (1) in a functional compound liquid, performing ultrasonic treatment for 20 min, then performing solid-liquid separation, and then performing drying treatment at 80 DEG C until the water content is less than or equal to 5 wt%, to obtain the iron tailing-based composite artificial soil;

[0137] The preparation raw materials of the functional compound liquid include organic matter, fertilizer, trace element chelate and microbial derivative.

[0138] The content of the organic matter in the functional compound liquid is 50 wt%, the content of the fertilizer is 39.5 wt%, the content of the trace element is 10 wt%, and the content of the microbial derivative is 0.5 wt%. The organic matter is sawdust, the fertilizer is slow-release nitrogen, phosphorus and potassium compound fertilizer, the trace element is iron, zinc and boron, and the microbial derivative is phosphorus-solubilizing bacteria.

[0139] Example 4

[0140] This embodiment provides an iron tailing-based composite artificial soil, which is the same as that in Example 1.

[0141] The preparation method of the iron tailing-based composite artificial soil is different from that in Example 1 only in that:

[0142] In this embodiment, the foaming agent in step (1) is adjusted to be sodium ethoxylated alkyl sulfate.

[0143] Example 5

[0144] This embodiment provides an iron tailing-based composite artificial soil, which is the same as that in Example 1.

[0145] The preparation method of the iron tailing-based composite artificial soil is different from that in Example 1 only in that:

[0146] In this embodiment, the foaming agent in step (1) is adjusted to be non-ionic surfactant.

[0147] Example 6

[0148] This embodiment provides an iron tailing-based composite artificial soil, which is the same as that in Example 1.

[0149] The preparation method of the iron tailing-based composite artificial soil is different from that in Example 1 only in that:

[0150] In this embodiment, the sintering aid in the additive in step (1) is adjusted to be clay of equal mass.

[0151] Example 7

[0152] The present example provides an iron tailings-based composite artificial soil, which is the same as that of Example 1.

[0153] The preparation method of the iron tailings-based composite artificial soil is different from that of Example 1 only in that:

[0154] In the present example, the clay in the additive of step (1) is adjusted to boron mud of equal mass.

[0155] Example 8

[0156] The present example provides an iron tailings-based composite artificial soil, which is the same as that of Example 1.

[0157] The preparation method of the iron tailings-based composite artificial soil is different from that of Example 1 only in that:

[0158] In the present example, the stirring speed of step (1) is adjusted to 300 rpm.

[0159] Example 9

[0160] The present example provides an iron tailings-based composite artificial soil, which is the same as that of Example 1.

[0161] The preparation method of the iron tailings-based composite artificial soil is different from that of Example 1 only in that:

[0162] In the present example, the stirring speed of step (1) is adjusted to 1800 rpm.

[0163] Example 10

[0164] The present example provides an iron tailings-based composite artificial soil, which is the same as that of Example 1.

[0165] The preparation method of the iron tailings-based composite artificial soil is different from that of Example 1 only in that:

[0166] In the present example, the temperature of the heat treatment of step (1) is adjusted to 300℃.

[0167] Example 11

[0168] The present example provides an iron tailings-based composite artificial soil, which is the same as that of Example 1.

[0169] The preparation method of the iron tailings-based composite artificial soil is different from that of Example 1 only in that:

[0170] In the present example, the temperature of the heat treatment of step (1) is adjusted to 1200℃.

[0171] Example 12

[0172] The present example provides an iron tailings-based composite artificial soil, which is the same as that of Example 1.

[0173] The preparation method of the iron tailings-based composite artificial soil differs from that of Example 1 only in that:

[0174] In the present example, the temperature of the drying treatment in step (2) is adjusted to 100°C.

[0175] Example 13

[0176] The present example provides an iron tailings-based composite artificial soil, which is the same as that of Example 1.

[0177] The preparation method of the iron tailings-based composite artificial soil differs from that of Example 1 only in that:

[0178] In the present example, the end point of the drying treatment in step (2) is adjusted to a water content of the iron tailings-based composite artificial soil of 15 wt.%.

[0179] Comparative Example 1

[0180] The present comparative example provides an iron tailings-based composite artificial soil, which differs from that of Example 1 only in that:

[0181] The iron tailings-based porous agglomerates in the iron tailings-based composite artificial soil of the present comparative example only have fiber-type pores.

[0182] The specific surface area of the iron tailings-based porous agglomerates in the present comparative example is 14.9 m 2 / g; the mass ratio of the functional complex component is 2.5% of the iron tailings-based porous agglomerates; the porosity of the three-dimensional network pore structure is 60%; and the average pore diameter of the three-dimensional network pore structure is 3.8 mm.

[0183] The preparation method of the iron tailings-based composite artificial soil differs from that of Example 1 only in that:

[0184] In the present comparative example, step (1) is adjusted to mixing iron tailings, plant fibers (rice straw fibers), additives, and water at a mass ratio of 100:5:17.5:50, stirring at 200 rpm for 15 min, and then performing a molding treatment, followed by drying treatment at 80°C for 4 h, and then heat treatment at 750°C for 3 h to obtain iron tailings-based porous agglomerates; that is, the present comparative example omits the foaming agent and reduces the stirring speed.

[0185] Comparative Example 2

[0186] The comparative example provides an iron tailings-based composite artificial soil, which is only different from example 1 in that:

[0187] The specific surface area of the iron tailings-based porous aggregate in the comparative example is 12.3 m 2 / g; the mass ratio of the functional compound component is 2.5% of the iron tailings-based porous aggregate; the porosity of the three-dimensional network pore structure is 45%; and the average pore diameter of the three-dimensional network pore structure is 2.9 mm.

[0188] The iron tailings-based porous aggregate in the iron tailings-based composite artificial soil of the comparative example only has spherical pores.

[0189] The preparation method of the iron tailings-based composite artificial soil is only different from example 1 in that:

[0190] The comparative example omits the plant fiber in step (1).

[0191] Comparative example 3

[0192] The comparative example provides an iron tailings-based composite artificial soil, which is only different from example 1 in that:

[0193] The comparative example omits the functional compound component loaded on the iron tailings-based porous aggregate.

[0194] The preparation method of the iron tailings-based composite artificial soil is only different from example 1 in that:

[0195] The comparative example omits step (2).

[0196] Application example 1

[0197] The iron tailings-based composite artificial soil provided by the above examples and comparative examples is used as an urban greening cultivation substrate to plant seedlings, and the water absorption, water permeability, and plant coverage of the soil are observed in the order of 1 month, 3 months, 6 months, and 12 months after planting the seedlings, and the results are shown in Table 1.

[0198] The determination method of the water absorption includes: placing m1 (g) of dry iron tailings-based composite artificial soil sample into deionized water, standing for 30 min, and after being saturated with water, filtering the remaining aqueous solution with a screen, and then transferring the sample to a container to weigh the mass m2 (g) after water absorption, the water absorption rate Q = (m2-m1) / m1x100%;

[0199] The determination method of the water permeability includes: under a normal temperature environment (20℃), a pressure range of 0.01-0.05 MPa (a filtration area of 11.95 cm 2The pure water permeation flux was determined under the condition that the sample thickness was 8.5 mm, and the test was carried out after each pressure was kept for 3 min to reach a steady state, and the calculation formula of the permeation flux was as follows:

[0200] J=q / (Sσ)

[0201] In the formula, J is the pure water permeation flux (m 3 ·m -2 ·h -1 ), q is the pure water permeation volume (m 3 ), S is the effective permeation area of pure water (m 2 ), and σ is the permeation time (h).

[0202] Application Example 2

[0203] The tailing-based composite artificial soil provided in the above examples and comparative examples was used for the remediation of hardened soil, and the remediation method included: covering or mixing the tailing-based composite artificial soil provided in the above examples and comparative examples in the hardened soil to carry out soil remediation.

[0204] The soil porosity of the hardened soil to be remediated was ≤40%; after remediation for 15 days, the soil porosity was detected, and the results are shown in Table 1.

[0205] Application Example 3

[0206] The tailing-based composite artificial soil provided in the above examples and comparative examples was used for the ecological remediation of a mine at a mixing amount of 10-30 wt%;

[0207] In the formula, the density of the soil in the mine before remediation was ≥1.67 g / m 3 After remediation for 15 days, the density of the soil in the mine was detected, and the results are shown in Table 1.

[0208] Table 1

[0209]

[0210]

[0211] According to Table 2, the following points can be known:

[0212] (1) According to the comprehensive analysis of Examples 1-3, the artificial soil provided by the application has excellent strong structural properties and stability, and the application can improve the ability of the soil to resist erosion and hardening, and is beneficial to the growth of plant root systems;

[0213] (2) According to the comprehensive analysis of Example 1 and Examples 4-5, the selection of the foaming agent in the preparation process will affect the three-dimensional pore structure of the artificial soil.

[0214] If only ethoxylated alkyl sodium sulfate or nonionic surfactant is used as a foaming agent, it will result in single foam size and poor stability, and it is difficult to build a stable three-dimensional network pore structure.

[0215] (3) According to the comprehensive analysis of examples 1 and examples 6-7, the selection of the additive components will affect the stability of the foaming system and the initial strength of the green body; if only clay is used as an additive, it is difficult to achieve excellent bubble stability and poor demolding strength;

[0216] (4) According to the comprehensive analysis of examples 1 and examples 8-9, the stirring speed will affect the foaming process; if the stirring speed is too low, it will result in less bubble generation, uneven bubble size, and insufficient surfactant effect; if the stirring speed is too high, it will result in decreased foam stability; all of which cannot build a stable three-dimensional network pore structure, thereby affecting the performance of the artificial soil;

[0217] (5) According to the comprehensive analysis of examples 1 and examples 10-11, the temperature of heat treatment will affect the stability of the three-dimensional pore structure; if the temperature of heat treatment is too high, it will result in excessive sintering of the material, less pore, reduced activity, and reduced surface area; if the temperature of heat treatment is too low, it will result in slow strength development, uneven structure, and affected surface flatness;

[0218] (6) According to the comprehensive analysis of examples 1 and examples 12-13, if the temperature of the drying process described in step (2) is too high, it will result in rapid water loss, rapid drying of the upper layer, large shrinkage difference between the upper and lower layers, product cracking, defoaming, and surfactant failure, thereby affecting the overall pore structure; if the water content in the artificial soil is too low, it will result in slow strength development and uneven structure affecting surface flatness;

[0219] (7) According to the comprehensive analysis of examples 1 and comparative examples 1-2, compared with the artificial soil with two types of pores in example 1, omitting any one of the pore structures will reduce the specific surface area of the porous aggregate, thereby reducing the functional complex components loaded thereon, and further resulting in the inability of the artificial soil to complete the synergistic effect of multiple functions;

[0220] (8) According to the comprehensive analysis of examples 1 and comparative example 3, omitting the functional complex components will affect the composite effect of soil improvement, limit the comprehensive improvement effect, and cannot complete the synergistic effect of water permeation / retention and soil microenvironment improvement.

[0221] In summary, through the synergistic effect of the porous aggregate and the functional complex components, the present application realizes the balance of water penetration and retention and the function of nutrient slow release, and solves the problems of resource utilization of iron tailings, ecological restoration of mines, and treatment of degraded soil.

[0222] The applicant states that the above description is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and it should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought out by those skilled in the art, and all of them fall within the protection scope and disclosure scope of the present application.

Claims

1. A composite artificial soil based on iron tailings, characterized in that, The artificial soil includes iron tailings-based porous aggregates and functional compound components loaded on the iron tailings-based porous aggregates. The iron tailings-based porous agglomerates have a three-dimensional network pore structure composed of interconnected fibrous pores and spherical pores.

2. The iron tailings-based composite artificial soil according to claim 1, characterized in that, The specific surface area of ​​the iron tailings-based porous agglomerates is ≥15.4 m². 2 / g; Preferably, the mass percentage of the functional compound component is 0.1% to 5% of the iron tailings-based porous agglomerate.

3. The iron tailings-based composite artificial soil according to claim 1, characterized in that, The porosity of the three-dimensional network pore structure is 40-80%; Preferably, the average pore size of the three-dimensional network pore structure is 3μm to 5mm.

4. A method for preparing iron tailings-based composite artificial soil as described in any one of claims 1-3, characterized in that, The preparation method includes the following steps: (1) Mix iron tailings, plant fiber, foaming agent, additives and water, stir and then shape them, and then dry and heat them in sequence to obtain iron tailings-based porous agglomerates. (2) The iron tailings-based porous aggregates obtained in step (1) are immersed in a functional compound liquid, ultrasonically treated, and then subjected to solid-liquid separation and drying treatment in sequence to obtain the iron tailings-based composite artificial soil.

5. The method for preparing iron tailings-based composite artificial soil according to claim 4, characterized in that, The mass ratio of iron tailings, plant fiber, foaming agent, additive and water in step (1) is 100:(0.5~10):(0.1~2):(5~20):(35~65); Preferably, the D50 of the iron tailings is ≤10μm; Preferably, the iron tailings, by mass percentage, comprise the following elements: O 58.8–59.1 wt%, Si 14.4–14.8 wt%, Al 12.2–12.9 wt%, K 5.48–5.6 wt%, Fe 4.1–4.2 wt%, Mg 0.6–0.7 wt%, Ba 2.68–2.75 wt%, Ni 0.45–0.5 wt%, and Ti 0.1–0.2 wt%. Preferably, the plant fiber includes any one or a combination of at least two of rice straw fiber, wheat straw fiber, straw fiber, coconut fiber, reed fiber, bamboo fiber, or cotton and linen fiber; Preferably, the plant fiber has a fiber length of 0.1 to 50 mm.

6. The preparation method according to claim 5, characterized in that, The foaming agent includes sodium ethoxylated alkyl sulfate and a nonionic surfactant; Preferably, the nonionic surfactant includes any one or a combination of at least two of coconut oil fatty acid diethanolamide, fatty alcohol polyoxyethylene ether, or fatty acid polyoxyethylene ester. Preferably, the content of sodium ethoxylated alkyl sulfate in the foaming agent is 50-80 wt%. Preferably, the content of nonionic surfactant in the foaming agent is 0-50 wt%. Preferably, the additives include clay and firing aids; Preferably, the sintering aid comprises a combination of at least two of sodium carbonate, calcium fluoride, or boron mud; Preferably, the clay content in the additive is 30-60 wt%. Preferably, the sodium carbonate content in the additive is 0-40 wt%. Preferably, the calcium fluoride content in the additive is 0-25 wt%. Preferably, the content of boron mud in the additive is 0-70 wt%.

7. The preparation method according to any one of claims 4-6, characterized in that, The stirring speed in step (1) is 500-1500 rpm; Preferably, the stirring time in step (1) is 2 to 30 minutes; Preferably, the molding process in step (1) includes droplet granulation or injection molding; Preferably, the drying temperature in step (1) is 50–120°C; Preferably, the drying process in step (1) takes 2 to 6 hours; Preferably, the temperature of the heat treatment in step (1) is 500–1000°C; Preferably, the heat treatment time in step (1) is 0.5 to 6 hours.

8. The preparation method according to any one of claims 4-7, characterized in that, The raw materials for preparing the functional compound solution in step (2) include: organic matter, fertilizer, trace element chelates and microbial derivatives; Preferably, the organic matter content in the functional compound solution is 50-70 wt%. Preferably, the organic matter includes any one or a combination of at least two of humic acid, biogas residue, or wood chips; Preferably, the fertilizer content in the functional compound solution is 20-40 wt%. Preferably, the fertilizer includes a slow-release nitrogen, phosphorus, and potassium compound fertilizer; Preferably, the content of trace elements in the functional compound solution is 5-10 wt%. Preferably, the trace elements include any one or a combination of at least two of iron, zinc, boron, copper, manganese, or selenium; Preferably, the content of microbial derivatives in the functional compound solution is 0.1-0.5 wt%. Preferably, the microbial derivative includes microbial strains or metabolites.

9. The preparation method according to any one of claims 4-8, characterized in that, The ultrasonic treatment time in step (2) is 2 to 20 minutes; Preferably, the power of the ultrasonic treatment in step (2) is 380-1200W; Preferably, the drying temperature in step (2) is 20–80°C; Preferably, the drying process in step (2) ends when the moisture content of the iron tailings-based composite artificial soil is ≤10wt%.

10. An application of the iron tailings-based composite artificial soil as described in any one of claims 1-3, characterized in that, The iron tailings-based composite artificial soil is used for soil restoration or planting greenery. Preferably, the soil to be restored includes any one of mine ecological restoration, saline-alkali land restoration, or compacted soil restoration.

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