A method for simultaneously activating nutrients and stabilizing heavy metals in coal gangue, and its product and application

Abstract

The present invention provides a method for simultaneously activating nutrients and stabilizing heavy metals in coal gangue, and its products and applications. Specifically, the method comprises: crushing the coal gangue, ball milling the coal gangue to a particle size of less than 50 mesh, and obtaining a specific surface area of ​​350-400m 2 / kg of preliminary activated coal gangue powder; mix it with an alkali activator and water in proportion and perform a hydrothermal reaction; centrifuge the reaction product, separate the solid and dry it to obtain activated coal gangue powder with activated nutrients and stabilized heavy metals. The scheme of the present invention uses a simple, efficient, low-energy, green and environmentally friendly method to simultaneously activate nutrients and stabilize heavy metals in coal gangue powder. The obtained activated coal gangue powder has a unique pore structure and a specific surface area of ​​500-600m 2 / kg, and the mineral phase composition changes significantly, the inert kaolinite is transformed into active chabazite and tobermorite, which makes it have good water absorption, water retention and ion exchange properties. In addition, the heavy metal cadmium, lead and arsenic in the activated coal gangue powder are transformed from active state to residual state.

Description

Technical Field

[0001] The invention belongs to the technical field of coal gangue resource utilization, and specifically relates to a method for simultaneously realizing nutrient activation and heavy metal stabilization in coal gangue, and a product and application thereof. Background Art

[0002] Gangue is a solid waste discharged during coal mining, washing, processing and utilization, accounting for 15%-20% of coal production. As the world's largest coal producer, my country produces a huge amount of gangue, which has become one of the largest industrial solid wastes in my country in terms of emission and accumulation. The accumulation of gangue will occupy a large amount of land and seriously pollute the environment. Although the comprehensive utilization rate of gangue has increased year by year in recent years, compared with the huge output and stock, my country's ability to handle gangue is still insufficient. Especially in the central and western regions where the output and storage of gangue are huge, the land is vast and sparsely populated, the economy is underdeveloped, the potential for local consumption is extremely small, and export is limited by transportation costs. Therefore, it is urgent to explore a universal, low-cost, high-consumption, and environmentally friendly gangue treatment and utilization model. Because gangue is similar to soil composition, it is compatible, cheap and easy to obtain. At the same time, studies have shown that when applied in appropriate amounts, gangue can improve soil structure, increase soil fertility, and promote soil microbial growth and metabolism. If coal gangue can be used to improve and repair a large amount of potential utilizable land resources in my country, it will effectively alleviate my country's land pressure and at the same time provide a low-cost and high-efficiency way out for the large amount of stockpiled coal gangue.

[0003] Gangue contains rich organic matter, silicon and trace elements required for plant growth. However, due to its stable chemical structure, high content of inert organic carbon, poor pore structure and multiple heavy metals, the land with gangue is faced with problems such as low activity of beneficial components, poor water and fertilizer retention, and high pollution risk. The stable macromolecular organic carbon in gangue is conducive to the formation of soil aggregates, but the organic matter in a stable state cannot be effectively utilized by microorganisms and plants. As an essential nutrient element for plants, silicon needs to be activated into effective silicon before it can be absorbed by plants, improve photosynthesis, increase nutrient utilization, and enhance plant tolerance to abiotic and biotic stresses, thereby improving the survival ability of plants in harsh environments. It can be seen that it is necessary to activate gangue, decompose the lattice structure, improve the activity of beneficial components, improve the physical and chemical properties of gangue, improve its water holding and fertilizer retention, and reduce its pollution and biological toxicity, so as to achieve the harmless and resource utilization of large amounts of accumulated gangue.

[0004] At present, the most studied methods for gangue activation are mechanical method, chemical method, microbial method and calcination method. Among them, mechanical method and chemical method are simple to operate and low in cost, but the effects of nutrient activation and heavy metal stabilization are limited; microbial method can increase the humus content and reduce the pollution of various heavy metals in gangue, but strain screening and synergistic compounding are difficult, the cycle is long and the operation is complicated; calcination method is efficient and simple, but high temperature consumes a lot of energy and organic carbon is oxidized, and organic matter is completely lost.

[0005] In summary, the biggest bottleneck currently facing the land application of coal gangue is to develop a coal gangue resource utilization technology that is simple to operate, green and low-carbon, fast and efficient, and can simultaneously achieve nutrient activation and heavy metal stabilization. Summary of the invention

[0006] The purpose of the present invention is to provide a method for simultaneously activating nutrients and stabilizing heavy metals in coal gangue, which can solve the problems of complicated and inefficient coal gangue activation methods in the prior art. Specifically, the technical solution provided by the present invention can solve the problems of low activity of beneficial components and high risk of heavy metal pollution in the resource utilization of original coal gangue through a one-step alkaline hydrothermal reaction, thereby preparing a highly active and pollution-free activated coal gangue powder, which has the advantages of simple operation, mild conditions, rapidity and high efficiency, and is particularly suitable for large-scale industrial production.

[0007] To achieve the above object, the present invention provides a method for simultaneously activating nutrients and stabilizing heavy metals in coal gangue, comprising the following steps:

[0008] (1) Mechanical and thermal chemical treatment of coal gangue: The coal gangue is crushed and ball-milled to a particle size below 50 mesh to obtain a specific surface area of ​​350-400m 2 / kg of preliminary activated coal gangue powder;

[0009] (2) Alkali activation of coal gangue powder: the obtained preliminary activated coal gangue powder, alkali activator and water are mixed evenly in a certain proportion, and a hydrothermal reaction is carried out at 120-200°C under stirring conditions;

[0010] (3) Solid-liquid separation: The products after the hydrothermal reaction are centrifuged and the solids are collected and dried to obtain activated coal gangue powder and an alkali activator solution in which nutrients are activated and heavy metals are stabilized.

[0011] In a preferred embodiment, in step (1), the main inorganic chemical composition of the coal gangue includes: SiO2 40-65%, Al2O3 16-36%, Fe2O3 2.28-14.63%, SO3 0.8-6.1%, CaO0.42-2.32%, MgO 0.18-2.41%, TiO2 0.90-4%, P2O5 0.07-0.24%, K2O+Na2O 1.45-3.9%, V2O5 0.08-0.13%, and the organic matter content in the coal gangue is 12-25%.

[0012] In a preferred embodiment, in step (1), during the ball milling treatment, the ball-to-material ratio is 10-15:1, the rotation speed is 200-300 rpm, and the ball milling time is 1-3 hours.

[0013] In a preferred embodiment, in step (2), the alkali activator includes one or more of wood ash, alkali residue, lime, light-burned magnesium oxide, sodium hydroxide, and potassium hydroxide.

[0014] In a preferred embodiment, in step (2), the mass ratio of the preliminarily activated gangue powder to the alkali activator is 1:(0.05-0.2); the solid-liquid mass ratio of the solid composed of the preliminarily activated gangue powder and the alkali activator to water is 1:(1-5).

[0015] In a preferred embodiment, in step (2), the hydrothermal reaction time is 2-8 hours, and the stirring speed of the hydrothermal reaction is 100-400 rpm.

[0016] In a preferred embodiment, in step (3), the recovered alkaline activator solution can be recycled for alkali activation of the gangue fraction in step (2).

[0017] In a preferred embodiment, in step (3), the drying method can be a conventional method known to those skilled in the art, such as drying at 60-80° C. for 2-4 hours.

[0018] Another object of the present invention is to provide activated coal gangue powder prepared by any of the above methods. Through the above green, environmentally friendly, low-energy consumption and high-efficiency preparation method, activated coal gangue powder with high activity and low heavy metal content can be obtained. The obtained product has excellent performance and broad application prospects.

[0019] In a preferred embodiment, the activated coal gangue powder mineral phase mainly includes chabazite and / or tobermorite, and its microscopic morphology is a hollow columnar porous structure with a specific surface area of ​​500-600m 2 / kg; the unique pore structure of the activated coal gangue powder can produce good water retention performance, and can be used as a fertilizer or soil conditioner.

[0020] In a preferred embodiment, the organic matter content of the activated coal gangue powder is above 13%, the effective silicon content is greater than 20%, the moisture content is less than 3%, the particle size passing through a 0.25 mm sieve accounts for more than 80%, and the powder is rich in nutrients such as silicon, phosphorus, potassium, calcium, and magnesium; wherein the organic matter is mainly humus, silicon and phosphorus are mainly soluble silicates and phosphates, potassium and magnesium are mainly soluble silicates and sulfates, and calcium is mainly slow-release silicates and sulfates, and the above nutrients are directly absorbed and utilized by plants and microorganisms.

[0021] In a preferred embodiment, the heavy metal cadmium, lead and arsenic in the activated coal gangue powder are converted from an active state to a residual state, and the total amount of various heavy metals meets the GB 38400-2019 "Limit Requirements for Toxic and Hazardous Substances in Fertilizers", which can effectively achieve harmlessness and has extremely low risks to the quality and safety of agricultural products, crop growth and soil ecological environment; in addition, the quality of the obtained product fully meets the NY / T 797-2004 "Silicon Fertilizer" standard.

[0022] Another object of the present invention is to provide activated coal gangue powder prepared by any of the above methods, which can be used in silicon-based fertilizers and / or soil conditioners.

[0023] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0024] 1. From the preparation method point of view: In the present invention, mechanical ball milling is first used to realize mechanical thermochemical reaction. This step not only greatly reduces the particle size of coal gangue, but also produces a large number of ·OH radicals and SO4·- radicals on the surface of coal gangue particles, which promotes the degradation of macromolecular organic matter in coal gangue into small molecular organic matter soluble in water such as humus and humic acid. Then, a one-step alkaline hydrothermal reaction method is used to accelerate the breaking of chemical bonds of macromolecular organic matter in coal gangue, the silicon oxygen tetrahedron and aluminum oxygen octahedron structure in aluminosilicate is destroyed, and effective nutrients are activated. As the alkaline hydrothermal reaction proceeds, a surface active material with a porous structure is reconstructed and generated, which has the effects of adsorption, exchange, precipitation and encapsulation on heavy metal ions, thereby passivating heavy metals. The overall method is simple and efficient, and has low requirements for equipment and energy consumption.

[0025] Moreover, after the mechanical thermochemical treatment process, the macromolecular organic matter is efficiently degraded, which makes the hydrothermal reaction conditions milder, and the amount of alkali activator is also very small, accounting for only 5-20% of the mass of the coal gangue to promote the efficient activation of silicon in the coal gangue. The relatively small amount of alkali activator used in the present invention can reduce the production cost on the one hand; on the other hand, it can make the loss of nitrogen, phosphorus and organic matter in the coal gangue extremely low (loss rate <20%), fully ensuring the basic requirement of using the activated coal gangue as fertilizer; in addition, based on the relatively low amount of alkali activator, the alkali activator can be recycled through step (3) to achieve the beneficial effect of no waste liquid discharge.

[0026] 2. From the perspective of the obtained product: the activated coal gangue powder prepared by the solution provided by the present invention has a fluffy and porous hollow columnar structure with a specific surface area of ​​500-600m 2 / kg, forming hydrophilic active groups on the surface, making it have strong adsorption, water absorption and chelation capabilities, which can enhance soil water holding capacity and improve soil physical and chemical properties. Analyzing its composition, the organic matter content in activated coal gangue powder is more than 13%, the effective silicon content is greater than 20%, the moisture content is less than 3%, and the proportion of particles passing through the 0.25mm sieve is more than 80%; the heavy metals cadmium, lead and arsenic in the coal gangue powder are transformed from active state to residual state, and the total amount of various heavy metals meets GB 38400-2019 "Limit Requirements for Toxic and Hazardous Substances in Fertilizers"; the product is rich in organic matter and a variety of trace elements, meeting the NY / T 797-2004 "Silicon Fertilizer" standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] These and / or other aspects and advantages of the present invention will become more clear and easier to understand from the following detailed description of the embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0028] Figure 1 X-ray powder diffraction phase analysis diagram of the original coal gangue raw material and the prepared activated coal gangue powder used in Example 1 of the present invention;

[0029] Figure 2 1 is a scanning electron microscope micrograph of the original coal gangue raw material and the prepared activated coal gangue powder used in Example 1 of the present invention, wherein the upper two figures are scanning electron microscope images of the original coal gangue, and the lower two figures are scanning electron microscope images of the activated coal gangue powder;

[0030] Figure 3 This is a graph showing the proportion of several heavy metal forms in the original gangue raw material and the prepared activated gangue powder used in Example 1 of the present invention. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods, but it should be understood that the protection scope of the present invention is not limited to the specific implementation methods.

[0032] The embodiments of the present invention provide a method for simultaneously activating nutrients and stabilizing heavy metals in coal gangue, and its products and applications, thereby solving the problem that the existing methods for activating coal gangue are complicated and cannot simultaneously activate nutrients and stabilize heavy metals in coal gangue. The activated coal gangue powder prepared by the method provided by the present invention has excellent fertility performance, is green and sustainable, and can effectively treat nutrient-poor soil, desertified soil and heavy metal-contaminated soil. The overall design concept of the present invention is in line with the national concept of waste-free city construction and sustainable development, and has broad application prospects.

[0033] The technical solution of the present application is described in detail below through specific embodiments:

[0034] Unless otherwise specified, the technical means used in the present invention are conventional means well known to those skilled in the art, and the various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods. The reagents used in the present invention are analytically pure unless otherwise specified. The coal gangue raw materials used in the present invention are collected from Ordos, Inner Mongolia, and their chemical composition is shown in Table 1, (%):

[0035] Table 1 Chemical composition of coal gangue raw materials (%)

[0036] <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> CaO MgO <![CDATA[Na2O]]> <![CDATA[K2O]]> <![CDATA[SO3]]> <![CDATA[TiO2]]> <![CDATA[MnO2]]> <![CDATA[P2O5]]> 48.60 19.65 4.94 1.86 0.23 0.067 1.40 3.19 1.22 0.063 0.158

[0037] Example 1

[0038] A method for simultaneously activating nutrients and stabilizing heavy metals in coal gangue comprises the following steps:

[0039] (1) Mechanical and thermochemical treatment of coal gangue: 100 kg of coal gangue was crushed and mechanically ball milled at a ball-to-material ratio of 10:1 and a rotation speed of 200 rpm for 1 hour until the coal gangue particle size was below 50 mesh and the specific surface area was 385 m 2 / kg of preliminary activated coal gangue powder;

[0040] (2) Alkali activation of coal gangue powder: In a wet heat reactor, 100 kg of the initially activated coal gangue powder, 10 kg of potassium hydroxide and 240 liters of water were stirred and mixed uniformly, and a hydrothermal reaction was carried out at 150° C. for 4 hours under a stirring condition of 100 rpm;

[0041] (3) Solid-liquid separation: The products after the hydrothermal reaction are separated by centrifugation to obtain 130 kg of activated coal gangue powder with activated nutrients and stabilized heavy metals and 220 liters of potassium hydroxide solution. The recovered potassium hydroxide solution can be recycled for the alkali activation process of the coal gangue powder. After drying, the activated coal gangue powder is dried to obtain 110 kg of activated coal gangue powder product.

[0042] The composition of the obtained activated coal gangue powder was tested, and the results showed that its organic matter content was 13.82%, the effective silicon content was 24.88%, the moisture content was 1.86%, and the particle size passing through the 0.25mm sieve accounted for 91.5%; the heavy metal cadmium, lead and arsenic in the coal gangue powder were converted from active state to residual state; the product quality met the NY / T797-2004 "Silicon Fertilizer" standard.

[0043] The specific test results are:

[0044] (I) The mineral phase composition of the original gangue raw material and the prepared activated gangue powder is as follows: Figure 1 As shown in the figure, it can be seen that the original coal gangue is mainly composed of quartz and kaolinite. The test shows that the effective silicon content (in terms of SiO2) in the original coal gangue is only 0.056%, the organic matter content is 13.92%, of which the easily oxidized organic matter content is 1.38% (accounting for 9.91%).

[0045] The mineral phase composition of the prepared activated coal gangue has undergone significant changes. The inert kaolinite has been transformed into active chabazite (hydrated silicate of sodium and calcium) and tobermorite (a hydrate of calcium silicate). The above components make the activated coal gangue have good water absorption, water retention and ion exchange properties. In addition, the organic matter content in the activated coal gangue powder is 13.82%, and the easily oxidized organic matter content is 8.38% (accounting for 60.64% of the total organic matter content). The main components of the organic matter are humus and humic acid. By effectively activating the inert organic matter, it can not only promote the formation of soil aggregates, but also provide direct absorption and utilization for plants and microorganisms. Furthermore, the active coal gangue powder has an effective silicon content (measured in SiO2) of 24.88%, a moisture content of 1.86%, and a fineness (passing a 250 μm standard sieve) of ≥90%, which meets the index requirements of NY / T 797-2004 "Silicon Fertilizer". It also contains rich trace elements required for plant growth. The specific trace element content is shown in Table 2.

[0046] Table 2 Trace element content in activated coal gangue powder (mg / kg)

[0047] Cu Fe Mn Zn B Mo Se 6.20 6238 56.65 25.38 19.96 1.99 2.87

[0048] (two) Figure 2The morphology of the original gangue raw material and the prepared activated gangue powder is shown. It can be seen from the figure that the particle size distribution of the activated gangue powder is more uniform, and the compact layered structure is transformed into a hollow columnar porous structure. The specific surface area data is 550m 2 / kg. It has strong ion exchange and adsorption properties, which can improve soil water retention, fertilizer retention and internal nutrient release functions.

[0049] (III) During the alkaline hydrothermal process, the main heavy metals in the activated coal gangue powder were transformed from the active state to the more stable residual state, achieving the simultaneous harmless treatment of multiple heavy metals in the coal gangue. The distribution of heavy metal forms in the original coal gangue raw materials and the prepared activated coal gangue powder is as follows: Figure 3 shown.

[0050] Example 2

[0051] A method for simultaneously activating nutrients and stabilizing heavy metals in coal gangue comprises the following steps:

[0052] (1) Mechanical and thermochemical treatment of coal gangue: 100 kg of coal gangue was crushed and mechanically ball milled at a ball-to-material ratio of 12:1 and a rotation speed of 240 rpm for 1.5 hours until the coal gangue particle size was below 60 mesh and the specific surface area was 400 m 2 / kg of preliminary activated coal gangue powder;

[0053] (2) Alkali activation of coal gangue powder: In a wet heat reactor, 100 kg of the initially activated coal gangue powder, 5 kg of sodium hydroxide, 5 kg of plant ash and 300 liters of water were stirred and mixed uniformly, and a hydrothermal reaction was carried out at 180° C. for 3 hours under a stirring condition of 260 rpm;

[0054] (3) Solid-liquid separation: The products after the hydrothermal reaction are separated by centrifugation to obtain 132 kg of activated coal gangue powder with activated nutrients and stabilized heavy metals and 278 liters of alkaline solution (a mixed solution of sodium hydroxide and wood ash). The recovered alkaline solution can be recycled for the alkali activation process of the coal gangue powder. After drying, the activated coal gangue powder is dried to obtain 112 kg of activated coal gangue powder product, which has an organic matter content of 15.2%, an effective silicon content of 23.8%, a moisture content of 2.5%, and a particle size of 88% passing through a 0.25 mm sieve. The heavy metals cadmium, lead and arsenic in the coal gangue powder are converted from an active state to a residual state. The product quality meets the NY / T 797-2004 "Silicon Fertilizer" standard.

[0055] Comparative Example 1

[0056] (1) Mechanical crushing of coal gangue: 100 kg of coal gangue is crushed and sieved to a particle size of less than 0.5-1.0 mm (about 16-30 mesh), and a specific surface area of ​​200-300 m2 / kg of coal gangue powder;

[0057] (2) Alkali activation of coal gangue powder: In a wet heat reactor, 100 kg of the initially activated coal gangue powder, 10 kg of potassium hydroxide and 240 liters of water were stirred and mixed uniformly, and a hydrothermal reaction was carried out at 150° C. for 4 hours under a stirring condition of 100 rpm;

[0058] (3) Solid-liquid separation: The products after the hydrothermal reaction are separated by centrifugation to obtain 130 kg of alkali-activated coal gangue powder and 220 liters of potassium hydroxide solution. The recovered potassium hydroxide solution can be recycled for the alkali activation process of the coal gangue powder. After drying, the activated coal gangue powder is dried to obtain 110 kg of alkali-activated coal gangue powder product.

[0059] The results of testing the composition of the obtained gangue product showed that its organic matter content was 14.2%, the effective silicon content was too low, only 10.5%, the moisture content was 2.7%, and the proportion of particles passing through the 0.25mm sieve was 72%; a small part of the heavy metals cadmium, lead and arsenic in the gangue powder was converted from active state to residual state, and most of them were still active; the product quality could not meet the NY / T797-2004 "Silicon Fertilizer" standard. In addition, the results of X-ray powder diffraction phase analysis showed that the phase spectrum of alkali-activated gangue powder was not significantly different from that of the original gangue, and the main components were still kaolinite and SiO2, and there was no obvious appearance of chabazite and tobermorite.

[0060] It can be seen from this that the technical solution of the present invention can simply, efficiently and with low energy consumption, simultaneously activate nutrients and stabilize heavy metals in coal gangue powder through mechanical thermochemical pretreatment and one-step alkaline hydrothermal reaction. The obtained activated coal gangue powder is rich in organic matter, silicon, phosphorus, potassium, calcium, magnesium and other nutrients, which are easily directly absorbed and utilized by plants and microorganisms. Among them, organic matter is mainly humus, silicon and phosphorus are mainly soluble silicates and phosphates, potassium and magnesium are mainly soluble silicates and sulfates, and calcium is mainly slow-release silicates and sulfates. The heavy metals cadmium, lead and arsenic in the coal gangue are all transformed from active states to residual states. Moreover, the activated coal gangue powder (activated coal gangue powder) has a unique pore structure with a specific surface area of ​​500-600m 2 / kg, has good water retention performance and can be used as silicon-based fertilizer or soil conditioner.

[0061] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A method for simultaneously activating nutrients and stabilizing heavy metals in coal gangue, characterized in that: The following steps are involved: (1) Mechanical and thermal chemical treatment of coal gangue: The coal gangue is crushed and ball-milled to a particle size below 50 mesh to obtain a specific surface area of ​​350-400m 2 / kg of preliminary activated coal gangue powder; (2) Alkali activation of coal gangue powder: the initially activated coal gangue powder, alkali activator and water are mixed evenly in a certain proportion, and a hydrothermal reaction is carried out at 120-200°C under stirring conditions; (3) Solid-liquid separation: The products after the hydrothermal reaction are centrifuged and the solids are collected and dried to obtain activated coal gangue powder and alkaline activator solution in which nutrients are activated and heavy metals are stabilized; Wherein, in step (1), the main inorganic chemical composition of the coal gangue includes: SiO2 40-65%, Al2O3 16-36%, Fe2O3 2.28-14.63%, SO3 0.8-6.1%, CaO 0.42-2.32%, MgO 0.18-2.41%, TiO2 0.90-4%, P2O5 0.07-0.24%, K2O+Na2O 1.45-3.9%, V2O5 0.08-0.13%, and the organic matter content in the coal gangue is 12-25%; In step (2), the mass ratio of the initially activated coal gangue powder to the alkali activator is 1:(0.05-0.2); The activated coal gangue powder prepared in step (3) mainly comprises chabazite and / or tobermorite, and its microscopic morphology is a hollow columnar porous structure with a specific surface area of ​​500-600m 2 / kg; the organic matter content of the activated coal gangue powder is above 13%, the effective silicon content is greater than 20%, the moisture content is less than 3%, and the proportion of particles with a diameter passing through a 0.25mm sieve is more than 80%; the heavy metal cadmium, lead and arsenic in the coal gangue powder are all converted from an active state to a residual state; the product quality meets the NY / T 797-2004 "Silicon Fertilizer" standard.

2. The method for simultaneously activating nutrients and stabilizing heavy metals in coal gangue as claimed in claim 1, characterized in that: In step (2), the alkali activator includes one or more of wood ash, alkali residue, lime, light-burned magnesium oxide, sodium hydroxide, and potassium hydroxide.

3. The method for simultaneously activating nutrients and stabilizing heavy metals in coal gangue as claimed in claim 1, characterized in that: In step (2), the solid-to-liquid ratio of the solid composed of the initially activated coal gangue powder and the alkali activator to water is 1:(1-5).

4. The method for simultaneously activating nutrients and stabilizing heavy metals in coal gangue as claimed in claim 1, characterized in that: In step (2), the hydrothermal reaction time is 2-8 hours, and the stirring speed of the hydrothermal reaction is 100-400 rpm.

5. The method for simultaneously activating nutrients and stabilizing heavy metals in coal gangue as claimed in claim 1, characterized in that: In step (3), the recovered alkali activator solution can be recycled for alkali activation of coal gangue powder in step (2).

6. The activated coal gangue powder prepared by the method according to any one of claims 1 to 5.

7. The activated coal gangue powder prepared as claimed in claim 6 is used in silicon-based fertilizers and / or soil conditioners.

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