High-water-binding-capacity graphite tailing soil composite modifier and preparation method thereof

Abstract

The invention belongs to the technical field of ecological restoration, and particularly relates to a high-water-binding-capacity graphite tailing soil composite modifier and a preparation method thereof. The high-water-holding-capacity graphite tailing soil composite modifier comprises the following raw materials in parts by weight: 0.5-2 parts of fly ash, 5.5-7 parts of bentonite, 5.5-7 parts of cow dung and 6-8 parts of biochar, the components of the high-water-holding-capacity graphite tailing soil composite modifier are reasonable, and the bentonite not only can improve the water-holding capacity of graphite tailing soil, but also can enhance the plasticity of the graphite tailing soil; the biochar can improve the porosity of the tailings and reduce the volume weight of the tailings; organic matters in the cow dung not only can be used as an adhesive for bonding soil particles, but also can promote the formation of soil aggregates. The composite modifier disclosed by the invention has the properties of high water binding capacity, high plasticity and high organic matter content, and has a good effect of improving the soil structure, effectively improving the soil fertility effect and enhancing the soil ecological function effect.

Description

Technical Field

[0001] This invention belongs to the field of ecological restoration technology, specifically relating to a high water-holding capacity graphite tailings soil composite conditioner and its preparation method. Background Technology

[0002] Graphite is one of my country's important strategic mineral resources, with wide-ranging applications, especially in energy, electronics, metallurgy, and machinery. As a superior material with excellent electrical conductivity, high-temperature resistance, and lubrication properties, graphite has played a crucial role in promoting my country's economic development and technological progress, particularly in high-tech industries such as new materials, lithium batteries, and nuclear energy. In 2023, global graphite production reached 1.6 million tons, with China producing 1.23 million tons, making it the world's largest graphite reserve holder. However, my country's graphite resources mainly come from the mining and processing of primary ore, which generates a large amount of graphite tailings waste. The accumulation of graphite tailings occupies significant land resources. my country's mining industry started relatively late, and the development of mineral processing technology is uneven across the country, resulting in a large amount of valuable key minerals remaining in the tailings. If discharged indiscriminately, this will cause a serious waste of resources. On the other hand, the reagents added during the ore beneficiation process will remain in the tailings, resulting in the tailings containing heavy metal ions, and even pollutants such as arsenic and mercury. If not properly disposed of, they will flow into rivers or seep into the ground with the tailings water, polluting rivers and groundwater sources.

[0003] In the field of graphite tailings ecological restoration, improving tailings into soil is a core step, and the selection and application of amendments directly determine the restoration effect. Traditional graphite tailings amendments often use single-material organic fertilizers or mineral materials, which have the drawbacks of limited functionality and limited improvement effect. Although single organic fertilizers can supplement organic matter, they have a weak effect on improving the pore structure of tailings; although single mineral materials can regulate soil physical properties, they lack nutrient supply capacity and are difficult to achieve a synergistic improvement in the water retention, structure, and fertility of tailings.

[0004] In view of this, the inventors aim to design a high water-holding capacity graphite tailings soil composite conditioner. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned problems existing in the traditional technology and to provide a high water-holding capacity graphite tailings soil composite amendment and its preparation method.

[0006] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0007] This invention provides a high water-holding capacity graphite tailings soil composite conditioner, comprising the following raw materials in parts by weight:

[0008] 0.5 to 2 parts fly ash

[0009] 5.5–7 parts bentonite

[0010] 5.5 to 7 parts cow dung

[0011] 6-8 parts of biochar.

[0012] Furthermore, in the above-mentioned high water-holding capacity graphite tailings soil composite conditioner, the particle size of the fly ash is 400-600 mesh, and the fly ash is at least one of anthracite, F-type fly ash collected from the combustion of bituminous coal, and low-calcium fly ash.

[0013] Furthermore, in the above-mentioned high water-holding capacity graphite tailings soil composite amendment, the bentonite has a particle size >200 mesh, and the bentonite is a yellow-green calcium-based bentonite.

[0014] Furthermore, in the aforementioned high water-holding capacity graphite tailings soil composite conditioner, the cow manure has a particle size >18 mesh, and the cow manure used is fresh cow manure from a livestock farm. Using fresh cow manure from a livestock farm ensures that the cow manure is not contaminated by harmful pollutants such as heavy metals and pathogens, and is rich in natural organic matter and nutrients such as nitrogen, phosphorus, and potassium.

[0015] Furthermore, in the above-mentioned high water-holding graphite tailings soil composite amendment, the method for treating the cow manure is as follows: using fresh cow manure from a farm as the initial raw material, placing the collected cow manure in a drying oven, drying it at 60°C for 26-48 hours, air-drying it, then crushing it in a pulverizer, and finally screening it in a vibrating screen to obtain cow manure within the required particle size range.

[0016] Furthermore, in the above-mentioned high water-holding capacity graphite tailings soil composite amendment, the cow manure is turned over every 2 hours during the air-drying process to ensure uniform evaporation of moisture and avoid localized mold growth. After 24 hours of air-drying, the cow manure sample is taken out, cooled to room temperature, and weighed. It is weighed again every 2 hours. If there is no significant difference between the two weighings, the cow manure air-drying is considered complete.

[0017] Furthermore, in the above-mentioned high water-holding graphite tailings soil composite conditioner, the biochar has a particle size of <2mm, and the biochar is corn stalk biochar with a loose and porous structure.

[0018] Furthermore, in the above-mentioned high water-holding capacity graphite tailings soil composite amendment, the preparation method of the biochar is as follows: corn stalks are placed in a drying oven and completely dried at 105°C; the dried corn stalks are put into a pulverizer and pulverized to a particle size ≤2mm; the pulverized corn stalks are placed in an electric furnace and kept at 500-600°C for 2-3 hours for high-temperature pyrolysis and carbonization; after the temperature inside the furnace naturally cools to room temperature, the carbonized product is taken out; it is pulverized again and passed through a 2mm sieve to obtain corn stalk biochar.

[0019] This invention also provides a method for preparing a high water-holding capacity graphite tailings soil composite conditioner, comprising the following steps:

[0020] S1. Accurately weigh each pretreated raw material according to the weight ratio;

[0021] S2. Place the weighed fly ash, bentonite, cow dung and biochar into a ribbon mixer and stir at a speed of 300-500 r / min for 15-20 min.

[0022] The beneficial effects of this invention are:

[0023] 1. This invention uses fly ash as a raw material, which improves the pore structure of tailings, enhances the bonding performance between raw materials, and strengthens soil structural stability.

[0024] 2. This invention uses bentonite as a raw material to improve the water retention and moisture regulation capacity of tailings soil, prevent tailings particles from dispersing, and enhance the plasticity and buffering capacity of tailings soil.

[0025] 3. This invention uses cow dung as raw material to improve the problem of insufficient organic matter in tailings soil, enhance the fertility and aggregate stability of tailings soil, transform the soil towards a suitable environment, and comprehensively utilize rural solid waste resources.

[0026] 4. This invention uses biochar as raw material to improve the pore structure, promote microbial activity, achieve comprehensive improvement of tailings soil, save improvement costs and resource consumption, and also realize the high-value utilization of agricultural waste.

[0027] 5. The high water-holding capacity graphite tailings soil composite conditioner of the present invention has a reasonable composition. The composite conditioner has the properties of high water-holding capacity, high plasticity and high organic matter content. It has a good effect on improving soil structure, effectively improving soil fertility and enhancing soil ecological function. It has strong applicability and scalability, green and environmentally friendly raw materials, and good long-term effect and economy.

[0028] Of course, any product implementing this invention does not necessarily need to achieve all of the above advantages at the same time. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] This invention provides a composite soil conditioner that can improve the water-holding capacity, plasticity, and organic matter content of graphite tailings soil. Bentonite, as a natural clay mineral, exhibits significant advantages in sandy soil improvement due to its unique adsorption, ion exchange, and moisture regulation capabilities. Furthermore, the resource utilization of agricultural waste (corn stalks), rural solid waste (cow dung), and industrial byproduct (fly ash) is an important direction for sustainable development. Converting these wastes into raw materials for tailings conditioner not only reduces improvement costs but also achieves the ecological benefits of "treating waste with waste," aligning with the concept of circular economy development. An ideal composite soil conditioner should possess multiple functions, including enhancing tailings water-holding capacity, improving pore structure, and supplementing nutrients. Through the complementary advantages of different components, it achieves comprehensive improvement of the physicochemical properties of graphite tailings soil, creating a suitable substrate environment for plant growth and promoting the reconstruction and restoration of the ecosystem in graphite tailings areas.

[0031] The specific embodiments of the present invention are as follows:

[0032] Example 1

[0033] This embodiment provides a high water-holding capacity graphite tailings soil composite conditioner, which is composed of the following raw materials in parts by weight:

[0034] 1 part fly ash, 6 parts bentonite, 6 parts cow dung, and 7.5 parts biochar.

[0035] The preparation method of cow dung is as follows: Fresh cow dung is used as the initial raw material. The collected cow dung is placed in a DHG-9070A tabletop blower drying oven at 60℃ for 36 hours to ensure complete air drying. After drying, it is placed in an FW-177 Chinese herbal medicine pulverizer for crushing, and then placed in an XSB-88 vibrating screen to screen and obtain cow dung within the required particle size range.

[0036] The preparation method of biochar is as follows: corn stalks are placed in a DHG-9070A tabletop drying oven at 105℃ for 48 hours to ensure complete drying, and then crushed into particles with a particle size of ≤2mm using an FW-177 plant pulverizer; the crushed corn stalks are placed in an SXL-1008 programmable box-type electric furnace at 550℃ for 2.5 hours for high-temperature pyrolysis carbonization, and after the temperature inside the furnace has naturally cooled to room temperature, the carbonized product is taken out, crushed again and passed through a 2mm sieve to obtain corn stalk biochar.

[0037] The preparation method of this composite modifier is as follows: accurately weigh each pretreated raw material according to the weight ratio; place the weighed fly ash, bentonite, cow dung and biochar in a ribbon mixer and stir at a speed of 400 r / min for 18 min.

[0038] The following data were obtained from testing: the effect of the composite modifier on the composition of water-stable agglomerates in the tailings was analyzed, and the bulk density of the tailings was 1.26 g / cm³. 3The total porosity was 45.63%, the mass of tailings agglomerates >0.25mm was 64.06%, the saturated water holding capacity was 358.33g / kg, and the field water holding capacity was 160.77g / kg.

[0039] Example 2

[0040] This embodiment provides a high water-holding capacity graphite tailings soil composite conditioner, which is composed of the following raw materials in parts by weight:

[0041] 1.5 parts fly ash, 5.5 parts bentonite, 6.5 parts cow dung, and 7 parts biochar.

[0042] The preparation method of cow dung is as follows: Fresh cow dung is used as the initial raw material. The collected cow dung is placed in a DHG-9070A tabletop blower drying oven at 60℃ for 36 hours to ensure complete air drying. After drying, it is placed in an FW-177 Chinese herbal medicine pulverizer for crushing, and then placed in an XSB-88 vibrating screen to screen and obtain cow dung within the required particle size range.

[0043] The preparation method of biochar is as follows: corn stalks are placed in a DHG-9070A tabletop drying oven at 105℃ for 48 hours to ensure complete drying, and then crushed into particles with a particle size of ≤2mm using an FW-177 plant pulverizer; the crushed corn stalks are placed in an SXL-1008 programmable box-type electric furnace at 550℃ for 2.5 hours for high-temperature pyrolysis carbonization, and after the temperature inside the furnace has naturally cooled to room temperature, the carbonized product is taken out, crushed again and passed through a 2mm sieve to obtain corn stalk biochar.

[0044] The preparation method of this composite modifier is as follows: accurately weigh each pretreated raw material according to the weight ratio, place the weighed fly ash, bentonite, cow dung and biochar in a ribbon mixer and stir at a speed of 400 r / min for 18 min.

[0045] The following data were obtained from testing: the effect of the composite modifier on the composition of water-stable agglomerates in the tailings was measured, with a tailings bulk density of 1.31 g / cm³. 3 The total porosity was 44.87%, the mass of tailings agglomerates >0.25mm was 59.66%, the saturated water holding capacity was 353.27g / kg, and the field water holding capacity was 157.84g / kg.

[0046] Comparative Example 1

[0047] The difference between this comparative example and Example 1 is that the high water-holding graphite tailings soil composite conditioner does not contain fly ash, while the composition of other raw materials and preparation methods remain unchanged.

[0048] The following data were obtained from testing: the effect of the composite modifier on the composition of water-stable agglomerates in the tailings was measured, with a tailings bulk density of 1.39 g / cm³. 3The total porosity was 43.15%, the mass of tailings agglomerates >0.25mm was 41.64%, the saturated water holding capacity was 342.23g / kg, and the field water holding capacity was 150.84g / kg.

[0049] Comparative Example 2

[0050] The difference between this comparative example and Example 1 is that the high water-holding graphite tailings soil composite conditioner does not contain bentonite, while the composition of other raw materials and preparation methods remain unchanged.

[0051] The following data were obtained from testing: the effect of the composite modifier on the composition of water-stable agglomerates in the tailings, with a tailings bulk density of 1.36 g / cm³. 3 The total porosity was 45.02%, the mass of tailings agglomerates >0.25mm was 43.72%, the saturated water holding capacity was 346.96g / kg, and the field water holding capacity was 154.62g / kg.

[0052] Comparative Example 3

[0053] The difference between this comparative example and Example 1 is that the high water-holding graphite tailings soil composite conditioner does not contain cow dung, while the composition of other raw materials and preparation methods remain unchanged.

[0054] The following data were obtained from testing: the effect of the composite modifier on the composition of water-stable agglomerates in the tailings, with a tailings bulk density of 1.37 g / cm³. 3 The total porosity is 46.95%, the mass of tailings agglomerates >0.25mm is 38.34%, the saturated water holding capacity is 338.42g / kg, and the field water holding capacity is 149.97g / kg.

[0055] Comparative Example 4

[0056] The difference between this comparative example and Example 1 is that the high water-holding graphite tailings soil composite conditioner does not contain biochar, while the composition of other raw materials and preparation methods remain unchanged.

[0057] The following data were obtained from testing: the effect of the composite modifier on the composition of water-stable agglomerates in the tailings, with a tailings bulk density of 1.42 g / cm³. 3 The total porosity was 41.63%, the mass of tailings agglomerates >0.25mm was 40.35%, the saturated water holding capacity was 336.46g / kg, and the field water holding capacity was 145.76g / kg.

[0058] The test results show that both the examples and the comparative examples meet the basic performance requirements of the composite modifier.

[0059] A comparison of Example 1 with Comparative Examples 1-4 shows that the high water-holding capacity graphite tailings soil composite conditioner has better overall performance. Therefore, the high water-holding capacity graphite tailings soil composite conditioner of this invention has a reasonable composition. The bentonite in the graphite tailings soil composite conditioner of this invention not only improves the water retention of graphite tailings soil but also enhances its plasticity. The biochar in the graphite tailings soil composite conditioner of this invention can improve the porosity of tailings and reduce their bulk density. The cow dung in the graphite tailings soil composite conditioner of this invention, with its organic matter, can not only act as a binder for soil particles but also promote the formation of soil aggregates.

[0060] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high water-holding capacity graphite tailings soil composite conditioner, characterized in that, Including the following parts by weight of raw materials: 0.5 to 2 parts fly ash 5.5–7 parts bentonite 5.5 to 7 parts cow dung 6-8 parts of biochar.

2. The high water-holding capacity graphite tailings soil composite conditioner according to claim 1, characterized in that, The fly ash has a particle size of 400-600 mesh, and the fly ash is at least one of anthracite, F-type fly ash collected from the combustion of bituminous coal, and low-calcium fly ash.

3. The high water-holding capacity graphite tailings soil composite conditioner according to claim 1, characterized in that, The bentonite has a particle size >200 mesh, and the bentonite is a yellow-green calcium-based bentonite.

4. The high water-holding capacity graphite tailings soil composite conditioner according to claim 1, characterized in that, The cow manure has a particle size >18 mesh and is made from fresh cow manure from a farm.

5. The high water-holding capacity graphite tailings soil composite conditioner according to claim 4, characterized in that, The method for processing cow manure is as follows: Fresh cow manure from the farm is used as the initial raw material. The collected cow manure is placed in a drying box and dried at 60°C for 26-48 hours. After air drying, it is crushed in a pulverizer and then screened in a vibrating screen to obtain cow manure within the required particle size range.

6. The high water-holding capacity graphite tailings soil composite conditioner according to claim 5, characterized in that, During the air-drying process, the cow dung should be turned over every 2 hours to ensure even evaporation of moisture and avoid localized mold growth. After 24 hours of air-drying, the cow dung sample should be taken out, cooled to room temperature, and weighed. It should be weighed again every 2 hours. If there is no significant difference in weight between the two weighings, the cow dung air-drying process is considered complete.

7. The high water-holding capacity graphite tailings soil composite conditioner according to claim 1, characterized in that, The biochar has a particle size of <2mm and is corn stalk biochar with a loose and porous structure.

8. The high water-holding capacity graphite tailings soil composite conditioner according to claim 7, characterized in that, The preparation method of the biochar is as follows: corn stalks are placed in a drying oven and completely dried at 105℃; the dried corn stalks are put into a pulverizer and pulverized to a particle size ≤2mm; the pulverized corn stalks are placed in an electric furnace and kept at 500~600℃ for 2~3h for high-temperature pyrolysis carbonization; after the temperature inside the furnace naturally cools to room temperature, the carbonized product is taken out; it is pulverized again and passed through a 2mm sieve to obtain corn stalk biochar.

9. The high water-holding capacity graphite tailings soil composite conditioner according to any one of claims 1 to 8, characterized in that, Its preparation method includes the following steps: S1. Accurately weigh each pretreated raw material according to the weight ratio; S2. Place the weighed fly ash, bentonite, cow dung and biochar into a ribbon mixer and stir at a speed of 300-500 r / min for 15-20 min.