Multi-granularity iron tailings composite organic matrix, and preparation method and application thereof

Abstract

The application discloses a kind of multi-particle grade iron tailings composite organic matrix and its preparation method and application, belong to the technical field of composite organic matrix, the application uses multi-particle grade tailings (fine tailings, total tailings and fine tailings) Collaborative compound agricultural organic matter, by the gradation optimization of coarse and fine particles, build stable, continuous pore structure, realize the collaborative improvement of aeration and water retention capacity;At the same time, using the adsorption and buffering effect of organic matter, effectively dilute the soluble salt concentration in the matrix, reduce the risk of salt stress, create a suitable environment for plant growth. With the increase of total tailings / fine tailings ratio, the matrix conductivity decreases, the bulk density increases, the aeration porosity improves, and the water holding porosity remains relatively stable, indicating that the ratio of multi-particle grade tailings can improve the physical and chemical properties of the matrix.

Description

Technical Field

[0001] This invention belongs to the technical field of composite organic matrix, specifically relating to a multi-granular iron tailings composite organic matrix, its preparation method, and its application. Background Technology

[0002] With the continuous development of mineral resources and the mineral processing industry, my country's mine solid waste emissions have remained at a high level for a long time. Among them, the large stockpile of tailings and the long storage period have become the core bottleneck restricting the ecological sustainable development of mining areas. The long-term open-air storage of large amounts of tailings not only occupies a lot of land resources, but is also susceptible to wind erosion, water erosion and rainwater leaching, releasing soluble salts and heavy metal ions, which pose a serious ecological risk to the surrounding soil, water bodies and ecosystems.

[0003] In terms of resource utilization, tailings are traditionally used mainly in building materials such as concrete aggregates and roadbed fillers. However, due to insufficient performance stability and high processing costs, the overall resource conversion rate is low, making it difficult to fundamentally eliminate solid waste inventory. Meanwhile, traditional ecological restoration substrates for mining areas rely heavily on natural soil and river sand. Large-scale mining not only causes secondary consumption of land and mineral resources but also fails to adapt to the special site conditions of mining areas, such as barrenness, drought, and salinization, resulting in high restoration costs, difficulty in vegetation establishment, and low survival rates. How to achieve high-value green utilization of mining solid waste and develop new ecological restoration substrates suitable for the harsh environment of mining areas, thus achieving a win-win situation for both "solid waste resource utilization" and "mining area ecological restoration," has become a key technical challenge that the industry urgently needs to solve.

[0004] Existing research confirms that tailings have a sand-like structure and are rich in essential plant minerals such as Si, Ca, and Mg, thus possessing the basic conditions to serve as a raw material for ecological restoration substrates. However, the application of single-size tailings has significant drawbacks: fine-grained tailings, due to their small particle size and large specific surface area, easily lead to substrate compaction and insufficient aeration pores, severely restricting plant root respiration and growth; while total tailings dredged sand and fine tailings dredged sand have good aeration, their water retention is weak when used alone, and the soluble salts accumulated in tailings can easily cause salt stress on plant germination, resulting in low germination rates and difficulty in seedling survival. Therefore, single-size tailings substrates cannot simultaneously achieve both aeration and water retention, and have a high risk of salt damage, failing to meet the basic requirements for vegetation establishment in mining area ecological restoration.

[0005] In contrast, the technical approach of synergistically compounding agricultural organic matter with multi-stage tailings (fine-grained tailings, total tailings dredged sand, and fine tailings dredged sand) is expected to construct a stable and continuous pore structure through optimized particle size distribution, thereby achieving a synergistic improvement in aeration and water retention. Simultaneously, the adsorption and buffering effects of organic matter can effectively dilute the concentration of soluble salts in the substrate, reducing the risk of salt stress and creating a suitable environment for plant growth. However, current research on the synergistic effects of the microstructure of multi-stage tailings, the salt regulation mechanism, and its impact on the key germination stages of pioneer plants such as ryegrass is still in its infancy, lacking systematic scientific evidence and technical support.

[0006] Based on this, the present invention is proposed. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a multi-granular iron tailings composite organic matrix and its preparation method and application to solve the problems mentioned in the background art or achieve better technical effects.

[0008] In order to solve the above-mentioned technical problems, the inventors derived the technical solution of the present invention through practice and summarization. The present invention discloses a multi-grained iron tailings composite organic matrix, the components of which are as follows by weight: 28-69 parts of total tailings sand, 15-53 parts of fine tailings and 15-22 parts of agricultural organic matter.

[0009] Or 27-68 parts fine tailings sand, 16-51 parts fine tailings and 16-22 parts agricultural organic matter;

[0010] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer; wherein, the mass percentage of coconut coir is 20%; the mass percentage of pine bark is 20%; the mass percentage of perlite is 20%; the mass percentage of black soil is 20%; and the mass percentage of organic fertilizer is 20%.

[0011] Further, by weight, the components are as follows: 58 parts total tailings sand, 20 parts fine tailings and 22 parts agricultural organic matter;

[0012] Or 49 parts fine tailings sand, 33 parts fine tailings and 18 parts agricultural organic matter.

[0013] Furthermore, the total tailings dredged sand, by mass percentage, comprises 54.65% SiO2, 19.18% Al2O3, and 7.13% Na2O; the particle size of the total tailings dredged sand is ≤4mm.

[0014] Furthermore, the fine tailings sand, by mass percentage, comprises 57.43% SiO2, 19.43% Al2O3, and 6.55% Na2O; the particle size of the fine tailings sand is ≤4mm.

[0015] Furthermore, the fine-grained tailings, by mass percentage, comprise 53.86% SiO2, 18.55% Al2O3, and 9.97% Fe2O3; the particle size of the fine-grained tailings is -200 mesh.

[0016] Furthermore, the preparation method of any of the above-mentioned multi-size iron tailings composite organic matrix comprises the following steps:

[0017] S1: Using total tailings / fine tailings and fine-grained tailings as inorganic raw materials, the materials are treated by impurity removal and drying to remove impurities and control the moisture content of the inorganic raw materials.

[0018] S2: Pre-treat the agricultural organic fertilizer, then add it to the mixing equipment according to the ratio and stir evenly to adjust the moisture content of the agricultural organic fertilizer;

[0019] S3: Premix the inorganic raw materials obtained from S1 for 5-10 minutes, then add the agricultural organic fertilizer obtained from S2 pretreatment, and continue stirring for 10-15 minutes. There is no extrusion or high-temperature treatment throughout the process, and the natural porous structure is preserved to finally obtain a multi-particle-size iron tailings composite matrix.

[0020] Furthermore, in S1, the moisture content is controlled as follows: the total tailings moisture content is 8.21%, the fine tailings moisture content is 14.03%, and the fine-grained tailings moisture content is 32%.

[0021] Furthermore, in S2, the pretreatment includes: crushing coconut coir, perlite and black soil and adjusting the moisture content to 50-60%; crushing pine bark to 3-5mm; sieving organic fertilizer to remove impurities; and adjusting the moisture content of agricultural organic fertilizer to 55%.

[0022] Furthermore, the application of any of the above-described multi-grain size iron tailings composite organic substrates in the cultivation of ryegrass plants.

[0023] Furthermore, the cultivation method for the aforementioned application is as follows:

[0024] Fill 2.5L / pot flowerpots with the composite substrate, level it without squeezing, and sow 100 perennial ryegrass seeds in each pot; place the flowerpots on a cultivation rack and cultivate them, controlling the light intensity to 2.0 × 10⁻⁶. 4 Lux, light duration 8h / d (8:00~16:00); water 20mL twice a day, morning and evening, no additional fertilizer applied, cultivation period 20 days.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] (1) This invention uses multi-grade tailings (fine tailings, total tailings sand and fine tailings sand) to synergistically compound agricultural organic matter. Through the optimization of the gradation of coarse and fine particles, a stable and continuous pore structure is constructed to achieve synergistic improvement of aeration and water retention. At the same time, the adsorption and buffering effect of organic matter is used to effectively dilute the concentration of soluble salts in the matrix, reduce the risk of salt stress, and create a suitable environment for plant growth.

[0027] (2) This invention provides an ecological restoration matrix formulation based on multi-grade tailings synergistic compounding, which optimizes the pore structure by using coarse and fine particle gradation and regulates the salt content by improving organic matter, thereby comprehensively improving the physical properties and environmental safety of the matrix.

[0028] (3) As the proportion of total tailings / fine tailings increases, the matrix conductivity decreases, the bulk density increases, the aeration porosity increases, and the water-holding porosity remains relatively stable, indicating that the proportion control of multi-size tailings can improve the physical and chemical properties of the matrix.

[0029] (4) This invention clarifies the molecular / physical mechanism of the synergistic effect of multi-stage tailings on the regulation of matrix pore structure and salinity, and screens out the optimal formula for the germination of ryegrass and the establishment of vegetation in mining areas, providing an efficient and low-cost technical solution for the large-scale resource utilization of mine solid waste and the ecological restoration of mining areas. Detailed Implementation

[0030] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to specific examples.

[0031] Unless otherwise specified, all raw materials or reagents used in the following examples are commercially available products.

[0032] The main components of the total tailings dredged sand are SiO2 (54.65%), Al2O3 (19.18%) and Na2O (7.13%); the particle size of the total tailings dredged sand is ≤4mm.

[0033] The main components of fine-tailed sand are SiO2 (57.43%), Al2O3 (19.43%) and Na2O (6.55%); the particle size of fine-tailed sand is ≤4mm.

[0034] The main components of the fine-grained tailings are SiO2 (53.86%), Al2O3 (18.55%), and Fe2O3 (9.97%); the particle size of the fine-grained tailings is -200 mesh.

[0035] Agricultural organic matter:

[0036] Coconut coir: Particle size range of 2~8mm, large pieces of coconut husk fiber larger than 10mm are removed to ensure matrix uniformity; EC value (electrical conductivity) ≤1.2 mS / cm (to prevent salt damage); pH value range of 5.0~6.5 (suitable for acidic environments); water holding capacity ≥8 times its own dry weight; fiber length 1~5cm, with good toughness to prevent matrix compaction caused by excessive grinding.

[0037] Pine bark: Particle size range 5~20mm (medium to coarse), serving as a "skeleton" support material for the matrix. pH value 4.5~6.0; bulk density 0.2~0.4g / cm³ 3 It has excellent breathability.

[0038] Perlite: with a particle size range of 1~5mm, it complements the particle size distribution of tailings and improves porosity.

[0039] Black soil: ≤10% of the soil particles are silt with a particle size of less than 0.25mm to prevent compaction; free of large particles such as stones and plastics.

[0040] Neutral organic fertilizer: Neutral organic fertilizer includes three categories: well-rotted livestock and poultry manure, leaf mold organic fertilizer, and straw well-rotted organic fertilizer. Well-rotted livestock and poultry manure uses sheep manure, chicken manure, and cow manure as raw materials. The manure is mixed with straw / soil in a 1:1 ratio, the moisture content is adjusted to 50%~60%, the pile is piled up to a height of 1.2~1.5 meters, and aerobic fermentation is carried out at 55~65℃ for 15~20 days. During this period, the pile is turned every 3~5 days until there is no odor, it turns dark brown, and the pH is stable at 6.5~7.5.

[0041] Leaf mold organic fertilizer is made from broad-leaved tree fallen leaves. After being crushed, the leaves are mixed with garden soil and straw in a ratio of 3:2:1. EM bacteria are added and the mixture is piled up for fermentation for 2-3 months, during which time the pile is turned over 2-3 times. After the composting is complete, impurities are removed to obtain neutral leaf mold fertilizer.

[0042] Straw composted organic fertilizer is made from corn, wheat, and rice straw. The straw is crushed to 2-3 cm and mixed with livestock and poultry manure and oilseed cake in a ratio of 4:1:0.5. After adding composting agents, the compost is fermented for 20-30 days at a controlled temperature of 55-65℃. After fermentation, the compost is sieved to obtain neutral straw organic fertilizer.

[0043] Neutral organic fertilizer is produced through aerobic fermentation throughout the entire process. By controlling the carbon-nitrogen ratio, moisture, and temperature, the pH of the product is kept stable at 6.5-7.5. It has balanced nutrients and a wide range of applications. Compared with acidic organic fertilizers prepared through anaerobic fermentation or by adding organic acids, which have a pH of 4.5-5.5, it is more suitable for improving most neutral to slightly acidic soils and for crop cultivation.

[0044] The physicochemical properties testing methods for the composite matrix prepared by this invention are as follows:

[0045] pH: Determined using the potentiometric method for determining soil pH (HJ 962-2018);

[0046] Electrical conductivity (EC): determined using the potentiometric method for the determination of soil electrical conductivity (HJ 802-2016);

[0047] Bulk density: determined using the ring cutter method;

[0048] Total porosity / ventilation porosity / water-holding porosity: determined using the soil core method (Tian et al.).

[0049] The testing method for physiological parameters of ryegrass cultured in the composite substrate prepared in this invention is as follows:

[0050] Germination rate: Count the number of germinated seeds and calculate it according to "germination rate = number of germinated seeds / total number of seeds × 100%", and take the average of 3 replicates;

[0051] Seedling height: The plant height was measured using a ruler, and the average value of 30 plants was taken, in cm.

[0052] Root length: The length of the taproot was measured using a ruler, and the average value of 30 plants was taken, in cm.

[0053] Fresh weight: The fresh weight of a single plant was determined using an electronic balance, and the average value of 30 plants was taken, in g.

[0054] A multi-granular iron tailings composite organic matrix, the components of which are as follows by weight:

[0055] 28-69 parts total tailings sand, 15-53 parts fine tailings and 15-22 parts agricultural organic matter;

[0056] Or 27-68 parts fine tailings sand, 16-51 parts fine tailings and 16-22 parts agricultural organic matter;

[0057] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer; wherein, the mass percentage of coconut coir is 20%; the mass percentage of pine bark is 20%; the mass percentage of perlite is 20%; the mass percentage of black soil is 20%; and the mass percentage of organic fertilizer is 20%.

[0058] The preparation method of the above-mentioned multi-granular iron tailings composite organic matrix includes the following steps:

[0059] (1) Using total tailings / fine tailings and fine tailings as inorganic raw materials, after impurity removal and drying treatment, the impurities are removed and the moisture content of inorganic raw materials is controlled (the moisture content of total tailings is 8.21%, the moisture content of fine tailings is 14.03%, and the moisture content of fine tailings is 32%).

[0060] (2) The agricultural organic fertilizer is pretreated, wherein: coconut coir, perlite and black soil are crushed and the moisture content is adjusted to 50-60%, pine bark is crushed to 3-5mm, and the organic fertilizer is sieved to remove impurities; then, it is added to the mixing equipment in the proportion and stirred evenly, and the moisture content of the agricultural organic fertilizer is adjusted to 55%;

[0061] (3) Premix the inorganic raw materials obtained in step (1) for 5-10 minutes (2000 r / min), then add the agricultural organic fertilizer obtained in step (2) and continue stirring for 10-15 minutes (2000 r / min). There is no extrusion or high temperature treatment throughout the process, and the natural pore structure is preserved. Finally, a multi-particle-size iron tailings composite matrix is ​​obtained.

[0062] Example 1

[0063] A multi-granular iron tailings composite organic matrix, the components of which are as follows by weight:

[0064] 28 samples of total tailings sand, 53 samples of fine-grained tailings, and 19 samples of agricultural organic matter;

[0065] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer; wherein, the mass percentage of coconut coir is 20%; the mass percentage of pine bark is 20%; the mass percentage of perlite is 20%; the mass percentage of black soil is 20%; and the mass percentage of organic fertilizer is 20%.

[0066] The preparation method of the above-mentioned multi-granular iron tailings composite organic matrix includes the following steps:

[0067] (1) Using total tailings sand and fine tailings as inorganic raw materials, impurities are removed and dried to control the moisture content of inorganic raw materials (the moisture content of total tailings sand is 8.21% and the moisture content of fine tailings is 32%).

[0068] (2) The agricultural organic matter is pretreated, including: coconut coir, perlite and black soil are crushed and the moisture content is adjusted to 50%, pine bark is crushed to 3mm, and organic fertilizer is sieved to remove impurities; then, it is added to the mixing equipment in the proportion and stirred evenly, and the moisture content of the agricultural organic fertilizer is adjusted to 55%;

[0069] (3) The inorganic raw materials obtained in step (1) are premixed (2000 r / min) for 10 min, and then the agricultural organic fertilizer obtained in step (2) is added. The mixture is stirred continuously (2000 r / min) for 15 min. There is no extrusion or high temperature treatment throughout the process, and the natural pore structure is preserved. Finally, a multi-particle-size iron tailings composite matrix is ​​obtained.

[0070] Example 2

[0071] A multi-granular iron tailings composite organic matrix, the components of which are as follows by weight:

[0072] 36 portions of total tailings sand, 49 portions of fine-grained tailings, and 15 portions of agricultural organic matter;

[0073] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer; wherein, the mass percentage of coconut coir is 20%; the mass percentage of pine bark is 20%; the mass percentage of perlite is 20%; the mass percentage of black soil is 20%; and the mass percentage of organic fertilizer is 20%.

[0074] The preparation method of the above-mentioned multi-granular iron tailings composite organic matrix is ​​the same as that in Example 1.

[0075] Example 3

[0076] A multi-granular iron tailings composite organic matrix, the components of which are as follows by weight:

[0077] 50 parts total tailings sand, 32 parts fine-grained tailings and 18 parts agricultural organic matter;

[0078] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer; wherein, the mass percentage of coconut coir is 20%; the mass percentage of pine bark is 20%; the mass percentage of perlite is 20%; the mass percentage of black soil is 20%; and the mass percentage of organic fertilizer is 20%.

[0079] The preparation method of the above-mentioned multi-granular iron tailings composite organic matrix is ​​the same as that in Example 1.

[0080] Example 4

[0081] A multi-granular iron tailings composite organic matrix, the components of which are as follows by weight:

[0082] 58 portions of total tailings sand, 20 portions of fine-grained tailings, and 22 portions of agricultural organic matter;

[0083] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer; wherein, the mass percentage of coconut coir is 20%; the mass percentage of pine bark is 20%; the mass percentage of perlite is 20%; the mass percentage of black soil is 20%; and the mass percentage of organic fertilizer is 20%.

[0084] The preparation method of the above-mentioned multi-granular iron tailings composite organic matrix is ​​the same as that in Example 1.

[0085] Example 5

[0086] A multi-granular iron tailings composite organic matrix, the components of which are as follows by weight:

[0087] 69 parts total tailings sand, 15 parts fine-grained tailings and 16 parts agricultural organic matter;

[0088] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer; wherein, the mass percentage of coconut coir is 20%; the mass percentage of pine bark is 20%; the mass percentage of perlite is 20%; the mass percentage of black soil is 20%; and the mass percentage of organic fertilizer is 20%.

[0089] The preparation method of the above-mentioned multi-granular iron tailings composite organic matrix is ​​the same as that in Example 1.

[0090] Example 6

[0091] A multi-granular iron tailings composite organic matrix, the components of which are as follows by weight:

[0092] 27 parts fine tailings sand, 51 parts fine-grained tailings and 22 parts agricultural organic matter;

[0093] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer; wherein, the mass percentage of coconut coir is 20%; the mass percentage of pine bark is 20%; the mass percentage of perlite is 20%; the mass percentage of black soil is 20%; and the mass percentage of organic fertilizer is 20%.

[0094] The preparation method of the above-mentioned multi-granular iron tailings composite organic matrix includes the following steps:

[0095] (1) Fine tailings sand and fine-grained tailings are used as inorganic raw materials. After impurity removal and drying, impurities are removed and the moisture content of inorganic raw materials is controlled (the moisture content of fine tailings sand is 14.03% and the moisture content of fine-grained tailings is 32%).

[0096] (2) The agricultural organic matter is pretreated, including: coconut coir, perlite and black soil are crushed and the moisture content is adjusted to 50%, pine bark is crushed to 3mm, and organic fertilizer is sieved to remove impurities; then, it is added to the mixing equipment in the proportion and stirred evenly, and the moisture content of the agricultural organic fertilizer is adjusted to 55%;

[0097] (3) The inorganic raw materials obtained in step (1) are premixed (2000 r / min) for 10 min, and then the agricultural organic fertilizer obtained in step (2) is added. The mixture is stirred continuously (2000 r / min) for 15 min. There is no extrusion or high temperature treatment throughout the process, and the natural pore structure is preserved. Finally, a multi-particle-size iron tailings composite matrix is ​​obtained.

[0098] Example 7

[0099] A multi-granular iron tailings composite organic matrix, the components of which are as follows by weight:

[0100] 38 parts fine tailings sand, 42 parts fine-grained tailings and 20 parts agricultural organic matter;

[0101] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer; wherein, the mass percentage of coconut coir is 20%; the mass percentage of pine bark is 20%; the mass percentage of perlite is 20%; the mass percentage of black soil is 20%; and the mass percentage of organic fertilizer is 20%.

[0102] The preparation method of the above-mentioned multi-granular iron tailings composite organic matrix is ​​the same as that in Example 6.

[0103] Example 8

[0104] A multi-granular iron tailings composite organic matrix, the components of which are as follows by weight:

[0105] 49 parts fine tailings sand, 33 parts fine tailings and 18 parts agricultural organic matter;

[0106] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer; wherein, the mass percentage of coconut coir is 20%; the mass percentage of pine bark is 20%; the mass percentage of perlite is 20%; the mass percentage of black soil is 20%; and the mass percentage of organic fertilizer is 20%.

[0107] The preparation method of the above-mentioned multi-granular iron tailings composite organic matrix is ​​the same as that in Example 6.

[0108] Example 9

[0109] A multi-granular iron tailings composite organic matrix, the components of which are as follows by weight:

[0110] 55 parts fine tailings sand, 28 parts fine-grained tailings and 17 parts agricultural organic matter;

[0111] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer; wherein, the mass percentage of coconut coir is 20%; the mass percentage of pine bark is 20%; the mass percentage of perlite is 20%; the mass percentage of black soil is 20%; and the mass percentage of organic fertilizer is 20%.

[0112] The preparation method of the above-mentioned multi-granular iron tailings composite organic matrix is ​​the same as that in Example 6.

[0113] Example 10

[0114] A multi-granular iron tailings composite organic matrix, the components of which are as follows by weight:

[0115] 68 parts fine tailings sand, 16 parts fine-grained tailings and 16 parts agricultural organic matter;

[0116] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer; wherein, the mass percentage of coconut coir is 20%; the mass percentage of pine bark is 20%; the mass percentage of perlite is 20%; the mass percentage of black soil is 20%; and the mass percentage of organic fertilizer is 20%.

[0117] The preparation method of the above-mentioned multi-granular iron tailings composite organic matrix is ​​the same as that in Example 6.

[0118] Comparative Example 1

[0119] A multi-granular iron tailings composite organic matrix, the components of which are as follows by weight:

[0120] 78 parts fine-grained tailings and 22 parts agricultural organic matter;

[0121] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer; wherein, the mass percentage of coconut coir is 20%; the mass percentage of pine bark is 20%; the mass percentage of perlite is 20%; the mass percentage of black soil is 20%; and the mass percentage of organic fertilizer is 20%.

[0122] Comparative Example 2

[0123] A multi-granular iron tailings composite organic matrix, the components of which are as follows by weight:

[0124] 85 samples of total tailings and 15 samples of agricultural organic matter;

[0125] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer; wherein, the mass percentage of coconut coir is 20%; the mass percentage of pine bark is 20%; the mass percentage of perlite is 20%; the mass percentage of black soil is 20%; and the mass percentage of organic fertilizer is 20%.

[0126] Comparative Example 3

[0127] A multi-granular iron tailings composite organic matrix, the components of which are as follows by weight:

[0128] 84 samples of fine tailings ore and 16 samples of agricultural organic matter;

[0129] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer; wherein, the mass percentage of coconut coir is 20%; the mass percentage of pine bark is 20%; the mass percentage of perlite is 20%; the mass percentage of black soil is 20%; and the mass percentage of organic fertilizer is 20%.

[0130] Comparative Example 4

[0131] Unlike Example 8, only the composition of agricultural organic matter was changed;

[0132] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer;

[0133] The composition of the ingredients is as follows: coconut coir accounts for 15% of the total weight; pine bark accounts for 15% of the total weight; perlite accounts for 20% of the total weight; black soil accounts for 20% of the total weight; and organic fertilizer accounts for 30% of the total weight.

[0134] Comparative Example 5

[0135] Unlike Example 8, only the composition of agricultural organic matter was changed;

[0136] The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer;

[0137] The composition of the ingredients is as follows: coconut coir accounts for 25% of the total weight; pine bark accounts for 25% of the total weight; perlite accounts for 20% of the total weight; black soil accounts for 20% of the total weight; and organic fertilizer accounts for 10% of the total weight.

[0138] Comparative Example 6

[0139] Unlike Example 8, only the composition of agricultural organic matter was changed;

[0140] The agricultural organic matter is composed of perlite, black soil and organic fertilizer;

[0141] The composition of the product is as follows: perlite accounts for 30% of the total mass; black soil accounts for 30% of the total mass; and organic fertilizer accounts for 40% of the total mass.

[0142] The bio-organic turf substrates prepared in Examples 1-10 and Comparative Examples 1-6 were tested for pH, electrical conductivity (EC), bulk density, total porosity, aeration porosity and water-holding porosity, respectively. The test results are shown in Table 1 below.

[0143] Table 1. Preparations obtained in Examples 1-10 and Comparative Examples 1-6

[0144] Physicochemical properties of biological organic turf substrate

[0145]

[0146] Analysis of Table 1 shows that, by comparing Examples 1-10, the composite matrices of Examples 1-5 (total tailings dredging system) and Examples 6-10 (fine tailings dredging system) are all weakly alkaline (pH 7.46-7.85), with significantly lower electrical conductivity than Comparative Example 1. Their bulk density and pore structure are within the range suitable for plant growth. As the ratio of total tailings dredging to fine tailings dredging increases, the matrix electrical conductivity decreases, the bulk density increases, the aeration porosity increases, and the water-holding porosity remains relatively stable. This indicates that the proportioning control of multi-size tailings can improve the physical and chemical properties of the matrix.

[0147] Comparing Example 4 with Comparative Example 1, it can be found that when no total tailings sand is added to the composite matrix system and only fine tailings are used as inorganic raw materials, the electrical conductivity of the entire composite matrix system is as high as 1277 μS / cm and the aeration porosity is only 1.47%, which is much lower than that of Example 4. This indicates that fine tailings alone are prone to salt accumulation and poor aeration. Adding total tailings sand can effectively improve the pore structure and reduce salt stress.

[0148] By comparing Example 2 and Comparative Example 2, it can be found that when no fine tailings are added to the composite matrix system and only total tailings dredged sand is used as the inorganic raw material, the water-holding porosity of the entire composite matrix system is only 32.31%, which is significantly lower than that of Example 2. This indicates that the water retention of total tailings dredged sand alone is poor, and the addition of fine tailings can make up for the water retention defect and promote the composite matrix system to achieve synergy between aeration and water retention.

[0149] By comparing Example 10 with Comparative Example 3, it can be found that when there is no fine tailings in the composite matrix system and only fine tailings sand is used as inorganic raw material, the total porosity and water-holding porosity are greatly reduced and the bulk density is too high. This indicates that the fine tailings sand alone will cause poor pore structure coordination. Combining it with fine tailings can optimize the pore structure of the entire composite matrix system.

[0150] By comparing Example 8 with Comparative Examples 4, 5 and 6, it can be found that when the proportion of organic fertilizer in Comparative Example 4 is increased and the proportion of organic fertilizer in Comparative Example 5 is decreased, the physicochemical properties of the composite substrate do not change significantly, but the germination rate of plants cultured in the composite substrate is affected. In Comparative Example 6, no coconut coir or pine bark was added to the formula, and the aeration porosity of the substrate decreased to 6.25%, and the pore structure deteriorated. This indicates that appropriate coconut coir and pine bark are crucial to improving the aeration of the composite substrate, and the five-element ratio of agricultural organic matter is the optimal ratio.

[0151] The bio-organic turfgrass substrates prepared in Examples 1-10 and Comparative Examples 1-6 were used to cultivate ryegrass, and the cultivation methods are as follows:

[0152] Fill 2.5L / pot flowerpots with the composite substrate, level it without squeezing, and sow 100 perennial ryegrass seeds in each pot; place the flowerpots on a cultivation rack and cultivate them, controlling the light intensity to 2.0 × 10⁻⁶. 4 Lux, light duration 8h / d (8:00~16:00); water 20mL twice a day, morning and evening, no additional fertilizer applied, cultivation period 20 days.

[0153] Ryegrass cultured in the bio-organic turfgrass substrates prepared in Examples 1-10 and Comparative Examples 1-6 were tested for various physiological indicators (germination rate (%), seedling height (cm), root length (cm) and fresh weight per plant (g)). The test results are shown in Table 2 below.

[0154] Table 2. Preparations of Examples 1-10 and Comparative Examples 1-6

[0155] Results of physiological index tests on various plants cultured in biological organic turf substrate

[0156]

[0157] Analysis of Table 2 shows that the germination rate, seedling height, root length, and fresh weight of ryegrass in Examples 1-10 were significantly improved. Among them, the ryegrass cultured in the composite substrate prepared in Example 8 (49 parts fine tailings sand + 33 parts fine tailings + 18 parts agricultural organic matter) had the best physiological indicators, with a germination rate of 44.0% and the highest seedling height, root length, and fresh weight. As the ratio of total tailings sand to fine tailings sand increased, the physiological indicators of ryegrass showed a trend of first increasing and then decreasing, indicating that there is an optimal ratio range for multi-granular tailings.

[0158] Comparing Example 4 with Comparative Example 1, it can be found that the germination rate of ryegrass in Comparative Example 1 was only 17.0%, and the seedling height, root length and fresh weight were much lower than those in Example 4. This indicates that the substrate prepared by fine tailings alone severely inhibited the germination and growth of ryegrass due to poor aeration and salt stress.

[0159] The comparison between Example 2 and Comparative Example 2 shows that the physiological indicators of ryegrass in Comparative Example 2 are significantly lower than those in Example 2, indicating that the substrate prepared by the tailings sand alone has poor water retention and cannot provide sufficient water for the growth of ryegrass, resulting in poor growth.

[0160] The comparison between Example 10 and Comparative Example 3 shows that the germination rate and growth of ryegrass in Comparative Example 3 are both poor, indicating that the pore structure and water retention of fine-tailed sand are insufficient when used alone, which limits the growth of plant roots.

[0161] Comparing Example 8 with Comparative Examples 4, 5, and 6, it can be found that in Comparative Example 4, increasing the proportion of organic fertilizer slightly reduced the physiological indicators of ryegrass cultured in the prepared composite substrate; in Comparative Example 5, reducing the proportion of organic fertilizer resulted in insufficient nutrients in the prepared composite substrate, leading to a poorer germination rate and growth; and in Comparative Example 6, the formula did not contain coconut coir or pine bark, resulting in poor aeration and a germination rate of only 28.6%. This indicates that the five-element ratio of agricultural organic matter in this invention (coconut coir: pine bark: perlite: black soil: organic fertilizer = 1:1:1:1:1) is the optimal ratio, which can maximize the improvement of plant adaptability.

Claims

1. A multi-granularity iron tailings composite organic matrix, characterized in that, By weight, the components are as follows: 28-69 parts total tailings sand, 15-53 parts fine tailings and 15-22 parts agricultural organic matter; Or 27-68 parts fine tailings sand, 16-51 parts fine tailings and 16-22 parts agricultural organic matter; The agricultural organic matter is composed of coconut coir, pine bark, perlite, black soil, and organic fertilizer; wherein, the mass percentage of coconut coir is 20%; the mass percentage of pine bark is 20%; the mass percentage of perlite is 20%; the mass percentage of black soil is 20%; and the mass percentage of organic fertilizer is 20%.

2. The multi-granularity iron tailings composite organic matrix according to claim 1, characterized in that, By weight, the components are as follows: 58 parts total tailings sand, 20 parts fine tailings and 22 parts agricultural organic matter; Or 49 parts fine tailings sand, 33 parts fine tailings and 18 parts agricultural organic matter.

3. The multi-granularity iron tailings composite organic matrix according to claim 1, characterized in that, The total tailings dredged sand, by mass percentage, comprises 54.65% SiO2, 19.18% Al2O3, and 7.13% Na2O; the particle size of the total tailings dredged sand is ≤4mm.

4. The multi-granularity iron tailings composite organic matrix according to claim 1, characterized in that, The fine tailings sand, by mass percentage, comprises 57.43% SiO2, 19.43% Al2O3, and 6.55% Na2O; the particle size of the fine tailings sand is ≤4mm.

5. The multi-granularity iron tailings composite organic matrix according to claim 1, characterized in that, The fine-grained tailings, by mass percentage, comprise 53.86% SiO2, 18.55% Al2O3, and 9.97% Fe2O3; the particle size of the fine-grained tailings is -200 mesh.

6. A method for preparing a multi-granularity iron tailings composite organic matrix as described in any one of claims 1 to 5, characterized in that, The steps are as follows: S1: Using total tailings / fine tailings and fine-grained tailings as inorganic raw materials, the materials are treated by impurity removal and drying to remove impurities and control the moisture content of the inorganic raw materials. S2: Pre-treat the agricultural organic fertilizer, then add it to the mixing equipment according to the ratio and stir evenly to adjust the moisture content of the agricultural organic fertilizer; S3: Premix the inorganic raw materials obtained from S1 for 5-10 minutes, then add the agricultural organic fertilizer obtained from S2 pretreatment, and continue stirring for 10-15 minutes. There is no extrusion or high-temperature treatment throughout the process, and the natural porous structure is preserved to finally obtain a multi-particle-size iron tailings composite matrix.

7. The method for preparing the multi-granular iron tailings composite organic matrix according to claim 6, characterized in that, In S1, the moisture content is specifically controlled as follows: the total tailings moisture content is 8.21%, the fine tailings moisture content is 14.03%, and the fine-grained tailings moisture content is 32%.

8. The method for preparing the multi-granular iron tailings composite organic matrix according to claim 6, characterized in that, In S2, the pretreatment includes: crushing coconut coir, perlite and black soil and adjusting the moisture content to 50-60%; crushing pine bark to 3-5mm; sieving organic fertilizer to remove impurities; and adjusting the moisture content of agricultural organic fertilizer to 55%.

9. The application of the multi-granular iron tailings composite organic matrix according to any one of claims 1 to 5 in the cultivation of ryegrass plants.

10. The application according to claim 9, characterized in that, The cultivation method is as follows: Fill 2.5L / pot flowerpots with the composite substrate, level it without squeezing, and sow 100 perennial ryegrass seeds in each pot; place the flowerpots on a cultivation rack and cultivate them, controlling the light intensity to 2.0 × 10⁻⁶. 4 Lux, light duration 8h / d (8:00~16:00); water 20mL twice a day, morning and evening, no additional fertilizer applied, cultivation period 20 days.

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