Organic modifier as well as preparation method and application thereof

Abstract

The invention relates to the technical field of fertilizers, and particularly discloses an organic modifier as well as a preparation method and application thereof. The organic improver provided by the invention is prepared from the following components in parts by mass: 30 to 35 parts of modified sludge, 20 to 25 parts of modified vermiculite, 15 to 18 parts of a chitosan-modified fly ash composite material and 22 to 25 parts of decomposed sawdust. In the organic modifier provided by the invention, the modified sludge, the modified vermiculite, the chitosan-modified fly ash composite material and the decomposed sawdust jointly improve the soil containing the iron tailing sand, and all the components play a synergistic effect; by reducing the content of heavy metal ions in the soil, increasing the content of available elements of plants and improving the water and fertilizer retention capacity of the soil, the problem that plants in the existing iron-containing tailing sand soil are difficult to grow is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of fertilizers, and in particular to an organic improver and a preparation method and application thereof. Background Art

[0002] Iron tailings are the solid waste left after iron ore is mined, crushed, ground, and subjected to a series of beneficiation processes such as magnetic separation, flotation, and gravity separation to extract iron concentrate. The production process begins when the iron ore is mined out of the mine, and then undergoes a number of complex processes in the beneficiation plant, where iron and other valuable components are gradually separated and enriched, eventually forming iron tailings. At present, the treatment of iron tailings has encountered many bottlenecks. On the one hand, the treatment cost remains high, and the accumulation of a large amount of iron tailings not only occupies vast land, but also requires high maintenance and management costs for the accumulation site; on the other hand, the existing treatment technology is difficult to balance high efficiency and environmental protection, and it is difficult to fully tap the potential value of iron tailings, resulting in a large amount of iron tailings being idle for a long time. At present, there are also greening treatments for iron tailings in mines. However, due to the rough texture and large pores of iron tailings, their water and fertilizer retention capacity is almost zero, and they cannot provide a continuous and stable supply of water and nutrients for plant growth. In addition, harmful substances such as heavy metals remaining in iron tailings will strongly inhibit or even poison plants, hindering their normal growth, and these harmful substances will migrate and spread with the natural cycle, polluting the surrounding ecosystem. In addition, the pH value of iron tailings is usually contrary to the suitable growth range of plants, and there is a lack of good soil structure suitable for plant roots to take root and extend, resulting in a scarcity of plant species suitable for growing on iron tailings, which seriously restricts the smooth progress and effectiveness of iron tailings greening work. Summary of the invention

[0003] In view of this, the present invention provides an organic improver and a preparation method and application thereof.

[0004] In order to solve the above technical problems, the technical solution provided by the present invention is: The present invention provides an organic improver, comprising the following components in parts by weight: 30 to 35 parts of modified sludge, 20 to 25 parts of modified vermiculite, 15 to 18 parts of chitosan-modified fly ash composite material and 22 to 25 parts of decomposed sawdust; Wherein, the modified sludge is obtained by mixing sludge and calcium oxide and then heating; The modified vermiculite is obtained by sequentially subjecting vermiculite to modification with a first silane coupling agent and calcination treatment; The modified fly ash in the chitosan-modified fly ash composite material is obtained by microwave treatment of fly ash.

[0005] At present, the main means to promote plant growth on iron tailings include plant selection and soil improvement. In the way of plant selection, the survival rate is mainly improved by selecting stress-tolerant plants or pioneer plants. However, although stress-tolerant plants and pioneer plants have strong adaptability, their growth rate is slow and the ecological restoration period is long. Therefore, some people also promote plant growth on iron tailings by using soil conditioners, improving the soil structure and nutrients by adding organic substances and adjusting the pH value. However, after the organic substances in the existing conditioners are doped into the soil containing iron tailings, although the growth of plants is better than that using only iron tailings, it is far from the expected effect. Therefore, it is of great significance to provide an organic conditioner to promote the growth of green plants on iron tailings.

[0006] Compared with the prior art, in the organic conditioner provided by the present invention, the modified sludge is obtained by modifying the sludge with calcium oxide and then heating it at high temperature. First, calcium oxide and the sludge are mixed. Calcium oxide not only plays a role in sterilizing the sludge, but also part of calcium oxide dissolves in water to form calcium hydroxide, which can also react with heavy metal ions in the sludge to form stable precipitates. The alkaline conditions provided by calcium oxide also promote the formation of stable mineral phases by some heavy metal ions and other ions in the sludge, converting the heavy metal ions into a stable state and reducing the absorption rate of plants for heavy metals. By reducing the heavy metal stress of plants, the growth of plants is promoted. The sludge treated with calcium oxide is heated at high temperature to form sludge with a stable porous structure, which is added to the organic conditioner system to achieve the effects of ventilation and water retention, greatly promoting the growth of plants. In addition, after mixing calcium oxide and the sludge and then heating them at high temperature, the release of elements essential for plant growth such as nitrogen, phosphorus and potassium in the sludge is also greatly stimulated, thereby improving the growth of plants on the soil of iron tailings sand. Calcium oxide will first react to form calcium hydroxide, and further after high-temperature treatment, calcium hydroxide will dehydrate to form calcium oxide. When it is added to iron tailings sand, in the natural environment, part of calcium oxide absorbs water to produce calcium hydroxide, which can also react with heavy metal ions in the iron tailings sand, reducing the content of heavy metal ions in the iron tailings sand soil, thereby reducing the stress on plant roots and promoting plant growth. When the soil is acidic, calcium oxide can also adjust the pH of the iron tailings sand to make the iron tailings sand soil reach the optimal pH for plant growth, further promoting plant growth.

[0007] After treating vermiculite with the first silane coupling agent, the first silane coupling agent can react with the active groups on the surface of vermiculite to form stable covalent bonds, tightly connecting the first silane coupling agent and vermiculite together. Moreover, the active groups on the first silane coupling agent can also react with the active groups in the iron tailings sand soil, enhancing the binding force between vermiculite and other components and soil particles, thereby avoiding the agglomeration phenomenon of modified vermiculite. Further calcining the vermiculite treated with the first silane coupling agent can further enhance the internal voids of vermiculite, making its structure more porous, and also making the interlayer structure of vermiculite more stable. The calcined layered structure endows vermiculite with excellent adsorption performance and ion exchange performance. Adding the modified vermiculite to the iron tailings sand soil endows it with the ability to store a large amount of water and fertilizers, significantly improving the poor water and fertilizer retention capacity of the iron tailings sand soil, optimizing the growth environment of plant roots, and promoting the growth of plants in the iron tailings sand.

[0008] In the chitosan-modified fly ash composite material, microwave treatment of fly ash can change the crystal grain structure of fly ash, greatly increasing the specific surface area of fly ash. By improving the structure of the iron tailings sand soil, the water and fertilizer retention performance of the iron tailings sand soil is improved, thereby promoting the growth of plants. Moreover, the microwave treatment process can further activate fly ash, releasing various trace elements such as silicon, aluminum, and iron, providing additional nutrient elements for the better growth of plants. The fly ash treated by microwave can be evenly dispersed in the iron tailings sand soil. When the modified fly ash and chitosan are compounded, chitosan is loaded on the surface of fly ash and evenly dispersed in the soil, forming a protective film on the surface of soil particles, to a certain extent avoiding the problem of too fast evaporation of water in the soil, achieving the water retention effect and promoting plant growth. The decomposed wood chips can promote plant growth by continuously releasing organic matter and enhancing the air permeability of the iron tailings sand soil.

[0009] In the organic modifier provided by the present invention, the modified sludge, modified vermiculite, chitosan-modified fly ash composite material, and decomposed wood chips jointly improve the iron tailings sand soil, and each component plays a synergistic effect. By reducing the content of heavy metal ions in the soil, increasing the content of plant-available elements, and improving the water and fertilizer retention capacity of the soil, the problem of difficult plant growth in the existing iron tailings sand soil is solved.

[0010] The preparation method of the modified sludge includes the following steps: Step a: Add the calcium oxide to the sludge and keep it warm at 35°C to 45°C to obtain a mixed sludge; Step b: Centrifuge and concentrate the mixed sludge, heat it to 680°C to 700°C at a rate of 200°C / s to 300°C / s, and then keep it warm to obtain the modified sludge.

[0011] The method for modifying sludge provided by the present invention mixes calcium oxide and sludge at a specific temperature for heat preservation, which can fully sterilize and also cause heavy metal ions in the sludge to react, reducing the stress of heavy metals on plant growth. Further, the present invention heats up to a specific temperature at a specific heating rate for heat preservation, which is beneficial to the combination of calcium oxide and sludge, and the sludge will be rapidly carbonized to form a stable porous structure. Calcium oxide is loaded on the porous structure and surface of the sludge. The calcium oxide on the surface absorbs water to form calcium hydroxide, which will react with heavy metals in the iron tailings sand, reducing the stress of heavy metals on plants. The calcium oxide in the porous structure further plays a role in sterilization. At the same time, it can also adjust the soil pH and promote plant growth through multiple effects. At the same time, heat preservation at a specific temperature can also ensure the release of nutrient elements in the sludge.

[0012] Preferably, in step a, the particle size of the calcium oxide is 200 μm to 300 μm.

[0013] Preferably, in step a, the water content of the sludge is 30 wt% to 35 wt%.

[0014] Preferably, in step a, the mass ratio of the calcium oxide to the sludge is 1:(7 - 9).

[0015] Preferably, in step a, the heat preservation time is 4 d to 6 d.

[0016] Preferably, in step a, stirring treatment is also required during heat preservation.

[0017] Preferably, in step b, the conditions for centrifugal concentration are: the water content of the mixed sludge after centrifugal concentration < 5%.

[0018] Preferably, in step b, the heat preservation time is 15 min to 30 min.

[0019] The preparation method of the modified vermiculite includes the following steps: S1. Add the vermiculite into the first silane coupling agent and keep it at 50°C to 60°C for heat preservation to obtain the first treated vermiculite; S2. Calcinate the first treated vermiculite at 400°C to 450°C to obtain the modified vermiculite.

[0020] The preparation method of the modified vermiculite provided by the present invention mainly includes coupling treatment and calcination treatment. The preparation method is simple, and the process is easier to operate and control. On the basis of reducing production costs, it also solves the problem of vermiculite agglomeration, and greatly improves the stability of the vermiculite structure, enabling the modified vermiculite to have excellent adsorption performance and ion exchange performance, endowing the modified vermiculite with excellent water storage and fertilizer retention capabilities, thereby promoting plant growth in iron tailings sand.

[0021] Preferably, in S1, the first silane coupling agent is γ-glycidoxypropyltrimethoxysilane.

[0022] Preferably, in S1, the mass ratio of the vermiculite to the first silane coupling agent is (4 - 5):1.

[0023] Preferably, in S1, the heat preservation time is 2h - 3h.

[0024] Preferably, in S2, the calcination time is 40min - 60min.

[0025] Preferably, in S2, the particle size of the modified vermiculite is 100 - 130 mesh.

[0026] Preferably, the preparation method of the chitosan-modified fly ash composite material comprises the following steps: Step 1: Disperse chitosan in water to obtain a chitosan dispersion; Step 2: Perform microwave treatment on the fly ash to obtain modified fly ash; Step 3: Add the modified fly ash and the second silane coupling agent to the chitosan dispersion, perform heat preservation at 50°C - 70°C, wash, dry, and perform solid-liquid separation to obtain the chitosan-modified fly ash composite material.

[0027] The composite material obtained by only compounding fly ash and chitosan still has limited effect on the growth of plants in iron tailings sand. Through a large number of experiments during the research process, the inventors found that when the fly ash is subjected to microwave treatment, not only does the specific surface area of the fly ash increase, which can improve the soil structure of iron tailings sand, but also the active components are activated, further releasing a large amount of trace elements. When it is compounded with chitosan, it can promote the growth of plants by providing trace elements for plant growth and improving the water retention of the soil.

[0028] Preferably, in Step 1, the mass concentration of the chitosan dispersion is 1% - 1.5%.

[0029] Preferably, in Step 2, the particle size of the fly ash is 130 - 150 mesh.

[0030] Preferably, in Step 2, the conditions of the microwave are: power 500W - 800W, time 4min - 6min.

[0031] Preferably, in Step 3, the second silane coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0032] Preferably, in Step 3, the mass ratio of the modified fly ash to the second silane coupling agent is 100:(1 - 2).

[0033] Preferably, in step 3, the heat preservation time is 60 min to 70 min.

[0034] Preferably, the mass ratio of chitosan to modified fly ash in the chitosan-modified fly ash composite material is 1:(5 - 7).

[0035] Preferably, in step 3, the particle size of the chitosan-modified fly ash composite material is 2 mm to 5 mm.

[0036] Preferably, the carbon-nitrogen ratio of the decomposed wood chips is (25 - 30):1.

[0037] The second aspect of the present invention provides a preparation method of the above organic modifier, including the following steps: Mix the weighed modified sludge, modified vermiculite, chitosan-modified fly ash composite material and decomposed wood chips evenly to obtain the organic modifier.

[0038] The third aspect of the present invention provides the application of the above organic modifier or the organic modifier prepared by the preparation method of the above organic modifier in improving iron tailings sand soil. Specific embodiments

[0039] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] To better illustrate the present invention, further examples are given below through embodiments.

[0041] Example 1 This example provides an organic modifier, including the following components in parts by mass: 30 parts of modified sludge, 25 parts of modified vermiculite, 18 parts of chitosan-modified fly ash composite material and 22 parts of decomposed wood chips; The preparation method of the modified sludge includes the following steps: Step a: Add calcium oxide with a particle size of 200 μm to sludge with a water content of 30 wt%, keep it warm at 35 °C for 4 d, and stir during heat preservation to obtain mixed sludge; the mass ratio of calcium oxide to sludge is 1:7; Step b: Centrifuge and concentrate the mixed sludge to a water content of 3%, heat it up to 700 °C at a rate of 300 °C / s, and then keep it warm for 30 min to obtain the modified sludge; The preparation method of the modified vermiculite includes the following steps: S1: Add vermiculite to γ-glycidoxypropyltrimethoxysilane, keep it warm at 60 °C for 2 h to obtain the first treated vermiculite; the mass ratio of vermiculite to γ-glycidoxypropyltrimethoxysilane is 4:1; S2. Calcinate the first treated vermiculite at 400 °C for 40 min, and grind it to a particle size of 130 mesh to obtain modified vermiculite; The preparation method of the chitosan-modified fly ash composite material comprises the following steps: Step 1. Disperse chitosan in water to obtain a chitosan dispersion with a mass concentration of 1%; Step 2. Perform microwave treatment on fly ash with a particle size of 130 mesh, control the power at 500 W, and the time at 4 min to obtain modified fly ash; Step 3. Add the modified fly ash and γ-(2,3-epoxypropoxy)propyltrimethoxysilane to the chitosan dispersion, keep it warm at 50 °C for 60 min, wash, dry, and perform solid-liquid separation to obtain a chitosan-modified fly ash composite material with a particle size of 2 mm; the mass ratio of the modified fly ash to γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 100:1, and the mass ratio of chitosan to the modified fly ash is 1:7; The carbon-nitrogen ratio of the decomposed sawdust is 25:1.

[0042] This example also provides a preparation method of the above organic conditioner, which comprises the following steps: Mix the weighed modified sludge, modified vermiculite, chitosan-modified fly ash composite material and decomposed sawdust evenly to obtain the organic conditioner.

[0043] Example 2 This example provides an organic conditioner, which comprises the following components in parts by mass: 35 parts of modified sludge, 20 parts of modified vermiculite, 15 parts of chitosan-modified fly ash composite material and 25 parts of decomposed sawdust; The preparation method of the modified sludge comprises the following steps: Step a. Add calcium oxide with a particle size of 300 μm to sludge with a water content of 35 wt%, keep it warm at 45 °C for 6 d, and stir during the heat preservation to obtain a mixed sludge; the mass ratio of calcium oxide to sludge is 1:9; Step b. Centrifuge and concentrate the mixed sludge to a water content of 2%, heat it up to 680 °C at a rate of 200 °C / s, and then keep it warm for 15 min to obtain the modified sludge; The preparation method of the modified vermiculite comprises the following steps: S1. Add vermiculite to γ-glycidyletheroxypropyltrimethoxysilane, keep it warm at 50 °C for 3 h to obtain the first treated vermiculite; the mass ratio of vermiculite to γ-glycidyletheroxypropyltrimethoxysilane is 5:1; S2. Calcinate the first treated vermiculite at 450 °C for 60 min, and grind it to a particle size of 100 mesh to obtain modified vermiculite; The preparation method of the chitosan-modified fly ash composite material comprises the following steps: Step 1: Disperse chitosan in water to obtain a chitosan dispersion with a mass concentration of 1.5%. Step 2: Perform microwave treatment on fly ash with a particle size of 150 mesh, control the power at 800 W and the time at 6 min to obtain modified fly ash. Step 3: Add the modified fly ash and γ-(2,3-epoxypropoxy)propyltrimethoxysilane to the chitosan dispersion, keep it warm at 70 °C for 70 min, wash, dry, and perform solid-liquid separation to obtain a chitosan-modified fly ash composite with a particle size of 5 mm; the mass ratio of the modified fly ash to γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 100:2, and the mass ratio of chitosan to the modified fly ash is 1:5. The carbon-nitrogen ratio of the decomposed sawdust is 30:1.

[0044] This example also provides a preparation method of the above organic conditioner, including the following steps: Mix the weighed modified sludge, modified vermiculite, chitosan-modified fly ash composite and decomposed sawdust evenly to obtain the organic conditioner.

[0045] Example 3 This example provides an organic conditioner, including the following components in parts by mass: 32 parts of modified sludge, 24 parts of modified vermiculite, 17 parts of chitosan-modified fly ash composite and 23 parts of decomposed sawdust; The preparation method of the modified sludge includes the following steps: Step a: Add calcium oxide with a particle size of 250 μm to sludge with a water content of 33 wt%, keep it warm at 40 °C for 5 d, and stir during the heat preservation to obtain a mixed sludge; the mass ratio of calcium oxide to sludge is 1:8; Step b: Centrifuge and concentrate the mixed sludge to a water content of 4%, heat it up to 690 °C at a rate of 250 °C / s, and then keep it warm for 25 min to obtain the modified sludge; The preparation method of the modified vermiculite includes the following steps: S1: Add vermiculite to γ-glycidyletheroxypropyltrimethoxysilane, keep it warm at 55 °C for 2.5 h to obtain the first treated vermiculite; the mass ratio of vermiculite to γ-glycidyletheroxypropyltrimethoxysilane is 4.5:1; S2: Calcinate the first treated vermiculite at 430 °C for 50 min and grind it to a particle size of 120 mesh to obtain the modified vermiculite; The preparation method of the chitosan-modified fly ash composite includes the following steps: Step 1: Disperse chitosan in water to obtain a chitosan dispersion with a mass concentration of 1.3%. Step 2: Perform microwave treatment on fly ash with a particle size of 140 mesh, control the power at 600 W and the time at 5 min to obtain modified fly ash. Step 3: Add the modified fly ash and γ-(2,3-epoxypropoxy)propyltrimethoxysilane into the chitosan dispersion liquid, keep it warm at 60°C for 65 minutes, wash, dry, and perform solid-liquid separation to obtain a chitosan-modified fly ash composite material with a particle size of 4 mm; the mass ratio of the modified fly ash to γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 100:1.5, and the mass ratio of chitosan to the modified fly ash is 1:6; The carbon-nitrogen ratio of the decomposed wood chips is 28:1.

[0046] This example also provides a preparation method of the above organic modifier, including the following steps: Mix the weighed modified sludge, modified vermiculite, chitosan-modified fly ash composite material and decomposed wood chips evenly to obtain the organic modifier.

[0047] Example 4 This example provides an organic modifier. The difference between this example and Example 1 is that when preparing the modified vermiculite, in S2, the calcination temperature is 500°C, and other operation steps are the same as those in Example 1.

[0048] Example 5 This example provides an organic modifier. The difference between this example and Example 1 is that when preparing the modified sludge, in step b, the temperature is raised to 700°C at a rate of 100°C / s, and other operation steps are the same as those in Example 1.

[0049] Comparative Example 1 Compared with Example 1, the difference between this comparative example and Example 1 is that when preparing the modified sludge, calcium oxide is replaced with an equal amount of magnesium oxide. Specifically, the preparation method of the modified sludge includes the following steps: Step a: Add magnesium oxide with a particle size of 200 μm into the sludge with a water content of 30 wt%, keep it warm at 35°C for 4 days, and stir during the warming process to obtain a mixed sludge; the mass ratio of magnesium oxide to the sludge is 1:7; Step b: Centrifuge and concentrate the mixed sludge to a water content of 3%, raise the temperature to 700°C at a rate of 300°C / s, and then keep it warm for 30 minutes to obtain the modified sludge; other operation steps are the same as those in Example 1.

[0050] Comparative Example 2 Compared with Example 1, the difference between this comparative example and Example 1 is that when preparing the modified vermiculite, no calcination treatment is performed. Specifically, add vermiculite into γ-glycidyletheroxypropyltrimethoxysilane, keep it warm at 60°C for 2 hours to obtain the modified vermiculite; the mass ratio of vermiculite to γ-glycidyletheroxypropyltrimethoxysilane is 4:1; other operation steps are the same as those in Example 1.

[0051] Comparative Example 3 Compared with Example 1, the difference between this comparative example and Example 1 is that when preparing the chitosan-fly ash composite material, the fly ash is not subjected to microwave treatment. Specifically as follows: The preparation method of the chitosan-fly ash composite material includes the following steps: Step 1: Disperse chitosan in water to obtain a chitosan dispersion with a mass concentration of 1%. Step 2: Add fly ash and γ-(2,3-epoxypropoxy)propyltrimethoxysilane into the chitosan dispersion, keep it warm at 50°C for 60 min, wash, dry, and perform solid-liquid separation to obtain a chitosan-fly ash composite material with a particle size of 2 mm. The mass ratio of fly ash to γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 100:1, and the mass ratio of chitosan to fly ash is 1:7. Other operation steps are the same as those in Example 1.

[0052] Comparative Example 4 Compared with Example 1, the difference between this comparative example and Example 1 is that fly ash is replaced with an equal amount of diatomite. Specifically as follows: The preparation method of the chitosan-modified diatomite composite material includes the following steps: Step 1: Disperse chitosan in water to obtain a chitosan dispersion with a mass concentration of 1%. Step 2: Perform microwave treatment on diatomite with a particle size of 130 mesh, control the power at 500 W, and the time at 4 min to obtain modified diatomite. Step 3: Add the modified diatomite and γ-(2,3-epoxypropoxy)propyltrimethoxysilane into the chitosan dispersion, keep it warm at 50°C for 60 min, wash, dry, and perform solid-liquid separation to obtain a chitosan-modified diatomite composite material with a particle size of 2 mm. The mass ratio of the modified diatomite to γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 100:1, and the mass ratio of chitosan to the modified diatomite is 1:7. Other operation steps are the same as those in Example 1.

[0053] Comparative Example 5 Compared with Example 1, the difference between this comparative example and Example 1 is that chitosan is replaced with an equal amount of sodium alginate. Specifically as follows: The preparation method of the sodium alginate-modified fly ash composite material includes the following steps: Step 1: Disperse sodium alginate in water to obtain a sodium alginate dispersion with a mass concentration of 1%. Step 2: Perform microwave treatment on fly ash with a particle size of 130 mesh, control the power at 500 W, and the time at 4 min to obtain modified fly ash. Step 3: Add the modified fly ash and γ-(2,3-epoxypropoxy)propyltrimethoxysilane into the sodium alginate dispersion, keep it warm at 50°C for 60 min, wash, dry, perform solid-liquid separation to obtain a sodium alginate-modified fly ash composite material with a particle size of 2 mm; the mass ratio of the modified fly ash to γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 100:1, and the mass ratio of sodium alginate to the modified fly ash is 1:7; Other operation steps are the same as those in Example 1.

[0054] Application Example Prepare planting soil by configuring iron tailings sand, the organic modifiers prepared in Examples 1-5 and Comparative Examples 1-5, and soil according to a mass ratio of 0.3:0.3:1. Fill the planting soil of each treatment into plastic pots (the diameter of the pot mouth is 14 cm, the height is 12 cm, and the diameter of the pot bottom is 10 cm). Before sowing, detect the total porosity and bulk density of the planting soil. Select the seeds of creeping bentgrass and plant them in the plastic pots, sowing 0.5 g per pot. Evenly spread the weighed seeds on the plastic pots with the prepared substrate, and repeat each treatment 3 times. After sufficient watering, cover it with non-woven fabric and place it in a greenhouse at a temperature of 24±5°C, a humidity of 60%-70%, and a light time of 13-15 h for cultivation. Measure the plant height of creeping bentgrass on the 40th day after sowing, and measure the root length of creeping bentgrass after 6 months; among them, the detection methods for porosity and bulk density are both the core cutter method; the specific detection results are shown in Table 1: Table 1

[0055] As can be seen from Table 1, for the planting soil improved by the organic modifier provided in the embodiments of the present invention, after planting creeping bentgrass, the plant height on the 40th day is significantly higher than that of Comparative Examples 1-5, and the root length is also significantly longer than that of Comparative Examples 1-5. The total porosity and bulk density are both better than those of Comparative Examples 1-5. This proves that the organic modifier provided in the embodiments of the present invention can promote the growth of plants, and the plant height and root length are significantly better than those of Comparative Examples 1-5; in Comparative Example 1 of the present invention, calcium oxide is replaced with an equal amount of magnesium oxide during the preparation of the modified sludge, in Comparative Example 2, no calcination treatment is performed during the preparation of the modified vermiculite, in Comparative Example 3, no microwave treatment is performed on the fly ash during the preparation of the chitosan-fly ash composite material, in Comparative Example 4, fly ash is replaced with an equal amount of diatomite, and in Comparative Example 5, chitosan is replaced with an equal amount of sodium alginate. The results in Table 1 show that no matter any condition in Example 1 is changed, the comparative experiment affects the soil structure and changes the soil void situation to a certain extent, thereby affecting the growth of plants in the iron tailings sand planting soil.

[0056] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An organic modifier, characterized in that It comprises the following components in parts by mass: 30 to 35 parts of modified sludge, 20 to 25 parts of modified vermiculite, 15 to 18 parts of chitosan-modified fly ash composite, and 22 to 25 parts of decomposed wood chips; Among them, the modified sludge is obtained by heating the mixture of sludge and calcium oxide; The modified vermiculite is obtained by modifying vermiculite with a first silane coupling agent and then performing calcination treatment; In the chitosan-modified fly ash composite, the modified fly ash is obtained by microwave treatment of fly ash.

2. The organic modifier according to claim 1, wherein The preparation method of the modified sludge comprises the following steps: Step a: Add the calcium oxide to the sludge and keep it warm at 35°C to 45°C to obtain a mixed sludge; Step b: Centrifuge and concentrate the mixed sludge, heat it to 680°C to 700°C at a rate of 200°C / s to 300°C / s, and then keep it warm to obtain the modified sludge.

3. The organic modifier according to claim 2, characterized in that, In step a, the particle size of the calcium oxide is 200μm to 300μm; and / or In step a, the water content of the sludge is 30wt% to 35wt%; and / or In step a, the mass ratio of the calcium oxide to the sludge is 1:(7 - 9); and / or In step a, the heat preservation time is 4d to 6d.

4. The organic modifier according to claim 2, characterized in that, In step b, the heat preservation time is 15min to 30min.

5. The organic modifier according to claim 1, wherein, The preparation method of the modified vermiculite comprises the following steps: S1: Add the vermiculite to the first silane coupling agent and keep it warm at 50°C to 60°C to obtain the first treated vermiculite; S2: Calcinate the first treated vermiculite at 400°C to 450°C to obtain the modified vermiculite.

6. The organic modifier according to claim 5, wherein, In S1, the first silane coupling agent is γ-glycidoxypropyltrimethoxysilane; and / or In S1, the mass ratio of the vermiculite to the first silane coupling agent is (4 - 5):1; and / or In S1, the heat preservation time is 2h to 3h; and / or In S2, the calcination time is 40min to 60min.

7. The organic modifier according to claim 1, characterized in that, The preparation method of the chitosan-modified fly ash composite comprises the following steps: Step 1: Disperse the chitosan solution in water to obtain a chitosan dispersion; Step 2: Perform microwave treatment on the fly ash to obtain modified fly ash; Step 3: Add the modified fly ash and a second silane coupling agent to the chitosan dispersion, keep it warm at 50°C to 70°C, wash, dry, and perform solid-liquid separation to obtain the chitosan-modified fly ash composite.

8. The organic modifier according to claim 7, wherein, In step 1, the mass concentration of the chitosan dispersion is 1% to 1.5%; and / or In step 2, the particle size of the fly ash is 130 to 150 mesh; and / or In step 2, the microwave conditions are: power 500W to 800W, time 4min to 6min; and / or In step 3, the second silane coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane; and / or In step 3, the mass ratio of the modified fly ash to the second silane coupling agent is 100:(1 - 2); and / or In step 3, the heat preservation time is 60min to 70min; and / or In the chitosan-modified fly ash composite, the mass ratio of chitosan to modified fly ash is 1:(5 - 7).

9. The preparation method of the organic modifier according to any one of claims 1 to 8, characterized in that, It includes the following steps: Mix the weighed modified sludge, modified vermiculite, chitosan-modified fly ash composite material and decomposed wood chips evenly to obtain an organic improver.

10. Application of the organic improver described in any one of claims 1 to 8 or the organic improver prepared by the preparation method of the organic improver described in claim 9 in improving iron tailings sand soil.

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