Selenium-rich slow-release silicon fertilizer as well as preparation method and application thereof

Abstract

The invention provides a selenium-rich slow-release silicon fertilizer as well as a preparation method and application thereof, and relates to the technical field of soil remediation. Specifically, the method comprises the following steps: firstly, preparing a mixed solution containing coal gangue, selenite and slaked lime, and carrying out full dispersion, solid-liquid separation and drying to obtain a solid material; and then fully mixing the solid material with magnesium ore, and carrying out high-temperature roasting to obtain the selenium-rich slow-release silicon fertilizer. The invention provides a new way for resource utilization of coal gangue, the slow-release selenium-rich silicon fertilizer is prepared and obtained at the same time, the selenium fixation technology and the coal gangue passivation technology are innovatively adopted, the selenium-rich silicon fertilizer can effectively improve the yield and quality of crops, the heavy metal blocking effect of the crops is improved, and the selenium-rich silicon fertilizer is environmentally friendly; good application prospects are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of soil remediation, and in particular, to a selenium-rich slow-release silicon fertilizer, a preparation method thereof, and an application thereof. Background Art

[0002] As a solid waste inevitably generated during coal mining and processing, coal gangue has a complex composition, mainly including kaolinite, quartz, coal or organic matter, and other mineral impurities. These mountains of coal gangue not only occupy a large amount of land resources, but also, over time, its natural processes such as weathering and leaching, as well as possible spontaneous combustion phenomena, may trigger a series of environmental pollution problems, such as air pollution and ecological damage. In view of this, the resource utilization of coal gangue is particularly urgent and important. In recent years, the industry has been actively exploring how to turn coal gangue into treasure to realize its resource value.

[0003] In the practice of modern agricultural production, selenium fertilizer and silicon fertilizer have become indispensable trace element fertilizers, which play a crucial role in increasing crop yield and improving quality. Specifically, as an essential trace element in the life activities of plants and animals, the function of selenium is not only limited to meeting basic physiological needs, but more importantly, it can significantly enhance the stress resistance of crops, such as cold resistance, drought resistance, and disease resistance, thus ensuring the normal growth and development of crops under adverse conditions; at the same time, selenium can also improve the quality of agricultural products, such as increasing the protein content of food crops, enhancing the color and taste of fruits, etc., thereby enhancing the market value of agricultural products and the acceptance of consumers; in addition, selenium fertilizer can also reduce the heavy metal content of crops and reduce the risk of heavy metal migration by improving the soil environment, realizing the safe utilization of heavy metal-contaminated farmland. On the other hand, although silicon is not an essential element for plant growth, it plays an important role in plants. It can promote the photosynthesis of crops, improve the photosynthetic efficiency by enhancing the structure and function of chloroplasts, and thus promote the absorption and conversion of light energy by plants; at the same time, silicon can also significantly enhance the disease resistance and stress resistance of crops, such as resisting the invasion of fungal and bacterial diseases, reducing the use of pesticides, and reducing the pressure on the environment caused by agricultural production; moreover, the presence of silicon can also improve the stem strength of crops, prevent lodging, and improve the drought tolerance and salt tolerance of crops, which is of great significance for stabilizing agricultural production.

[0004] However, traditional fertilizers including selenium fertilizers and silicon fertilizers often have the problem of one-time release during application, which means that the nutrient elements in the fertilizers are released in large quantities in a short period of time, while crops cannot fully absorb and utilize these nutrients. This release pattern not only leads to the waste of nutrient elements, reduces the utilization rate of fertilizers, but also excessive nutrients will enter water bodies and soil through runoff, infiltration and other ways, causing environmental pollution and increasing the risks of water eutrophication and soil salinization. Therefore, how to improve the utilization efficiency of trace elements in fertilizers and reduce environmental pollution has become an urgent problem to be solved in the sustainable development of agriculture.

[0005] Slow-release fertilizers are an important solution to the above problems; through special coating technologies or chemical modification methods, slow-release fertilizers can control the release rate and duration of nutrients in fertilizers, making them match the growth needs of crops, so as to achieve the efficient utilization of nutrients and reduce environmental pollution. Especially in the application of selenium fertilizers and silicon fertilizers, slow-release technologies can ensure the stable supply of these two important trace elements during the crop growth cycle, maximizing their effects of promoting growth and improving quality.

[0006] In view of this, the present invention is specifically proposed. Summary of the Invention

[0007] The first object of the present invention is to provide a preparation method of selenium-rich slow-release silicon fertilizer, on the one hand, to provide a high-efficiency and high-value resource utilization channel for coal gangue, and on the other hand, to provide a selenium-silicon composite fertilizer with good slow-release effect and low cost.

[0008] The second object of the present invention is to provide a fertilizer with good selenium slow-release effect.

[0009] The third object of the present invention is to provide a resource treatment method for coal gangue to turn waste into treasure and realize the economic recycling of waste.

[0010] In order to achieve the above objects of the present invention, the following technical solutions are specifically adopted:

[0011] A preparation method of selenium-rich slow-release silicon fertilizer includes the following steps:

[0012] Prepare a mixed solution containing coal gangue, selenite and slaked lime, and obtain a solid material after sufficient dispersion, solid-liquid separation and drying;

[0013] Fully mix the solid material with magnesite ore, and then conduct high-temperature roasting to obtain selenium-rich slow-release silicon fertilizer.

[0014] A fertilizer includes the selenium-rich slow-release silicon fertilizer prepared by the preparation method of the selenium-rich slow-release silicon fertilizer.

[0015] A resource utilization method for coal gangue, including the preparation method of the selenium-rich slow-release silicon fertilizer described above.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] (1) The present invention provides a method for preparing selenium-rich slow-release silicon fertilizer using coal gangue. This method realizes the resource utilization of coal gangue. By efficiently using this silicate coal gangue as a raw material, it provides a new way for the treatment of solid waste, increases its economic value, and conforms to the concepts of circular economy and sustainable development.

[0018] (2) The selenium-rich silicon fertilizer with a slow-release effect prepared by the present invention has controllable slow-release performance. At the same time, by adjusting the types of raw materials of magnesite, the addition amount, and the calcination conditions, it can meet the growth requirements of different target crops, which helps to improve the stress resistance, yield, and quality of crops, and has a positive impact on agricultural production.

[0019] (3) The selenium-rich slow-release silicon fertilizer of the present invention or a fertilizer product containing the selenium-rich slow-release silicon fertilizer realizes the stepwise dissolution of selenium and silicon by adopting innovative selenium fixation technology and coal gangue passivation technology. Specifically, the present invention promotes the formation of selenate (SeO4 2- ) through the alkalinity of slaked lime. Its solubility is lower than that of selenite, reducing the mobility of selenium. Further, during high-temperature calcination, after the coal gangue and magnesite are mixed, silicate mineral reconstruction occurs. Selenium replaces sulfur or oxygen in the silicate lattice in the form of isomorphous substitution to form a selenium silicate complex (such as CaSeO3·SiO2), thereby achieving long-term slow release. At the same time, after the coal gangue and slaked lime are mixed, the slaked lime provides alkalinity. When subsequently mixed and calcined with magnesite, the hydroxide of magnesium and the silicate mineral form a stable vitreous structure under high-temperature conditions, which also improves the slow-release property. In addition, the importance of this stepwise release mechanism is that it can ensure the slow and continuous release of selenium and silicon elements during the growth process of crops, thereby improving the absorption efficiency of these two elements by crops and reducing the loss of elements and environmental pollution. Detailed implementation manners

[0020] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but those skilled in the art will appreciate that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Those who do not specify the manufacturer for reagents or instruments used are conventional products that can be purchased commercially. In addition, the terms "first", "second" and "third" are only used for descriptive purposes and cannot be interpreted as indicating or implying relative importance.

[0021] The first aspect of the present invention is to provide a method for preparing a selenium-rich slow-release silicon fertilizer, which mainly includes the following steps: first preparing a mixed solution containing coal gangue, selenite and slaked lime, and obtaining a solid material after sufficient dispersion, solid-liquid separation, and drying; fully mixing the solid material with magnesium ore, and then high-temperature roasting to obtain the selenium-rich slow-release silicon fertilizer of the present invention.

[0022] As a preferred embodiment, the preparation method includes: pretreatment of the gangue, and the pretreatment includes crushing, screening and washing to remove impurities in the gangue raw materials and obtain low-particle-size gangue fine powder to achieve good dispersion of the gangue in the subsequent mixed slurry. In some feasible embodiments in the field, the crushing includes but is not limited to one or more of crushing, splitting, grinding, impact, etc., and in actual application, crushing equipment is selected according to several of the above crushing processes for joint use.

[0023] As a preferred embodiment, the particle size of the coal gangue is ≤0.1 mm; in some more preferred embodiments, the particle size of the coal gangue is 0.01 mm to 0.1 mm.

[0024] As a preferred embodiment, the selenite includes at least one of sodium selenite or potassium selenite.

[0025] As a preferred embodiment, the concentration of selenite in the mixed solution is 0.1 mol / L to 1.0 mol / L, including but not limited to any one of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 (mol / L) or a numerical range consisting of any two of them.

[0026] As a preferred embodiment, the preparation of the mixed solution includes: first preparing a solution of the selenite, adjusting the pH of the solution to 7-9, and then sequentially adding the coal gangue and the slaked lime; wherein, the pH adjuster includes but is not limited to sodium hydroxide, potassium hydroxide, dilute hydrochloric acid, dilute sulfuric acid or dilute nitric acid, etc., mainly by adding a certain amount of alkali adjuster to promote the full dissolution of the selenite.

[0027] As a preferred embodiment, the preparation of the mixed solution includes: first preparing a solution of the selenite, adding the coal gangue after sufficient dispersion, adding the slaked lime after sufficient dispersion again, and obtaining the mixed solution after sufficient dispersion; for any of the above-mentioned "sufficient dispersion", methods such as oscillation, stirring, shaker, centrifugation, ultrasound, heating, etc. can be selected to assist, which helps to accelerate dispersion and obtain a relatively uniform dispersion system.

[0028] As a preferred embodiment, the addition amount of the slaked lime is measured based on the addition amount of the coal gangue. Specifically, the mass ratio of the slaked lime to the coal gangue is 0.1-0.3, including but not limited to any one or any numerical range composed of any two of 0.1, 0.12, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3.

[0029] As a preferred embodiment, the solid-liquid separation includes but is not limited to decantation, filtration, centrifugal separation, filter screen or membrane separation, etc.; in a more preferred embodiment, the solid-liquid separation in this step is carried out by suction filtration in a low-production mode or a laboratory scenario, while in a large-scale batch production mode, the solid-liquid separation can be carried out by a combination of filter screen or suction filtration.

[0030] As a preferred embodiment, the drying is carried out by hot air drying; the drying temperature is controlled at 50°C-100°C, and the drying time is 20h-60h.

[0031] As a preferred embodiment, the magnesium ore includes but is not limited to at least one of magnesite, dolomite, kieserite, carnallite, kainite, black talc or struvite; in some more preferred embodiments, the magnesium ore uses dolomite, black talc or struvite, or is comprehensively selected based on the production region, ore cost or transportation cost.

[0032] As a preferred embodiment, the addition amount of the magnesium ore is measured based on the addition amount of the coal gangue. Specifically, the mass ratio of the magnesium ore to the coal gangue is 0.1 to 0.3, including but not limited to any one or any numerical range composed of any two of 0.1, 0.12, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3.

[0033] As a preferred embodiment, the roasting temperature is 500°C to 1200°C, and the roasting time is 0.5 h to 4 h; in some alternative embodiments, the roasting temperature includes but not limited to any one or any numerical range composed of any two of 500, 600, 700, 800, 900, 1000, 1100, 1200 (°C), and the roasting time includes but not limited to any one or any numerical range composed of any two of 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4 (h). It can be understood that based on the roasting time and temperature provided by the present invention, it should be adaptively adjusted according to the material characteristics of the selected magnesium ore and the difference of the roasting equipment.

[0034] As a preferred embodiment, the heating rate of the roasting is 1°C / min to 10°C / min, and more preferably 2°C / min is adopted; in the present invention, it is preferably to gradually heat up in a programmed manner until the set roasting temperature is reached to avoid the material from cracking due to excessive temperature difference.

[0035] As a preferred embodiment, after the roasting, it further includes: cooling, screening, and packaging to ensure the stability of the product and facilitate storage and transportation; in some more preferred embodiments, the products that do not meet the particle size requirements during screening are subjected to additional crushing treatment; in the present invention, the particle size of the selenium-rich slow-release silicon fertilizer is 0.05 mm to 0.5 mm, and more preferably 0.1 mm ± 0.05 mm.

[0036] The second aspect of the present invention lies in providing a fertilizer, including a silicon fertilizer prepared based on the preparation method of the selenium-rich slow-release silicon fertilizer as described in the first aspect. It can be understood that the fertilizer in the present invention can be composed only of the selenium-rich slow-release silicon fertilizer, thereby obtaining a specific trace fertilizer product, or it can also include other fertilizer components of macronutrients or micronutrients and obtain a compound fertilizer product; those skilled in the art can make any adjustments based on their market demand or farming requirements, and any functional product with the function of fertilizer under the premise of including the selenium-rich slow-release silicon fertilizer belongs to an embodiment of this aspect.

[0037] The third aspect of the present invention lies in providing a method for resource treatment of coal gangue, including the preparation method of selenium-rich slow-release silicon fertilizer as described in the first aspect. It can be understood that the resource treatment method described in the present invention may also include other treatment processes or procedures, that is, other operation steps may be introduced into the preparation method of the selenium-rich slow-release silicon fertilizer, or process expansion may be carried out based on the preparation method of the selenium-rich slow-release silicon fertilizer; on the premise of including the preparation method of the selenium-rich slow-release silicon fertilizer, any technological process based on coal gangue can belong to an implementation manner of this aspect.

[0038] Example 1

[0039] Prepare the following raw materials: 100 g of coal gangue, 1 g of sodium selenite, 15 g of slaked lime, and 10 g of dolomite. Dissolve 1 g of sodium selenite in deionized water to obtain an aqueous solution with a concentration of 0.5 mol / L. Then, add 100 g of crushed and screened coal gangue (particle size: 0.08 mm ± 0.01 mm) to the sodium selenite solution and stir well to form a slurry. Next, add 15 g of slaked lime to the slurry and continue to stir evenly. After that, separate by pressure filtration to obtain solid materials, and dry them in hot air at 60 °C for 30 hours. Mix the dried solid materials with 10 g of dolomite and stir evenly again. Subsequently, calcine the mixed materials at 700 °C for 2 hours. Finally, after cooling, screening, and packaging, the slow-release selenium-rich silicon fertilizer of this example is finally obtained.

[0040] Example 2

[0041] Prepare the following raw materials: 100 g of coal gangue, 0.5 g of sodium selenite, 10 g of slaked lime, and 20 g of dolomite. Dissolve 0.5 g of sodium selenite in deionized water to obtain an aqueous solution with a concentration of 0.5 mol / L. Then, add 100 g of crushed and screened coal gangue (particle size: 0.08 mm ± 0.01 mm) to the sodium selenite solution and stir well to form a slurry. Next, add 10 g of slaked lime to the slurry and continue to stir evenly. After that, separate by pressure filtration to obtain solid materials, and dry them in hot air at 80 °C for 40 hours. Mix the dried solid materials with 20 g of dolomite and stir evenly again. Subsequently, calcine the mixed materials at 1000 °C for 1 hour. Finally, after cooling, screening, and packaging, the slow-release selenium-rich silicon fertilizer of this example is finally obtained.

[0042] Example 3

[0043] Prepare the following raw materials: 100 g of coal gangue, 1.5 g of sodium selenite, 20 g of slaked lime, and 5 g of black talc. Dissolve 1.5 g of sodium selenite in deionized water to obtain an aqueous solution with a concentration of 0.5 mol / L. Next, add 100 g of crushed and screened coal gangue (particle size: 0.08 mm ± 0.01 mm) to the sodium selenite solution and stir well to form a slurry. Then, add 20 g of slaked lime to the slurry and continue to stir evenly. After that, perform pressure filtration separation to obtain solid materials, and dry them in hot air at 70 °C for 20 hours. Mix the dried solid materials with 5 g of black talc and stir evenly again. Subsequently, calcine the mixed materials at 500 °C for 0.5 hour. Finally, after cooling, screening, and packaging, the slow-release selenium-rich silicon fertilizer of this example is finally obtained.

[0044] Example 4

[0045] Prepare the following raw materials: 100 g of coal gangue, 0.8 g of sodium selenite, 12 g of slaked lime, and 15 g of black talc. Dissolve 0.8 g of sodium selenite in deionized water to obtain an aqueous solution with a concentration of 0.5 mol / L. Next, add 100 g of crushed and screened coal gangue (particle size: 0.08 mm ± 0.01 mm) to the sodium selenite solution and stir well to form a slurry. Then, add 12 g of slaked lime to the slurry and continue to stir evenly. After that, perform pressure filtration separation to obtain solid materials, and dry them in hot air at 90 °C for 10 hours. Mix the dried solid materials with 15 g of black talc and stir evenly again. Subsequently, calcine the mixed materials at 900 °C for 2 hours. Finally, after cooling, screening, and packaging, the slow-release selenium-rich silicon fertilizer of this example is finally obtained.

[0046] Example 5

[0047] Prepare the following raw materials: 100 g of coal gangue, 1.2 g of sodium selenite, 18 g of slaked lime, and 8 g of struvite. Dissolve 1.2 g of sodium selenite in deionized water to obtain an aqueous solution with a concentration of 0.5 mol / L. Next, add 100 g of crushed and screened coal gangue (particle size: 0.08 mm ± 0.01 mm) to the sodium selenite solution and stir well to form a slurry. Then, add 18 g of slaked lime to the slurry and continue to stir evenly. After that, perform pressure filtration separation to obtain solid materials, and dry them in hot air at 60 °C for 30 hours. Mix the dried solid materials with 8 g of struvite and stir evenly again. Subsequently, calcine the mixed materials at 1000 °C for 0.5 hour. Finally, after cooling, screening, and packaging, the slow-release selenium-rich silicon fertilizer of this example is finally obtained.

[0048] Comparative Example

[0049] Dissolve 5 g of sodium selenite in deionized water to obtain a 1 mol / L aqueous solution. Then, add 100 g of crushed and screened coal gangue (particle size: 0.08 mm ± 0.01 mm) to the sodium selenite solution and stir well to form a soil conditioner.

[0050] Test Example

[0051] Weigh 5 g of the slow-release selenium-rich silicon fertilizer prepared in each of the above examples and the soil conditioner in the comparative example as samples, and independently add them to 50 mL of a mixed solution of 0.025 mol / L citric acid and 0.1 mol / L dipotassium hydrogen phosphate, and place them in a constant temperature oscillator and shake for 24 hours at 30 °C to ensure that the silicon and selenium in the samples are fully dissolved into the leaching solution. After shaking for 6 hours, 12 hours, 18 hours, and after the shaking is completed, sample and filter the leaching solution respectively to obtain a clear filtrate. Then, independently use an inductively coupled plasma emission spectrometer to measure the silicon and selenium contents in the clear solution, and calculate the contents of available silicon and selenium in the samples through a standard curve, and record them as shown in Table 1 below.

[0052] Table 1

[0053]

[0054]

[0055] As can be seen from Table 1, the slow-release selenium-rich silicon fertilizer of the present invention has the effect of long-term slow release over time, and has a good effect of supplementing selenium and silicon, and has an excellent effect on improving the stress resistance, yield and quality of crops.

[0056] Although the present invention has been illustrated and described with specific examples, it should be realized that the above examples are only used to illustrate the technical solutions of the present invention and are not intended to limit it; those of ordinary skill in the art should understand that without departing from the spirit and scope of the present invention, the technical solutions described in the foregoing examples can be modified, or some or all of the technical features can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such replacements and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A preparation method of selenium-rich slow-release silicon fertilizer, characterized in that, It includes the following steps: Prepare a mixed solution containing coal gangue, selenite and slaked lime, and obtain a solid material after sufficient dispersion, solid-liquid separation and drying; Fully mix the solid material with magnesite ore, and then carry out roasting to obtain selenium-rich slow-release silicon fertilizer; The temperature of the roasting is 500°C to 1200°C, and the time of the roasting is 0.5 h to 4 h.

2. The preparation method of the selenium-rich slow-release silicon fertilizer according to claim 1, characterized in that, Before the preparation method, it also includes the pretreatment of the coal gangue; The pretreatment includes crushing, screening and cleaning to obtain the coal gangue with a particle size ≤ 0.1 mm.

3. The preparation method of the selenium-rich slow-release silicon fertilizer according to claim 1, characterized in that The selenite includes at least one of sodium selenite or potassium selenite; And / or, the concentration of the selenite in the mixed solution is 0.1 mol / L to 1.0 mol / L.

4. The preparation method of the selenium-rich slow-release silicon fertilizer according to claim 1, characterized in that, The preparation of the mixed solution includes: first prepare a solution of the selenite, adjust the pH of the solution to 7 to 9, and then sequentially add the coal gangue and the slaked lime.

5. The preparation method of the selenium-rich slow-release silicon fertilizer according to claim 1, characterized in that, The mass ratio of the slaked lime to the coal gangue is 0.1 to 0.

3.

6. The preparation method of the selenium-rich slow-release silicon fertilizer according to claim 1, characterized in that, The magnesite ore includes at least one of magnesite, dolomite, hydromagnesite, bischofite, carnallite, black talc or struvite; And / or, the mass ratio of the magnesite ore to the coal gangue is 0.1 to 0.

3.

7. The preparation method of the selenium-rich slow-release silicon fertilizer according to claim 1, characterized in that, The temperature of the drying is 50°C to 100°C, and the time of the drying is 20 h to 60 h.

8. A fertilizer, characterized in that, It includes the selenium-rich slow-release silicon fertilizer prepared by the preparation method of the selenium-rich slow-release silicon fertilizer according to any one of claims 1 to 7.

9. A resource treatment method for coal gangue, characterized in that, It includes the preparation method of the selenium-rich slow-release silicon fertilizer according to any one of claims 1 to 7.

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