A method for producing an organic soil amendment granule

Abstract

The application discloses a kind of organic soil remediation agent granules production method, including the following preparation steps: functional compatibility ingredient, raw material is selected according to mass percentage, with natural mineral clay as carrier, add organic matter component, particle reinforcing agent and functional additive;Dry mixing grinding, natural mineral clay is sent into grinder and grinds, then with humic acid powder is together put into mixing machine, after dry mixing stirring, obtain uniform mixture material;Disc granulation;Post-treatment solidification.The application is by with natural mineral clay rich in silicon, titanium, rare earth and multiple trace elements as unified carrier, simultaneously realizes passivation heavy metal, increases soil organic matter, improves soil structure and the like multiple functions, overcomes the defects of single function of existing product, by the synergistic effect of design organic matter, inorganic clay and particle reinforcing agent, realizes the unity of particle strength, porosity and organic matter availability.

Description

Technical Field

[0001] This invention relates to the field of soil remediation and improvement technology, and in particular to a method for preparing organic soil remediation agent granules. Background Technology

[0002] The complex degradation problems of soil, such as excessive heavy metals, secondary salinization, soil compaction, and lack of organic matter, have become a major bottleneck restricting the sustainable development of modern agriculture, requiring organic soil remediation granules to repair the soil.

[0003] Current soil remediation agents often suffer from single-function limitations, such as merely passivating metals or supplementing organic matter. They lack synergistic remediation capabilities, are unable to address complex soil pollution, or provide the trace elements necessary for plant growth. Furthermore, their complex manufacturing processes and high costs may introduce secondary pollution risks, making them unsuitable for large-scale agricultural applications. Moreover, existing soil remediation technologies do not consider soil as a complex system, resulting in limited functionality and an inability to address complex pollution such as soil compaction and heavy metal contamination. Some technologies employ harsh conditions such as high temperatures and strong acids / alkalis to ensure performance, leading to high energy consumption and potential secondary pollution, which contradicts the principles of green sustainability.

[0004] A method for producing a bio-modified clay mineral replanting soil remediation agent and a product are disclosed in Chinese patent document with announcement number [number missing]. The method and product for producing the bio-modified clay mineral replanting soil remediation agent use elemental minerals and clay minerals as a matrix. After bio-modification, chitin and soil conditioning bacteria are loaded onto the matrix. The product is then granulated and coated with clay minerals in a secondary manner. The resulting product can remediate the nutrient components, soil microecology, and soil enzyme system of continuously cropped soils. Applying the bio-modified clay mineral soil remediation agent can increase the content of soil organic matter, available nitrogen, available phosphorus, and available potassium by 5.84 g / kg, 38.55 g / kg, 31.01 mg / kg, and 66.33 mg / kg, respectively; and increase the content of urease, catalase, sucrase, and phosphatase in the soil by 1.89 times, 1.58 times, 1.80 times, and 2.51 times, respectively. However, the production method and product of this bio-modified clay mineral soil remediation agent only focus on continuously cropped soils and only solve problems such as nutrient imbalance, low soil enzyme activity, root rot, and microbial community imbalance; it has no ability to passivate heavy metals or improve saline-alkali land and cannot cope with complex soil pollution.

[0005] A heavy metal soil remediation agent and its preparation and application methods are disclosed in Chinese patent document CN108277013B. This heavy metal soil remediation agent and its preparation and application methods include polyacrylamide, zeolite, distilled water, calcium cellulose sulfonate, modified apatite, molasses, biochar, phosphate compounds, and a compound microbial agent. The phosphate compounds, molasses, and biochar are mixed evenly, then the compound microbial agent is added and fermented. Polyacrylamide, zeolite, calcium cellulose sulfonate, modified apatite, and distilled water are added to the resulting mixture, mixed evenly, dried, and then pulverized to obtain the heavy metal soil remediation agent. This heavy metal soil remediation agent is highly efficient with small dosage and short remediation cycle. It can not only reduce the heavy metal content in the soil and effectively control soil pollution, but also improve soil fertility and restore soil arability as soon as possible while restoring the soil ecosystem. However, this heavy metal soil remediation agent and its preparation and application methods only focus on the passivation and fixation of heavy metals such as copper, cadmium, lead, zinc and arsenic. It does not have the functions of improving soil compaction, regulating salinity and alkalinity, supplementing crop trace elements and long-term fertilization. Its functions are limited.

[0006] A heavy metal contaminated soil remediation agent, its preparation method, and its application method are disclosed in Chinese patent document CN111100652A. This heavy metal contaminated soil remediation agent and its preparation and application methods include a fixative component and a conditioning component in a mass ratio of 1:2-3. The fixative component includes the following components in parts by weight: 15-35 parts modified nano-hydroxyapatite, 12.5-28.5 parts sulfuric acid modified bentonite, 5-9 parts zeolite, 3-7 parts limestone, 6-10 parts tartaric acid, 6-10 parts activated steel slag, and 1-3 parts chelating agent. The conditioning component includes the following components in parts by weight: 15-35 parts modified maifanite, 12-20 parts modified straw, 5.8-9 parts nano-iron powder, 3-11 parts sodium humate, 4-12 parts fly ash, 5.6-7.2 parts carboxymethyl cellulose, and 10-14 parts biochar. The heavy metal contaminated soil remediation agent of the present invention has the advantages of good removal and remediation effects on divalent heavy metal ions such as copper, zinc, chromium and nickel. However, the heavy metal contaminated soil remediation agent, its preparation method and application method are divided into two independent components: fixative and conditioning agent. They need to be prepared separately and constructed in steps (first solidification and curing, then rinsing, and finally conditioning), which is lengthy and cumbersome.

[0007] To address the shortcomings of the existing technologies, providing a method for preparing organic soil remediation agent granules is a worthwhile research topic. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of dealing with complex pollution such as soil compaction and heavy metal contamination, and to provide a method for manufacturing organic soil remediation agent particles, which achieves technical effects suitable for the remediation of soils with complex pollution.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] A method for preparing organic soil remediation agent granules includes the following preparation steps:

[0011] Step 1: Functional formulation and ingredient selection. Raw materials are selected according to mass percentage, with natural mineral clay as the carrier, and organic components, particle reinforcing agents, and functional additives are added.

[0012] Step 2: Dry mixing and grinding. The natural mineral clay is fed into the mill for grinding, and then put into the mixer together with the humic acid powder. After dry mixing, a uniform mixture is obtained.

[0013] Step 3: Disc granulation. The mixed materials are conveyed into the inclined disc granulator, where atomized water is sprayed to cause the materials to agglomerate and form spherical wet granules with a particle size of 2-6mm under the action of the rotating disc.

[0014] Step 4: Post-treatment and curing. The granulated wet granules are fed into a drum dryer at a temperature of 80-110℃ and dried until the moisture content is ≤5%. After cooling to room temperature, qualified granules of 3-5 mm are taken by vibrating screen. The yield rate is ≥90%, the compressive strength of the granules is ≥15 N / granule, the disintegration time in water is ≤30 min, and the porosity is 25-40%. Organic soil remediation agent granules are thus obtained.

[0015] Optionally, the natural mineral clay in step one is rich in silicon, titanium, and rare earth elements, and also contains trace elements iron, zinc, boron, and molybdenum, with the natural mineral clay comprising 60-75% by mass.

[0016] Before mixing, the natural mineral clay is dried at 105℃±5℃ to a moisture content of <12%, and then pulverized in a Raymond mill to 60-100 mesh with a sieve pass rate of ≥95%. This achieves the goal of constructing a multifunctional carrier based on the mineral clay, while simultaneously satisfying the functions of soil remediation, structural improvement, and trace element supply.

[0017] Optionally, the organic matter component in step one has a mass ratio of 15-30%, the organic matter component has a humic acid content of ≥50%, and the organic matter component is processed to 80-120 mesh before mixing, so as to replenish the soil with organic matter, provide active functional groups, assist in the passivation of heavy metals, and improve soil fertility in a long-term manner.

[0018] Optionally, the mass ratio of the particle reinforcing agent in step one is 5-10%, and the particle reinforcing agent includes inorganic reinforcing agents and organic polymer binders;

[0019] The inorganic reinforcing agent is magnesium sulfate, and its dosage accounts for 6-10% of the total dry basis.

[0020] The organic polymer binder is polyacrylamide (PAM, Mw 6-8 million) or sodium carboxymethyl cellulose (CMC), accounting for 1-2% of the total dry basis. When used, it is prepared as a 1-2% aqueous solution to achieve the effects of stabilizing the three-dimensional structure of the particles, extending the field action period of the product, and adapting to mechanized application operations.

[0021] Optionally, the mass ratio of the functional additive in step one is 0.5-1.0%, and the functional additive is a soil aggregation promoter. The soil aggregation promoter uses polyglutamic acid to repair the soil physical structure, optimize the water and fertilizer conduction environment, and synergistically improve the comprehensive efficacy of repair and improvement.

[0022] Optionally, the mass ratio of the functional additive in step one is 0.5-1.0%, and the functional additive is a trace element supplement. The trace element supplement can supplement the essential trace nutrients for crop growth and complement the inherent elements of mineral clay to achieve comprehensive nutrition.

[0023] Optionally, the mixer in step two is a double-helix mixer. The double-helix mixer mixes mineral clay powder, inorganic reinforcing agent and humic acid powder at 25-35 r / min for 10-15 min until the coefficient of variation of mixing uniformity CV ≤ 5%. Then, the spray device is turned on and liquid organic polymer binder is added. The overall moisture content is controlled at 12-20% to avoid component segregation and improve the consistency of pellet formation and the stability of particle quality.

[0024] Optionally, in step three, the diameter of the inclined disc granulator is 2-3m, the inclination angle is 45-55°, the rotation speed is 20-30r / min, and the atomizing nozzle sprays atomized water or dilute binder solution at a pressure of 0.2-0.4MPa with a spray volume of 2-5L / min.

[0025] After granulation for 30-60 minutes, 2-6 mm spherical particles are formed, with a sphericity rate of ≥85%, ensuring uniform particle size, even application, and stable and controllable repair effect.

[0026] Optionally, during the post-treatment curing in step four, low-temperature calcination is performed at 200–300°C for 1–2 hours to improve particle strength and pore stability.

[0027] Positive and beneficial effects: 1. The production method of this organic soil remediation agent granules uses natural mineral clay rich in silicon, titanium, rare earth and various trace elements as a unified carrier to simultaneously achieve multiple functions such as passivation of heavy metals, increase of soil organic matter and improvement of soil structure. This overcomes the shortcomings of existing products with single functions. By designing the synergistic effect of organic matter (providing carbon source and functional groups), inorganic clay (providing skeleton and adsorption) and particle enhancer (providing bonding and strength), the unity of particle strength, porosity and organic matter availability is achieved.

[0028] 2. The production method of this organic soil remediation agent granules allows the product to not only remediate pollution, but also improve soil fertility by improving soil aggregate structure and increasing organic matter content, and supplement silicon, titanium, rare earth and trace elements to promote crop growth, thus achieving the sustainable goal of "remediation and fertilization at the same time".

[0029] 3. The production method of this organic soil remediation agent granules mainly uses natural minerals and organic matter. The process is mild, energy-efficient, and more in line with the requirements of green and low-carbon development. Attached Figure Description

[0030] Figure 1 Here is an example of a SEM image of the repair agent particles of the present invention;

[0031] Figure 2 This is a bar chart comparing the Cd bioavailability content in Example 2 of the present invention;

[0032] Figure 3 This is a bar chart comparing the content of active As in Example 2 of the present invention;

[0033] Figure 4 This is a diagram showing the changes in soil aggregates and organic matter in Example 2 of the present invention;

[0034] Figure 5 This is a graph showing the relationship between corn growth and Cd accumulation in kernels in Example 2 of the present invention. Detailed Implementation

[0035] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0036] Example 1

[0037] A method for preparing organic soil remediation agent granules includes the following preparation steps:

[0038] Step 1: Functional formulation and ingredient selection. Raw materials are selected according to mass percentage, with natural mineral clay as the carrier, and organic components, particle reinforcing agents, and functional additives are added.

[0039] Step 2: Dry mixing and grinding. The natural mineral clay is fed into the mill for grinding, and then put into the mixer together with the humic acid powder. After dry mixing, a uniform mixture is obtained.

[0040] Step 3: Disc granulation. The mixed materials are conveyed into the inclined disc granulator, where atomized water is sprayed to cause the materials to agglomerate and form spherical wet granules with a particle size of 2-6mm under the action of the rotating disc.

[0041] Step 4: Post-treatment and curing. The granulated wet granules are fed into a drum dryer at 80–110℃ until the moisture content is ≤5%. After cooling to room temperature, qualified granules of 3–5 mm are collected via a vibrating screen. The yield rate is ≥90%, the compressive strength of the granules is ≥15 N / granule, the disintegration time in water is ≤30 min, and the porosity is 25–40%. This yields the organic soil remediation agent granules. SEM images of the remediation agent granules are shown below. Figure 1 As shown.

[0042] The natural mineral clay in step one is rich in silicon, titanium, and rare earth elements, and also contains trace elements such as iron, zinc, boron, and molybdenum. The mass ratio of natural mineral clay is 60-75%.

[0043] Before mixing, the natural mineral clay is dried at 105℃±5℃ to a moisture content of <12%, and then pulverized in a Raymond mill to 60-100 mesh with a sieve pass rate of ≥95%. The physical and chemical state and particle size uniformity of the carrier raw materials are strictly controlled to ensure stable moisture content, consistent powder fineness, and good mixing and dispersibility. This achieves the goal of constructing a multifunctional carrier based on mineral clay, while simultaneously meeting the needs of soil remediation, structural improvement, and trace element supply.

[0044] The organic matter component in step one has a mass ratio of 15-30%, and the humic acid content in the organic matter component is ≥50%. Before mixing, the organic matter component is processed by a pulverizer to 80-120 mesh to ensure the purity of the organic matter and the dispersion performance of the powder, effectively avoid the agglomeration of organic matter and uneven mixing of materials, replenish the soil with organic matter, provide active functional groups, assist in the passivation of heavy metals, and improve soil fertility in a long-term manner.

[0045] In step one, the mass ratio of the particle reinforcing agent is 5-10%, and the particle reinforcing agent includes inorganic reinforcing agents and organic polymer binders;

[0046] The inorganic reinforcing agent is magnesium sulfate, which accounts for 6-10% of the total dry basis.

[0047] The organic polymer binder is polyacrylamide (PAM, Mw 6-8 million) or sodium carboxymethyl cellulose (CMC), accounting for 1-2% of the total dry basis. When used, it is prepared as a 1-2% aqueous solution to construct an organic-inorganic composite bonding and reinforcing system. The resulting particles have high forming strength, are not easily disintegrated, and have a suitable pore structure, thus achieving the effects of stabilizing the three-dimensional structure of the particles, extending the field action period of the product, and being suitable for mechanized application operations.

[0048] The functional additive in step one has a mass ratio of 0.5% to 1.0%. The functional additive is a soil aggregation promoter, which uses polyglutamic acid. This soil aggregation promoter is introduced in a targeted manner to improve soil structure, rapidly promote the formation of soil aggregates, break up soil compaction and salinization, repair soil physical structure, optimize water and fertilizer conduction environment, and synergistically enhance the comprehensive effectiveness of soil remediation and improvement.

[0049] The functional additive in step one has a mass ratio of 0.5% to 1.0%. The functional additive is a micronutrient supplement, which can supplement the micronutrients necessary for crop growth and complement the inherent elements of mineral clay to achieve comprehensive nutrition.

[0050] The mixer used in step two is a double-helix mixer. The double-helix mixer mixes mineral clay powder, inorganic reinforcing agent and humic acid powder at 25-35 r / min for 10-15 min until the coefficient of variation (CV) of the mixing uniformity is ≤5%. Then the spray device is turned on and liquid organic polymer binder is added. Mixing continues until the material reaches the state of "forming a clump when squeezed by hand, but crumbling when touched". The overall moisture content is controlled at 12-20% (adjusted slightly according to the water absorption rate of the clay). The solid and liquid components are mixed in stages to ensure that the raw material components are mixed evenly and the dry and wet state of the material is suitable for granulation requirements, avoiding component segregation and improving the consistency of pellet formation and the stability of particle quality.

[0051] In step three, the diameter of the inclined disc granulator is 2-3m, the inclination angle is 45-55°, the rotation speed is 20-30r / min, and the atomizing nozzle sprays atomized water or dilute binder solution at a pressure of 0.2-0.4MPa with a spray volume of 2-5L / min.

[0052] After granulation for 30-60 minutes, spherical particles of 2-6 mm are formed, with a sphericity rate of ≥85%. By using technical means to limit the structural parameters, operating parameters, spray pressure and flow rate, granulation time and sphericity rate of the disc granulator, the rolling agglomeration and forming process is precisely controlled. This achieves the effects of high sphericity rate, good particle sphericity and uniform particle size distribution, ensuring that the finished particles have uniform specifications, uniform application and stable and controllable repair effect.

[0053] In step four, the post-treatment curing involves low-temperature calcination at 200–300°C for 1–2 hours to improve particle strength and pore stability.

[0054] Example 2

[0055] General-purpose composite pollution remediation particles

[0056] 1. The formula is shown in the table below (mass percentage).

[0057]

[0058] 2. Preparation steps

[0059] a. Dry and pulverize the mineral clay to 80 mesh, and pulverize the humic acid to 100 mesh;

[0060] b. Dry mix for 12 min, then spray with CMC solution and mix until the water content is 12%;

[0061] c. Disc granulation (inclination angle 50°, rotation speed 25 r / min, duration 45 min) to obtain 2-6 mm wet particles;

[0062] d. Dry at 100℃ until the moisture content is ≤5%, and sieve to obtain 3-5 mm granules.

[0063] 3. Performance and application verification (simulated potted plant, 30 days)

[0064] Test soil: Cd 1.8 mg / kg, Pb 210 mg / kg, PAHs 15 mg / kg, pH 8.1. CK (no additives), T1 (2% of this granule), and T2 (2% commercially available lime + biochar agent) were defined.

[0065]

[0066] Note: T1 values ​​differed significantly from CK values ​​(p<0.05), such as... Figures 2-5 As shown, it is superior to T2.

[0067] Example 3

[0068] Saline-alkali land improvement granules

[0069] The formula is shown in the table below (by weight).

[0070]

[0071] The process is the same as in Example 2, with granulation water content of 18% and pH of 7.8–8.2. Pot experiments in saline-alkali soil showed that soil electrical conductivity decreased by 35%, alkalinity decreased by 28%, and sunflower germination rate increased by 40%.

[0072] Example 4

[0073] When this soil remediation agent was applied to a saline-alkali farmland contaminated with heavy metals, after 3 months of remediation, the content of heavy metals cadmium and lead in the soil decreased by 50% and 40% respectively, the soil pH value dropped from 9.2 to 8.1, and the yield of corn crops increased by 20%.

[0074] The working principle of this invention is as follows:

[0075] S1 uses natural mineral clay rich in silicon, titanium, rare earth and various trace elements as the core carrier, compounded with humic organic matter, inorganic-organic composite particle enhancer, polyglutamic acid soil aggregation promoter and trace element supplement. Through precise functional compatibility, raw material drying and ultra-fine grinding, double spiral classification and uniform mixing, inclined disc atomization rolling granulation, medium temperature drying, cooling and screening closed-loop process, a three-dimensional composite structure of organic-inorganic-enhancing agent is constructed.

[0076] S2 abandons the harsh preparation conditions of traditional high temperature, strong acid and strong alkali, and relies on the synergistic function of each component to integrate heavy metal passivation, saline-alkali land improvement, soil compaction removal, organic matter enhancement, and slow-release replenishment of silicon, titanium, rare earth and trace elements. It realizes the simultaneous completion of soil remediation, improvement and fertilization. The process is green and low-carbon, with no secondary pollution, and the materials can be recycled. It is suitable for large-scale promotion and application in farmland with compound pollution and saline-alkali land.

[0077] The above is only used to illustrate the technical solution of the present invention and not to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing organic soil remediation agent granules, characterized in that, The preparation steps include the following: Step 1: Functional formulation and ingredient selection. Raw materials are selected according to mass percentage, with natural mineral clay as the carrier, and organic components, particle reinforcing agents, and functional additives are added. Step 2: Dry mixing and grinding. The natural mineral clay is fed into the mill for grinding, and then put into the mixer together with the humic acid powder. After dry mixing, a uniform mixture is obtained. Step 3: Disc granulation. The mixed materials are conveyed into the inclined disc granulator, where atomized water is sprayed to cause the materials to agglomerate and form spherical wet granules with a particle size of 2-6mm under the action of the rotating disc. Step 4: Post-treatment and curing. The granulated wet granules are sent to a drum dryer at a temperature of 80-110℃ and dried until the moisture content is ≤5%. After cooling to room temperature, qualified granules of 3-5 mm are taken through a vibrating screen. The compressive strength of the granules is ≥15 N / granule, the disintegration time in water is ≤30 min, and the porosity is 25-40%. The organic soil remediation agent granules are then obtained.

2. The method for preparing organic soil remediation agent granules according to claim 1, characterized in that: The natural mineral clay in step one is rich in silicon, titanium, and rare earth elements, and also contains trace elements such as iron, zinc, boron, and molybdenum. The mass ratio of the natural mineral clay is 60-75%. Before mixing, the natural mineral clay is dried at 105℃±5℃ to a moisture content of <12%, and then pulverized in a Raymond mill to 60-100 mesh with a sieve pass rate of ≥95%.

3. The method for preparing organic soil remediation agent granules according to claim 1, characterized in that: The organic matter component in step one has a mass ratio of 15-30%, the humic acid content in the organic matter component is ≥50%, and the organic matter component is processed to 80-120 mesh before mixing.

4. The method for preparing organic soil remediation agent granules according to claim 1, characterized in that: In step one, the mass ratio of the particle reinforcing agent is 5-10%, and the particle reinforcing agent includes inorganic reinforcing agents and organic polymer binders. The inorganic reinforcing agent is magnesium sulfate, and its dosage accounts for 6-10% of the total dry basis. The organic polymer binder is polyacrylamide or sodium carboxymethyl cellulose, accounting for 1-2% of the total dry basis, and is prepared as a 1-2% aqueous solution when used.

5. The method for preparing organic soil remediation agent granules according to claim 1, characterized in that: The functional additive in step one has a mass ratio of 0.5% to 1.0%, and the functional additive is selected as a soil aggregation promoter, which is polyglutamic acid.

6. The method for preparing organic soil remediation agent granules according to claim 1, characterized in that: The functional additive in step one has a mass ratio of 0.5% to 1.0%, and the functional additive is a trace element supplement.

7. The method for preparing organic soil remediation agent granules according to claim 1, characterized in that: The mixer in step two is a double-helix mixer. The double-helix mixer mixes mineral clay powder, inorganic reinforcing agent and humic acid powder at 25-35 r / min for 10-15 min until the coefficient of variation of mixing uniformity CV ≤ 5%. Then the spray device is turned on and liquid organic polymer binder is added. The overall moisture content is controlled at 12-20%.

8. The method for preparing organic soil remediation agent granules according to claim 1, characterized in that: In step three, the inclined disc granulator has a disc diameter of 2-3m, an inclination angle of 45-55°, a rotation speed of 20-30r / min, and the atomizing nozzle sprays atomized water or dilute binder solution at a pressure of 0.2-0.4MPa with a spray volume of 2-5L / min. After granulation for 30–60 minutes, spherical particles of 2–6 mm are formed, with a sphericity rate of ≥85%.

9. The method for preparing organic soil remediation agent granules according to claim 1, characterized in that: In step four, the post-treatment curing involves low-temperature calcination at 200–300°C for 1–2 hours.

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