Material doped with coal gasification slag flow and preparation method thereof

Abstract

The invention discloses a material doped with coal gasification slag flow and a preparation method of the material, and belongs to the technical field of coal gasification slag recycling. Comprising the following raw materials in parts by weight: 35-45 parts of coal gasification slag, 10-18 parts of decomposed cow dung, 3-8 parts of calcium bentonite, 2-5 parts of polyacrylamide, 1-4 parts of potassium fulvate, 1-3 parts of sodium carboxymethyl cellulose, 10-20 parts of potash magnesium sulphate fertilizer and 15-25 parts of diammonium phosphate. According to the material doped with the coal gasification slag flow and the preparation method of the material, solid wastes such as coal gasification slag are converted into a functional fertilizer with an inner core-middle layer-outer shell unique structure, multiple synergy of long-acting slow release, efficient water retention and soil improvement is achieved, the solid wastes are efficiently digested, and meanwhile the soil improvement effect is improved. The utilization efficiency of the fertilizer and the stress resistance of crops are remarkably improved, the fertilization operation is simplified, and the fertilizer has outstanding environmental, economic and social benefits.

Description

Technical Field

[0001] This invention relates to the field of coal gasification slag recycling technology, and in particular to a material containing coal gasification slag and its preparation method. Background Technology

[0002] Coal gasification slag is a large-scale solid waste generated during the coal gasification process. Its main components are inorganic minerals such as silicon, aluminum, calcium, and iron, and it also contains trace elements. Currently, its disposal methods mainly rely on stockpiling and landfilling, which not only occupy a large amount of land but also pose environmental risks such as dust pollution and leaching contamination of soil and groundwater. Resource utilization is an inevitable trend. Existing technologies for using coal gasification slag in the fertilizer field mainly have the following limitations: Coal gasification slag has fine particles (0.3-1.5mm) and is magnetic, but it has a high water content and is prone to dust generation. Improper handling can cause groundwater pollution and soil acidification. Traditional landfill or incineration methods not only occupy land but may also release harmful gases. Current organic fertilizer production mostly uses agricultural waste, but research on the co-utilization of industrial waste is limited.

[0003] A common method is to simply dry and crush the gasification slag and use it as a soil conditioner or mix it with livestock manure, straw, etc. for ordinary composting. This method only utilizes its primary function as a silica-calcium filler or to provide trace elements, resulting in low added value. Furthermore, it cannot solve the fermentation problems caused by the lack of organic matter and the imbalance of carbon and nitrogen ratio in the gasification slag itself. The fertilizers prepared often have problems such as rapid nutrient release, poor water and fertilizer retention capacity, and limited functionality. Summary of the Invention

[0004] The purpose of this invention is to provide a material containing coal gasification slag and its preparation method, which transforms solid waste such as coal gasification slag into a functional fertilizer with a unique core-middle layer-outer shell structure. This achieves multiple synergies of long-term slow release, high-efficiency water retention and soil improvement. While efficiently disposing of solid waste, it significantly improves fertilizer utilization efficiency and crop stress resistance, simplifies fertilization operations, and has outstanding environmental, economic and social benefits.

[0005] To achieve the above objectives, the present invention provides a material containing coal gasification slag, comprising the following raw materials by mass: 35-45 parts coal gasification slag, 10-18 parts well-rotted cow manure, 3-8 parts calcium-based bentonite, 2-5 parts polyacrylamide, 1-4 parts potassium humate, 1-3 parts sodium carboxymethyl cellulose, 10-20 parts potassium magnesium sulfate fertilizer, and 15-25 parts diammonium phosphate.

[0006] The present invention also provides a method for preparing the above-mentioned material containing coal gasification slag, comprising the following steps: S1. The coal gasification slag, diammonium phosphate and potassium magnesium sulfate fertilizer are put into a high-speed mixer and dry-mixed to obtain a dry mixture. S2. The dry mixture obtained in S1 is fed into a fluidized bed granulator for spray granulation. During granulation, a first sodium carboxymethyl cellulose aqueous solution is sprayed to obtain wet granules. S3. Dry the wet particles obtained in S2 to obtain core particles; S4. The decomposed cow manure and calcium-based bentonite are premixed to obtain the first premixed dry powder. The core particles obtained in S3 are placed in a coating roller for coating operation. The first premixed dry powder is evenly sprinkled in during the coating operation. S5. Spray atomized water onto the material rolling in S4 to wet it, so as to fix the first premixed dry powder, and then dry it to obtain intermediate particles with an intermediate layer on the surface. S6. Polyacrylamide and potassium humate are dry-mixed evenly at room temperature to obtain a second premixed dry powder. The intermediate particles obtained in S5 are placed in a coating roller, and the second premixed dry powder is sprinkled in while the roller is rolling. Then, a second sodium carboxymethyl cellulose aqueous solution is sprayed on, and finally dried and cured to obtain a material mixed with coal gasification slag.

[0007] Preferably, in S1, the high-speed mixer rotates at 200-400 rpm and mixes for 5-10 minutes.

[0008] Preferably, in S2, granulation is carried out using a fluidized bed granulator with an inlet air temperature of 60-80℃, a material bed temperature of 40-60℃, a fluidizing air velocity of 1-2.5m / s, an atomizer rotation speed of 8000-15000rpm, and an atomization pressure of 0.2-0.6MPa.

[0009] Preferably, in S2, the first sodium carboxymethyl cellulose aqueous solution is prepared from sodium carboxymethyl cellulose accounting for 60-80% of the total amount of sodium carboxymethyl cellulose used, and the concentration is 4-7%.

[0010] Preferably, in step S3, a fluidized bed dryer is used for drying at a temperature of 60-70℃ for 2-4 hours until the moisture content is <5%.

[0011] Preferably, in S4, the roller speed for the coating operation is 10-30 rpm.

[0012] Preferably, in step S5, the humidification is achieved using atomized water, the drying temperature is 40-50℃, and the drying time is 1-2 hours until the moisture content is ≤6%.

[0013] Preferably, in S6, the drying temperature is 40-60℃, drying time is 1-3h until the moisture content is ≤10%, the maturation temperature is 20-30℃, and the maturation time is 12-24h.

[0014] Preferably, in S6, the second sodium carboxymethyl cellulose aqueous solution is prepared from sodium carboxymethyl cellulose accounting for 20-40% of the total amount of sodium carboxymethyl cellulose used, and the concentration is 2-4%.

[0015] Therefore, the present invention, employing the above-mentioned material containing coal gasification slag and its preparation method, has the following beneficial effects: (1) Using coal gasification slag as the main raw material, along with a variety of industrial and agricultural by-products such as decomposed cow manure and calcium-based bentonite, it is transformed into high-end functional fertilizer. This not only eliminates a large amount of solid waste, but also transforms it from an environmental burden into a resource product with high added value, thus achieving the circular economy goal of treating waste with waste and turning waste into treasure. (2) Through the three-step gradient granulation method, a clear gradient structure of high nutrient core - organic mineral intermediate layer - water-retaining slow-release shell is formed in the particle by self-assembly. This structure realizes the synergy of adsorption-net trapping-film formation triple slow-release barrier, so that the cumulative nutrient release rate of the product in 28 days can be controlled at ≤60%, which is far lower than that of ordinary fertilizers and simple mixed products, reaching the slow-release fertilizer standard, significantly prolonging the fertilizer effect and reducing nutrient loss; (3) Polyacrylamide is precisely positioned on the outer shell of the particles. When it comes into contact with water, it can form an effective three-dimensional gel network, making the product's water absorption ratio as high as 150-195%. This water-retaining network works synergistically with the osmotic regulation function of potassium humate, and can intelligently respond to changes in soil moisture, realize the synergistic release of water and nutrients in the gel network, effectively buffer drought stress, and improve the crop's drought resistance. (4) It integrates the mineral framework of gasification slag, the organic matter and active microorganisms of decomposed cow manure, the adsorption and exchange properties of bentonite, and the biostimulation effect of potassium humate. After application, it can replenish organic matter and achieve comprehensive improvement of soil physical, chemical and biological properties.

[0016] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0017] The technical solution of the present invention will be further described below through embodiments.

[0018] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0019] Example 1 This invention provides a material containing coal gasification slag, comprising the following raw materials by mass: 40 parts coal gasification slag, 14 parts well-rotted cow manure, 5 parts calcium-based bentonite, 3.5 parts polyacrylamide, 2.5 parts potassium humate, 2 parts sodium carboxymethyl cellulose, 15 parts potassium magnesium sulfate fertilizer, and 18 parts diammonium phosphate.

[0020] A method for preparing a material mixed with coal gasification slag includes the following steps: S1. Add coal gasification slag, diammonium phosphate, and potassium magnesium sulfate fertilizer into a high-speed mixer and mix at 300 rpm for 8 minutes.

[0021] S2. Feed the dry mixture from S1 into a fluidized bed granulator. Prepare a 5.5% aqueous solution from 70% of the total CMC as the first sodium carboxymethyl cellulose aqueous solution. Perform spray granulation at an inlet air temperature of 75℃, a bed temperature of 50℃, and an air velocity of 1.8m / s, with an atomizer speed of 12000rpm.

[0022] S3. After fluidized drying at 65℃ for 3 hours, core particles with a moisture content of 4.2% and a particle size of 1.5-2.0 mm are obtained.

[0023] S4. The decomposed cow manure and calcium-based bentonite are premixed to obtain the first premixed dry powder. The core particles are placed into a coating roller with a rotation speed of 20 rpm and the first premixed dry powder is evenly sprinkled on.

[0024] S5. Spray atomized water to wet, dry at 50℃ for 1.5h to obtain intermediate particles with a moisture content of 5.5% and a particle size of 2.5-3.0mm.

[0025] S6. PAM and potassium humate are dry-mixed to obtain a second premixed dry powder. The intermediate particles are placed in a coating roller and sprinkled with the second premixed dry powder. 30% of the total CMC is prepared into a 3% aqueous solution as a second sodium carboxymethyl cellulose aqueous solution for spraying. Subsequently, it is dried at 50℃ for 2 hours to a moisture content of 8.5%, and finally cured at 25℃ for 18 hours to obtain a finished product with a particle size of 3.5-4.0 mm.

[0026] Example 2 The only difference between this embodiment and Embodiment 1 is that, by mass, it includes the following raw materials: 36 parts coal gasification slag, 11 parts well-rotted cow manure, 3.5 parts calcium-based bentonite, 2.2 parts polyacrylamide, 1.2 parts potassium humate, 1.1 parts sodium carboxymethyl cellulose, 11 parts potassium magnesium sulfate fertilizer, and 16 parts diammonium phosphate. All other conditions are the same.

[0027] Example 3 The only difference between this embodiment and Embodiment 1 is that, by mass, it includes the following raw materials: 44 parts coal gasification slag, 17 parts well-rotted cow manure, 7.5 parts calcium-based bentonite, 4.8 parts polyacrylamide, 3.8 parts potassium humate, 2.9 parts sodium carboxymethyl cellulose, 19 parts potassium magnesium sulfate fertilizer, and 24 parts diammonium phosphate. All other conditions are the same.

[0028] Comparative Example 1 The only difference between this comparative example and Example 1 is that well-rotted cow manure and calcium-based bentonite are not added, steps S4 and S5 are omitted, and step S6 is performed directly after step S3. All other conditions are the same.

[0029] Comparative Example 2 The only difference between this comparative example and Example 1 is that a one-time mixing and granulation process is used, in which all raw materials are mixed at once, and then only water is sprayed for granulation and drying.

[0030] Comparative Example 3 The only difference between this comparative example and Example 1 is that sodium carboxymethyl cellulose is replaced with starch in the raw materials, and potassium humate is not added in S6. All other conditions are the same.

[0031] I. The properties of the materials obtained in Examples 1-3 and Comparative Examples 1-3 were measured, and the results are shown in Table 1.

[0032] Performance testing methods: Total nutrients (N+P2O5+K2O): Determination of total nitrogen content in compound fertilizers by distillation titration method (GB / T 8572-2010), Determination of available phosphorus content in compound fertilizers (GB / T 8573-2010), Determination of potassium content in compound fertilizers by potassium tetraphenylborate gravimetric method (GB / T 8574-2010); Organic matter content: 《Organic Fertilizer》 (NY / T 525-2021); pH value: Soil quality - Determination of pH (ISO 10390:2005); 28-day cumulative nutrient release rate: 《Slow-Release Fertilizers》 (GB / T 23348-2021); Water absorption ratio: 《Agricultural and Forestry Water Retention Agents》 (NY / T 886-2016); Particle compressive strength: Determination of crushing resistance of fertilizer catalyst particles (HG / T 2782-2011).

[0033] Table 1 Performance Test Results

[0034] As shown in Table 1, Examples 1-3 exhibited excellent sustained-release performance, benefiting from the gradient synergy of core adsorption, middle-layer buffering, and outer-layer entrapment film formation. Comparative Example 1, lacking the middle layer, resulted in accelerated nutrient release; Comparative Example 2, lacking a gradient structure, had a release rate as high as 90%, completely losing its sustained-release properties; Comparative Example 3 also showed a significant performance decline due to the incomplete outer-layer sustained-release components. This demonstrates that the three-step gradient granulation process is key to activating and integrating the functions of each raw material to achieve synergistic sustained release.

[0035] The materials prepared in Examples 1-3 possess both high organic matter content and high water retention. In Comparative Example 1, the organic matter content was significantly reduced due to the lack of an organic source. In Comparative Example 2, the water-retaining agent was simply mixed with other components, failing to form an effective network, resulting in almost complete loss of water retention function. This demonstrates that well-rotted cow manure, as an organic matter carrier, and the water-retaining agent, as a water-retaining network builder, need to be strategically positioned and distributed within a specific process to achieve the best synergistic effect.

[0036] The high particle strength in Examples 1-3 stems from the complementary reinforcement of the materials in each layer of the gradient structure. Comparative Examples 1 and 2, with their incomplete or homogeneous structures, exhibit significantly lower strength, demonstrating that the gradient structure itself makes a decisive contribution to the physical stability of the product.

[0037] II. Potted Plant Verification Experiment: Lettuce was used as the test crop, and the following treatments were set up: CK: blank, no fertilizer applied; CF: applied with ordinary commercially available compound fertilizer with equal total nutrients; T: applied with the material prepared in Example 1 of this invention. The nitrogen, phosphorus, and potassium nutrient inputs were consistent across all treatments, and the pot cultivation management conditions were the same. The biomass of the lettuce was measured after 45 days of growth.

[0038] The experimental results are shown in Table 2.

[0039] Table 2 Experimental Results

[0040] As shown in Table 2, under the same nutrient conditions, the fertilizer (T) of this invention significantly increased lettuce yield by 25.1% compared with ordinary compound fertilizer (CF), proving that it greatly improves nutrient utilization efficiency and crop growth promotion effect through slow release, water retention and multiple synergistic effects, and has clear yield increase potential.

[0041] III. Results of the Field Experiment: Experimental crop: maize; Experimental treatment: 1. CK group: No fertilizer was applied; 2. FP group: Apply conventional fertilization program (basal application of compound fertilizer 600 kg / ha, top dressing of urea 225 kg / ha). 3. IF group: 750 kg / ha of fertilizer prepared in Example 1 of this invention was applied as a single basal application. The total nutrient input was comparable to that of the FP treatment. No subsequent topdressing was required.

[0042] The experimental results are shown in Table 3.

[0043] Table 3 Experimental Results

[0044] As shown in Table 3, under the same total nutrient input, the fertilizer treatment of the present invention (IF) increased corn kernel yield by 12.7% compared with the local conventional fertilization (FP), demonstrating a significant yield increase effect. Furthermore, the nitrogen fertilizer partial productivity (PFPN) of the treatment of the present invention increased by 14.3%, proving that its slow-release characteristics reduced nutrient loss and improved nutrient utilization. The fertilizer of the present invention can meet the needs of corn throughout its entire growth period with a single basal application, eliminating the need for topdressing, saving labor costs, and meeting the needs of simplified agricultural development.

[0045] Therefore, the present invention adopts the above-mentioned material containing coal gasification slag and its preparation method to transform solid waste such as coal gasification slag into functional fertilizer with a unique core-middle layer-outer shell structure, realizing multiple synergies of long-term slow release, high-efficiency water retention and soil improvement. While efficiently disposing of solid waste, it significantly improves fertilizer utilization efficiency and crop stress resistance, and simplifies fertilization operations, thus having outstanding environmental, economic and social benefits.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A material containing coal gasification slag, characterized in that: By weight, it includes the following raw materials: 35-45 parts coal gasification slag, 10-18 parts well-rotted cow manure, 3-8 parts calcium-based bentonite, 2-5 parts polyacrylamide, 1-4 parts potassium humate, 1-3 parts sodium carboxymethyl cellulose, 10-20 parts potassium magnesium sulfate fertilizer, and 15-25 parts diammonium phosphate.

2. The preparation method of a material containing coal gasification slag as described in claim 1, characterized in that: Includes the following steps: S1. The coal gasification slag, diammonium phosphate and potassium magnesium sulfate fertilizer are put into a high-speed mixer and dry-mixed to obtain a dry mixture. S2. The dry mixture obtained in S1 is fed into a fluidized bed granulator for spray granulation. During granulation, a first sodium carboxymethyl cellulose aqueous solution is sprayed to obtain wet granules. S3. Dry the wet particles obtained in S2 to obtain core particles; S4. The decomposed cow manure and calcium-based bentonite are premixed to obtain the first premixed dry powder. The core particles obtained in S3 are placed in a coating roller for coating operation. The first premixed dry powder is evenly sprinkled in during the coating operation. S5. Spray atomized water onto the material rolling in S4 to wet it, so as to fix the first premixed dry powder, and then dry it to obtain intermediate particles with an intermediate layer on the surface. S6. Polyacrylamide and potassium humate are dry-mixed evenly at room temperature to obtain a second premixed dry powder. The intermediate particles obtained in S5 are placed in a coating roller, and the second premixed dry powder is sprinkled in while the roller is rolling. Then, a second sodium carboxymethyl cellulose aqueous solution is sprayed on, and finally dried and cured to obtain a material mixed with coal gasification slag.

3. The method for preparing a material mixed with coal gasification slag according to claim 2, characterized in that: In S1, the high-speed mixer rotates at 200-400 rpm and mixes for 5-10 minutes.

4. The method for preparing a material mixed with coal gasification slag according to claim 2, characterized in that: In S2, granulation is carried out using a fluidized bed granulator with an inlet air temperature of 60-80℃, a material bed temperature of 40-60℃, a fluidizing air velocity of 1-2.5m / s, a spray atomizer speed of 8000-15000rpm, and an atomization pressure of 0.2-0.6MPa.

5. The method for preparing a material mixed with coal gasification slag according to claim 2, characterized in that: In S2, the first sodium carboxymethyl cellulose aqueous solution is prepared from sodium carboxymethyl cellulose accounting for 60-80% of the total sodium carboxymethyl cellulose used, with a concentration of 4-7%.

6. The method for preparing a material mixed with coal gasification slag according to claim 2, characterized in that: In S3, a fluidized bed dryer is used for drying at a temperature of 60-70℃ for 2-4 hours until the moisture content is <5%.

7. The method for preparing a material mixed with coal gasification slag according to claim 2, characterized in that: In S4, the roller speed for coating operation is 10-30 rpm.

8. The method for preparing a material mixed with coal gasification slag according to claim 2, characterized in that: In S5, humidification is achieved using atomized water, and the drying temperature is 40-50℃, drying for 1-2 hours until the moisture content is ≤6%.

9. The method for preparing a material mixed with coal gasification slag according to claim 2, characterized in that: In S6, the drying temperature is 40-60℃, drying time is 1-3h until the moisture content is ≤10%, the maturation temperature is 20-30℃, and the maturation time is 12-24h.

10. The method for preparing a material mixed with coal gasification slag according to claim 2, characterized in that: In S6, the second sodium carboxymethyl cellulose aqueous solution is prepared from sodium carboxymethyl cellulose accounting for 20-40% of the total sodium carboxymethyl cellulose used, with a concentration of 2-4%.

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