Sandy soil compound modifier based on coal water slurry gasification slag as well as preparation method and application of sandy soil compound modifier

Abstract

The invention belongs to the technical field of soil improvement, and particularly relates to a sandy soil compound modifier based on coal water slurry gasification slag and a preparation method and application thereof. The invention provides a sandy soil compound modifier based on coal water slurry gasified slag. The sandy soil compound modifier comprises the following components in parts by mass: 0-20 parts of gasified coarse slag, 10-60 parts of gasified fine slag and 20-90 parts of sandy soil. The gasified coarse slag and the gasified fine slag generated in the coal water slurry gasification process are compounded with the sandy soil according to a specific proportion to prepare the improved soil, the volume weight of the aeolian sandy soil can be obviously reduced, the soil texture is gradually converted into loamy sandy soil from sandy soil and then converted into sandy loam, the soil texture of the aeolian sandy soil is improved, the soil pore structure is optimized, and the soil quality is improved. By means of the soil improvement method, resource utilization of coal chemical industry solid waste can be achieved, and meanwhile the problems that aeolian sandy soil is poor in water-retaining property and low in nutrient content are solved.

Description

Technical Field

[0001] This invention belongs to the field of soil improvement technology, specifically relating to a sandy soil compound conditioner based on coal-water slurry gasification slag, its preparation method, and its application. Background Technology

[0002] Aeolian sandy soil is a serious threat to the sustainable development of global agriculture. Its high sand content directly leads to problems such as soil structure damage, soil compaction and hardening, and decreased soil nutrient content, which in turn affect the normal growth and development of crop roots and their absorption and utilization of nutrients and water. Aeolian sandy soil is widely distributed in Northwest, North, and Northeast my country, with a bulk density as high as 1.54 g·cm⁻³ or more and a saturated water content of only about 24%, which seriously restricts local agricultural production and ecological environment construction.

[0003] Traditional methods for improving aeolian sandy soil mainly involve applying organic fertilizer, mixing imported soil with sand, and covering with protective mulch. However, traditional methods suffer from limited sources of organic fertilizer, high costs of imported soil, and short-lived effects. Currently, most soil conditioners on the market are chemically synthesized substances, which have problems such as high costs and secondary pollution to the environment. Moreover, existing soil improvement methods have limited effectiveness in improving aeolian sandy soil, and their marketization and industrialization levels are relatively low.

[0004] Coal-water slurry gasification technology is one of the important technologies in my country's coal chemical industry. During the gasification process, a large amount of solid waste, gasification slag, is generated. Gasification slag includes two types: coarse gasification slag and fine gasification slag. Coarse gasification slag is produced by melting, quenching, and condensation under high temperature and pressure conditions in the gasifier, and is discharged from the bottom of the gasifier. Its particle size is concentrated between 4750 and 10000 micrometers, with a high sand-like density, which can improve the pore structure of the soil. Fine gasification slag is produced by being carried out by the gas flow from the top of the gasifier and undergoing preliminary washing, purification, and sedimentation. Its particle size is less than 1000 micrometers, with a high clay content, and it has a strong adsorption capacity. Long-term stockpiling of this gasification slag not only occupies land resources but also easily pollutes the surrounding environment.

[0005] In existing technologies, research on the use of coal-based solid waste for soil improvement mainly focuses on fly ash. For example, Chinese patent (CN120266623A) discloses a method for promoting plant growth and improving soil based on fly ash. This involves adding 5-50% fly ash by mass to plant soil, selecting different plants as research subjects, observing plant growth, and screening for the optimal fly ash addition ratio. However, this method is mainly for acidic soils and has limited effectiveness in improving aeolian sandy soils. Chinese patent (CN119955527A) discloses a method for preparing soil conditioners using fly ash, but this requires the addition of organic matrix and microbial agents, making the process complex and costly. Chinese patent (CN120505105A) discloses a soil conditioner made of ferrous sulfate compounded with fly ash, its preparation method, and its application, but it is mainly used for saline-alkali land improvement and has limited applicability to aeolian sandy soils. The existing technologies mentioned above have the following shortcomings: they mostly use fly ash as raw material, while there is little research on the utilization of coal-water slurry gasification slag, and there is a lack of targeted improvement schemes for sandy soil.

[0006] While existing technologies utilize coal gasification slag to improve desertified soils, their core focus is on leveraging the porosity and multivalent cations of the gasification slag to promote soil particle aggregation, aiming to increase the total porosity of the soil. Therefore, this approach is insufficiently targeted at addressing the fundamental problem of water and fertilizer leakage caused by excessively large and interconnected pores in aeolian sandy soils. Simply increasing total porosity may not effectively optimize pore composition and may fail to transform the dominant ineffective large pores in aeolian sandy soils into effective water-retaining small pores. Furthermore, its improvement goals emphasize soil aggregate formation and nutrient enhancement, lacking a targeted approach to the directional transformation of aeolian sandy soil texture from sandy soil to loamy sandy soil and sandy loam, as well as pore structure optimization, especially capillary porosity improvement. Consequently, it cannot effectively solve the core problems of high macropore ratio and weak water and fertilizer retention capacity in aeolian sandy soils.

[0007] Therefore, designing a low-cost, efficient, and scalable modifier and method for utilizing industrial solid waste to address the problem of excessive porosity in aeolian sandy soil has become an urgent technical issue. Summary of the Invention

[0008] The purpose of this invention is to provide a sandy soil compound amendment based on coal-water slurry gasification slag, its preparation method, and its application. The purpose of this invention is not simply to increase pore size, but to specifically adjust and optimize pore size. By filling excessively large pores with specific materials, the pore size distribution is optimized, fundamentally improving the water-holding capacity of sandy soils. Specifically, coal-water slurry gasification slag is regarded as a physical filler material with a specific particle size distribution, rather than merely an additive that provides nutrients or promotes agglomeration. Through its particles, it physically fills and reconstructs excessively large non-capillary pores in sandy soils, thereby significantly reducing non-capillary porosity, increasing the proportion of capillary porosity, optimizing the three-phase distribution of the soil, and ultimately achieving a fundamental improvement in soil texture.

[0009] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A sand and soil compound amendment based on coal-water slurry gasification slag comprises the following components in parts by weight: 0-20 parts coarse gasification slag, 10-60 parts fine gasification slag, and 20-90 parts sand and soil.

[0010] Preferably, the components include the following parts by weight: 10-20 parts of coarse gasification slag, 10-60 parts of fine gasification slag, and 20-80 parts of sand.

[0011] Preferably, the components include the following parts by weight: 20 parts of coarse gasification slag, 60 parts of fine gasification slag, and 20 parts of sand.

[0012] Preferably, the gasification slag has a particle size of 4750~10000μm and a bulk density of 0.88g·cm³. -3 The saturated water content is 65%, and the cation exchange capacity is 7.81 cmol·kg⁻¹. -1 The loss on ignition rate was 16%.

[0013] Preferably, the gasification slag has a particle size of <1000μm and a bulk density of 0.36g·cm³. -3 The saturated water content is 224%, and the cation exchange capacity is 3.88 cmol·kg⁻¹. -1 The loss on ignition rate was 29%.

[0014] This invention also provides a method for preparing the sand and soil compound amendment based on coal-water slurry gasification slag, comprising the following steps: The coarse gasification slag and the fine gasification slag are mixed to obtain a mixture; The mixture is mixed with sand to obtain the compound amendment.

[0015] The present invention further provides the application of the sand and soil compound amendment based on coal-water slurry gasification slag in improving the water retention performance of sand and soil.

[0016] Preferably, the method is as follows: filling and improving the pore structure of aeolian sandy soil with coal-water slurry gasification slag, including the following steps: using the coarse gasification slag and / or fine gasification slag produced in the coal-water slurry gasification process as a filling and improving agent, and physically compounding it with the target aeolian sandy soil. The compound is designed to significantly reduce the non-capillary porosity of sandy soil and optimize soil texture. The gasified slag particles fill the large air-permeable pores in the sandy soil, thereby transforming the texture of the improved soil from sandy soil to loamy sandy soil or sandy loam.

[0017] The present invention further provides the application of the sand and soil compound amendment based on coal-water slurry gasification slag as a base fertilizer.

[0018] Preferably, after the spring thaw, the coal-water slurry gasification residue is mechanically spread evenly on the ground surface, plowed, and then rotary tilled to a depth of 20-30 cm before sowing; the amount of coal-water slurry gasification residue used is 10500 kg·hm². -2 .

[0019] The present invention has the following beneficial technical effects: This invention is the first to explicitly propose using gasification slag as a physical filler, utilizing its particle size distribution to reduce and optimize the excessive macropores and insufficient capillary pores in aeolian sandy soil. The core purpose is to reconstruct the pore composition, rather than simply increasing pore size. The formulation of this invention is designed based on the specific purpose of filling and optimizing the pore structure of aeolian sandy soil, particularly increasing the proportion of clay and silt particles. In contrast, the formulations of existing technologies, with coarse slag:fine slag ratios of 1~5:1 and a total addition amount of 10~60%, are based on the purpose of promoting agglomeration and increasing total porosity.

[0020] The sand-soil compound gasification slag amendment provided by this invention includes coarse gasification slag and fine gasification slag. The gasification slag mainly originates from solid waste generated in coal chemical production. Long-term stockpiling of this slag not only occupies land resources but also easily pollutes the surrounding environment. Annual treatment also consumes significant manpower and resources. However, the slag itself contains spherical particles on its surface, and its loose surface allows for a large specific surface area, giving it good water permeability and water retention capacity. Adding it to soil amendment helps improve soil pore structure, increase porosity and water-holding capacity, thus improving soil structure. Furthermore, it can improve the overall utilization efficiency of resources, thereby aligning with the sustainable development concept of resource recycling.

[0021] The sand and soil compound gasification slag improvement method provided by this invention can reduce the bulk density of the soil itself. The reduction in bulk density helps to improve the soil pore structure and increase the soil's water retention and fertilizer retention capacity. For the improvement of sandy soil, the gasification slag is the main component. As the amount of gasification slag added increases, the texture of the sandy soil gradually changes from sandy soil to loamy sandy soil and then to sandy loamy soil. This reduces the bulk density of the sandy soil, improves the texture of the sandy soil, optimizes the soil pore structure, reduces soil porosity, and has a significant effect on improving the particle size of sandy soil.

[0022] Experiments show that the sand-soil composite gasification slag improvement method provided by this invention can improve the bulk density of sandy soil and significantly reduce the bulk density of aeolian sandy soil. Specifically, the small particles in the gasification slag can fill the pores of the soil, increasing the internal porosity and pore surface area, thereby improving the soil pore structure, water retention capacity, and capillary porosity. Furthermore, the increasing proportion of clay and silt in the sand-soil composite gasification slag improvement method provided by this invention can improve the loose texture and large porosity of aeolian sandy soil, gradually transforming the soil texture from sandy soil to loamy sandy soil and then to sandy loam. This helps to improve aeolian sandy soil towards loam, thus improving its soil texture.

[0023] This invention enhances the water and fertilizer retention capacity of sandy soil by utilizing solid waste, while simultaneously achieving closed-loop utilization of agricultural waste. This reduces costs by over 40% compared to traditional soil conditioners and avoids the soil compaction risks associated with chemical conditioners. Furthermore, the sand-soil compound gasification slag improvement method provided by this invention addresses the current problems of the Mu Us Desert sandy soil, which is characterized by predominantly large aeration pores, poor compaction, weak water and fertilizer retention capacity, and easy nutrient loss. In addition, the sand-soil compound gasification slag improvement method provided by this invention has the advantages of simple operation and suitability for industrial production.

[0024] The results of the examples show that the addition of different gasification slags increased the soil organic carbon content by more than 25%, and both types of gasification slags significantly increased the total phosphorus content of the soil. The total phosphorus content of the gasification slags in dryland soils was 1.93-3.03 times higher than that of the control, and the total phosphorus content of the gasification slags in paddy fields was 1.64-2.00 times higher than that of the control. The saturated water content of the gasification slags was significantly higher than that of the control, namely 65% ​​for coarse gasification slags and 224% for fine gasification slags. The field water holding capacity of coarse gasification slags and fine gasification slags was 2 times and 5.17 times that of the control, respectively. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below.

[0026] Figure 1The following is a scanning electron microscope (SEM) analysis of the gasification slag and sand in this invention: a and b are coarse gasification slag, and c and d are sand; a and c are 10 μm scale bars, and b and d are 100 μm scale bars. Figure 2 For the elemental analysis of the gasification slag and sand surface of the present invention, a) surface metal element analysis, b) surface heavy metal element analysis; Figure 3 This is a triangular coordinate diagram for classifying the texture of sandy soil in this invention, where a represents CK and b~f represent formulas 1~8; Figure 4 The results of this invention show the particle size composition of different gasification slag mixes and sandy soils. Figure 5 The results show the porosity of different gasification slag and sandy soils in this invention. a represents CK, and PF-1-8 represents formulations 1 to 8. Detailed Implementation

[0027] This invention provides a sand and soil compound amendment based on coal-water slurry gasification slag, comprising the following components in parts by weight: 0-20 parts of coarse gasification slag, 10-60 parts of fine gasification slag, and 20-90 parts of sand and soil.

[0028] In this invention, the sand and soil compound amendment preferably comprises the following components in parts by weight: 10-20 parts of coarse gasification slag, 10-60 parts of fine gasification slag, and 20-80 parts of sand and soil. In one embodiment of the present invention, the sand and soil compound amendment preferably comprises the following components in parts by weight: 20 parts of gasification coarse slag, 50 parts of gasification fine slag, and 30 parts of sand.

[0029] In another embodiment of the present invention, the sand and soil compound amendment more preferably includes the following components in parts by weight: 20 parts of gasification coarse slag, 60 parts of gasification fine slag, and 20 parts of sand.

[0030] In this invention, the coarse and fine gasification slags are preferably derived from solid waste in coal chemical production; more preferably, the gasification slags are derived from Inner Mongolia Boda Shidi Chemical Co., Ltd. in Uxin Banner, Ordos. Specifically, a coal-water slurry additive is added to the raw coal and mixed with water in a coal mill to form a coal-water slurry. The coal-water slurry is then transported to a gasifier. The coal-water slurry and oxygen from the air are injected into the combustion chamber of the gasifier and fully combusted at a high temperature of 1300°C. The gasification residue after full combustion flows downward into the bottom quench chamber for cooling and solidification. The solidified gasification residue is crushed by a slag crusher and enters a slag collector. It is then transported by belt to a gasification residue treatment center for processing to form gasification slag.

[0031] The long-term storage of gasification slag not only occupies land resources and easily pollutes the surrounding environment, but also consumes a lot of manpower and resources for treatment every year. However, its surface contains some spherical particles, and its loose surface gives it a large specific surface area, which gives it good water permeability and water retention capacity. When it is used for soil improvement, it helps to improve the soil pore structure, increase porosity and soil water holding capacity, and play a role in improving soil structure. In addition, it can also improve the overall utilization efficiency of resources, thereby achieving the role of aligning with the concept of sustainable development of resource recycling.

[0032] In this invention, the preferred particle size of the gasification coarse slag is 4750~10000μm, and the preferred bulk density is 0.88g·cm³. -3 The saturated water content is preferably 65%, and the cation exchange capacity is preferably 7.81 cmol·kg⁻¹. -1 The preferred loss on ignition is 16%; the preferred particle size of the gasified fine slag is <1000μm, and the preferred bulk density is 0.36g·cm³. -3 The saturated water content is preferably 224%, and the cation exchange capacity is preferably 3.88 cmol·kg⁻¹. -1 The preferred loss on ignition rate is 29%.

[0033] Through in-depth research, the inventors have realized that not all coal gasification slag is suitable for improving aeolian sandy soil, nor is simple mixing sufficient. To achieve effective filling and fundamental improvement of the water-holding capacity of aeolian sandy soil's large pores, it is necessary to utilize gasification slag with specific physicochemical properties. The coal-water slurry gasification slag used in this invention has a coarse gasification slag with a large particle size (4750~10000μm) and high strength, suitable for constructing a soil framework; while its fine gasification slag exhibits extremely low bulk density and high saturated water content, while also possessing a certain cation exchange capacity and a high loss on ignition rate. The coarse and fine slags perfectly complement each other in terms of physical properties. The coarse slag, as a structural component, optimizes the distribution of large pores; the fine slag, as a functional filling and water-holding component, with its porous, lightweight, and high water-holding capacity, occupies pores while transforming the original air channels into capillary pores. Therefore, when filling the pores of aeolian sandy soil, it not only occupies physical space but also directly integrates water storage capacity. Meanwhile, the appropriate particle size of the coarse slag ensures that the soil retains good aeration after filling. The synergy of these two factors results in a significant reduction in non-capillary porosity and a substantial increase in capillary porosity in the improved soil, optimizing the three-phase structure of the soil and fundamentally altering its texture.

[0034] This invention also provides a method for preparing the sand and soil compound amendment based on coal-water slurry gasification slag, comprising the following steps: The coarse gasification slag and the fine gasification slag are mixed to obtain a mixture; The mixture is mixed with sand to obtain the compound amendment.

[0035] The present invention further provides the application of the sand and soil compound amendment based on coal-water slurry gasification slag in improving the water retention performance of sand and soil.

[0036] Preferably, the method is as follows: filling and improving the pore structure of aeolian sandy soil with coal-water slurry gasification slag, including the following steps: using the coarse gasification slag and / or fine gasification slag produced in the coal-water slurry gasification process as a filling and improving agent, and physically compounding it with the target aeolian sandy soil. The compound is designed to significantly reduce the non-capillary porosity of sandy soil and optimize soil texture. The gasified slag particles fill the large air-permeable pores in the sandy soil, thereby transforming the texture of the improved soil from sandy soil to loamy sandy soil or sandy loam.

[0037] The present invention further provides the application of the sand and soil compound amendment based on coal-water slurry gasification slag as a base fertilizer.

[0038] Preferably, after the spring thaw, the coal-water slurry gasification residue is mechanically spread evenly on the ground surface, plowed, and then rotary tilled to a depth of 20-30 cm before sowing; the amount of coal-water slurry gasification residue used is 10500 kg·hm². -2 .

[0039] Example 1: A method for sand and soil compounding improvement based on coal-water slurry gasification slag, comprising the following steps: The sandy soil in the experimental area was improved by compounding the mixture with a ratio of 10 parts gasified fine slag and 90 parts aeolian sandy soil from the experimental area. After the soil thawed in spring, the prepared gasified slag was evenly spread on the surface of the target aeolian sandy soil using a fertilizer spreader. Then, a moldboard plow was used for tilling, and immediately a rotary tiller was used to thoroughly mix the improver with the topsoil. The tillage depth was controlled at 20-30 cm.

[0040] Example 2 A method for sand and soil compounding improvement based on coal-water slurry gasification slag, comprising the following steps: The sandy soil in the experimental area was compounded and improved using a mixture of 20 parts gasified fine slag and 80 parts aeolian sandy soil from the experimental area. After the soil thawed in spring, the prepared gasified slag was evenly spread on the surface of the target aeolian sandy soil using a fertilizer spreader. Then, a moldboard plow was used for tilling, and immediately a rotary tiller was used to thoroughly mix the improver with the topsoil. The tillage depth was controlled at 20-30 cm.

[0041] Example 3 A method for sand and soil compounding improvement based on coal-water slurry gasification slag, comprising the following steps: The sandy soil in the experimental area was compounded and improved using a mixture of 10 parts coarse gasification slag, 20 parts fine gasification slag, and 70 parts aeolian sandy soil from the experimental area. After the soil thawed in spring, the prepared gasification slag was evenly spread on the surface of the target aeolian sandy soil using a fertilizer spreader. Subsequently, the soil was plowed using a moldboard plow, and immediately a rotary tiller was used to thoroughly mix the improver with the topsoil. The tillage depth was controlled at 20-30 cm.

[0042] Example 4 A method for sand and soil compounding improvement based on coal-water slurry gasification slag, comprising the following steps: The sandy soil in the experimental area was compounded and improved using a mixture of 10 parts coarse gasification slag, 30 parts fine gasification slag, and 60 parts aeolian sandy soil from the experimental area. After the soil thawed in spring, the prepared gasification slag was evenly spread on the surface of the target aeolian sandy soil using a fertilizer spreader. Subsequently, the soil was plowed using a moldboard plow, and immediately a rotary tiller was used to thoroughly mix the improver with the topsoil. The tillage depth was controlled at 20-30 cm.

[0043] Example 5 A method for sand and soil compounding improvement based on coal-water slurry gasification slag, comprising the following steps: The sandy soil in the experimental area was compounded and improved using a mixture of 10 parts coarse gasification slag, 40 parts fine gasification slag, and 50 parts aeolian sandy soil from the experimental area. After the soil thawed in spring, the prepared gasification slag was evenly spread on the surface of the target aeolian sandy soil using a fertilizer spreader. Subsequently, the soil was plowed using a moldboard plow, and immediately a rotary tiller was used to thoroughly mix the improver with the topsoil. The tillage depth was controlled at 20-30 cm.

[0044] Example 6 A method for sand and soil compounding improvement based on coal-water slurry gasification slag, comprising the following steps: The sandy soil in the experimental area was compounded and improved using a mixture of 20 parts coarse gasification slag, 40 parts fine gasification slag, and 40 parts aeolian sandy soil from the experimental area. After the soil thawed in spring, the prepared gasification slag was evenly spread on the surface of the target aeolian sandy soil using a fertilizer spreader. Subsequently, the soil was plowed using a moldboard plow, and immediately a rotary tiller was used to thoroughly mix the improver with the topsoil. The tillage depth was controlled at 20-30 cm.

[0045] Example 7 A method for sand and soil compounding improvement based on coal-water slurry gasification slag, comprising the following steps: The sandy soil in the experimental area was compounded and improved using a mixture of 20 parts coarse gasification slag, 50 parts fine gasification slag, and 30 parts aeolian sandy soil from the experimental area. After the soil thawed in spring, the prepared gasification slag was evenly spread on the surface of the target aeolian sandy soil using a fertilizer spreader. Subsequently, the soil was plowed using a moldboard plow, and immediately a rotary tiller was used to thoroughly mix the improver with the topsoil. The tillage depth was controlled at 20-30 cm.

[0046] Example 8 A method for sand and soil compounding improvement based on coal-water slurry gasification slag, comprising the following steps: The sandy soil in the experimental area was compounded and improved using a mixture of 20 parts coarse gasification slag, 60 parts fine gasification slag, and 20 parts aeolian sandy soil from the experimental area. After the soil thawed in spring, the prepared gasification slag was evenly spread on the surface of the target aeolian sandy soil using a fertilizer spreader. Subsequently, the soil was plowed using a moldboard plow, and immediately a rotary tiller was used to thoroughly mix the improver with the topsoil. The tillage depth was controlled at 20-30 cm.

[0047] Experimental Example 1 In Uxin Banner, Ordos City, Inner Mongolia (Mu Us Desert sandy soil), sandy soil samples of 0-50cm depth were selected to analyze the basic physicochemical properties of the coal-water slurry gasification residue used in the project area, including physical properties such as soil bulk density, porosity, texture, and particle size distribution. The feasibility of reconstructing the soil's physicochemical indicators through different soil formulations was analyzed. The gasification residue was obtained from Ordos Uxin Banner Boda Fertilizer Co., Ltd. Experimental equipment included a laser particle size analyzer, a spatula, a wooden sieve, and a 1mm sieve. The sandy soil improvement formulation experiment employed a three-factor, multi-level, nine-treatment orthogonal experimental design, with three replicates for each treatment.

[0048] The preferred test gasification residue came from Boda Shidi Chemical Co., Ltd. in Wushen Banner, Ordos City, Inner Mongolia. After the spring thaw, the coal-water slurry gasification residue was evenly spread on the ground surface by machinery, and then plowed and rotary tilled to a depth of 20-30cm.

[0049] Soil particle size distribution was determined using a laser particle size analyzer. The simplified procedure involved air-drying the soil and gasification slag in a cool, shaded area, thoroughly compacting them with a wooden trowel, and then sieving them through a 1mm sieve. The sieved soil samples from each treatment were then placed into the laser particle size analyzer for measurement, and the data were processed using the Talwin particle size analysis software to determine the particle size distribution and soil texture. The results are as follows: Figures 3 to 5 As shown.

[0050] The results showed that, compared with the unmodified control sandy soil (CK), the soil physical structure was significantly improved after treatment with the filler amendments of the present invention (formulas 1-8). With the increase of the proportion of gasification slag incorporated, the soil bulk density decreased significantly and systematically (P<0.05), with the bulk density of formula 8 decreasing by 55.5% compared to CK. Simultaneously, the soil texture underwent a fundamental transformation: the sand content significantly decreased, while the proportion of clay and silt significantly increased (P<0.05), gradually improving the soil texture from the original sandy soil to loamy sandy soil, and ultimately optimizing it into sandy loam. Regarding pore structure, the capillary porosity of the improved soil significantly increased (P<0.05), while the non-capillary porosity significantly decreased, and the total porosity showed an upward trend. This indicates that the amendments of the present invention effectively optimized the soil pore composition and enhanced the soil's water retention capacity.

[0051] In summary, the filler modifier based on coal-water slurry gasification slag provided by this invention can effectively reduce the bulk density of sandy soil, improve its particle size distribution, optimize soil texture, and improve pore structure, transforming extremely poor sandy soil into ideal loam, thereby creating a more favorable soil physical environment for crop growth. Among them, formulations 7 and 8 (i.e., the total amount of gasification slag incorporated ≥70%) have a particularly significant effect on improving soil texture.

[0052] As can be seen from the above embodiments, the present invention provides a method for improving sandy soil based on coal-water slurry gasification slag. The gasification slag in this method mainly functions to regulate soil bulk density, improve the texture of aeolian sandy soil, and improve soil pore structure. Experiments show that the sandy soil improvement method based on gasification slag provided by the present invention can effectively improve soil permeability in the Mu Us Desert region, accelerate soil moisture transport, enhance soil water retention, improve soil structure, and promote sustainable agricultural development.

[0053] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A sand and soil compound amendment based on coal-water slurry gasification slag, characterized in that, The components include the following parts by weight: 0-20 parts of coarse gasification slag, 10-60 parts of fine gasification slag, and 20-90 parts of sand.

2. The sand and soil compound amendment based on coal-water slurry gasification slag according to claim 1, characterized in that, The components include the following parts by weight: 10-20 parts of coarse gasification slag, 10-60 parts of fine gasification slag, and 20-80 parts of sand.

3. The sand and soil compound amendment based on coal-water slurry gasification slag according to claim 1, characterized in that, The components include the following parts by weight: 20 parts coarse gasification slag, 60 parts fine gasification slag, and 20 parts sand.

4. The sand and soil compound amendment based on coal-water slurry gasification slag according to claim 1, characterized in that, The gasification slag has a particle size of 4750~10000μm and a bulk density of 0.88g·cm³. -3 The saturated water content is 65%, and the cation exchange capacity is 7.81 cmol·kg⁻¹. -1 The loss on ignition rate was 16%.

5. The sand and soil compound amendment based on coal-water slurry gasification slag according to claim 1, characterized in that, The gasification slag has a particle size of <1000μm and a bulk density of 0.36g·cm³. -3 The saturated water content is 224%, and the cation exchange capacity is 3.88 cmol·kg⁻¹. -1 The loss on ignition rate was 29%.

6. The method for preparing the sand and soil compound amendment based on coal-water slurry gasification slag according to any one of claims 1 to 5, characterized in that, Includes the following steps: The coarse gasification slag and the fine gasification slag are mixed to obtain a mixture; The mixture is mixed with sand to obtain the compound amendment.

7. The application of the sand and soil compound modifier based on coal-water slurry gasification slag as described in any one of claims 1 to 5 and the compound modifier prepared according to claim 6 in improving the water retention performance of sand and soil.

8. The application according to claim 7, characterized in that, Specifically, the method of filling and improving the pore structure of aeolian sandy soil with coal-water slurry gasification slag includes the following steps: using the coarse gasification slag and / or fine gasification slag produced during the coal-water slurry gasification process as filling and improving agents, and physically compounding them with the target aeolian sandy soil. The compound is designed to significantly reduce the non-capillary porosity of sandy soil and optimize soil texture. The gasified slag particles fill the large air-permeable pores in the sandy soil, thereby transforming the texture of the improved soil from sandy soil to loamy sandy soil or sandy loam.

9. The application of the sand and soil compound amendment based on coal-water slurry gasification slag as described in any one of claims 1 to 5 and the compound amendment prepared according to claim 6 as a base fertilizer.

10. The application according to claim 9, characterized in that, After the spring thaw, the coal-water slurry gasification residue is evenly spread on the ground using machinery, plowed, and then rotary tilled to a depth of 20-30 cm before sowing; the amount of coal-water slurry gasification residue used is 10500 kg·hm². -2 .

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