A soil conditioner prepared by modifying high-phosphorus smelting slag and a method thereof

Abstract

The application belongs to the field of soil treatment, and particularly relates to a soil conditioner prepared by modifying high-phosphorus smelting slag and a method, which comprises the following steps: S1, uniformly mixing an additive with high-phosphorus slag according to the component composition of the high-phosphorus slag, adjusting the binary basicity of the final slag to be 1.0-2.0, and then grinding to obtain metallurgical slag with uniform mixing; wherein the phosphorus content in the high-phosphorus slag is 1%-10%, and the FeO content is 5%-50%; S2, placing the metallurgical slag into a heating furnace to heat, the heating temperature is 1500 DEG C-1800 DEG C, after all the substances are melted into a liquid state and kept for 30 min-1.5 h, the molten slag is rapidly cooled to room temperature; S3, drying and finely grinding the molten slag obtained in S2 to obtain the soil conditioner. The method of the application utilizes the originally discarded metallurgical high-phosphorus slag in a high-value way, and recovers a large amount of valuable P resources, and is worthy of vigorous promotion and application.

Description

Technical Field

[0001] This invention belongs to the field of soil remediation, specifically relating to a soil conditioner and method prepared by modifying high-phosphorus smelting slag. Background Technology

[0002] Soil conditioners play a vital role in soil management. They effectively improve the physical and chemical properties of soil, such as increasing soil aeration, permeability, and water retention, thereby creating a more suitable environment for crop growth. Soil conditioners also balance soil pH, regulate nutrient supply, and promote the activity of beneficial microorganisms, keeping the soil healthy. This not only helps improve crop yield and quality but also reduces excessive reliance on chemical fertilizers and water resources, promoting the development of eco-friendly agriculture and providing crucial support for ensuring food security and protecting the environment.

[0003] High-phosphorus iron ore resources are widely distributed globally, with proven reserves exceeding 20 billion tons. With the rapid consumption of high-quality iron ore and continuous advancements in smelting technology, previously difficult-to-utilize high-phosphorus iron ore resources are gradually becoming another direction for expanding the selection of ironmaking raw materials. Therefore, the phosphorus content in metallurgical slag produced during the smelting process is constantly increasing, and the internal recycling within steel plants further leads to the cyclical enrichment of phosphorus in the slag. Thus, the development and utilization of high-phosphorus metallurgical slag is now imperative.

[0004] Furthermore, the inventors' research group has been focusing on the development of efficient smelting technology for high-phosphorus iron ore and the high-value utilization of solid waste from the metallurgical industry. They have also been collaborating extensively with a high-phosphorus iron ore smelting project in Algeria, aiming to develop a production process suited to its resource structure. Given Algeria's abundant high-phosphorus iron ore and natural gas resources, the research group previously disclosed a two-step method for efficient iron-phosphorus separation from high-phosphorus iron-containing resources based on gas-based energy (patent number ZL 2020104955182). As the project progressed, it was discovered that smelting high-phosphorus iron ore using this method generates an average of one ton of high-phosphorus smelting slag for every ton of steel produced, containing approximately 60-120 kg of phosphorus. Indiscriminate disposal of this slag would result in a significant waste of valuable phosphorus resources. Algeria is primarily characterized by Mediterranean and desert climates, with arid and low-rainfall areas near the desert, making water resources extremely precious. Considering the characteristics of the smelting process and the country's resource conditions, developing and utilizing the large amount of high-phosphorus smelting slag generated during smelting to simultaneously recover phosphorus and conserve soil water is of great significance. Summary of the Invention

[0005] To achieve the above objectives and solve the above problems, the present invention provides a soil conditioner and method for preparing a modified high-phosphorus smelting slag. By modifying phosphorus slag (such as smelting slag produced by rapid reduction smelting process), a glassy phase soil conditioner with a porous structure is generated. On the one hand, it realizes the recycling and utilization of high-phosphorus smelting slag, a solid waste from the metallurgical industry, to improve soil. After activation treatment, phosphorus and calcium elements in the slag can be slowly released into the soil, providing a variety of beneficial nutrients while maintaining high soil moisture. On the other hand, it also solves the problem of low utilization rate of phosphorus-containing slag and large-scale waste of phosphorus resources after smelting high-phosphorus iron ore.

[0006] According to a first aspect of the present invention, a method for preparing a soil conditioner by modifying high-phosphorus smelting slag is provided, comprising:

[0007] S1. Based on the composition of high-phosphorus smelting slag, the additives are mixed evenly with the high-phosphorus smelting slag, and the binary basicity of the final slag is adjusted to 1.0-2.0. Then, the slag is ground to obtain a uniformly mixed metallurgical slag.

[0008] S2. The metallurgical slag is placed in a heating furnace and heated until all the substances melt into a liquid state. After heat preservation, the slag is rapidly cooled to room temperature.

[0009] S3. The slag is dried and finely ground to obtain a soil conditioner.

[0010] It should be noted that the soil conditioner in the technical solution of this application specifically refers to one that can slow-release fertilizer and has water retention function.

[0011] Furthermore, the high-phosphorus smelting slag in S1 is the smelting slag produced by the rapid reduction smelting process, the ironmaking and steelmaking slag produced during the long-process smelting process, or the high-phosphorus slag produced by various industries.

[0012] Furthermore, the rapid reduction melting process specifically includes:

[0013] High-phosphorus iron-containing resources, carburizing agent, flux, and binder are added and mixed in a predetermined ratio. After wetting with an appropriate amount of water and mixing again, the mixture is pressed into lumps with a certain compressive strength. The carburizing agent is anthracite or coke powder, with a fixed carbon content of about 80%, an ash content of less than 15%, and a particle size of less than 1 mm. The maximum basicity of the lumps is 2.0. The carburizing agent is 0-2% of the weight of the iron-containing material. The flux is limestone and industrial-grade sodium carbonate, with the industrial-grade sodium carbonate content being 0-3% of the weight of the iron-containing material.

[0014] After drying, the lumps are loaded into a vertical shaft furnace for gas-based reduction. The reducing gas comes from natural gas and the tail gas of the reduction furnace reforming to produce metallized lumps.

[0015] The metallized lumps are discharged and directly charged into a melting furnace for rapid melting and separation using methods such as natural gas combustion, plasma torch, or electric arc heating. After water quenching and magnetic separation, solid granular pig iron and glass slag are produced. In the gas-based melting furnace, natural gas burners are used to rapidly heat the metallized lumps, achieving rapid slag-iron separation. The molten pig iron or semi-steel and slag after melting and separation are quickly discharged into a water tank for water quenching, thus obtaining the molten slag.

[0016] Furthermore, the high-phosphorus smelting slag is in a solid or high-temperature molten state.

[0017] Furthermore, the phosphorus content in the high-phosphorus smelting slag is 1%-10%, the FeO content is 5%-50%, and the slag does not contain heavy metal elements that pollute the soil.

[0018] Preferably, the main components of the high-phosphorus smelting slag are FeO content of 10%, P content of 5%, MgO content of 5%, Al2O3 content of 10.5%, CaO and SiO2 content of approximately 30%, and C content of 2%.

[0019] Furthermore, the suitable binary basicity of the endpoint residue in S1 is 1.7-2.0.

[0020] Furthermore, the additive in S1 is an alkalinity regulator.

[0021] Furthermore, the alkalinity regulator in S1 is quartz (SiO2), quicklime (CaO), or limestone (CaCO3).

[0022] Furthermore, in step S2, the heating temperature is 1500℃-1800℃; the holding time after complete melting is 30min-1.5h, and nitrogen is used as a protective gas.

[0023] Furthermore, the rapid cooling in S2 is air cooling, atomization cooling, or water cooling.

[0024] Furthermore, the cooling time to room temperature in S2 is 5s-30s, in order to control the proportion of amorphous phase in the slag to be greater than 30%.

[0025] Furthermore, the finely ground soil conditioner in S3 has a particle size between 50 mesh and 300 mesh.

[0026] Furthermore, in step S3, the soil conditioner is uniformly dispersed 2-15 cm below the soil surface.

[0027] Furthermore, in step S3, the amount of soil conditioner used is 100-2000 kg / mu.

[0028] According to a second aspect of the present invention, a soil conditioner prepared by modifying high-phosphorus smelting slag is provided, wherein the soil conditioner is prepared by the method described in any of the above aspects.

[0029] Furthermore, the soil conditioner has a citric acid-soluble phosphorus content of 20-80%.

[0030] Compared with existing technologies, the soil conditioner preparation method in this invention is simple. It modifies high-phosphorus metallurgical slag by altering its composition and physical state, combined with adjustments to the alkalinity and cooling rate. The amorphous phase in the modified soil conditioner not only increases the specific surface area of ​​the slag, retaining moisture and inhibiting evaporation, but also combines with water to form hydrates, further suppressing water loss and significantly improving water retention. Simultaneously, the modified and activated soil conditioner can slowly release nutrients such as Ca, Si, and P into the soil, providing slow-release inorganic fertilizers for plants. This is particularly suitable for arid and infertile areas, ensuring a slow-release effect. This invention makes high-value use of previously discarded high-phosphorus metallurgical slag, recovering a large amount of valuable phosphorus resources, and is worthy of widespread application. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0032] Figure 1 A flowchart illustrating a method for preparing a soil conditioner using high-phosphorus smelting slag modification according to an embodiment of the present invention is shown.

[0033] Figure 2 A schematic diagram of the modified slag according to an embodiment of the technical solution of the present invention is shown;

[0034] Figure 3 A schematic diagram showing the effect of slag with different basicities on citrate-soluble phosphorus and water-soluble phosphorus is shown.

[0035] Figure 4 A schematic diagram showing the water retention effect of an embodiment of the technical solution according to the present invention and a blank control group is presented.

[0036] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0037] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0038] The terms "first," "second," etc., used in this disclosure are for distinguishing similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that the embodiments of this disclosure described herein can be implemented, for example, in orders other than those illustrated or described herein.

[0039] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0040] Multiple, including two or more.

[0041] And / or, it should be understood that, for the purposes of this disclosure, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone.

[0042] This invention provides a soil conditioner and method for preparing a modified high-phosphorus smelting slag. By controlling alkalinity and cooling rate, the high-phosphorus smelting slag is reconstructed to prepare a soil conditioner with both water retention and nutrient release functions. This method is innovative and practical. Compared with methods for enriching phosphorus in crystalline slag, the operation of modifying smelting slag using this method is simpler and more efficient, while exhibiting significantly better slow-release of nutrients and superior water retention. Furthermore, no other waste is generated throughout the entire process.

[0043] Specifically, the technical solution of this invention first provides a method for preparing a soil conditioner by modifying high-phosphorus smelting slag. By modifying the slag composition and physical state, combined with adjustments to the alkalinity of the metallurgical slag and the cooling rate, the ratio of amorphous to crystalline phases in the slag is adjusted, enabling the adjusted slag to simultaneously possess the properties of nutrient slow-release and moisture retention. Figure 1 As shown, the specific steps include:

[0044] S1. Based on the composition of high-phosphorus smelting slag, the additives are mixed evenly with the high-phosphorus smelting slag, and the binary basicity of the final slag is adjusted to obtain a uniformly mixed metallurgical slag.

[0045] In a preferred embodiment, the high-phosphorus smelting slag in S1 is the smelting slag produced by the rapid reduction smelting process, the ironmaking and steelmaking slag produced during the long-process smelting process, or the high-phosphorus slag produced by various industries.

[0046] In a preferred embodiment, the rapid reduction melting process specifically includes:

[0047] High-phosphorus iron-containing resources, carburizing agent, flux, and binder are added and mixed in a predetermined ratio. After wetting with an appropriate amount of water and mixing again, the mixture is pressed into lumps with a certain compressive strength. The carburizing agent is anthracite or coke powder, with a fixed carbon content of about 80%, an ash content of less than 15%, and a particle size of less than 1 mm. The maximum basicity of the lumps is 2.0. The carburizing agent is 0-2% of the weight of the iron-containing material. The flux is limestone and industrial-grade sodium carbonate, with the industrial-grade sodium carbonate content being 0-3% of the weight of the iron-containing material.

[0048] After drying, the lumps are loaded into a vertical shaft furnace for gas-based reduction. The reducing gas comes from natural gas and the tail gas of the reduction furnace reforming to produce metallized lumps.

[0049] The metallized lumps are discharged and directly charged into a melting furnace for rapid melting and separation using methods such as natural gas combustion, plasma torch, or electric arc heating. After water quenching and magnetic separation, solid granular pig iron and glass slag are produced. In the gas-based melting furnace, natural gas burners are used to rapidly heat the metallized lumps, achieving rapid slag-iron separation. The molten pig iron or semi-steel and slag after melting and separation are quickly discharged into a water tank for water quenching, thus obtaining the molten slag.

[0050] Here, compared to natural gas combustion heating, plasma torch or electric arc heating can achieve a much faster heating effect. Using plasma torch or electric arc heating, the heating temperature can reach 1450℃-1800℃, and the melting time can be further shortened to 5-8 minutes. The higher heating temperature significantly improves the yield of metallic iron and the dephosphorization rate during the smelting process. Furthermore, based on the glass phase ratio and nutrient element content in the conditioning agent obtained from this slag, it is more conducive to enhancing its water retention and slow-release nutrient effects.

[0051] When using plasma heating, the specific parameters are shown in Table 1 below:

[0052] Table 1. Plasma melting process parameters

[0053]

[0054] In a preferred embodiment, the high-phosphorus smelting slag is in a solid or high-temperature molten state.

[0055] In a preferred embodiment, the high-phosphorus smelting slag contains 1%-10% phosphorus and 5%-50% FeO. Furthermore, the slag does not contain heavy metals that could potentially pollute the soil.

[0056] In a preferred embodiment, the suitable binary basicity of the endpoint slag in S1 is 1.0-2.0.

[0057] Here, binary alkalinity refers to the mass ratio of the main alkaline oxide CaO to the main acidic oxide SiO2 in the slag. This ratio represents some basic properties of the slag, such as fluidity and the interaction forces between elements in the slag. In the technical solution of this application, an excessively high proportion of free CaO in the slag will lead to a decrease in slag activity and an increase in the slag's melting point, resulting in the formation of more crystalline phases during cooling and affecting the element leaching effect of the soil conditioner; while an excessively low alkalinity will reduce the phosphorus capacity of the slag, thereby affecting the available phosphorus content in the soil conditioner and reducing the release effect of phosphorus.

[0058] like Figure 3 As shown, when the slag basicity is 0.8, the slag citrate solubility is 20.67%, which is relatively low. This results in insufficient phosphorus release from the soil conditioner, failing to achieve the effect of slow-release nutrients. When the slag basicity is greater than 2, although the citrate-soluble phosphorus content is high, the excessive free CaO content in the slag makes the slag phase difficult to dissolve. Furthermore, the large amount of free CaO leads to an excessive crystalline phase content in the water-quenched slag, fixing a large amount of nutrients. Although the citrate solubility increases, the nutrient release rate decreases, making it difficult to achieve the effect of a soil conditioner. When the slag basicity is higher than 1.7, the citrate solubility is high while ensuring a suitable nutrient release rate. Therefore, the suitable basicity range for this slag phase is 1.0-2.0, preferably 1.7-2.0.

[0059] Furthermore, the additive in S1 is an alkalinity regulator.

[0060] Furthermore, the alkalinity regulator in S1 is quartz (SiO2), quicklime (CaO), or limestone (CaCO3).

[0061] S2. The metallurgical slag is placed in a heating furnace and heated until all the substances melt into a liquid state. After heat preservation, the slag is rapidly cooled to room temperature.

[0062] In a preferred embodiment, the heating temperature in step S2 is 1500℃-1800℃ to ensure that the solid slag and additives are completely melted; the holding time after complete melting is 30min-1.5h.

[0063] Here, the melting points of individual SiO2 or CaO are very high, reaching over 2000℃. Only when the proportions of the components in the slag are appropriate, forming low-melting-point compounds (such as Ca2SiO2), can the melting point of the slag be lowered and its fluidity improved. At low heating temperatures, the components in the slag do not melt sufficiently, while high heating temperatures lead to energy waste. More importantly, if the alkalinity is unsuitable during the slag melting process, or the heating temperature is insufficient to completely melt the slag phase, the distribution of elements and crystal structure in the soil conditioner will be uneven. This increases the difficulty of the subsequent fine grinding process and makes it difficult for nutrients to be released during subsequent use of the soil conditioner.

[0064] In a preferred embodiment, the rapid cooling in S2 is air cooling, atomized cooling, or water cooling.

[0065] In a preferred embodiment, the cooling time to room temperature in step S2 is 5s-30s, in order to control the proportion of amorphous phase in the slag to be greater than 30%. In a preferred embodiment, the cooling time to room temperature in step S2 is 5s.

[0066] Here, the atoms or molecules inside a crystal are arranged periodically, while amorphous solids are characterized by short-range order but long-range disorder. Crystals are much more stable than amorphous solids; therefore, by modifying the ratio of crystals to amorphous solids in soil conditioners, the leaching rate of nutrients in the conditioner can be indirectly controlled.

[0067] S3. After the slag is cooled to room temperature, it is dried and finely ground to obtain a soil conditioner.

[0068] In a preferred embodiment, step S3 further includes spreading the soil conditioner evenly on the soil surface and mixing the soil conditioner evenly with the soil by tilling.

[0069] In a preferred embodiment, the finely ground soil conditioner in S3 has a particle size between 50 mesh and 300 mesh.

[0070] Here, the particle size setting fully considers the particle size composition of soil particles. If the particle size is too fine, the soil density will be too high, which is not conducive to water infiltration; while if the conditioner particles are too large, the particle specific surface area will be small, the leaching of elements will be hindered, and the water will be lost too quickly.

[0071] In a preferred embodiment, in step S3, the soil conditioner is uniformly dispersed 2-15 cm below the soil surface.

[0072] In a preferred embodiment, in step S3, the amount of soil conditioner used is 100-2000 kg / mu.

[0073] The present invention also provides a soil conditioner prepared by modifying high-phosphorus smelting slag, wherein the soil conditioner is prepared according to the method described above.

[0074] Example 1

[0075] The raw material conditions are: high-phosphorus smelting slag obtained by smelting high-phosphorus iron ore in Algeria in the laboratory; the project is the applicant's project in Algeria.

[0076] The Jebilit iron ore mine, located in Tindouf Province in southwestern Algeria, is a giant iron ore deposit with reserves of up to 1.6 billion tons and an average iron content of 53%. However, the mine's iron ore has a high phosphorus content, and due to limitations in ore beneficiation and dephosphorization technology, it has only recently begun joint development with relevant Chinese companies.

[0077] The slag obtained through rapid reduction smelting process contains a large number of valuable nutrients. In order to utilize this industrial waste slag and jointly address the local desertification soil problem, a soil conditioner with both water retention and slow nutrient release properties has been developed using this metallurgical slag.

[0078] The main components of high-phosphorus metallurgical slag are FeO (10%), P (5%), MgO (5%), Al2O3 (10.5%), CaO and SiO2 (approximately 30%), and C (2%).

[0079] 100g of high-phosphorus metallurgical slag as shown in the composition was selected. Based on the CaO and SiO2 content, to achieve a basicity of 1.7 in the remelted high-phosphorus slag, 21g of quicklime reagent (CaO) was added. The mixed reagent was initially ground in a crucible to ensure complete dissolution of the slag phase and quicklime additive during heating. The ground mixture was placed in a molybdenum crucible with a graphite sleeve and then placed in a muffle furnace. The heating rate of the muffle furnace was adjusted to 10℃ / min, the final temperature was 1600℃, and the holding time was 1 hour, using nitrogen as a protective gas. After heating, the molten slag was quickly removed from the muffle furnace and rapidly poured into cooling water. The remelted slag, cooled to room temperature, was removed, dried, and finely ground to 200 mesh to obtain the prepared soil conditioner. Figure 2 As shown. The citrate content was determined to be 55.78% according to GB / T8573-2017 standard. 100g of the prepared soil conditioner was mixed with 1000g of poor sandy soil, ensuring the conditioner was evenly distributed 2-5cm below the surface of the soil in the pot. A blank control group with 1100g of the same sandy soil was also prepared. Both groups of pots were thoroughly watered and placed outdoors. After 10 days, the soil in the blank control group was completely dry, while the soil in the pot with the soil conditioner still felt moist beneath the surface, indicating excellent water retention (e.g., ...). Figure 4As shown, the left side represents the group with added soil water-retaining agent, and the right side represents the group without added agent. Furthermore, subsequent experiments verified that the better nutrient element penetration resulted in a significant advantage in crop growth compared to the blank control group.

[0080] In summary, this invention discloses a method for preparing a soil conditioner using high-phosphorus metallurgical slag modification. The method includes: adding and mixing phosphorus-containing metallurgical slag and an alkalinity regulator in a predetermined ratio; melting and cooling the molten liquid slag at high temperature; and then water-quenching and finely grinding the molten slag to produce a glassy inorganic water-retaining agent with a porous structure. This invention features a simple preparation process, strong raw material adaptability, and low cost. The resulting soil conditioner has a porous surface, exhibits very high water adsorption capacity, and can slowly release nutrients such as phosphorus and calcium into the soil, promoting plant growth. It is a high-quality material integrating soil water retention and slow-release fertilizer functions, and is of great significance in the comprehensive utilization of metallurgical slag and soil improvement.

[0081] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for preparing a soil conditioner by modifying high-phosphorus smelting slag, characterized in that, The soil conditioner has both water retention and nutrient release functions, and the citrate-soluble phosphorus content of the soil conditioner is 20-80%. The method includes: S1. Based on the composition of the high-phosphorus smelting slag, the additive is uniformly mixed with the high-phosphorus smelting slag, and the binary basicity of the final slag is adjusted to 1.0-2.0, wherein the binary basicity refers to the mass ratio of CaO to SiO2 in the slag. Then, grinding is performed to obtain a uniformly mixed metallurgical slag; wherein the phosphorus content in the high-phosphorus smelting slag is 1%-10%, and the FeO content is 5%-50%. The high-phosphorus smelting slag is the smelting slag produced by the rapid reduction smelting process; The rapid reduction melting process specifically includes: High-phosphorus iron-containing resources, carburizing agent, flux, and binder are added and mixed in a predetermined ratio. The mixture is then moistened with an appropriate amount of water, mixed again, and pressed into lumps with a certain compressive strength. The carburizing agent is anthracite or coke powder, with a fixed carbon content of approximately 80%, an ash content of less than 15%, and a particle size of less than 1 mm. The maximum basicity of the lumps is 2.

0. The carburizing agent is 0-2% of the weight of the iron-containing material, and the flux is limestone and industrial-grade sodium carbonate, with the industrial-grade sodium carbonate accounting for 0-3% of the weight of the iron-containing material. After drying, the lumps are loaded into a vertical shaft furnace for gas-based reduction. The reducing gas comes from natural gas and the tail gas of the reduction furnace reforming to produce metallized lumps. The metallized lumps are discharged and directly charged into the melting furnace for rapid melting using natural gas combustion. After water quenching and magnetic separation, solid granular pig iron and glass slag are produced. The gas-based melting furnace uses natural gas burners to rapidly heat the metallized lumps, achieving rapid slag-iron separation. The molten pig iron or semi-steel and slag after melting are quickly discharged into a water tank for water quenching, thus obtaining the melted slag. S2. The metallurgical slag is placed in a heating furnace and heated to a temperature of 1500℃-1800℃. After all the substances have melted into a liquid state and the temperature is maintained for 30 minutes to 1.5 hours, the slag is rapidly cooled to room temperature, wherein the rapid cooling is water cooling; the cooling time to room temperature is 5 seconds to 30 seconds, in order to control the proportion of amorphous phase in the slag to be greater than 30%. S3. The slag obtained in S2 is dried and finely ground to obtain a soil conditioner.

2. The method according to claim 1, characterized in that, In S1, the high-phosphorus smelting slag is in a solid or high-temperature molten state.

3. The method according to claim 1, characterized in that, The suitable binary basicity of the endpoint residue in S1 is 1.7-2.

0.

4. The method according to claim 1, characterized in that, The additive in S1 is an alkalinity regulator; The alkalinity regulator is quartz (SiO2), quicklime (CaO), or limestone (CaCO3).

5. The method according to claim 1, characterized in that, The finely ground soil conditioner in S3 has a particle size between 50 mesh and 300 mesh and is evenly dispersed 2-15 cm below the soil surface. The dosage of the soil conditioner is 100-2000 kg / mu.

6. A soil conditioner prepared by modifying high-phosphorus smelting slag, wherein, The soil conditioner is prepared using the method described in any one of claims 1 to 5.

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