Soil ecological restoration matrix with ardealite as main raw material as well as preparation and application of soil ecological restoration matrix

Abstract

The invention relates to a soil ecological restoration matrix with ardealite as a main raw material, and preparation and application thereof, and belongs to the field of solid waste recycling. Comprising phosphogypsum, carbide slag, fly ash, an organic fertilizer and a water-retaining agent in a mass part ratio of 100: (0.5-3): (1-5): (5-10): (0.01-0.02). The germination rate of ryegrass and festuca arundinacea in the medium is 70% or above, the average plant height in 30 days is 15 cm or above, the ryegrass and festuca arundinacea grow well, meanwhile, the fixation rate of the medium to water-soluble fluorine in phosphogypsum can reach 90% or above, and the content of heavy metal in the medium and the content of heavy metal in medium lixivium both meet the national standard. The proportion of the ardealite in the substrate is up to 85% or above, and large-scale efficient utilization of ardealite resource is achieved. The material can be used as a surface soil substitute material for mine ecological restoration, desertification ecological restoration and landscaping while promoting resource recycling.

Description

Technical Field

[0001] The present invention belongs to the field of solid waste resource utilization, and particularly relates to a soil ecological restoration matrix using phosphogypsum as a main raw material, as well as its preparation and application. Background Art

[0002] Phosphogypsum is an industrial solid waste generated during the wet-process phosphoric acid production process. Its primary component is CaSO₄·2H₂O. Currently, my country's phosphogypsum stockpile exceeds 800 million tons, increasing by 50 million tons annually. However, the comprehensive utilization rate of phosphogypsum is less than 50%. Phosphogypsum can be used as a construction material, such as cement retarders and building plaster, as well as in chemical products such as ammonium sulfate and high-purity calcium carbonate. However, due to its high cost and the presence of impurities such as phosphorus, fluorine, and small amounts of heavy metals, its comprehensive utilization rate is low.

[0003] Most unused phosphogypsum is stockpiled, which not only takes up a large amount of land but also poses a risk of leakage of pollutants such as phosphorus, fluorine, and heavy metals contained in the phosphogypsum, impacting surface and groundwater. Phosphogypsum is rich in phosphorus, as well as calcium, magnesium, and phosphorus, which are essential for plant growth. If phosphogypsum is combined with other materials to fix the fluorine and heavy metals in the phosphogypsum and create a soil remediation matrix, this not only solves the problem of large-scale phosphogypsum stockpiling but also provides a new method for ecological restoration in degraded areas.

[0004] Patent publication number CN117837468A discloses a method for modifying a phosphogypsum plantation matrix using agricultural solid waste. The matrix is ​​prepared by mixing 75% phosphogypsum, 5% biochar, 5% cow dung, and 15% fungus residue. This method restructures the microbial community structure within the phosphogypsum matrix, allowing lush ryegrass growth. However, the ryegrass germination rate in this matrix is ​​only 62.67%, and the high organic matter content makes it relatively expensive. This method achieves a fluorine removal rate of 84.87% and a phosphate removal rate of 99.68% in the matrix leachate. Sb, Cr, Pb, Cu, Zn, As, and Mn removal rates are all above 90%. However, this method does not address the nutrient content of the matrix, and the germination rate is low.

[0005] The patent with publication number CN116897800A discloses a method for preparing landscaping soil in a large-scale and fully soilless manner using red mud and phosphogypsum. The formula is 49.4% red mud, 32.9% phosphogypsum, 16.5% distiller's grains, 1.1% sodium bentonite, 0.02% organic granulating agent, 0.075% distiller's yeast and 0.005% microbial agent. After adding water and mixing, a matrix can be obtained. Although this matrix can meet the conditions for plant growth, the amount of phosphogypsum used is small, and red mud and sodium bentonite may cause salinization of the matrix, and the performance of the matrix may decrease with long-term use. At the same time, the invention does not pay attention to the potential pollutants such as fluorine and heavy metals in the matrix. Summary of the Invention

[0006] The object of the present invention is to provide a method for preparing a soil ecological restoration matrix with phosphogypsum as the main raw material, using phosphogypsum as the main raw material, carbide slag and fly ash as modifying materials, and applying organic fertilizer and water-retaining agent to improve the performance of the matrix. By planting green plants such as ryegrass and tall fescue, rapid restoration of degraded soils such as mining areas and desertification can be achieved, achieving a greening effect. By utilizing the synergistic effect of carbide slag and fly ash, fluorine and heavy metals in phosphogypsum can be effectively fixed. The phosphogypsum soil ecological restoration matrix of the present invention has a simple formula, good effect, can achieve coordinated management of multi-source solid waste, and has good application prospects.

[0007] According to a first aspect of the present invention, a soil ecological restoration matrix with phosphogypsum as the main raw material is provided, comprising phosphogypsum, carbide slag, fly ash, organic fertilizer and water-retaining agent, wherein the mass ratio of the phosphogypsum, carbide slag, fly ash, organic fertilizer and water-retaining agent is 100: (0.5-3): (1-5): (5-10): (0.01-0.02).

[0008] Preferably, the organic fertilizer is livestock and poultry manure organic fertilizer, compost product or biomass carbon.

[0009] Preferably, the water-retaining agent is polyacrylamide, potassium polyacrylate, water-absorbing resin or water-absorbing gel.

[0010] According to another aspect of the present invention, a method for preparing a soil ecological restoration matrix using phosphogypsum as a main raw material is provided. The method comprises drying phosphogypsum, fly ash, and carbide slag, then mixing the phosphogypsum, carbide slag, fly ash, organic fertilizer, and water-retaining agent in a mass ratio of 100: (0.5-3): (1-5): (5-10): (0.01-0.02). Water is then added, wherein the mass of the water is 15%-30% of the total mass of the phosphogypsum, carbide slag, fly ash, organic fertilizer, and water-retaining agent. After thorough mixing, the mixture is aged for 3-5 days to obtain the soil ecological restoration matrix.

[0011] Preferably, the organic fertilizer is livestock and poultry manure organic fertilizer, compost or biomass carbon.

[0012] Preferably, the water-retaining agent is polyacrylamide, potassium polyacrylate or a water-absorbing resin.

[0013] Preferably, the drying temperature of the phosphogypsum is 40-60° C., and the drying time is 24-48 hours.

[0014] Preferably, the drying temperature of fly ash and carbide slag is 80-105° C., and the drying time is 12-24 h.

[0015] According to another aspect of the present invention, there is provided an application of a soil ecological restoration matrix using phosphogypsum as a main raw material in mine ecological restoration or desertification area ecological restoration.

[0016] According to another aspect of the present invention, there is provided an application of a soil ecological restoration matrix using phosphogypsum as a main raw material as a topsoil substitute material for landscaping.

[0017] In general, the above technical solutions conceived by the present invention have the following technical advantages compared with the existing technology: (1) This invention prepares a soil ecological restoration matrix using phosphogypsum as the main raw material, providing a new method for the comprehensive utilization of phosphogypsum. Carbide slag and fly ash, both industrial solid wastes, are used to adjust the acidity of the phosphogypsum while simultaneously controlling pollutants such as fluorine and heavy metals, thereby achieving synergistic management of solid waste. Phosphogypsum accounts for over 85% of the matrix, resolving the issue of large phosphogypsum stockpiles. This method has the advantages of low cost and a wide range of material sources.

[0018] (2) The main component of the phosphogypsum in the present invention is CaSO4·2H2O, which has a pH of about 2-4 and is weakly acidic. It also contains soluble fluorine and a small amount of heavy metals and other pollutants. Direct use may pose potential ecological hazards. After adding calcium carbide slag, whose main component is Ca(OH)2, the acidity of the phosphogypsum can be neutralized, and the soluble fluorine in the phosphogypsum will be converted into precipitated CaF2. The main components of fly ash are mullite and quartz, which has a high specific surface area and contains a large amount of active silicon oxide and aluminum oxide. It has good adsorption capacity and can absorb some soluble fluorine and heavy metals. Fly ash is also a commonly used soil conditioner that can provide plants with medium-sized elements such as Si and Mg. The present invention uses calcium carbide slag and fly ash together to adjust the pH of the phosphogypsum to neutral while fixing the soluble fluorine and heavy metals contained in the phosphogypsum.

[0019] (3) Organic fertilizer and water-retaining agent are used in the present invention. Phosphogypsum contains relatively few organic nutrients. Adding organic fertilizer can provide organic nutrients to the matrix, improve the matrix structure, and enhance the matrix's fertilizer retention performance. Adding water-retaining agent can improve the matrix's water retention performance. The water-retaining agent can absorb more than 200 times its own weight of water and slowly release water when the matrix is ​​dehydrated, thus giving the matrix a certain degree of drought resistance.

[0020] (4) The soil ecological modification matrix of the present invention can fix water-soluble fluorine in phosphogypsum at a rate of over 90%, and the heavy metal content in the matrix and the matrix leachate meets national standards. The present invention uses industrial waste phosphogypsum as an ecological restoration matrix material to solve the problems of phosphogypsum accumulation and environmental pollution. At the same time, it uses industrial solid waste such as calcium carbide slag and fly ash to achieve the goal of "waste treatment with waste". In addition, the proportion of phosphogypsum in the matrix is ​​as high as over 85%, realizing large-scale and efficient resource utilization of phosphogypsum. While promoting resource recycling, it provides a new and economical solution for scenarios such as mine ecological restoration, desertification ecological restoration, and landscaping in soil-deficient areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a flow chart of the matrix compounding.

[0022] Figure 2 This is a specific growth diagram of ryegrass in Example 1 of the present invention.

[0023] Figure 3 This is a diagram showing the change in matrix porosity in Example 1 of the present invention.

[0024] Figure 4 The nutrient content of the substrate changes in Example 1 of the present invention.

[0025] Figure 5 This is a specific growth diagram of tall fescue in Example 2 of the present invention.

[0026] Figure 6 This is a specific growth diagram of tall fescue in Example 3 of the present invention.

[0027] Figure 7 This is a specific growth diagram of tall fescue in Example 4 of the present invention.

[0028] Figure 8 This is a scene picture of the mixed grass seeds being sown in Example 5 of the present invention.

[0029] Figure 9 This is a field photo of the mixed grass seeds in Example 5 of the present invention one month after being sown.

[0030] Figure 10 This is a field photo of the mixed grass seeds in Example 5 of the present invention two months after sowing. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0032] The present invention discloses a soil ecological restoration matrix using phosphogypsum as a main raw material. The matrix comprises phosphogypsum, carbide slag, fly ash, organic fertilizer and a water-retaining agent, wherein the mass ratio of the phosphogypsum, carbide slag, fly ash, organic fertilizer and the water-retaining agent is 100: (0.5-3): (1-5): (5-10): (0.01-0.02).

[0033] The method for preparing a soil ecological restoration matrix using phosphogypsum as a raw material provided by the present invention comprises the following steps: (1) Dry the phosphogypsum in an oven at 40-60℃ for 24-48 hours, and grind the dried phosphogypsum through a 10-100 mesh sieve for later use.

[0034] (2) Dry the fly ash and carbide slag in an oven at 80-105℃ for 12-24 hours. After drying, grind them through a 10-100 mesh sieve for later use.

[0035] (3) Take 100 parts of phosphogypsum, 0.5-3 parts of carbide slag, 1-5 parts of fly ash, 5-10 parts of organic fertilizer, and 0.01-0.02 parts of water retaining agent, mix them evenly, add ultrapure water (15-30% by weight of the total weight of the matrix), and stir evenly to obtain the matrix of the present invention.

[0036] In some embodiments, the phosphogypsum is old gypsum that has been stored for more than one year.

[0037] Figure 1 The present invention is a flow chart of the matrix compounding.

[0038] The following are specific embodiments Example 1 A method for preparing a soil ecological restoration matrix using phosphogypsum as a raw material comprises the following steps: (1) Material preparation: Phosphogypsum was obtained from a phosphogypsum storage yard in Yichang City, carbide slag was obtained from a chemical plant in Zhengzhou City, fly ash was obtained from a power plant in Wenzhou City, livestock and poultry manure organic fertilizer was obtained from a nearby farm, and potassium polyacrylate was purchased from a reagent company. Phosphogypsum, carbide slag, and fly ash were dried, ground, and passed through a 10-mesh sieve for later use.

[0039] (2) Weigh 100 g of phosphogypsum, 0.5 g of carbide slag, 1 g of fly ash, 5 g of organic fertilizer, and 0.015 g of potassium polyacrylate (as a water-retaining agent) in a small flower pot, mix well, and then add about 26 g of water and stir evenly.

[0040] (3) Soak ryegrass and tall fescue seeds in water overnight. Thirty seeds with full grains were selected for potting experiments. After sowing, the substrate was placed in a plant incubator with the following parameters: 16 hours of daylight, 15,000 Lx, and a temperature of 28°C; 8 hours of nightlight, no light, and a temperature of 20°C. Water was applied once a day, morning and evening, ensuring a consistent daily watering amount. The substrate leachate produced after watering was collected and measured 30 days later.

[0041] (4) The germination rate of ryegrass and tall fescue was measured 7 days after sowing, and the plant height was measured 30 days after sowing. The pH, heavy metals, and fluoride of the substrate and leachate were also measured. After the substrate was digested, the total amount of heavy metals was measured using ICP-OES. Mercury was measured using cold atomic fluorescence spectrometry. The total fluoride and water-soluble fluoride content in the substrate were measured using JC / T 2073-2011 "Determination of phosphorus and fluoride in phosphogypsum". The fluoride concentration in the leachate was measured using an ion-selective electrode method, and the heavy metal concentration in the leachate was measured using ICP-OES.

[0042] (5) The germination rates of tall fescue and ryegrass were 83.33% and 86.67%, respectively. The average plant heights of tall fescue and ryegrass after 30 days were 14.36 cm and 16.21 cm, respectively. Figure 2 Detailed growth diagram of ryegrass in this embodiment.

[0043] Figure 3 This is a graph showing the change in matrix porosity in Example 1 of the present invention. Figure 6 It can be seen that after phosphogypsum is compounded into the matrix, the total porosity increases, the non-capillary porosity of the matrix increases, and the air permeability increases.

[0044] Figure 4 is the change of nutrient content of the substrate in Example 1 of the present invention. Figure 7 It can be seen that after adding organic fertilizer, nutrients such as organic matter and nitrogen that are lacking in phosphogypsum are increased, providing nutritional conditions for plant growth, and the content of organic matter and hydrolyzable nitrogen can meet the CJ / T 340-2016 "Greening Planting Soil" standard.

[0045] (6) As shown in Table 1, the matrix was compared with GB 15618-2018 "Soil Environmental Quality Agricultural Land Soil Risk Control Standard", and the heavy metal content was within the standard range. As shown in Table 2, the matrix leachate was compared with the first-level standard in GB 8978-1996 "Integrated Wastewater Discharge Standard", and the pH, heavy metals, and fluorine all met the standard.

[0046] Example 2 (1) Material preparation: Phosphogypsum was obtained from a phosphogypsum storage yard in Yichang City, carbide slag was obtained from a chemical plant in Zhengzhou City, fly ash was obtained from a power plant in Wenzhou City, livestock and poultry manure organic fertilizer was obtained from a nearby farm, and potassium polyacrylate was purchased from a reagent company. Phosphogypsum, carbide slag, and fly ash were dried, ground, and passed through a 10-mesh sieve for later use.

[0047] (2) Weigh 100 g of phosphogypsum, 1.5 g of carbide slag, 2 g of fly ash, 10 g of organic fertilizer, and 0.02 g of potassium polyacrylate into a flower pot, mix well, add about 16 g of water, and stir evenly.

[0048] (3) Soak ryegrass and tall fescue seeds in water overnight. 100 seeds with full grains were selected for potting experiments. After sowing, the substrate was placed in a plant incubator with the following parameters: 16 hours of daytime, 15,000 Lx of light, 28°C temperature, and 8 hours of nighttime, no light, and 20°C temperature. Water was applied once a day, morning and evening, ensuring consistent daily watering. The substrate leachate produced after watering was collected and measured 30 days later.

[0049] (4) The germination rate of ryegrass and tall fescue was measured 7 days after sowing, and the plant height was measured 30 days after sowing. The pH, heavy metals, and fluoride of the substrate and leachate were also measured. After the substrate was digested, the total amount of heavy metals was measured using ICP-OES. Mercury was measured using cold atomic fluorescence spectrometry. The total fluoride and water-soluble fluoride content in the substrate were measured using JC / T 2073-2011 "Determination of phosphorus and fluoride in phosphogypsum". The fluoride concentration in the leachate was measured using an ion-selective electrode method, and the heavy metal concentration in the leachate was measured using ICP-OES.

[0050] (5) The germination rates of tall fescue and ryegrass were 84.00% and 85.00%, respectively. The average plant heights of tall fescue and ryegrass after 30 days were 15.34 cm and 15.68 cm, respectively. Figure 5 Detailed growth diagram of tall fescue in this embodiment.

[0051] (6) As shown in Table 1, the matrix was compared with GB 15618-2018 "Soil Environmental Quality Agricultural Land Soil Risk Control Standard", and the heavy metal content was within the standard range. As shown in Table 2, the matrix leachate was compared with the first-level standard in GB 8978-1996 "Integrated Wastewater Discharge Standard", and the pH, heavy metals, and fluorine all met the standard.

[0052] Example 3 Effects of different material dosages on the performance of phosphogypsum soil ecological remediation matrix (1) Material preparation: Phosphogypsum was obtained from a phosphogypsum storage yard in Yichang City, carbide slag was obtained from a chemical plant in Zhengzhou City, fly ash was obtained from a power plant in Wenzhou City, livestock and poultry manure organic fertilizer was obtained from a nearby farm, and polyacrylamide was purchased from a reagent company. Phosphogypsum, carbide slag, and fly ash were dried, ground, and passed through a 10-mesh sieve for later use.

[0053] (2) Weigh 100 g of phosphogypsum, 1 g of carbide slag, 1 g of fly ash, 10 g of organic fertilizer, and 0.02 g of potassium polyacrylate into a flower pot, mix well, add about 25 g of water, and stir evenly.

[0054] (3) Soak ryegrass and tall fescue seeds in water overnight. Fifty seeds with full grains were selected for potting experiments. After sowing, the substrate was placed in a plant incubator with the following parameters: 16 hours of daylight, 15,000 Lx, and a temperature of 28°C; 8 hours of nightlight, no light, and a temperature of 20°C. Water was applied once a day, morning and evening, ensuring a consistent daily watering amount. The substrate leachate produced after watering was collected and measured 30 days later.

[0055] (4) The germination rate of ryegrass and tall fescue was measured 7 days after sowing, and the plant height was measured 30 days after sowing. The pH, heavy metals, and fluoride of the substrate and leachate were also measured. After the substrate was digested, the total amount of heavy metals was measured using ICP-OES. Mercury was measured using cold atomic fluorescence spectrometry. The total fluoride and water-soluble fluoride content in the substrate were measured using JC / T 2073-2011 "Determination of phosphorus and fluoride in phosphogypsum". The fluoride concentration in the leachate was measured using an ion-selective electrode method, and the heavy metal concentration in the leachate was measured using ICP-OES.

[0056] (5) The germination rates of tall fescue and ryegrass were 82.00% and 86.00%, respectively. The average plant heights of tall fescue and ryegrass after 30 days were 16.12 cm and 15.78 cm, respectively. Figure 6 Detailed growth diagram of tall fescue in this embodiment.

[0057] (6) As shown in Table 1, the matrix was compared with GB 15618-2018 "Soil Environmental Quality Agricultural Land Soil Risk Control Standard", and the heavy metal content was within the standard range. As shown in Table 2, the matrix leachate was compared with the first-level standard in GB 8978-1996 "Integrated Wastewater Discharge Standard", and the pH, heavy metals, and fluorine all met the standard.

[0058] Example 4 (1) Material preparation: Phosphogypsum was obtained from a phosphogypsum storage yard in Xiaogan City, carbide slag was obtained from a chemical plant in Yichang City, fly ash was obtained from a power plant in Lanxi City, livestock and poultry manure organic fertilizer was obtained from a farm in Yichang City, and potassium polyacrylate was purchased from a reagent company. Phosphogypsum, carbide slag, and fly ash were dried, ground, and passed through a 10-mesh sieve for later use.

[0059] (2) Weigh 500 g of phosphogypsum, 7 g of carbide slag, 6 g of fly ash, 50 g of organic fertilizer, and 0.1 g of potassium polyacrylate into a flower pot, mix well, add about 100 g of water, and stir evenly.

[0060] (3) Soak tall fescue seeds in water overnight. Select 100 seeds with full grains for potting experiments. After sowing, place the substrate in a plant incubator with the following parameters: 16 hours of daylight, 15,000 Lx, 28°C temperature, 8 hours of darkness, no light, 20°C temperature. Water the plants once a day, morning and evening, ensuring consistent watering. Collect the substrate leachate produced after watering and measure it 30 days later.

[0061] (4) The germination rate of ryegrass and tall fescue was measured 7 days after sowing, and the plant height was measured 30 days after sowing. The pH, heavy metals, and fluoride of the substrate and leachate were also measured. After the substrate was digested, the total amount of heavy metals was measured using ICP-OES. Mercury was measured using cold atomic fluorescence spectrometry. The total fluoride and water-soluble fluoride content in the substrate were measured using JC / T 2073-2011 "Determination of phosphorus and fluoride in phosphogypsum". The fluoride concentration in the leachate was measured using an ion-selective electrode method, and the heavy metal concentration in the leachate was measured using ICP-OES.

[0062] (5) The germination rate of tall fescue was 81.00%, and the average plant height of tall fescue was 17.28 cm after 30 days. Figure 7 Detailed growth diagram of tall fescue in this embodiment.

[0063] (6) As shown in Table 1, the matrix was compared with GB 15618-2018 "Soil Environmental Quality Agricultural Land Soil Risk Control Standard", and the heavy metal content was within the standard range. As shown in Table 2, the matrix leachate was compared with the first-level standard in GB 8978-1996 "Integrated Wastewater Discharge Standard", and the pH, heavy metals, and fluorine all met the standard.

[0064] Table 1 Matrix pH and contaminant data (units except pH: mg / kg) Note: GB 15618-2018 “Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard” Table 2 Matrix leachate pH and pollutant data (units except pH: mg / L) Note: GB 8978-1996 Integrated Wastewater Discharge Standard Example 5 To further verify the feasibility of this matrix, a field experiment was conducted. The on-site formula was 100 parts phosphogypsum, 1.5 parts carbide slag, 5 parts fly ash, 5 parts organic fertilizer, and a small amount of potassium polyacrylate (0.01 part) as a water-retaining agent.

[0065] A closed phosphogypsum depot in Yichang City was selected for ecological restoration. While the typical restoration approach involves filming for anti-seepage protection and then applying 50 cm of imported soil, this approach employed 20 cm of imported soil followed by 30 cm of substrate. A mixed grass seed system, including ryegrass, tall fescue, and zinnia seeds, was subsequently sown, resulting in excellent plant growth. Four leachate collection devices (A, B, C, and D) were installed on site to collect leachate after rainy days. As shown in Table 3, the leachate met the GB 8978-1996 Integrated Wastewater Discharge Standard for fluoride and heavy metals. Figure 8 、 Figure 9 、 Figure 10 The on-site pictures are taken right after sowing, one month after sowing, and two months after sowing. It can be seen that the soil ecological restoration matrix of the present invention enables the mixed grass seeds to grow well during on-site restoration.

[0066] Table 3 On-site leachate pH and pollutant data (units except pH: mg / L) The above embodiments are merely examples. In actual situations, the amount of material added can be appropriately changed according to the actual pH of the phosphogypsum. When the pH of the phosphogypsum is low or the water-soluble fluorine content is high, the amount of material added can also be appropriately increased.

[0067] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A soil ecological restoration matrix with phosphogypsum as the main raw material, characterized in that: The invention comprises phosphogypsum, carbide slag, fly ash, organic fertilizer and water retaining agent, wherein the mass ratio of the phosphogypsum, carbide slag, fly ash, organic fertilizer and water retaining agent is 100: (0.5-3): (1-5): (5-10): (0.01-0.02).

2. The soil ecological restoration matrix with phosphogypsum as the main raw material according to claim 1, characterized in that The organic fertilizer is livestock and poultry manure organic fertilizer, compost product or biomass carbon.

3. The soil ecological restoration matrix with phosphogypsum as the main raw material according to claim 1, characterized in that The water-retaining agent is polyacrylamide, potassium polyacrylate, water-absorbing resin or water-absorbing gel.

4. The method for preparing a soil ecological restoration matrix using phosphogypsum as a main raw material according to any one of claims 1 to 3, characterized in that: The phosphogypsum, fly ash and carbide slag are dried, and then the phosphogypsum, carbide slag, fly ash, organic fertilizer and water retaining agent are mixed, wherein the mass ratio of the phosphogypsum, carbide slag, fly ash, organic fertilizer and water retaining agent is 100: (0.5-3): (1-5): (5-10): (0.01-0.02); then water is added, and the mass of the water is 15%-30% of the total mass of the five components, namely, the phosphogypsum, carbide slag, fly ash, organic fertilizer and water retaining agent. After fully mixing, the soil ecological restoration matrix is ​​obtained after aging for 3-5 days.

5. The method for preparing a soil ecological restoration matrix using phosphogypsum as a main raw material according to claim 4, wherein: The organic fertilizer is livestock and poultry manure organic fertilizer, compost or biomass carbon.

6. The method for preparing a soil ecological restoration matrix using phosphogypsum as a main raw material according to claim 4, wherein: The water-retaining agent is polyacrylamide, potassium polyacrylate or water-absorbing resin.

7. The method for preparing a soil ecological restoration matrix using phosphogypsum as a main raw material according to claim 4, wherein: The drying temperature of the phosphogypsum is 40-60° C., and the drying time is 24-48 hours.

8. The method for preparing a soil ecological restoration matrix using phosphogypsum as a main raw material according to claim 4, wherein: The drying temperature of fly ash and carbide slag is 80-105℃, and the drying time is 12-24 hours.

9. Use of the soil ecological restoration matrix with phosphogypsum as the main raw material according to any one of claims 1 to 3 in mine ecological restoration or desertification area ecological restoration.

10. Use of the soil ecological restoration matrix with phosphogypsum as the main raw material as a topsoil substitute material for landscaping.

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