Method for treating soil by using phosphate tailings

Abstract

The method comprises the following steps: grinding and sieving phosphate tailings, weighing a certain amount of phosphate tailings, adding deionized water according to a certain solid-to-liquid ratio, preheating in a constant-temperature water bath, and heating and stirring; adding a phosphoric acid solution at a certain temperature, and stirring to react for a period of time; after the reaction is finished, drying a product in a drying oven, and grinding to obtain modified phosphate tailings; mixing phosphate tailings, the modified phosphate tailings, plant ash, humic acid and charcoal to obtain phosphate tailing soil; the phosphate tailing soil is used for planting plants, so that phosphate tailing waste utilization is realized; the phosphorus tailings are treated into the soil for plant growth, the preparation process is simple, the energy consumption is low, the problems of land resource occupation, environmental pollution and the like caused by phosphorus tailings stacking are relieved, resource utilization of the phosphorus tailings is achieved, and a solution is provided for reduction and resource utilization of the phosphorus tailings.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of soil improvement and bulk solid waste resource utilization, and particularly relates to a method for soilizing phosphorus tailings. BACKGROUND

[0002] Phosphorus tailings refer to solid waste with low phosphorus content generated in the process of phosphorus ore mining and beneficiation, which is stored in a tailings pond. The storage of phosphorus tailings not only occupies valuable land resources and consumes funds, but also brings potential environmental pollution risks. Harmful substances in the phosphorus tailings can enter groundwater through percolation, causing water pollution and threatening the ecological environment. Therefore, resource utilization and reduction of phosphorus tailings have become a problem to be solved.

[0003] At present, the main ways of resource utilization of phosphorus tailings are: making roadbed filling materials, preparing building materials, recovering useful elements, and preparing soil conditioners. These methods can utilize a certain amount of phosphorus tailings, but still have problems such as low utilization rate, high cost, and inconvenient transportation.

[0004] The main chemical components of phosphorus tailings are calcium oxide, magnesium oxide, diaphosphorus pentoxide, carbon dioxide in the form of carbonate, a small amount of silicon dioxide and diiron trioxide, and trace amounts of Al, Mn, Zn, and other element compounds. Phosphorus tailings are rich in calcium, phosphorus, potassium, magnesium, and other nutrients needed for plant growth, so phosphorus tailings are more conducive to the production of fertilizers or soilization for mine reclamation and plant growth. The resource utilization of phosphorus tailings and ecological restoration not only utilizes the stored phosphorus tailings, but also improves the ecological environment.

[0005] Patent CN117296671A discloses a method for soilizing phosphorus tailings in situ and application. The method is: laying phosphorus tailings in situ on an empty land near the mine, adding clay minerals and compound fertilizer on the phosphorus tailings, mixing the surface layer after plowing to obtain a tailings matrix; adding blue-green algae to the tailings matrix and planting herbaceous plants, harvesting the herbaceous plants for composting and applying them as fertilizer in the tailings matrix to obtain a once-treated tailings matrix; adding microorganisms to the once-treated tailings matrix and planting shrubs, and cultivating for 1-3 generations to realize the in-situ soilization of phosphorus tailings. The method directly soilizes the phosphorus tailings on the mine, reducing transportation costs, and the soilized phosphorus tailings can be directly used to repair the mine environment damaged by mining. However, the method is complex and requires a long time, resulting in a long production cycle.

[0006] The patent CN118357263A discloses a method for ecological utilization of phosphorus tailing soil, which comprises the following steps: taking phosphorus tailings from a phosphorus tailing stockyard, adding sterile water, oscillating at 150-200 r / min and 25-35 DEG C, taking supernatant to an organic lecithin liquid medium, oscillating at 150-200 r / min and 25-35 DEG C until the viable count of the culture solution is 1*10 9 cfu / mL, adding 25 mL of the culture solution to 100 mL of sterile water to prepare a phosphorus-dissolving bacteria culture; mixing 85%-95% of the phosphorus tailings, 0.5%-3% of a fluorine-fixing and phosphorus-fixing agent, 4%-6% of a high-organic-matter fertilizer, and 0.5%-6% of an auxiliary material to prepare modified phosphorus tailings soil; spraying the phosphorus-dissolving bacteria culture on the modified phosphorus tailings soil and mixing, for use in planting plants, or applying a magnetic field in planting to strengthen the action of the phosphorus-dissolving bacteria and realize ecological utilization of the phosphorus tailings soil; the method solves the problem of leaching of fluorides and heavy metals during the stockpiling of the phosphorus tailings and realizes harmless and resourceful utilization of the phosphorus tailings, but the method uses a magnetic field to strengthen the action of the phosphorus-dissolving bacteria, which increases the cost and the operation process is relatively complex.

[0007] However, the phosphorus tailings have poor physicochemical properties and lack of nutrients, which seriously limits the soil conversion efficiency of the phosphorus tailings, and therefore, how to accelerate the conversion speed of the phosphorus tailings to soil and make the phosphorus tailings suitable for plant growth has become a problem to be solved. SUMMARY

[0008] In view of the above problems of the grinding tool in use, the present application is proposed.

[0009] Therefore, the present application aims to provide a method for soil conversion of phosphorus tailings, which solves the above technical problems.

[0010] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0011] A method for soil conversion of phosphorus tailings, characterized in that it comprises the following steps:

[0012] S1, preparing modified phosphorus tailings: grinding the phosphorus tailings, screening, mixing a certain amount of the phosphorus tailings with water under stirring, heating in a water bath to a set temperature, adding a phosphoric acid solution for reaction, cooling, drying and grinding after the reaction to obtain the modified phosphorus tailings;

[0013] S2, preparing phosphorus tailings soil: mixing the phosphorus tailings, the modified phosphorus tailings prepared in step S1, wood ash, humic acid and biochar in a certain proportion;

[0014] S3, using the phosphorus tailings soil prepared in step S2 for plant planting.

[0015] Preferably, in step S1, the phosphorus tailings are ground and then passed through a 80-120 mesh sieve.

[0016] Preferably, in step S1, the ratio of the amount of the phosphorus tailings to the amount of water is 1g:(1-5)mL.

[0017] Preferably, in step S1, the stirring speed is 200-400r / min.

[0018] Preferably, in step S1, the temperature of the water bath heating is 40-80℃.

[0019] Preferably, in step S1, the mass fraction of the phosphoric acid solution is 30%-90%, and the ratio of the amount of the phosphorus tailings to the amount of the phosphoric acid solution is 1g:(0.5-3)mL.

[0020] Preferably, in step S1, the reaction time is 0.5-2h, and the drying temperature is 80-100℃.

[0021] Preferably, in step S2, the ratio of the components is, by mass percentage: phosphorus tailings 90.898%-94.498%, modified phosphorus tailings 0.012%, wood ash 0.2%-0.5%, humic acid 5%-8%, and biochar 0.29%-0.59%, and the mixing is mechanical stirring mixing for 5-30min.

[0022] A method for preparing a soil conditioner from phosphorus tailings, the ratio of the components is: phosphorus tailings 94.498%, modified phosphorus tailings 0.012%, wood ash 0.2%, humic acid 5%, and biochar 0.29%.

[0023] Preferably, in step S3, the plants include herbaceous plants, shrubs, or crops.

[0024] In the above technical solution, the present application provides technical effects and advantages:

[0025] The method for preparing the phosphorus tailings soil is simple and mild, does not produce secondary pollutants during the preparation process, has the advantages of environmental protection, and the use method is simple, i.e., directly planting plants in the phosphorus tailings soil, which can save labor costs and facilitate popularization and application.

[0026] The main component of the phosphorus tailings soil is phosphorus tailings, which contains elements such as calcium, magnesium, and phosphorus, which are components of soil, and planting plants in the phosphorus tailings soil can greatly reduce the storage amount of phosphorus tailings, achieving the purposes of phosphorus tailings reduction and resource utilization.

[0027] The phosphorus tailing soil prepared by the method has a large amount of calcium, phosphorus, magnesium and other elements, which are all nutrient elements required by plant growth, and can be directly absorbed by plants when planting plants, and is beneficial to plant growth. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art according to these drawings.

[0029] Figure 1 XRD diffraction pattern of modified phosphorus tailing modified by 80℃ and 12mL phosphoric acid;

[0030] Figure 2 XRD diffraction pattern of modified phosphorus tailing modified by 70℃ and 12mL phosphoric acid;

[0031] Figure 3 XRD diffraction pattern of modified phosphorus tailing modified by 70℃ and 8mL phosphoric acid;

[0032] Figure 4 XRD diffraction pattern of phosphorus tailing;

[0033] Figure 5 Wheat growth condition diagram. DETAILED DESCRIPTION

[0034] The present application will be further described below, and the following embodiments are only used to further illustrate the technical solutions of the present application, and do not limit the protection scope of the present application:

[0035] Example 1

[0036] Preparation of modified phosphorus tailing 1: phosphorus tailing is ground and passed through a 100 mesh sieve, 10g of phosphorus tailing is weighed and added to a 200mL beaker, 15mL of ultrapure water is added; the beaker is placed in a constant temperature water bath for preheating, stirring at a speed of 300r / min, adjusting the reaction temperature to 80℃, after reaching the specified temperature, 12mL of 85% mass fraction phosphoric acid solution is added, and stirring reaction is carried out for 1 hour; after the reaction is completed, cooling is carried out, the product is placed in a 90℃ oven for drying, and finally grinding is carried out to obtain modified phosphorus tailing 1, the XRD diffraction pattern of the product is shown in Figure 1. Figure 1 .

[0037] Preparation of modified phosphorus tailing soil: the above substances are mixed in the proportion of phosphorus tailing 94.498%, modified phosphorus tailing 0.012%, wood ash 0.2%, humic acid 5% and biochar 0.29% to prepare phosphorus tailing soil.

[0038] Example 2

[0039] Preparation of modified phosphorus tailings 2: The phosphorus tailings were ground and passed through a 100-mesh sieve. 10 g of the phosphorus tailings were added to a 200-mL beaker, and 15 mL of ultrapure water was added. The beaker was preheated in a constant-temperature water bath, and stirring was performed at a speed of 300 r / min. The reaction temperature was adjusted to 70°C. After the temperature reached the specified value, 10 mL of a 85% by mass phosphoric acid solution was added, and the reaction was stirred for 1 hour. After the reaction was completed, the product was cooled and dried in a 90°C oven. Finally, the product was ground and crushed to obtain modified phosphorus tailings 2. The XRD diffraction pattern of the product is shown in Figure 2. Figure 2 .

[0040] Preparation of modified phosphorus tailings soil: For ease of comparison, the substances and proportions added were the same as in Example 1.

[0041] Example 3

[0042] Preparation of modified phosphorus tailings 3: The phosphorus tailings were ground and passed through a 100-mesh sieve. 10 g of the phosphorus tailings were added to a 200-mL beaker, and 15 mL of ultrapure water was added. The beaker was preheated in a constant-temperature water bath, and stirring was performed at a speed of 300 r / min. The reaction temperature was adjusted to 50°C. After the temperature reached the specified value, 15 mL of a 50% by mass phosphoric acid solution was added, and the reaction was stirred for 1 hour. After the reaction was completed, the product was cooled and dried in a 90°C oven. Finally, the product was ground and crushed to obtain modified phosphorus tailings 3. The XRD diffraction pattern of the product is shown in Figure 3. Figure 3 .

[0043] Preparation of modified phosphorus tailings soil: For ease of comparison, the substances and proportions added were the same as in Example 1.

[0044] From Figure 1 , Figure 2 , Figure 3 it can be seen that the main component of the phosphorus tailings modified by phosphoric acid treatment is calcium dihydrogen phosphate, and only Figure 3 a small amount of calcium hydrogen phosphate. It is worth noting that calcium dihydrogen phosphate (Ca(H2PO4)2) has high water solubility, and the phosphorus therein mainly exists in the form of H2PO4 - (phosphate dihydrogen ion), which can be directly dissolved in water and is effective phosphorus, which can be rapidly absorbed by plant roots. Therefore, it is often used as a quick-acting phosphorus fertilizer to promote early growth and root development of plants. Calcium hydrogen phosphate (CaHPO4) has low solubility, and the phosphorus therein mainly exists in the form of HPO4 - (phosphate hydrogen ion), which is difficult to be directly absorbed by plants in neutral and alkaline soils and is slow-acting phosphorus. It needs to be reacted with water or acid in the soil to partially convert to H2PO4 - before it can be utilized by plants. Therefore, it is suitable for use as a base fertilizer.

[0045] Comparative Example

[0046] Preparation of phosphate tailings soil: Grind the phosphate tailings and pass through a 100-mesh sieve. The XRD diffraction pattern is shown in the attached Figure 4 The modified phosphate tailings soil was prepared by mixing the above materials in a ratio of 94.51% phosphate tailings, 0.2% wood ash, 5% humic acid and 0.29% biochar.

[0047] Performance Testing

[0048] The phosphate tailings soil prepared in the above embodiments and comparative examples was used for wheat planting experiments. A potting method was adopted under natural conditions, and 3 parallels were set up for each experimental group. Using a seedling tray as a culture container, phosphate tailings, modified phosphate tailings, wood ash, humic acid and biochar were fully mixed and placed in the seedling tray respectively, and 3 full wheat seeds were sown in each hole. Cultivation was carried out under natural temperature conditions. After sowing, irrigation reached 70% of the field water holding capacity, and water was regularly supplemented during the cultivation process. Natural cultivation was carried out for 28 days, and its changes were observed and recorded. The seeds were harvested after 28 days.

[0049] Test results

[0050] After 7 days of cultivation, the germination of wheat was observed; after 28 days of cultivation, the growth of wheat was as follows: Figure 5 As shown, the wheat plant height and the average fresh weight and dry weight of the wheat above the soil were measured, and the moisture content was calculated. The results are shown in Table 1. Obviously, the germination rate of the embodiment (above 66.67%) was significantly higher than that of the comparative example (44.44%). The wheat plant height of Example 1 averaged 9.5 cm and the moisture content was 81.97%, followed by Examples 3 and 2. The plant height and moisture content of the comparative example were the lowest. The average fresh weights of Examples 1, 2, and 3 were also higher than those of the comparative example.

[0051] To comprehensively evaluate the germination performance and growth status of each treatment group, the "germination quality index" was introduced as an evaluation parameter. This index takes into account both the germination ability of seeds and the growth level of plants after germination by multiplying the germination rate with average growth indicators (such as average fresh weight and average plant height), providing a more holistic evaluation method for treatment effects:

[0052] Germination quality index formula: Germination quality index (GQI) = germination rate × average fresh weight.

[0053] The results are shown in Table 1. The germination quality index of the embodiment is 2.8 to 6.5 times that of the comparative example, which fully demonstrates that the modified phosphate tailings in the embodiment have a significant soil effect, can meet the growth needs of plants at different stages, have the ecological function of soil, and show good application potential.

[0054] Table 1 Statistics of wheat growth parameters

[0055]

[0056] The water-soluble fluorine was leached according to the method of "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method" HJ 557-2010, and determined according to the method of "Determination of Fluoride in Solid Waste Ion Selective Electrode Method" GB / T 15555.11-1995, and the results are shown in Table 2. The results show that the concentration of fluorine ions in each group ranges from 1.432 to 1.524 mg / kg, with little fluctuation, and has good stability. Considering that the state has not yet set a mandatory limit for water-soluble fluorine in soil, this paper refers to the limit value of fluorine in "Groundwater Quality Standard" (GB / T 14848-2017) and "Drinking Water Health Standards" (GB 5749-2022) (both 1.0 mg / L). Although this value is a water quality standard, it can be used as a reference for judging the environmental safety of the material. Compared with it, the release amount of water-soluble fluorine in the application is much lower than the above limit value, indicating that it has no obvious fluorine pollution risk in environmental application, and has good environmental friendliness and application prospect.

[0057] Table 2 Water-soluble fluorine content of soil phosphorized tailings

[0058]

[0059] It should be understood that the embodiments of the present application are not limited to the precise construction that has been described above and illustrated in the accompanying drawings, and that various modifications and changes can be made without departing from the scope thereof. The scope of the embodiments of the present application is only limited by the appended claims.

[0060] The above-described embodiments only express several implementation manners of the embodiments of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the embodiments of the present application, several modifications and improvements can be made, which are within the scope of protection of the embodiments of the present application.

Claims

1. A method for soilification of phosphate tailings, characterized in that: The steps include: S1. Preparing modified phosphate tailings: grinding the phosphate tailings, sieving, mixing a certain amount of the phosphate tailings with water, heating in a water bath under stirring, adding a phosphoric acid solution after reaching a set temperature to react, and cooling, drying, and grinding after the reaction is completed to obtain the modified phosphate tailings; S2. Preparing phosphate tailings soil: mixing phosphate tailings, the modified phosphate tailings obtained in step S1, wood ash, humic acid and biochar in a certain proportion; S3. Using the phosphate tailings soil obtained in step S2 for plant cultivation.

2. The method for soilification of phosphorus tailings according to claim 1, wherein In step S1, the phosphate tailings are ground and then passed through an 80-120 mesh sieve.

3. The method for soilification of phosphorus tailings according to claim 1, wherein In step S1, the ratio of the phosphate tailings to water is 1 g: (1-5) mL.

4. The method for soilification of phosphorus tailings according to claim 1, wherein In step S1, the stirring speed is 200-400 r / min.

5. The method for soilification of phosphorus tailings according to claim 1, wherein: In step S1, the water bath is heated at a temperature of 40-80°C.

6. The method for soilification of phosphorus tailings according to claim 1, wherein: In step S1, the mass fraction of the phosphoric acid solution is 30% to 90%, and the usage ratio of the phosphate tailings to the phosphoric acid solution is 1 g: (0.5-5) mL.

7. The method for soilification of phosphate tailings according to claim 1, wherein: In step S1, the reaction time is 0.5 to 2 hours; the drying temperature is 80-100°C.

8. The method for soilification of phosphorus tailings according to claim 1, wherein: In step S2, the proportions of the components are as follows by mass percentage: 90.898% to 94.498% of phosphate tailings, 0.012% of modified phosphate tailings, 0.2% to 0.5% of wood ash, 5% to 8% of humic acid, and 0.29% to 0.59% of biochar. The mixing is performed by mechanical stirring, and the stirring time is 5 to 30 minutes.

9. The method for preparing a soil conditioner using phosphate tailings according to claim 8, wherein: The specific proportions of the components are as follows: 94.498% of phosphate tailings, 0.012% of modified phosphate tailings, 0.2% of wood ash, 5% of humic acid, and 0.29% of biochar are mixed to prepare phosphate tailings soil.

10. The method for converting phosphate tailings into soil according to claim 1, wherein: In step S3, the plants include herbaceous plants, shrubs or crops.

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