Preparation method of phosphorite powder / shell powder composite ball-milling material and application thereof

Abstract

A method for preparing a composite ball-milled material of phosphate rock powder and shell powder and its application are disclosed, relating to the field of composite ball-milled material preparation technology. The purpose of this invention is to solve the problem of how to passivate the heavy metal Cd in soil while simultaneously improving acidic soil and providing phosphorus. Method: Pretreated phosphate rock powder and shell powder are mixed and stirred evenly to obtain a mixture. The mass ratio of phosphate rock powder to shell powder is (1-4):2. The mixture is transferred to an agate jar of a ball mill, and three types of agate balls of different sizes are added to the jar. After mixing evenly, the mixture is ball-milled for 6-18 hours. After ball milling, the material is removed from the agate jar, ground, and sieved to obtain a composite ball-milled material of phosphate rock powder and shell powder. This invention provides a method for preparing a composite ball-milled material of phosphate rock powder and shell powder and its application.

Description

Technical Field

[0001] This invention relates to the field of composite ball milling material preparation technology, specifically to a method for preparing a phosphate rock powder / shell powder composite ball milling material and its application. Background Technology

[0002] Cadmium in soil can be absorbed by plants and enter the human body through the food chain, thus affecting human health. It is worth noting that the chemical form of cadmium in soil affects its stability, solubility, and toxicity; therefore, reducing cadmium migration in soil is key to remediating cadmium-contaminated soil. Acidic soil environments not only affect the normal growth of crops, but cadmium also migrates more rapidly in acidic environments, causing more serious harm. Therefore, finding suitable methods to simultaneously passivate the heavy metal cadmium, improve acidic soil, and provide phosphorus to meet crop growth needs is urgently needed.

[0003] Currently, soil leaching, chemical oxidation, and adsorption are widely used in the remediation of heavy metal pollution in soil. However, due to their high cost, difficulty in recovering adsorbents from the soil, and potential for secondary pollution, these methods are rarely used in farmland soils. Furthermore, these methods are not effective in improving acidic soils or providing phosphorus nutrients to plants. Phosphate rock powder is a natural mineral, its main components being phosphorus pentoxide and calcium metaphosphate, and it is often used as a slow-release phosphate fertilizer applied to the soil as top dressing. In addition, because it contains some calcium... 2+ and Mg 2+ It is a cation that can react with Cd after being applied to the soil. 2+ Phosphate rock powder also serves as a soil heavy metal passivator through ion exchange to reduce the availability of cadmium in soil. However, phosphate rock powder is not effective in improving acidic soils, and its large particle size also results in a relatively slow effect. Therefore, it is necessary to process phosphate rock powder to give it superior performance.

[0004] Shell powder is a powdery substance made from the crushed shells of oysters and freshwater mussels. Rich in calcium carbonate and calcium oxide, it is often used to improve acidic soils. Shell powder has a porous structure, which facilitates the adsorption of pollutants. Furthermore, it releases alkaline substances when it comes into contact with water, effectively modifying acidic soils. However, shell powder cannot alleviate phosphorus deficiency symptoms in plants, and it has a significant impact on pH; excessive alkalinity can harm plants. In practical applications, shell powder is usually used in combination with other materials or modified to reduce its alkalinity. Therefore, choosing appropriate methods to treat shell powder and apply it to farmland is crucial. Summary of the Invention

[0005] The purpose of this invention is to solve the problem of how to passivate the heavy metal Cd in soil while improving acidic soil and providing phosphorus, and to provide a method for preparing a composite ball milling material of phosphate rock powder / shell powder and its application.

[0006] A method for preparing a composite ball-milled material of phosphate rock powder / shell powder, comprising the following steps:

[0007] Step 1: Pretreatment of phosphate rock powder and shell powder:

[0008] Phosphate rock powder and shell powder were dried in an oven, then ground and sieved to obtain pretreated phosphate rock powder and shell powder.

[0009] Step 2: Preparation of phosphate rock powder / shell powder composite ball milling material:

[0010] The pretreated phosphate rock powder and shell powder are mixed and stirred evenly to obtain a mixture. The mass ratio of phosphate rock powder to shell powder is (1-4):2. The mixture is transferred to the agate jar of a ball mill, and three kinds of agate balls of different sizes are added to the agate jar of the ball mill. After mixing evenly, the mixture is ball milled for 6-18 hours. After the ball milling is completed, the material in the agate jar of the ball mill is taken out, ground, and sieved to obtain a composite ball milling material of phosphate rock powder / shell powder.

[0011] An application of a composite ball milling material of phosphate rock powder / shell powder, wherein the composite ball milling material of phosphate rock powder / shell powder is used for passivation of heavy metal cadmium, improvement of acidic soil, and replenishment of phosphorus in soil.

[0012] The principle of this invention:

[0013] First, due to the inherent adsorption capacity of shell powder and phosphate rock powder, some cadmium will be adsorbed and removed, and ball milling helps improve the adsorption performance of the materials. Simultaneously, shell powder helps regulate the pH of acidic soils, as some free cadmium ions are precipitated out in a higher pH environment. Furthermore, because shell powder contains a large amount of calcium ions, it can undergo ion exchange with cadmium ions, reducing the cadmium ion content in the soil. Finally, the introduction of phosphate rock powder releases a large amount of available phosphorus into the soil to meet the needs of crop growth, and the introduction of phosphate rock powder can assist shell powder in regulating soil pH, preventing the soil from becoming too alkaline and affecting plant growth.

[0014] The beneficial effects of this invention are:

[0015] I. This invention prepares a composite ball milling material of phosphate rock powder / shell powder by ball milling, which is used to remediate heavy metal Cd in farmland soil, while improving acidic soil and providing phosphorus nutrients. It has the advantages of simple synthesis, good remediation effect and green environmental protection. Its main mechanism of action includes: (1) Ion exchange between Cd and protons on oxygen-containing functional groups (carboxyl, hydroxyl, etc.) of the composite ball milling material of phosphate rock powder / shell powder enhances the adsorption of Cd; (2) The composite ball milling material of phosphate rock powder / shell powder also has a certain pore structure, and Cd can enter into the pores through diffusion, and then be deposited on the surface of the remediation agent through pore filling; (3) The composite ball milling material of phosphate rock powder / shell powder contains components such as calcium oxide, which becomes alkaline after contact with water, changing the soil pH; (4) The composite ball milling material of phosphate rock powder / shell powder contains abundant Ca 2+ Mg 2+ It can be used with Cd 2+ Cation exchange occurs, reducing the availability of Cd in the soil; (5) The phosphate rock powder / shell powder composite ball milling material is rich in phosphates, which can release a large amount of phosphorus into the soil. Therefore, the prepared phosphate rock powder / shell powder composite ball milling material simultaneously achieves the passivation of heavy metal Cd in farmland, the improvement of acidic soil, and the replenishment of soil phosphorus, promoting the development and application of farmland soil conditioners with heavy metal passivation function.

[0016] II. Currently, there is limited research on preparing soil cadmium passivating agents that simultaneously regulate soil pH and release phosphorus nutrients. From a practical application perspective, materials prepared based on inexpensive and pollution-free shell powder and phosphate rock powder are more competitive than other modified materials. Furthermore, exploring the appropriate ball milling ratio of shell powder and phosphate rock powder for practical applications, ensuring efficient passivation of soil cadmium while adjusting soil pH to near neutral and releasing phosphorus nutrients, is of great significance for safe agricultural production.

[0017] Third, among numerous soil modification methods, ball milling technology is a simple, efficient, and economical approach. Ball milling effectively combines shell powder and phosphate rock powder, creating a soil conditioner that can passivate heavy metals in the soil, provide phosphorus to farmland, and reduce the alkalinity of the shell powder, making it more suitable for farmland application. Furthermore, ball milling technology enables large-scale production, meeting the needs of agricultural land.

[0018] IV. This invention prepares phosphate rock powder / shell powder composite material by ball milling, explores the passivation performance of phosphate rock powder / shell powder composite material on soil Cd and its effects on soil pH and available phosphorus content, and analyzes its related mechanism of action.

[0019] This invention provides a method for preparing a composite ball milling material of phosphate rock powder / shell powder and its application. Attached Figure Description

[0020] Figure 1 This is a scanning electron microscope image of a composite ball-milled material of phosphate rock powder / shell powder from Example 1;

[0021] Figure 2 The Fourier transform infrared spectrum of a composite ball-milled material of phosphate rock powder / shell powder in Example 1 is shown. A represents ball-milled shell powder, B represents ball-milled phosphate rock powder, and C represents ball-milled phosphate rock powder + shell powder.

[0022] Figure 3 The image shows an X-ray diffraction pattern of a composite ball-milled phosphate rock powder / shell powder material from Example 1. A represents ball-milled shell powder, B represents ball-milled phosphate rock powder, and C represents ball-milled phosphate rock powder + shell powder. ★ indicates Ca(PO3)2, ★ indicates Ca3(PO4)2, and ◆ indicates P2O5. It represents CaCO3;

[0023] Figure 4 This diagram illustrates the effect of a phosphate rock / shell powder composite ball-milled material from Example 1 on soil pH. ■ indicates 0.5% without ball milling, ● indicates 1.0% without ball milling, ▲ indicates 1.5% without ball milling, ▼ indicates 0.5% with ball milling, and ◆ indicates 1.0% with ball milling. This indicates 1.5% ball milling;

[0024] Figure 5 The image shows the passivation effect of a composite ball milling material of phosphate rock powder / shell powder on available cadmium in soil in Example 1. a represents the original soil, b represents the unmilled soil, and c represents the milled soil.

[0025] Figure 6 The graph shows the effect of a composite ball milling material of phosphate rock powder / shell powder on the effective phosphorus content of soil in Example 1. a represents the original soil, b represents the unmilled soil, and c represents the milled soil. Detailed Implementation

[0026] Specific Implementation Method 1: This implementation method describes a method for preparing a composite ball-milled material of phosphate rock powder / shell powder, which is carried out according to the following steps:

[0027] Step 1: Pretreatment of phosphate rock powder and shell powder:

[0028] Phosphate rock powder and shell powder were dried in an oven, then ground and sieved to obtain pretreated phosphate rock powder and shell powder.

[0029] Step 2: Preparation of phosphate rock powder / shell powder composite ball milling material:

[0030] The pretreated phosphate rock powder and shell powder are mixed and stirred evenly to obtain a mixture. The mass ratio of phosphate rock powder to shell powder is (1-4):2. The mixture is transferred to the agate jar of a ball mill, and three kinds of agate balls of different sizes are added to the agate jar of the ball mill. After mixing evenly, the mixture is ball milled for 6-18 hours. After the ball milling is completed, the material in the agate jar of the ball mill is taken out, ground, and sieved to obtain a composite ball milling material of phosphate rock powder / shell powder.

[0031] Specific Implementation Method Two: The difference between this implementation method and Specific Implementation Method One is that the drying temperature in step one is 60-80℃.

[0032] The other steps are the same as in Specific Implementation Method 1.

[0033] Specific Implementation Method 3: The difference between this implementation method and Specific Implementation Method 1 or 2 is that the drying time in step 1 is 2 to 6 hours.

[0034] The other steps are the same as in Specific Implementation Method 1 or 2.

[0035] Specific Implementation Method Four: The difference between this implementation method and Specific Implementation Methods One to Three is that the grinding process in Step One is passed through a 200-mesh sieve.

[0036] The other steps are the same as those in Specific Implementation Methods One to Three.

[0037] Specific Implementation Method Five: The difference between this implementation method and Specific Implementation Methods One to Four is that the mass ratio of phosphate rock powder and shell to agate ball in step two is 1:(20-40).

[0038] The other steps are the same as those in Specific Implementation Methods One through Four.

[0039] Specific Implementation Method Six: The difference between this implementation method and Specific Implementation Methods One to Five is that the agate balls added to the agate jar of the ball mill in step two are in a ratio of 3:15:15 in descending order of size.

[0040] The other steps are the same as those in Specific Implementation Methods 1 to 5.

[0041] Specific Implementation Method Seven: The difference between this implementation method and Specific Implementation Methods One to Six is ​​that: after mixing evenly in step two, the mixture is ball-milled at a speed of 300-500 r / min for 6-18 hours.

[0042] The other steps are the same as those in Specific Implementation Methods 1 to 6.

[0043] Specific Implementation Method Eight: The difference between this implementation method and Specific Implementation Methods One to Seven is that in step two, the stirring direction is changed every 3 to 6 hours during the ball milling process.

[0044] The other steps are the same as those in Specific Implementation Methods 1 to 7.

[0045] Specific Implementation Method Nine: The difference between this implementation method and Specific Implementation Methods One to Eight is that in step two, the material is passed through a 200-mesh sieve after grinding.

[0046] The other steps are the same as those in Specific Implementation Methods 1 to 8.

[0047] Specific Implementation Method 10: This implementation method describes the application of a composite ball milling material made from phosphate rock powder and shell powder. The composite ball milling material is used for the passivation of heavy metal cadmium, the improvement of acidic soil, and the replenishment of phosphorus in the soil.

[0048] The beneficial effects of the present invention are verified using the following embodiments:

[0049] Example 1: A method for preparing a composite ball-milled material of phosphate rock powder / shell powder, comprising the following steps:

[0050] Step 1: Pretreatment of phosphate rock powder and shell powder:

[0051] The phosphate rock powder and shell powder were spread separately in an oven and dried at a constant temperature of 80°C for 2 hours. After being taken out, they were ground separately and passed through a 200-mesh sieve to obtain the pretreated phosphate rock powder and shell powder for later use.

[0052] Step 2: Preparation of phosphate rock powder / shell powder composite ball milling material:

[0053] 2g of pretreated phosphate rock powder and 1g of shell powder were added to a beaker and stirred evenly with a glass rod to obtain a mixture. The mixture was then transferred to the agate jar of a ball mill, and three types of agate balls were added in the agate jar at a ratio of large balls: medium balls: small balls = 3:15:15. The mass ratio of phosphate rock powder and shell powder to agate balls was 1:20. After mixing evenly, the mixture was ball milled at 300 r / min for 12 h, with the stirring direction changed every 3 h during the ball milling process. After the ball milling was completed, the material in the agate jar of the ball mill was removed, ground, and passed through a 200-mesh sieve to obtain a composite ball milling material of phosphate rock powder / shell powder.

[0054] The phosphate rock powder / shell powder composite ball-milled material prepared in this embodiment was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and experiments on the effects of soil pH, soil Cd remediation, and soil available phosphorus release. The specific conclusions are as follows:

[0055] 1. Characterization (scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction):

[0056] The surface morphology, functional groups, and elemental composition of the phosphate rock powder / shell powder composite ball milling material were determined by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction.

[0057] Figure 1 This is a scanning electron microscope (SEM) image of a composite ball-milled phosphate rock powder / shell powder material from Example 1; as shown. Figure 1 As shown, the phosphate rock powder / shell powder composite ball milling material aggregates into a granular cluster structure and has a large number of pore structures, indicating that the phosphate rock powder / shell powder composite ball milling material has excellent adsorption capacity.

[0058] Figure 2 The Fourier transform infrared spectrum of a composite ball-milled material of phosphate rock powder / shell powder in Example 1 is shown below. Figure 2 As shown, the phosphate rock powder / shell powder composite ball milling material has characteristic peaks of carbonate, hydroxyl and phosphate, indicating that the ball milling process successfully combines phosphate rock powder and shell powder and enhances their effect.

[0059] Figure 3 The image shows the X-ray diffraction pattern of a composite ball-milled material of phosphate rock powder / shell powder in Example 1; as shown. Figure 3 As shown, the main phases in the phosphate rock powder / shell powder composite ball milling material are calcium phosphate, phosphorus pentoxide, and calcium carbonate, proving the successful synthesis of this material.

[0060] 2. The effect of phosphate rock powder / shell powder composite ball milling material on soil pH:

[0061] Experimental conditions: Soil samples were obtained from the field in Yunnan Province. The soil was ground, passed through a 200-mesh sieve, and then placed into cylindrical boxes 10 cm high and 5 cm in diameter, with 100 g of soil per box. The phosphate rock / shell powder composite ball milling material was accurately weighed at dosages of 0.5%, 1.0%, and 1.5%, and mixed thoroughly with the soil. The mixture was then incubated at room temperature, maintaining the soil moisture content at 60% of field capacity using a weighing method. Samples were taken on days 1, 3, 5, 7, and 10 of incubation. After the soil samples were air-dried, they were ground and sieved. The soil pH was determined using a solid-liquid ratio of 1:5.

[0062] Figure 4 This is a diagram illustrating the effect of a phosphate rock powder / shell powder composite ball milling material on soil pH in Example 1; as shown. Figure 4 As shown, the phosphate rock powder / shell powder composite ball-milled material effectively increases the pH of acidic soils after application, and the pH increases with increasing dosage. At a dosage of 1.5%, the soil pH approaches neutral. Furthermore, the phosphate rock powder / shell powder composite ball-milled material effectively improves soil pH within one day of application, demonstrating a rapid effect; the soil pH change is minimal after ten days, indicating good stability of the material. Moreover, the effect is even better after ball milling, indicating that ball milling treatment successfully modifies the material.

[0063] 3. Passivation effect of phosphate rock powder / shell powder composite ball milling material on available cadmium in soil:

[0064] Figure 5 This is a diagram illustrating the passivation effect of a phosphate rock powder / shell powder composite ball milling material on available cadmium in soil, as shown in Example 1. Figure 5 As shown, the content of available cadmium in the soil significantly decreased one day after application of the phosphate rock powder / shell powder composite ball-milled material, and the available content continued to decline after the first day, indicating that the material has a rapid and stable passivation effect on cadmium. After 10 days, the available cadmium in the soil at a dosage of 1.5% decreased from 0.1042 mg / kg to 0.04537 mg / kg. Furthermore, compared with the unmilled control material, the ball-milled material showed a more significant effect, indicating that ball milling treatment resulted in a larger specific surface area and greater release of available substances, promoting cadmium adsorption and precipitation, and contributing to the passivation of the heavy metal cadmium.

[0065] 4. The effect of phosphate rock powder / shell powder composite ball milling material on the available phosphorus content of soil;

[0066] Figure 6 This is a graph showing the effect of a composite ball-milled phosphate rock powder / shell powder material on the available phosphorus content of soil in Example 1; as shown. Figure 6 As shown, after 10 days of application of the phosphate rock powder / shell powder composite ball-milled material into the soil, the available phosphorus content of the soil increased by 760.0 mg / kg compared to the original soil, and the available phosphorus content showed an increasing trend with increasing time and dosage. Compared to before ball milling, the material after ball milling showed better results, indicating that ball milling treatment released more phosphorus-containing substances. Ball-milled phosphate rock powder / shell powder composite ball-milled material can provide the soil with a large amount of phosphorus, better meeting the needs of plant growth.

[0067] In summary, the phosphate rock powder / shell powder composite ball milling material prepared in this embodiment is a highly efficient cadmium passivating agent for acidic soil improvement and can provide phosphorus nutrients to the soil.

Claims

1. A method for preparing a composite ball-milled material of phosphate rock powder / shell powder, characterized in that... The preparation method is carried out according to the following steps: Step 1: Pretreatment of phosphate rock powder and shell powder: Phosphate rock powder and shell powder were dried in an oven, then ground and sieved to obtain pretreated phosphate rock powder and shell powder. Step 2: Preparation of phosphate rock powder / shell powder composite ball milling material: The pretreated phosphate rock powder and shell powder are mixed and stirred evenly to obtain a mixture. The mass ratio of phosphate rock powder to shell powder is (1~4):

2. The mixture is transferred to the agate jar of a ball mill, and three kinds of agate balls of different sizes are added to the agate jar of the ball mill. After mixing evenly, the mixture is ball milled at a speed of 300~500 r / min for 6~18 h. After the ball milling is completed, the material in the agate jar of the ball mill is taken out, ground, and sieved to obtain a phosphate rock powder / shell powder composite ball milling material. In step two, the mass ratio of phosphate rock powder and shell to agate balls is 1:(20~40); in step two, three types of agate balls are added to the agate jar of the ball mill in a ratio of large balls: medium balls: small balls = 3:15:15; during the ball milling process in step two, the stirring direction is changed every 3~6 hours.

2. The method for preparing a composite ball-milled material of phosphate rock powder / shell powder according to claim 1, characterized in that... The drying temperature in step one is 60~80℃.

3. The method for preparing a composite ball-milled material of phosphate rock powder / shell powder according to claim 1 or 2, characterized in that... The drying time in step one is 2 to 6 hours.

4. The method for preparing a composite ball-milled material of phosphate rock powder / shell powder according to claim 1, characterized in that... After grinding in step one, pass the material through a 200-mesh sieve.

5. The method for preparing a composite ball-milled material of phosphate rock powder / shell powder according to claim 1, characterized in that... After grinding in step two, the material is passed through a 200-mesh sieve.

6. The application of a phosphate rock powder / shell powder composite ball milling material prepared by the method according to any one of claims 1-5, characterized in that... The aforementioned phosphate rock powder / shell powder composite ball milling material is used for the passivation of heavy metal cadmium, the improvement of acidic soil, and the replenishment of phosphorus in the soil.

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