A method for crushing zero-valent iron

Abstract

The present invention provides a method for pulverizing zero-valent iron, comprising: adding FeS, FeS2, zero-valent iron powder and absolute ethanol into a container and stirring evenly to form a slurry to be ground; filling grinding beads in a wet ball mill, adding the slurry to be ground into the wet ball mill for grinding to obtain a slurry, and the grinding time is 10 - 640 min; taking out the slurry from the wet ball mill, putting the slurry into a magnetic separation device for separation, collecting the ground zero-valent iron particles and washing them with absolute ethanol; and placing the washed zero-valent iron particles in a vacuum drying oven and drying them at a temperature below 40°C.

Description

Technical Field

[0001] The invention relates to the technical field of particle refinement, and in particular to a method for crushing zero-valent iron. Background Art

[0002] When ultrafine zero-valent iron is used in contaminated site remediation and industrial wastewater treatment, the size of zero-valent iron particles is a key factor in determining its performance and applicability. Compared with large zero-valent iron particles, smaller zero-valent iron particles generally have higher specific surface area and reactivity.

[0003] In the prior art, mechanical grinding is usually used to refine zero-valent iron particles. However, during the mechanical grinding process, since metallic iron (Fe(0)) is ductile and can withstand severe plastic deformation, it is difficult for flaky crushing to occur.

[0004] In the prior art, water is usually used as the grinding medium to prepare nanoscale zero-valent iron by grinding micron-scale zero-valent iron. However, since the mechanical chemical effect accelerates the reaction between iron and water, the effective iron content of the resulting nanoparticles is usually less than 50%, and most of the metallic iron is oxidized, losing its own reducing ability, thereby losing its application value.

[0005] The invention patent with application number 202410639668.4 discloses a method for preparing sulfur-nitrogen modified zero-valent iron by wet ball milling, sulfur-nitrogen modified zero-valent iron and its application. In an alcohol organic solvent, zero-valent iron and organic molecules containing both N and S are wet mixed and ball milled to prepare Fe-S x -N y Co-combined sulfur and nitrogen modified zero-valent iron to avoid oxidation and spontaneous combustion of the material during ball milling.

[0006] However, the above patent not only increases the difficulty of the process, but also the complexity of its doping may limit the reactivity and selectivity of the material in practical applications. In particular, in an environment where multiple pollutants coexist, the different reactivity of the doped elements may affect the pollution remediation effect. At the same time, there is no in-depth research on the particle crushing effect and the uniformity of the particle size, which may lead to the final prepared zero-valent iron particles being larger and having poor transmission performance, limiting its application in groundwater remediation and pollutant diffusion control.

[0007] Therefore, the current technical problem that needs to be solved urgently is still how to crush zero-valent iron into smaller particles while maintaining its high effective iron content so that it can be better used in groundwater remediation and pollutant diffusion control. Summary of the invention

[0008] The present invention is made to solve the above-mentioned problem, and aims to provide a method for crushing zero-valent iron, so that the zero-valent iron can be crushed to a smaller particle size while maintaining the iron content.

[0009] The present invention provides a method for crushing zero-valent iron, which has the following characteristics, comprising: S1, adding FeS, FeS2, zero-valent iron powder and anhydrous ethanol into a container and stirring them evenly to form a slurry to be ground;

[0010] S2, loading grinding beads into a wet ball mill, adding the slurry to be ground into the wet ball mill for grinding to obtain a slurry, and the grinding time is 10-640 min;

[0011] S3, taking out the slurry from the wet ball mill, placing the slurry into a magnetic separation device for separation, collecting the ground zero-valent iron particles and washing them with anhydrous ethanol; and

[0012] S4, placing the washed zero-valent iron particles in a vacuum drying oven and drying them at a temperature below 40°C.

[0013] The method for crushing zero-valent iron provided by the present invention may also have the following characteristics: wherein the diameters of FeS and FeS2 are both 50-60 μm.

[0014] The method for crushing zero-valent iron provided by the present invention may also have the following characteristics: wherein the mass ratio of FeS to FeS2 is 1:(0.9-1.1).

[0015] The method for crushing zero-valent iron provided by the present invention may also have the following characteristics: wherein the mass ratio of the mixture of FeS and FeS2 to the zero-valent iron powder is 1:(0.15-0.25).

[0016] The method for crushing zero-valent iron provided by the present invention may also have the following characteristics: wherein the stirring time is 20-50 minutes.

[0017] The method for crushing zero-valent iron provided by the present invention may also have the following characteristics: wherein the content of zero-valent iron in the zero-valent iron powder is higher than 98.5%, and the median particle size of the zero-valent iron powder is 3.0-3.2 microns

[0018] The method for pulverizing zero-valent iron provided by the present invention may also have the following feature: wherein the grinding beads are zirconia beads with a weight of 0.7-0.8 kg and a diameter of 0.2-0.4 mm.

[0019] The method for crushing zero-valent iron provided by the present invention may also have the following feature: during the grinding process, the temperature in the cavity of the wet ball mill is controlled at 8-12°C.

[0020] Functions and Effects of the Invention

[0021] According to the method for crushing zero-valent iron involved in the present invention, since the present invention adopts FeS and FeS2 as key sulfur sources, they react with zero-valent iron particles during the ball milling process to form a stable sulfide surface layer. These sulfide layers not only protect the zero-valent iron particles from further oxidation, but also improve the chemical stability of the material and the durability and reaction activity in environmental applications. Compared with other vulcanizing agents (such as sodium sulfide), FeS and FeS2 can provide a more uniform vulcanization effect, avoid the problem of over-vulcanization or uneven vulcanization, improve the environmental friendliness of the entire production process, and reduce the potential safety hazards in the production process; the FeS and FeS2 additives of the present invention are embedded in the flaky structure of the zero-valent iron particles during the ball milling process, causing them to break and refine, which not only improves the crushing efficiency, but also prevents the cold welding of particles, so that the final zero-valent iron particles have a smaller particle size and higher uniformity; the present invention adopts wet ball milling technology, and by ball milling in alcohol, it ensures that the crushing process of zero-valent iron is carried out in an oxygen-free environment, reducing the risk of material oxidation. Therefore, the method for crushing zero-valent iron of the present invention has the effects of promoting the crushing of zero-valent iron, preventing iron oxidation, and improving the chemical stability and reaction activity of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the process of preparing ultra-zero-valent iron by wet ball milling.

[0023] Figure 2 It is a schematic diagram of the wet ball milling method using water as the grinding agent.

[0024] Figure 3 This is a schematic diagram of the wet ball milling method using alcohol as the grinding agent.

[0025] Figure 4 It is a process flow chart of the method for pulverizing zero-valent iron in enhanced wet grinding of the present invention.

[0026] Figure 5 It is a structural schematic diagram of the wet ball mill of the present invention.

[0027] Figure 6 The figures are scanning electron microscope images of zero-valent iron ball-milled for 40 minutes and 640 minutes in Example 1 of the present invention and a distribution diagram of particle sizes based on SEM and image pro software statistics.

[0028] Figure 7 1 and 2 are electron microscope images and element distribution diagrams of particles of zero-valent iron after ball milling for 40 minutes and 640 minutes in Example 1 of the present invention.

[0029] Figure 8This is a crystal phase microscope image of zero-valent iron after ball milling for 640 minutes in Example 1 of the present invention.

[0030] Fig. 9 It is the removal capacity of Cr(VI) after 640 minutes of zero-valent iron ball milling in Example 1 of the present invention.

[0031] Fig.10 These are scanning electron microscope images of zero-valent iron ball milled for 10 minutes, 40 minutes, and 640 minutes in Comparative Example 1 of the present invention.

[0032] Fig.11 1 is the removal curve of Cr(VI) by Example 1 of the present invention, Comparative Example 1 and the original iron powder.

[0033] Fig.12 It is the transmission performance of Example 1 and Comparative Example 1 of the present invention and the original iron powder in the porous medium.

[0034] Fig.13 It is a line graph of ball milling time and average particle size of Example 1 of the present invention and Comparative Examples 2-5. DETAILED DESCRIPTION

[0035] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0036] In order to make the technical means, creative features, objectives and effects of the present invention easy to understand, the following embodiments and the accompanying drawings specifically illustrate the method for crushing zero-valent iron of the present invention.

[0037] Figure 1 This is a schematic diagram of the process of preparing ultra-zero-valent iron by wet ball milling. Figure 2 It is a schematic diagram of the wet ball milling method using water as the grinding agent. Figure 3 This is a schematic diagram of the wet ball milling method using alcohol as the grinding agent. Figure 4 It is a process flow chart of the method for pulverizing zero-valent iron in enhanced wet grinding of the present invention.

[0038] like Figure 1-4 As shown, Figure 2 When water is used as a grinding agent, the resulting nanoparticles have a low zero-valent iron content (<50%). Figure 3When alcohol is used as a grinding agent, the resulting nanoparticles have a high content of zero-valent iron (>95%), but cannot be effectively crushed.

[0039] The method for crushing zero-valent iron in this embodiment specifically includes the following steps:

[0040] S1, adding FeS, FeS2, zero-valent iron powder and anhydrous ethanol into a container and stirring evenly to form a slurry to be ground.

[0041] S2, loading grinding beads into a wet ball mill, adding the slurry to be ground into the wet ball mill for grinding to obtain slurry, and the grinding time is 10-640 minutes.

[0042] S3, taking out the slurry from the wet ball mill, placing the slurry into a magnetic separation device for separation, collecting the ground zero-valent iron particles and washing them with anhydrous ethanol.

[0043] S4, placing the washed zero-valent iron particles in a vacuum drying oven and drying them at a temperature below 40°C.

[0044] Figure 5 Schematic diagram of the structure of the wet ball mill 100 of the present invention.

[0045] like Figure 5 As shown, the wet ball mill used in the above method of the present invention comprises a reactor housing 10, a rotor 20, an end cover 30 and a driving mechanism 40. The driving mechanism 40 is used to drive the rotor 20 to rotate, and comprises a main shaft 42, a bearing seat 41, and a pulley 45.

[0046] The reactor shell 10 is generally cylindrical, and has a cavity formed inside, which is the reaction chamber 11. The reactor shell 10 is provided with a feed port 12 and a discharge port 13 connected to the reaction chamber 11, which are used to allow the slurry to enter and flow out of the reaction chamber 11, respectively.

[0047] In the reactor shell 10, a cooling water chamber 14 is formed around the reaction chamber 11 and is not connected to the reaction chamber 11, and is used to contain cooling water for cooling the reaction chamber 11. The cooling water can enter the cooling water chamber through the cooling water inlet 15 and flow out of the cooling water chamber from the cooling water outlet 16.

[0048] The rotor 20 is disposed in the reaction chamber 11 and is columnar with a plurality of annular sheets on the circumference. The surface of the rotor is covered with a layer of polyurethane material to reduce the wear of the ball milling beads on the rotor body.

[0049] The end cover 30 is disposed at one end of the reactor housing 10 , and a middle end cover 31 is installed on the end of the end cover 30 away from the reactor housing 10 .

[0050] The bearing seat 41 is disposed on the other side of the middle end cover 31 relative to the end cover 30 .

[0051] The main shaft 42 is installed in the bearing seat 41 through the bearing 43, and one end of the main shaft 42 passes through the middle end cover 31 and the end cover 30 in sequence and extends into the reaction chamber 11. This end is connected to the rotor 20, so that the main shaft 42 can drive the rotor 20 to rotate.

[0052] A mechanical seal assembly 44 is also provided in the end cover 30 . The mechanical seal assembly 44 is sleeved on the main shaft 42 and is located close to the reaction chamber 11 . The mechanical seal assembly 44 is used to form a seal on the main shaft 42 to prevent the liquid in the reaction chamber 11 from leaking to the bearing seat 41 and other parts.

[0053] The other end of the main shaft 42 extends to the outside of the bearing seat 41, and is fixed by a locking nut 46 and a bearing cover plate 47, and a pulley 45 is fixed on this end. The driving mechanism 40 drives the pulley 45 to rotate through the belt transmission mechanism, so that the main shaft 42 rotates, and drives the rotor 20 to rotate in the reaction chamber 11. When there is a slurry containing ball milling beads in the reaction chamber 11, the high-speed rotation of the rotor 20 can strongly stir the slurry, so that the slurry can undergo a mechanochemical reaction under the action of the ball milling beads; a large amount of heat will be generated in the process, and the heat can be taken away by cooling water.

[0054] Example 1

[0055] S1, add 75g FeS, 75g FeS2, 30g zero-valent iron powder and 300ml anhydrous ethanol into a container and stir for 30min to form a slurry to be ground, wherein the zero-valent iron content in the zero-valent iron powder is ≥98.5%, and the initial particle size of the zero-valent iron powder is 3.1 μm.

[0056] S2, loading zirconia beads with a weight of 0.75 kg and a diameter of 0.3 mm as grinding beads in a wet ball mill, adding the slurry to be ground into the wet ball mill for grinding to obtain slurry, the grinding temperature is 10°C, and the rotation speed of the wet ball mill is 2000 rpm.

[0057] S3, taking out slurry samples when the grinding time reaches 10 min, 40 min, 160 min, 320 min and 640 min respectively, placing each slurry sample into a magnetic separation device for separation, collecting the ground zero-valent iron particles respectively and washing them with anhydrous ethanol.

[0058] S4, placing the washed zero-valent iron particles in a vacuum drying oven and drying them at a temperature of 20°C.

[0059] Figure 6The figures are scanning electron microscope images of zero-valent iron ball-milled for 40 minutes and 640 minutes in Example 1 of the present invention and a distribution diagram of particle sizes based on SEM and image pro software statistics.

[0060] like Figure 6 As shown in the figure, after 40 minutes of ball milling, the zero-valent iron particles were mainly concentrated in the range of 1.0-1.5 µm and 0.5-1.0 µm, accounting for 34.6% and 39.1%, respectively. After 640 minutes of ball milling, the particle size was further reduced, mainly concentrated in the range of 0.0-0.5 µm, accounting for 42.4%, indicating that the ball milling time had a significant effect on further refining the particles.

[0061] Figure 7 1 and 2 are electron microscope images and element distribution diagrams of particles of zero-valent iron after ball milling for 40 minutes and 640 minutes in Example 1 of the present invention.

[0062] like Figure 7 As shown in the figure, the purple dots represent iron elements, and the green dots represent sulfur elements. When zero-valent iron is ball-milled for 40 minutes, sulfides are evenly covered on the surface of zero-valent iron particles. When ball-milled for 640 minutes, the coverage of sulfides is further increased, and the sulfide layer on the particle surface is more uniform, further indicating the importance of ball-milling time to the sufficiency and uniformity of the sulfidation reaction.

[0063] Figure 8 This is a crystal phase microscope image of zero-valent iron after ball milling for 640 minutes in Example 1 of the present invention.

[0064] like Figure 8 As shown in Figure 1, (A) shows the overall morphology of zero-valent iron particles, where multiple cracks and fracture areas can be observed. These areas are formed due to mechanical stress during ball milling. These cracks are FeS x The embedding of the particles provides a path, indicating that the zero-valent iron undergoes significant plastic deformation and fracture during the ball milling process. (B) is an enlarged view of (A) showing the FeS x Distribution of particles in zero-valent iron particles. The purple area in the figure represents FeS x particles, the green area represents the iron element. It can be seen that FeS x The particles are embedded in the cracks of zero-valent iron and are distributed inside the particles as these cracks extend.

[0065] Fig. 9 It is the removal capacity of Cr(VI) after 640 minutes of zero-valent iron ball milling in Example 1 of the present invention.

[0066] like Fig. 9As shown in the figure, the initial concentration of Cr(VI) was 10 mg / L, and then 10 mg / L of Cr(VI) was added at intervals for a total of six additions. The iron concentration was 1 g / L, and the vertical axis shows the percentage change of Cr(VI) concentration relative to the initial concentration (C t / C0).

[0067] From the first to the third addition:

[0068] After the first few additions of Cr(VI), ZVI was able to quickly reduce the Cr(VI) concentration to almost zero. This indicates that in the initial stage, ZVI has a high reducing power and can effectively remove 10 mg / L Cr(VI) per addition.

[0069] From the fourth to the fifth addition:

[0070] With the continuous addition of Cr(VI), the removal efficiency of zero-valent iron began to decline, especially after the fourth and fifth additions, the removal rate of Cr(VI) decreased, but it could still significantly reduce the concentration of Cr(VI). This shows that the reduction ability of zero-valent iron is gradually consumed, but it still has a strong removal ability.

[0071] The sixth addition:

[0072] After the sixth addition, the removal efficiency of Cr(VI) decreased significantly and the concentration of Cr(VI) showed an upward trend. This indicates that the reduction activity of zero-valent iron is almost exhausted and can no longer effectively remove the newly added Cr(VI), resulting in the accumulation of Cr(VI) in the solution.

[0073] Removal capacity calculation: As can be seen from the figure, during the first five additions, zero-valent iron was able to successfully remove 10 mg / L Cr(VI) each time, indicating that the removal capacity of zero-valent iron is at least 50 mg-Cr(VI) / g-ZVI. At the sixth addition, the removal efficiency dropped significantly, indicating that the removal capacity of zero-valent iron is close to saturation.

[0074] Comparative Example 1

[0075] S1, adding zero-valent iron powder to alcohol, stirring thoroughly to form a slurry to be ground, the content of zero-valent iron in the zero-valent iron powder is 98.8%, and the median particle size of the zero-valent iron particles is 3.1 microns.

[0076] S2, loading zirconia beads with a weight of 0.75 kg and a diameter of 0.3 mm as grinding beads in a wet ball mill, adding the slurry to be ground into the wet ball mill for grinding to obtain slurry, the grinding temperature is 10°C, and the rotation speed of the wet ball mill is 2000 rpm.

[0077] S3, taking out slurry samples when the grinding time reaches 10 min, 40 min, 160 min, 320 min and 640 min respectively, placing each slurry sample into a magnetic separation device for separation, collecting the ground zero-valent iron particles respectively and washing them with anhydrous ethanol.

[0078] S4, placing the washed zero-valent iron particles in a vacuum drying oven and drying them at a temperature of 20°C.

[0079] Fig.10 These are scanning electron microscope images of zero-valent iron ball milled for 10 minutes, 40 minutes, and 640 minutes in Comparative Example 1 of the present invention.

[0080] like Fig.10 As shown in the figure, after 10 minutes of grinding, the zero-valent iron particles underwent initial plastic deformation, but the overall morphology of the particles did not change much and remained relatively large. The measurement showed that the size of the particles was about 2.73 microns to 4.22 microns, the surface was relatively rough, and the particle morphology still appeared to be large, loose blocks.

[0081] After 40 minutes of grinding, the shape of the zero-valent iron particles gradually changed into flakes, and the size increased slightly to 4.70 microns and 4.13 microns. This shows that during the long ball milling process, the zero-valent iron particles are prone to cold welding, and the particles re-aggregate into larger flake structures, resulting in unsatisfactory crushing effects.

[0082] After 640 minutes of long grinding, the average particle size of the particles ranged from 3.03 microns to 2.96 microns, showing further development of the flaky structure. However, the particle size was still large, and the morphology tended to be flaky, thin and wide, indicating that the pulverization efficiency of zero-valent iron was low and it could not be effectively pulverized to a smaller particle size by mechanical force alone.

[0083] The enlarged image after 640 minutes of ball milling shows that after 640 minutes of grinding, the size of some zero-valent iron particles is 2.34 microns to 2.52 microns. These particles still have a flaky structure and a relatively smooth surface. There is still a certain cold welding phenomenon between the particles, and a significant nano-scale crushing effect cannot be achieved.

[0084] Fig.11 1 is the removal curve of Cr(VI) by Example 1 of the present invention, Comparative Example 1 and the original iron powder.

[0085] like Fig.11 As shown, the zero-valent iron concentration used in the experiment was 1 g / L and the initial concentration of hexavalent chromium (Cr(VI)) was 10 mg / L.

[0086] The three curves in the figure correspond to the removal effect of Cr(VI) on untreated original iron powder, zero-valent iron ball-milled in alcohol, and zero-valent iron ball-milled in alcohol using FeS and FeS2 as additives.

[0087] Original iron powder (blue squares): Original iron powder has a relatively weak effect on the removal of Cr(VI). After 30 minutes of reaction, the concentration of Cr(VI) is reduced to about 60%. The removal rate of Cr(VI) is slow in the early stage of the reaction (0-10 minutes), which indicates that the original iron powder has a low reactivity, which may be caused by the larger particle size and smaller specific surface area.

[0088] Ball-milled zero-valent iron in alcohol (pink dots): The removal of Cr(VI) by ball-milled zero-valent iron in alcohol was significantly improved, especially in the first 10 minutes of the reaction, when the removal rate of Cr(VI) was significantly accelerated. After 30 minutes of reaction, the concentration of Cr(VI) decreased to about 40%. This indicates that ball milling significantly increased the reactivity of zero-valent iron, probably due to particle refinement and increased specific surface area during the ball milling process.

[0089] Zero-valent iron milled with FeS and FeS2 (green diamonds): Zero-valent iron milled in alcohol with FeS and FeS2 as additives showed the strongest Cr(VI) removal ability. In just 5 minutes, the concentration of Cr(VI) dropped rapidly to about 20%, and within 30 minutes, Cr(VI) was almost completely removed, with the concentration close to zero. This result shows that the FeS and FeS2 additives significantly enhanced the reactivity of zero-valent iron, not only accelerating the reduction reaction rate of Cr(VI), but also improving the thoroughness of the reaction.

[0090] Fig.12 It is the transmission performance of Example 1 and Comparative Example 1 of the present invention and the original iron powder in the porous medium.

[0091] like Fig.12 , including a schematic diagram of the experimental device, shows a typical sand column experimental device for studying the transport properties of zero-valent iron particles in porous media. The sand column is 30 cm long and 2 cm in diameter.

[0092] A peristaltic pump was used to pump the suspension containing zero-valent iron into the column from the bottom at a flow rate of 10 mL / min. The liquid flowed through the sand layer and flowed out from the top.

[0093] Agitation and mixing: The suspension was kept uniformly dispersed in the flask by mechanical stirring (200 rpm) before entering the sand column to ensure uniform distribution of the zero-valent iron particles in the fluid.

[0094] The transmission performance of zero-valent iron in the sand column:

[0095] Original iron powder: The left column is filled with a suspension of original zero-valent iron (without any ball milling treatment). The experiment shows that the original zero-valent iron has the worst transmission performance, and the black zero-valent iron particles are almost completely retained at the bottom of the column, with a transmission height of only 14.8 cm. The particle size is large (3083 nanometers), which makes it difficult to effectively migrate in the sand column, indicating that its transmission ability in porous media is weak.

[0096] Iron powder ball-milled in alcohol for 640 minutes: The middle column is filled with zero-valent iron that has been ball-milled for 640 minutes and treated in alcohol. Compared with the original iron powder, the zero-valent iron ball-milled in alcohol shows a certain degree of transport improvement, with the transport height increased to 26.8 cm. However, its transport performance is still not ideal, mainly because its particle size is still large (3342 nm), which hinders effective diffusion in the sand layer.

[0097] Iron powder milled with FeS and FeS2 for 640 min: The column on the right is filled with zero-valent iron after milling with FeS and FeS2 for 640 minutes. The zero-valent iron under this treatment condition shows significantly better transport properties, almost filling the entire sand column (transport height is close to 30 cm). In addition, the particle size is significantly reduced to 600 nanometers (measured by zeta potential instrument), making it easier to diffuse and transport in the sand layer.

[0098] Summary and analysis: The comparison of transport performance, the experimental results clearly show that the transport performance of zero-valent iron is closely related to its particle size. The smaller the particle size, the better the transport effect of zero-valent iron in porous media. The original iron powder is almost impossible to transport in the sand column due to its large particle size; the zero-valent iron ball-milled in alcohol has some improvement, but it is still not ideal; and the zero-valent iron ball-milled with FeS and FeS2 has the best transport performance due to the significantly reduced particle size.

[0099] The role of FeS and FeS2 As ball milling aids, FeS and FeS2 not only significantly improve the pulverization effect of zero-valent iron (reduce particle size), but also enhance its transport capacity in porous media. This is of great significance for practical applications, especially in environmental remediation projects that require particles to migrate in groundwater or soil. The use of this modified zero-valent iron can greatly improve the remediation efficiency.

[0100] Potential for application in environmental remediation: Zero-valent iron co-milled with FeS and FeS2 is more suitable for environmental remediation, such as groundwater pollution control, because of its better transmission performance and reaction activity. The good transmission capacity in porous media means that this zero-valent iron can reach the pollution source more effectively for deep remediation.

[0101] Comparative Example 2

[0102] Based on the experimental steps of Example 1, 75 g FeS and 75 g FeS2 were replaced with an equal mass of sodium sulfide.

[0103] Comparative Example 3

[0104] Based on the experimental steps of Example 1, 75 g FeS and 75 g FeS2 were replaced with an equal mass of sodium thiosulfate.

[0105] Comparative Example 4

[0106] Based on the experimental steps of Example 1, 75 g FeS and 75 g FeS2 were replaced with an equal mass of thiourea.

[0107] Comparative Example 5

[0108] Based on the experimental steps of Example 1, 75 g FeS and 75 g FeS2 were replaced by sulfur of equal mass.

[0109] Fig.13 It is a line graph of ball milling time and average particle size of Example 1 of the present invention and Comparative Examples 2-5.

[0110] like Fig.13 As shown, when the iron sulfide in Example 1 is used as a ball milling aid, the ball milling effect is the best, and the average particle size is significantly reduced. The sodium sulfide in Comparative Example 2 has the second best effect. The sodium thiosulfate, thiourea and sulfur in Comparative Examples 3-5 have poor effects, and the average particle size after ball milling is less reduced.

[0111] Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for crushing zero-valent iron, characterized in that: include: S1, adding FeS, FeS2, zero-valent iron powder and anhydrous ethanol into a container and stirring evenly to form a slurry to be ground, wherein the mass ratio of FeS to FeS2 is 1:(0.9-1.1), and the mass ratio of the mixture of FeS and FeS2 to the zero-valent iron powder is 1:(0.15-0.25); S2, loading grinding beads into a wet ball mill, adding the slurry to be ground into the wet ball mill for grinding to obtain slurry, the grinding time is 10-640 min; S3, taking out the slurry from the wet ball mill, placing the slurry into a magnetic separation device for separation, collecting the ground zero-valent iron particles and washing them with anhydrous ethanol; as well as S4, placing the washed zero-valent iron particles in a vacuum drying oven and drying them at a temperature below 40°C.

2. The method for crushing zero-valent iron according to claim 1, characterized in that: in, The diameters of the FeS and FeS2 are both 50-60 μm.

3. The method for crushing zero-valent iron according to claim 1, characterized in that: in, The stirring time is 20-50 min.

4. The method for crushing zero-valent iron according to claim 1, characterized in that: in, The content of zero-valent iron in the zero-valent iron powder is higher than 98.5%, and the median particle size of the zero-valent iron powder is 3.0-3.2 microns.

5. The method for crushing zero-valent iron according to claim 1, characterized in that: in, The grinding beads are zirconium oxide beads with a weight of 0.7-0.8 kg and a diameter of 0.2-0.4 mm.

6. The method for crushing zero-valent iron according to claim 1, characterized in that: in, During the grinding process, the temperature in the cavity of the wet ball mill is controlled at 8-12°C.

Images