Method for preparing electromagnetic wave absorbing material by utilizing fine coal gasification slag and electromagnetic wave absorbing material prepared by method

Abstract

The invention provides a method for preparing an electromagnetic wave absorbing material by utilizing fine coal gasification slag and the electromagnetic wave absorbing material prepared by the method, and belongs to the technical field of solid waste resource utilization. According to the invention, the coal gasification fine slag is used as a raw material, magnetic Fe3O4 is separated by using separation technologies such as flotation and magnetic separation, and the magnetic Fe3O4 is used as a raw material, so that the compounding of the magnetic Fe3O4 and polyaniline is realized in an acidic environment provided by hydrochloric acid, and the electromagnetic wave absorption performance of the composite material is improved; according to the method provided by the invention, the effective components of the coal gasification fine slag are utilized to the greatest extent, the economic utilization value of the coal gasification fine slag is effectively improved, the resource reutilization of solid wastes is realized, the environmental pollution is reduced, meanwhile, the raw material cost is low, and the market competitiveness of the product is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste resource utilization, and particularly to a method for preparing an electromagnetic wave absorbing material by using fine slag from coal gasification and the prepared electromagnetic wave absorbing material. Background Art

[0002] With the development of the coal chemical industry, the discharge of fine slag from coal gasification is increasing day by day. It is urgent to find a simple and high-value application method for the fine slag from coal gasification. The fine slag from coal gasification mainly consists of unburned residual carbon, inorganic ash such as SiO2, Al2O3, CaO, and Fe3O4. Among them, the residual carbon not only has a high specific surface area and a developed pore structure and can be used as an adsorption material, an electrode material, a catalyst carrier, etc. Substances such as SiO2, Al2O3, and CaO contained in the inorganic ash are common reinforcing fillers for rubber and plastics; magnetic Fe3O4 can be used as an electromagnetic wave absorbing material. However, magnetic Fe3O4 has technical bottlenecks such as difficult regulation of dielectric loss and limited absorption bandwidth, which seriously restricts its practical application in the field of wave-absorbing materials.

[0003] Therefore, how to efficiently utilize the Fe3O4 magnetic component contained in the fine slag from coal gasification, and develop a high-performance electromagnetic wave absorbing material with characteristics of wide frequency band, strong absorption, and thin thickness through material design and structure regulation has become a key technical problem that urgently needs to be broken through in this field, and has double strategic significance for realizing the high-value utilization of industrial solid waste and the development of new functional materials. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing an electromagnetic wave absorbing material by using fine slag from coal gasification and the prepared electromagnetic wave absorbing material. The present invention realizes the reuse of solid waste from fine slag of coal gasification, and at the same time, the prepared electromagnetic wave absorbing material has excellent electromagnetic wave absorption performance.

[0005] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing an electromagnetic wave absorbing material by using fine slag from coal gasification, comprising the following steps:

[0007] (1) Mix the fine slag from coal gasification and water to obtain a slurry of fine slag from coal gasification, and then add a flotation reagent for flotation to obtain a flotation concentrate and a flotation tailing;

[0008] (2) Perform magnetic separation on the flotation tailing obtained in step (1) to obtain magnetic Fe3O4;

[0009] (3) Mix the magnetic Fe3O4, aniline, and hydrochloric acid obtained in step (2), and then add an initiator for polymerization reaction to obtain an electromagnetic wave absorbing material.

[0010] Preferably, the concentration of the fine slag slurry of coal gasification in step (1) is 10-100 g / L.

[0011] Preferably, the flotation reagents in step (1) include a collector and a frother; the collector includes kerosene, diesel oil or oleic acid; the frother includes sec-octanol, terpineol or polyethylene glycol.

[0012] Preferably, the dosage of the collector is 5000-15000 g / t; the dosage of the frother is 5000-15000 g / t.

[0013] Preferably, the magnetic separation in step (2) is wet magnetic separation.

[0014] Preferably, the concentration of hydrochloric acid in step (3) is 0.05-0.15 mol / L.

[0015] Preferably, the mass ratio of magnetic Fe3O4, the volume of aniline and the volume of hydrochloric acid in step (3) is (40-55) mg:(100-300) μL:(80-120) mL.

[0016] Preferably, the initiator in step (3) is an ammonium persulfate solution; the concentration of the ammonium persulfate solution is 0.01-0.05 g / mL; the volume ratio of aniline to the initiator is (100-300) μL:20 mL.

[0017] Preferably, the polymerization reaction in step (3) is carried out under the condition of an ice-water bath; the time of the polymerization reaction is 2-6 h.

[0018] The present invention provides an electromagnetic wave absorbing material prepared by the method according to the above technical solution.

[0019] The present invention provides a method for preparing an electromagnetic wave absorbing material using fine slag from coal gasification, comprising the following steps: (1) mixing the fine slag from coal gasification and water to obtain a fine slag slurry from coal gasification, then adding a flotation reagent for flotation to obtain a flotation concentrate and a flotation tailing; (2) subjecting the flotation tailing obtained in step (1) to magnetic separation to obtain magnetic Fe3O4; (3) mixing the magnetic Fe3O4 obtained in step (2), aniline, and hydrochloric acid, and then adding an initiator for polymerization reaction to obtain an electromagnetic wave absorbing material. The present invention uses the fine slag from coal gasification as a raw material, utilizes separation technologies such as flotation and magnetic separation to separate magnetic Fe3O4, and uses magnetic Fe3O4 as a raw material to realize the composite of magnetic Fe3O4 and polyaniline in an acidic environment provided by hydrochloric acid, improving the electromagnetic wave absorption performance of the composite material; the method provided by the present invention maximally utilizes the effective components of the fine slag from coal gasification, effectively improves the economic utilization value of the fine slag from coal gasification, realizes the resource recycling of solid waste, reduces environmental pollution, and at the same time has a low raw material cost and improves the market competitiveness of the product. The results of the examples show that the electromagnetic wave absorbing material prepared by the method provided by the present invention has better electromagnetic wave absorption performance, with a minimum reflection loss value of -37.98 dB, a matching thickness of 2.00 mm, and also has a maximum effective absorption bandwidth of 4.94 GHz. Description of the Drawings

[0020] Figure 1 Schematic flow chart for preparing an electromagnetic wave absorbing material in Example 1;

[0021] Figure 2 Morphology diagrams of magnetic Fe3O4 obtained in step (2) of Example 5 at different magnifications;

[0022] Figure 3 EDS diagram of magnetic Fe3O4 obtained in step (2) of Example 5;

[0023] Figure 4 Scanning electron microscope diagrams of the electromagnetic wave absorbing material prepared in Example 5 at different magnifications;

[0024] Figure 5 Mapping diagram of the electromagnetic wave absorbing material prepared in Example 5;

[0025] Figure 6 Three-dimensional RL diagram of the electromagnetic wave absorbing material prepared in Example 2;

[0026] Figure 7 Contour diagram of the electromagnetic wave absorbing material prepared in Example 2;

[0027] Figure 8 Three-dimensional RL diagram of the electromagnetic wave absorbing material prepared in Example 5;

[0028] Figure 9 Contour map of the electromagnetic wave absorption material prepared in Example 5;

[0029] Figure 10 3D RL map of the electromagnetic wave absorption material prepared in Example 6;

[0030] Figure 11 Contour map of the electromagnetic wave absorption material prepared in Example 6;

[0031] Figure 12 3D RL map of the polyaniline material prepared in Comparative Example 1;

[0032] Figure 13 Contour map of the polyaniline material prepared in Comparative Example 1. Detailed implementation manners

[0033] The present invention provides a method for preparing an electromagnetic wave absorption material by using fine slag from coal gasification, comprising the following steps:

[0034] (1) Mix the fine slag from coal gasification and water to obtain a fine slag slurry from coal gasification, and then add a flotation reagent for flotation to obtain a flotation concentrate and a flotation tailing;

[0035] (2) Perform magnetic separation on the flotation tailing obtained in step (1) to obtain magnetic Fe3O4;

[0036] (3) Mix the magnetic Fe3O4, aniline and hydrochloric acid obtained in step (2), and then add an initiator for a polymerization reaction to obtain an electromagnetic wave absorption material.

[0037] The present invention mixes the fine slag from coal gasification and water to obtain a fine slag slurry from coal gasification, and then adds a flotation reagent for flotation to obtain a flotation concentrate and a flotation tailing.

[0038] The present invention does not impose special limitations on the specific source of the gasification fine slag, and the gasification fine slag well-known to those skilled in the art can be used. As an embodiment of the present invention, the gasification fine slag can come from Zhong'an United Coal Chemical Co., Ltd. As an embodiment of the present invention, the gasification fine slag can include water, unburned carbon and ash; the moisture content of the gasification fine slag can be 25-30 wt.%, and can also be 28-30 wt.%. As an embodiment of the present invention, based on the total mass of unburned carbon and ash in the gasification fine slag being 100%, it can include 15-25% of unburned carbon and 75-85% of ash, and can also be 21.53% of unburned carbon and 78.47% of ash. In the present invention, based on the mass percentage of ash being 100%, the composition of the ash can be: SiO2: 52.80%, Al2O3: 19.07%, Fe2O3 and Fe3O4: 7.46%, CaO: 10.12%, K2O: 2.59%, TiO2: 2.32%, P2O5: 0.78%, MgO: 0.52%, SO3: 0.96% and the balance of impurities.

[0039] In the present invention, the gasification fine slag is preferably ball-milled first and then mixed with water. In the present invention, the ball-to-material ratio of the ball milling is preferably 10:(0.5-2); the rotation speed of the ball milling is preferably 100-200 r / min; the time of the ball milling is preferably 0.5-2 h; the ball milling is preferably carried out in a ball mill. As an embodiment of the present invention, the ball-to-material ratio of the ball milling can be 10:1; the rotation speed of the ball milling can be 150 r / min; the time of the ball milling can be 1-1.5 h. By ball milling in the present invention, the particle size of the gasification fine slag can be refined, and at the same time, it is beneficial to separate the residual carbon and other inorganic components in the gasification fine slag, thus facilitating subsequent flotation separation.

[0040] The present invention does not impose special limitations on the dosage relationship between the gasification fine slag and water, which is determined according to the common technical knowledge of those skilled in the art, as long as the concentration of the gasification fine slag slurry meets the requirements.

[0041] The present invention does not impose special limitations on the mixing method of the gasification fine slag and water, as long as they can be mixed evenly.

[0042] In the present invention, the concentration of the gasification fine slag slurry is preferably 10-100 g / L. As an embodiment of the present invention, the concentration of the gasification fine slag slurry can be 10 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L or 100 g / L. By controlling the concentration of the gasification fine slag slurry in the present invention, it can have good fluidity, be convenient to mix evenly with flotation reagents, and thus be beneficial to improving the flotation effect.

[0043] In the present invention, the flotation reagent preferably comprises a collector and a foaming agent. In the present invention, the collector preferably comprises kerosene, diesel oil or oleic acid; the foaming agent preferably comprises sec-octanol, terpineol or polyethylene glycol. In the present invention, the dosage of the collector is preferably 5000-15000 g / t; the dosage of the foaming agent is preferably 5000-15000 g / t. In the present invention, the dosages of the collector and the foaming agent are based on the mass of the fine slag slurry of coal gasification. In the present invention, the mass ratio of the collector to the foaming agent is preferably 1:(0.5-1.5), more preferably 1:1. As an embodiment of the present invention, the dosage of the collector can be 5000 g / t, 6000 g / t, 7000 g / t, 8000 g / t, 9000 g / t, 10000 g / t, 11000 g / t, 12000 g / t, 13000 g / t, 14000 g / t or 15000 g / t; the dosage of the foaming agent can be 5000 g / t, 6000 g / t, 7000 g / t, 8000 g / t, 9000 g / t, 10000 g / t, 11000 g / t, 12000 g / t, 13000 g / t, 14000 g / t or 15000 g / t. By adding the collector and the foaming agent, the present invention can separate the ash and unburned carbon in the fine slag of coal gasification, thus facilitating subsequent magnetic separation and adsorption.

[0044] In the present invention, the flotation is preferably carried out in a flotation machine. The present invention has no special limitation on the specific model and source of the flotation machine, and a commercially available flotation machine well-known to those skilled in the art can be used. As an embodiment of the present invention, the flotation machine can be a single-tank flotation machine.

[0045] In the present invention, the operation of adding the flotation reagent for flotation is preferably: stirring the fine slag slurry of coal gasification for 1-5 min, then adding the collector and reacting for 30-120 s, then adding the foaming agent, and opening the air valve of the flotation machine for aeration after 5-30 s. When bubbles appear, scrape the foam and collect the foam concentrate. More preferably: stirring the fine slag slurry of coal gasification for 3-4 min, then adding the collector and reacting for 60-90 s, then adding the foaming agent, and opening the air valve of the flotation machine for aeration after 10-15 s. When bubbles appear, scrape the foam and collect the foam concentrate.

[0046] After obtaining the flotation concentrate and the flotation tailings, the present invention performs magnetic separation on the flotation tailings to obtain magnetic Fe3O4.

[0047] In the present invention, the magnetic separation is preferably wet magnetic separation; the operation of the wet magnetic separation is preferably as follows: mixing the flotation tailings and water to obtain a flotation tailings slurry with a concentration of 50 - 100 g / L, turning on the power of the magnetic separation tube, adjusting the magnetic field intensity to 100 - 300 mT, adding water in the glass tube to a height of 8 cm from the tube mouth, adjusting the water flow rate to 1 - 3 cm / s, starting the motor to start swinging, and then adding the flotation tailings slurry into the feeding funnel. The magnetic particles in the flotation tailings slurry are adsorbed on the inner wall of the tube near the magnetic pole, and the non-magnetic part is discharged from the lower part of the glass tube along with the flushing water. Collect the primary flushing waste liquid for re-magnetic separation, and repeat the above operation until the water in the glass tube is clear and transparent. Then turn off the motor and slowly discharge the waste water in the tube. As an embodiment of the present invention, the concentration of the flotation tailings slurry can be 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L or 100 g / L; the magnetic field intensity can be 100 mT, 150 mT, 200 mT, 250 mT or 300 mT; the water flow rate can be 1 cm / s, 1.5 cm / s, 2 cm / s, 2.5 cm / s or 3 cm / s. By the above method, the present invention can improve the recovery rate of magnetic Fe3O4.

[0048] The present invention preferably dries the magnetic substance obtained by magnetic separation to obtain magnetic Fe3O4. The present invention has no special limitation on the temperature and time of the drying, which is determined according to the common technical knowledge of those skilled in the art until the magnetic substance reaches a constant weight. The present invention can remove the residual moisture by drying.

[0049] After obtaining magnetic Fe3O4, the present invention mixes the magnetic Fe3O4, aniline and hydrochloric acid, and then adds an initiator to carry out a polymerization reaction to obtain an electromagnetic wave absorbing material.

[0050] In the present invention, the concentration of the hydrochloric acid is preferably 0.05 - 0.15 mol / L, more preferably 0.1 mol / L. In the present invention, the mass ratio of the magnetic Fe3O4, the volume of aniline and the volume of hydrochloric acid is preferably (40 - 55) mg : (100 - 300) μL : (80 - 120) mL, more preferably 51 mg : (100 - 300) μL : 100 mL. As an embodiment of the present invention, the mass ratio of the magnetic Fe3O4, the volume of aniline and the volume of hydrochloric acid can be 51 mg : 100 μL : 100 mL, 51 mg : 150 μL : 100 mL, 51 mg : 200 μL : 100 mL, 51 mg : 250 μL : 100 mL or 51 mg : 300 μL : 100 mL.

[0051] In the present invention, the preferred way of mixing the magnetic Fe3O4, aniline and hydrochloric acid is to mix the magnetic Fe3O4 and hydrochloric acid and then perform ultrasonic treatment, and then dropwise add aniline. The present invention has no special limitation on the power and time of the ultrasonic treatment, which is determined according to the common technical knowledge of those skilled in the art, as long as the magnetic Fe3O4 can be evenly dispersed. As an embodiment of the present invention, the time of the ultrasonic treatment can be 20 - 60 min, and can also be 30 - 40 min. The present invention has no special limitation on the dropping rate of the aniline, which is determined according to the common technical knowledge of those skilled in the art, as long as it can be evenly dispersed in hydrochloric acid.

[0052] In the present invention, the initiator is preferably an ammonium persulfate solution; the concentration of the ammonium persulfate solution is preferably 0.01 - 0.05 g / mL; the volume ratio of the aniline to the initiator is preferably (100 - 300) μL:20 mL. As an embodiment of the present invention, the concentration of the ammonium persulfate solution can be 0.01 g / mL, 0.015 g / mL, 0.02 g / mL, 0.025 g / mL, 0.03 g / mL, 0.035 g / mL, 0.04 g / mL, 0.045 g / mL or 0.05 g / mL; the volume ratio of the aniline to the initiator can be 100 μL:20 mL, 150 μL:20 mL, 200 μL:20 mL, 250 μL:20 mL or 300 μL:20 mL. By adding an initiator in the present invention, the polymerization reaction can be promoted.

[0053] In the present invention, the preferred way of adding the initiator is dropwise addition. The present invention has no special limitation on the dropping rate, which can be determined according to the common technical knowledge of those skilled in the art.

[0054] In the present invention, the polymerization reaction is preferably carried out under the condition of an ice-water bath; the time of the polymerization reaction is preferably 2 - 6 h; the polymerization reaction is preferably carried out under stirring conditions. The present invention has no special limitation on the stirring rate, which is determined according to the common technical knowledge of those skilled in the art, as long as the solution splashing can be avoided and the components can be evenly mixed. As an embodiment of the present invention, the time of the polymerization reaction can be 2 h, 3 h, 4 h, 5 h or 6 h.

[0055] The present invention preferably further includes washing and drying the product of the polymerization reaction to obtain an electromagnetic wave absorbing material.

[0056] In the present invention, the washing is preferably carried out by alternately washing with deionized water and alcohol. The present invention has no special limitation on the number of times of alternately washing with deionized water and alcohol, which is determined according to the common technical knowledge of those skilled in the art, as long as the impurities can be removed.

[0057] In the present invention, the drying temperature is preferably 50 - 80 °C; the drying time is preferably 8 - 16 h; and the drying is preferably carried out in an oven. As an embodiment of the present invention, the drying temperature can be 50 °C, 60 °C, 70 °C or 80 °C; and the drying time can be 8 h, 10 h, 12 h, 14 h or 16 h. Through drying, the present invention can remove residual moisture and alcohol to obtain a dried electromagnetic wave absorbing material.

[0058] The present invention uses fine coal gasification slag as a raw material, and through separation techniques such as flotation and magnetic separation, magnetic Fe3O4 is separated out. Using the magnetic Fe3O4 as a raw material, the composite of magnetic Fe3O4 and polyaniline is realized in an acidic environment provided by hydrochloric acid, improving the electromagnetic wave absorption performance of the composite material. The method provided by the present invention makes the most of the effective components of fine coal gasification slag, effectively improves the economic utilization value of fine coal gasification slag, realizes the resource recycling of solid waste, reduces environmental pollution, and at the same time has low raw material costs, improving the market competitiveness of the product.

[0059] The present invention also provides an electromagnetic wave absorbing material prepared by the method according to the above technical solution. In the present invention, the electromagnetic wave absorbing material is preferably an Fe3O4 / polyaniline composite material.

[0060] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope protected by the present invention.

[0061] The fine coal gasification slag used in the examples and comparative examples all comes from Zhong'an United Coal Chemical Co., Ltd., and its moisture content is about 30 wt.%. Calculated based on the total mass of unburned carbon and ash in the fine coal gasification slag being 100%, the unburned carbon is 21.53% and the ash is 78.47%. Calculated based on the mass percentage of ash being 100%, the composition of the ash is: SiO2: 52.80%, Al2O3: 19.07%, Fe2O3 and Fe3O4: 7.46%, CaO: 10.12%, K2O: 2.59%, TiO2: 2.32%, P2O5: 0.78%, MgO: 0.52%, SO3: 0.96% and the remaining impurities.

[0062] Example 1

[0063] A method for preparing an electromagnetic wave absorbing material using fine coal gasification slag, comprising the following steps:

[0064] (1) First, pulverize the gasification fine slag in a ball mill with a ball-to-material ratio of 10:1, a rotation speed of 150 r / min, and a milling time of 1 h. Then mix it with water to obtain a gasification fine slag slurry with a concentration of 60 g / L. Place the gasification fine slag slurry in a 1.5 L single-tank flotation machine and stir for 3 min. Then add kerosene and react for 60 s with a kerosene dosage of 8000 g / t. Next, add sec-octanol with a dosage of 8000 g / t. After 10 s, open the air valve of the flotation machine for aeration. When bubbles appear, scrape the foam and collect the foam concentrate to obtain flotation concentrate and flotation tailings;

[0065] (2) Mix the flotation tailings obtained in step (1) with water to obtain a flotation tailings slurry with a concentration of 50 g / L. Turn on the power of the magnetic separation tube, adjust the magnetic field strength to 200 mT, add water to the glass tube up to 8 cm from the tube mouth, adjust the water flow rate to 2 cm / s. After starting the motor to swing, add the flotation tailings slurry to the feeding funnel. The magnetic particles in the flotation tailings slurry are adsorbed on the inner wall of the tube near the magnetic pole, and the non-magnetic part is discharged from the lower part of the glass tube with the washing water. Collect the first washing waste liquid and perform magnetic separation again. Repeat the above operation until the water in the glass tube is clear and transparent. Turn off the motor, slowly drain the wastewater in the tube, and dry the magnetic substances on the inner wall of the tube to obtain magnetic Fe3O4;

[0066] (3) Mix the magnetic Fe3O4 obtained in step (2) with hydrochloric acid and perform ultrasonic treatment for 30 min. Then add aniline dropwise, and then add the initiator. Conduct a polymerization reaction in an ice-water bath for 4 h, and continuously perform mechanical stirring during the polymerization reaction. Finally, wash alternately with deionized water and alcohol and dry in an oven at 60 °C for 12 h to obtain an electromagnetic wave absorption material, denoted as Fe3O4@PANI; the concentration of the hydrochloric acid is 0.1 mol / L; the mass ratio of the magnetic Fe3O4, the volume of aniline, and the volume of hydrochloric acid is 51 mg:100 μL:100 mL; the initiator is an ammonium persulfate solution with a concentration of 0.015 g / mL, and the volume ratio of aniline to the initiator is 100 μL:20 mL.

[0067] The process flow diagram for preparing the electromagnetic wave absorption material in Example 1 is as Figure 1 shown. It can be Figure 1 seen that in the present invention, the gasification fine slag is used as a raw material. After flotation, the flotation tailings are subjected to magnetic separation to obtain magnetic Fe3O4. Then, using magnetic Fe3O4 as a raw material, under the condition of an ice-water bath, with hydrochloric acid as a solvent, aniline as a polymer monomer, and ammonium persulfate as an initiator, through a polymerization reaction, the composite of magnetic Fe3O4 and polyaniline is realized, and Fe3O4@PANI is obtained.

[0068] Example 2

[0069] A method for preparing an electromagnetic wave absorbing material using fine slag from coal gasification, comprising the following steps:

[0070] (1) First, ball-mill the fine slag from coal gasification in a ball mill with a ball-to-material ratio of 10:1, a rotation speed of 150 r / min, and a ball-milling time of 1 h. Then mix it with water to obtain a coal gasification fine slag slurry with a concentration of 60 g / L. Place the coal gasification fine slag slurry in a 1.5 L single-tank flotation machine and stir for 3 min. Then add diesel and react for 60 s, with the diesel dosage being 12,000 g / t. Next, add sec-octanol with a dosage of 12,000 g / t. After 10 s, open the air valve of the flotation machine to inflate. When bubbles appear, scrape the foam and collect the foam concentrate to obtain flotation concentrate and flotation tailings;

[0071] (2) Mix the flotation tailings obtained in step (1) with water to obtain a flotation tailings slurry with a concentration of 50 g / L. Turn on the power of the magnetic separation tube, adjust the magnetic field strength to 200 mT, add water to the glass tube to a height of 8 cm from the tube mouth, adjust the water flow rate to 2 cm / s. After starting the motor to swing, add the flotation tailings slurry to the feeding hopper. The magnetic particles in the flotation tailings slurry are adsorbed on the inner wall of the tube near the magnetic pole, and the non-magnetic part is discharged from the lower part of the glass tube with the washing water. Collect the first washing waste liquid and perform magnetic separation again. Repeat the above operation until the water in the glass tube is clear and transparent. Turn off the motor, slowly drain the wastewater in the tube, and dry the magnetic substances on the inner wall of the tube to obtain magnetic Fe3O4;

[0072] (3) Mix the magnetic Fe3O4 obtained in step (2) with hydrochloric acid and perform ultrasonic treatment for 30 min. Then add aniline dropwise, and then add an initiator. Carry out a polymerization reaction in an ice-water bath for 4 h, with continuous mechanical stirring during the polymerization reaction. Finally, wash alternately with deionized water and alcohol and dry in an oven at 60 °C for 12 h to obtain an electromagnetic wave absorbing material; the concentration of the hydrochloric acid is 0.1 mol / L; the mass ratio of the magnetic Fe3O4, the volume of aniline, and the volume of hydrochloric acid is 51 mg:100 μL:100 mL; the initiator is an ammonium persulfate solution with a concentration of 0.015 g / mL, and the volume ratio of aniline to the initiator is 100 μL:20 mL.

[0073] Example 3

[0074] A method for preparing an electromagnetic wave absorbing material using fine slag from coal gasification, comprising the following steps:

[0075] (1) First, pulverize the gasification fine slag in a ball mill with a ball-to-material ratio of 10:1, a rotation speed of 150 r / min, and a milling time of 1 h. Then mix it with water to obtain a gasification fine slag slurry with a concentration of 60 g / L. Place the gasification fine slag slurry in a 1.5 L single-tank flotation machine and stir for 3 min. Then add oleic acid and react for 60 s with an oleic acid dosage of 8000 g / t. Next, add terpineol with a dosage of 8000 g / t. After 10 s, open the air valve of the flotation machine for aeration. When bubbles appear, scrape the foam and collect the foam concentrate to obtain flotation concentrate and flotation tailings;

[0076] (2) Mix the flotation tailings obtained in step (1) with water to obtain a flotation tailings slurry with a concentration of 50 g / L. Turn on the power of the magnetic separation tube, adjust the magnetic field strength to 200 mT, add water in the glass tube to 8 cm from the tube mouth, adjust the water flow rate to 2 cm / s. After starting the motor to swing, add the flotation tailings slurry to the feeding funnel. The magnetic particles in the flotation tailings slurry are adsorbed on the inner wall of the tube near the magnetic pole, and the non-magnetic part is discharged from the lower part of the glass tube with the washing water. Collect the primary washing waste liquid and perform magnetic separation again. Repeat the above operation until the water in the glass tube is clear and transparent. Turn off the motor, slowly drain the wastewater in the tube, and dry the magnetic substances on the inner wall of the tube to obtain magnetic Fe3O4;

[0077] (3) Mix the magnetic Fe3O4 obtained in step (2) with hydrochloric acid and perform ultrasonic treatment for 30 min. Then add aniline dropwise, and then add the initiator. Carry out a polymerization reaction in an ice-water bath for 4 h, and continuously perform mechanical stirring during the polymerization reaction. Finally, wash alternately with deionized water and alcohol, and dry in an oven at 60 °C for 12 h to obtain an electromagnetic wave absorption material; the concentration of the hydrochloric acid is 0.1 mol / L; the mass ratio of the magnetic Fe3O4, the volume of aniline, and the volume of hydrochloric acid is 51 mg:100 μL:100 mL; the initiator is an ammonium persulfate solution with a concentration of 0.015 g / mL, and the volume ratio of aniline to the initiator is 100 μL:20 mL.

[0078] Example 4

[0079] A method for preparing an electromagnetic wave absorption material using gasification fine slag, which comprises the following steps:

[0080] (1) First, grind the gasification fine slag in a ball mill. The ball-to-material ratio for grinding is 10:1, the rotation speed of the ball mill is 150 r / min, and the grinding time is 1 h. Then, mix it with water to obtain a gasification fine slag slurry with a concentration of 60 g / L. Place the gasification fine slag slurry in a 1.5 L single-tank flotation machine and stir for 3 min. Then, add oleic acid and react for 60 s. The dosage of oleic acid is 12,000 g / t. Next, add polyethylene glycol, and the dosage of polyethylene glycol is 12,000 g / t. After 10 s, open the air valve of the flotation machine to inflate. When bubbles appear, scrape the foam and collect the foam concentrate to obtain flotation concentrate and flotation tailings;

[0081] (2) Mix the flotation tailings obtained in step (1) with water to obtain a flotation tailings slurry with a concentration of 50 g / L. Turn on the power of the magnetic separation tube, adjust the magnetic field strength to 200 mT, add water to the glass tube up to 8 cm from the tube mouth, adjust the water flow rate to 2 cm / s. After starting the motor to swing, add the flotation tailings slurry to the feeding funnel. The magnetic particles in the flotation tailings slurry are adsorbed on the inner wall of the tube near the magnetic pole, and the non-magnetic part is discharged from the lower part of the glass tube with the washing water. Collect the first washing waste liquid and perform magnetic separation again. Repeat the above operation until the water in the glass tube is clear and transparent. Turn off the motor, slowly drain the wastewater in the tube, and dry the magnetic substances on the inner wall of the tube to obtain magnetic Fe3O4;

[0082] (3) Mix the magnetic Fe3O4 obtained in step (2) with hydrochloric acid and perform ultrasonic treatment for 30 min. Then, dropwise add aniline, and then dropwise add the initiator. Carry out a polymerization reaction in an ice-water bath for 4 h. During the polymerization reaction, continuously perform mechanical stirring. Finally, wash alternately with deionized water and alcohol and dry in an oven at 60 °C for 12 h to obtain an electromagnetic wave absorption material; the concentration of the hydrochloric acid is 0.1 mol / L; the mass ratio of the magnetic Fe3O4, the volume of aniline, and the volume of hydrochloric acid is 51 mg:100 μL:100 mL; the initiator is an ammonium persulfate solution, the concentration of the ammonium persulfate solution is 0.015 g / mL, and the volume ratio of aniline to the initiator is 100 μL:20 mL.

[0083] Evaluate the flotation results of steps (1) in Examples 1 - 4 according to the flotation perfection index in GB / T 34164 - 2017. The flotation perfection index is used to evaluate the flotation perfection degree of the same coal under different technological conditions. This index combines the concentrate grade of the flotation concentrate (the ratio of the effective component of the concentrate to the mass of the concentrate) and the recovery rate, and can comprehensively reflect the technical and economic performance of the flotation process. Its calculation formula is shown in Formula I, and the obtained results are shown in Table 1:

[0084]

[0085] In Formula I, η fFor the flotation perfection index, the unit is %; γ j For the concentrate yield of the separation, the unit is %: A y For the ash content of the feed, the unit is %; A j For the ash content of the flotation concentrate, the unit is %.

[0086] Table 1 Flotation results of steps (1) of Examples 1 to 4

[0087] Example Yield of flotation concentrate (%) Ash content of flotation concentrate (%) Flotation perfection index (%) Example 1 3.01 61.08 3.10 Example 2 18.66 67.05 12.61 Example 3 11.11 69.58 5.85 Example 4 15.19 72.24 5.60

[0088] As can be seen from Table 1, after the fine slag of coal gasification is flotated by using the method provided by the present invention, the ash content in the obtained flotation concentrate is high and the flotation perfection index is high; for the fine slag of coal gasification from the same origin, using different types of collectors and frothers as flotation reagents and controlling their addition amounts will also affect the flotation effect. When the addition amounts of the flotation reagents are the same, using oleic acid and terpineol as the flotation reagents has a better flotation effect than using kerosene and sec-octanol as the flotation reagents; at the same time, using oleic acid and polyethylene glycol as the flotation reagents, compared with using oleic acid and terpineol as the flotation reagents, although the content of the flotation concentrate increases, correspondingly, the ash content of the flotation concentrate also increases, resulting in a slight decrease in the flotation perfection index; through the comparison of Examples 1 to 4, it can be seen that when using diesel and sec-octanol as the flotation reagents, the flotation effect is the best.

[0089] Example 5

[0090] A method for preparing an electromagnetic wave absorbing material by using fine slag of coal gasification, comprising the following steps:

[0091] (1) First, ball-mill the fine slag of coal gasification in a ball mill, the ball-to-material ratio of the ball milling is 10:1, the rotation speed of the ball milling is 150 r / min, the time of the ball milling is 1 h, then mix it with water to obtain a fine slag slurry of coal gasification with a concentration of 60 g / L, place the fine slag slurry of coal gasification into a 1.5 L single-tank flotation machine and stir for 3 min, then add diesel and react for 60 s, the dosage of diesel is 12000 g / t, then add sec-octanol, the dosage of sec-octanol is 12000 g / t, open the air valve of the flotation machine to inflate after 10 s, when bubbles appear, scrape the foam and collect the foam concentrate to obtain the flotation concentrate and the flotation tailings;

[0092] (2) Mix the flotation tailings obtained in step (1) with water to obtain a flotation tailings slurry with a concentration of 50 g / L. Turn on the power of the magnetic separation tube, adjust the magnetic field strength to 200 mT, add water in the glass tube to a height of 8 cm from the tube mouth, adjust the water flow rate to 2 cm / s. After starting the motor to swing, add the flotation tailings slurry to the feeding funnel. The magnetic particles in the flotation tailings slurry are adsorbed on the inner wall of the tube near the magnetic pole, and the non-magnetic part is discharged from the lower part of the glass tube with the washing water. Collect the primary washing waste liquid and perform magnetic separation again. Repeat the above operations until the water in the glass tube is clear and transparent. Turn off the motor, slowly drain the wastewater in the tube, and dry the magnetic substance on the inner wall of the tube to obtain magnetic Fe3O4;

[0093] (3) Mix the magnetic Fe3O4 obtained in step (2) with hydrochloric acid and perform ultrasonic treatment for 30 min, then dropwise add aniline, and then dropwise add the initiator. Carry out the polymerization reaction in an ice-water bath for 4 h, and continuously carry out mechanical stirring during the polymerization reaction. Finally, wash alternately with deionized water and alcohol, and dry in an oven at 60 °C for 12 h to obtain an electromagnetic wave absorbing material; the concentration of the hydrochloric acid is 0.1 mol / L; the mass ratio of the magnetic Fe3O4, the volume of aniline, and the volume of hydrochloric acid is 51 mg: 200 μL: 100 mL; the initiator is an ammonium persulfate solution, the concentration of the ammonium persulfate solution is 0.03 g / mL, and the volume ratio of aniline to the initiator is 200 μL: 20 mL.

[0094] The morphology diagrams of the magnetic Fe3O4 obtained in step (2) of Example 5 under different magnifications and storages are as Figure 2 shown. It can be seen from Figure 2 that the shape of the magnetic Fe3O4 obtained by magnetic separation in the present invention is an irregular structure.

[0095] The EDS diagram of the magnetic Fe3O4 obtained in step (2) of Example 5 is as Figure 3 shown. It can be seen from Figure 3 that the magnetic Fe3O4 obtained by magnetic separation in the present invention has high purity, the main component is magnetic Fe3O4, and only contains a small amount of impurities such as Al, Si, and Ga.

[0096] The scanning electron microscope diagrams of the electromagnetic wave absorbing material prepared in Example 5 under different magnifications are as Figure 4 shown. It can be seen from Figure 4 that the electromagnetic wave absorbing material prepared in the present invention has more pore structures, and these pore structures significantly improve the wave absorption performance of the electromagnetic wave absorbing material.

[0097] The Mapping diagram of the electromagnetic wave absorbing material prepared in Example 5 is as Figure 5 shown. It can be seen from Figure 5It can be seen that in the magnetic wave absorption material prepared by the method provided by the present invention, Fe element, N element, O element and C element are uniformly distributed, indicating that the performance of the magnetic wave absorption material is stable.

[0098] Example 6

[0099] A method for preparing an electromagnetic wave absorption material using fine slag from coal gasification comprises the following steps:

[0100] (1) First, ball-mill the fine slag from coal gasification in a ball mill with a ball-to-material ratio of 10:1, a rotation speed of 150 r / min, and a ball-milling time of 1 h. Then mix it with water to obtain a coal gasification fine slag slurry with a concentration of 60 g / L. Place the coal gasification fine slag slurry in a 1.5 L single-tank flotation machine and stir for 3 min. Then add diesel for reaction for 60 s, with the dosage of diesel being 12000 g / t. Then add sec-octanol with a dosage of 12000 g / t. After 10 s, open the air valve of the flotation machine to inflate. When bubbles appear, scrape the foam and collect the foam concentrate to obtain flotation concentrate and flotation tailings;

[0101] (2) Mix the flotation tailings obtained in step (1) with water to obtain a flotation tailings slurry with a concentration of 50 g / L. Turn on the power of the magnetic separation tube, adjust the magnetic field strength to 200 mT, add water to the glass tube to a height of 8 cm from the tube mouth, adjust the water flow rate to 2 cm / s. After starting the motor to swing, add the flotation tailings slurry to the feeding hopper. The magnetic particles in the flotation tailings slurry are adsorbed on the inner wall of the tube near the magnetic pole, and the non-magnetic part is discharged from the lower part of the glass tube with the washing water. Collect the primary washing waste liquid and perform magnetic separation again. Repeat the above operation until the water in the glass tube is clear and transparent. Turn off the motor, slowly drain the wastewater in the tube, and dry the magnetic substances on the inner wall of the tube to obtain magnetic Fe3O4;

[0102] (3) Mix the magnetic Fe3O4 obtained in step (2) with hydrochloric acid and perform ultrasonic treatment for 30 min. Then add aniline dropwise, and then add an initiator. Carry out a polymerization reaction in an ice-water bath for 4 h, with continuous mechanical stirring during the polymerization reaction. Finally, wash alternately with deionized water and alcohol, and dry in an oven at 60 °C for 12 h to obtain an electromagnetic wave absorption material; the concentration of the hydrochloric acid is 0.1 mol / L; the mass ratio of the magnetic Fe3O4, the volume of aniline, and the volume of hydrochloric acid is 51 mg:300 μL:100 mL; the initiator is an ammonium persulfate solution with a concentration of 0.045 g / mL, and the volume ratio of aniline to the initiator is 300 μL:20 mL.

[0103] Comparative Example 1

[0104] A method for preparing a polyaniline material comprises the following steps:

[0105] The hydrochloric acid was ultrasonically treated for 30 min, then aniline was added dropwise, and then an initiator was added dropwise. The polymerization reaction was carried out in an ice-water bath for 4 h, and mechanical stirring was continuously carried out during the polymerization reaction. Finally, it was washed alternately with deionized water and alcohol and dried in an oven at 60 °C for 12 h to obtain the polyaniline material; the concentration of the hydrochloric acid was 0.1 mol / L; the volume ratio of aniline to hydrochloric acid was 200 μL:100 mL; the initiator was an ammonium persulfate solution, the concentration of the ammonium persulfate solution was 0.03 g / mL, and the volume ratio of aniline to the initiator was 200 μL:20 mL.

[0106] The electromagnetic wave absorption properties of the electromagnetic wave absorption materials prepared in Examples 2, 5, and 6 and the polyaniline material prepared in Comparative Example 1 were tested. Among them, the three-dimensional RL diagram of the electromagnetic wave absorption material prepared in Example 2 is as shown in Figure 6 shown; the contour diagram of the electromagnetic wave absorption material prepared in Example 2 is as shown in Figure 7 shown; the three-dimensional RL diagram of the electromagnetic wave absorption material prepared in Example 5 is as shown in Figure 8 shown; the contour diagram of the electromagnetic wave absorption material prepared in Example 5 is as shown in Figure 9 shown; the three-dimensional RL diagram of the electromagnetic wave absorption material prepared in Example 6 is as shown in Figure 10 shown; the contour diagram of the electromagnetic wave absorption material prepared in Example 6 is as shown in Figure 11 shown; the three-dimensional RL diagram of the polyaniline material prepared in Comparative Example 1 is as shown in Figure 12 shown; the contour diagram of the polyaniline material prepared in Comparative Example 1 is as shown in Figure 13 shown, and the obtained data results are shown in Table 2:

[0107] Table 2 Electromagnetic wave absorption properties of the electromagnetic wave absorption materials prepared in Examples 2, 5, and 6 and the polyaniline material prepared in Comparative Example 1

[0108] Example <![CDATA[RL min / dB]]> f / GHz h / mm EAB / GHz Example 2 -33.08 14.80 2.68 2.32 Example 5 -37.98 12.08 2.00 4.94 Example 6 -11.89 16.00 2.68 3.63 Comparative Example 1 -19.07 13.25 3.00 4.18

[0109] It can be seen from Table 2 and Figures 6 - 13 that compared with Examples 2, 6, and Comparative Example 1, the electromagnetic wave absorption material prepared in Example 5 has better electromagnetic wave absorption properties, with a minimum reflection loss value of -37.98 dB, a matching thickness of 2.00 mm, and also has the largest effective absorption bandwidth of 4.94 GHz; at the same time, Example 2 also has good electromagnetic wave absorption properties, with the best RL value of -33.08 dB; the best minimum RL of Example 5 is significantly smaller than the RL of Examples 2, 6, and Comparative Example 1, which may be due to the fact that Example 5 has better interfacial relaxation polarization, multiple reflection, and scattering characteristics, which can effectively improve the electromagnetic wave absorption properties; in addition, it can also be seen from Table 2 that as the proportion of magnetic Fe3O4 in the composite material gradually decreases, the electromagnetic wave absorption performance shows a trend of first increasing and then decreasing.

[0110] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing an electromagnetic wave absorbing material using coal gasification fine slag, comprising the following steps: (1) Mixing coal gasification fine slag and water to obtain coal gasification fine slag slurry, and then adding flotation reagent to carry out flotation to obtain flotation concentrate and flotation tailings; (2) performing magnetic separation on the flotation tailings obtained in step (1) to obtain magnetic Fe3O4; (3) The magnetic Fe3O4, aniline and hydrochloric acid obtained in step (2) are mixed, and then an initiator is added to carry out a polymerization reaction to obtain an electromagnetic wave absorbing material.

2. The method according to claim 1, characterized in that The concentration of the coal gasification fine slag slurry in step (1) is 10 to 100 g / L.

3. The method according to claim 1, characterized in that In the step (1), the flotation reagents include a collector and a frother; the collector includes kerosene, diesel or oleic acid; the frother includes octanol, terpineol or polyethylene glycol.

4. The method according to claim 3, characterized in that The amount of the collector is 5000-15000 g / t; the amount of the foaming agent is 5000-15000 g / t.

5. The method according to claim 1, characterized in that The magnetic separation in step (2) is wet magnetic separation.

6. The method according to claim 1, characterized in that The concentration of hydrochloric acid in step (3) is 0.05-0.15 mol / L.

7. The method according to claim 1, characterized in that In the step (3), the ratio of the mass of magnetic Fe3O4, the volume of aniline and the volume of hydrochloric acid is (40-55) mg: (100-300) μL: (80-120) mL.

8. The method according to claim 1, characterized in that In the step (3), the initiator is an ammonium persulfate solution; the concentration of the ammonium persulfate solution is 0.01-0.05 g / mL; the volume ratio of the aniline to the initiator is (100-300) μL:20 mL.

9. The method according to claim 1, characterized in that: The polymerization reaction in step (3) is carried out in an ice-water bath; the polymerization reaction time is 2 to 6 hours.

10. The electromagnetic wave absorbing material prepared by the method according to any one of claims 1 to 9.

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