Preparation method of rare earth oxide fly ash ceramsite with high load softening temperature

Abstract

The application provides a preparation method of rare earth oxide fly ash ceramsite with high load softening temperature, and comprises the following steps: step 1, fly ash pretreatment: fly ash is obtained after oscillation, high-temperature calcination, grinding and sieving; step 2, preparation of ceramsite: after ball milling and spray drying, the rare earth oxide is blended with the fly ash powder to obtain a mixed powder; step 3, balling process: the mixed powder is placed in a granulator, a binder is uniformly added into the mixed powder, and then the prepared ceramsite is aged and calcined to obtain the rare earth oxide fly ash ceramsite. The preparation method of the rare earth oxide fly ash ceramsite with high load softening temperature has the advantages that the fly ash ceramsite prepared by adding rare earth oxide has a higher load softening temperature, and the load softening temperature of the fly ash ceramsite without adding rare earth oxide is increased by more than 10%.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of ceramsite, and particularly relates to a preparation method of rare earth oxide fly ash ceramsite with high load softening temperature. BACKGROUND

[0002] Fly ash is the main waste of thermal power plants, and the average fly ash output of coal in China is 26-30 kg / t. The fly ash output of each 10,000 kilowatt power generation is about 0.9-1.0 million tons. The fly ash has a large output, occupies a large area, and forms dust, pollutes groundwater, and causes very serious environmental problems. Rare earth oxides have a wide range of applications, such as polishing powder, catalyst, hydrogen storage material, glass ceramic, PVC additive, and rare earth alloy.

[0003] A Chinese patent for invention with the publication number CN108383540A (application number 201810196846.5) discloses a method for loading rare earth oxides on the surface pores of fly ash ceramics by alkali washing, impregnation, and high-temperature calcination, so as to remove Cr 6+ from sewage. A Chinese patent application for invention with the publication number CN115504803A (application number 202211119278.1) discloses fly ash-based cordierite honeycomb ceramics and a preparation method thereof, which are prepared from fly ash and other inorganic ingredient powders, and added with a binder, a plasticizer, a dispersant, and water. Rare earth fluoride additives are added, so that the ceramics have excellent thermal and mechanical properties.

[0004] At present, there are few ceramsite products that can be applied in high-temperature environments, and there are few studies on improving the porosity of fly ash ceramsite by using rare earth oxides. Therefore, it is quite necessary to develop a ceramsite product with excellent comprehensive performance by using rare earth oxide fly ash ceramsite in response to the concept of waste-free industry and environmentally friendly city. SUMMARY

[0005] Therefore, the present application aims to overcome the defects in the prior art and provides a preparation method of rare earth oxide fly ash ceramsite with high load softening temperature.

[0006] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0007] The preparation method of rare earth oxide fly ash ceramsite with high load softening temperature comprises the following steps:

[0008] Step 1 is the pretreatment of fly ash: after the fly ash is subjected to oscillation, high-temperature calcination, grinding, and sieving, the fly ash powder is obtained;

[0009] Step 2 is the preparation of ceramsite: after the rare earth oxide is subjected to ball milling and spray drying, the mixed powder is obtained by blending the fly ash powder and the rare earth oxide.

[0010] Step 3 is the pelletizing process: the mixed powder is placed in a granulator, the binder is evenly added to the mixed powder, and then the resulting ceramsite is aged and calcined to obtain the rare earth oxide fly ash ceramsite.

[0011] Furthermore, the rare earth oxide in step 2 is at least one of lanthanum oxide, cerium oxide, samarium oxide, yttrium oxide, lanthanum cerium oxide, or lanthanum samarium oxide; the purity of the rare earth oxide in step 2 is REO≥98%; and the solid content of the rare earth oxide in step 2 is 25-80%.

[0012] Furthermore, in step 2, the ball milling process has a linear velocity of 1-13 m / s, a temperature of 15-40℃, and the resulting slurry has a particle size of 500 nm ≤ D. 90 ≤1000nm; the feed rate in step 2 of the spray drying step is 0.1-60L / min, the temperature is 210-280℃, and the particle size of the spray-dried powder is 1μm≤D 90 ≤5μm.

[0013] Furthermore, in step 2, the mass ratio of the rare earth oxide powder after spray drying to the fly ash powder is 1-12:88-99.

[0014] Furthermore, the binder in step 3 is at least one of water, water glass, aluminum dihydrogen phosphate, silica sol, aluminum sol, or zirconium sol; the mass ratio of the binder in step 3 to the mixed powder is 15-28:72-85.

[0015] Furthermore, in step 3, the tilt angle of the granulator is 30°-50° and the rotation speed is 10-60 rpm; the rate of the dropping step in step 3 is 0.0001-10 L / s; and the diameter of the ceramsite in step 3 is 1.5-15 mm.

[0016] Furthermore, the aging step in step 3 is carried out at a temperature of 18-30℃, a humidity of 35-65%, and a time of 8-24 hours.

[0017] Furthermore, the parameters for the calcination step in step 3 are as follows: the temperature is increased from room temperature to 200℃ at a rate of 5-30℃ / min, held at 200℃ for 15-300min, the temperature is increased from 200℃ to 1100-1350℃ at a rate of 3-10℃ / min, held for 1-150min, and then cooled to room temperature.

[0018] Furthermore, the grading in the oscillation step of step 1 is at 17-28K, and the cenospheres larger than 300μm are sieved out; the temperature of the high-temperature calcination step in step 1 is 750-900℃, and the time is 1-5h; the sieve residue rate after passing through a 1200-mesh sieve in the grinding step of step 1 is ≤5%.

[0019] Furthermore, the fly ash in step 1 is composed of the following components by mass percentage: 10-45% aluminum oxide, 25-55% silicon oxide, ≤15% calcium oxide, ≤5% magnesium oxide, ≤7% iron oxide, and ≤5% potassium and sodium oxide.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] The method for preparing high load softening temperature rare earth oxide fly ash ceramsite according to the present invention adds rare earth oxides. The fly ash ceramsite prepared by adding rare earth oxides has a higher load softening temperature, which is more than 10% higher than that of ceramsite without rare earth oxides. Rare earth oxides react with silicon and aluminum components in fly ash at high temperature to form rare earth silicate and rare earth aluminate. The low melting point liquid phase in the reaction process provides a more sufficient ionic thermal motion environment for the aluminum and silicon phases, which promotes the formation of kyanite, cristobalite and mullite phases of the aluminum and silicon phases at lower temperatures, thus achieving a higher load softening temperature.

[0022] The process of forming expanded ceramsite at a lower temperature reduces the firing temperature of fly ash ceramsite by more than 10%. The low-melting-point liquid phase during the high-temperature reaction of rare earth oxides with fly ash has a certain viscosity and preferentially coats the surface of the ceramsite. Through plastic deformation, it locks in the gas generated by the internal gas-forming components, forming numerous sealed pores. Therefore, the introduction of rare earth oxides can lower the firing temperature of the expanded ceramsite. Detailed Implementation

[0023] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0024] The present invention will be described in detail below with reference to the embodiments.

[0025] Example 1

[0026] A method for preparing rare earth oxide fly ash ceramsite with high load softening temperature includes the following steps:

[0027] (1) Take fly ash and classify it by vibration at 17K to remove the cenospheres larger than 300 microns. The remaining sieved fly ash is calcined at 800℃ for 5 hours and then discharged and air-cooled to 25℃. It is then ground by a high-energy air jet mill. After grinding, 1940g of material passing through a 1200-mesh sieve is taken. The composition of fly ash is 26% alumina, 45% silicon dioxide, 11% calcium oxide, 3% magnesium oxide, 6.05% iron oxide, and 1.25% potassium and sodium.

[0028] (2) Lanthanum and cerium oxide (REO = 99.56%) were prepared to a solid content of 50% and then fed into a ball mill for high-energy grinding. The linear velocity was 8 m / s, the discharge temperature was 25℃, and the mixture was ground to D. 90 Spray drying was performed at a wavelength of 500 nm, with a feed rate of 2 L / min and a thermal spray temperature of 270 °C. After drying, D... 90 60g of spray-dried lanthanum cerium oxide was taken as micro powder with a particle size of 2μm and mixed thoroughly with fly ash in a three-dimensional powder mixer for 1h to obtain mixed powder.

[0029] (3) The mixed powder is loaded into the granulator, the disc is tilted at 35°, the rotation speed is set to 20 rpm, and 200 g of neutral water is dripped evenly. When the diameter of the ceramsite is about 15 mm, it is discharged. It is aged at 25°C and 45% humidity for 14 hours. After aging, the ceramsite is loaded into the muffle furnace and heated to 200°C at 10°C / min. After holding at 200°C for 30 minutes, the temperature is increased to 1250°C at 5°C / min and held for 20 minutes to obtain lanthanum oxide cerium modified fly ash expanded ceramsite.

[0030] Example 2

[0031] A method for preparing rare earth oxide fly ash ceramsite with high load softening temperature includes the following steps:

[0032] (1) Take fly ash and classify it by vibration at 17K to remove the cenospheres larger than 300 microns. The remaining sieved fly ash is calcined at 800℃ for 5 hours and then discharged and air-cooled to 25℃. It is then ground by a high-energy air jet mill. After grinding, 1900g of material passing through a 1200 mesh sieve is taken. The fly ash composition is 26% alumina, 45% silicon oxide, 11% calcium oxide, 3% magnesium oxide, 6.05% iron oxide, and 2.25% potassium and sodium.

[0033] (2) Lanthanum oxide (99.5%) and samarium oxide (99.5%) were separately fed into a ball mill for high-energy grinding at a linear velocity of 8 m / s and a discharge temperature of 25°C until D was achieved. 90 Spray drying was performed at a wavelength of 500 nm, with a feed rate of 2 L / min and a thermal spray temperature of 270 °C. After drying, D... 90 The micro powder with a particle size of 2μm was obtained by thoroughly mixing 70g of lanthanum oxide, 30g of samarium oxide and fly ash in a three-dimensional mixer for 1 hour to obtain a mixed powder.

[0034] (3) The mixed powder is loaded into the granulator, the disc is tilted at 35°, the rotation speed is set to 20 rpm, and 200 g of water glass (10%) is evenly dripped in. When the diameter of the ceramsite is about 15 mm, it is discharged. It is aged at 25°C and 45% humidity for 14 hours. After aging, the ceramsite is loaded into the muffle furnace and heated to 200°C at 10°C / min. After holding at 200°C for 30 minutes, the temperature is increased to 1190°C at 5°C / min and held for 20 minutes to obtain lanthanum oxide and samarium oxide modified fly ash expanded ceramsite.

[0035] Example 3

[0036] A method for preparing rare earth oxide fly ash ceramsite with high load softening temperature includes the following steps:

[0037] (1) Take fly ash and classify it by vibration at 17K to remove the cenospheres larger than 300 microns. The remaining sieved fly ash is calcined at 800℃ for 5 hours and then discharged and air-cooled to 25℃. It is then ground by a high-energy air jet mill. After grinding, 1900g of material passing through a 1200 mesh sieve is taken. The fly ash composition is 26% alumina, 45% silicon oxide, 11% calcium oxide, 3% magnesium oxide, 6.05% iron oxide, and 2.25% potassium and sodium.

[0038] (2) Lanthanum oxide (3N) and yttrium oxide (3N) were separately fed into a ball mill for high-energy grinding at a linear velocity of 8 m / s and a discharge temperature of 25°C until D was obtained. 90 Spray drying was performed at a wavelength of 500 nm, with a feed rate of 2 L / min and a thermal spray temperature of 270 °C. After drying, D... 90 The micro powder with a particle size of 2μm was obtained by thoroughly mixing 110g of lanthanum oxide, 30g of yttrium oxide and fly ash in a three-dimensional mixer for 1 hour to obtain a mixed powder.

[0039] (3) The mixed powder is loaded into the granulator, the disc is tilted at 35°, the rotation speed is set to 20 rpm, and 200 g of aluminum dihydrogen phosphate solution (5%) is evenly dripped in. When the diameter of the ceramsite is about 15 mm, it is discharged. It is aged at 25°C and 45% humidity for 14 h. After aging, the ceramsite is loaded into a muffle furnace and heated to 200°C at 10°C / min. After holding at 200°C for 30 min, the temperature is increased to 1170°C at 5°C / min and held for 20 min to obtain lanthanum oxide and yttrium oxide modified fly ash expanded ceramsite.

[0040] Comparative Example 1

[0041] A method for preparing fly ash ceramsite includes the following steps:

[0042] (1) Take fly ash and classify it by vibration at 17K to remove the cenospheres larger than 300 microns. The remaining sieved fly ash is calcined at 800℃ for 5 hours and then discharged and air-cooled to 25℃. It is then ground by a high-energy air jet mill. After grinding, 1940g of material passing through a 1200-mesh sieve is taken. The composition of fly ash is 26% alumina, 45% silicon dioxide, 11% calcium oxide, 3% magnesium oxide, 6.05% iron oxide, and 1.25% potassium and sodium.

[0043] (2) The mixed powder is loaded into the granulator, the disc is tilted at 35°, the rotation speed is set to 20 rpm, and 200 g of neutral water is dripped evenly. When the diameter of the ceramsite is about 15 mm, it is discharged. It is aged at 25°C and 45% humidity for 14 hours. After aging, the ceramsite is loaded into the muffle furnace and heated to 200°C at 10°C / min. After holding at 200°C for 30 minutes, the temperature is increased to 1250°C at 5°C / min and held for 20 minutes to obtain fly ash expanded ceramsite.

[0044] Comparative Example 2

[0045] A method for preparing rare earth oxide fly ash ceramsite with high load softening temperature includes the following steps:

[0046] (1) Take 1940g of fly ash. The fly ash composition is 22% aluminum oxide, 53% silicon oxide, 9% calcium oxide, 2.3% magnesium oxide, 4.95% iron oxide, and 3.35% potassium and sodium.

[0047] (2) Lanthanum and cerium oxide (REO = 99.56%) were prepared to a solid content of 50% and then fed into a ball mill for high-energy grinding. The linear velocity was 8 m / s, the discharge temperature was 25℃, and the mixture was ground to D. 90 Spray drying was performed at a wavelength of 500 nm, with a feed rate of 2 L / min and a thermal spray temperature of 270 °C. After drying, D... 90 60g of spray-dried lanthanum cerium oxide was taken as micro powder with a particle size of 2μm and mixed thoroughly with fly ash in a three-dimensional powder mixer for 1h to obtain mixed powder.

[0048] (3) The mixed powder was loaded into the granulator, the disc was tilted at 35°, the rotation speed was set to 20 rpm, and 200 g of neutral water was evenly dripped in. When the diameter of the ceramsite d = 15 mm, it was discharged. It was aged at 25°C and 45% humidity for 14 hours. After aging, the ceramsite was loaded into a muffle furnace and heated to 200°C at 10°C / min. After holding at 200°C for 30 minutes, the temperature was increased to 1250°C at 5°C / min and held for 20 minutes. The product contained low melting point glass microspheres. After the ceramsite was calcined at 1250°C, it melted and liquefied and could not maintain its spherical shape.

[0049] Comparative Example 3

[0050] A method for preparing rare earth oxide fly ash ceramsite with high load softening temperature includes the following steps:

[0051] (1) Fly ash was subjected to vibration and classification at 17K to remove cenospheres larger than 300 microns. The remaining sieved fly ash was calcined at 800℃ for 5 hours and then discharged and air-cooled to 25℃. 1940g of the material was then taken. The composition of the fly ash was 26% alumina, 45% silicon oxide, 11% calcium oxide, 3% magnesium oxide, 6.05% iron oxide, and 1.25% potassium and sodium.

[0052] (2) Lanthanum and cerium oxide (REO = 99.56%) were prepared to a solid content of 50% and then fed into a ball mill for high-energy grinding. The linear velocity was 8 m / s, the discharge temperature was 25℃, and the mixture was ground to D. 90 Spray drying was performed at a wavelength of 500 nm, with a feed rate of 2 L / min and a thermal spray temperature of 270 °C. After drying, D... 90 60g of spray-dried lanthanum cerium oxide was taken as micro powder with a particle size of 2μm and mixed thoroughly with fly ash in a three-dimensional powder mixer for 1h to obtain mixed powder.

[0053] (3) The mixed powder is loaded into the granulator, the disc is tilted at 35°, the rotation speed is set to 20 rpm, and 200 g of neutral water is dripped evenly. When the diameter of the ceramsite is about 15 mm, it is discharged. It is aged at 25°C and 45% humidity for 14 hours. After aging, the ceramsite is loaded into the muffle furnace and heated to 200°C at 10°C / min. After holding at 200°C for 30 min, the temperature is increased to 1250°C at 5°C / min and held for 20 min. Lanthanum oxide cerium modified fly ash expanded ceramsite can be obtained. The spectral composition of the lanthanum oxide cerium fly ash mixed powder material is not uniform, the expansion pores are unevenly distributed and the pores are easily distributed on the surface of the ceramsite, and no pores are generated in the core layer of the ceramsite.

[0054] The performance of the ceramsite products of each embodiment and each comparative example was tested, and the results are shown in Table 1.

[0055] Table 1 Performance Data Table

[0056]

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing rare earth oxide fly ash ceramsite with high load softening temperature, characterized in that: Includes the following steps: Step 1 is the pretreatment of fly ash: fly ash is obtained by shaking, high-temperature roasting, grinding and sieving. Step 2 is the preparation of ceramsite: rare earth oxides are ball-milled, spray-dried, and then blended with the fly ash powder to obtain a mixed powder; Step 3 is the pelletizing process: the mixed powder is placed in a granulator, the binder is evenly added to the mixed powder, and then the resulting ceramsite is aged and calcined to obtain the rare earth oxide fly ash ceramsite. The rare earth oxide in step 2 is at least one of lanthanum oxide, cerium oxide, samarium oxide, yttrium oxide, lanthanum cerium oxide, or lanthanum samarium oxide; the purity of the rare earth oxide in step 2 is REO≥98%; the solid content of the rare earth oxide in step 2 is 25-80%. In step 2, the mass ratio of the rare earth oxide powder after spray drying to the fly ash powder is 1-12:88-99.

2. The method for preparing rare earth oxide fly ash ceramsite with high load softening temperature according to claim 1, characterized in that: The ball milling step in step 2 has a linear velocity of 1-13 m / s, a temperature of 15-40℃, and a particle size of 500 nm ≤ D after grinding. 90 ≤1000nm; the feed rate in step 2 of the spray drying step is 0.1-60L / min, the temperature is 210-280℃, and the particle size of the spray-dried powder is 1μm≤D 90 ≤5μm.

3. The method for preparing rare earth oxide fly ash ceramsite with high load softening temperature according to claim 1, characterized in that: The binder in step 3 is at least one of water, water glass, aluminum dihydrogen phosphate, silica sol, aluminum sol, or zirconium sol; the mass ratio of the binder to the mixed powder in step 3 is 15-28:72-85.

4. The method for preparing rare earth oxide fly ash ceramsite with high load softening temperature according to claim 1, characterized in that: The tilt angle of the granulator in step 3 is 30°-50° and the rotation speed is 10-60 rpm; the dripping rate in step 3 is 0.0001-10 L / s; and the diameter of the ceramsite in step 3 is 1.5-15 mm.

5. The method for preparing rare earth oxide fly ash ceramsite with high load softening temperature according to claim 1, characterized in that: The aging step in step 3 is carried out at a temperature of 18-30℃, a humidity of 35-65%, and a time of 8-24 hours.

6. The method for preparing rare earth oxide fly ash ceramsite with high load softening temperature according to claim 1, characterized in that: The parameters for the calcination step in step 3 are as follows: the temperature is increased from room temperature to 200℃ at a rate of 5-30℃ / min, held at 200℃ for 15-300min, and then increased from 200℃ to 1100-1350℃ at a rate of 3-10℃ / min, held for 1-150min, and then cooled to room temperature.

7. The method for preparing rare earth oxide fly ash ceramsite with high load softening temperature according to claim 1, characterized in that: The grading in the oscillation step of step 1 is at 17-28K, and the sieves out particles larger than 300μm; the temperature of the high-temperature calcination step in step 1 is 750-900℃, and the time is 1-5h; the sieve residue rate after passing through a 1200-mesh sieve in the grinding step of step 1 is ≤5%.

8. The method for preparing rare earth oxide fly ash ceramsite with high load softening temperature according to claim 1, characterized in that: The fly ash in step 1 is composed of the following components by mass percentage: 10-45% aluminum oxide, 25-55% silicon oxide, ≤15% calcium oxide, ≤5% magnesium oxide, ≤7% iron oxide, and ≤5% potassium and sodium oxide.

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