Preparation process of low porosity white corundum

Abstract

This invention discloses a preparation process for low-porosity white fused alumina, comprising the steps of: (1) mixing white fused alumina particles with Al... 3+ Source, Zr 4+ After the source treatment solution is mixed and allowed to stand, the Al 3+ Source, Zr 4+ An excess of one of the sources. After completion, the white fused alumina particles are separated and placed in a mixed atmosphere of ammonia and water vapor for alkaline evaporation. Then, the obtained white fused alumina particles are calcined to obtain pretreated white fused alumina. (2) The pretreated white fused alumina is placed in a Fe solution containing the same molar ratio. 2+ Fe 3+ After mixing thoroughly in the treatment solution, the pretreated white fused alumina is allowed to stand. Once completed, the pretreated white fused alumina is separated and subjected to alkaline evaporation in a mixed atmosphere of ammonia and water vapor. The resulting pretreated white fused alumina is then calcined to obtain low-porosity white fused alumina. The above process of the present invention is suitable for post-treatment of finished white fused alumina with excessively high porosity, effectively reducing the porosity of this type of white fused alumina and improving its service life.

Description

Technical Field

[0001] This invention relates to the field of white fused alumina preparation technology, and specifically to a preparation process for low-porosity white fused alumina. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] White fused alumina is made from alumina or bauxite as raw materials, smelted at high temperatures in a reducing atmosphere, and then processed through crushing, shaping, magnetic separation to remove iron, and sieving. Its alumina content is over 99%, with small amounts of iron oxide and silicon oxide. Alumina is a major component of the Earth's crust, possessing abundant resources and relatively low cost. White fused alumina is a high-hardness ceramic material with excellent wear resistance, corrosion resistance, and high-temperature resistance. Its angular grain shape makes it suitable for manufacturing ceramics, resin-bonded abrasives, and for grinding, polishing, sandblasting, and precision casting. It is also an indispensable raw material for producing high-grade refractory materials. However, due to the characteristics of the raw material, white fused alumina has a certain degree of porosity, including large pores existing individually or in clusters of multiple pores. The apparent porosity typically reaches 6-10%. This high porosity results in a brittle and hard nature, reducing its impact resistance and making it more susceptible to damage during use as an abrasive, thus affecting its service life. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a process for preparing low-porosity white fused alumina. This process is suitable for post-processing finished white fused alumina with excessively high porosity, effectively reducing its porosity and improving its service life. To achieve the above objectives, this invention discloses the following technical solution.

[0005] A process for preparing low-porosity white fused alumina includes the following steps:

[0006] (1) Mix white corundum particles with Al 3+ Source, Zr 4+ After the source treatment solution is mixed and allowed to stand, the Al 3+ Source, Zr 4+ An excess of a certain amount of the source. After settling, the white fused alumina particles are separated and placed in a mixed atmosphere of ammonia and water vapor for alkaline steaming. The resulting white fused alumina particles are then calcined to obtain pretreated white fused alumina for later use.

[0007] (2) The pretreated white fused alumina was placed in a Fe solution containing the same molar ratio. 2+ Fe 3+After being mixed in the treatment solution and allowed to stand, the pretreated white fused alumina was separated and placed in a mixed atmosphere of ammonia and water vapor for alkaline evaporation. Then, the pretreated white fused alumina was calcined in a protective atmosphere to obtain low-porosity white fused alumina.

[0008] Further, in step (1), the ratio of the white fused alumina particles to the treatment solution is 1g:20-40ml. Any other suitable ratio can also be used, as long as the white fused alumina particles are fully immersed in the treatment solution.

[0009] Further, in step (1), the Zr 4+ When the source is excessive, the Zr in the treatment solution 4+ The source is in a saturated state, and the Zr 4+ The mass fraction of the source is Al 3+ The amount of zirconium oxide is 1.2 to 1.5 times the mass fraction of the source, so that the pretreated white corundum obtained after calcination contains residual zirconium oxide.

[0010] Further, in step (1), the Al 3+ When the source is excessive, the Al in the treatment solution 3+ The source is saturated, and the Al 3+ The mass fraction of the source is Zr 4+ The amount of zirconium oxide is 1.25 to 1.45 times the source mass fraction, so that the pretreated white corundum obtained after calcination contains residual zirconium oxide.

[0011] Further, in step (1), the Al 3+ The source includes at least one of aluminum chloride, aluminum sulfate, aluminum nitrate, etc.

[0012] Further, in step (1), the Zr 4+ The source includes at least one of zirconium chloride, zirconium sulfate, zirconium nitrate, etc.

[0013] Furthermore, in step (1), the settling time is 30-50 minutes, allowing the white corundum to fully absorb the Al in the treatment solution using its pores. 3+ and Zr 4+ .

[0014] Further, in step (1), the white fused alumina particles are placed above ammonia water, and then heated to form a mixed atmosphere of ammonia gas and water vapor, thereby subjecting the white fused alumina particles to alkaline evaporation. Optionally, the mass concentration of the ammonia water is 15-25%. Further, the heating temperature is 70-85°C, and the alkaline evaporation treatment time is 40-60 minutes.

[0015] Furthermore, in step (1), the calcination treatment is carried out at a temperature of 1500–1600°C for 1.5–2 hours.

[0016] Further, in step (2), the ratio of the pretreated white fused alumina to the treatment solution is 1g:20-35ml. Other suitable ratios can also be used, as long as the pretreated white fused alumina is fully immersed in the treatment solution.

[0017] Further, in step (2), the Fe in the mixture 2+ Fe 3+ The molar concentration is between 1 and 2 mol / L. Optionally, the Fe... 2+ It can be composed of at least one of ferrous chloride, ferrous sulfate, and ferrous nitrate. The Fe... 3+ It can be made from at least one of ferric chloride, ferric sulfate, ferric nitrate, etc.

[0018] Furthermore, in step (2), the settling time is 30-40 minutes, allowing the pretreated white corundum to further absorb Fe from the treatment solution using its pores. 2+ Fe 3+ .

[0019] Further, in step (2), the pretreated white fused alumina is placed above ammonia water and then heated to form a mixed atmosphere of ammonia gas and water vapor, thereby subjecting the pretreated white fused alumina to alkaline evaporation. Optionally, the mass concentration of the ammonia water is 15-25%. Further, the heating temperature is 70-85°C, and the alkaline evaporation treatment time is 30-45 minutes.

[0020] Further, in step (2), the calcination treatment is carried out at a temperature of 850–950°C for 1–1.5 hours. Optionally, the protective atmosphere includes any one of nitrogen, argon, etc.

[0021] Compared with the prior art, the present invention achieves at least the following beneficial technical effects: As mentioned above, white fused alumina has a certain degree of porosity after preparation due to various reasons, especially when the process control is improper, the porosity of the white fused alumina is even higher, affecting its service life. To address the above problems, the present invention first places the white fused alumina in an Al-containing environment... 3+ Source, Zr 4+ The source treatment solution utilizes the pores of white fused alumina to absorb Al. 3+ and Zr 4+ Then, this invention utilizes the volatile nature of ammonia water to perform alkaline steam treatment on the white fused alumina. This facilitates the entry of ammonia gas and water vapor generated during the process into the pores of the white fused alumina, thereby converting the Al... 3+ and Zr 4+The aluminum hydroxide and zirconium hydroxide are converted into aluminum hydroxide and zirconium hydroxide to fill the pores. Simultaneously, this method minimizes the introduction of aluminum and zirconium impurities into the non-porous parts of the white fused alumina, reducing the impact on the overall purity of the white fused alumina. After further calcination, the aluminum hydroxide and zirconium hydroxide in the pores of the white fused alumina first decompose into oxides, and then further react to form an aluminum zirconate ceramic phase (Al2O3 + ZrO2 → Al2O9Zr3) filling the pores of the white fused alumina. Compared with white fused alumina, whose main component is aluminum oxide, aluminum zirconate ceramic has higher hardness and stronger wear resistance, thus effectively embedding a high-hardness reinforcing phase into the white fused alumina matrix. When the white fused alumina wears down to the reinforcing phase during use, the reinforcing phase must be worn down first before the white fused alumina matrix can be further worn down. Because the reinforcing phase has higher hardness and is more wear-resistant, it can effectively delay the wear of the white fused alumina matrix, improving its impact resistance and service life. Furthermore, since aluminum hydroxide and zirconium hydroxide decompose and release moisture during the above-mentioned calcination process, new pores will form in the white fused alumina. Therefore, the present invention places the pretreated white fused alumina obtained through the above treatment in Fe... 2+ Fe 3+ In the treatment solution, Fe is further absorbed using the new pores. 2+ and Fe 3+ Then, ammonia gas and water vapor formed by ammonia water are used again to enter the pores to collect Fe. 2+ and Fe 3+ It is converted into hydroxide. After calcination, the hydroxide decomposes into FeO and Fe2O3 under a protective atmosphere, which further react to form Fe3O4, filling the pores (FeO + Fe2O3 → Fe3O4). Due to the Al... 3+ Source or Zr 4+ Excessive Al₂O₃ or ZrO₂ content results in an excess of Al₂O₃ or ZrO₂ within the pores of white fused alumina. This ZrO₂ then combines with Fe₃O₄ to form Fe₃O₄ / ZrO₂ or Fe₃O₄ / Al₂O₃ composite particles. On one hand, the conversion of Fe₂O₃ to Fe₃O₄ causes volume expansion, which better fills the pores and further reduces the porosity of the white fused alumina. On the other hand, the composite particles formed by Al₂O₃ or ZrO₂ overcome the insufficient hardness and wear resistance of Fe₃O₄, thereby improving the service life of the white fused alumina matrix. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 The image shows the effect of the low-porosity white corundum prepared in Example 1 of the present invention. Detailed Implementation

[0024] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer. Furthermore, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as those skilled in the art.

[0025] The reagents and raw materials used in this invention can all be purchased through conventional channels. Unless otherwise specified, the reagents and raw materials used in this invention shall be used in accordance with conventional methods in the art or according to the product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the methods of this invention. The preferred embodiments and materials described in this invention are for illustrative purposes only. The preparation process of low-porosity white fused alumina of this invention will now be further illustrated with reference to the accompanying drawings and specific embodiments.

[0026] Example 1

[0027] A process for preparing low-porosity white fused alumina includes the following steps:

[0028] (1) Aluminum sulfate was added to a saturated zirconium sulfate solution at room temperature and stirred until homogeneous to form a treatment solution, wherein the mass fraction of zirconium sulfate was 1.5 times that of aluminum sulfate. Then, white fused alumina particles were added to the treatment solution at a ratio of 1 g: 30 ml, stirred until homogeneous, and allowed to stand for 40 min. The white fused alumina particles were then filtered out and placed in a reaction vessel containing 20% ​​ammonia solution, with the particles positioned on a mesh plate above the ammonia solution. The mixture was then heated in a water bath to 80°C and held for 50 min for alkaline evaporation treatment. After completion, the white fused alumina particles were removed and transferred to a heating furnace and heated at 1550°C for 2 hours. After completion, the mixture was cooled to room temperature to obtain pretreated white fused alumina for later use.

[0029] (2) The pretreated white corundum was placed in a treatment solution of ferrous sulfate and ferric sulfate at a ratio of 1g:30ml (wherein Fe... 2+ Fe 3+ The pretreated white fused alumina was stirred evenly in a solution of 1.5 mol / L and allowed to stand for 35 minutes. Then, the pretreated white fused alumina was filtered out and placed in a reactor containing 20% ​​ammonia solution, with the pretreated white fused alumina positioned on a mesh plate above the ammonia solution. The solution was then heated in a water bath to 80°C and held for 50 minutes for alkaline evaporation treatment. After completion, the pretreated white fused alumina was removed and transferred to a heating furnace under a nitrogen protective atmosphere and heated at 900°C for 1.5 hours. After cooling to room temperature, low-porosity white fused alumina was obtained. Figure 1As shown.

[0030] The bulk density, apparent porosity, and wear resistance of the low-porosity white fused alumina prepared in this embodiment were tested. The results showed that the bulk density was 3.82 g / cm³. 3 The apparent porosity is 2.27%, and the wear resistance is 1.46g. A lower wear resistance value indicates less white fused alumina wears off during the test time, signifying better wear resistance. It can be seen that the low-porosity white fused alumina treated in this embodiment exhibits better performance (bulk density = 3.62g / cm³) compared to the initial white fused alumina. 3 The apparent porosity (7.48%) and wear resistance (1.97g) were significantly improved.

[0031] Example 2

[0032] A process for preparing low-porosity white fused alumina includes the following steps:

[0033] (1) Aluminum sulfate was added to a saturated zirconium sulfate solution at room temperature and stirred until homogeneous to form a treatment solution, wherein the mass fraction of zirconium sulfate was 1.2 times that of aluminum sulfate. Then, white fused alumina particles were added to the treatment solution at a ratio of 1g:20ml, stirred until homogeneous, and allowed to stand for 30 minutes. The white fused alumina particles were then filtered out and placed in a reactor containing 15% ammonia solution, with the particles positioned on a mesh plate above the ammonia solution. The reactor was then heated in a water bath to 70°C and held for 60 minutes for alkaline evaporation treatment. After completion, the white fused alumina particles were removed and transferred to a furnace and heated at 1500°C for 2 hours. After completion, the mixture was cooled to room temperature to obtain pretreated white fused alumina for later use.

[0034] (2) The pretreated white corundum was placed in a treatment solution of ferrous sulfate and ferric sulfate at a ratio of 1g:20ml (wherein Fe... 2+ Fe 3+ The pretreated white fused alumina was stirred thoroughly in a solution of 1 mol / L ammonia solution and allowed to stand for 30 minutes. The pretreated white fused alumina was then filtered out and placed in a reactor containing 15% ammonia solution, with the pretreated white fused alumina positioned on a mesh plate above the ammonia solution. The solution was then heated in a water bath to 85°C and held for 30 minutes for alkaline evaporation treatment. After completion, the pretreated white fused alumina was removed and transferred to a heating furnace under a nitrogen protective atmosphere and heated at 850°C for 1.5 hours. After cooling to room temperature, low-porosity white fused alumina was obtained.

[0035] The bulk density, apparent porosity, and wear resistance of the low-porosity white fused alumina prepared in this embodiment were tested. The results showed that the bulk density was 3.87 g / cm³. 3The apparent porosity is 2.14%, and the wear resistance is 1.38g. It can be seen that the low-porosity white fused alumina treated in this embodiment exhibits significantly improved properties compared to the initial white fused alumina.

[0036] Example 3

[0037] A process for preparing low-porosity white fused alumina includes the following steps:

[0038] (1) Zirconium chloride was added to a saturated aluminum chloride solution at room temperature and stirred until homogeneous to form a treatment solution, with the mass fraction of aluminum chloride being 1.25 times that of zirconium chloride. White fused alumina particles were then added to the treatment solution at a ratio of 1 g:35 ml, stirred until homogeneous, and allowed to stand for 35 min. The white fused alumina particles were then filtered out and placed in a reactor containing 25% ammonia solution, with the particles positioned on a mesh plate above the ammonia solution. The reactor was then heated in a water bath to 75°C and held for 50 min for alkaline evaporation treatment. After completion, the white fused alumina particles were removed and transferred to a furnace and heated at 1570°C for 1.5 hours. After completion, the mixture was cooled to room temperature to obtain pretreated white fused alumina for later use.

[0039] (2) The pretreated white corundum was placed in a treatment solution of ferrous chloride and ferric chloride at a ratio of 1g:25ml (wherein Fe... 2+ Fe 3+ The pretreated white fused alumina was stirred thoroughly in a solution of 1.5 mol / L ammonia solution and allowed to stand for 40 minutes. The pretreated white fused alumina was then filtered out and placed in a reactor containing 25% ammonia solution, with the pretreated white fused alumina positioned on a mesh plate above the ammonia solution. The solution was then heated in a water bath to 75°C and held for 40 minutes for alkaline evaporation treatment. After completion, the pretreated white fused alumina was removed and transferred to a heating furnace under a nitrogen protective atmosphere and heated at 880°C for 1 hour. After cooling to room temperature, low-porosity white fused alumina was obtained.

[0040] The bulk density, apparent porosity, and wear resistance of the low-porosity white fused alumina prepared in this embodiment were tested. The results showed that the bulk density was 3.96 g / cm³. 3 The apparent porosity is 1.88%, and the wear resistance is 1.25g. It can be seen that the low-porosity white fused alumina treated in this embodiment exhibits significantly improved properties compared to the initial white fused alumina.

[0041] Example 4

[0042] A process for preparing low-porosity white fused alumina includes the following steps:

[0043] (1) Zirconium nitrate was added to a saturated aluminum nitrate solution at room temperature and stirred until homogeneous to form a treatment solution, wherein the mass fraction of aluminum nitrate was 1.45 times that of zirconium nitrate. Then, white fused alumina particles were added to the treatment solution at a ratio of 1 g: 40 ml, stirred until homogeneous, and allowed to stand for 50 min. The white fused alumina particles were then filtered out and placed in a reactor containing 20% ​​ammonia solution, with the particles positioned on a mesh plate above the ammonia solution. The reactor was then heated in a water bath to 85°C and held for 40 min for alkaline evaporation treatment. After completion, the white fused alumina particles were removed and transferred to a furnace and heated at 1600°C for 1.5 hours. After completion, the mixture was cooled to room temperature to obtain pretreated white fused alumina for later use.

[0044] (2) The pretreated white corundum was placed in a treatment solution of ferrous nitrate and ferric nitrate at a ratio of 1g:35ml (wherein Fe... 2+ Fe 3+ The pretreated white fused alumina was stirred thoroughly in a solution of 2 mol / L ammonia solution and allowed to stand for 40 minutes. The pretreated white fused alumina was then filtered out and placed in a reactor containing 20% ​​ammonia solution, with the pretreated white fused alumina positioned on a mesh plate above the ammonia solution. The solution was then heated in a water bath to 70°C and held for 45 minutes for alkaline evaporation treatment. After completion, the pretreated white fused alumina was removed and transferred to a heating furnace under a nitrogen protective atmosphere and heated at 950°C for 1 hour. After cooling to room temperature, low-porosity white fused alumina was obtained.

[0045] The bulk density, apparent porosity, and wear resistance of the low-porosity white fused alumina prepared in this embodiment were tested. The results showed that the bulk density was 3.91 g / cm³. 3 The apparent porosity is 2.03%, and the wear resistance is 1.31g. It can be seen that the low-porosity white fused alumina treated in this embodiment exhibits significantly improved properties compared to the initial white fused alumina.

[0046] Example 5

[0047] A process for preparing low-porosity white fused alumina includes the following steps: Aluminum sulfate is added to a room-temperature saturated solution of zirconium sulfate and stirred until homogeneous to form a treatment solution, wherein the mass fraction of zirconium sulfate is 1.5 times the mass fraction of aluminum sulfate. Then, white fused alumina particles are added to the treatment solution at a ratio of 1g:30ml, stirred until homogeneous, and allowed to stand for 40 minutes. The white fused alumina particles are then filtered out and placed in a reaction vessel containing 20% ​​ammonia solution, with the particles positioned on a mesh plate above the ammonia solution. The mixture is then heated in a water bath to 80°C and held for 50 minutes for alkaline evaporation treatment. After completion, the white fused alumina particles are removed and transferred to a heating furnace and heated at 1550°C for 2 hours. Finally, the mixture is cooled to room temperature to obtain low-porosity white fused alumina.

[0048] The bulk density, apparent porosity, and wear resistance of the low-porosity white fused alumina prepared in this embodiment were tested. The bulk density and apparent porosity of the low-porosity white fused alumina prepared in this embodiment were tested, and the results showed: bulk density = 3.68 g / cm³. 3 The apparent porosity was 3.51%, and the wear resistance was 1.59g. It can be seen that the improvement in various properties of the low-porosity white fused alumina treated in this embodiment compared to the initial white fused alumina is lower than that in Examples 1-4 above.

[0049] Example 6

[0050] A process for preparing low-porosity white fused alumina includes the following steps:

[0051] (1) Aluminum sulfate was added to a saturated zirconium sulfate solution at room temperature and stirred until homogeneous to form a treatment solution, wherein the mass fraction of zirconium sulfate was 1.2 times that of aluminum sulfate. Then, white fused alumina particles were added to the treatment solution at a ratio of 1g:20ml, stirred until homogeneous, and allowed to stand for 30 minutes. The white fused alumina particles were then filtered out and placed in a reactor containing 15% ammonia solution, with the particles positioned on a mesh plate above the ammonia solution. The reactor was then heated in a water bath to 70°C and held for 60 minutes for alkaline evaporation treatment. After completion, the white fused alumina particles were removed and transferred to a furnace and heated at 1500°C for 2 hours. After completion, the mixture was cooled to room temperature to obtain pretreated white fused alumina for later use.

[0052] (2) The pretreated white corundum was placed in a treatment solution of ferrous sulfate and ferric sulfate at a ratio of 1g:20ml (wherein Fe... 2+ Fe 3+ The solution (containing 1 mol / L of each component) was stirred thoroughly and allowed to stand for 30 minutes. The pretreated white fused alumina was then filtered out and transferred to a heating furnace under a nitrogen protective atmosphere, and heated at 850°C for 1.5 hours. After completion, it was cooled to room temperature to obtain low-porosity white fused alumina.

[0053] The bulk density, apparent porosity, and wear resistance of the low-porosity white fused alumina prepared in this embodiment were tested. The results showed that the bulk density was 3.71 g / cm³. 3 The apparent porosity was 3.43%, and the wear resistance was 1.64g. It can be seen that the improvement in various properties of the low-porosity white fused alumina treated in this embodiment compared to the initial white fused alumina is lower than that in Examples 1-4 above.

[0054] Example 7

[0055] A process for preparing low-porosity white fused alumina includes the following steps:

[0056] (1) Zirconium chloride was added to a saturated aluminum chloride solution at room temperature and stirred until homogeneous to form a treatment solution, with the mass fraction of aluminum chloride being 1.25 times that of zirconium chloride. White fused alumina particles were then added to the treatment solution at a ratio of 1 g:35 ml, stirred until homogeneous, and allowed to stand for 35 min. The white fused alumina particles were then filtered out and placed in a reactor containing 25% ammonia solution, with the particles positioned on a mesh plate above the ammonia solution. The reactor was then heated in a water bath to 75°C and held for 50 min for alkaline evaporation treatment. After completion, the white fused alumina particles were removed and transferred to a furnace and heated at 1570°C for 1.5 hours. After completion, the mixture was cooled to room temperature to obtain pretreated white fused alumina for later use.

[0057] (2) The pretreated white corundum was placed in a treatment solution of ferrous chloride and ferric chloride at a ratio of 1g:25ml (wherein Fe... 2+ Fe 3+ The pretreated white fused alumina was stirred thoroughly in a solution of 1.5 mol / L ammonia solution and allowed to stand for 40 minutes. Then, the pretreated white fused alumina was filtered out and placed in a reactor containing 25% ammonia solution, with the pretreated white fused alumina positioned on a mesh plate above the ammonia solution. The reactor was then heated in a water bath to 75°C and held for 40 minutes for alkaline evaporation treatment. After completion, the pretreated white fused alumina was removed, dried, and the low-porosity white fused alumina was obtained.

[0058] The bulk density, apparent porosity, and wear resistance of the low-porosity white fused alumina prepared in this embodiment were tested. The results showed that the bulk density was 3.74 g / cm³. 3 The apparent porosity was 2.92%, and the wear resistance was 1.71g. It can be seen that the improvement in various properties of the low-porosity white fused alumina treated in this embodiment compared to the initial white fused alumina is lower than that in Examples 1-4 above.

[0059] Example 8

[0060] A process for preparing low-porosity white fused alumina includes the following steps:

[0061] (1) Zirconium nitrate is added to a saturated aluminum nitrate solution at room temperature and stirred until homogeneous to form a treatment solution, wherein Al 3+ and Zr 4+The molar ratio was 2:1 to ensure complete reaction between the alumina and zirconium oxide formed during subsequent calcination. White fused alumina particles were then added to the treatment solution at a ratio of 1g:40ml, stirred thoroughly, and allowed to stand for 50 minutes. The white fused alumina particles were then filtered out and placed in a reactor containing 20% ​​ammonia solution, with the particles positioned on a mesh plate above the ammonia solution. The mixture was then heated in a water bath to 85°C and held for 40 minutes for alkaline evaporation treatment. After completion, the white fused alumina particles were removed and transferred to a furnace and heated at 1600°C for 1.5 hours. After cooling to room temperature, pretreated white fused alumina was obtained for later use.

[0062] (2) The pretreated white corundum was placed in a treatment solution of ferrous nitrate and ferric nitrate at a ratio of 1g:35ml (wherein Fe... 2+ Fe 3+ The pretreated white fused alumina was stirred thoroughly in a solution of 2 mol / L ammonia solution and allowed to stand for 40 minutes. The pretreated white fused alumina was then filtered out and placed in a reactor containing 20% ​​ammonia solution, with the pretreated white fused alumina positioned on a mesh plate above the ammonia solution. The solution was then heated in a water bath to 70°C and held for 45 minutes for alkaline evaporation treatment. After completion, the pretreated white fused alumina was removed and transferred to a heating furnace under a nitrogen protective atmosphere and heated at 950°C for 1 hour. After cooling to room temperature, low-porosity white fused alumina was obtained.

[0063] The bulk density, apparent porosity, and wear resistance of the low-porosity white fused alumina prepared in this embodiment were tested. The results showed that the bulk density was 3.85 g / cm³. 3 The apparent porosity was 2.17%, and the wear resistance was 1.61g. It can be seen that the improvement in various properties of the low-porosity white fused alumina treated in this embodiment compared to the initial white fused alumina is lower than that in Examples 1-4 above.

[0064] Example 9

[0065] A preparation process for low-porosity white fused alumina includes the following steps: White fused alumina particles are placed in a treatment solution of ferrous sulfate and ferric sulfate at a ratio of 1g:20ml (where Fe... 2+ Fe 3+ The mixture was stirred thoroughly in a solution of 1 mol / L ammonia solution and allowed to stand for 30 minutes. The white fused alumina particles were then filtered out and placed in a reactor containing 15% ammonia solution, with the particles positioned on a mesh plate above the ammonia solution. The reactor was then heated in a water bath to 85°C and held for 30 minutes for alkaline evaporation treatment. After this process, the white fused alumina particles were removed and transferred to a furnace under a nitrogen atmosphere and heated at 850°C for 1.5 hours. After cooling to room temperature, low-porosity white fused alumina was obtained.

[0066] The bulk density, apparent porosity, and wear resistance of the low-porosity white fused alumina prepared in this embodiment were tested. The results showed that the bulk density was 3.63 g / cm³. 3 The apparent porosity is 3.57%, and the wear resistance is 1.88g. It can be seen that the improvement in various properties of the low-porosity white fused alumina treated in this embodiment compared to the initial white fused alumina is lower than that in Examples 1-4 above.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for producing low porosity white corundum, characterized by, The method comprises the following steps: (1) mixing white corundum particles with a treatment liquid 1 containing Al 3+ source and Zr 4+ source, and then allowing the mixture to stand, with one of the Al 3+ source and Zr 4+ sources being in excess; separating the white corundum particles after the standing is completed, and subjecting the white corundum particles to alkali steaming in a mixed atmosphere of ammonia gas and water vapor, and then subjecting the obtained white corundum particles to calcination, to obtain pretreated white corundum, which is used as is; (2) the pretreated white corundum is mixed in a treatment liquid 2 containing the same molar concentration of Fe 2+ , Fe 3+ , and then left to stand, after which the pretreated white corundum is separated, placed in a mixed atmosphere of ammonia gas and water vapor, subjected to alkali steaming, and then calcined in a protective atmosphere to obtain low-porosity white corundum.

2. The process for preparing low porosity white corundum according to claim 1, characterized in that, In step (1), the ratio of the white corundum particles to the treatment liquid 1 is 1g: 20-40ml.

3. The process for preparing low porosity white corundum according to claim 1, characterized in that, In step (1), the Zr 4 + When the source is excessive, the mass fraction of Zr 4+ When the source is saturated, and the mass fraction of Zr 4+ The mass fraction of Al 3+ 1.2-1.5 times the mass fraction of the source; or, in step (1), the Al 3+ When the source is excessive, the mass fraction of Al 3+ When the source is saturated, and the mass fraction of Al 3+ The mass fraction of Zr 4+ 1.25-1.45 times the mass fraction of the source.

4. The process for preparing low porosity white corundum according to claim 1, characterized in that, In step (1), the Al 3 + The source includes at least one of aluminum chloride, aluminum sulfate, and aluminum nitrate.

5. The process for preparing low porosity white corundum according to claim 1, characterized in that, In step (1), the Zr 4 + The source includes at least one of zirconium chloride, zirconium sulfate, and zirconium nitrate.

6. The process for preparing low porosity white corundum according to claim 1, characterized in that, In step (1), the standing time is 30-50min.

7. The process for preparing low porosity white corundum according to claim 1, characterized in that, In step (1), the white corundum particles are placed above the ammonia water, and then heated to form a mixed gas atmosphere of ammonia gas and water vapor, and then the white corundum particles are subjected to alkali steaming.

8. The process for producing low porosity white corundum according to claim 7, characterized by, The mass concentration of the ammonia water is 15-25%.

9. The process for preparing low porosity white corundum according to claim 7, characterized in that, The heating temperature is 70-85℃, and the alkali steaming treatment time is 40-60min.

10. The process for preparing low porosity white corundum according to claim 1, characterized in that, In step (1), the calcination treatment temperature is 1500-1600℃, and the time is 1.5-2 hours.

11. The process for preparing low porosity white corundum according to claim 1, characterized in that, In step (2), the ratio of the pretreated white corundum to the treatment liquid 2 is 1g: 20-35ml.

12. The process for preparing low porosity white corundum according to claim 1, characterized in that, In step (2), the molar concentration of Fe 2+ , Fe 3+ in the treatment liquid 2 is between 1 and 2 mol / L.

13. The process for preparing low porosity white corundum according to claim 1, characterized in that, In step (2), the Fe 2+ is provided from at least one of ferrous chloride, ferrous sulfate, and ferrous nitrate.

14. The process for preparing low porosity white corundum according to claim 1, characterized in that, In step (2), the Fe 3+ is provided from at least one of ferric chloride, ferric sulfate, and ferric nitrate.

15. The process for preparing low porosity white corundum according to claim 1, characterized in that, In step (2), the pretreated white corundum is placed above the ammonia water, and then heated to form a mixed gas atmosphere of ammonia gas and water vapor, and then the pretreated white corundum is subjected to alkali steaming.

16. The process for preparing low porosity white corundum according to claim 15, characterized in that, The mass concentration of the ammonia water is 15-25%.

17. The process for preparing low porosity white corundum according to claim 15, characterized in that, The heating temperature is 70-85℃, and the alkali steaming treatment time is 30-45min.

18. The process for preparing low porosity white corundum according to any one of claims 1 to 17, characterized in that, In step (2), the calcination treatment temperature is 850-950℃, and the time is 1-1.5 hours.

19. The process for preparing low porosity white corundum according to any one of claims 1 to 17, characterized in that, In step (2), the protective atmosphere comprises any one of nitrogen and argon.

20. The process for preparing low porosity white corundum according to any one of claims 1 to 17, characterized in that, In step (2), the standing time is 30-40min.

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