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Preparation method of high-purity microcrystalline alpha-phase aluminum oxide

A phase alumina, high-purity technology, used in chemical instruments and methods, aluminum compounds, inorganic chemistry, etc., can solve problems such as changing crystal growth, increasing the difficulty of process control, and unclean sodium oxide removal, reducing energy consumption and reducing energy consumption. The effect of high cost, high process stability and convenient production and operation

Pending Publication Date: 2022-07-29
湖北晶耐新材料有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this production process has the following disadvantages: First, sodium oxide is removed in the form of steam after it is released in the high temperature zone, but because there are different temperature zones in the thermal kiln, when the sodium oxide steam flows through the low temperature zone, part of the sodium oxide The steam will condense and return to the raw material again, causing the sodium oxide to be not removed cleanly; secondly, the admixture used to remove the sodium oxide impurity will also change the crystal growth while promoting the α-phase conversion rate, making it difficult to prepare crystals. Microcrystalline α-alumina powder with uniform particle size increases the difficulty of process control and ultimately affects the quality stability of the microcrystalline α-phase alumina product obtained by calcination

Method used

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  • Preparation method of high-purity microcrystalline alpha-phase aluminum oxide
  • Preparation method of high-purity microcrystalline alpha-phase aluminum oxide

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Spread the γ-phase alumina fine powder on the conveyor belt with a thickness of 4mm, and preheat it to 75°C in the mesh belt kiln; the preheated fine powder is sprayed into a muddy state by a water curtain rich in carbon dioxide and then flows into the mixing tank , stir for 20 minutes to obtain a uniform slurry, the solid content of the slurry is 25wt%, and the slurry temperature is 35 ° C; The filter cake is sent to a tunnel kiln for pretreatment, then calcined to 1250° C. and kept at this temperature for 6 hours, and naturally cooled to obtain microcrystalline α-phase alumina.

Embodiment 2

[0024] The γ-phase alumina fine powder is spread on the conveyor belt with a thickness of 3mm, and preheated to 65°C in the mesh belt kiln; the preheated fine powder is sprayed into a muddy state by a water curtain rich in carbon dioxide and then flows into the mixing tank , stirring for 25 minutes to obtain a uniform slurry, the solid content of the slurry is 35 wt%, and the slurry temperature is 45 ° C; The filter cake was sent to a tunnel kiln for pretreatment, then calcined to 1350° C. and kept at this temperature for 4 hours, and naturally cooled to obtain microcrystalline α-phase alumina.

Embodiment 3

[0026] Spread the γ-phase alumina fine powder on the conveyor belt with a thickness of 5mm, and preheat it to 60°C in the mesh belt kiln; the preheated fine powder is sprayed into a muddy state by a water curtain rich in carbon dioxide and then flows into the mixing tank , stirring for 25 minutes to obtain a uniform slurry, the solid content of the slurry is 40wt%, and the slurry temperature is 30°C; the slurry is sent to a slab filter press for pressure filtration, and the filter cake obtained after pressure filtration contains water The rate is 30wt%; the filter cake is sent to a tunnel kiln for pretreatment, then calcined to 1350°C and kept at this temperature for 5 hours, and naturally cooled to obtain microcrystalline α-phase alumina.

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Abstract

The invention provides a preparation method of high-purity microcrystalline alpha-phase aluminum oxide. The preparation method comprises the following steps: firstly, preheating gamma-phase aluminum oxide fine powder in a mesh belt kiln; spraying the preheated fine powder into slurry through a water curtain rich in carbon dioxide, enabling the slurry to flow into a stirring barrel, and uniformly stirring to obtain slurry; feeding the slurry into a filter press, and carrying out filter pressing to obtain a filter cake; and finally, feeding the filter cake into a high-temperature kiln for pretreatment, calcining to 1200-1400 DEG C, carrying out heat preservation reaction at the temperature, and naturally cooling to obtain the high-purity microcrystalline alpha-phase aluminum oxide. According to the preparation method, impurity removal is stable and does not remain, the content of sodium oxide can be reduced to 0.05 wt% or below, the conversion rate of alpha-phase aluminum oxide is kept to be 97% or above, the grain diameter of the obtained microcrystalline alpha-phase aluminum oxide is within the range of 0.3-1 micrometer, and according to the combination of different calcination temperatures and heat preservation time, the content of the alpha-phase aluminum oxide is reduced to be more than 10%. Uniform microcrystalline alpha alumina with different grain diameters can be obtained; the preparation method is high in process stability, convenient to produce and operate and low in manufacturing cost.

Description

technical field [0001] The invention belongs to the technical field of fine chemical industry, and relates to a preparation method of microcrystalline α-phase alumina. Background technique [0002] Microcrystalline α-phase alumina is the main raw material for high-performance refractories and alumina-based special ceramic materials. Microcrystalline α-phase alumina has extremely high temperature resistance, wear resistance and insulation properties. The micropowder prepared by grinding microcrystalline α-phase alumina forms a ceramic bond with other raw materials in the refractory material under high temperature conditions, which strengthens the mechanical properties, erosion resistance, wear resistance and other properties of the refractory material. Microcrystalline α-phase alumina makes alumina-based special ceramic products with excellent properties such as easy sintering, high strength, high wear resistance, high insulation, and corrosion resistance. [0003] In the ac...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/021
CPCC01F7/021C01P2004/62C01P2006/80
Inventor 刘学新李文熊明继
Owner 湖北晶耐新材料有限公司