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A kind of preparation method of activated α-alumina micropowder

A technology of alumina micropowder and alumina fine powder is applied in the field of preparation of active alpha-alumina micropowder, which can solve the problem of unstable sintering performance of refractory body, difficulty in high alpha phase conversion rate and crystallite size, and inability to obtain quality Stable products and other issues, to achieve the effects of excellent surface activity, excellent stability, and reduced grinding time

Active Publication Date: 2018-10-23
湖北斯曼新材料股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, the existing active α-alumina micropowder products generally have the problem of poor matching of "crystallite phase inversion", which makes it difficult to achieve high α-phase inversion rate and crystallite size at the same time, resulting in the failure of the refractory body in application. Due to the defects of unstable sintering performance and poor construction performance, the solution to the above three process difficulties will greatly promote the production and application of activated α-alumina micropowder
[0005] To solve the above problems, it depends on the reasonable selection and use of phase-inversion admixtures (also known as additives) and grinding admixtures (also known as grinding aids). Technology, the adjustment range of its process parameters is narrow, the calcination process is difficult to control stably, and it is impossible to obtain products with stable quality

Method used

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  • A kind of preparation method of activated α-alumina micropowder
  • A kind of preparation method of activated α-alumina micropowder

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Mix 5 kg of composite additives containing boric acid:ammonium fluoride:magnesium chloride=1:3:1 with 1,000 kg of metallurgical-grade industrial γ-alumina raw powder and put them into a refractory sagger. Keep the temperature in the lower rotary kiln for 6 hours, and obtain α-alumina raw powder after natural cooling, the conversion rate is 95.5%, and the primary grain size of the prepared α-alumina raw powder is 0.4 μm.

[0027] Mix 1,000 kg of the α-alumina raw powder prepared above with 0.5 kg of polyethylene glycol (the average relative molecular weight is 600), and grind it in a ball mill for 7 hours, (the grinding medium is preferably alumina ceramic balls), and you can also choose Grinding media with other steel balls to obtain activated α-alumina fine powder with median diameter D50 = 1.08 μm.

Embodiment 2

[0029] Mix 10 kg of composite additives containing borax: ammonium chloride: magnesium chloride = 1:5:2 with 1000 kg of first-grade industrial aluminum hydroxide and put them into a refractory saggar. Rotary kiln at 1250 ° C The α-alumina raw powder was obtained after natural cooling for 12 hours, the conversion rate was 96.4%, and the primary grain size of the prepared α-alumina raw powder was 0.37 μm.

[0030] Mix 1000 kg of the α-alumina raw powder prepared above with 0.6 kg of polyethylene glycol (the average relative molecular weight is 2000), and grind for 12 hours in a ball mill (the grinding medium is preferably alumina ceramic balls), or you can choose other Steel balls grind the medium to obtain activated α-alumina fine powder with median diameter D50=1.03 μm.

Embodiment 3

[0032] Mix 15 kg of composite additives containing borax: ammonium fluoride: magnesium chloride = 1:7:2 with 1000 kg of metallurgical grade industrial gamma-alumina raw powder and put them into a refractory sagger. The α-alumina raw powder was obtained after natural cooling for 6 hours in a rotary kiln with a conversion rate of 97%. The primary grain size of the prepared α-alumina raw powder was 0.45 μm.

[0033] Mix 1000 kg of the α-alumina raw powder prepared above with 1 kg of polyethylene glycol (the average relative molecular weight is 3000), and grind for 10 hours in a ball mill (the grinding medium is preferably alumina ceramic balls), or you can choose other In the steel ball grinding medium, the activated α-alumina fine powder with median diameter D50=1.08 μm was obtained.

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Abstract

The invention discloses a preparation method of active alpha-alumina micro powder. The method comprises the steps that 1, gamma-alumina fine powder or aluminum hydroxide is mixed with a composite additive to be uniform, then calcined in a high-temperature kiln at the temperature of 1250-1450 DEG C for 6-10 h and cooled, and active alpha-alumina raw powder is obtained, wherein the composite additive comprises a mixture of boride, ammonium salt and magnesium-containing inorganic substances or a mixture of fluoride, ammonium salt and magnesium-containing inorganic substances; 2, the obtained active alpha-alumina raw powder and a grinding aid are placed into the grinding device for sufficient grinding, and the active alpha-alumina micro powder is obtained. The method is high in conversion rate, the produced product is small in grain size and high in activity, the production method is stable, and the wide application prospect is achieved.

Description

technical field [0001] The invention relates to a method for preparing a refractory material, in particular to a method for preparing activated α-alumina micropowder. Background technique [0002] Active α-alumina micropowder is an important raw material for high-performance unshaped refractories and shaped refractory products. Its performance mainly comes from its small grain size, large specific surface area, high surface activity, and easy sintering under high temperature conditions; active oxidation The excellent performance of aluminum powder makes it widely used in many medium and high-grade refractory materials, such as unshaped refractory materials for iron troughs in ironmaking, ladle working lining and ventilation system, slag retaining weir for tundish, continuous casting three Functional refractory materials such as large pieces. [0003] The production of activated α-alumina micropowder requires high-temperature calcination to convert γ-phase alumina crystals i...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/66C04B35/626
CPCC04B28/06C04B35/6261C04B35/62645C04B35/66C04B2111/00431C04B14/303C04B14/062C04B20/008C04B2103/302
Inventor 刘学新李文
Owner 湖北斯曼新材料股份有限公司