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Preparation method of compact magnesia-alumina spinel refractory aggregate

A magnesia-aluminum spinel and refractory aggregate technology, applied in the field of refractory materials, can solve the problems of affecting the interface properties, low density of magnesia-aluminum spinel, reducing the activation energy of ion diffusion, etc. Good thermal shock performance, suitable for large-scale industrial production, and stable high temperature strength

Active Publication Date: 2015-06-24
CHINA UNIV OF GEOSCIENCES (BEIJING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to solve the problem that the density of magnesium aluminum spinel synthesized by one-step method is not high, and the energy consumption of magnesium aluminum spinel synthesized by two-step method is relatively high. CaO produced by pyrolysis of calcium hydroxide in lime water and MgO and Al in synthetic materials 2 o 3 Form intrusive and displacement solid solutions, although the amount of solid solution is very small, see the attached instructions figure 2 , but it concentrates on the crystal surface and grain interface, which affects the interface properties and reduces the activation energy of ion diffusion, thereby promoting the sintering of spinel; using low-temperature pre-calcination and then impregnating to introduce a small amount of CaO compared to the initial raw material ingredients Directly introducing a trace amount of CaO can make the distribution of calcium ions more uniform. At the same time, the key point is that when a trace amount of CaO is directly introduced into the initial raw material ingredients, CaO will preferentially interact with Al 2 o 3 The reaction produces calcium aluminate, and most of the calcium aluminate will be hydrolyzed, which affects the use effect and life of the refractory aggregate. After pre-burning, MgO has been combined with Al 2 o 3 The reaction produces magnesium aluminum spinel, and after the introduction of CaO, it mainly interacts with MgO and Al 2 o 3 Form intrusive and displacement solid solutions, play a role in promoting sintering, reduce the formation of calcium aluminate), reduce the temperature of the two-step synthesis of magnesium aluminum spinel, and reduce the temperature of the two-step synthesis of magnesium aluminum spinel The energy consumption of stone is used to synthesize high-density magnesia-alumina spinel aggregate, and a preparation method for dense magnesia-alumina spinel refractory aggregate is proposed

Method used

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  • Preparation method of compact magnesia-alumina spinel refractory aggregate
  • Preparation method of compact magnesia-alumina spinel refractory aggregate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Using light-burned magnesite and α-alumina powder as raw materials, according to a certain proportion (the addition of light-burned magnesite is 28.33wt.%, the addition of α-alumina powder is 71.67wt.%), mixed ball milling, It is formed into a green body of 200mm×80mm×110mm by dry pressing with a hydraulic press. The molding pressure is 100MPa, and then it is pre-fired at 1200°C for 2 hours. After taking it out, it is crushed with a jaw crusher to a particle size of about 15mm, and the block is immersed in acetic acid. In the saturated solution of calcium, the impregnation time is 1h, take it out and dry it naturally for 24 hours, then burn it at 1650℃.

[0016] The prepared dense magnesia-aluminum spinel refractory aggregate has a density of 3.6 g cm -3 , The apparent porosity is 1.0%.

Embodiment 2

[0018] Use light-burned magnesite and γ-alumina powder as raw materials, mix according to a certain proportion (the amount of light-burned magnesite added is 27wt.%, and the amount of γ-alumina powder added is 73wt.%), mixed ball mill, and passed through a hydraulic press Dry press into a green body of 200mm×80mm×110mm, the molding pressure is 80MPa, then pre-fired at 1200°C for 2 hours, take it out and crush it with a jaw crusher until the particle size is about 15mm, then immerse the block material in a saturated lime aqueous solution In the process, the impregnation time is 2h, take it out and dry it naturally for 24 hours and then burn it at 1600℃.

[0019] The prepared dense magnesia-aluminum spinel refractory aggregate has a density of 3.5 g cm -3 , The apparent porosity is 1.2%.

Embodiment 3

[0021] Using light-burned magnesite and α-alumina powder as raw materials, according to a certain proportion (the addition of light-burned magnesite is 28.33wt.%, the addition of α-alumina powder is 71.67wt.%), mixed ball milling, It is formed into a green body of 200mm×80mm×110mm by dry pressing with a hydraulic press, the forming pressure is 100MPa, and then it is pre-fired at 1000°C for 2 hours, and it is taken out and crushed to a particle size of about 10mm by a jaw crusher, and the block is immersed in acetic acid In the saturated solution of calcium, the impregnation time is 2 hours, take it out and dry it naturally for 24 hours, then burn it at 1600°C.

[0022] The prepared dense magnesia-aluminum spinel refractory aggregate has a density of 3.55 g·cm -3 , The apparent porosity is 1.5%.

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Abstract

The invention relates to a preparation method of compact magnesia-alumina spinel refractory aggregate and belongs to the technical field of refractory materials. According to the preparation method, light burned magnesite powders and aluminum oxide powders are used as raw materials and blended according to a certain proportion, the raw materials are subjected to mixing, ball milling, forming, pre-burning and breaking, saturated lime water or a saturated solution of calcium acetate is sprayed on surfaces of bulk materials, or the bulk materials are immersed into the saturated lime water or the saturated solution of the calcium acetate, and then the bulk materials are taken out for natural drying and then sintered at high temperatures. The compact magnesia-alumina spinel refractory aggregate is large in density, high in compactness, good in thermal shock resistant performances and highly stable in reducing atmosphere and alkaline environment, and the compact magnesia-alumina spinel refractory aggregate has wide application prospects in fields of refractory material products, refractory castables and the like.

Description

Technical field: [0001] The invention relates to a preparation method of dense magnesium-aluminum spinel refractory aggregate, belonging to the field of refractory materials. Background technique: [0002] Magnesium-aluminum spinel is a very important refractory material, which has many superior properties, such as high melting point (2135°C), low thermal expansion, high heat resistance and corrosion resistance. Therefore, magnesia-aluminum spinel refractory products are widely used in cement, glass, non-ferrous smelting and steel industries, and are even regarded by many foreign experts as the "mullite" of the 21st century. Magnesium-aluminum spinel refractory aggregate is a new type, high-efficiency, clean, and environmentally friendly green product, and it is an important refractory raw material to replace magnesium-chromium products (with strong carcinogenic effect) in a wide range of fields. With the increasing intensity of national environmental protection and the pha...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/66
Inventor 易帅黄朝晖房明浩刘艳改
Owner CHINA UNIV OF GEOSCIENCES (BEIJING)
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