Micro-pore dead burned high-calcium magnesite and preparation method thereof

A magnesia-calcium sand and microporous technology, applied in the field of refractory materials, can solve the problems of industrial furnace heat loss, material thermal spalling, high thermal conductivity, and achieve good thermal shock stability, small average pore size, and low thermal conductivity. Effect

Inactive Publication Date: 2019-03-19
UNIV OF SCI & TECH LIAONING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The main crystal phases of magnesium-calcium refractory materials are periclase and pericalcite. At 1000°C, the thermal conductivity of periclase crystals is 6.7W m -1 ·K -1 , the crystal thermal conductivity of calcite is 15W·m -1 ·K -1 , leading to higher thermal conductivity of magnesia-calcium refractory materials, the thermal conductivity of ordinary magnesia-calcium bricks is 4.0W·m at 1000°C -1 ·K -1 Left and right, there are two main problems in the use of magnesium-calcium refractory materials with high thermal conductivity: first, it will cause a large amount of heat loss in industrial kilns; second, the temperature gradient existing inside the refractory material during use produces Thermal stress easily leads to thermal spalling of the material

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0025] A preparation method of microporous magnesia-calcium sand, comprising the steps of:

[0026] 1) Fully digest the light-burned dolomite powder with water in the digester, the amount of water added is 20wt%-40wt% of the light-burned dolomite powder, and the digestion time is 30-60 hours;

[0027] 2) Send the mixed powder of digested light-burned dolomite powder and light-burned magnesium powder into a Raymond machine for co-grinding, and the particle size of the co-milled powder is <0.044 μm;

[0028] 3) Add carbonate micropowder to the co-milled mixed powder and co-mill for the second time in a ball mill for 20 to 40 minutes;

[0029] 4) mixing the co-milled powder obtained in step 3) in a planetary mixer, and the mixing time is 20 to 50 minutes;

[0030] 5) The kneaded material is sent to a ball press machine to form a ball; the green body is naturally dried for 24 to 72 hours; finally, the green body is put into a high-temperature shaft kiln for calcination at a tempe...

Embodiment 1

[0032] A microporous magnesia-calcium sand and a preparation method thereof. 50wt%-55wt% light-burned magnesium oxide powder, 38wt%-40wt% light-burned dolomite powder and 7wt%-10wt% ultrafine magnesite powder are used as raw materials. Add water to the light-burned dolomite powder in the digestion tank for full digestion, the amount of water added accounts for 20wt% to 30wt% of the light-burned dolomite powder, and the digestion time is 30-45 hours; the mixed powder of the digested light-burned dolomite powder and light-burned magnesium powder Send it to the Raymond machine for co-grinding, the particle size of the co-milled powder is <0.044μm; add ultra-fine magnesite powder to the co-milled mixed powder for secondary co-milling in the ball mill, the time is 20-30 minutes; co-milling The powder is kneaded in a planetary mixer, and the kneading time is 35 to 50 minutes; the kneaded material is sent to a ball press to form a ball; the green body is naturally dried for 48 to 72 ...

Embodiment 2

[0035] A microporous magnesia-calcium sand and a preparation method thereof. 50wt%-55wt% lightly burned magnesium oxide powder, 38wt%-40wt% lightly burned dolomite powder and 7wt%-10wt% ultrafine dolomite powder are used as raw materials. Add water to the light-burned dolomite powder in the digestion tank for full digestion, the amount of water added accounts for 30wt% to 40wt% of the light-burned dolomite powder, and the digestion time is 45-60 hours; the mixed powder of the digested light-burned dolomite powder and light-burned magnesium powder Send it to the Raymond machine for co-grinding, the particle size of the co-milled powder is <0.044μm; add ultra-fine dolomite powder to the co-milled mixed powder for secondary co-grinding in the ball mill, the time is 30-40 minutes; co-milled powder Knead in a planetary mixer for 20-35 minutes; send the kneaded material into a ball press to form balls; dry the green body naturally for 24-48 hours; finally put the green body into a h...

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Abstract

The invention provides micro-pore dead burned high-calcium magnesite. The micro-pore dead burned high-calcium magnesite is prepared from the following raw materials: 50 to 70 weight percent of light burned magnesium powder, 25 to 40 weight percent of light-burned dolomite powder and 5 to 10 weight percent of an additive, wherein the additive is carbonate micro-powder and the D50 value of the additive is 50 to 500nm. The micro-pore dead burned high-calcium magnesite has the beneficial effects that 1) the added carbonate micro-powder is decomposed at high temprature to generate carbon dioxide and remain a lot of air pores by adopting a carbonate micro-powder in-situ decomposition method, the added micro-powder is nano-grade micro-powder, almost air pores generated by decomposition are sealedair pores and have a small air pore diameter; components of the added carbonate micro-powder are the same as main components and impurity components are not introduced; 2) the micro-pore dead burnedhigh-calcium magnesite provided by the invention is detected to find out that the volume density is 2.80 to 3.05g/cm<3>, the porosity is greater than 3.0 percent, the ratio of the closed porosity to the total porosity is greater than 60 percent and the average pore diameter is 0.05 to 0.3mum; and 3) the dead burned high-calcium magnesite provided by the invention has the characteristics of low volume density, small average pore diameter, high closed porosity, low heat conductivity, good thermal shock stability and strong washing-out resisting and molten slag erosion resisting capabilities.

Description

technical field [0001] The invention relates to the technical field of refractory materials, in particular to a microporous magnesia-calcium sand and a preparation method thereof. Background technique [0002] Magnesia-calcium refractory materials have become an indispensable and important refractory material in the modern iron and steel industry, especially in out-of-furnace refining, due to their good high temperature stability, corrosion resistance to alkaline slag, and especially their unique ability to purify molten steel. The main crystal phases of magnesium-calcium refractory materials are periclase and pericalcite. At 1000°C, the thermal conductivity of periclase crystals is 6.7W m -1 ·K -1 , the crystal thermal conductivity of calcite is 15W·m -1 ·K -1 , leading to higher thermal conductivity of magnesia-calcium refractory materials, the thermal conductivity of ordinary magnesia-calcium bricks is 4.0W·m at 1000°C -1 ·K -1 Left and right, there are two main prob...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/04C04B35/66C04B35/626
CPCC04B35/04C04B35/62605C04B35/62675C04B35/66C04B2235/321C04B2235/442
Inventor 栾舰李想王春艳蒋晨常君李荣来李荣威王晓东陈军
Owner UNIV OF SCI & TECH LIAONING
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