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

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...

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