This passable we will talk about the the last two problems about magnesia calcium carbon bricks（refractory fire brick）. This problem is about Waterproofing of free CaO and Carbonization of molten steel.
3. Waterproofing of free CaO
Although CaO, as an alkaline material, has the ability to purify molten steel, excellent slag resistance, thermal stability, etc., the main disadvantage of CaO is that it absorbs water in the air and hydrates. Its hydration proceeds according to the following chemical reaction equation in Magnesite Bricks Factory.
CaO+H2O→Ca(OH)2+(16×4.18KJ)
CaO hydration is still a worldwide recognized problem, for which many researchers have done a lot of research, and also obtained many methods of CaO water repellency. Among them, the methods include covering calcium-containing products in Magnesite Bricks Factory from the perspective of technology, such as phosphoric acid treatment, surface dipping wax, etc.; from the perspective of sintering, the CaO grains grow up to form relatively stable grains; from the perspective of admixtures, the introduction of Oxides such as ZO2 and CaO form compounds with better boiling hydration properties.
However, in resin-bonded magnesium-calcium-carbon refractories in Magnesite Bricks Factory, because the resin decomposes violently before 510 °C, CaO can be hydrated before this temperature.
4. Carbonization of molten steel
With the increase in the demand for pure steel, low carbon steel and ultra-low carbon steel, due to the high carbon content (10%-20%) of traditional carbon-containing refractories in Magnesite Bricks Factory, the probability of adding carbon to molten steel during use also increases. , which has gradually become a problem to be considered, so traditional carbon-containing refractories have been difficult to use under clean steel smelting conditions due to their carbon content. And from the perspective of energy saving and environmental protection, the increase in energy consumption and the waste of graphite resources caused by the high thermal conductivity of high carbon content refractory materials also promotes carbon-containing refractories in Magnesite Bricks Factory to become low-carbon and non-carbonized.
Because magnesia-calcium-carbon bricks also contain a certain amount of carbon, similar to magnesia-calcium-carbon bricks, magnesia-calcium-carbon bricks in Magnesite Bricks Factory also have the possibility to increase carbon in molten steel, so controlling the carbon content is also a very important task. The proportion of carbon content should generally be controlled at about 2%-6%. This is because the first consideration is to increase the carburization of molten steel, as well as the decarburization of the magnesia-calcium-carbon brick itself, which will reduce the service life, and the more graphite is added, the more magnesia-calcium products in Magnesite Bricks Factory are. The compressive strength and bulk density are generally lower, and the strength of carbon-free magnesium-calcium products is generally higher than that of carbon-containing magnesium-calcium products.
