Magnesite (dead burned high-calcium magne-site) refers to a magnesite-calcium refractory raw material prepared by a synthetic process according to a given CaO/SiO2 ratio. Also known as high calcium magnesia. Used to make magnesia-calcium bricks. With the increase of the calcination temperature, the C4AF can be distributed between the periclase crystal grains gradually accumulate to the corner gap between the periclase crystal grains, the magnesia-calcium sand will increase the high-temperature strength of the brick. Although the calcium content of magnesia-calcium sand is much higher than that of ordinary magnesia brick sand, because there is no free CaO3, the brick making process is the same as ordinary magnesia brick, sulfite pulp waste liquid can still be used as binder.
The main mineral composition is periclase, followed by dicalcium silicate (C2S) a small amount of tetracalcium aluminate (C4AF), dicalcium ferrite (C2F), etc., which are dark brown blocks, with a density of 3.50g/cm3, CaO /SiO2 is 2~3, with Al2O3<1% without free calcium oxide. CaO SiO2 have been synthesized into high melting point mineral dicalcium silicate dicalcium silicate, Al2O3 generates low melting point mineral C4AF, which can affect the high temperature mechanical properties of the brick, its high temperature load softening temperature decreases with the increase of the Al2O3 content in the brick .
With the increase of the calcination temperature, the C4AF can be distributed between the periclase crystal grains gradually agglomerate to the corner gap between the periclase crystal grains, resulting in the increase of the high temperature strength of the brick. Although the calcium content of magnesia-calcium sand is much higher than that of ordinary magnesia brick sand, because there is no free CaO3, the brick making process is the same as ordinary magnesia brick, sulfite pulp waste liquid can still be used as binder.