Research On Erosion Mechanism Of MgO-CaO Material With High CaO Content Used In VOD

In this paper, reaction and erosion of MgO-CaO system refractories insteel slag of VOD has been studied by try-on experiments in VOD andtechnical analyses such as XRD, SEM and phase diagram concerned etc.The results are as follows: Service lining life of MgO-CaO materials isabout 2 times that of magnesia-chrome materials and when the content ofCaO is above 50%, erosion resistance of MgO-CaO samples will beconsiderable higher;With increasing of basicity of slag, the erosion rateof magnesia-chrome materials increased, whereas that of MgO-CaOsamples decreased;C3S and C12A7 is formed by reaction of MgO-CaOwith steel slag in the reaction zone;MgO-CaO materials with high CaOcontent has higher erosion resistance to acidic slag composed of SiO2 andFeO, but reaction of Al2O3 with CaO can produce low melting pointsubstance, so the content of Al2O3 in steel slag should be cut down aspossible;When the content of CaO in steel slag is high, the porosity ofsamples has less effection on the dissolution of CaO of MgO-CaO brick ,on the contrary ,the result was in opposite way and so on. The resultsshowed that MgO-CaO refractories with high CaO content can greatlyimprove the erosion resistance, which would increase the efficiency ofsteel-making and prolong the service life of lining. So it would be usedwidely in VOD in the coming years.The effect of zircon additive on the microstructure of MgO-CaOmaterials with high CaO content, the bonding way and properties of ZrO2and SiO2 with MgO and CaO have been studied .The results are asfollows :(1)The crushing strength of specimens decreases after addingzircon;(2) The effects of the different additions of zircon on the loss rateof MOR (modulus of rupture )of the material are quite different when thethermal shock temperature is 1050℃.The loss rate of MOR of specimensis the lowest when the addition of zircon is 4%;(3) The crystal size ofMgO in matrix to which 4% zircon is added, is bigger than that of thespecimen without zircon addition. With the formation of CaZrO3 , thespecimen has the expansion in volume. SEM observations found that therewere radial microcracks around CZ(CaZrO3) grains. It is the existence ofthese kinds of microcracks that increase the mechanism of consumingenergy which hamper the propagation of cracks and hence the thermalshock stability is higher.(4) The property of hydration resistance isimproved by zircon addition and the best amount of which is 4%...