Study On Magnesia-Spinel Refractories Used In RH Snorkel

With the fast development of technology and economy in our nation,the requirement for high-quality steel is growing greatly.RH device is one of the most important refining equipment to refine high-quality clean steel.Nowadays,magnesia-chrome refractory is prevalent in RH snorkel lining.However,due to the pollution of chrome containing refractory,it's urgent to develop new chrome-free or low-chrome materials to replace magnesia-chrome refractory.With great mechanical properties,good working properties in high temperature and excellent slag resistance,magnesia-spinel refractory is an ideal alternation to be used in the lining of RH snorkel.But there are still a lot of works to do to reach the same service life as magnesia-chrome refractory.High-purity sintered magnesia,fused magnesia and three kinds of sintered magnesia-alumina spinel were used as raw material,while sulfite waste liquor was employed as the binder to find proper preparing condition.Cr₂O₃,Fe₂O₃ and PSZ-ZrO₂ were used as addictives to improve the properties of magnesia-spinel refractory.Conclusions were obtained as followed:1.Sintering temperature has a great influence on sintering properties.High sintering temperature would accelerate grain-growth and sintering process of magnesia-spinel refractory;2.All of spinel composition,spinel particle size and the content of spinel would lead to different form and number of microcracks in the microstructure,thus caused different properties of magnesia-spinel refractory used in RH snorkel.As a result,it's important to control the form and number of microcracks in magnesia-spinel refractory;3.The proper preparing conditions of magnesia-spinel refractory used in RH snorkel were: using magnesia rich spinel which contains 50wt% Al2O3 as raw material,the better particle size of spinel was 1-0mm,spinel content was 16wt%,the briquetting pressure was 180 MPa and the specimens were sintered at 1650?×3h;4.Adding addictives could improve the properties of magnesia-spinel refractory greatly.Cr₂O₃ micropowder would improve the properties of slag resistance and Hot MOR by forming solid solutions,while Fe₂O₃ would accelerate sintering process and obtained a better mechanical property.Meanwhile,PSZ-ZrO₂ was found to have a good influence on mechanical property and thermal resistance due to phase transformation toughening.5.By comparing experiment with magnesia-chrome refractory used in RH snorkel,we draw a conclusion that magnesia-spinel refractory can replace magnesia-chrome refractory to apply in the lining of RH snorkel.