Study On Preparation Of Spinel Contained Cementitious Material Using Magnesite Tailings

This paper aims to solve the Shandong Yexian magnesium mine magnesite tailings problem.Magnesite tailings,slaked lime,?-Al₂0₃ using as raw materials have been tride to synthesize cementitious material containing spinel.The structure and properties of these materials have been studied.The optimal dosage of tailings and the optimum technological conditions have been determined by the orthogonal experiment.This paper will provide guidance for the actual production.To synthetize cementitious material containing MA,this test is based on MgO-CaO-Al₂O₃three phase diagram.Ingredients,sintering temperature and holding time have been determined as the factors of orthogonal experiment table because of the influence on the structure and properties of materials.These raw materials have been crushed,grinded,mixed,molded,sintered and the other process for synthetizing this cementitious materials.Structure of the synthesized materials has been observed by XRD and SEM and semi qualitive analysis of the material has been done.The materials have been made into paste,mortar.Setting time,standard consistency water and strength have been determined.The cementitious materials have been used as binder of the magnesia castable to study the slag resistance and thermal shock stabilityAnalysis of test results have showed that:magnesite tailings can be used to synthesize high temperature cementing material containing magnesium-aluminate spinel.The main mineral phase of this material is MA and CA.The optimum process parameters of synthesizing this material is:ingredient is 4,temperature is1500?,holding time is 2h.When the ingredient is4,the strength of the paste in moisture curing for 7d is about 35-47MPa;the strength of the paste in water curing for 7d is about 36-51MPa.In the mixing point 4,the flexural strength of mortar has reached the international standard of flexural strength of sulphoaluminate cement.The strength of magnesia castable using this cementitious material as binder at 1400?for 3h has been significantly larger than that of this material drying at 110?for 24 h,this indicates that magnesia castable has been sintered at 1400?.The ladle slag resistance test of Magnesia castables shows that the higher spinel content is,the better the slag resistance of magnesia castable performs.