Processing And Properties Of Hot Repair Materials Prepared By Used Magnesia And Magnesia Aluminum Spinel Bricks

Based on the systematic study of the chemical composition,microstructure and phase changes of used magnesia bricks and RH converter magnesia-alumina spinel,and the preparation of converter hot repair materials using magnesia bricks and magnesia-alumina spinel as the main raw materials.The main research contents are the influences of the main raw materials,particle gradation,type and addition of binding agent on the microstructure and properties of the hot repair material and the related mechanisms.The main results of this thesis are as follows.(1)The surface of the used magnesia brick was almost not eroded,while the surface of the RH converter magnesia aluminium spinel was eroded to a greater extent.The analysis of surface and internal chemical composition and microstructure showed that the refractory chemical composition and physical structure did not change much after use.Therefore,the used magnesia bricks and RH converter magnesia-aluminium spinel can be used as raw material for the preparation of converter hot-state repair materials.The erosion analysis results show that the eroded and uneroded layers of RH converter magnesia-alumina spinel differ greatly in elemental content,of which the eroded layer contains more elements such as silica-aluminiumiron,while the uneroded layer contains more magnesium elements.(2)The research of influences of raw material ratio,particle gradation,binding agent type and the amount added on bulk density,porosity,compressive strength,flexural strength,thermal shock resistance performance of the hot state repair material shows that when the main raw material is used after the magnesium brick,magnesium brick added to 80wt%(1-3mm40wt%,0-1mm 20wt%,≤0.074 mm 20wt%),magnesium sand added to 10wt%,metal silica powder added to,the best performance of the converter hot-state repair material is achieved with 10wt% of modified bitumen and 28wt% of modified bitumen.When the main raw material is magnesia-aluminium spinel,the best performance of the converter hot state repair material is achieved when the amount of magnesia-aluminium spinel added is 70wt%(40wt% for 1-3mm,20wt% for 0-1mm and 20wt% for ≤0.074mm),the amount of magnesium sand added is 20wt%,the amount of metallic silica powder added is 10wt% and the amount of modified bitumen added is 26wt%.(3)In the modified bitumen by adding phenolic resin,by adjusting the type and content of binding agent,the preparation of converter hot state repair material research found that when the main raw material is used after the magnesium brick,magnesium brick addition amount is80wt%(1-3mm 40wt%,0-1mm 20wt%,≤0.074 mm 20wt%),magnesium sand addition amount is 10wt%,metal silica powder addition amount is 10wt%,adding 3wt% phenolic resin,the The best performance of the hot state repair material is achieved when 27wt% of modified bitumen is added.The best performance was achieved when the main raw material was magnesiaaluminium spinel,with 70wt% of magnesia-aluminium spinel(40wt% 1-3mm,20wt% 0-1mm and 20wt% ≤0.074mm),20wt% of magnesia sand,10wt% of silica metal powder,3wt% of phenolic resin and 27wt% of modified bitumen.The addition of waste brick in this work,60%-90%,allows for the bulk application of solid waste,while protecting the environment and achieving a high value use of the used refractory.The thesis research is expected to achieve high value utilization of bulk low-order solid waste under normal conditions and can provide a feasible solution for the treatment of post-use refractory materials.