Study On Preparation Process Optimization And Properties Of Dolomite Brick

The secondary refining technology has advanced remarkably since the21st century andthere is an increasing demand for clean steel and high-grade steel. MgO-CaO refractories havegradually replaced MgO-Cr2O3refractories, which makes dolomite refractory a hotspot ofscientific study again.In this thesis, a study was made on the effect of preparation process optimization ofdolomite brick on its properties to improve the hydration-resistance of dolomite brick, usingsintering dolomite clinker and magnesia as starting materials and the best technical parameter ofpreparation was obtained. We also studied the effect of the content of dolomite fines on thesintering property, mechanical strength, slag-resistance and hydration-resistance of dolomitebrick. The effect of additives on the hydration-resistance of dolomite brick was studied byadding ZrO₂、TiO₂、CeO₂, analyzing samples with XRD and SEM methods and measuring thehydration weight gain rate of samples under natural state, and at the same time, a study wasmade on the effect of impregnating paraffin wax process on the hydration-resistance of dolomitebrick, some significant conclusions were obtained as follows:1.The appropriate preparation process was using semi-refined paraffin wax as bondingagent, sintering at1650℃, and the appropriate grain size gradation was5～3:3～1:1～0:<0.088=24:36:10:30.2. Adding dolomite fines could promote the sintering of dolomite brick and improve itsstrength. With the increasing of dolomite fines, the slag corrosion resistance and penetrationresistance improved but hydration-resistance and high temperature properties declined.3. Adding ZrO₂could promote the sintering and high temperature properties of dolomitebrick and its strength. However, adding ZrO₂would reduce its hydration-resistance; Adding TiO₂could improve its hydration-resistance and1%was the most appropriate content. When thecontent was more than1%, it would reduce its high temperature properties remarkably and itcould not improve its hydration-resistance further more; Adding CeO₂could also improve itshydration-resistance and the content should be above2%.4. The hydration-resistance effect of dolomite bricks impregnated in paraffin wax was betterthan that impregnated in liquid paraffin. The appropriate impregnating paraffin wax process wasimpregnating samples in150℃paraffin wax for5min after being pre-heated at150℃for1h.This impregnating paraffin wax process could prevent samples for almost half a year.