The Modification Of Middle Temperature Coal-tar Pitch And Its Application To Carbon Ramming Mix

Carbon ramming mix is one of important refractories for blast furnace. In this study, middle temperature coal-tar pitch as binder is modified by p-tert benzaldehyde, modified pitch and silicon raw material are joined carbon ramming mix, SiC whisker is in situ formation in, the performance of carbon ramming mix and thus improve.Basis of electrophilic substitution reaction, the chemical crosslinking and vacuum distillation methods was used, the middle temperature coal-tar pitch was used as the material, the p-tert benzaldehyde was used as modifier, the p-toluene sulfonic acid was used as catalyst, the middle temperature coal-tar pitch was modified under argon atmosphere and vacuum,the effect of reaction conditions was researched. The result show that, the modifier dosage, the reaction temperature,the reaction time and the reaction pressure has greater effect on the performance of pitch. The high-quality that its softening point is 151.5℃, its carbon yield 75% is prepared under the reaction conditions: modifier/pitch 1:5,the the catalyst 5%, the reaction temperature 180℃, the reaction pressure 20kPa, the reaction time 8 h.The effects of modification of middle temperature pitch and tar the raw material composition on carbon ramming mix have been studied. The result show that, for carbon ramming mix when pitch 6% , tar 10% joined, carbon ramming mix has the optimum performance.The effect of silicon powder,catalyst,nano-silica,fused silica,silicon metal on on carbon ramming mix have been studied. The following conclusions can be drawn. After adding silicon powder, SiC whisker is in situ formation in the sample at 1350℃and 1550℃.The yield of the SiC whisker is higher at 1550℃。After adding catalyst,The yield of the SiC whisker is higher than blank sample,but the sample,s performance is poor because of more volatile ethanol in catalyst. In comparison with the sample which add silicon powder, the SiC whisker is unease in situ formation in the sample which add silica white, and ease in situ formation in the sample which add fused silica and silicon metal, the sample which add silicon metal has the optimum performance.The thermal conductivity of sample which formation SiC whisker is higher than that blank sample.