Preparation And Characterization Of Coal Tar Pitch Binder

Taphole clay is a functional refractory material used to block the taphole of blast furnace.It is composed of refractory aggregate and binder and mainly used in the steel industry.The binder plays a very important role in the taphole clay.The performance of the taphole clay is closely related to the property of binder.The performance of the taphole clay affects the running of the blast furnaceand the ourput of steel.At present,the T-60 taphole clay binder produced abroad has excellent performance.Generally,coal tar and resin are used as a binder in domestic.But both of them have some drawbacks.The coal tar is cheap and easy to be obtained in China..The coal asphalt with low softening point and excellent performance would cover the shortages of coal tar and resin used as a binder,which in turn improves the performance of taphole clay.This would not only make a full use of the advantages of resource in China,but also reduce the dependence on foreign products.In this work,three methods were used to prepare taphole clay binder with a softening point of 25 ?.The effects of process parameters of each technology on the performance of refined asphalt and taphole clay binder were studied.Moreover,the optimum process conditions were determined.The performance of the coal tar pitch prepared under the optimum process conditions was compared with that of the domestic general bonder and foreign high-quality binder.It was found that the taphole clay binder prepared under the optimal process conditions reached a better level.The main contents and results are summarized as following:(1)Vacuum distillation is a one-step preparation of taphole clay binder.The effects of distillation temperature and distillation time on the performance of asphalt binder were investigated.The results showed that the asphalt softening point,coking value and QI content of asphalt binder increased gradually with the increase of distillation time and heat treatment temperature.Considering the softening point of the industrial taphole clay binder used at 25 ?,the coke yield of binder ZZ-1 prepared by this method was 23%,the QI content was 2.05%and the bond strength was 28.04 MPa.(2)Carbon black modified coal asphalt thermal polymerization is a two-step preparation of taphole clay binder.The influences of thermal polycondensation temperature,thermal polycondensation time and ratio of carbon black on the performance of refined asphalt were investigated.The results indicated that the softening point,the coking value and the QI content of the refined asphalt increased,while the ? resin content increased firstly and then decreased with the increase of thermal polycondensation temperature,thermal polycondensation time and the ratio of carbon black.The second step was to adjust the softening point and determine the optimum process conditions of additive ratio and mixing time.We found:the coke yield of optimal binder ZZ-2 prepared by this method was 32.21%,the QI content was 6.5%,the softening point was 25 ? and the bond strength was 130.84 MPa.(3)Propane deasphalted resid modified coal asphalt thermal polymerization is a two-step preparation of taphole clay binder.The impacts of thermal polycondensation temperature,thermal polycondensation time and propane deasphalted resid ratio on the performance of refined asphalt were investigated.The results displayed that the softening point,the coking value and the QI content of the refined asphalt increased,while the ? resin content increased firstly and then decreased with the increase of thermal polycondensation temperature,thermal polycondensation time and the ratio of propane deasphalted raised.The second step was to adjust the softening point and determine the optimum process conditions of additive addition and mixing time.The coke yield of optimal binder ZZ-3 prepared by this method was 36.62%,the QI content was 6.44%,the ? resin content was 17.57%,the softening point was 25 ? and the bond strength was 180.92 MPa.(4)ZZ-1,ZZ-2 and ZZ-3 were compared with homemade general binder MP-4 and high quality foreign binder T-60.The characterization results showed that ZZ-3 had the best performance and chemical structure.Its performance was very similar to foreign high-quality T-60.The results showed that the performance of the ZZ-3 has reached a better level by the method of propane deasphalted resid modified coal asphalt thermal polymerization.