Study On Intensification Of Carbonization Consolidation Of Formed Coke With Coal Tar Pitch As Binder

The preparation of formed coke is the main method for recycling coke powder generated in the process of production, transportation and use of coke, and coal tar pitch binder is one of the most effective binders for preparation of formed coke. However, large amounts of pores caused by volatilization of coal tar pitch at high temperatures will make carbonization skeleton structure loose, therefore the improvement of the strength of formed coke is limited. In this study, the consolidation strength of formed coke is improved effectively through adding ultra-fine grinding coke powder in coal tar pitch as filling material and refining the coal tar pitch. When the coal tar pitch grain size was-0.150mm, and the same mass of ultra-fine grinding coke powder with volume average particle size of8.6μm was added into the coal tar pitch, the compressive strength of formed coke increased from14.3Mpa to more than19.7Mpa.The technology parameters for adding ultra-fine grinding coke powder into coal tar pitch have been studied and optimized. The best condition for preparing formed coke should be as followings:the molding pressure35Mpa, water content13%to15%, the addition of BJ no less than2%, the content of-0.150mm coal tar pitch particles betweenl2%and14%, the volatilization temperature370℃～395℃, volatilization time no less than15min, carbonization temperature600℃～800℃and carbonization time no less than30min.Microstructure analysis showed that the formed coke structure after added ultra-fine grinding coke turned closely. There was no apparent pore but only some small pores. The pore distribution was uniformed, and the pores were filled with amounts of micro-particles. Ultra-fine grinding coke powder can significantly reduce the gap between the coke particles, and skeleton structure formed by asphalt carbonization was filled and as bridge chains between the coke particles to strengthen the carbonization consolidation.According to the China metallurgical coke quality standards, the formed coke prepared in this study is in full compliance with these standards, and some indicators including the volatile matter content, ash content, sulfur content and porosity are far more better than the requirements for metallurgical coke of grade Ⅱ but close to the requirements for the product of grade Ⅰ. Compared with cokes prepared by most of the other technologies, the coke prepared in this study has higher strength.