subject: Blending Effect And Its Evaluation Based On The Structural Analysis Of Semicoke [print this page] Coke in containers seems to be in stand, at rest, static. But inside, at the molecular level, it living and dynamic, all the carbon atoms are still in motion, though it cant be seen with the naked eye.
Coke in containers may be a low or a good quality. It depends on the coal used for coking before. Sometimes there is only used a good or only a low quality coal, but mostly there is used a blend of various coals. Such blending gives back various effects. How to check them in laboratory?
In order to evaluate all the effects of low-quality and good-quality coals blended together to make a metallurgical coke, we can analyze thermal decomposition behavior of these coal blends. We can also check the structural features of semicoke samples obtained by the heating of a single coal or coal blend evaluated by the solid-state NMR. Thermal behavior of coal and coal blend can be also examined by the thermogravimetric analysis, and its results show synergistic effects: blending poor-quality low rank coal with good-quality coal tended to promote thermal decomposition reaction, while blending poor-quality high-rank coal will suppress pyrolysis. NMR measurements both with a single pulse excitation mode and with a dipolar dephasing mode give the details of various carbon types distribution, so a fraction of bridgehead aromatic carbon to total aromatic carbon can be evaluated, this being an index of the size of polycondensed aromatic hydrocarbon which would be contained in the samples of semicoke. The size and structural parameters of polycondensed aromatic hydrocarbon unit are being compared between semicoke sample derived single coal and the one from the blended coal. Tthe results clearly indicate synergistic blending effect. Although two different behaviors are being observed for two different coal blends, both cases have positive effects on the aromatic ring size development during the heating process.
