New advance in instruments, computers and numerical methods have greatly increased in order to conduct the research efforts in coals. For numerical research work, Computational Fluid Dynamics (CFD) plays a key role to explain these developments of different coal chemistry steps including devolatilisation, volatile combustion and reforming, char oxidation and char gasification. In this research work, the authors investigate numerically the primary reactions of coal volatiles including the soot formation mechanism. Comparison between detailed mechanism without soot and soot model is provided. The effects of O2/CO2 concentration for the soot model for O2/CO2 gasification are also reported.