Numerical simulation of ball milling reactor for novel ammonia synthesis under ambient conditions

The investigation models an alternative ammonia production method compared to the Haber-Bosch method. The operating parameters of proposed process, which successfully synthesized ammonia with competitive yield, were 45 °C and 1 bar, which is significantly lower than the Haber-Bosch process. A study was made on the impact and contact behavior of the planetary ball mill to understand the movement of steel balls and iron particles inside the reactor vessel to improve the synthesis process. The EDEM software, based on discrete element method (DEM), was used to understand the internal behavior of a planetary mill. Balls and particles were loaded at a ratio of 1:20, i.e., 500 g of steel ball diameter is 25 mm, and 24 g of iron particles diameter is 0.25 mm in reactor. Contact and energy released by balls and particles as a function of mill speed were compared with the experimental correlation of adsorbed nitrogen. The correlation with the experimental data showed satisfactory agreement with present numerical simulation. This work is the first step towards realistic scaling of the system and vertical mill is not a common practice on an industrial scale, this work will use experimental data to create and validate a vertical ball mill model.