INVESTIGATION OF PROCESS OF NATURAL GRAPHITE SPHEROIDIZATION

In this paper, the process of spheroidization of natural graphite powders on an original impact-reflecting mill with internal separation of particles was investigated. It was established that the process of spheroidization of natural graphite by impact depends both on the intensity and duration of mechanical activation. For the type of mill used, the critical linear velocity of the impact elements of the mill rotor, at which the graphite particles can be spheroidized, is 45 m/s. An increase in the linear rotational speed of the mill (intensity of impact) leads to a decrease in the average particle size, an increase in particle roundness, but significantly increases product losses. In the process of mechanical activation by impact, it is possible to increase the coefficient of roundness of the graphite particles to an average value of 0.8-0.9, which leads to compaction of graphite powders. The presence of ash impurities has a negative effect on the ability of natural graphite powders to compact. A mechanism is proposed for the process of spheroidization of graphite particles in a shock-reflecting mill. According to the proposed mechanism, at first, small-sized graphite plates are detached and deformed due to impact. As the free energy accumulates, agglomeration of deformed particles into spheres takes place. With increasing processing time, the surface of the particles is smoothed due to their friction with each other and against the wall of the mill. Powders of spherical graphite obtained by the proposed method have shown the possibility of their use as an anode material of lithium-ion batteries. The type of equipment investigated has made it possible to reduce the required number of pieces of equipment from 20 to 12 impact mills per line in comparison with foreign analogues. For citation: Yudina T.F., Blinichev V.N., Bratkov I.V., Gushchina Т.V., Melnikov A.G. Investigation of process of natural graphite spheroidization. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 9-10. P. 48-52