Energy transfer in mechanochemical treatment of POPs in a horizontal ball mill

Abstract

In recent years, mechanochemical (MC) treatment of persistent organic pollutants (POPs) has received extensive research attention. As an easy-to-use and non-combustion treatment technology, MC is known for its high destruction rate for chlorinated, brominated, and even fluorinated pollutants. Consequently, there is great potential for large scale application of MC for POPs treatment. However, due to the limited treatment capacity, planetary ball mills are not suitable for full scale MC treatment. On the other hand, a horizontal ball mill is proposed in this study to replace the planetary ball mill in MC treatment. The kinetic model for the trajectory of a single milling ball in two types of devices and the local energy transfer model during the ball collision were established. The effective collision energy was also investigated and compared quantitatively in the two devices. The results indicated that the energy density of the planetary ball mill was higher than that of the horizontal ball mill. For the horizontal ball mill, the effective collision energy increased with the increasing roller radius, and there was an optimal revolving speed for ball milling. The low energy density of the horizontal ball mill could be compensated by high charge ratio and extended milling time. Besides, since the energy utilization efficiency and treatment capacity of the horizontal ball mill is much higher than that of the planetary ball mill, the horizontal ball mill is more feasible for large scale MC treatment of POPs.