Dry cleaning of pulverized coal using a novel rotary triboelectrostatic separator (RTS)

Coal cleaning is often conducted using wet physical separation processes such as heavy medium vessels or spirals at coal preparation plants to remove impurities such as ash, sulfur, and mercury. However, the resultant clean coal product still contains a significant amount of impurity due to the fact that impurities are not well liberated from coal particles ranging from several millimeters to inches in size at which wet cleaning processes take place. A cleaner coal product can be obtained if a dry process is avaialble to further clean pulverized and thus better liberated fine coal at the power plant prior to its combustion. In this study, a novel rotary triboelectrostatic separator (RTS) was investigated for its application to dry cleaning of fine coal samples acquired from the power plants in the state of Illinois. The proprietary RTS is characterized by an innovative high-efficiency rotary charger, charger electrification, laminar air flow, etc. Compared to existing triboelectrostatic separators, the RTS offers significant advantages in particle charging efficiency, solids throughput, separation efficiency, applicable particle size range, etc. Important process parameters such as charger rotation speed, injection and co-flow rate, and feed rate were investigated for their effects on separation performance.