Teetered Bed Separators (TBS) perform under the effect of numerous operational parameters of importance such as teeter water flowrate (TW) and the pressure set point (SP), which directly influence the performance figures in terms of cut size (D-50), cut density (rho(50)), and efficiency (Ep). Adjustment flexibility of TBS enables it an important tool to be used in mineral and coal processing and classification applications. The aim of this study is to investigate density-based separation and size classification performance of TBS when an industrial high-ash lignite sample was processed. Results showed that separation performance was better at higher SP values, and increasing TW was providing better separation performances especially at higher rho(50) values. At low SP values, TW was observed to play a critical role in separation performance. Separation performances (Ep) with the size fractions of +2000 mu m, +1000 mu m, +500 mu m, and +200 mu m were obtained as 0.08, 0.12, 0.14, and 0.16, respectively. On the other hand, classification performance is observed to be better at low SP values and could also be manipulated by TW.