... single-stage separation model comprises down-flow type (CTS), counter flow type (CTN), and semi-counter flow type (CTB), and has a ... all down-flow type (CT2S), upper drum down flow and lower drum counter flow type (CTS-B), and all semi-counter flow type (CT2B ... different ore quality. Optional separation types include down flow, counter-flower, semi-counter-flower, or their combinations from above two ...