Denver Sub-A Flotation Cell Mining Gold Denver Sub-A Flotation Cell Mining Gold. -. $16,000. (Salome) Motors: 5 Motors, (4) Motors for each cell, (1) motor for paddles. We purchased this Denver 18 Special for gold processing. This was purchased used, but from a seller which had possession of this machine since it was new. This unit had only run a few hours prior to our purchase.