• Evaluation of the four inch compound water cyclone as a gold concentrator using radiotracer techniques

      Walsh, D.E. (University of Alaska Mineral Industry Research Laboratory, 1985)
      A 4 inch compound water cyclone, CWC, was tested to evaluate its gold recovery characteristics when processing minus 3/16 inch, run-of-pit, placer material. Neutron activated placer gold particles (841 to 37 microns) were used as radiotracers concentrator recovery; a procedure believed unique to this study. The effect on gold recovery of gold size and shape, feed pulp density, feed pressure, vortex finder clearance (VFC), CWC cone type, top-size of the feed solids, presence or absence of heavy minerals in the feed, and the quantity of -400 mesh slimes in the feed was investigated in over 300 tests. CWC concentration ratio and the top-size of the underflow solids were both affected by cone type, VFC, and feed pressure. Gold recovery was significantly affected by gold size, gold shape, and concentration ratio. These effects are complex, since significant size-concentration ratio and size-shape interactions exist. Radiotracer techniques showed gold particles had a residence time within the CWC of approximately one second, thus challenging the three stage, segregated bed theory of CWC concentration. This work suggests CWC gold recovery is a function of particle size and shape, and the water flow rate through the CWC. "Bed density" is considered important only as a thin, protective layer, which shields coarser gold particles from the entraining currents and facilitates their movement through the CWC.