4. Results and discussion
4.1. Flotation
Hidden Valley primary ore was floated during a flotation time of 10 min with the mass recovery of flotation concentrate reaching 6.8%. Fig. 5 shows the grade-recovery plots of flotation concentrate for the four elements Au, Ag, Fe, and S. At the baseline flotation (in the absence of any cyanide species), Au displayed good floatability reaching a recovery of 93.7% and a concentrate grade of 20 ppm at the completion of 10 min flotation; while at the same time Ag, Fe and S recoveries reached 91.3%, 32.0%, and 95.8%, respectively.