Q4. A sampling study is conducted to all streams of a plant treating copper ore for performance evaluation study. Copper minerals are mainly chalcopyrite but also includes some secondary Cu minerals such as covelline and chalcocite as well. According to mineralogical analysis, a graph is given below defining the recovery (dilution) of sphalerite in Cu concentrate. Mark the following comments correctly describing the graph and possible solution for improvement. (36 pts)

1. Sphalerite is recovered to Cu concentrate mostly as free particles (T) (F)
2. Sphalerite is recovered to Cu concentrate as it is locked with copper minerals in coarse sizes (T) (F)
3. Sphalerite recovery to Cu concentrate is definitely by entrainment (T) (F)
4. The reason of sphalerite recovery in Cu concentrate may be the activation of secondary Cu minerals (T) (F)
5. The reason of sphalerite recovery in Cu concentrate may be the inadvertent passivation (T) (F)
6. Sphalerite is recovered to Cu concentrate as it may not be depressed properly (T) (F)
7. As the sphalerite is mostly recovered to Cu concentrate by entrainment, mass pull should be reduced (T) (F)
8. Dilution of sphalerite in Cu concentrate can be prevented by using proper reagents (T) (F)
9. CuSO₄ is the best chemical for improving this dilution (T) (F)
10. Regrinding may help the locking with Cu minerals (T) (F)
11. The dosage of the collectors can be increased for better recovery of sphalerite to concentrate (T) (F)
12. The dosage of ZnSO₄ can be optimized for depression of sphalerite (T) (F)