That is a tough one, there is not much you can do about oxide minerals in a sulfide float.  You can try some sulfidizers like NaHS that might help the oxides be more floatable, perhaps some copper sulfate but you run the risk of floating more iron.  Sorry I dont have a lot of good advice for you, if the minerals are fully oxidized you are a bit stuck with this type of performance.  If it is just oxidized coatings perhaps changing the grind a bit might help as well, if possible.

Regards

The first solution is always to evaluate the effect of Na2S. Sometimes, there are good results. The mineralogy plays an important role. You can add Na2S in the rougher or scavenger circuit. You should know that the air promotes the degradation of Na2S, for that reason its efficiency is in the first cells.

Other possible solution is to add PAX and Cytec Promoter 6494, which is an hydroxamate. The addition of 6494 depends on the content of copper oxide ore. The pH should not be more than 10. The addition of soda ash could be useful to regulate the pH.

If you don't have a cleaner-scavenger circuit, try to include it. This circuit can reduce part of copper lost in the cleaner tails. Other point to review is your retention time in the rougher and scavenger circuits. This kind of ore may need more flotation time.

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