Let me point you to two good papers on the flotation of mixed copper oxide and sulphide minerals with xanthate and hydroxamate collectors.

A great detailed thesis called “An Investigation of Copper Recovery from a Sulphide-Oxide Ore with a Mixed Collector System” and one called “Flotation of mixed copper oxide and sulphide minerals with xanthate and hydroxamate collectors” are both must read for the topic of oxide copper flotation.

A new player in the small specialty sphere of hydroxamate collectors and complex mineral processing is oxide collector by Oxflo.

Its product is still somewhat “unknown” but presents interesting and what I consider superior technical characteristics and advantages over its competitors like AM2 (AKA Rinkalore) mentioned in the 2nd article above.