Experience with reprocessing mixed copper tailings

[cal west]

I've been looking into the potential of reprocessing old copper tailings that are a mix of both sulfide and oxide material. Read up already and it can be tricky since each type usually calls for a different recovery process, and blending them together complicates things even more
Has anyone here worked on projects dealing with mixed type copper tailings? I'm always interested in hearing about practical challenges and what sort of recovery rates people have managed in the real world

 

[south sandwich]

We had the same problem on a site in Arizona a while back. The tailings had both chalcopyrite and malachite, and it made things tough. We ended up splitting the mix. We used acid to treat the oxide part and sent the sulfide stuff through flotation. It was more work, but we got about 60-65% recovery. Mixing everything at the start caused issues, so if you can sort it early, it really helps.

 

[harew0od]

We had the same problem on a site in Arizona a while back. The tailings had both chalcopyrite and malachite, and it made things tough. We ended up splitting the mix. We used acid to treat the oxide part and sent the sulfide stuff through flotation. It was more work, but we got about 60-65% recovery. Mixing everything at the start caused issues, so if you can sort it early, it really helps.

I ran into a similar mix at a small copper site in Nevada last year, but we didn't split it and recovery was rough. When you treated the malachite with acid, did you go with sulfuric or something else?

 

[Shelley_Goodwin]

From what I found, a good approach is to pretreat the oxide portion (activation, sulfide conversion) and then run flotation circuits tailored for sulfides. One paper suggested using collectors like KM series plus sodium sulfide to “activate” copper oxides so they float more like sulfides. You’ll probably need a circuit that’s flexible (you might bypass or split flows for oxide vs sulfide zones).