sulphide versus oxide

BT and others....

Am trying to get a clearer picture of Plant and Process.

First: Flotation.

AVB has oxide and sulphide deposits. There have been some negative remarks about the oxide, like it was a poor country cousin. Lots of it at AS and very shallow too.

1. AVB Flotation is targetted at sulphides (Chalcopyrite). Grind up, put in bubble tanks (spa baths sort of, but not for people) skim off froth as concentrate, and scavenge gold from sediment at bottom. Yield say 97% of the original copper metal in concentrate. But what about good old oxide?

(ref: Flotation of Mixed copper oxide and xanthate minerals with xanthate and hydroxamate collectors... . pdf)

"Sherwood Copper’s Minto Mine processes a high grade copper–gold deposit in Yukon, Canada. The ore mined is from a primary copper sulphide deposit with separate additional deposits of copper oxides.
In conjunction with Ausmelt Chemicals, Minto is currently investigating options to recover copper oxide and sulphide minerals using flotation by blending their primary sulphide ore with oxide ores. The blend used in this laboratory scale investigation was 70% sulphide ore and 30% oxide ore on a weight basis. The copper sulphides present in the blend were bornite and chalcopyrite, while the oxides were malachite and minor azurite.From previous flotation investigations of mixed copper oxide and sulphide minerals using xanthate and hydroxamate collectors it was hard to distinguish the impact of the alkyl hydroxamate collector on sulphide recovery as the sulphide and oxide minerals occurred naturally together. In the case of the Minto operation the copper oxide and sulphide minerals occur in separate ore deposits and can be treated separately
or blended together. This investigation has shown that using n-octyl hydroxamates (AM28 made by Ausmelt Limited) in conjunction with traditional sulphide collectors can successfully simultaneously recover copper sulphides and oxides by flotation from blended ore minerals. The copper sulphide recovery did not decrease when processing the blended ore compared to treating the sulphide ore independently.
At a blend of 70% sulphide ore and 30% oxide ore, the rougher scavenger copper recovery was as high as 95.5%. The copper recovery from the blended ore using a mixture of collectors was shown to be superior to the recovery obtained using only xanthate after controlled potential sulphidisation."

So now we hear that one can indeed happily flotate(?) a 70/30 blend of sulphide and oxide, if you know what you are doing. In fact your yield is 95.5% which is only down slightly on what we get with the pure sulphide of 97%.

(I think that says you get to keep 97% of the original copper when you concentrate the ore)

Just cruise on down to your local Ausmelt store in downtown Parauapebas and pick up some n-octyl hydroxamates, and away you go. Easy.

This suggests to me that if you go dig out the DSO at AS and then expose the oxide and/or sulphide this provides a ready feed stock for the plant at the start, when it is built. To get you going.

A puzzle : Malachite (oxide) has 57% copper. Chalcopyrite Cu.FeS2 has 34% Cu.

So pound for pound the oxide contains more copper. As above it can be recovered successfully through flotation. It would seem like the best target to me? If not, why not??

.. over to others perhaps who have some in-depth knowledge on this subject.... to clarify the waters.