The schematic diagram by MYG on the 2/9/13 shows what you are...

The schematic diagram by MYG on the 2/9/13 shows what you are talking about cashedup.
It shows a Cu/Au concentrate is produced from remaining gold that has not been recovered through the gravity circuit or remaining Cu that has not been removed through the flotation circuit.

I have been burnt investing in companies with flotation circuits for gold and base metals (PGI BSM ) as what happened with them is recovery of a % of metals from and flotation occurs , but then the concentrate is smeltered or goes through another process (CIL) where a further % is recovered so one ends up with 3/4 of 5/8 of not much.
It quite often looks good on paper or in a pilot plant though.
Guessing having a gravity circuit in front of the flotation circuit seems like a good idea as the small nuggets may not recover too well in CIL circuit.