It won't work like that as it comes down to chemical consumption...

It won't work like that as it comes down to chemical consumption rates given metallurgy & flow sheet of an operation. Just because the mine producers more tonne, doesn't mean it needs more chemicals. ILU and mineral sands often have more clays, slimes that you don't see in copper or base metal operations. I suspect ILU will be consuming a lot more chemicals per tonne than La Bambas thus doubt that a long term commercial contract for La Bambas would generate revenue on a volume scale like you suggest. It'll most likely be less than $4m.