I'm am not a metallurgist, however, an existing plant would need...

I'm am not a metallurgist, however, an existing plant would need to set-up to extract all the commodities, be optimised for the ore type and have the capacity to handle the ore stream without displacing its own ore (unless the premium paid os worth more than processing their own ore). Im not sure of that there would be many plants around that tick those boxes. Also, consideration must be given to the additional cost of paying to treat the ore and the haulage costs.
I think the company would be better placed to build up a resource by drilling, which would justify the capital expenditure for a new mine or build up the resource to flog it off to someone who will.