Colorado Goldfields Inc. (fka CGFI)

[M_T_Pockets]

I'm not sure contemplating your navel lint will solve much, RKY! Believe me, I have tried.

I'm pretty certain, (but I still am assuming,) that the aggregate from each mill is kept separate. I would also assume that just like any other contract type processing, small amounts would need to carry a premium charge. You would have to clean out the mill to get that customer's precious metal out before moving on to the next batch. That clean out takes time and labor.
From what I see, contracts are usually for so many thousand tons or cubic yards of material, with minimums required. That way the mill can plan their work schedule accordingly.
I would also think that the aggregate would be delivered on a "just in time" schedule for the planned processing days. That way there would be less of a chance for mixing product from different sources.
Storage can become a problem if you try and hold too much material, but you do want to have enough to make a "run" without any down time.

This is basic "production" or "plant management" philosophy. It usually applies to most processing type operations. The only other factor I see is the frequency of required clean outs per production period.
Richer material would require more clean outs to eliminate loss of ore. (The capture ripples can get filled and the metals can be washed past the capture devices. So, there is a optimum point a clean out is required.)
That should also be predictable by the assay of the material to be processed. (The richer the aggregate, the more often you need to collect the separated metals. That is a good thing!)

I wish I could find a formula for this. So far I haven't found anything specific. I suspect it varies from mill to mill. With the formula, I would be able to better predict the most efficient minimum lot size the POW mill could accept. However, the actual figures probably are still a bit nebulous, since the mill has not run in the last few years.
The last production manager probably has these figures in his head and could tell you down to the quarter hour how long it should take to process any size lot.
You know how these things are, RKY, you get a good feel for these things with experience. There is "plans" and there is "reality". I good project / plant manager has "reality" down to an artful science.