So you just cant plug in a different mill into the plant....

So you just cant plug in a different mill into the plant. Downstream from the mill is fine or close to it as the mill has a steady output and would not need much modification, however; upstream is going to need some money spent on it. You cant just tip buckets of ore in. You need to feed a steady stream of ore into the hammer mill. So from the porthole to the ROM and then the mill feed needs ore hoopers and conveyors. That needs money. Pedro cant just shovel quick enough...