I don't think we will ever get the ability to toss out the inert materials. But I can see them giving us a filter to toss out materials that are below a specific threshold and not have rocks being uniform upon their crackin. This gives the concept of veins of minerals in the base rock and while you can take the richer rocks and toss the lower grade rocks. Gives a purpose for a refinery and the advantage the Orion has over the Prospector.
Maybe not all the inert materials, but at least a solid portion. If you are cracking something with a 20% material content, the system should be able to at least filter out the junk with a very low content,
They talked about the rock saying 20% copper. You crack the rock into 8 pieces 2 of those pieces will have a content of copper at 40%, two have a content of copper at 15% and one has a content of 1%. It was then discussed that the Prospector might break down the two harvested pieces at 40% into even smaller bits and that is were the filter would filter out rock that doesn't meet a player selected threshold only keeping the small rocks that have a ore content above say 40%. But it will never be like the Orions refinery which is able to extract all of the ore and eject all of the inert material.
But even the Orion's refinery was brought up as having a max throughput so the tractor beam operators would still want to only drag in rocks that had a higher percent targeted ore instead of trying to process everything. I can see the density of the asteroid field and the sell price of the minerals being a deciding factor in what base level you would run through the refinery.