Compressor and 90 lb hammer, get a fracture line started and work a face, similar to blasting rock in a quarry. Hoe hammer on an excavator,or possibly a rubber tire hoe should make short work of this, be careful of rebar and tires, hopefully the thick area is just a skirt around it, if not, the hoe hammer on an excavator would make it an easy job, you want to fracture not punch holes through it, machine does the work.
Couple of years ago, I demo'd a pool with a new D4G Cat, the walkway surrouning the pool was concrete. The walls of the pool were also partly concrete, and strengthened by metal panels. This dozer having a 6 way blade on it, required some care and took quite a few tries to find a weak area in the walkway, it just would not budge, I cleared a deep layer of top soil from around it on all sides first, and ramped up to the edge of it, eventually I saw some movement and finally got one piece out, that weakened it, and I was finally able to place all the pieces in the hole.
With that size tractor, it should push it out, but it sounds like the slab has a good bite into the subgrade still. You would need to dig down low around it, and get a push on it that kind of faces upward, gaining some leverage, hopefully you have a straight blade 7S type and not the 7A angle blade, both are very strong with outside push arms. When you start pushing on something like this without using the center of the blade and or a cushion of dirt you can damage it, more so the 7A type, being wider, and still being very stout blade, there are some serious forces at work, just have know when enough is enough.
I pulled the pin&bushing end of a tilt cylinder out of a D6D straight blade when grading off blasted rock spoils, whil'st using a blade corner to get one rock up and moved, mind you the pin bushing was worn and thin, track pads worn out too, but it still put some substantial force to the blade and peeled the end off it like it was nothing, it just failed, easy fix, not as strong as I thought it was though.
Not sure what the size of this pad is but it being a grain bin it must not have a large footprint, I'd fire up that D7 and start pushing and cutting low all around it if you can, just undermine all around it, you will then have much better leverage having the tractor lower even ramp up to an edge of it if you have a cable blade, if that is the case you will have to use some care to not break the cable, a stronger multi part line set up would be best, mine is only 4 part, have to watch the cable with something like this, keeping tension off it as much as possible using the ground as a guide, also have another set of eyes close by to watch for the smallest movement of the slab, once it is seen moving it tells you whether you are gaining an edge or not, use a cushion of dirt to protect the bowl of the blade, you might still get it out, if no go, once fractured it will definitely come out.
