How to remove stuck Rawl bolts
To remove the part will be tedious, but it may be possible. The bolt that does the securing may be 1/4" or larger? Take a drill bit that is dull for drilling metal that is slightly smaller than the tapped hole in the cone to auger what dust you can. The idea here is to create a small cavity under the cone for water applied through a syringe, the type for applying glue in tight spots, for example, to swirl and loosen the dust under the rest of the cone. That done, after the water runs clear, insert the bolt just enough to engage a few threads and tap the cone down into the flushed out void. Then using a drill bit large enough to drill through the bulk of the sleeve and if needed the cone too, run it into the hole, and drill out what metal you can. You will need a sharp bit for this, but it won't be after you are done possibly. 
With luck, the drill will grab the insert at some time during the drilling and start it to spin in the hole, then with it hung up on the drill from spinning and while it is spinning, withdraw the insert. At worst, drill it all the way out so much it will collapse and fall apart in the hole.