This is a blower similar to the one I have, except mine has a pully and drive belt to turn fan, instead of direct drive as pictured.
By removing the fan part (looks like a big hamster wheel) from the shaft and installing paddles or string of some kind to the shaft . . . hey, success could be just around the corner!
Of course I would also have to install some kind of mesh or wire grate over the blower end to sift the smaller pieces through. Also, a piece of sheet metal to block one side of blower where motor connects.
Next would be to install wheels, making it portable. This would be a heavy-duty machine. Those are my thoughts for now.
Any info would be appreciated.