What happens to body parts like bones that don't turn to ashes during a cremation?

Is it true that bones remain in tact even after a cremation and if so are said bones ground down or what do the crematoriums do with them.  more

All organic bone fragments, which are very brittle, as well as non-consumed metal items are "swept" into the back of the the cremation chamber and into a stainless steel cooling pan. All non-consumed items, like metal from clothing, hip joints, and bridge work, are separated from the cremated remains. This separation is accomplished through visual inspection as well as using a strong magnet for smaller and minute metallic objects. Items such as dental gold and silver are non-recoverable and are commingled in with the cremated remains. Remaining bone fragments are then processed in a machine to a consistent size and placed into a temporary or permanent urn, selected by the family.  more