Crematorium

“Cremation doesn’t require embalming of the body or a casket. When a body is cremated the chamber is heated to over 1500 (up to 2000) degrees Fahrenheit. The body is placed in the retort, which is a special chamber lined with bricks that help retain the heat. Cremation may actually take up to four hours, as the furnaces are designed to facilitate the maximum disintegration of the corpse. These furnaces run on natural gas or propane.
There are special control systems that monitor the cremation process. Pollution controls have been added to recent models and some states and provinces have provisions concerning emissions during the cremation process. This means that cremation is now even more environmentally friendly.
After the cremation is completed, crematory staff will carefully remove all the remains that can be recovered. Any metal particles are also extracted. There will likely be some fragments of human bones. Some crematories will pulverize these into ashes”