- Photo 1: Gold and silver are typical metals which can be thermal recovered
Material recovery is a source of income for an incinerator. The recovered materials are mostly in the ash of the combustion chamber, or in the flue gas. The evaporation temperature and the melting temperature of the component is defining if it stays in the ash or it will travel with the flue gas to the filters and the ash hoppers.
Melting temperature and evaporation temperature
Metals (exept Hg), have mostly a high melting temperature. Where the material travels, to ash bin or to the flue gas treatment depends from his characteristics. For example:
For aluminum (Al), this will travel to the ash chamber, because Al has a melting temperature of about 600 degr.C, and a evaporation temperature of about 2500 degr.C. So it doesn't evaporate, it melts mostly and stays in the bottom ash. It is now an art to take out of the ash all the different materials by mechanical, chemical and other separation processes.
The most simple way of separation of the materials from the ash is mechanical. Fe (iron) is magnetic, so it will be easy to lift it out by a magnetic belt.