Waste-to-Energy is widely used in Europe for treatment of residual waste. After thermal treatment the waste is converted to electrical energy and two “main” types of residues: bottom ashes and fly ashes. One tonne of residual waste results on average in 25-30% of bottom ash. These bottom ashes can be evaluated as a rich source of metals which do not incinerate during thermal treatment. The metals present in these ashes can be divided into ferrous, and non-ferrous metals like copper, aluminum, zinc. These metals are partially recovered against sometimes poor recovery rates. Besides the opportunities that bottom ash offer it is also still classified as waste due to potential environmental leaching of some species from these bottom ashes. These bottom ashes are currently landfilled or used in civil applications. Improvement of metal recovery and bottom ash quality asks for the development of more advanced bottom ash treatment technologies.
Today the standard way of bottom ash treatment is by using magnetic separators and eddy current separators to recover ferrous and non-ferrous metals respectively. The LIFE PCR project is aiming at improving bottom ash quality by recovering copper and zinc by a combination of washing, physical separation and hydrometallurgical treatment. The following value chain indicates the various steps in upgrading bottom ash.
The title of the project LIFE PCR is an abbreviation of Pure Copper Recovery, because copper is the main product in the heavy-non-ferrous mixture recovered from bottom ash. The main focus of the project is however on the recovery and refining of zinc.