The thermal reduction process (burning) of the Chemicals Division at Heraeus Precious Metals in Hanau is equipped with three chamber furnaces as the central assembly. Spent catalysts containing precious metal and based on coal carriers, or for example residues from the homogeneous or other carbon-containing materials must be thermally reduced right at the outset of the recycling process in chamber furnaces.
The actual burning process takes place in the combustion chamber of the furnace, which is indirectly heated. The material (recycling and customer material) is placed in stainless steel trays and stowed on racks for the actual thermal reduction process in the furnace.
The flue gases generated during the burning process, such as acidic gases, nitrogen oxides and dioxins, are cleaned with a complex and state of the art process. This process consists of an afterburner, scrubber, and an exhaust gas catalyst. Finally a precious metal-rich ash is yielded, which can be easily homogenized by milling and then be sampled. This sample is crucial for the determination of the precious metal content.