Valuable precious metals such as gold and palladium are used for surface treatment in electroplating processes in the printed circuit board industry. In these processes, there is no need to rinse the plated printed circuit board after the actual active bath. This results in large amounts of "contaminated" wastewater with the electroplating substances gold and palladium in it. Due to the lack of efficient recovery technologies, these wastewater is currently unused discarded. As a result, the critical raw materials Gold and Palladium are irretrievably lost with the waste water.
The recovery of these valuable materials requires efficient systems for the concentration of liquid substances. Currently used conventional separation techniques for concentrating (removal of water) are thermal evaporation, or pressure-driven membrane separation process. These conventional separation processes usually have a relatively high thermal and / or electric power consumption.
The membrane distillation (MD) is an energy efficient alternative with a lower thermal and electrical energy consumption at a low temperature level. The thermal energy required for the MD could easily be provided by carbon-neutral heat from other production processes the printed circuit board production or from other renewable energy sources as solar thermal.
The aim of the project MD-Gold is to develop an energy-efficient and sustainable process for the recovery of the valuable raw materials gold and palladium from processes of the printed circuit board production. This should be done through the adaptation and development of the membrane distillation (MD) process to the chemical, physical and process-technical characteristics of the surface treatment processes.
The result of the project will be an optimized membrane distillation plant on a laboratory scale with precise knowledge of process parameters such as flow rate, temperatures, power consumption, etc.. Furthermore, an optimized and characterized membrane module will be developed and the suitable operating parameters will be determined as well as a technical and economic concept for a scale-up, which allows a monetary evaluation of the technology, will be developed.