The starting point for the development of a novel process for simultaneous washing and separation of fine particles was the task of removing accompanying impurities from a crystallized plant extract and separating the crystals in a purified form. For this purpose, an innovative technical concept was developed, fundamental aspects were investigated on a laboratory scale, and the process was successfully carried out on a pilot scale in a joint project. In principle, the new method is based on a static sedimentation apparatus with integrated countercurrent washing, which operates continuously and produces a purified solid concentrate.