This thesis deals with research activities performed on-site in Peggau and at outside companies. The current processing plant is divided into a raw material processing and a washing plant. Predominantly investigations were performed at the washing plant in order to evaluate its performance and to prepare suggestions for an optimised plant operation. Based on preliminary laboratory examinations, test series with different raw material qualities and variations of process parameters, e.g. throughput rate and specific water consumption, were made. The performance of the washing plant was assessed in terms of the fines remaining in the final size fractions. It was shown that the performance depends significantly on the residence time of the raw material in water to soak and disperse the adherent clay film. The results and findings lead to four different process flow sheets with special regard to implementation of existing equipment and their evaluation in terms of performance, through-put, energy and water consumption.