The amount of disposed electrical and electronic equipment has been constantly growing for years. The recycling of WEEE therefore gains more and more importance. The disposed material which originates from processing of coarse components of electrical and electronic scrap, may contain up to 300 grams per ton of precious metals such as gold, platinum and silver. By means of the processing plant of Metran Rohstoffaufbereitungs GmbH a majority of these valuable materials can be recovered. The thesis includes the elaboration of a sampling concept as well as the results of sampling campaigns. The mass streams of the whole plant were balanced, and the separation efficiency of two selected processing apparatus on the base of efficiency curves was elaborated. The special problems of sampling heterogenous waste streams as well as the potential for improvements in plant operation are discussed.