This master thesis investigates the separation of complex sulphide minerals present in a fluorite-barite ore. The industrial sample analyzed in this work contains significant amounts of copper and silver-bearing phases. These phases are enriched into a valuable concentrate by flotation, with the long-term objective of maximizing the recovery of the valuable components through process optimization. Grinding tests are first conducted at a laboratory scale using a wet-operated rod mill. Critical flotation feed characteristics and comminution indexes are determined from the grinding products such as particle size distributions and specific energy consumption. Lab-scale flotation tests are thus conducted to evaluate the effects of feed particle size, conditioning parameters, collector types and dosages, and the number of flotation stages. Particle size class-specific analyses in the form of Henry-Reinhardt diagrams for the flotation tailings are finally conducted to refine the process parameters and to gain knowledge about its limits.