The impurity management in flash smelters has become more and more challenging and important in recent years. HSC Sim modelling tool was used to quantify arsenic flows in various processing steps under different scenarios in the flash smelting process. The model covered the processing chain from copper concentrates to copper anodes, and the gas line part included the waste heat boiler and the electrostatic precipitator. The effects of arsenic concentration in the feed, matte grade, and dust circulation are discussed based on the modelling results. Temperature has a significant influence on impurity behaviour as the impurities evaporate and condense in different parts of the process depending on the temperature. To better understand the behaviour of volatile impurities, such as arsenic, lead and antimony, laboratory-scale experiments were conducted under controlled conditions with a newly developed experimental equipment setup using arsenic as a model impurity. The intention is to expand the methodology to other impurities after the link between laboratory experiments and industrial behaviour is established.