A study to develop a fault diagnosis system in the pneumatic injection of copper concentrate into a Teniente Converter at Caletones Smelter, Chile, is presented. The availability of the injection system must be improved at least in 2% to satisfy the actual production demands, The most frequent operating failures were pump pressurisation and pump overcharge. However, most of the problems were due to disturbances propagation either from the reactor or silo operation. A preliminary diagnosis of the whole system was made in terms of identifying the main constraints to develop and implement a supervisory system. This system must coordinate the local control loops, avoid the main operating problems and provide guidance to operators to handle specific situations, in order to increase the availability of the injection system and to improve the concentrate tonnage control. (C) 2002 Elsevier Science Ltd. All rights reserved.