The roasting in air of pellets consisting of copper-iron sulphides and limestone and activated limestone has been investigated to explore the possibility of developing a metal production process that eliminates sulphur dioxide gas emissions. The effects of pellet porosity, sulphide: limestone ratio, pellet sizes and temperature on reaction kinetics were investigated. Thermogravimetry was carried out under air atmosphere. The weight gain of pelletized samples was used to identify and study the phases present in the reaction products. The experimental results indicated that at 500 degreesC using activated limestone, a completely reacted pellet can be produced in about 50 min with very low emissions of sulphur dioxide (more than 95% of sulphur capture). (C) 2003 Elsevier Ltd. All rights reserved.