A laboratory fluid bed roaster was used to study the rate of roasting by analysis of the off gas. The roasted calcine formed a NiO phase saturated with 30% tenorite (CuO) in solid solution. The mineralogy of the second copper oxide phase was found to depend on the amount of excess air used during roasting. Cuprite (Cu2O) is more stable at a pO2 of 0.05 atm., while tenorite is formed at 0.21 atm.Fluid bed roasting of Bessemer matte containing copper, nickel and sulphur was demonstrated at temperatures from 900°C to 1050°C. At higher temperatures, the solidus of the copper-nickel oxide calcine is reached and fluid bed roasting becomes impossible due to rapid agglomeration caused by liquid phase sintering. Kinetics are slow below 900°C.Complete roasting of Bessemer matte in a fluid bed is environmentally advantageous since the sulphur dioxide can be economically converted to sulphuric acid. The exothermic roasting reaction provides sufficient energy to achieve the reactor temperatures so no excess fuel is required and no greenhouse generating gases are produced.Non-isothermal thermo-gravimetric experiments were conducted to determine initiation of roasting and reaction kinetics. Isothermal techniques were not possible without melting the sulphide phase, however, batch fluid bed roaster tests closely simulated isothermal conditions by rapidly heating the sulphides particles to target temperature. The kinetics of roasting increases with increasing temperature and with increasing pO2.