Oxidation of nickel concentrates in simulated reaction shaft conditions of the flash smelter

• The ignition and combustion of nickel concentrates were investigated using a laminar flow furnace. • The effects of temperature and oxygen enrichment in the process gas were determined. • The ignition of the nickel concentrates started at a temperature below 800 °C. • The highest sulfur removal from nickel concentrates was achieved under the most oxidizing conditions. • Fe and S were preferentially oxidized forming SO 2 and a porous FeO x -rich rim. The suspension oxidation of nickel sulfide concentrates in flash smelting conditions was studied using a laboratory-scale laminar flow furnace. The effects of temperature (800–1100 °C) and oxygen concentration (40–85 vol%) in the process gas were investigated. The surface morphology and mineralogical compositions of samples were examined using scanning electron microscopy equipped with energy-dispersive X-ray spectrometry. The sulfur removal from concentrates was determined using chemical analysis assuming iron as a non-volatile component. It was found that ignition of the nickel concentrates started at a temperature below 800 °C. The sulfur removal from the sieved concentrates increased with increasing temperature. The oxidation was initiated with preferential oxidation of iron in sulfides forming an iron oxide-rich scale on sulfidic core.