Trace element deportment and particle formation behaviour during thermal processing of iron ore: technical reference for risk assessment of iron ore processing

Abstract

Understanding the mechanisms of the formation and emission of pollutants during iron and steel manufacturing is significantly important for improved control, collection, and recycling of the trace element impurities and particle emissions. The aim of this study was to investigate the distribution of trace elements and particle size formation behaviour of products during the thermal processing of iron ores. The effects of gas atmosphere (inert, oxidizing, and reducing) and temperature (850 and 950 °C) on trace element distribution in solid and liquid products were studied in a circulating fluidized bed reactor. The particle size distribution of the solid products was also assessed to determine the proportion of particulate matter formed with a diameter less than 2.5 microns. The study revealed the influence and importance of the gas atmosphere and processing temperature on the particle formation behaviour and deportment of certain trace elements from the input iron ore to the product streams during thermal processing of iron ore. The increase in temperature resulted in further migration of the elements from the iron ore to the particles formed and emitted during the processing. The relative risk assessment from the individual trace elements suggested that manganese and sulphur are the most important elements with highest risk scores in the particles and, in case of sulphur, also in the condensed phase. This paper provides a reference for risk assessment of the trace elements and particle emissions from iron ore processing to facilitate the control, collection, and recycling of trace element impurities and particle emissions.