Cold compressive strength of iron ore pellets in distinct reduction stages

The worldwide use of blast furnaces (BF) in ironmaking continues. The generation of fine matter in the BF shaft hampers the furnace operation and causes particle emissions. The tendency of the main charge of the BFs, iron ore pellets, to produce fines during the process is evaluated by means of standardized tests performed at a low constant temperature. In this work, the durability of commercial acid pellets was evaluated by performing cold compressive strength tests on samples that had been exposed to high-temperature experiments aiming for different reduction degrees in a laboratory-scale furnace simulating actual BF conditions. Strength was found to have decreased to a minimum of approximately 59 % of the original result when the reduction degree was 19 %. The studied pellet achieved a comparatively good result in the standardized low-temperature reduction-disintegration test, which shows the uncertainty of current methods in the evaluation of ferrous burden materials. [Display omitted] •Cold compressive strength of iron ore pellets varies in blast furnace conditions.•Strength of pellets drops immediately in hematite-magnetite reduction phase.•An average decrease of 59 % in pellet strength was observed.•The larger the particle size, the weaker the reduced pellet is.•Unstandardized tests provide interesting data on ferrous burden materials.