An Investigation of Flowability and Compaction of Iron Ore Fines

Iron ore is an important material for iron and steel making. About half of mined iron ores are fines which can cause many problems in handling and processing of iron ore. It is therefore important to understand the flow properties of iron ore fines and to increase their sizes. The flowability of iron ore fines is measured by the shear testing method. The yield locus line is drawn based on the measured shear stress and compression stress. The unconfined yield stress, cohesion and flow function are then obtained from the yield locus line using the Mohr circle method. Different types of iron ore fines are tested in the experiments. Compared with the goethite fines, the magnetite fines have higher cohesion, larger unconfined yield stress and flow function. The compaction behaviour of different types of iron ore fines is conducted using a Universal Testing Machine, focusing on the effects of load pressure, particle size, particle mixture and moisture contents. It is found that larger loads and particle size increase the compact density. Also particles mixtures with different size ranges leads to higher relative density. The unconfined compression is used to measure the compressive or crushing strengths of compacts. It is observed that crushing strength of magnetite and goethite powders reach the highest strength with 5% moisture content and with 2.5% moisture content for hematite. Moreover, particle mixtures for magnetite and goethite powder also result in higher crushing strength. The diametrical compaction is used to measure the tensile strengths of compacts. Under the same experiment condition, a compact has much lower tensile strength than compressive strength. The consolidation pressure and particle size have similar effects on the tensile strength to those observed for the compressive strength. The findings from the work will help us develop better understanding of the powders and lead to better design and control of the handling of iron ore fines