Process challenges and recent developments in magnetite beneficiation technologies
The aim of this paper is to discuss selected challenges associated with wet processing of magnetite iron ores and present recent technological advances aimed at mitigating these challenges. For decades the steel industry has depended on iron ore concentrate sourced from hematite ores. However, the high demand for steel products over the years resulted in iron ore commodity price increase which led to the development of other magnetite deposits. Presently, Australia is the largest exporter of iron ore in the world with more than 90% of these exports coming from Pilbara regions of Western Australia. There are huge magnetite deposits located within South Australia (estimated over 12 billion tonnes) that require strategic measures to upgrade them to achieve their full economic potential. A typical magnetite processing flowsheet involves comminution, wet magnetic separation and flotation, regrinding and further magnetic separation. Magnetite mineral is generally fine grained and requires fine to ultrafine grinding (P80 <45 mum) to achieve sufficient liberation for effective beneficiation processes. The challenges associated with wet processing of magnetite ores include huge comminution energy requirements, processing water acquisition and disposal, especially in arid regions and slime production. The recently developed IMPTEC superfine crushers (SFC) and Cyclomag planar magnetic separators (PMS) which provide dry processing approach for magnetite beneficiation, present an alternative process flowsheet to mitigate the sustainability and economic risks associated with heavily water dependent magnetite processing. This paper reviews selected challenges associated with wet processing of magnetite iron ores and discusses the potential of the application of the IMPTEC SFC and Cyclomag PMS as unit operations in dry beneficiation of magnetite iron ores with respect to comminution energy, process water acquisition, process effluent disposal and environmental footprint.