A non-invasive technique for sorting of alumina-rich iron ores

This paper describes an Infrared (IR) thermography based technique for sorting of iron ores consisting of
alumina-rich particles of relatively low thermal absorptivity as compared to iron-rich particles in the
ores. The technique primarily consists of selection of iron ores with Fe compositions ranging from 59
to 69 wt.% and alumina (Al 2 O 3 ) from 0.35 to 8.85 wt.%, crushing the ores up to the particle size range
around 10 mm. The iron ore fines are uniformly heated using heat source of wavelength ranging from
10 2
to 10 6
m for a period of time sufficient to create a difference in infrared emission between the
ore particles. The thermal image of the heated ores is captured by IR thermography. The alumina-rich iron
ore particles are heated up less as the thermal absorptivity of these ores is less than the ores with high
iron content. Thus, the alumina-rich iron ore particles can be identified by observing the temperature
profile and/or thermal image of these ores. This technique of ore recognition can be useful in improving
the feed quality of iron ore to the blast furnace in iron and steel industries by rejecting the alumina-rich
ores through modification in the presently existing processes.