X-ray imaging could detect individual minerals in ores

An X-ray imaging detector could be used by the mining industry to quickly and accurately detect which minerals are present in an ore sample.

The postage-stamp-sized device, developed by researchers at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia, uses photon-counting to create high-resolution images of minerals.

Although X-rays have long been used to image mineral ores, with shades of grey depicting the density of different components, these images do not easily identify the individual minerals present.

With the device, an X-ray tube fires beams through grains of ore and a sensor on the other side measures how X-rays of different energies are attenuated by the objects in the beam. For example, gold changes the spectrum of transmitted X-rays differently to nickel or molybdenum.

The device then images the grains of the ore in detail, producing pictures in which colours correspond to the elements contained in the sample.

‘So far this has been done mostly using scanning electron microscopes,’ said CSIRO’s Dr Josef Uher. ’You take the ore sample, put it in resin, make a cylinder that contains the ore particles inside, cut the cylinder in half, polish the surface and then look at that surface with an electron microscope. It takes hours.’

The device could provide near real-time imaging of ores for plant monitoring and control in the mining industry. It was designed in collaboration with several universities and laboratories led by the European Organisation of Nuclear Research (CERN).

CSIRO researchers are also looking at using laser-induced breakdown spectroscopy (LIBS) to accelerate the subsequent in situ analysis of ore quality at mine sites.