3. Experimental method
Twenty samples were prepared, each containing the six
minerals corundum, quartz, anatase, rutile, hematite and magnetite.
All minerals were synthetic and had particle sizes in the range
of approximately 5–150 mm. The mixtures were not intended to
represent realistic samples from any particular minerals process;
rather, they were chosen to cover a cross-section of gangue and
commercially important minerals from the alumina, titanium and
iron-ore industries. A total of 20 g of material in dry powder form
was mixed together for each sample and placed into a plastic
Petri-dish with a diameter of 75mm. Each sample contained
different amounts of each component mineral, with the masses of
the components varying over the ranges shown in Table 1. The
samples were not compacted and had thicknesses between 4 and
6mm depending on the sample composition. Six reference
samples were also prepared, each containing just one of the
minerals of interest.
The diffraction spectrum of each sample was measured using
the EDXRD spectrometer. Transmission (01 angle) spectra were
also measured. Diffraction spectra were collected at an X-ray tube
potential of 120 kV and a beam current of 0.5mA with a
measurement time of 2000 s. The transmission spectra were
collected for 200 s at 120 kV and 0.002mA. Sampling errors were
reduced by rotating the sample during the measurement around
the axis of the X-ray beam to increase the mass of material
measured.