Quantitative sorting using dual energy X-raytransmission imaging

Dual energy techniques are well-known methods in Xray
transmission imaging. However they are not commonly used
in a quantitative manner in sorting applications. We introduce a
method called Basis Material Decomposition (BMD) that allows
the determination of the fraction of mass of different, a priori
known materials using two X-ray spectra and/or spectral detector
efficiencies for dual energy X-ray imaging. The method exploits
the dependency of the X-ray attenuation on density and
atomic number of the object and the energy of the X-rays. One
example is the quantitative sorting of pollutants from valuable
material, e.g. halogens as bromine from plastics to enhance their
recovery rate significantly. A possible application in mining is
the detection and sorting of diamonds from the host ore kimberlite,
allowing diamonds to be detected even if they are covered in
mud or dust or completely enclosed in the ore. We present measurements
from a lab setup and discuss how this approach can
provide benefits in an industrial environment in the near future.