Case Studies in Spectroscopy
Integrated Spectronics, an innovative Australian company,
has developed one of the world's most sophisticated infrared
field-portable spectrometers, the Portable Infrared Mineral Analyser
(PIMA). The PIMA is the size of a shoe box and works within seconds,
making it easy for geologists in remote locations to measure the infrared
reflectance spectra of individual rocks.
To help geologists interpret PIMA spectra, especially
mixtures, CSIRO scientists have developed The Spectral Assistant (TSA), a
sophisticated software tool that assists in identifying the constituent
minerals of a rock sample.
TSA Version 4 is at the heart of another CSIRO package,
The Spectral
Geologist, which is marketed commercially and has been sold to mineral
exploration companies throughout the world.
Using a database of about 500 samples representing natural
variation in 42 pure minerals, TSA uses modern and fast multivariate
statistical techniques to find the most likely pure minerals and the most
likely mixtures of two minerals. Figure 1 illustrates its use.
TSA Version 5 is currently under development, following
the completion of an AMIRA-funded project "Automated
Mineralogical Logging of Drill Core, Chips and Powders". It will
be applicable to spectrometers other than the PIMA, such as the ASD,
which also measure visible spectra.
Figure 1 shows the logarithms of 5 reflectance spectra.
Four of these are from the database: two kaolinite (red samples) and two
muscovite (blue samples). The green line shows a known mixture of kaolinite and
muscovite. TSA correctly classifies this
test sample as such a mixture using diagnostic features in the pure spectra, in this case
those present at around 1400 and 2200 nanometres.
Knowing the composition of bauxite ore helps to determine
whether it can be processed profitably. CSIRO has worked with Alcoa of
Australia Limted to help evaluate methods of constructing multivariate
calibration models, relating Fourier transform infrared spectra of bauxite
ore to the concentrations of its constituents. CSIRO scientists evaluated
different baseline correction methods along with non-linear models. This
helped show that a constituent concentration, combined with a partial
least squares model, yielded near-optimal results over a broad range of
concentrations. This method is now in use in an automated ore analysis
system at Aloa's Kwinana mining laboratory.
CSIRO Mathematics, Informatics and Statistics is
collaborating with CSIRO Plant Industry to develop near infrared (NIR)
monitoring protocols for a variety of food products. For whole-wheat
grains, it allows protein content to be assessed on arrival at the silo.
In preparation of wheat-flour dough, NIR can be used to track free and
bonded water during mixing.
Experiments to assess the quality and potential of Prime
Hard wheat require a cheap and efficient way of assessing dough
properties. NIR spectroscopy is quicker and cheaper than direct laboratory
measurements of quality indicators. CSIRO statisticians used a partial
least squares method to develop predictions of dough properties from NIR
spectra of grain samples.
There are many more industrial applications of
spectroscopy. CSIRO can help you find the right spectroscopic solution to
your analytical needs.
For further information contact:
Mark
Berman
Tel: (02) 9325 3205
Fax: (02) 9325 3200
Email: Mark.Berman@csiro.au
Locked Bag 17
North Ryde NSW 1670
Aloke
Phatak
Tel: (08) 9333 6184
Fax: 9333 6121
Email: Aloke.Phatak@csiro.au
Private Bag No 5
Wembley WA 6913 |
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