Microanalysis, CSI style and helping to rewrite standards
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Forensic Analysis of Errant and Nuisance Particles

Many of us have been in the situation where we look at our car or our washing and wonder ‘just how did it get covered in that dirt?’ In most cases nuisance particles are just that, ‘a nuisance’, causing time and effort/cost to remove or clean. In some cases these same particles can be quite harmful, in others it can mean a breach of compliance with local, state or federal government regulations which limit or control the emissions that are allowed to be released from a business or process.
So how can you tell what a particle is and where it’s come from?
Microanalysis Australia is routinely tasked to do just that. Metal fabrication plants often grind, weld, sand blast and spray paint as part of their daily manufacturing/repair processes. It may not always be possible to conduct such activities in a controlled (indoor) environment and occasionally a release of errant particulate may be carried on the wind onto neighbouring properties. Depending on the wind conditions, freshly created particles of metal fragments, welding fume or spray paint may drift and settle on buildings, cars, boats etc which, if left unchecked can build up to unsightly levels at best or damage surfaces prematurely and cause ill health at worst.
Scanning electron microscopy (SEM) allows the automated or manual, rapid analysis of between hundreds and thousands of particles and the associated mineralogy and likely origin to be determined.

The particles in the above image were collected from site by using double-sided carbon tape, an SEM-ready acquisition technique that allows particles to be quickly analysed and interpreted. The particles range in size from 5 µm to 80 µm and represent garnet blast media covered in paint and steel fragments from a metal preparation process. Carbonaceous fibres from local flora can also be seen. The relative abundance of the elements can be used to compare against suspect mineral/metal phases and used to positively identify particles by specific origin.
Microanalysis can differentiate sand blasting media – from garnet, olivine, staurolite and other neosilcate minerals, to metal/metal oxides, glass beads and steel media. Tell-tale signs of controlled particle size coupled with high angularity (post blast-induced fracture) and associated pigments such as titania and barite lend weight to the activities being conducted when the blast media was being used. Welding fume has its own size, morphology and chemical fingerprint and is readily distinguished from background environment dust.
Local regolith (local environment geology) often needs to be taken into consideration when highlighting anthropogenic phases.
Airborne dusts from stockpiles or earthworks may travel considerable distance if their size distribution is fine enough. Naturally occurring mineral fibres or components of low toxicity at the point of origin may be concentrated and effectively refined by wind transport meaning that locations downwind may be exposed to a size range and composition that may only represent a trace component of the original material. Air monitoring is useful in abstracting inhalable and respirable size fractions over longer acquisition times to get time weighted averages of dust emissions for both static (positions in a designated environment) and personal (individuals moving around an environment). Microanalysis routinely measures the quantity and composition of particles on filters used to collect both total suspended particulate (TSP) and inhalable (PM10) and respirable (PM4) particles. Morphologies and mineralogies of these particulates are crucial in understanding the risks posed to health as well as general amenity.

Rick Hughes

Standards Australia MN-005 Committee

Kalamunda Senior High School
It was my pleasure last week to attend a meeting of the Standards Australia MN-005/MN-005-03 committee pertaining to Copper, Lead, Zinc and Nickel Ores – Sampling and Chemical Analysis. I am now a member of these committees as endorsed by AXAA, and will be participating in the development and revision of Australian, Australian/New Zealand and International Standards. During the review and creation of these standards, input will be sought from industry, laboratories and other relevant parties.
Look out for our requests for expertise so you can contribute to AS, AS/NZS and ISO standards!

Nimue Pendragon
Welcome Aboard Ian Davies
Ian has worked in the Western Australian scientific field for almost 30 years encompassing research, heavy industrial and commercial environments. Primarily specialising in mineral characterisation using X-Ray Diffraction he is used to complex analytical challenges. Ian has a wide expanse of knowledge across many fields of analysis with some of his favourite areas of interest including, but not limited to, micro-characterisation using scanning electron microscopy, automated mineral analysis using SEM/QEMSCAN, thermal analysis using DSC/DTA-MS and auto-titration particularly focusing on both Bayer and Cyanide plant liquors.
We are very excited to have him join the team. If you are in the area please pop in and say hello!

Image Of The Month

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Image taken by Owen Carpenter
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