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| CSIRO | SOLVE | Issue 11 | MAY 07 | |
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ARTICLE
PARTICLE ANALYSIS:
Laser Bounce Gives Ice-cream the Lick By Heather Catchpole
Minerals processing technology is helping a diverse range of companies, from ice-cream producers to those in the environmental sector.A laser diffraction technique used to examine crushed ores is finding a new, diversified role in food manufacturing. The technique, which uses the angle at which laser light is diffracted from particles to determine their size distribution as a volume percentage, forms part of the Particle Analysis Service (PAS), a business offshoot of CSIRO Minerals.
In an expansion of CSIRO Minerals’ traditional mining clients, an ice-cream maker, the Peters and Brownes Group, has used PAS’s lasers to determine ice-cream quality by measuring the size distribution of butterfat emulsion droplets, a key component in getting the creamy texture of ice-cream just right. PAS has widened the uses for its technology from the analysis of mining materials to many other applications, including environmental problems such as wind-blown dust containment and optimising waste-water treatment. Although the Perth-based facility still performs analysis of drill core and other samples for mining companies, up to half of the company’s clients now come from the environment sector, as well as its incursions into food. Even chocolate has come under the scrutiny of the particle analysis system. The size of particles of cocoa fat influences the taste of chocolate – large particles make chocolate bitter, while producing particles that are too small can be inefficient because energy is wasted. Another foodstuff checked out by the facility is cat biscuits. The size of the flour particles in the biscuits needs to be consistent to suit the equipment used to churn out cat chow. Typical environmental jobs undertaken at PAS include checking sediment sizes in soil and mud samples, and nuisance dusts, says laboratory manager Rick Hughes. The size distribution of particles can determine, for example, the extent to which dredging at river mouths will create plumes of fine silt that will take a long time to settle, or whether particles at a land rehabilitation site will be picked up as wind-blown dust. “Forty to 50 per cent of our services are now done for clients in the environmental sector,” Mr Hughes says. Vic Semeniuk from V&C Semeniuk Research Group has used PAS and other technologies at the facility for researching soils, minerals and biological components. He says the facility is fundamental to the company’s research. The facility examines the physical characteristics of anything containing particles, and can measure the distribution of particle size, the number of particles present, and the volume, surface area, density, porosity or surface charge of individual particles. Laser diffraction is one of the service’s most frequently used techniques. Another method, ‘light extinction’, counts the number and size of particles in a sample solution. A finely focused laser beam detects each individual particle as it passes the laser. The particles block, or extinguish, the light as they pass. This allows researchers to pinpoint with great accuracy how systems involving particles work in nature, such as the seemingly esoteric question of how many individual grains of pollen are carried away by a bee after a single visit to a flower (useful for orchardists interested in bee pollination). Altering the equipment to deal with difficult samples and transporting it to remote locations have allowed the small team to take on some unusual jobs.
On one occasion the PAS team had to undertake two days of underwater helicopter-escape training to work offshore on North West Shelf oil rigs. The laser diffraction instrument sampled the size and concentration of oil droplets in water liberated from the rock formation with the crude oil. This information helped the company determine the most efficient way of separating the oil before the water was pumped back down into the formation. “The oil droplets we were looking at coalesced and changed from a fine emulsion to a thin film on top of the water within a very short time period,” Mr Hughes says. “The samples needed to be analysed within minutes of collection.” For further information contact: |
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