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Fibrous minerals and dust – managing the risksPart 1 Dust and mineral fibre exposure
Please read this before using presentation
This presentation is based on content presented at the Exploration Safety Roadshow held in December 2010
It is made available for non-commercial use (e.g. toolbox meetings) subject to the condition that the PowerPoint file is not altered without permission from Resources Safety
Supporting resources, such as brochures and posters, are available from Resources Safety
For resources, information or clarification, please contact:
or visit
www.dmp.wa.gov.au/ResourcesSafety
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Why mineral fibres?
Rising demand for State’s minerals so some previously uneconomic orebodies containing fibrous minerals are now commercially viable
Increased probability of encountering fibrous minerals as depths of exploration and mining increase
All airborne fibrous minerals have some health implications
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Recent release
Guideline - Management of fibrous minerals in Western Australian mining operations
Help mining industry understand hazardsRisk-based approachFibrous minerals management plan
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Mineral fibre types
Asbestos “Asbestiform minerals”
Erionite
Winchite
Brucite
Rickterite
Pyrolusite
Many others
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Asbestiform and non-asbestiform minerals
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Asbestiform riebeckite Non-asbestiform riebeckite
Types of asbestos
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Asbestiform fibre types
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Crocidolite(Amphibole)
Chrysotile(Serpentine)
Origins of asbestos
Parent rock is mafic or ultramafic (igneous)
Disturbance in rock formation (e.g. faulting, slippage)
Heat, pressure, water and minerals from parent rock lead to asbestos crystal formation
Often occurs in “lenses” or bands (mm – cm)
Mineral deposits with asbestos present include iron ore, nickel sulphides
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Asbestos minerals probability
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Pros and cons of asbestos
Useful properties Fibrous morphology
Durable
High tensile strength, flexible
Heat and corrosion resistant
Low electrical conductivity
Detrimental aspects Health implications from inhalation of airborne fibres
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Why are mineral fibres hazardous?
Airborne and respirable size (low micron)
Morphology (long and thin)
Persistence in the lung (insolubility of fibres and macrophages)
Interaction of fibres with lung tissue to induce free radical formation
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Respiratory system – particle size
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Alveolar region of lung
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Health effects
Asbestosis
Lung cancer
Mesothelioma
Plural plaques
Type of asbestos inhaled is important factor in determining which lung disease may develop
crocidolite (blue) > amosite (brown) > other amphiboles >> chrysotile (white)
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Exposure to asbestos fibre
Typical non-occupational exposure is 0.0001 fibres/mL
National exposure standard (TWA) is 0.1 fibres/mL (any form of asbestos)
Humans breathe 10 to 20 m3 of air per day
10 m3 of air = 1,000 respirable fibres breathed per day
About 25,000,000 fibres inhaled in a lifetime
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Exposure measurement
NOHSC:3003 (2005) Membrane Filter MethodMSIR 9.13 1b (iv) and 9.33 (2)
Light microscopy
Electron microscopy (SEM, TEM)
Direct reading instruments
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Respirable fibre definition
Widely used definition
< 3 µm diameter
> 5 µm long
> 3:1 aspect ratio
Mining definition in WA [MSIR 9.33 (3)]
Maximum width 1 µm
Length > 5 µm
> 5:1 aspect ratio
Fibre = morphology (not mineralogy)
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Controls
Control dust = control fibre emission20
RC dry drilling RC wet drilling
