Transcript Fibrous minerals and dust

Fibrous minerals and dust – managing the risks
Part 1 Dust and mineral fibre exposure
Please read this before using presentation
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This presentation is based on content presented at the Exploration Safety Roadshow
held in December 2010
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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
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Supporting resources, such as brochures and posters, are available from Resources
Safety
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For resources, information or clarification, please contact:
[email protected]
or visit
www.dmp.wa.gov.au/ResourcesSafety
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Why mineral fibres?
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Rising demand for State’s minerals so some previously
uneconomic orebodies containing fibrous minerals are now
commercially viable
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Increased probability of encountering fibrous minerals as
depths of exploration and mining increase
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All airborne fibrous minerals have some health implications
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Recent release
Guideline - Management of fibrous minerals in
Western Australian mining operations
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Help mining industry understand hazards
Risk-based approach
Fibrous minerals management plan
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Mineral fibre types
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Asbestos “Asbestiform minerals”
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Erionite
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Winchite
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Brucite
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Rickterite
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Pyrolusite
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Many others
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Asbestiform and
non-asbestiform minerals
Asbestiform riebeckite
Non-asbestiform riebeckite
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Types of asbestos
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Asbestiform fibre types
Crocidolite
(Amphibole)
Chrysotile
(Serpentine)
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Origins of asbestos
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Parent rock is mafic or ultramafic (igneous)
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Disturbance in rock formation (e.g. faulting, slippage)
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Heat, pressure, water and minerals from parent rock
lead to asbestos crystal formation
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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
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Fibrous morphology
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Durable
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High tensile strength, flexible
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Heat and corrosion resistant
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Low electrical conductivity
Detrimental aspects
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Health implications from inhalation of airborne fibres
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Why are mineral fibres hazardous?
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Airborne and respirable size (low micron)
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Morphology (long and thin)
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Persistence in the lung (insolubility of fibres and
macrophages)
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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
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Asbestosis
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Lung cancer
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Mesothelioma
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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
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Typical non-occupational exposure is 0.0001 fibres/mL
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National exposure standard (TWA) is 0.1 fibres/mL
(any form of asbestos)
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Humans breathe 10 to 20 m3 of air per day
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10 m3 of air = 1,000 respirable fibres breathed per day
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About 25,000,000 fibres inhaled in a lifetime
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Exposure measurement
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NOHSC:3003 (2005) Membrane Filter Method
MSIR 9.13 1b (iv) and 9.33 (2)
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Light microscopy
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Electron microscopy (SEM, TEM)
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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
RC dry drilling
RC wet drilling
Control dust = control fibre emission
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Any questions?
For further information please contact:
Dave Fleming
 [email protected]
 9358 8551
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