Managing Dust & Mineral Fibre Risks in Mining Operations

1. Fibrous minerals and dust – managing the risksPart 1 Dust and mineral fibre exposure

2. 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: RSDComms@dmp.wa.gov.au or visit www.dmp.wa.gov.au/ResourcesSafety

4. 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

5. Recent release Guideline - Management of fibrous minerals in Western Australian mining operations • Help mining industry understand hazards • Risk-based approach • Fibrous minerals management plan

6. Mineral fibre types • Asbestos “Asbestiform minerals” • Erionite • Winchite • Brucite • Rickterite • Pyrolusite • Many others

7. Asbestiform and non-asbestiform minerals Asbestiform riebeckite Non-asbestiform riebeckite

8. Types of asbestos

9. Asbestiform fibre types Crocidolite (Amphibole) Chrysotile (Serpentine)

10. 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

11. Asbestos minerals probability

12. 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

13. 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

14. Respiratory system – particle size

15. Alveolar region of lung

16. 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)

17. 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

18. Exposure measurement • NOHSC:3003 (2005) Membrane Filter Method MSIR 9.13 1b (iv) and 9.33 (2) • Light microscopy • Electron microscopy (SEM, TEM) • Direct reading instruments

19. 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)

20. Controls Control dust = control fibre emission RC dry drilling RC wet drilling

21. Any questions? For further information please contact: Dave Fleming  dave.fleming@dmp.wa.gov.au  9358 8551