Controlling Exposure to Dust (Silica) in Gold Mining
Vijay Nundlall – Gold Working Group| Sibanye Gold – Driefontein Operations | 7th October 2015
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2
Typical deep level gold mine layout
Mining and Minerals Life Cycle
Regulatory
Framework
Regulatory Framework in Mining (MHSA)
Mine Health and Safety Act (Act 29 of 1996)
Requirement in the Mine Health and Safety Act (MHSA)
Brief Description
MHSA - Section 2
Employer To Ensure Safety
MHSA - Section 5
Employer To Maintain Healthy and Safe Mine Environment
MHSA - Section 6 (3)
Employer to ensure adequate supply of health and safety equipment
MHSA - Section 7 (1) (e)
Employer to staff mine with due regard to health and safety
MHSA - Section 9
MHSA - Section 10
Codes of practice (e.g. Airborne Pollutants / Noise / Thermal Stress, Falls of Ground, Rail bound and Trackless
equipment, prevention of fires and explosions)
Employer to provide health and safety training
MHSA – Section 11
Employer to conduct Risk Assessment
MHSA - Section 12
Employer to conduct occupational hygiene measurements
MHSA - Section 13
Linkage of occupational Hygiene measurements and medical surveillance
MHSA - Section 14
Record of hazardous work
MHSA - Section 19 (1)
Employees' right to information
MHSA - Section 21
Manufacturer's and supplier's duty for health and safety
MHSA - Section 23
Employees' right to leave dangerous working place
MHSA - Section 52
Duty to assist inspector and answer questions
MHSA - Section 53
Duty to produce documents required by inspector
Risk Management in Mining
Hierarchy of Controls
Employment Statistics (2001 – 2013)
Employment Statistics by Gender (2001 – 2013)
Mine Health and Safety Council Milestones (2003 to 2013)
Occupational Health – Silicosis
Mine Health and Safety Council (MHSC) Milestones
(The MHSC is a tripartite institution created by the Mine Health and Safety Act)
Mine Health and Safety Council Milestones (2003 to 2013)
Occupational Health – Silica Exposure : Industry
Performance
% of exposure measurements below the Silica OEL of 0.1 mg/m3
Updated MHSC Milestones
• MHSC updated its Health and Safety Milestone targets in November 2014
• By 2024 95% of all exposure measurements to be below 0.05mg/m³ for respirable
crystalline silica
• MHSC expect following from industry
• Timely adopt leading practices
• Timely adopt identified research outcome
• Identify programme of work per objective
• Sibanye Gold has operational Noise and Dust document
• Compiled an updated Noise and Dust prevention strategy to complement its
current document
Mine Ventilation Systems
Bulk Air
Cooler
Main Fans
Surface
Winder
Main Vertical
Downcast Shaft
Upcast Shaft
Booster Fans
Walls
Sub Vertical
Downcast Shaft
Doors
Orepass
Raise bore
Vent holes
Stoping lines
Return Airways
Dust filters
Regulator
R
Intake Airways
Shaft skip
loading
Development
Auxiliary Fans
Conveyor belts
Intake air
Used air
Return air
13
Silicosis prevention interventions
• Number of interventions introduced by Sibanye Gold
Footwall treatment
Haulage sprays
Protection at main ore passes
Winch covers
Health rooms
Silver membrane filters
Stope atomising sprays
Re-energised development water
blasts
Effect of Initiatives to reduce dust load, 2008 to date.
(Graph indicates annual average dust load – Not Silica)
INITIATIVES TO REDUCE DUST LOAD
2008 TO DATE (Graph indicating annual average dust load – not Silica)
0.400
Introduction of
silver membrane
filters
0.350
Tip
Filters
Dust Load mg/m³
0.300
0.250
0.276
Footwall
treatment
Haulage
sprays
0.272
0.250
0.282
2013 Winch covers
0.248
0.200
0.203
2013/4 Stope
atomising spray
0.150
0.100
0.113
0.050
0.000
2008
2009
2010
2011
2012
2013
2014
Mining Operation ABC
15
Footwall treatment
• The importance of footwall treatment must not be under estimated
Activity:
Hoppers
station
with
rock
to
Before
Footwall
Treatment
(Aerosols <10μ)
After
Footwall
Treatment
(Aerosols <10μ)
442µg/m³
355µg/m³
Percentage
reduction
19.7
Haulage sprays
• Various spray systems installed across the Sibanye Gold operations
• Risk based installed mostly in intake airways
Protection at main ore pass systems
• Upcasting tips are problematic in some areas.
• Tip covers complementing filtration systems, to further reduce dust exposure
Winch covers
• Winch covers were rolled out across all operations
• Protect winch operators
• Perform compliance checks
Stope atomising sprays
• Effective for wetting complete panels
Watering down
Silver Membrane filters for exposure measurement
• Accuracy of gravimetric sampling process critical
• Switched to silver membrane filters in 2013
• Preferred for X-ray diffraction
• Part of drive to improve accuracy
• No need for acclimatization
Health Rooms
• Health rooms at training centres
• Employee education
Silicosis awareness month
• Silicosis awareness early in 2015
• Four weekly topics
• Three languages
• Discussed at safety meetings
Silicosis month
Silicosis month
Strategy going
forward
Dust (Silica) exposure management
• Need to have systems in place to manage silica dust exposure
• “if we do not measure, we do not know”
• Feedback meetings
• Need to have accurate information on crystalline silica quartz concentration
• Determine required dust load to ensure that dust dose is kept below the OEL
and new milestone of 0.05mg/m³
Strategy going forward
2014 SILICOSIS MILESTONE – 20% ANNUAL IMPROVEMENT
25%
Percentage above Milestone limit (i.e 0.05 mg/m3)
22.5%
20%
18.6%
15.9%
15.0%
15%
12.0%
10.0%
10%
8.0%
6.0%
5.0%
5%
4.0%
3.0%
2.5%
2.0%
0%
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
Planned progressive reduction in exposure to silica
2022
2023
2024
Strategy going forward
• Maintain and comply with current interventions
• Proper watering down regime
• Safe work practices
• Employees to be empowered with knowledge
• Implement additional interventions where applicable
• Subscribe to applicable MOSH leading practices
• RPE to be evaluated on an ongoing basis