Transcript MMSL Technical Workshop 2008

MMSL Technical Workshop – March 25 – 26, 2010
Managing Heat Exposure in
Canada’s Underground Mines
Steve Hardcastle
RC 140 – Underground Mine Environment
Presentation Outline
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Acknowledgements
Introduction
Impact
Research Objectives
Research Methodology
Results
Interpretation and Discussion
Other Work
Conclusion/Recommendations
Next Steps
Acknowledgements
• Deep Mining Research Consortium (Agnico-Eagle,
Barrick
Gold, Xstrata, Goldcorp, Vale Inco, Rio Tinto, Industry Canada, Ontario’s
Northern Development and Mines, City of Greater Sudbury)
• University of Ottawa (Drs Glen Kenny & Frank Reardon, Research
Associates and test subjects)
• Agnico Eagle, Vale Inco, Xstrata Nickel, FNX
Mining (Provision of test sites and subjects)
• Mines and Aggregates Safety and Health
Association’s Ontario Mine Rescue Program
• WSIB, NSERC, University of Ottawa Research
Chair, Canada Foundation for Innovation (Parallel
funding)
• Kevin Butler, Charles Kocsis, Gary Li (MMSL Staff)
Introduction
• The research is comprised of a suite of projects
performed by the University of Ottawa and
CANMET-MMSL in co-operation with the mining
industry and safety agencies.
• The issue, with a changing surface climate,
greater depth and continued mechanization using
larger equipment, Canadian underground mine
workers have an increasing risk to be exposed to
heat stress
• This is not only a health and safety issue for the
worker but also a productivity and cost issue for
the mining company.
• Reducing exposure time limits productivity and
changing the thermal environment is expensive
Impact
Program Activity Architecture (PAA)
1.1.1 Innov. &
Prod. – 20%
2.2.1 Strong Env. Perf. – 30%
3.1.1 Mining Safety – 50%
• Mining safety may seem to be the driving factor
but how heat is managed affects productivity and
a mine’s environmental impact
• To combat heat you either need more air or
chilled air both can be multi-$M investments and
consume significant power that produce GHGs.
• Reducing productive face time affects profitability.
Improved guidelines and methods to determine
ventilation volumes and refrigeration can
increase productivity and help competitiveness.
Research Objectives
• Due to the cost and safety issues, industry,
workers and regulatory agencies need a better
understanding of what are the causal factors
contributing to heat stress in mines and how they
can be managed
• Analyze mining activity and conditions
• Simulate under controlled laboratory conditions
(current & future – adverse)
• Explore clothing, age, fitness, work practices
• Evaluate current management practices and
exposure monitoring
• Develop more appropriate guidelines and
mitigating strategies
Research Methodology
Four aspects of the
physiological research
Laboratory Task
Simulation
Mine Rescue
Assessment
Clothing
Work : Recovery
Exposure Management
Protocols
Research - Task Analysis
• Equipment – Physiological Testing
Skin / Core
Temperatures
O2 / Energy
Consumption
Heat Production
/ Storage
Research - Task Analysis
• Experimental procedures - Example
Miner Work
Simulation
• The Movements (Tasks)
T#1: Sitting
T#2: Treadmill (legs)
T#3: Pulleys (arms) T#4= T#2 + T#3
• Schedule - Occupation 1 (Bolting)
T#2 (4 min), T#1 (3 min), T#4 (9 min),
T#2 (1 min), T#4 (48 min), T#1 (1 min),
T#4 (2 min), T#1 (16 min), T#4 (29 min),
T#2 (7 min).
• Similar schedules for 3 other
occupational groups
• Simulations under “normal” and
“adverse” environmental conditions
Results – Adverse Conditions
Subjects unable to complete test
Rectal Temperature (ºC)
38.5
Environment
39ºC 60RH
Core
Limit
35ºC 80RH
35ºC 60RH
35ºC 40RH
38.0
30ºC 60RH
37.5
Work
1: 386 W
2: 360 W
37.0
3: 345 W
4: 227 W
36.5
1
0
2
3
20
40
4
60
Time (min)
5
80
100
6
120
5: 365 W
6: 285 W
Research – Upper Limit
• Extreme Task – Mine Rescue
10 Subjects
Age (yrs) 25 - 62
Height (m)
Weight, Semi-nude (kg)
Body Fat (%)
Equipment (kg)
Average
47
1.78
87.4
19.7
21.9
SD
9
0.07
12.1
3.9
1.7
Research - Upper Work Limit
• Rescue Team 4 + 1 Simulated Exercise
Repeated 5 times
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Loads: 25-155 kg
Incline: 0-20%
Distance: 0-250 m
Temperature:
< 20C
• Work: 400-750W
• 5 Ramp & 2 Level
Elements
• Duration 65 mins
Results – Rescuers already at risk
38.2
680
38.0
600
Continuous increase
520
37.8
No recovery
at lighter
work rates
37.4
440
360
37.2
280
37.0
200
36.8
120
0
10
20
30
40
Elapsed Time (min)
50
60
70
2
37.6
Energy (W/m )
Average Core Temperature (ºC)
• 5 Tests x 2 Subjects
• 3 subjects
>38C within
20 – 50 min.
• Environment
very cool
compared to
a deep mine
• Clothing
limits
evaporation
of sweat /
promotes
heat storage
Research – Clothing Properties
• Evaluating the human/clothing system
Wicking
Undergarment
Coveralls
Full PPE
Work Pant
Wicking T-Shirt
Research – Clothing Phase 1
Initial Tests performed under abstract conditions
to isolate benefits of specific clothing
ensembles
• Test in hot and dry to maximize evaporation
potential
• Limit air velocity to avoid discomfort during
the recovery period.
• Choose “heavy” work rate: cycling @ 400 W,
to generate a high heat load/greatest cooling
potential across clothing
• 5 clothing ensembles including semi-nude
control
• 8 subjects tested under each condition
• 60-minutes of work, 60-minutes of recovery
Results - Clothing
• Change in core temperature
Esophageal Temperature (ºC)
1.0
Control - Shorts
Undergarment only
Mine gear only
Mine gear + undergarment
37.66ºC
0.8
0.6
0.4
0.2
37.25ºC
Exercise
Recovery
0.0
0
-0.2
15
30
45
60
Time (min)
75
90
105
120
• Less heat loss
with coveralls
causes core
temperature to
continually rise
• Sportswear
similar to being
naked
• Coveralls store
more heat when
resting
• Note length of
recovery decay
and residual heat
Research – Heat Storage/Recovery
Other research has shown heat to be cumulatively
stored with each repeated work session.
Tests performed in University of Ottawa’s
calorimeter
• Same level of exercise (360W) used throughout
• 4 trials of 8 subjects, random order
• The environmental temperature is increased
through Trials 1 to 4, from 28 to 31.5C wet-bulb
• Work duration and recovery adjusted as
temperature increased, from 100% work, through
75:25, 50:50 and 25:75 work/recovery regimes
• Subjects wore work-pants, wicking t-shirt and full
mine PPE
Results – Protocol Increasingly
over-protective
Trial 1
Rectal Temperature (°C)
38.2
Trial 2
Trial 3
Trial 4
38.0
37.8
37.6
37.4
37.2
37.0
0
15
30
45
60
Time (min)
75
90
105
120
• 120 mins of
continuous work
completed without
exceeding 38C
• Final core
temperature
decrease through
trials
• Recovery period
more than
compensates for
the higher
environmental
temperature
Interpretation and Discussion
• Results shown are snap-shots
• The body of data needs to be
assessed en masse
• Other issues/avenues of
research
Age/Fitness
Wind speed
Hydration
Increased air density at depth
Optimum recovery time
Improved work:rest protocols
Other Work – CANMET Roles
• CANMET-MMSL are not only
responsible for managing & advising
in the heat stress research.
• It has had specific responsibilities to
evaluate the suitability of instruments
used to assess the thermal environment
– these are what the industry will use to
determine acceptability
• It has also helped identify why it can become hot
underground and how it could be addressed – it
may be a very simple ventilation solution
• It has also been tasked with the University of
Ottawa to produce a non-medical handbook
Conclusions/Recommendations
• This research has benefited from the use of
the University of Ottawa’s calorimeter.
• Nobody else has, or has had, a similar Gold
Standard facility to truly investigate heat
stress.
• This research thrust has generated a
significant amount of useful data during the
last 5 years.
• The industry’s present interest is now to
communicate this science and to develop
better heat management strategies.
• This work could also help modify the current
regulations to something more scientifically
based.
Next Steps
• Complete current testing schedule
• Communicate the science to the client
• CIM presentations, Ventilation Symposium
Workshop
• Continue with Peer reviewed publications,
these are needed to facilitate any change in
regulations or to adopt something different
• Support the harmonization of regulations
and delivering a common scientifically
founded message through the available
guidelines
• Seeking funding/support for the additional
issues
Questions?