Steve HardcastleRC 140 – Underground Mine Environment

Managing Heat Exposure in Canada’s Underground Mines

MMSL Technical Workshop – March 25 – 26, 2010

Presentation Outline

• 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

2.2.1 Strong Env. Perf. – 30% 3.1.1 Mining Safety – 50%1.1.1 Innov. & Prod. – 20%

Program Activity Architecture (PAA)

Impact

• 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 MethodologyFour aspects of the

physiological researchLaboratory Task

SimulationMine Rescue

AssessmentClothingWork : Recovery

Exposure Management Protocols

Research - Task Analysis• Equipment – Physiological Testing

Skin / Core Temperatures

Heat Production/ Storage

O2 / Energy Consumption

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

36.5

37.0

37.5

38.0

38.5

0 20 40 60 80 100 120

Time (min)

Rec

tal

Tem

per

atu

re (

ºC)

30ºC 60RH

35ºC 60RH

39ºC 60RH

35ºC 40RH

35ºC 80RH

4 5 1 2 3 6

Subjects unable to complete test

1: 386 W

2: 360 W

3: 345 W

4: 227 W

5: 365 W

Environment

6: 285 W

Work

CoreLimit

Research – Upper Limit• Extreme Task – Mine Rescue

10 Subjects Average SDAge (yrs) 25 - 62Height (m) 1.78 0.07Weight, Semi-nude (kg) 87.4 12.1Body Fat (%) 19.7 3.9Equipment (kg) 21.9 1.7

47 9

Research - Upper Work Limit• Rescue Team 4 + 1 Simulated Exercise

Repeated 5 times

• Loads: 25-155 kg• Incline: 0-20%• Distance: 0-250 m• Temperature:

< 20C• Work: 400-750W• 5 Ramp & 2 Level

Elements• Duration 65 mins

Results – Rescuers already at risk

36.8

37.0

37.2

37.4

37.6

37.8

38.0

38.2

0 10 20 30 40 50 60 70

Elapsed Time (min)

Av

era

ge

Co

re T

em

pe

ratu

re

(ºC

)

120

200

280

360

440

520

600

680

En

erg

y (

W/m

2)

• 3 subjects >38C within 20 – 50 min.

• Environment very cool compared to a deep mine

• Clothing limits evaporation of sweat / promotes heat storage

• 5 Tests x 2 Subjects

Continuous increase

No recovery at lighter

work rates

Research – Clothing Properties• Evaluating the human/clothing system

WickingUndergarment

Work PantWicking T-Shirt

CoverallsFull PPE

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

Research – Clothing Phase 1

Results - Clothing

Time (min)

Eso

ph

agea

l T

emp

erat

ure

(ºC

)

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

0 15 30 45 60 75 90 105 120

Exercise Recovery

Control - Shorts

Mine gear onlyUndergarment only

Mine gear + undergarment

37.66ºC

37.25ºC

• Change in core temperature • 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/RecoveryOther 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 31.5C 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

37.0

37.2

37.4

37.6

37.8

38.0

38.2

0 15 30 45 60 75 90 105 120

Time (min)

Rec

tal

Tem

per

atu

re (

°C)

Trial 1 Trial 2 Trial 3 Trial 4

Results – Protocol Increasingly over-protective

• 120 mins of continuous work completed without exceeding 38C

• 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

researchAge/FitnessWind speedHydrationIncreased air density at depthOptimum recovery timeImproved 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 instrumentsused 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?