Post on 17-Dec-2015
PHYSIOLOGICAL RESPONSES OF UNDERGROUND COAL MINERS UNDER INIMICAL WORKING ENVIRONMENT
Delivered By ~
Dr. Netai Chandra DeyPROFESSOR(MINING)
BENGAL ENGINEERING AND SCIENCE UNIVERSITY, SHIBPUR, HOWRAH
Reasons to take up Ergo based research work
Objectives of the study
Unit operations in UG mine
Provision of ergonomic study in DGMS circular
Selection of subject for the study
Physical characteristics of Roof Bolters
Threshold limit values of different environmental parameters
An overview on physiological status w.r.t some strain indices
Time element of roof bolting activity in spell and shift
Determination of work load as per various scientific classification
Adequacy of job duration in mines
Possible R & D initiatives
Conclusion and recommendations
Lecture Content
WHY ERGONOMICS-BASED RESEARCH WORK IN MINING IS IMPORTANT?
Huge base of workers constituting more than 80% of total
work force in mining industry.
Huge absenteeism about 30-35%.
Significant report of sufferings from MSD’s and postural
problems, which indicates poor health of miners.
Considerable compensation is being paid to the miner by
private and public enterprises.
Poor OMS of underground miners which is around 0.5-0.6
since last 10-15 years, indicates poor efficiency of UG
miners.
Mine reserve sustainability in India for at least next 100
years
OBJECTIVES OF THIS PARTICULAR STUDYOBJECTIVES OF THIS PARTICULAR STUDY
Determination of workload of selective category of miners
Optimization of job duration of different mining operation with respect to given environmental inputs.
Determination of workload of selective category of miners
Optimization of job duration of different mining operation with respect to given environmental inputs.
Executive: 15,431Supervisor: 36,855Workmen: 3,28,359 (86%)
Total: 3,80,645
MANPOWER OF CILMANPOWER OF CIL
Open cast
Under ground
MANPOWER OF SCCLMANPOWER OF SCCL
Executive: 2477Supervisor: 14,568Workmen: 49,041 (74.3%)
Total: 66,086
As per DGMS Circular & Xth conference on safety in mines held in
New Delhi during 26-27 Nov.2007 following ergonomic study have
been made mandatory:
1.Assessment of work processes
2.Assessment of posture
3.Assessment of tools/aids
4.Cardio- vascular assessment
5.Vibration studies of machines as per ISO
As per DGMS Circular & Xth conference on safety in mines held in
New Delhi during 26-27 Nov.2007 following ergonomic study have
been made mandatory:
1.Assessment of work processes
2.Assessment of posture
3.Assessment of tools/aids
4.Cardio- vascular assessment
5.Vibration studies of machines as per ISO
PROVISION OF ERGONOMIC STUDY IN DGMS CIRCULAR
How ergonomics can help industryHow ergonomics can help industry
Work load determination and adequacy of workload to an Individual.
Work optimization can be done through changing environmental
parameters.
Work station designing.
Designing of HEMM’s and other machine operator’s seating, cabin etc.
Handling of heavy tools.
Postural study to minimize musculo-skeletal disorder(MSD) related
troubles.
Work load determination and adequacy of workload to an Individual.
Work optimization can be done through changing environmental
parameters.
Work station designing.
Designing of HEMM’s and other machine operator’s seating, cabin etc.
Handling of heavy tools.
Postural study to minimize musculo-skeletal disorder(MSD) related
troubles.
Priority based criteria that have been used to select the different mining operations for the present study are as follows:Priority based criteria that have been used to select the different mining operations for the present study are as follows:
1. Activities that are quantitative in nature.
2. Activities where the miners have to devote a significant time at a stretch in the allocated working area.
3. Activities that are supposed to be relatively physically demanding under adverse conditions of mines.
1. Activities that are quantitative in nature.
2. Activities where the miners have to devote a significant time at a stretch in the allocated working area.
3. Activities that are supposed to be relatively physically demanding under adverse conditions of mines.
Category BMI range (kg/m²)
Severly underweight <16.5
Underweight 16.5-18.5
Normal 18.5-25
Over weight 25-30
Obese classes >30
Stages of human BSA values (Acceptable
limits)For men 1.9 m²
For women 1.6 m²
REFERENCE:1. Adapted from US EPA 19852. WHO recommended body weight based BMI values for
adults.
PHYSIOLOGICAL PARAMETERS (DIRECT & DERIVED) IN ROOF BOLTING FOR TWO DIFFERENT MINE
PARAMETER Mine A (n=5) Mine B (n=5)
WHR(bpm) 123.8±3.77(120-130)) 109.8±3.77(105-115)
RCC (%) 54.08±4.80(48.11-61.45) 52.18±4.75(47.11-60.45)
NCC(bpm.) 53.2±3.34(51-59) 28.2±3.34(22-30)
OT(0F) 99.2+0.4(98.4-99.8) 99.3+0.4(98.6-100.2)
It is observed that roof bolters experience the highest responses in both spells except
net cardiac cost.
Mean WHR for both group gets elevated around 70-75% compared to their resting
responses. Both the elevation is statistically significant.
PERCENTAGE OF ROOF BOLTING WORK EXCEEDING THE RECOMMENDED LIMITS OF PHYSICAL STRAIN
INDICES ACCEPTED LIMITS Mine A Mine B
WHR(bpm) 110 100 60
LCW 35 beats over resting pulse 100 100
RCC (%) 30% 100 80
NCC(bpm) 30 100 60
The average work load of individual roof bolter of two different mine during their bolting activity is judged against various recommended indices of cardiac strain.
It is seen that in mine A 100% of bolters remain above 30% level of RCC whereas 80% of mine B remains above 30% RCC.
WHR of mine A is 100% beyond the limit whereas in mine B it is 60%. The same effect is observed in case of NCC.
Parameter Reference
Classification of workload
Light Moderate HeavyVery
heavy
Extremely
heavy
Roof
Bolting
Driller
(n=5)
Remarks
Working
Heart rate
(bpm)
Astrand <90 90-110 111-130 131-150 151-170 *123.8Roof Bolters are in
heavy category.
Energy
expenditure
(Kcal)
Ramanathan
,et al1.0-2.5 2.6-4.0 4.1-6.0 6.1-8.0 >8 *4.15
Roof Bolters are in
heavy category.
Net cardiac
cost (bpm)
Chamoux, et
al≤20 20-30 31-40 41-50 51-60 *53.2
Roof Bolters are in
very heavy
category.
Physiological workload classification & comparison with observed values(Mine-A)
* Mean values are given
Parameter Reference
Classification of workload
Light Moderate HeavyVery
heavy
Extremely
heavy
Roof
Bolting
Driller
(n=5)
Remarks
Working
Heart rate
(bpm)
Astrand <90 90-110 111-130 131-150 151-170 *109.8Roof Bolters are in
moderate category.
Energy
expenditure
(Kcal)
Ramanathan
,et al1.0-2.5 2.6-4.0 4.1-6.0 6.1-8.0 >8 *3.75
Roof Bolters are in
moderate category.
Net cardiac
cost (bpm)
Chamoux, et
al≤20 20-30 31-40 41-50 51-60 *28.2
Roof Bolters are in
moderate category.
Physiological work load classification comparison with observed values(Mine B)
* Mean values are given
A comparison of cardiac indices & energy expenditure of Roof BoltersA comparison of cardiac indices & energy expenditure of Roof Bolters
Mean±SDRoof Bolter (n=5)
P1 P2 P3
(Range)112.6±5.74
(98-118)98.8±5.24
(90-104)90.6±5.17
(82-97)
Recovery heart rate pattern of Subjects (Mine A)Recovery heart rate pattern of Subjects (Mine A)
Mean ±SDRoof Bolter (n=5)
P1 P2 P3
(Range)
99.2±6.83 (95-106)
87.6±5.50 (82-98)
82±5.41 (78-86)
Recovery heart rate pattern of Subjects (Mine B)Recovery heart rate pattern of Subjects (Mine B)
Brouha’s fatigue assessment techniquesBrouha’s fatigue assessment techniques
Condition Criteria
Normal state P1 - P3 ≥ 10 bpm and P1, P2, P3 ≤ 90
bpm
No – recovery state P1 - P3 < 10 bpm and P3 > 90 bpm
Inverse recovery state P3 > 90 bpm and P1 - P3 ≤ -10 bpm
No increasing cardiac strain P1 ≤ 110 bpm and P1 - P3 > 10 bpm
BOLTER (Mine A) TIME(MIN) NUMBER
work duration per shift 101.12±2.43(99.4-102.84) -
spells per shift - 4
spell duration per shift 25±0.06(25-26.99)* -
% time spent by different job elements in an activity of a spell
walking with machine & accessories - 5.61
Considering 5 effective hours in a
shift
roof checking - 5.98
drilling in roof - 21.52
Soaking , pushing of cement cartridge and insertion of bolt - 12.6
Tightening of bolt nut - 2.5
BOLTER (Mine B) TIME(MIN) NUMBER
work duration per shift 63.8±2.6(61.4-65.3) -
spells per shift - 3
spell duration per shift 21±0.12(20.2-23.4)* -
% time spent by different job elements in an activity of a spell
walking with machine & accessories - 3.2
Considering 5 effective hours in a
shift
roof checking - 4.34
drilling in roof - 12.4
Soaking , pushing of cement cartridge and insertion of bolt - 6.8
Tightening of bolt nut - 1.6
UNDERGROUND MINE ENVIRONMENT PARAMETERS (Mine A)
PARAMETERS DB(°c) WB(°c) NWB(°c)AIR VELOCITY
(m/min)
WBGT(°c) HUMIDITY (%) ET(°c)
MEAN±SD (RANGE)
28.84±0.72(28-30.5)
27.74±0.68(27-29.5)
28.23±0.71(27-30)
4.92±4.65(1-18)
28.41±0.69(27.3-30.3)
92.07±1.68(89-98)
29±0.35(28-29.5)
Classification of environmental zone at various level of ET
Classification ET(0C) Observed value(0C)
Very hot zone >30
29*Hot zone 28.33-29.94
Warm zone 26.67-28.28
Comfortable zone 21.11-26.61
*Values are given °C, ET & WBGT
Permissible Heat Exposure Threshold Limit Values: - (By ACGIH)
Work Rest Regimen Light Moderate HeavyContinuous work 30.0 26.7 25.075% of work; 25% of rest, each Hr. 30.6 28.0 25.950% of work; 50% of rest, each Hr. 31.4 29.4 27.925% of work; 75% of rest, each Hr. 32.2 31.1 30.0
Observed WBGT values
28.41*
UNDERGROUND MINE ENVIRONMENT PARAMETERS (Mine B)
PARAMETERS DB(°c) WB(°c) NWB(°c)
AIR VELOCITY
(m/min)
WBGT(°c) HUMIDITY (%) ET(°c)
MEAN±SD (RANGE)
31.5± 0.96 (28.5-33.5)
29.9±0.94(26.5-31.5)
29±1.02(27-32)
22.2 ± 0.12(12.6-42.6)
27.8 ± 1.06 (26.5 -31.5)
88 ±3.5(75-93)
27.95 ±0.35
(26.5-31.5)
Classification ET(0C) Observed Value(0C)
Very hot zone >30
27.95*Hot zone 28.33-29.94
Warm zone 26.67-28.28
Comfortable zone 21.11-26.61
Classification of environmental zone at various level of ET
Permissible Heat Exposure Threshold Limit Values: - (By ACGIH)
Work Rest Regimen Light Moderate HeavyContinuous work 30.0 26.7 25.075% of work; 25% of rest, each Hr. 30.6 28.0 25.950% of work; 50% of rest, each Hr. 31.4 29.4 27.925% of work; 75% of rest, each Hr. 32.2 31.1 30.0
*Values are given °C, ET & WBGT
Observed WBGT values
27.8*
Category of work
Actual work (in
each hour) Mine A
Recommended work (in each hour) Mine
A
Actual work (in each hour)
Mine B
Recommended work (in each hour)
Mine B
Roof Bolter 20.22Min.* 15 Min. 12.76 Min. 45 Min.
* Effective time in a shift is considered to be 5 hrs.
In Mine A the roof bolters are doing more work (though this may not be adequate)
than the recommended work limit. Hostile Environment is responsible.
In Mine B the roof bolters are doing much less work than the recommended work limit.
The hostile environment of Mine A is responsible for increased job demand and hence
the bolters are in heavy work load category. So, the mine unit is deprived of effective
utilization of system inputs whereas, the humanizing environment of Mine B helps to
reduce the job demand to moderate category.
The roof bolters of mine B are heavily under loaded and the jobs should be increased
accordingly.
The environment of Mine A should be monitored and improved adequately so that
their work limits can be enhanced appropriately.
In Mine A the roof bolters are doing more work (though this may not be adequate)
than the recommended work limit. Hostile Environment is responsible.
In Mine B the roof bolters are doing much less work than the recommended work limit.
The hostile environment of Mine A is responsible for increased job demand and hence
the bolters are in heavy work load category. So, the mine unit is deprived of effective
utilization of system inputs whereas, the humanizing environment of Mine B helps to
reduce the job demand to moderate category.
The roof bolters of mine B are heavily under loaded and the jobs should be increased
accordingly.
The environment of Mine A should be monitored and improved adequately so that
their work limits can be enhanced appropriately.
Job duration optimization of Roof Bolters in MinesJob duration optimization of Roof Bolters in Mines
Possible R&D initiatives required in mining field
Workstation designing in under ground and open cast.
Ergonomical designing of HEMM’s operators cabin
Postural study regarding operators reach/ control with respect to
HEMM’s
Determination of workload and adequate work rest regimen for
miners in different working conditions and work environment.
Nutritional study
Delay in onset of fatigueness to maximize worker’s efficiency in
mines
CONCLUSION & RECOMMENDATIONS CONCLUSION & RECOMMENDATIONS
Decreases Injury Frequency so that the compensation made towards
the employee is drastically reduced.
Increases production and productivity
Ergonomic study helps to scheduling and optimizing the work bouts to
reach the companies objective comfortably.
Decreases Absenteeism.
Increases Health and Comfort which will have direct impact on the
work efficiency of employee.
Decreases Injury Frequency so that the compensation made towards
the employee is drastically reduced.
Increases production and productivity
Ergonomic study helps to scheduling and optimizing the work bouts to
reach the companies objective comfortably.
Decreases Absenteeism.
Increases Health and Comfort which will have direct impact on the
work efficiency of employee.