1

ABSTRACT 

 Stone mines represent the highest percentage of 

operating underground nonmetal mines in the United States. 

With the introduction of stricter Diesel Particular Matter (DPM) 

regulations, large-opening underground room-and-pillar stone 

mine operators are faced with implementing one or more 

alternative methods to reduce concentration levels including: 

install and maintain an effective ventilation system; install 

lower DPM emission diesel engines; the adding of DPM filters. 

The National Institute for Occupational Safety and Health 

(NIOSH) is actively researching various aspects of fan and 

stopping designs in an effort to improve the ventilation of these 

mines. NIOSH has identified and further developed three 

alternative ventilation methods for use in large-opening 

underground mines: split-mine, perimeter, and unit-ventilation. 

This paper describes the implementation of the three methods 

with respect to their use in mines of various levels of 

development. 

INTRODUCTION 

 NIOSH is actively researching ventilation layouts to help 

the underground stone industry meet and surpass Diesel 

Particulate Matter (DPM) regulations to protect the health of 

workers. Large room-and-pillar stone mines in the United 

States represent a major sector of mines in the noncoal mining 

industry. Numerous large room-and-pillar mines began as 

surface quarries, that due to increased stripping ratios or 

environmental considerations, have become underground 

mining operations. These stone mines are characterized by 

massive openings and large expanses that correlate to very 

low ventilation resistances. Historically, natural ventilation has 

been their primary means of diluting airborne contaminates. 

Natural ventilation by itself is no longer regarded as workable 

in large room-and-pillar mines because it does not guarantee a 

consistent measurable airflow (Head, 2001a). Without a 

consistent airflow direction or air coursing, recirculation of 

contaminants will occur, which could result in unhealthy 

working environments. 

Large room-and-pillar stone mining

fundamentals

 The value per ton of ore for large room-and-pillar stone 

mines is typically low, therefore productivity must be high. 

Typical face areas are 12.2 m wide x 7.6 m high (40 ft wide by 

25 ft high) with 4.3 m (14 ft) pulled with each blast (Figure 1). 

This equates to over 1,000 tons of stone per 

development/production blast based on standard ore density. 

Larger face widths up to 18.3 m (60 ft) have been developed. 

An initial development height in thicker beds of roughly 7.6 m 

(25 ft) is controlled by equipment limitations (scalers and roof 

bolters). Benching is common in thicker beds with heights of 

30.5 m (100 ft) having been recorded in mines after 

successive benching. Pillars are commonly set on 30.5 m x 

30.5 m (100 ft × 100 ft) centers with 75% extraction. Roof 

control is typically achieved by leaving strong “roof” rock 

behind where available. Where mechanical rock support is 

required, mines use various types of rock reinforcement 

methods. 

 Mines that have multiple drift (portal) entries with no 

primary restrictions (exhaust shafts, single ramp) can have 

remarkably low ventilation resistances, virtually orders of 

magnitude lower than typical metal and coal mines. For 

example, a 305 m (1,000 ft) long drift that is 12.2 m (40 ft) wide 

by 7.6m (25 ft) high with a k factor of 0.0130 kg/m3

 (70 × 10-10

lb·min2

/ft4) could move 354 m3/s (750,000 cfm) of air at a static 

pressure loss of 25 Pa (0.0984 in w.g.) (Head, 2001b). The 

remainder of the workings, which have an even lower 

resistance in most cases, can be ignored in the calculations. 

Shock losses, air temperature differences, and wind load can 

all have a large impact on ventilation patterns because of the 

low system resistance. The air quantity of 23.6 m3

/s (50,000 

cfm) of airflow moving in a 92.9 m2

 (1,000-ft2) entry is hard to 

measure accurately because most flow-recording devices 

have difficulty reading velocities below 0.25 m/s (50 ft/min). 

Without an effective ventilation system, airflow reversals and 

flow inversions in entries are possible and do occur frequently, 

further complicating accurate airflow measurements. 

VENTILATION METHODS FOR LARGE 

OPENING MINES 

 Three large opening stone mine ventilation methods have 

been previously described by NIOSH researchers: perimeter, 

split-mine, and unit-ventilation (Mucho, 2001) (Grau, 2001b). 

These three methods are main mine ventilation systems 

designed to create stable measurable airflow to the last open 

crosscut by the use of pressurized intakes and returns (Grau, 

2002b). These systems should not be mistaken for auxiliary 

face ventilation of long deadhead drifts or area ventilation that 

could have high recirculation. The following mine layouts have 

been designed mainly for ventilation, but ground control issues 

should also be considered. Standard room-and-pillar mine 

layouts are used, but can easily be adapted for staggered or 

elongated pillars. 

Split-Mine Ventilation 

 Of the three ventilation methods, split-mine ventilation is 

the simplest in terms of layout and design, as the mine is split 

into separate intake and exhaust sides. Split-mine ventilation 

is a mine-wide ventilation method designed to deliver the bulk 

of the main mine fan’s airflow to the last open crosscuts near 

the active working faces. This is accomplished by the use of a 

continuous stopping line that is installed from the portals to the 

active faces. The stopping line is developed parallel to the 

VENTILATION PLANNING LAYOUTS FOR LARGE OPENING MINES 

R.B. Krog, R.H. Grau III, T.P. Mucho, S.B. Robertson 

NIOSH 

Pittsburgh, PA 
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mining direction and trails the active faces by three or four 

breaks, thereby locating the stoppings far enough away from 

the production face shots to reduce damage. Figure 2 shows 

an early split-mine ventilation system. Bulkheads are more 

susceptible to blasting pressure damage than stoppings 

because of their rigid nature and therefore have to be installed 

further away from blasts. Figure 3 shows a propeller fan 

blowing into a new mine that uses the split-mine ventilation 

system. Figures 4 and 5 show how a split-mine is expanded 

over time. As the mine increases in size, around 10 breaks in, 

a large-diameter low-pressure fan can be installed in a 

bulkhead to create a consistent airflow output without 

damaging the bulkhead from blast pressure (Figure 6) 

(NIOSH, 2002a). 

 Figure 1. Typical large-opening mine entry [12.2 m x 8.2 

m (40ft x 27ft)] 

 Figure 2. Split-mine ventilation, (phase 1) fan blowing 

into mine 

 Stopping line considerations: Stoppings near the 

production blasts have to be resistant to high blast pressure 

loading rather than the low static pressure induced by the main 

fans. As development advances away from the stopping, blast 

pressure loading decreases, but a tighter seal is required to 

reduce leakage; thus, the stopping line undergoes different 

loading conditions throughout its lifetime. As the stopping line 

increases in length, the initial permanent stoppings encounter 

a constant static pressure and have to be sealed completely to 

reduce repetitive flapping damage (Figure 7). 

 Figure 3. Propeller fan blowing into a new mine using 

split-mine ventilation 

 Figure 4. Split-mine ventilation, (phase 2) installation of 

first brattice stopping, three open crosscuts 

 The stopping line that separates the two airways could 

be a combination of brattice stoppings, in-place stone 

stoppings or permanent stoppings (NIOSH, 2002b). An inplace stone stopping can be defined as stone left un-mined in 

a room and pillar operation that is used to course airflow by not 

developing the crosscut or entry completely. Figure 5 shows 

five in-place stone stoppings running parallel to the mining 

direction. 

 Air leakage associated with the stoppings can drastically 

reduce the overall effectiveness of a ventilation system in any 

mine. For a split-mine ventilation system, the stoppings 

closest to the fan, which have the highest static pressure, are 

the most critical because leakage at the fan does not reach the 

active workings and is completely lost. Some leakage at the 

last stoppings, closest to the face, is not a total loss because 

some dilution will still occur, yet those stoppings have to be 

able to withstand higher blast pressure. Poor installation or 

maintenance of a stopping line could quickly result in a large 

percentage of the total ventilation airflow not reaching the face 

area. A test case mine was shown to lose 50% of its total 

ventilation airflow to leakage in the first 12 stoppings (Grau, 

2004). Constant inspection and maintenance of the stopping 
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Figure 5. Split-mine ventilation, (phase 3) three stoppings 

installed with three open crosscuts, high flow fan can be 

installed in bulkhead 

 Figure 6. Large propeller fan mounted in bulkhead 

 Figure 7. Typical repetitive flapping damage caused by 

static pressure across stopping (not blast damage) 

line is essential for a spilt-mine ventilation system to work 

properly and effectively.

 The stoppings installed near the active workings are 

categorized as check curtains, damage resistance is a priority 

over leakage at this stage so the stoppings are hung loosely 

from the roof. Leakage is minor as there is very little static 

pressure generated across the stopping due to the large 

unobstructed openings located nearby. As the mine expands 

and the stopping line is extended with the development faces, 

a permanent, better sealing stopping is warranted due to the 

increase in static pressure and at this point, i.e. leakage, not 

blast damage, becomes the priority (Figure 8). 

 Figure 8. Tightly installed brattice stopping in a largeopening mine [16.8 m × 8.5 m (55 ft × 28 ft)] 

 Because the stopping line is developed parallel to the 

mining direction, production disruptions are minimal due to the 

lack of mining faces or excessive restrictions on travelways. 

In-place stone stoppings can play a dominate role in reducing 

leakage and stopping maintenance. Most of an in-place stone 

stopping’s internal crosscut can be mined except for the last 

round. Stone stoppings should not be considered lost 

production. Only if no other faces are available can the 

material left in place for the stopping be considered lost 

production. Also, the material can be recovered at a later 

date. With the low value of the material, the profit incurred by 

mining the last part of the crosscut should be compared to the 

cost of constructing a stopping to seal the crosscut later, the 

required maintenance on that stopping, and the lower 

effectiveness of the stopping. 

 Split-mine ventilation is very effective for new mines 

because permanent stoppings can be designed and installed 

during the initial development. The effectiveness of this 

system is based on the number of main entries, number of 

open crosscuts, stopping leakage, mine development shape, 

and stopping line location. 

 Numerical modeling of ventilation airflows:

Numerical modeling is one method to estimate the flow rates in 

various entries. A numerical model of various ventilation 

scenarios shows that the number of main entries determines 

the effectiveness of the ventilation system. For this research 

on numerical modeling of large opening room-and-pillar mines, 

Ohio Automation’s ICAMPS MineVent program1

 was used and 

it should be noted that resistance had to be entered at 100 

times the actual value because the model does not work well 

with such low values. A key simplification in numerical 

modeling ignores the airflow momentum, which plays a large 

role in determining flow patterns in large-opening mines. 

Unlike deeper, higher pressure metal mines, airflow that 

reaches an intersection does not split according to resistance 

(pressure drop) of the next branch, but tends to be controlled 

by momentum. This is because the shock loss of changing 

directions even with a low velocity pressure is significantly 

higher than the static pressure drop of the next branch. 

 

1

 Product mention does not imply endorsement by NIOSH 
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 The model reveals that an 8-main mining system with a 

stopping line running down the middle can effectively ventilate 

the two outermost entries. However, a 16-main system with a 

stopping line running down the middle does not effectively 

ventilate the two outermost entries. Using the numerical 

model as a guide with 236 m3

/s (500,000 cfm) as the base 

airflow rate, airflow at the outermost entries was determined to 

be 12.7% [30.0 m3

/s / 236 m3/s (63,300 cfm/500,000 cfm)] of 

total flow in an 8-main system (Figure 9). Results of 10.2% 

[24.1 m3

/s / 236 m3/s (50,900 cfm/500,000 cfm)] of total flow in 

a 12-main system (Figure 10) and only 7.2% [17.0 m3/s / 236 

m3

/s (36,100 cfm/500,000 cfm)] in a 16-main system (Figure 

11) were determined. Even with double the airflow, mines 

using a 16-main system will find it very difficult to get an 

equivalent airflow to the outer entries without using auxiliary 

ventilation. 

 Figure 9. Numerical model ventilation airflow simulation 

of an eight-entry split mine with three open crosscuts 

(flow in 1,000 cfm, divide by 2.118 to get m3/s) 

 Effective use of the split-mine ventilation method 

requires that the number of open crosscuts be kept as low as 

possible to bring the highest volume of air to the apex of the 

mining front. The optimum number of open crosscuts is 

determined by blast damage, ventilation requirements, and 

haulage constraints. Figure 12 shows the relationship 

between the number of open crosscuts to airflow and truck 

travel directions. Limited observations have suggested that 

three to four open crosscuts is the preferred arrangement. 

With five or more open crosscuts, little ventilation airflow 

reaches the mining equipment at the active faces (Figure 13). 

The locations of the open crosscuts are assumed to be at the 

end of the stopping line. 

 Figure 10. Numerical model ventilation airflow simulation 

of a twelve-entry split mine with three open crosscuts 

(flow in 1,000 cfm, divide by 2.118 to get m3/s) 

 Figure 11. Numerical model ventilation airflow simulation 

of a sixteen-entry split mine with three open crosscuts 

(flow in 1,000 cfm, divide by 2.118 to get m3/s) 
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 Figure 12. Possible main truck route to get to most areas 

of the mine with little disruption in travel 

 Figure 13. Numerical model ventilation airflow simulation 

of a sixteen-entry split mine with five open crosscuts (flow 

in 1,000 cfm, divide by 2.118 to get m3/s) 

 Figure 14 represents the ventilation airflows determined 

by numerical models for different entry and crosscut 

conditions. The entries are labeled “1 to 8 Right” or “1 to 8 

Left” starting with the middle two entries called “1 Right” and “1 

Left” and moving outward to “8 Right” and “8 Left”, 

respectively. The airflow distribution for the middle entries is 

very similar for an 8- or 16-entry system with three open 

crosscuts. The outer entries that are farther away from the 

stopping line have progressively larger reductions in ventilation 

airflow. The leading central entries also have low flow, but are 

located near an intersection with high flow rates, so dilution 

should not be a problem. Compared to the 16-entry system 

with three open crosscuts, the 16-entry system with five open 

crosscuts has a significant reduction of total ventilation airflow 

reaching the last open crosscut. This shows the importance of 

maintaining a minimum number of open crosscuts. 

Airflow at Last Open Entry

0

20

40

60

80

100

120

140

160

8 Left

7 Left6 Left

5 Left

4 Left3 Left

2 Left1 Left

1 Right2 Right3 Right

4 Right5 Right

6 Right

7 Right

8 Right

Mains

Airflow (x1000 cfm)

8 Mains 3 Xcuts

16 Mains 3 Xcuts

16 Mains 5 Xcuts

 Figure 14. Flow rate distribution at the last open 

crosscuts from three numerical model ventilation airflow 

simulations 

 Development front shapes considerations: The 

shape of the development front can also play a role in 

determining the effectiveness of the split-mine ventilation 

system. Common mining shapes are the “arrow head,” 

“wedge,” “flat wall,” and “expanding mushroom” (Figure 15). 

The arrow head and wedge development fronts are usually 

high-intensity mining where all faces are developed at the 

same time. The intent of the flat wall mining front is to keep all 

main entries at the same depth. The expanding mushroom 

shape represents an older mine with an abundant number of 

faces that are mined infrequently. 

 Figure 15. Common mining front shapes for large roomand-pillar stone mines 

 For an equivalent number of entries, the arrow head 

shape with a centrally located stopping line has the best flow 

distribution to the active faces. Flow will be best at the 

midpoints of both sides of the arrow and lower at the tip and 

corners (Figure 15). With the wedge shape, which is just one 

side of an arrow head, it will be hard to ventilate both the 

leading and trailing corners at the same time regardless of the 

location of the stopping line. The problematic areas in Figure 

15 have been outlined by triangles. The preferred location of 

the stopping line for the wedge front is closer to the leading 

corner. If the stopping line is located centrally, the leading 

corner will require a dedicated auxiliary fan. 

 The flat-wall shape with a centrally located stopping line 

will have good central ventilation, but poor ventilation at the 

corners. The expanding mushroom mining shape is a poor 

candidate for split-mine ventilation because only the central 
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section will be well ventilated, whereas both long flanks will 

have problems meeting minimum ventilation airflow 

requirements. With multiple mining directions, the expanding 

mushroom would require that multiple stopping lines be 

installed to all the active fronts. Multiple stopping lines would 

adversely affect the haulage system by restricting and 

lengthening possible truck routes. 

Perimeter Ventilation

 The second ventilation method identified by NIOSH is 

perimeter ventilation. This method is strategically different 

from split-mine because it uses a stopping line developed 

perpendicular to the mining direction. The main advantage of 

this system is that it could be installed in a large, mature mine 

that has been extensively benched. The goal of perimeter 

ventilation is to create continuous ventilation airflow across all 

of the active faces, bypassing the bulk of the old mine 

workings. Figure 16 shows a section of a large mine using 

perimeter ventilation. The continued development of in-place 

stone stoppings is required at all times to minimize their impact 

on production and to ensure that they are in-place when 

required for directing ventilation airflow. If in-place stone 

stoppings are not consistently developed, then a great number 

of stoppings have to be installed in a very short timeframe. 

Figures 16 and 17 show how the mining face is developed 

over time. The main concerns with perimeter ventilation are 

road haulage restrictions, maintaining a continuous stopping 

line (brattice and in-place stone) at an appropriate distance 

from the active faces, and reducing blast damage. 

 Figure 16. Perimeter ventilation, (phase 1) developing 

upwards with benching following development of half of 

new in-place stone stoppings, new stopping line 

completed, removal of old stopping line (R = regulator or 

accumulated leakage through stoppings) 

 Stopping line considerations: The use of a continuous 

stopping line to limit air short circuiting requires that the 

haulage road be located entirely in the active face areas. This 

can cause restrictions to haulage efficiency by having longer 

routes. An alternative is to have doors or drive through check 

curtains (both of which greatly increase leakage) to allow 

trucks to travel through the stopping line for a shorter truck 

route. The effectiveness of doors and drive through check 

curtains is very mine-specific and must be determined on an 

individual basis. Doors should be located nearest the face as 

possible to position the leakage where the pressure differential 

is least. 

 Figure 17. Perimeter ventilation, (phase 2) new in-place 

stopping line completed, mined through old in-place stone 

stopping line, benching advanced (R = regulator or 

accumulated leakage through stoppings) 

 Maintaining an appropriate distance between the active 

faces and the stopping line can be a challenge. If the active 

faces are too close, there will be excessive blast damage to 

the stoppings resulting in high corresponding leakages. If they 

are too far away, only a small fraction of the ventilation airflow 

will sweep the active faces. Installing and maintaining 

continuous stopping lines four to eight entries away from the 

active face is challenging because a lot of work has to be done 

in short order to remove the old stopping line and install the 

next one. Developing in-place stone stoppings perpendicular 

to development can adversely affect production because 

longer dead-head entries are created. Figure 16 shows how 

dead-end drifts are mined to create the in-place stoppings. 

The reduction in the number of available working faces during 

development of the in-place stone stoppings requires that all of 

the in-place stoppings cannot be created at the same time. 

 Influence of blast pressure: Another concern with the 

perimeter ventilation method is that the stoppings are located 

at right angles to a majority of the development blasts. Blast 

pressures are assumed to be higher against stoppings that are 

located across an entry than those located parallel to the blast. 

Stoppings that are perpendicular with a blast will bear the full 

force of the explosion, whereas those located around a pillar 

will see only a fraction of the force. 

 Influence of Benching: Benching operations can 

influence the choice of ventilation method. If a mature mine 

has extensively benched the central area of the mine, placing 

a split-mine stopping line could be difficult because of the 

height and size number of the stoppings required. Since 

benching is a primary supply of production for some stone 

mines, it is desirable to implement a ventilation system that 

accommodates benching into its design. 
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 Figure 18. Perimeter ventilation, (phase 3) development 

of half of new in-place stone stoppings, new stopping line 

completed, benching advanced (R = regulator or 

accumulated leakage through stoppings) 

Unit Ventilation

 The third ventilation method identified by NIOSH is unit 

ventilation. Unit ventilation is not a stand-alone system, but 

requires that a preexisting ventilation system is already 

installed. Unit ventilation works off of a preexisting airflow 

system to block off an area for development (Figure 19). Units 

of pillars are created that are surrounded by in-place stone 

stoppings. The unit is mined using a dedicated auxiliary fan 

for ventilation (Figure 20) (Dunn, 1983). To reduce 

recirculation, the fan is located in the fresh airstream of the 

already completed ventilation system. The block of pillars is 

developed diagonally as a wedge shape (Figure 21). During 

development of the block, check curtains may need to be 

installed to guide the airflow to the active heading. 

 Figure 19. Unit ventilation, (phase 1) split mine develops 

airflow pattern, using an auxiliary fan for unit development 

(shaded area is an 8 by 8 unit block) 

 If a split-mine ventilation system is used to develop the 

mine’s initial ventilation airflow, the split-mine can be 

developed faster than the unit block, which has to be mined in 

a diagonal direction. Therefore more than one unit can be in 

production at the same time (Figure 22). As the unit block is 

finished, it can either become the fresh air supply for the next 

unit or it can be sealed off (Figure 23). 

 Figure 20. Axial vane auxiliary fan (note that the fan has a 

reducer that increases airflow momentum with a 

corresponding increase in entrainment and total airflow) 

 Figure 21. Unit ventilation, (phase 2) first stopping 

installed, blue diagonal pillars are unit ventilation, green 

brick pillars are split-mine 

 Benching can occur after development is completed. 

Once the block is finished, it can be completely sealed off. 

The advantage to this is that the mine does not have to 

exchange this unit’s air so the main mine air is exchanged 

faster, thereby reducing worker exposure to airborne 

contaminates. The unit block shown in Figure 19 was 

developed on the fresh-air side of a split-mine mining system 

that uses trucks in the fresh air side. A unit could be 

developed on the return side of the split mine, but because the 

auxiliary fan should be on the upstream side of the ventilation 

system to reduce recirculation, the unit has to be developed 

backward relative to the direction of the split mine. This 

backward development could raise ground control concerns. 

Unit mining can also be used in perimeter ventilation. 
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 Figure 22. Unit ventilation, (phase 3) connection with 

next unit block created (C = check curtain used to course 

the air to the active faces) 

 Figure 23. Unit ventilation, (phase 4) unit almost 

completed, unit can be sealed off or benched as required 

THE VENTILATION QUESTION: “PUSH OR 

PULL”? 

 The two decisions that need to be made for ventilating a 

large opening mine are: (1) should a push (blowing) or pull 

(exhausting) ventilation system be used, and (2) should truck 

routes be located in fresh or exhaust air? These two choices 

are not independent from a production viewpoint, as two of the 

four possible combinations require that doors be installed for 

the ventilation system to work appropriately, assuming that the 

primary crusher is located outside the mine. Trucks running in 

the exhaust returns of a pull ventilation system require that a 

door be installed to stop short-circuiting. Trucks running in 

fresh air of a push ventilation system have the same concern. 

These doors are not more than access doors that trucks have 

to drive through to get to the active section of the mine at the 

start of the shift; the trucks would need to drive through the 

doors with each trip in and out of the mine. 

 The requirement of having to drive through a door twice 

for each truck load of stone cannot be understated. A typical 

mine could have four trucks running, which equates to 

40 round trips each per shift. This would require that the door 

be opened 320 times during a shift. Each time the door opens, 

the ventilation system will be short-circuited for the time that it 

remains open. From a practical standpoint, ventilation doors 

on the main production route quickly get damaged, and repair 

work can get delayed because it interferes with production. 

Therefore, for simplicity only, pull (exhaust) ventilation with 

trucks running in fresh air and push (blowing) ventilation with 

trucks running in exhaust air should be considered. 

 Another question remains: is it more advantageous to 

bring fresh air to the active faces of the mine or to quickly 

remove contaminants from the mine? From an airborne 

contaminants viewpoint, a pull (exhaust) system gets rid of 

blast gases and DPM quickly from the mine, therefore, most of 

the mine is in clean fresh air. The main disadvantage to the 

pull system is that the air reaching the active faces is not pure. 

Thus, a higher total ventilation airflow has to reach the active 

faces to adequately control airborne contaminates. A push 

(blowing) system does get rid of blast gases and DPM quickly 

from the face, but not from the mine as a whole, therefore, 

most of the mine is in contaminant-laden air. The main 

advantage to the push (blowing) system is that clean 

uncontaminated air reaches the active faces. 

 To decide between a push or pull ventilation system, the 

following mine dependant questions have to be answered: (1) 

where are most of the workers located and (2) which workers 

are at the greatest risk from exposure to airborne 

contaminants? Most of the workers are at the active faces and 

along the haulage routes, so providing the cleanest air to the 

face is important. Powder men and shop workers are 

particularly vulnerable to airborne contaminates because they 

spend a large amount of their time outside of vehicle cabs. 

 Diluting a continuous, stationary contaminant source 

(power loader, driller) is the trickiest part of any ventilation 

system. Ventilation airflow has to be consistent and at a high 

enough volume to dilute and transport the contaminants away 

from the stationary source. Having just a face ventilation 

system without a mine-wide or regional system can cause 

excessive recirculation. Any recirculation at this point has a 

detrimental effect on ventilation efficiency. Diluting a mobile 

contaminant source (trucks, load-haul-dump) is not as difficult 

because the contaminants are deposited over a large area and 

these employees are normally in environmental cabs. Having 

an effective mine-wide and regional ventilation system should 

help maintain airborne contaminants below statutory levels. 

CONCLUSION 

 NIOSH has shown that both split-mine and perimeter 

ventilation can be effectively installed in large-opening mines. 

Split-mine ventilation has worked well as the primary 

ventilation system in a new high-intensity mine. Maintaining 

the integrity of the stopping line is the most important factor for 

efficiency of this ventilation method. Perimeter ventilation has 

worked well as a retrofit to a large mature mine that was 

extensively benched before installation. Maintaining the 

existing stopping line while developing a new continuous 

stopping line is a primary factor for determining efficiency of 

the perimeter ventilation method. Use of the unit ventilation 

method has not yet been adequately documented by NIOSH, 

but shows promise for future mines. 

REFERENCES 

Adam, M.E., Brechtel, C.E., Agapito, J.F.T., [1986] Improved 

Stopping, Door and Overcast Construction for Oil 

Shale Mines, Report for the U.S. Bureau of Mines 

contract # J0145020 

Dunn, M.F., Kendorski, F.S., Rahim, M.O., & Mukherjee, A. 

[1983] Testing Jet Fans in Metal/Nonmetal Mines with 

Large Cross-Sectional Airways, Report for the U.S. 

Bureau of Mines contract # J0318015 

Grau, III, R.H., Robertson, S.B., Chekan, G.J., Mucho, T. 

[2004] Raising the bar of ventilation for large opening 

stone mines. Accepted for SME transactions North 
9

America/Tenth Mine Ventilation Symposium, 

Anchorage, AL 

Grau, III, R.H., Robertson, S.B., Mucho, T.P., Garcia, F., & 

Smith, A.C. [2002a] NIOSH research addressing diesel 

emissions and other air quality issues in nonmetal 

mines. In 2002 Society for Mining, Metallurgy and 

Exploration Annual Meeting, Phoenix AZ, Feb. 26-28, 

2002 

Grau, III, R.H., Robertson, S.B., Mucho, T.P., Smith, A.C. & 

Garcia, F., [2002b] Practical techniques to improve the 

air quality in underground stone mine, North 

America/Ninth U.S. Mine Ventilation Symposium, 

Kingston, Ontario, Canada, PP. 123-129, June 8-12, 

2002 

Head, R [2001a] Proper Ventilation for Underground Stone 

Mines. Aggregates Manager, January 2001: 20-22. 

Head, R [2001b] Calculating underground mine ventilation fan 

requirements. Aggregates Manager, April 2001: 6(3): 

17-19. 

Mucho, T.P., Grau, III, R.H., Robertson, R.B. [2001] Practical 

mine ventilation. Presentation at the Safety Seminar for 

Underground Stone Mines, Louisville, KY, Dec. 5. 

Mine Safety and Health Administration (MSHA), U.S. 

Department of Labor [2001] Final Rule 30 CFR Part 57 

NIOSH [2002a] Technology news 499. Using propeller fans to 

improve ventilation in large-entry stone mines. 

Pittsburgh, PA: Department of Health and Human 

Services, Public Heath Service, Centers for Disease 

Control and Prevention, National Institute for 

Occupational Safety and Health. 

NIOSH [2002b] Technology news 500. Using in-place stone 

stoppings to direct air in underground stone mines. 

Pittsburgh, PA: Department of Health and Human 

Services, Public Heath Service, Centers for Disease 

Control and Prevention, National Institute for 

Occupational Safety and Health.