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Improvement of ventilation system in a mining site
1. PROJECT TITLE: IMPROVEMENT OF VENTILATION SYSTEM
PROJECT TYPE: PROBLEM SOLVING
CASE STUDY: BLUE REEF GOLD MINE (GEITA)
STUDENT NAME: MATELE G FABIANO
ADMISSION NUMBER: 150126121935
2. INTRODUCTION
• BLUE REEF GOLD MINE, is a medium scale underground gold mine
located at RWAMGASA village in GEITA region. The mine is about 50
km from GEITA town. It was established on 27/6/1991 under the mine
license which covers an area of 9 hectares.
• In any underground mine development, sufficient ventilation has
huge contribution in production enhances since it creates healthier
and safe working environment but poor ventilation results to several
problems such as suffocation and heat fatique which inturn may lead
to stoppage of operation hence resulting into failure to meet mine’s
production goal.
3. PROBLEM STATEMENT
• There has been a recurring problem of incidences of stoppages of
production due to the ventilation related problems at BLUE REEF
GOLD MINE. For instance, from August to October there had been
production stoppage averaging twice a week. The stoppage of operation
are due to failure f workers to continue to work due to insufficient air.
4. OBJECTIVES
General objective
• The main objective is to assess ventilation parameters and
improvement of system at Blue reef gold mine
Specific Objectives
• To calculate the total quantity of airflow rate required by mine
• To design the primary ventilation system
• To identify the number of factors that hinder good ventilation
5. Project Significance
By end of this project, it will provide beneficial physiological
and psychological effects that enhance employee safety,
comfort, health and morale to workers hence stimulating
production and meeting the company’s goal.
Scope of Project
This project will cover on the primary ventilation system and
the mine atmospheric condition to its completion.
Expected outcome
At the end of this project, the report will provide remedial
measures that will help to
Improve the ventilation system in shaft no2 at BLUEREEF GOLD
MINE
6. LITERATURE REVIEW
VENTILATION
• This refers to the control of air movement, amount and its direction
therefore underground mine ventilation provides a flow of air to the
underground workings of mine of sufficient volume to dilute and
remove dust, noxious gases and to regulate temperature.
SIGNIFICANCE OF VENTILATION
• Provision of continuous supply of fresh outdoor air(oxygen) for
humans and engine combustion
• Remove or dilute airborne contaminants
• Reduce potential fire or explosion hazards
• Maintenance of temperature and humidity at comfort level
7. LITERATURE REVIEW CONT
TYPES OF VENTILTION SYSTEM
Primary/ flow through ventilation system
• This is main ventilation circuit for mine. Air enters the mine from
surface via shaft, ventilation raise or adit.
There are three aspects involved in flow-through ventilation system;
• The introduction of fresh air into underground mine,
• Proper distribution of this air, and
• The flow/ circulation of the air.
8. LITERATURE REVIEW CONT
Factors to consider for primary ventilation system
• Selecting the main ventilation inlets and outlets,
• Determine airflow requirements,
• Specify fan location
• Determine airflow resistance for each branches
10. LITERATURE REVIEW CONT
Secondary/auxiliary ventilation system
• This takes air from the flow-
through system and distributes it to
the mine workings which are not
easily accessible, via temporarily
mounted ventilation fans, venturies
and disposable fabric or steel
ducting. The auxiliary fan and duct
systems may be either forcing
systems, where fresh air is pushed
into mine headings, or exhausting
systems that draw out contaminated
air. Fig02:diagram for secondary
ventilation system
11. LITERATURE REVIEW CONT
MINE VENTILATION FAN
This is a device that utilizes the mechanical energy of a rotating impeller to produce both
movement of the air and an increase in its total pressure. The mine ventilation fan creates
a pressure difference that makes air current to flow from high pressure region to low
pressure region.
TYPES OF MINE VENTILATION FAN
There are many types of mine ventilation fans which are used depending on their
performance ability which are
Main fans(25-450𝑚3/s at pressure 400Pa-90kpa from power rate 50kw to 4100kw)
Auxiliary fans(15𝑚3
/s at 2.1kpa from power rate 4kw to 45kw varies in diameter from
380-760mm)
Scrubber fans
Booster fans(60-90𝑚3
/s @30kpa)
12. LITERATURE REVIEW CONT
AIR PRESSURE
Fans create a pressure differential that causes the air to flow through
the workings. This difference in pressure between two points is
referred as Ventilating pressure which obey o the following rules
The air will always flow from a high pressure point to a low
pressure point, the air will continuously flow as the pressure is
maintained
The larger the pressure difference between these two points, the
greater the quantity of air will flow. Under assumption of resistance
between these two points kept unchanged.
The resistance to the pressure reduces Ventilating pressure, such
as pressure is used up overcoming the resistance to airflow
If the pressure difference between these two points is constant
and the resistance to airflow between these points is increased, the
air quantity will decrease
13. LITERATURE REVIEW CONT
A. STATIC PRESSURE
This is potential or stored energy of air often called bursting pressure.
The static pressure is also known as pressure which is exerted by air on
wall of the containing vessel.
Fig03: static pressure inside the duct
14. LITERATURE REVIEW CONT
B. VELOCITY PRESSURE
This is kinetic energy which is possessed by air due to its motion. The
faster the air moves the larger the velocity pressure is and vice versa.
The velocity pressure can be calculated as
VP=
1
2𝑣2ρ
Where VP= ventilating pressure (Pa)
V=airflow velocity (m/s)
ρ=air density(kg/𝑚3
)
15. LITERATURE REVIEW CONT
C. TOTAL PRESSURE(TP)
This is algebraic sum of velocity pressure(vp) and static pressure(sp)
and measured parallel direction to airflow.
TP=VP +SP Where TP=Total pressure (Pa)
VP=Velocity Pressure(Pa)
SP=static pressure (Pa)
16. LITERATURE REVIEW CONT
FUNDMENTALS OF AIRFLOW
The quantity of air that will flow
through a system(duct or mine
workings) is dependent upon
• The difference in pressure at the
start of system and at the end of
the system
• The size of opening
17. LITERATURE REVIEW CONT
AIR FLOW EQUATION
• No pressure difference btn points no air flowing
• Pressure is zero also the quantity of air flowing is zero
• Therefore the pressure is directly proportional to the quantity of airflow
P α Q………………..i
P=RQ…………………ii
The sign of proportionality is removed by introducing a constant R known as
resistance to airflow
Where P=pressure (Pa)
Q=Quantity of air(𝑚3)
R=Resistance (N𝑠2/𝑚8)
18. LITERATURE REVIEW CONT
VENTILATION EQUATION
• This is true for laminar airflow and not true for turbulent airflow
• Noted that in fully turbulent flows, to double the quantity of air
flowing then pressure four times the original was required.
• The pressure is proportional to the quantity squared
P=R𝑄2
This is called the ventilation eqaution.
20. LITERATURE REVIEW CONT
• In parallel circuit
• Airways are in parallel when
they have common inlet and out
common outlet
• PT=PA=PB
21. LITERATURE REVIEW CONT
The ventilation system must be sufficient to deal with the contaminants
released during mining. The prime contaminants produced during mining
operation are;
Mine Gas and fumes,
Dust ,
Heat and
Temperature
22. DATA COLLECTION
• The following data have been collected by consultation to the mine
engineer at site
Height of the shaft no2 =120m
Horizontal distance from shaft bottom part to the working area
=40m,50m,80m
The number of workers going underground ranging from 4-7
depending on degree of job to be executed.
23. DATA COLLECTION
According to P.du.Toit (2007) ventilation standards guidelines are;
Stopes
• Wet bulb temperature between…..27.5-29.5℃ not exceeding 32℃
• Air velocity………………………0.25m/s(minimum)
• Dust………………………………below 1mg/m3
Development
• Wet bulb temperature……...27.5-29.5℃, not exceeding 32℃
• Air quality deliver………….1.2m/s
• Dust…………………………below 1mg/m3
25. DATA COLLECTION CONTINUE
1: A table showing Gas Concentration in various working places
Station NO2(ppm) CO(ppm) NH3(ppm) O2(%)
1180 Sump 1.80 15.00 0.00 19.00
1100 SW 1.1 10.00 7.00 20.5
1120
Dev(Haulage
)
0.7 5.00 0.00 19.7
1120 FE 2.4 11.0 1.00 19.1
26. DATA COLLECTION CONT
2: A table showing air velocity and airflow rate.
Station Air velocity
(m/s)
Airflow rate
(m3/s)
THE AREA OF
THE FACE(m2)
1180 Sump 0.2 5.1 3.6×6.0=21.6
1100 SW 0.27 4.49 3.5×4.7=16.63
1120
Dev(Haulage)
0.51 3.264 3.2× 2.0=6.4
1120 FE 0.28 4.4772 4.1×3.9=15.99
1100-381 0.2 2.7125 4.3*3.1=13.56
27. DATA COLLECTION CONT
A table showing temperature(°∁) in various working places
Stations Wet –Bulb temp(°𝑪) Dry –Bulb temp(°∁)
1180 Sump 29.6 28.3
Portal 30.4 25.7
1100 SW 30.2 26.4
Dev(Haulage) 29.5 27.4
1120 FE 32.4 29.0
1100-381 32.5 29.3
29. DATA ANALYSIS
THE PRIMARY CIRCUIT:
The primary circuit consists of the three branches,A including
1120FE,1100-381 and 1120 Dev, B including QA and 1100SW and C
comprises QB and 1100 Sump.
The analysis of each junction is done by considering the kirchoff’s first
law which can be stated as “the algebraic sum of the quantities at any
junction in a circuit system is equal to zero”
At junction A
QA-Q3-Q4=0 QA=Q3+Q4= 4.4772+2.7125
QA=7.1897m3/s
30. DATA ANALYSIS
At junction B, the total quantity at this point is
QB-Q2-QA =0 QB=Q2+QA=7.1897+4.49
QB=11.6797m3/s
At the junction C
QC-QB-Q1=0 QC=QB+Q1=11.6797+5.1
QC=17.0797m3/s
34. DATA ANALYSIS
• Resistance for Exhaust Shaft
K=0.07N𝑠2/𝑚4
C=5.6m
L=120m
A=1.92𝑚2
R=
0.07∗5.6∗120
1.923 =6.646N𝑠2/𝑚8
35. DATA ANALYSIS
The NVP of the mine is calculated as follows
Mean air density of intake shaft ρ𝑖𝑛=1.2kg/𝑚3
Mean air density of exhaust shaft ρ𝑒𝑥=1.121kg/𝑚3
NVP=gh(ρ𝑖𝑛- ρ𝑒𝑥)
NVP=9.8*120(1.2-1.121)Pa
NVP=92.904Pa
36. DATA ANALYSIS
The minimum mechanical ventilating pressure to be added to the system
P+NVP=R𝑄2
P=R𝑄2 − NVP
P=3.15*17.07972
-92.904
P=826.00Pa (minimum static head loss of the system)
(Assumption the ventilating duct to be used for delivering the air should be
of very low resistant to flowing i.e neglected)
37. DATA ANALYSIS
Total pressure/head losses(Ht) is the sum of all energy losses occur
within the vent circuit.
Ht =Hs + Hv; Hs=static head loss, Hv=mine velocity head loss
Hs= Friction losses + Shock losses =826.00Pa
Dynamic pressure drop of the intake airway
Hv=0.5*1.2*
122
2∗9.8
=4.41pa
Total pressure Loss to be overcome =Hs+Hv=826+4.41=830.41Pa
38. DATA ANALYSIS
• Based on operating point of the mine, the required power of the fan
can be calculated as follows(Hartman et al 2002)
N=
𝑄𝑡∗𝑃𝑡
η1η2∗1000
where Qt =total air quantity, Pt= total head loss
η1 = fan efficiency, η2= electromotor efficiency and N= required fan
power. η1=atleast 65% and η2=atleast 70% to meet ventilation
requirement in u/g(ASHRAF,2004)
Hence the fan requirement power =
17.078∗830.41
0.65∗0.7∗1000
=31Kw
39. DATA ANALYSIS
• The designed primary ventilation system for Blue reef Gold mine
44. DATA ANALYSIS
4.0 The graph of the dust exposure against different workers
0
0.02
0.04
0.06
0.08
0.1
0.12
u/g charging Charging crew Exploration drilling Productive drilling Safety surveying crew
dust
concentration
mg/m3
TWA OEL/PEL
45. DATA ANALYSIS
From the graph1.0 above, the standard air temperature(wet bulb temperature) is
required not to exceed 320C, from the actual measured wet bulb temperature, it
shows that some working faces experiencing high temp level than the standard of
the max 32 due to the depth approaching the core and blasting which is done often
From the graph 2.0 it shows that the velocity of air varies from one drive to
another, due to the resistance offered at each drive. The air leakage also became
the reduction factor for velocity variation.
From graph 4.0 it shows that the charging crew experiencing more dust than OEL
, due to re-entry after blasting and also productive drillers get exposed to the dust
above OEL.
46. CONCLUSION
• From the data collected and analyzed above it can be concluded that
• the natural ventilation system of Blue reef Underground Mine is not
effective enough to dilute and remove contaminants i.e. dust, heat
and fumes, to clear off the mine at a reasonable time after blasting
and during mining. This initiates the establishment of mechanical
ventilation of the total head 830.41Pa to provide support to the
natural ventilating pressure in dilute and remove contaminants out of
the mine
47. RECOMMENADTION
The flexible ventilating duct with diameter 350mm should be used
Flexible vent duct, bending causing
shock loss should be minimized as
small as possible
48. RECOMMENADTION
The main fan selected should be capable of delivering 17m3/s at
minimal pressure of 830.41Pa and dissipating power of 31kw
The prevention maintenance program should be implemented for
drilling equipment to reduce dust emission,
There should be a frequent testing and monitoring of mine
ventilation atmosphere for concentration of dust, diesel particulate
matters, gases, temperature, humidity and velocity for each working
face in order to determine any changes in underground atmospheric
condition,
Raise bore drilling for ventilation
49. REFERENCES
• Hazim B. Awbi (2008), Ventilation system: Design and Performance,
Psychological Press, United Kingdom
• William Cory (2010), Fans and Ventilation: A practical Guide, Elsevier,
• Howard.L.Hartman,J.M.M, 2002;introductory to mining engineering 2𝑛𝑑
ED.
• Robinson, R. (1989). The use of Booster Fans and Recirculation Systems for
Enviroment Control in British Coal mines. Florida: Oxford Press.
• P. Du. Toit. (2007). South Africa Mining Laws and Regulations: Handbook
Volume1 . Pretoria: South Africa Mining Society.
• Banerjee, S. P. (2003). Mine Ventilation. Lovely prakashan: Dhanbad,India.
• AMC Consultants. (2005). Basic Mine ventilation. Melbourne: AMC
Consultants Pty Ltd.
