This document is a thesis submitted by Rasiel Robert to the Mineral Resources Institute in partial fulfillment of an Advanced Diploma in Environmental Engineering and Management in Mines. The thesis investigates and proposes methods to moderate underground dust emission at Tanzanite One Mining Company in Manyara Region. It includes an introduction covering background on tanzanite mining and dust issues. It then reviews literature on dust, its effects, and moderation methods. The methodology describes how dust data was collected through sampling. Data collection, analysis and interpretation are presented. The thesis provides a comprehensive study of underground dust emission and potential solutions.

1. INVESTIGATION AND MODERATION OF UNDERGROUND DUST EMISSION
AT TANZANITE ONE MINING COMPANY IN MANYARA REGION
Rasiel Robert
Reg no. 810 MID 12
Advance Diploma in Environmental Engineering and Management in Mines
Mineral Resources Institute
May, 2015

2. INVESTIGATION AND MODERATION OF UNDERGROUND DUST EMISSION
AT TANZANITE ONE MINING COMPANY IN MANYARA REGION
By
Rasiel Robert
Advance Diploma in Environmental Engineering and Management in Mines
A Project work Submitted in Partial Fulfillment of the
Requirements for the Advance Diploma in Mining Engineering of the Mineral
Resources Institute
Mineral Resources Institute
May, 2015

3. i
CERTIFICATION
The undersigned certify that they have read and hereby recommend for acceptance by the
Mineral Resources Institute a project work titled: Investigation and Moderation of
Underground Dust Emission at Tanzanite One Mining Company at Manyara Region in
fulfillment of the requirements for the Advance Diploma in Environmental Engineering and
Management in Mines of the Mineral Resources Institute.
FRANK PAUL
Prof/Dr/Mr./ Ms /Eng.
(Supervisor)
Date: …………………………………
MKANGO
Prof/Dr/Mr./Ms/Eng.
(Head of Department)
Date: ……………………………...
J. MAKENA
Prof/Dr/Mr./Ms.
(Project Coordinator)
Date…………………………….

4. ii
DECLARATION AND COPYRIGHT
I, Rasiel Robert, declare that this thesis is my own original work and that it has not been
presented and will not be presented to any other Institute/Learning Institution for a similar or
any other Advance diploma award.
Registration Number
……………………...
Signature
……………………
Date
………………………
Signature------------------------------------------
This project work is copyright material protected under the Berne Convention, the Copyright
Act 1999 and other international and national enactments, in that behalf, on intellectual
property. It may not be reproduced by any means, in full or in part, except for short extracts
in fair dealings, for research or private study, critical scholarly review or discourse with an
acknowledgement, without the written permission of the Unit of Research, Consultancy and
Short courses, on behalf of both the author and the Mineral Resources Institute

5. iii
ACKNOWLEDGEMENT
I would like to give the glory and honor to my almighty God for giving me hope in times of
adversity, piece in times of chaos, serenity in time of trials and endless source of grace,
courage and strength to step into the unknown every time the going got through. Without
God my Labor would be in vein. I thank him for being the source of my success.
I would like to thanks my family for their financial supporting provided to me during
industry practical training, God bless them for their support to me, I really appreciate the
support.
I would like to thank the whole management and staff of Tanzanite mining company for their
support gave me during the period of conduct my project, they cooperate with me in
perpendicular way, much thanks for them.
Finally I would like to thanks the management of Mineral Resource Institute for their effort
applied toward my project, I really appreciate their effort, also much thanks for their
academic support for us student.

6. iv
DEDICATION
I would like to dedicate this project work to my family members, staffs of mineral resource,
ministry of energy and minerals institute, and my school mate at mineral resource institute

7. v
ABSTRACT
Underground Tanzanite mining operations in Mirelani continue to increase productivity as
mining equipment and practices are improved. Unfortunately, increased production also
results in the potential for increased respirable dust generation and worker exposure. In
response, Company operations are applying basic controls at elevated levels and looking to
emerging technologies in an effort to better control respirable dust levels.
Ventilating air and water sprays remain the basis of dust control strategies for both working
and continuous mining operations, and the level of application for these controls continues to
increase. In addition, new technologies are emerging that have the potential to further reduce
dust levels. From the study has been conducted to find out the factor which affect tanzanite
production and came out with the problems of dust emission during underground mining
activities, and therefore to introduce a method of moderating the problems of dust emission.
This thesis consists of introduction, problem statement, objective and methodology, data
collection and data interpretation, conclusion and recommendation, which will be a simple
summary of this thesis.

8. vi
TABLE OF CONTENTS
CERTIFICATION ...................................................................................................................i
DECLARATION AND COPYRIGHT..................................................................................ii
ACKNOWLEDGEMENT .....................................................................................................iii
DEDICATION........................................................................................................................iv
ABSTRACT .............................................................................................................................v
TABLE OF CONTENTS.......................................................................................................vi
LIST OF TABLES..................................................................................................................ix
LIST OF FIGURES.................................................................................................................x
LIST OF ABBREVIATIONS................................................................................................xi
CHAPTER ONE......................................................................................................................1
1.0. INTRODUCTION............................................................................................................1
1.1. General Introduction.......................................................................................................1
1.1.1 Location and Background.............................................................................................1
1.1.2 Location and Access.....................................................................................................2
1.1.3 General Geology of Tanzanite......................................................................................3
1.1.4 Dust...............................................................................................................................4
1.2 Problem Statement...........................................................................................................4
1.3 Objectives ........................................................................................................................5
1.3.1 Main Objective .............................................................................................................5
1.3.2 Specific Objective.........................................................................................................5

9. vii
CHAPTER TWO.....................................................................................................................6
2.0. LITERATURE REVIEW................................................................................................6
2.1.0 Dust...............................................................................................................................6
2.1.1 Emission of dusts..........................................................................................................7
2.1.2 Type of dust ..................................................................................................................7
2.2.3 Grade of Dust................................................................................................................8
2.1.4 Aim of Dust Control.....................................................................................................9
2.1.5 Importance to Control Dust in Underground Mines...................................................10
2.2.6 Effects of dust.............................................................................................................10
2.2.7 Effect of dust in water.................................................................................................10
2.2.8 Dust Moderation Methods ..........................................................................................11
2.2.9 Airborne Dust Capture Systems method ....................................................................11
2.3.0 Methods of Atomization.............................................................................................13
2.3.1 Chemical Additives to Control Droplets ....................................................................14
2.3.2 Wet Dust Suppression.................................................................................................15
CHAPTER THREE ..............................................................................................................18
3.0 METHODOLOGY..........................................................................................................18
3.2. Dust data collection. .....................................................................................................18
3.3 Dust sampling................................................................................................................18
CHAPTER FOUR .................................................................................................................20
4.0 DATA COLLECTION, ANALYSIS AND INTERPRETATION ..............................20
4.1 Data Collection and Analysis ........................................................................................20

10. viii
4.2. Data Interpretation........................................................................................................24
CHAPTER FIVE...................................................................................................................28
5.0 RESULTS AND DISCUSSION......................................................................................28
CHAPTER SIX......................................................................................................................29
6.0 CONCLUSION AND RECOMMENDATION.............................................................29
6.1. Conclusion....................................................................................................................29
6.2 Recommendation ...........................................................................................................29
REFERENCES ......................................................................................................................30
APPENDICES .......................................................................................................................31

11. ix
LIST OF TABLES
TABLE page
Table 1: Table show data of test # 1........................................................................................20
Table 2: Table show data of test # 2........................................................................................21
Table 3: Table show data of test # 3........................................................................................22
Table 4: Table show data of test # 4........................................................................................23

12. x
LIST OF FIGURES
FIGURE page
Figure 1: Location of Tanzanite one mining company .........................................................1
Figure 2: Location of Tanzanite one mining the four blocks ................................................2
Figure 3: Sketch map showing gemstone mineralization in the Mozambique belt
of Tanzania ............................................................................................................3
Figure 4: Dust emission.........................................................................................................7
Figure 5: It show the size of the particle that grouped according to the human
threats.....................................................................................................................9
Figure 6: Collision between dust particle and water droplets .............................................12
Figure 7: Effect of droplet size on dust particle impingement ............................................13
Figure 8: Contact angle resulting from a liquid meeting a solid surface.............................14
Figure 9: The use of water to suppress dust ........................................................................16
Figure 10: Sleap stream effect...............................................................................................17
Figure 11: Components of dust collection system ................................................................19

13. xi
LIST OF ABBREVIATIONS
Abbreviations Meaning
MEM Ministry of Energy and Minerals
MRI Mineral Resources Institute
Ca2Al2O.AlOH[Si2O7][SiO4] Zoisite
ACGIH American Conference of Governmental Industrial
Hygienists
BOHS British Occupational Hygiene Society
IPT Industrial Practical Training
STAMICO State Mining Corporation
KIA Kilimanjaro international airport
TGI Tanzania Gemstone Industries Ltd
NEMC National Environmental Management Council
NE North East
PPM Particle per million
H2O Water
CH4 Methane
H2S Hydrogen sulphate
N2 Nitrogen gas
θ Angle

14. 1
CHAPTER ONE
1.0. INTRODUCTION
1.1. General Introduction
1.1.1 Location and Background
Tanzanite one Mine company is an underground mine located in Manyara Region northeast of
Tanzania, 16kilometers from Kilimanjaro international airport (KIA). It was discovered in the
Mererani Hills of Manyara Region in Northern Tanzania in 1967, near the city of Arusha and
Mount Kilimanjaro. Tanzanite One Mining Ltd is owned by Richland Resources, but a 2010 law
in Tanzania required them to cede 50% ownership of their mining license to the Tanzanian State
Mining Company (STAMICO).Tanzanite is a trade name that was first used by Tiffany and
Company for gem-quality specimens of the mineral zoisite (Ca2Al2O.AlOH[Si2O7][SiO4]) with
a blue color. Tiffany could have sold the material under the mineralogical name of blue zoisite
but they thought the name Tanzanite would stimulate customer interest and be easier to market.
Figure 1: Location of Tanzanite one mining company

15. 2
Various individuals have been credited with the discovery of Tanzanite including Manuel
D’Souza and Ali Juuyawatu who came across the then unknown blue mineral in 1967 He shared
his find with Manuel D’Souza, a tailor by profession and prospector by passion, who was
looking for rubies in the region. From 1968 to 1971, Ali Juuyawatu, a farmer, started mining in
the area now known as Block C and the government nationalized all mining activities were
putted under the control of Tanzania Gemstone Industries Ltd (TGI), in 1972 the State Mining
Corporation (STAMICO) was formed and took over control of TGI until 1983.
In 1990 the government divided the area into four main blocks Block C was awarded to
Graphtan Ltd, predominantly focused on mining graphite, at the end of 1998, AFGEM Ltd was
issued a prospecting license for the Block C and later in 2001 acquired a mining license.
Figure 2: Location of Tanzanite one mining the four blocks
Tanzanite one mining company consists of a process plant, waste rock dumps, tailing
containment, water management ponds, and associated facilities.
1.1.2 Location and Access
Tanzanite is mined in vicinity of Mirelani a mining village situated on the west flank of the
Lelatema mountain range in Tanzania East Africa as show in ( Figure 1) situated 16km south
east of Kilimajaro international airport. The deposit is situated between latitude 30
,33’’
and 30

16. 3
33’’
5’
S and longitude 360
57’’
and 370
4’’
E the nearest Arusha and Moshi accessible from mine
via a 16km dirt road to Kilimanjaro international airport followed by 45km stretch of tar road.
1.1.3 General Geology of Tanzanite
The Proterozoic (1900-700 Ma) lithostratigraphic units within the Mozambique Belt of Tanzania
stretch in a N-S direction east of the Tanzanian Craton and are known to host most of the
coloured gemstones. This paper concentrates on the Merelani Tanzanite mining area lying near
the contact between the volcanic and the high-grade metamorphic rocks of the Mozambique Belt.
Figure 3: Sketch map showing gemstone mineralization in the Mozambique belt of Tanzania
1) Longido, 2) Manyara, 3) Babati, 4) Merelani, 5) Lelatema, 6) Tiriri, 7) Landanai, 8) Umba, 9)
Mvuha, 10) Magogoni, 11) Namaputa, 12) Nabunju, 13) Sumbawanga,14) Mpwapwa, 15) Kilosa
and 16) Loliondo (After Malisa and Muhongo 1990).

17. 4
The supracrustal rocks in the Merelani area very similar to the rocks found elsewhere in the
Mozambique Belt, consisting of psammitic, pelitic and psammo-pelitic gneisses, crystalline
limestones, and to a lesser extent granite pegmatites and quartz veins. After the main phase of the
Pan African tectonothemal event, these rocks have in some areas suffered alteration as reflected
in their chemical and mineralogical composition as a result of the hydrothermal processes.
The mineralization lies within the hydrothermally altered zone along the Lelatema fault zone
with a northerly plunging regional scale fold structure. High quality blue zoisite (tanzanite)
occurs in boudinaged quartz veins within the graphiterich hydrothermally altered gneisses.
However, honey- yellow coloured with other colours may also be found outside the boudinaged
structures. Inhalation of graphitic dust and silica particulates is the main problem miners face
during extraction of the gems from the host rocks. Detailed studies on the geology of Merelani
area is discussed by Malisa (1987) while the paragenesis of tanzanite, its crystallographic
structure, mode of occurrence, the tectonic setting are described by Malisa and Koljonen (1986),
Sundberg et al. (1988), Malisa and Muhongo (1990), respectively.
1.1.4 Dust
Are the solid particles that are suspended in air, or have settled out onto a surface after having
been suspended in air. The terms dust and particulate matter (PM) are often used fairly
interchangeably, although in some contexts one term tends to be used in preference to the other.
1.2 Problem Statement
Tanzanite one mining has been facing a problem of underground dust emission during the
mining activities. This is due to failure of dust moderation, poor control systems and inadequate
method of dust suppression. The aim of this project is to investigate the amount of dust emission
during underground mining activities and techniques required to improving dust emission as to
meet international and national standards.

18. 5
1.3 Objectives
1.3.1 Main Objective
The aim of this project is to examine the dust emission based on the principle of environmental
conservation consequently to moderate the amount of dust emitted and leave the working area
safe.
1.3.2 Specific Objective
i. To establish airborne dust capture systems method basing on the particle size emitted
ii. To use of wet dust suppression method with standard calibrated horse pipes
iii. To conduct Dust Collection techniques

19. 6
CHAPTER TWO
2.0. LITERATURE REVIEW
2.1.0 Dust
Dust is the general name for minute solid particles of a diameter of less than 500 micrometers. In
construction, destruction, and renovation situations, dust of differing sources poses a serious and
recognized health risk to workers causing acute and chronic diseases such as silicosis and
asbestosis. In addition to the health risk, dust emission also poses a threat with its ability in some
sectors to be flammable.
From the British Occupational Hygiene Society (BOHS) Technical Committee studied the "dust
yield" defined as "the mass of aerosol produced per mass of powder dropped" (BOHS, 1995). It
was shown that initially increasing the mass increases the dust yield, but a point is reached when
the dust produced per unit mass levels off and then decreases. Other studies Hazard Prevention
and Control in the Work Environment confirmed this (Breum, 1999), and one concluded that
"dust generation can be minimized by having powders fall as large, discrete slugs instead of a
stream of small clumps; slugs should be as large as possible to minimize the exposure of the
powder to the airflow" (Heitbrink et al., 1992). The explanation is that with higher material
flow, there is more material at the centre of the falling mass, and this central part is less exposed
to surrounding air, and hence less likely to disperse.

20. 7
Figure 4: Dust emission
2.1.1 Emission of dusts
Most of dust at Tanzanite one emitted during drilling and blasting. Dust exposure is dependent
on the amount of dust emitted, which depends on the physical and chemical characteristics of the
material and the methods of handling of the material. Other causes of underground Dust
exposure at tanzanite one generally occurs during the following activities, Through the breaking
of ores by grinding for a simple transport to skip point, During drilling and blasting process
Drilling and during Loading and Mucking, Drilling & Bolting, Ore passes, Crushers, Backfill
Process.
2.1.2 Type of dust
Dust is produced in a very wide range of sizes. Larger, heavier particles tend to settle out of the
air and onto a surface and smaller, lighter particles have a tendency to hang indefinitely in the
air. There are two main types of dust that exist on a worksite like Fibrogenic dust, inert dust.

21. 8
Fibrogenic dust: is so named because it is a kind of dust that has fiber like tendencies.
Fibrogenic dust is biologically toxic and if retained in the lungs can impair the lungs’ ability to
function properly.
Inert dust: is defined as any dust containing less than 1% of quartz content. Typically, and
health effects caused by inert dust are potentially reversible, as opposed to the Fibrogenic dust’s
more permanent effects. However, inert dust has the potential to incomprehensible visibility,
cause unpleasant deposits in exposed bodily orifices, and potentially injure mucous membranes
or the skin with some sort of chemical action.
2.2.3 Grade of Dust
Dusts are grouped according to its particle size. For occupational health purposes, dust is
classified by its size into the three categories of respirable dust, inhalable dust, and total dust.
Respirable dust; is the kind of dust that is small enough to penetrate deep into the lungs and
bypassing the nose, throat, and upper respiratory tract. It has size of less than 5µm or equals to
5µm, which is about 1/12th
the width of the average human hair.
Inhalable dust; is dust of a median size of 10 µm that is trapped in the nose, throat, and upper
respiratory tract. Total dust; it includes all airborne particles, without regard to size or
composition.

22. 9
Figure 5: It show the size of the particle that grouped according to the human threats
2.1.4 Aim of Dust Control
Control systems are used to reduce dust emissions. Although installing a dust control system
does not assure total prevention of dust emissions, a well-designed dust control system can
protect workers and often provide other benefits, such as:-
 Preventing and reducing risk of dust explosion or fire
 Increasing visibility and reducing probability of accidents
 Preventing unpleasant odors from blasting and other mining activities
 Reducing cleanup and maintenance costs since of good ventilation from duct moderation
 Reducing equipment wear, especially for components such as bearings and pulleys on
which fine dust can cause a "grinding" effect and increase wear or abrasion rates
 Increasing worker morale and productivity because of the dust control in extent
 Assuring continuous compliance with existing health regulations (NEMC or WHO)
 Proper planning, design, installation, operation, and maintenance are essential for an
efficient, cost-effective, and reliable dust control system.

23. 10
2.1.5 Importance to Control Dust in Underground Mines
Dust control is necessary due to health hazards, industrial problems and environmental problems.
Excessive dust emissions can cause such health issues as occupational respiratory diseases; eye,
nose, and throat pain or irritation; and skin irritation. In addition, dust is an industrial problem.
With its potential risk of dust explosions and fires, it can potentially damage worksite equipment,
it impairs visibility, it can cause unpleasant odors, and it is a potential problem in community
relations.
As far as health hazards to workers, this occurs when workers are exposed to excessive amounts
of harmful dusts. The harmfulness is dependent on the composition of the dust (i.e. chemical or
mineralogical), the concentration of the dust (either by weight or quantity of dust particles), the
size and shape of the particle (i.e. fibrous or spherical), and lastly, the exposure time.
2.2.6 Effects of dust
The investigation done at tanzanite one mining proves that most of the people admitted to the
company dispensary are suffered from dust exposure diseases. Both found with the lung problem
caused by the dusts. Dust from mining can make it difficult to breathe. Large amounts of dust
can make the lungs fill with fluid and swell up. Signs of lung damage from dust include: sore
throat, shortness of breath, fever, chest pain and loss of appetite
2.2.7 Effect of dust in water
The dust will possibly deposit in underground water bodies, such as river and underground
springs. It increase the sediment in the water body, the particle contain different types of metal it
can change the pH of the water bodies. The alteration of the pH will harm the underground living
organisms which are the biodiversity to our environment and which help in mineralogy process.

24. 11
2.2.8 Dust Moderation Methods
There are so many dust control methods and it varies, based on budget, desired level of
effectiveness, and structural constraints these are:
 To establish airborne dust capture systems method basing on the particle size emitted
 To use of wet dust suppression method with standard calibrated horse pipes
 To conduct Dust Collection techniques
2.2.9 Airborne Dust Capture Systems method
Airborne dust Capture systems work on the principle of spraying very small water droplets into
airborne dust. When the small droplets collide with the airborne dust particles, they stick to each
other and fall out of the air to the ground.
This collision between the particles occurs due the factors which involve both the water and the
dust particles. As a dust particle and water particle approach each other, the airflow could move
the particle around the droplet; have a direct hit on the droplet, or barely graze/abrasion the
droplet.
This factor leads to the second factor, in which droplets and particles of the same sizes have the
best chance of a collision (slipstream effect). If a droplet is smaller than the dust particle or vice
versa, then they may never collide and instead just be swept around each other.
The last factor is the dependence of an electrostatic force on a droplet and how the path is
affected by this force. Like with magnets, similar charged particles repel each others. Thus it is
advantageous to have the particles either both neutrally charged (so that they neither repel nor
attract one another) or oppositely charged (so that they attract one another) in order to increase
the likelihood of a water and particle collision.
In this approach, very fine water droplets are sprayed into the dust after it is airborne. When the
water droplets and dust particles collide, agglomerates are formed. When these agglomerates
become too heavy to remain airborne, they settle.

25. 12
Figure 6: Collision between dust particle and water droplets
The collision between dust particles and water droplets occurs due to the following two factors:-
 Impaction/interception and Droplet size/particle size
i. Impaction/Interception
When a dust particle approaches a water droplet, the airflow may sweep the particle around the
droplet depending on its size, trajectory, and velocity; the dust particle may strike the droplet
directly, or barely graze the droplet, forming an aggregate.
ii. Droplet size/particle size
Droplets and particles that are similar in size have the best chance of colliding. Droplets of water
which are smaller than dust particles or vice versa may never collide but just be swept around
one another particles.

26. 13
Figure 7: Effect of droplet size on dust particle impingement
For optimal agglomeration, the particle and water droplet sizes should be roughly equivalent.
The probability of impaction also increases as the size of the water spray droplets decreases,
because as the size of the droplets decreases, the number of droplets increases by (Rocha 2005).
When wetting the bulk ore to achieve airborne dust prevention, droplet sizes above 100
micrometers (µm) (preferably 200 to 500 µm) should be used. In contrast, for airborne dusts
uppression, where the goal is to knock down existing dust in the air, the water droplets should be
in similar size ranges to the dust particles. The intent is to have the droplets collide and attach
themselves (agglomerate) to the dust particles, causing them to fall from the air. To achieve this
goal, droplets in the range of 10 to 150 µm have been shown to be most effective.
2.3.0 Methods of Atomization
Atomization is the process of generating droplets by forcing liquid through a nozzle, which is
accomplished by one of two methods. Hydraulic or airless atomization controls droplet size by
forcing the liquid through a known orifice diameter at a specific pressure. This method utilizes
high liquid pressures and produces relatively small- to medium-sized droplets in uniformly
distributed fan, full cone, or hollow cone spray patterns.

27. 14
Hydraulic fine spray nozzles are preferred in most areas because operating costs are lower since
compressed air is not required. Air atomizing controls droplet size by forcing the liquid through
an orifice at lower pressures than the hydraulic atomizing method, by using compressed air to
break the liquid into small droplets. This method produces very small droplets and uniform
distribution in a variety of spray patterns.
However, it is more complex and expensive because it requires compressed air. In most cases,
air atomizing nozzles are effective in locations where dust particles are extremely small and the
nozzles can be located in close proximity to the dust source, although some applications will
require large capacity air atomizing nozzles to throw their sprays long distances to reach the dust.
2.3.1 Chemical Additives to Control Droplets
Surfactants are sometimes used in wet spray applications because they lower the surface tension
of the water solution, which has the following effects: reduced droplet diameter; an increase in
the number of droplets for a given volume of water; and a decrease in the contact angle (Blazek
2003), defined as the angle at which a liquid meets a solid surface θ as shown bellow:-
Figure 8: Contact angle resulting from a liquid meeting a solid surface

28. 15
The use of surfactants increases the rate at which the droplets are able to wet or coat dust
particles; thus less moisture is used to produce the same effects as a typical water application.
Small amounts of surfactants can be injected into the spray water to improve the wetting and
subsequent control of dust particles (Swinderman et al. 2002).
Despite the effectiveness of chemical additives, it must be noted that they are not often used in
the metal/nonmetal mining industry based upon several limitations. Surfactants are significantly
more expensive than a typical water application. They can alter the properties of the mineral or
material being processed. They can damage some equipment such as conveyor belts.
The nozzle's droplet size distribution is the most important variable for proper dust control. The
droplet size decreases as the operating pressure increases. Information about the droplet size data
at various operating pressures can be obtained from the nozzle manufacturer. For wet dust
suppression systems, coarse droplets (200-500 µm) are recommended. For airborne dust capture
systems, very fine droplets (10-150 µm) may be required.
The fine droplets usually are generated by fogging nozzles, which may use either compressed air
or high-pressure water to atomize water in the desired droplet range. Droplet Velocity normally,
higher droplet velocities are desirable for both types of dust control through water sprays.
Information on the droplet velocity can be obtained from the nozzle manufacturer manual.
2.3.2 Wet Dust Suppression
There are two different types of wet dust suppressions: one wets the dust before it is airborne
(surface wetting) and the other wets the dust after it becomes airborne. At tanzanite one use dry
grinding which produce dusts to the environment especially around occupation area.
The Practical Resource for Cleaner, Safer, More Productive Dust & Material Control
(Swinderman et al. 2009), also devotes a chapter to the control of air movement, including a
section on effective measurement of air quantities. Finally, a recommended journal article is
"Dust Control System Design: Knowing your Exhaust Airflow Limitations and Keeping Dust out
of the System" (Johnson 2005).
Therefore in order to control the dust formed it is important to be aware of the fact that it should
not be automatically assumed that by wet, it means only water is being used in this process.

29. 16
From the British Occupational Hygiene Society (BOHS) Technical Committee studied the "dust
yield" defined as "the mass of aerosol produced per mass of powder dropped" (BOHS, 1998). It
shows that initially increasing the mass increases the dust yield, but a point is reached when the
dust produced per unit mass levels off and then decreases. From the book written by (Trivedi, S
M and Ajay, 2011) Dust suppression of mine can be applied during drilling and milling
processes may reduce dust emission.
Airborne Dust have confirmed this (Breum, 1999), and one concluded that "dust generation can
be minimized by having powders fall as large, discrete slugs instead of a stream of small clumps;
slugs should be as large as possible to minimize the exposure of the powder to the airflow. The
explanation is that with higher material flow, there is more material at the centre of the falling
mass, and this central part is less exposed to surrounding air, and hence less likely to disperse.
Figure 9: The use of water to suppress dust

30. 17
In many cases surfactants or chemical foams like Dustron PC are often added to the water into
these systems in order to improve performance. A water spray with surfactant lower the surface
tension of the water droplets and allow these droplets to spread further over the material and also
to allow deeper penetration into the material. Chemical foam is generally water and some sort of
special unify of surfactant.
Foam allows the surface area per unit volume of wetted material and efficiency of the
wetting to be increased. By applying this method during drilling and blasting processes may
reduce dust emission in surrounding working area. Wet drying is important and efficient method
to environment by eliminating dust emission during mining operation. Also the diagram bellow
gives details about the efficient of drop when surfactant is used:-
Figure 10: Sleap stream effect

31. 18
CHAPTER THREE
3.0 METHODOLOGY
3.1 Surveying and consultation on site (drilling and blasting)
Surveying on site conducted to look on the drilling, blasting techniques and to consult project
supervisor so as to obtain technical solutions of problems. It was done through the help of project
supervisor, environmentalists, mining engineers and various experts concerned with the issue, as
well as different environmental journals, internet and other related sources.
3.2. Dust data collection.
Dust collection systems are the most widely used engineering control technique employed by
mineral processing plants and underground mining activities to control dust and lower workers'
respirable dust exposure. A well integrated dust collection system has multiple benefits, resulting
in a dust-free environment that increases productivity and reclaims valuable product. Data
collected for the analysis of achieving the desired target, the data collected are compared with
standards where performed through of dust sampling apparatus. Test performed by making
comparison between the standards placed by national environmental management council
(NEMC-not to exceed 250mg/Nm3
) and world health organization (WHO-not exceed
500mg/Nm3
) (the dust that do not injure the heath of workers).
3.3 Dust sampling
Dust sampling is the method that used to determine dust emission at Tanzanite one. Dust
sampling is the method that used to determine dust emission at Tanzanite one. According to
American Conference of Governmental Industrial Hygienists [ACGIH 2010]. The ACGIH
handbook considered as a primary resource for anyone interested in protecting workers from dust
exposure in the mineral industry using dust collector systems, and especially for engineers who
are involved in designing such systems. Dust collector at the occupational area collects the dust
released daily. After every 5 days dust in the collector brought to the laboratory for analysis. By
knowing the type of dust emitted at the site will help in management of dust. The dust collection
system (local exhaust ventilation system) is one of the most effective ways to reduce dust
emissions. A typical dust collection system consists of four major components:

32. 19
Figure 11: Components of dust collection system
An exhaust hood used to capture dust emissions at the source, and Ductwork to transport the
captured dust to a dust collector, a dust collector remove the dust from the air, and fan and motor
provide the necessary exhaust volume and energy. Each of these components plays a vital role in
proper operation of a dust collection system, and poor performance of one component can reduce
the effectiveness of the other components. Therefore, careful design and selection of each
component is dangerous.
Principle of air flow
Airflows from a high- to a low-pressure zone due to the pressure difference; the quantity and the
velocity of airflow are related according to the following equation:
Q = AV
Where:
Q = volume of airflow, ft3
/min
(Note 1m = 3.28ft)
V = velocity of air, ft/min
A = cross-sectional area through which the air flows, ft2

33. 20
CHAPTER FOUR
4.0 DATA COLLECTION, ANALYSIS AND INTERPRETATION
4.1 Data Collection and Analysis
Table 1: Table show data of test # 1
Week 1, July 2014
Initial dust 210ppm and during the work 1095ppm
week 1 ORE PASS
Initial dust (ppm) 210
During the work (ppm) 1095
PH value in
pm
Days Dust weight (ppm)
Cumm
.
(ppm)
Cum
m. %
%
emission
2.5
1ST
3hours
2ND
3hours Total
Monday 527 485 1012 1012 21.14 78.86
Tuesday 457 381 838 1850 38.66 61.34
Wednesday 450 405 860 2710 56.63 43.37
Thursday 581 509 1090 3800 79.41 20.59
Friday 520 465 985
4785
100.0
0 00.00
Total weight of dust emission 2540 2245 4785

34. 21
Table 2: Table show data of test # 2
Week 2, July 2014
Initial dust 250ppm and during the work 1339ppm
week 2 LEVEL 73
Initial dust ppm 250
During the work ppm 1339
PH value in
pm
Days Dust weight (ppm)
Cumm.
(ppm)
Cumm.
%
%
emission
1ST
3hours
2ND
3hours Total
Monday 567 450 1017 1017 17.90 82.10
Tuesday 757 581 1338 2355 41.47 58.53
Wednesday 450 415 865 3220 56.70 43.30
2.5 Thursday 781 501 1282 4502 79.27 20.73
Friday 921 256 1177
5679
100.00 00.00
Total weight of dust emission 3476 2203 5679

35. 22
Table 3: Table show data of test # 3
Week 3, July 2014
Initial dust 245ppm and during the work 1400ppm
week 3 LEVEL 76
Initial dust (ppm) 245
During the work (ppm) 1400
PH value in
pm
Days Dust weight (ppm)
Cumm.
(ppm)
Cumm.
%
%
emission
1ST
3hours
2ND
3hours Total
Monday 811 550 1361 1361 25.90 74.10
2.5 Tuesday 634 421 1055 2416 45.99 54.01
Wednesday 564 615 1179 3595 68.44 31.56
Thursday 381 301 682 4277 81.42 18.58
Friday 620 356 976 5253 100.00 00.00
Total weight of dust emission 3010 2243 5253

36. 23
Table 4: Table show data of test # 4
Week 4, July 2014
Initial dust 295ppm and during the work 1600ppm
week 4 LEVEL 77/PILOT
Initial dust ppm 295
During the work ppm 1600
PH value in
pm
Days Dust weight (ppm)
Cumm.
(ppm)
Cumm.
%
%
emission
1ST
3hours
2ND
3hours Total
Monday 1012 450 1462 1462 19.26 80.74
2.5 Tuesday 931 628 1559 3021 39.79 60.21
Wednesday 888.1 600.5 1480.6 4501.6 59.29 40.71
Thursday 867 670.2 1537.2 6038.8 79.53 20.47
Friday 1001 553 1554 7592.8 100.00 00.00
Total weight of dust emission 4691.1 2901.7
7592.8

37. 24
4.2. Data Interpretation
THE GRAPH SHOWS RELATIONSHIP BETWEEN WEIGHT OF DUST EMISSION
AGAINST DAYS OF WEEK
ORE PASS
0
200
400
600
800
1000
1200
Monday Tuesday Wednesday Thursday Friday
D
U
S
T
C
O
N
C
.
(
P
P
M
)
DAYS
1ST 3hours
2ND 3hours
Total

38. 25
THE GRAPH SHOW RELATIONSHIP BETWEEN DUST EMISSION PER WEEK
LEVEL 73
0
200
400
600
800
1000
1200
1400
1600
Monday Tuesday Wednesday Thursday Friday
D
U
S
T
C
O
N
C
.
(
P
P
M
)
Days
1ST 3hours
2ND 3hours
Total

39. 26
THE GRAPH SHOW RELATIONSHIP BETWEEN DUST EMISSION PER WEEK
LEVEL 76
0
200
400
600
800
1000
1200
1400
1600
Monday Tuesday Wednesday Thursday Friday
D
U
S
T
C
O
N
C
.
(
P
P
M
)
Days
1ST 3hours
2ND 3hours
Total

40. 27
THE GRAPH SHOW RELATIONSHIP BETWEEN DUST EMISSION PER WEEK
LEVEL 77/PILOT
0
200
400
600
800
1000
1200
1400
1600
1800
Monday Tuesday Wednesday Thursday Friday
D
U
S
T
C
O
N
C
.
(
P
P
M
)
Days
1ST 3hours
2ND 3hours
Total

41. 28
CHAPTER FIVE
5.0 RESULTS AND DISCUSSION
From the data extracted from Tanzanite one mining company each table shows the initial and
final dust emission for both five days of the work, the model of the data collection is for every
three hours in order to avoid error and to make improvement of dust truck working efficient
during the data collection. The data summed together to find the total amount of dust emission
per day/week during the mining activities.
Lastly calculation of cumulative frequency and the percentage in order to know the exactly the
percentage of dust that will be reduced per day/week
Also from the data on the table and graphs shows variability of dust emission depending to
condition of ventilation and dust control technology, example from the ore pass dust emission is
very low compared to level 77/pilot since ore pass area is very near to the surface were
ventilation is actually fine compare to pilot were is very deeper about 1.5km from the surface.
(Total dust at ore pass 1095ppm while level 77/pilot 1600ppm) Furthermore, it seems that as the
ventilation decrease it results the high dust concentrate and therefore more technology required
for moderation.

42. 29
CHAPTER SIX
6.0 CONCLUSION AND RECOMMENDATION
6.1. Conclusion
Moderation of dust was done through the water suppression gives a least satisfactory of dust
emission due lack of enough technical methods like doing the magnification of spray equipments
and doing a sampling for analysis which will help to have a good follow up of dust on dealing
with performance of the sprayer.
6.2 Recommendation
Since it has been shown that there is increases in dust emission and the moderation conducted
through water suppression, I would like to recommend that the company might moderate much
by improve the suppression system by doing magnification of pipe nozzle depend to the size of
the dust particles (coarse droplets 200-500 µm and very fine droplets 10-150 µm may be
required). Also to use surfactant method of dust moderation (chemical foams like Dustron PC)
for the best result. By doing so the amount of dust emitted will be minimized in high extent and
to meet the standards 250mg/Nm3
- 500mg/Nm3
suggested by National Environmental
Management Council (NEMC) and World health organization (WHO).

43. 30
REFERENCES
 American Conference of Governmental Industrial Hygienists; “Industrial ventilation”, a
manual of recommended practice for design. 27th ed. Cincinnati, 2010.
 Bartell W, Jett B, “The technology of spraying for dust suppression”, Cement Americas,
pp. 32–37, 2005.
 Datson, H. Birch, W.J, “The development of a novel method for directional dust
monitoring”, Environmental Monitoring and Assessment, Vol.124 (1-3), pp.301-308,
2006.
 Trivedi, S .M, Ajay, Dust suppression of mine haul road, “India Seminars on Advances
in Mine Production and Safety”, Dhanbad, pp 239-246, 2011.
 Vallack, H. W. & Shillito, D. E , “Suggested guidelines for deposited ambient dust”,
Atmospheric Environment, Vol.32, pp.2737-2744, 1998.

44. 31
APPENDICES
Location of Tanzanite one mining company
Underground Drilling that results urge dust at Tanzanite one mining company

45. 32
Week 1, July 2014
Initial dust 210ppm and during the work 1095ppm
week 1 ORE PASS
Initial dust (ppm) 210
During the work (ppm) 1095
PH value in
pm
Days Dust weight (ppm)
Cumm.
(ppm)
Cumm
. %
%
emission
2.5
1ST
3hours
2ND
3hours Total
Monday 527 485 1012 1012 21.14 78.86
Tuesday 457 381 838 1850 38.66 61.34
Wednesday 450 405 860 2710 56.63 43.37
Thursday 581 509 1090 3800 79.41 20.59
Friday 520 465 985 4785 100.00 00.00
Total weight of dust emission 2540 2245 4785

46. 33
Week 2, July 2014 : Initial dust 250ppm and during the work 1339ppm
week 2 LEVEL 73
Initial dust ppm 250
During the work ppm 1339
PH value in
pm
Days Dust weight (ppm)
Cumm.
(ppm)
Cumm.
%
%
emission
1ST
3hours
2ND
3hours Total
Monday 567 450 1017 1017 17.90 82.10
Tuesday 757 581 1338 2355 41.47 58.53
Wednesday 450 415 865 3220 56.70 43.30
2.5 Thursday 781 501 1282 4502 79.27 20.73
Friday 921 256 1177
5679
100.00 00.00
Total weight of dust emission 3476 2203 5679
Week 3, July 2014: Initial dust 245ppm and during the work 1400ppm
week 3 LEVEL 76
Initial dust (ppm) 245
During the work (ppm) 1400
PH value in
pm
Days Dust weight (ppm)
Cumm.
(ppm)
Cumm.
%
%
emission
1ST
3hours
2ND
3hours Total
Monday 811 550 1361 1361 25.90 74.10
2.5 Tuesday 634 421 1055 2416 45.99 54.01
Wednesday 564 615 1179 3595 68.44 31.56
Thursday 381 301 682 4277 81.42 18.58
Friday 620 356 976 5253 100.00 00.00
Total weight of dust emission 3010 2243 5253

47. 34
Week 4, July 2014: Initial dust 295ppm and during the work 1600ppm
week 4 LEVEL 77/PILOT
Initial dust ppm 295
During the work ppm 1600
PH value in
pm
Days Dust weight (ppm)
Cumm.
(ppm)
Cumm.
%
%
emission
1ST
3hours
2ND
3hours Total
Monday 1012 450 1462 1462 19.26 80.74
2.5 Tuesday 931 628 1559 3021 39.79 60.21
Wednesday 888.1 600.5 1480.6 4501.6 59.29 40.71
Thursday 867 670.2 1537.2 6038.8 79.53 20.47
Friday 1001 553 1554 7592.8 100.00 00.00
Total weight of dust emission 4691.1 2901.7
7592.8
THE GRAPH SHOW RELATIONSHIP BETWEEN DUST EMISSION PER WEEK
ORE PASS:
0
200
400
600
800
1000
1200
Monday Tuesday Wednesday Thursday Friday
D
u
s
t
c
o
n
.
(
p
p
m
)
Day
1ST 3hours
2ND 3hours
Total

48. 35
THE GRAPH SHOW RELATIONSHIP BETWEEN DUST EMISSION PER WEEK
LEVEL 76
THE GRAPH SHOW RELATIONSHIP BETWEEN DUST EMISSION PER WEEK
LEVEL 77/PILOT
0
200
400
600
800
1000
1200
1400
1600
Monday Tuesday Wednesday Thursday Friday
D
U
S
T
C
O
N
C
.
(
P
P
M
)
Days
1ST 3hours
2ND 3hours
Total
0
200
400
600
800
1000
1200
1400
1600
1800
Monday Tuesday Wednesday Thursday Friday
D
U
S
T
C
O
N
C
.
(
P
P
M
)
Days
1ST 3hours
2ND 3hours
Total

49. 36
Formula
CALCULATION
Cumulative Weight of dust per week = weight1, (weight 1+weight 2), (weight 1+weight 2
+weight 3)
For example
Table no.4
1462+1559+1480.6+1537.2
% cumulative weight= (cumulative weight/total weight) *100%
For example
(1462/7592.8)*100%
=19.26%
(1559/7592.8)*100%
=20.5%
%of dust emission/day =100 - % cumulative weight retained
100-19.26%
=80.74%
Therefore the dust emission per week can be reduced/ controlled for more than 80.00%