evaluation and planning of beach mining at pantai pasir hitam

SCHOOL OF MATERIALS AND MINERAL RESOURCES ENGINEERING UNIVERSITI SAINS MALAYSIA

EVALUATION AND PLANNING OF BEACH MINING AT PANTAI PASIR

HITAM, LANGKAWI

By

MUHAMMAD ZULQAYYIM BIN NOOR AZIZUL

Supervisor: Assoc. Prof. Dr.Hashim Bin Hussin

Dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Engineering with Honours

(Mineral Resources Engineering)

Universiti Sains Malaysia

JULY 2013

ii

DECLARATION

I hereby declare that I have conducted, completed the research work and written the

dissertation entitled “Evaluation and Design of Beach Mining in Pantai Pasir Hitam,

Langkawi”. I also declare that it has not been previously submitted for the award of any

degree or diploma or other similar title of this for any other examining body or

University.

Name of Student: MUHAMMAD ZULQAYYIM BIN NOOR AZIZUL

Signature:

Date:

Witness by,

Supervisor: ASSOC. PROF. DR. HASHIM BIN HUSSIN

Signature:

Date:

iii

ACKNOWLEDGEMENTS

Alhamdulillah, thank to Allah SWT as I had successfully completed my Final

Year Project. The report presented here consists of knowledge and experience that I

have gain and have been through in completing my Final Year Project. First and

foremost, I would like to express my appreciation to my beloved family, my lovely

parents, Noor Azizul Bin Ibrahin and Noreha Binti Omar for always giving their full

support on me throughout my life.

Next, I would like to give my heartiest gratitude to my supervisor, Assoc. Prof.

Dr.Hashim Bin Hussin for his guidance while I am conducting the experiments and the

help his gave since day one. Thank you to my friends and coursemates especially

Muhammad Azlan Bin Ishak who have shared their wisdom with me and providing me

with helps and support. I would like to express my thanks to all of my Mineral

Resources Engineering lecturers who have tough me the knowledge that have helped me

throughout this research.

Not forgetting all the dedicated technicians who provide me with their technical

help and millions of thanks especially to Pn. Hasliza, En. Kemuridaan, En. Saarani, En.

Khairi and Cik Mahani for all the assistance and sacrifice of time and energy in helping

me to complete this project. Last but not least, I would like to thank those which I might

unintentionally left out in expressing my gratitude. Thank you again everyone, either

direct or indirectly involved in helping me in completing this thesis.

iv

TABLE OF CONTENTS

TOPIC PAGE

DECLARATION ii

ACKNOWLEDGEMENT iii

TABLE OF CONTENTS iv

LIST OF TABLES vii

LIST OF FIGURES viii

LIST OF PLATES xi

LIST OF ABBREVIATION xii

ABSTRAK xiii

ABSTACT xiv

CHAPTER 1 INTRODUCTION

1.1 Introduction 1

1.2 Significant of Project 2

1.3 Problem Statement 3

1.4 Objective 4

1.5 Location of Study Area 4

1.6 Scope of Work 7

CHAPTER 2 LITERATURE REVIEW

2.1 Geology 8

2.2 Heavy Mineral Sands 9

2.3 Strip Mining 11

2.4 Type of Placer Deposit 12

2.4.1 Beach Placers 12

2.4.2 Residual Placers 12

2.4.3 Eluvial Placers 13

2.4.4 Stream of River Placers 13

2.4.5 Riverbank and Flood Placers 13

v

2.4.6 Aeolian Placers 14

2.5 Formation of Beach Placer Deposits 14

2.6 Factors Controlling Formation of Beach Placer Deposit 15

2.7 Littoral Transportation 16

2.8 Waves 17

2.9 Tides 18

2.9.1 Types of Tide 19

2.9.2 Spring Tide and Neap Tide 20

2.10 Currents 22

2.10.1 Rip Currents 22

2.10.2 Density Currents 23

2.10.3 Longshore Currents 23

2.10.4 Currents of Mass Transport 23

2.11 Wind 24

CHAPTER 3 RESEARCH METHODOLOGY

3.1 Introduction 25

3.2 Literature Investigation 29

3.2.1 Geological Study 29

3.2.2 Tide Analysis 30

3.3 Site Study 32

3.3.1 Area Determination 32

3.3.2 Marking Out 33

3.3.3 Stripping 35

3.3.4 Sampling Activities 37

3.3.5 Rate of Redistribution Analysis 38

3.4 Experimental Analysis 39

3.4.1 Evaluation of Heavy Minerals 39

3.4.1.1 Mozley Table 41

3.4.2 Mineral Identification 42

vi !

3.4.2.1 Magnetic Separator 44

3.4.2.2 Electrostatic (High-Tension) Separator 44

3.4.2.3 Optical Microscope 45

3.4.2.4 Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM- EDX)

46

3.4.2.5 X-ray Fluorescence (XRF) Analysis 46

CHAPTER 4 RESULT AND DISCUSSION

4.1 Introduction 48

4.2 Site Study 48

4.3 Rate of Redistribution Analysis 51

4.3.1 Day First (24.01.13) 52

4.3.2 Day Second (25.01.13) 54

4.3.3 Day Third (26.01.13) 56

4.3.4 Day Fourth (27.01.13) 58

4.3.5 Day Fifth (28.01.13) – Last Day 60

4.4 Evaluation of Heavy Minerals 64

4.5 Minerals Identification by Optical Microscope 68

4.6 Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDX) Analysis

71

4.7 X-Ray Fluorescence (XRF) Analysis 78

CHAPTER 5 CONCLUSION AND RECOMMENDATIONS

5.1 Conclusion 82

5.2 Recommendation 84

REFERENCES 85

APPENDIX A 88

APPENDIX B 91

APPENDIX C 94

APPENDIX D 94

vii

LIST OF TABLE

TABLES PAGE

Table 2.1

Common Mineral Sands, Their Physical Properties and Chemistry

10

Table 4.1 Simplified Data of Beach Placer Deposits Levels 61

Table 4.2 Overall Increments of Beach Placer Deposits 62

Table 4.3 Summarized Data of Heavy Mineral Concentration in Beach Placer Deposits 67

Table 4.4

Minerals Form Magnetic Particles After Separated Using HTS

71

Table 4.5

Minerals Form Non-Magnetic Particles After Separated Using HTS

72

Table 4.6

X-Ray Fluorescence (XRF) Analysis for Raw Sample of Black Sand.

81

viii

LIST OF FIGURES

FIGURES PAGE

Figure 1.1

Map of Langkawi Island and The Location of Pantai Pasir Hitam (Marked A) From Satellite View (Google Earth)

5

Figure 1.2

Detail Location of Pantai Pasir Hitam (Marked A) Area Including Picture of The Study Area (Google Maps) 6

Figure 2.1 General Geologic Maps of Langkawi Island 8

Figure 2.2 Stripping Mining Techniques 11

Figure 2.3

Typical Beach Pattern With Offshore Bars. Mineral Accumulations Have Formed Placer Deposits in Dunal System

15

Figure 2.4 Littoral Transport of Sediment Along The Shore 16

Figure 2.5

Typical Oscillation Waves With Orbiting Water Particles Slowly Moving In Direction of Waves Movement

18

Figure 2.6 Types of Tides and Their Distribution 19

Figure 2.7

Combination of Lunar and Solar Equilibrium Tides to Produce Spring Tides at New and Full Moon and Neap Tides at First and Last Quarter of Moon Phase

21

Figure 2.8 Tide Phases and Moon Phases 21

Figure 2.9

Rip Current Formations at Lowest Point of an Offshore Bar

22

Figure 3.1 The Flowchart Of Research Work 27

Figure 3.2 General Geologic Maps of Langkawi Island 29

Figure 3.3

Sea Level at Langkawi Station on 8th To 15th January 2013

30

Figure 3.4


31

Figure 3.5


31

Figure 3.6

Sea Level at Langkawi Station on 29th January To 5th February 2013

31

ix

Figure 3.7 Illustration of Sampling Point at Study Area 34

Figure 3.8 Detail Flowchart for Heavy Minerals Evaluation 40

Figure 3.9 Detail Flowchart for Mineral Identifications 43

Figure 4.1

New Beach Placer Level on 24.01.13 After First Stripping

52

Figure 4.2 Data of Beach Placer Level on 24.01.13 at Evening 53

Figure 4.3 Data of Beach Placer Level on 25.01.13 at Morning 54







Figure 4.10 Illustration of Sampling Point at Study Area 65

Figure 4.11 Relation Between Beach Increments And Heavy Minerals Concentration In Black Sand Deposit. 68

Figure 4.12 Magnetic and Conductor 71

Figure 4.13 Magnetic and Non-Conductor 71

Figure 4.14 Non-Magnetic and Conductor 72

Figure 4.15 Non-Magnetic and Non-Conductor 72

Figure 4.16

SEM Images of Raw Black Sand at 50 Times Magnification

73

Figure 4.17

SEM Images of Raw Black Sand at 50 Times Magnification

73

Figure 4.18

SEM Photomicrograph of Raw Black Sand Deposit Sample

74

Figure 4.19

EDX Diffractogram Showing The Presence of Hematite in Figure 4.18.

75

Figure 4.20

EDX Diffractogram Showing The Presence of Zircon in Figure 4.18.

75

x

Figure 4.21

EDX Diffractogram Showing The Presence of Quartz With Some Clay Impurities in Figure 4.18.

76

Figure 4.22

SEM Photomicrograph of Raw Black Sand Deposit Sample (Different Location).

76

Figure 4.23

EDX Diffractogram Showing The Presence of Ilmenite (Light Structure) in Figure 4.22.

77

Figure 4.24

EDX Diffractogram Showing The Presence of Quartz (Dark Spot) in Figure 4.22.

77

Figure 4.25


78

Figure 4.26

EDX Diffractogram Showing The Presence of Hematite (Light Colour) in Figure 4.25.

78

Figure 4.27

EDX Diffractogram Showing The Presence of Quartz (Grey Colour) in Figure 4.25

79

Figure 4.28


79

Figure 4.29

EDX Diffractogram Showing The Presence of Tourmaline in Figure 4.28.

80

xi

LIST OF PLATES

PLATES PAGE

Plate 3.1 Study Area (Red Box) at Pantai Pasir Hitam, Langkawi 33

Plate 3.2

Sampling Point at Study Area and The Marks on Each Stakes as Indicator to Determine The Level of Black Sands Deposit

34

Plate 3.3

Method of Strip Mining for Evaluation of Black Sands Deposit

36

Plate 3.4

Method of Strip Mining for Evaluation of Black Sands Deposit

36

Plate 3.5

Soil Shovel Used for Stripping and Sampling of Black Sands Deposit

37

Plate 4.1

Heavy Mineral Deposit Near The Banks Along The Beach Area

49

Plate 4.2

Distribution of Heavy Minerals Along The Shoreline and Under The Sea

50

Plate 4.3 Source of The Heavy Mineral Deposit 50

Plate 4.4 Burrows Made by Crabs 51

Plate 4.5 Sea Level was Raising During Stripping is Done 53

Plate 4.6 Site Area on 25.01.13 at Evening 55

Plate 4.7 Presence of Barrier or Sea Walls at The Sea Area. 64

xii

LIST OF ABBREVIATION

ABBREVIATION

SEM Scanning Electron Microscopy

EDX Energy Dispersive X-Ray Spectroscopy

XRF X-Ray Fluorescence

JMG Minerals and Geosciences Department

JMM Malaysian Meteorological Department

HIMS High Intensity Magnetic Separator

LIMS Low Intensity Magnetic Separator

xiii

PENILAIAN DAN REKABENTUK PERLOMBONGAN PANTAI DI PANTAI PASIR HITAM, LANGKAWI

ABSTRAK

Satu kajian awal telah dijalankan keatas deposit pasir hitam yang terletak di

Pantai Pasir Hitam, Langkawi, Kedah. Kajian ini menggunakan konsep perlombongan

‘strip mining’ untuk menilai kenaikan paras pantai dan kepekatan mineral berat dalam

deposit pasir hitam selepas disebarkan oleh ombak. Kawasan yang dikorek ditinggalkan

selama tempoh tertentu untuk membolehkan ombak menyebarkan semula deposit pasir

hitam. Kajian menunjukkan bahawa kenaikan purata deposit pasir hitam adalah 0.8 inci

jika deposit pasir hitam dikorek sebelum air pasang. Namun, kenaikan purata deposit

pasir hitam apabila pantai tidak dikorek adalah sekitar 0.1 inci sahaja. Kepekatan purata

mineral berat yang menggantikan deposit yang telah dikorek adalah 41% selepas setiap

kali air pasang dan 42% pada setiap titik persampelan. Pemerhatian ke atas ciri-ciri

topografi di sekitar kawasan tapak telah dilakukan untuk menentukan asal-usul deposit

pasir hitam. Daripada pemerhatian yang dilakukan, deposit pasir hitam sebenarnya

datang dari laut hasil daripada kesan ombak. Ini kerana, tidak ada kesan mineral pasir

hitam yang dapat dilihat dari tebing berhampiran dengan kawasan pantai. Sampel asal

deposit pasir hitam juga dianalisis di bawah mikroskop optik dan SEM-EDX dan

menunjukkan kehadiran ilmenit, bijih besi, pirit, rutil, zirkon, turmalin, monazit dan

kuarza dalam deposit pasir hitam.

xiv

EVALUATION AND DESIGN OF BEACH MINING IN PANTAI PASIR HITAM, LANGKAWI

ABSTRACT

A preliminary study was conducted on black sands deposit which is located at

Pantai Pasir Hitam, Langkawi, Kedah. The study utilize the concept of strip mining to

evaluate new beach level and concentration of heavy mineral in black sand deposit after

redistributed by wave effect. The stripping area was left for certain period to allow tide

effect to redistribute the black sand deposit. The results show that the average

increments of black sand deposit are 0.8 inches if the black sand deposits are stripped

before high tide. While, the average increments of black sand deposit when stripping is

not done is around 0.1 inches only. The average concentration of heavy mineral that

replaced the stripped deposit after redistribution is 41% at particular tides and 42% at

each particular sampling point. Observation on topographical features around the site

area was done to determine the origin of black sand deposit. From the observation, the

black sand deposits are actually coming from the sea by the wave action because there

are no traces of black sand minerals from the banks near the beach area. Raw sample of

black sand deposit was also analysed under optical microscope and SEM-EDX showing

the presence of ilmenite, hematite, pyrite, rutile, zircon, tourmaline, monazite and quartz

in the black sand deposit.

1 !

CHAPTER 1

INTRODUCTION

1.1 1ntroduction

Black sands are normally refers to concentration of heavy minerals in an alluvial

environment such as beach or river system. Sometimes these deposits are referred to as

‘beach sand’. Black sands are placer deposits that mostly formed in beach environment.

This type of deposit is formed when the mechanical and chemical breakdown of rock

masses followed by a redistribution of the mineral along the shoreline (Jones G. 2008).

Black sands contain a number of minerals with high specific gravity known as

‘heavy mineral’. Usually, minerals with specific gravity above 4.2 g/cm3 can be

considered as heavy minerals. Heavy mineral sands are a class of ore deposits which

include economically important minerals such as rutile (TiO2), ilmenite (FeTiO3),

zircon (ZrSiO4) leucoxene (Fe.TiO3.TiO2) and others. Rutile and leucoxene are

alteration product of ilmenite which are titanium dioxide based mineral. Other minor

minerals that may be found associate with mineral sands comprise monazite, magnetite,

garnet, xenotime, precious metals, gemstones or rare earth elements (Jones G. 2008).

According to Geoscience Department Australia (2012), Australia is the leading

producer of mineral sand in the world today. Black sands also have been found in many

countries such as South and South-East Asia. Some of them are being produce from

beaches in Sri Lanka, India, Indonesia (Tyler R.M. et al. 2004).

2 !

According to Geoscience Department Australia (2012) and the United States

Geological Survey data in (2011), the world’s leading producer of rutile and zircon is

Australia. It also represents the world’s largest economic resources in 2011 with 53%,

and 50%, respectively. Australia also has the second largest share of the world’s

ilmenite with 15%, behind China, which has 31%. Other major country rankings

include India (13%), South Africa (10%) and Brazil (7%) for ilmenite, South Africa

(16%) and India (14%) for rutile and South Africa (23%) and Ukraine (7%) for zircon.

1.2 Significant of Project

Systematic prospecting and exploration method must go before further

investment for acquisition, development and exploitation to estimate the value of any

deposit. This research project is focused on preliminary study of black sands deposit

which include evaluation and design of beach mining in Pantai Pasir Hitam, Langkawi,

Kedah. The evaluation black sands deposit is important to determine the grade of heavy

mineral and mineral distribution along beach shoreline.

In this study, strip mining is utilized to excavate the black sands deposit.

However, it is important to know the rate of the deposit to recover back to the original

level and the concentration of heavy mineral that replaced after the deposit is excavated.

This study on the black sands deposit will provide an important data on the formation

and composition of the heavy minerals presence in the deposit after being mined.

3 !

1.3 Problem Statement

In general, this project is to understand the formation of black sands deposit

along a beach front. Since there is no previous research about beach mining in Malaysia,

this research is conducted to get some data of black sands deposit in Pantai Pasir Hitam

area. The origin of the black sands deposit need to be study to identify whether it comes

from the sea by wave and tidal effect or the accumulation of black sands deposit

because of weathering process from rock masses.

Stripping mining method concept is utilized in this project to excavate the

deposit. However, it is important to know the new level of deposit that recover back the

excavated black sand from the original level and the composition of heavy mineral with

the new deposit. This is done to estimate the effect of wave to the increment of beach

level and amount of heavy mineral in the deposit.

According to article impact of sand mining by The Anguilla National Trust,

unregulated removal of beach sand has had a huge impact on beach area. For example,

sand dunes that once loomed over the beach and protected the inland shoreline and

vegetation have been reduced to a three-foot mound that is being eroded by constant

wave action and a continued sand mining effort. Therefore, it is necessary to make sure

this method is possible to maintain the nature of the beach.

4 !

1.4 Objective

The objectives of the research are as follows:

1. To identify the origin of black sand deposit that formed along the shoreline of

Pantai Pasir Hitam beach.

2. To determine the new level of black sand deposit after redistributed to recover

back the excavated black sands deposit.

3. To determine the concentration of heavy mineral that replaced the excavated

black sands deposit.

1.5 Location of Study Area

The location of the study area in this research project is along the shoreline of

Pantai Pasir Hitam, Langkawi Kedah. This beach is located at the north region of

Langkawi Island and about 2 km west of Tanjung Rhu Beach, Langkawi. Figure 1.1

shows the map of Langkawi Island and the location of Pantai Pasir Hitam from satellite

view (Google Earth). Figure 1.2 shows the more detail location of Pantai Pasir Hitam

area including picture of the study area (Google Maps)

5

Figure 1.1: Map of Langkawi Island and the location of Pantai Pasir Hitam (marked A) from satellite view (Google Earth).

6

Figure 1.2: Detail location of Pantai Pasir Hitam (marked A) area including picture of the study area (Google Maps).

7

1.6 Scope of Work

Field study is carried out during semester break on 24th to 28th January 2013

after acquiring the permission from Minerals and Geosciences Department (JMG)

Kedah. Data form “Sea Level Monitoring Activity” in Langkawi, Kedah have shown

that the tides from 24th to 28th January 2013 is moving from the low tide to the high tide.

The tide height is 1.5 m on 24th and gradually increases to 2.5 m on 28th which are very

preferable to conduct this study.

During field work, stripping which is almost similar to a concept of strip mining

was done at the site area to evaluate the black sand deposit. The evaluation is done to

know the increment of beach level after redistribution of black sand deposit due to the

tide effect. Sample of black sands deposit were taken to determine the heavy mineral

concentration in black sands deposit. Data obtained from the study were analysed and

tabulated.

8

CHAPTER 2

LITERATURE REVIEW

2.1 Geology

Langkawi Island comprises the oldest rocks and the most complete Palaeozoic –

Mesozoic sequence of sedimentary formations (Komoo I.). However, based on the

research made by Geological Survey of Malaysia in 1985, geology of Langkawi island

can be further divided to 6 types of rocks according to their geological age shown in

Figure 2.1. Based on that research, Pantai Pasir Hitam is actually located around the

area of Triassic granite formation of rock.

Figure 2.1: General geologic maps of Langkawi Island (Geological Survey

Malaysia 2013).

9

The shoreline of Pantai Pasir Hitam is composed of sand which is not

completely black, but it is actually like a mixture of black sand and normal sand.

However, like other black sand beaches, the sand is not volcanic in nature. It is actually

a mixture of sand and variety of heavy mineral sand (Voyage 2010).

2.2 Heavy Mineral Sands

Mineral sands are black sands deposit that mostly formed in beach

environments. According to Department of Environment and Primary Industries on Mar

2012, these minerals are formed from variety of igneous and metamorphic rock, but

being physically and chemically resistant to weathering. Heavy minerals are a term for

minerals that have specific gravity greater than quartz which are 2.7 g/cm3 (Reyneke L.

et al., 2001). Heavy mineral sands contain a number of mineral with high specific

gravity which is usually higher than 4.2 g/cm3 (Reyneke L. et al., 2001).

Concentration of heavy mineral is resulted from the normal cycle of erosion.

The economic black sands deposit is formed when rock material has generated

sufficient quantities of valuable mineral. When suitable geography and climate

condition is provided to transport the heavy mineral, they tend to accumulate in river

channels and along coastline (Macdonald E.H. 1973).

Most of the rock forming mineral is fragmented and altered during the erosion

cycle by combination of physical and chemical actions. But only the stable minerals

survive. These minerals are quartz, garnet, ilmenite, leucoxene, rutile, zircon, monazite,

gold, cassiterite and variety of gemstone (Macdonald E.H. 1973). Common mineral

sands with their physical properties and chemistry are shown in table below.

10

Table 2.1: Common mineral sands, their physical properties and chemistry (Jones G.

2008).

Mineral Valuable Magnetic Susceptibility

Electrical Conductivity

Specific Gravity

Chemical Formula

Ilmenite Yes High High 4.5 – 5.0 Fe.TiO3

Rutile Yes Low High 4.2 – 4.3 TiO2

Zircon Yes Low Low 4.7 ZrSiO4

Leucoxene Yes Semi High 3.5 – 4.1 Fe.TiO3.TiO2

Monazite No Semi Low 4.9 – 5.3 (Ce,La,Th,Nd,Y)PO4

Staurolite No Semi Low 3.6 – 3.8 Fe2Al9Si4O22.(OH)2

Kyanite No Low Low 3.6 – 3.7 Al2SiO5

Garnet No Semi Low 2.4 – 4.2 (Fe,Mn,Ca)3.Al2(SiO4)3

Quartz No Low Low 2.7 SiO2

Emery and Noakes (1968) have suggested that the practical division of valuable

heavy minerals to three sections. The first are ‘heavy heavy’ minerals which composed

of gold, platinum and cassiterite. These minerals having SG above 6.8 and occur

principally in stream beds and less than 15 km from their sources. Second are ‘light

heavy’ minerals which composed of rutile, zircon, ilmenite, magnetite, monazite and

gemstone (diamond, sapphires, etc.) (Sekhar, L.K et al., Dec 2003). These minerals

having SG between 4.2 to 5.3 which are widespread and can be found at considerable

distance from their sources. Third are ‘light heavy minerals’ which composed of silica,

quartz, etc. This group have specific gravity between 2.7 to 4.2 and may also be found

at considerable distance from their sources (Gupta H.K., 2005).

11

2.3 Strip Mining

Strip mining is one types of surface mining methods used mainly for mining a

seam of mineral such as coal and other bedded deposit. In strip mining, overburden is

not transported to waste dump for disposal. However, the overburden is being cast

directly into adjacent mined out panels. Materials handling in strip mining consist of

excavation and casting that are generally combined in one unit operation and being

conducted by using a single machine as shown in Figure 2.2 (Surface mining, May

2013).

Figure 2.2: Stripping mining techniques (Strip mining, April 2013).

The concept of strip mining methods was used to mine the beach placer deposit

in this study. The mining process proposed in this study is actually from the concept of

strip mining, but being modified to be compatible with the mining area. At first,

stripping is done to excavate the beach placer deposit. The beach placer was stripped for

12

several depths to obtain the heavy minerals. However, the stripped beach placer is not

being dump into the adjacent area, but being transferred to processing plant to obtain the

heavy mineral concentrate.

After few days, the excavated area is refilled with new black sands deposit that

being distributed during high tide. Stripping is done after the refilled placers deposits

have reach the original black sands deposit levels. The strip mining methods are done

step by step to reduce the impact to the surrounding environment and also the beach

itself.

2.4 Type of Placer Deposit

Placer deposits can be classified into several types depending on the location of

formation of the deposit. The major types include residual placers, eluvial placers,

stream or river placers, riverbank and flood placers, aeolian placers, and beach placers

(Coyne M.S et al., April 1998).

2.4.1 Beach Placers

Beach placers are generally formed by the combined effects of chemical and

mechanical breakdown of rock masses. They also redistributed along the shore by the

action of tides, wind, currents and storm waves (Coyne M.S et al., April 1998).

2.4.2 Residual Placers

Residual placer deposit will occur near to the breakage of original source rocks.

Residual placer will undergo some degree of enrichment of the placer minerals by

elimination of non-valuable minerals by weathering process (Coyne M.S et al., April

1998).

13

2.4.3 Eluvial Placers

Eluvial placers represent the transitional stage between residual placers and

stream or river placers. Eluvial placers usually come from high level environment which

then transported downslope from the source rocks. But, the valuable minerals have not

yet move to streams and rivers that would transport them to other places (Coyne M.S et

al., April 1998).

2.4.4 Stream or River Placers

Stream or river placers are the most widespread and well known type of placers.

This type of placers made up of a mixture of poorly sorted rock fragments and minerals

from the adjacent hillside. Because of the steep gradient, running water especially

where there is turbulence will effectively sort the rock fragments and minerals

according to its size and density. Higher density minerals will settle out and trapped in

gaps and irregularities on the stream beds. The lower density mineral will be wash away

with the water stream (Coyne M.S et al., April 1998).

2.4.5 Riverbank and Flood Placers

Riverbank and flood placer are deposit adjacent to streams and rivers. The

deposit may be left along the bank of the river as the rivers meander, cut downward or

overflow their banks in flood condition (Coyne M.S et al., April 1998). As a stream

flows around a curve, tangential forces formed which cause an increase in velocity at

the outer radius of the river bank and decrease in velocity along the inside radius. Water

layer on the bottom part is retarded by friction and resulted to flow sideways along the

bottom toward the inner bank (Bureau of Land Management, 2011).

14

Valuable placer deposits may be settled in the river bank sediments that are

adjacent to the present rivers. Flood placers also occur in the sediments adjacent to

rivers. They form continuously during flooding when water flow is sufficient to

transport valued placer mineral up and out of the channels. As the water velocity

decreases, the placer mineral are left as placer deposits along the adjacent floodplains

(Coyne M.S et al., April 1998).

2.4.6 Aeolian Placers

Aeolian placers are formed when large parts of beach sand are exposed to the

wind action. High wind removed lighter mineral and therefore, enriched the heavy

minerals content. Aeolian placers are usually occur in the desert regions (Coyne M.S et

al., April 1998).

2.5 Formation of Beach Placer Deposits

Beach placers are generally formed because of the breakdown of rock masses by

chemical and physical action. The break rock masses are then redistributed along the

continental shoreline as shown in Figure 2.3 (Macdonald E.H. 1973). Beach placers are

then distribute by the action of tides and storm waves along beaches. The flow of the

waves and the generation of longshore currents, especially under storm conditions, can

effectively sort beach materials (Coyne M.S et al., April 1998).

The movement of the sea gradually sort the sediments according to their size and

particle properties, strength and direction of wind and ocean currents. The finer

materials will go into deep water and the coarser to the shore. The valuable minerals

usually become concentrated with the coarser grained sediments along the shore.

(Macdonald E.H. 1973).

15

Figure 2.3: Typical beach pattern with offshore bars. Mineral accumulations have

formed placer deposits in dunal system (Macdonald E.H. 1973).

2.6 Factors Controlling Formation of Beach Placer Deposit

Kumar A. (May 2011) stated that the formations of beach placers are the effect

from the geological and geomorphological. Geological and geomorphological factors

that controlling the concentration of heavy minerals formation along beach coast area

are as follows:

Geological controls: The type of parent rocks such as igneous, metamorphic or

sedimentary rock and geological processes have contributed important factors

to a formation of placer deposit. Topography and location of the area, the

duration of erosion cycle and area of source rocks exposed to erosion also play

an important role towards the formation of placer deposit.

Climate factors: Climate condition can control the decomposing and

breakdown of the rocks and mineral fragments that get liberated from the

source rock. In tropical to sub-tropical climate, deep chemical weathering

promotes the formation of laterites.

16

Drainage Pattern: The formation of new or young river and their high density

material may supply the valuable minerals along the favourable area.

Coastal Processes: Littoral transport, sorting and deposition of placer minerals

may affected by wave velocity, long shore currents, wind speed, tidal effect,

and also direction and strength of currents. Emergence and submergence of

coast base on geological history also affects the beach placer formation.

2.7 Littoral Transportation

The transportation of sedimentary particles along the continental shelf formed

when waves strikes the beach at an angle. Sedimentary particle is also transported along

the shore in a zigzag pattern by waves rushing onto the beach as shown in Figure 2.4.

The movement of sedimentary particle may be in slipping and rolling motion by the

action of waves (Rittenhouse G. 1943).

Figure 2.4: Littoral transport of sediment along the shore (Woods Hole Group, 2011).

17

In simplest case, the forces by sea water movement acting on a single particle

can be resolves into two components which are 1 - drag force in the direction of flow

and 2 - lift force which are normal to the direction of flow. As motion occur in the

direction of the lift force, the particle will then uplifted and creating nearly zero

frictional force causing the particle free to move (Macdonald E.H. 1973). The

sedimentary particles moves up the beach at the angle of wave direction and backwash

of wave moves the particles back to the beach due to gravity influence (Longshore drift,

2013).

2.8 Waves

Water waves are generated when any form of energy is applied to a water body.

Waves are formed when there is a change in atmospheric pressure that may raising and

lowering the surface of water. Wind that blow on the surface of water or wind generated

waves create ripples which subsequently grow to waves as the wind blow faster to the

water body. Water waves may also formed by earthquakes or landslides (Macdonald

E.H. 1973).

Water particle moved with a little forward motion to the shore. However, the

particle is actually oscillate in almost circular orbits and travel in the direction of waves.

The orbit size and shape change to smaller radius with increase in depth as shown in

Figure 2.5 (Macdonald E.H. 1973).

18

Figure 2.5: Typical oscillation waves with orbiting water particles slowly moving in

direction of wave movement (Macdonald E.H. 1973).

At the shallower region, potential energy will abruptly release causing

transformation of oscillation waves to translation waves. During big storms, high speed

winds provide additional energy to these waves thus forming a beach placers from

material that trapped by oscillation waves (Macdonald E.H. 1973).

2.9 Tides

Gravitational forces exerted by the sun and moon on the earth, moon altitude

above the earth equator and rotation of the earth create an effect of rise and fall of sea

levels called high tides and low tides. The variation in those factors cause height of the

tide varies from day to day but the fluctuations are predictable. Gravitational pull by sun

is actually stronger than moon gravitational pull. However, gravitational forces that

created by sun that affect tides much weaker than the moon as the moon located a lot

closer than the sun (Boatsafe, 2009).

19

2.9.1 Types of Tide

Some part of the earth may experience only two tides a day and some part may

experience four times a day. There are three types of tide which are 1 – Diurnal tide; 2 -

Semi-Diurnal tide and 3 – Mixed tide (Tide, 2013).

Figure 2.6: Types of tides and their distribution (Tide, 2013).

As shown in Figure 2.6, the most common are semi-diurnal tide which

experiences two high and two low tides a day and diurnal type of tide which

experiences one high tide and low tide a day. Mixed tide are almost the same with

20

semi–diurnal tides but the two high tides having significant difference level. Same goes

to the two low tides levels. The daily difference of tide levels are not consistence

because of the location of moon which create different gravitational forces to the water

(Tide, 2013).

Malaysia is one of the parts that experience 4 times of tides a day along the

shoreline which the two are almost equal levels of high tides and another two are almost

same levels of low tides.

2.9.2 Spring Tide and Neap Tide

At most common cases, spring tide occur twice a month at the time of full moon

and new moon. The gravitational forces from the sun and moon combined together and

cause the tide to rise to higher and fall lower than the average tide (Fisheries and

Oceans Canada).

Same goes to neap tide, it also occurs twice a month. Neap tide is formed at the

time of first and quarter moon phase when the sun, earth and moon form a right angle.

The gravitational forces by moon and sun that exerted to the earth are destructing each

other causing the tide to reduce to lower level than the average (Fisheries and Oceans

Canada). The illustration of the combination of lunar and solar equilibrium tides to

produce spring tides at new and full moon and neap tides at first and last quarter of

moon phase was shown in Figure 2.7 and 2.8.

21

Figure 2.7: Combination of lunar and solar equilibrium tides to produce spring tides at

new and full moon and neap tides at first and last quarter of moon phase (Fisheries and

Oceans Canada).

Figure 2.8: Tide phases and moon phases (Lecture notes for Astronomy 100, 2011).

22

2.10 Currents

Ocean currents are very important in littoral transportation of sedimentary

particles along the shore line. Current can be divided into four types which are: 1 – Rip

currents; 2 – Density currents; 3 – Longshore currents and; 4 – Current of mass

transport. Rip and density currents move particle away from the beach while longshore

currents move particles parallel along the shore. Current of mass transport move

sediments on the shore with their strength (Macdonald E.H. 1973).

2.10.1 Rip Currents

According to National Oceanic and Atmospheric Administration, rip currents

are water currents that act perpendicular away from the water flow. Typically, rip

currents formed at low spots or breaks in sandbars and also near structures such as

jetties as shown in Figure 2.9. Rip currents can be very narrow to hundreds of meters.

The movement of current towards the sea varies. Sometimes it can end just after the line

of breaking waves or maybe can continue to push hundreds of meters offshore. This

type of currents carries materials away from the beach into deeper water.

Figure 2.9: Rip current formations at lowest point of an offshore bar.

23

2.10.2 Density Currents

Density currents are formed due to the difference in density of fluids. The

material will flow away from the shore since the fall of pressure is away from the shore.

This type of currents may help in erosion of one beach by transporting materials away

from the beach or contribute to the formation of another shore by supplying materials to

a new beach (Macdonald E.H. 1973).

2.10.3 Longshore Currents

Longshore currents is formed when waves strikes the beach at an angle. The

transportation of sedimentary particles along the continental shelf by this current can

create a zigzag pattern of particles movement along the shore. Longshore current is

shown in Figure 2.3 (Woods Hole Group, 2011)

2.10.4 Currents of Mass Transport

When waves moves to shallower part of the beach, the wave orbits formed

below the wave are flattened causing expansion of their energy which can contribute to

the movement of sediments towards and away from the shore. Since it is very slight,

but, it also assists the movement of particles towards the shore (Macdonald E.H. 1973).

24

2.11 Wind

Wind also plays an important role in transporting material from frontal dunes to

higher level without helping of wave from the sea. Some of the steady build-up along

the coastline is the only part of general migration of sand away from the beach.

Heavy mineral are redistributed by the wind action after being distribute by the

wave action. Onshore wind causes waves to steepen and become destructive while

offshore winds flatten seas and lead to build up. Both onshore and offshore wind may

erode the beaches by the removal of sands in the direction of winds (Macdonald E.H.

1973).

25

CHAPTER 3

RESEARCH METHODOLOGY

3.1 Introduction

In this study, 5m width and 8m long of black sands deposit area along the shore

was stripped to 1 inch depth to know the rate of new black sands deposit to recover back

the excavated black sands deposit to the original beach level and to determine the new

beach level on the excavated black sands deposit area after the high tide effect. Samples

of black sands deposit were also taken at 7 marked points around the area of study twice

a day during low tide each day.

In this study, the black sands deposit samples were dried first before further

analyses were carried out. Samples of black sands deposit undergo further physical

separation analysis to determine their heavy minerals concentration of the black sands

deposit. The analysis was done by using mozley table to know the percentage of heavy

minerals and the percentage of light minerals of the black sands deposit at every point

after the tides effect on a day before.

Mineralogical study of the sample is also done to determine the minerals present

in the black sands deposit. The mineralogical study is done by using optical microscopy

analysis and Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy

(SEM-EDX) analysis. Magnetic separator and high tension separator were used to

determine the minerals based on mineralogical behaviour of the present minerals before

microscopy study is done to identify the minerals present based on tis properties.

26

Finally, the data obtained from the site and lab were analysed and tabulated to

determine the level of the excavated black sands deposit after redistributed and to

determine the concentration of heavy mineral of the black sands deposit.

Based on the objective and the scope of research, an overall process flow-chart

of the study was proposed for designing and evaluating work to be done in this beach

mining research effectively. Some of the factors to study the beach mining method are

to designing the less environmental mining method at that area and to obtain a set of

data with are reproducible values within the required limits. It is simple, but yet

practical for the purpose of further studies. The overall process flow-chart are shown in

Figure 3.1.

27

SITE STUDY

LAB ANAYSIS

Evaluation and Design of Beach Mining in Pantai Pasir Hitam, Langkawi.

Literature study Geological research on formation of Langkawi

Island. Acquire permission from JMG for research study. Tide level analysis.

Determine the proposed area Block 5m width × 8m long of beach area towards

the sea. 7 Points of interest are marked with stakes.

Stripping Samples were taken at the 7 marked points before

stripping to evaluate the original heavy mineral concentration.

Strip the beach placer within 1 inch of depth to represent strip mining in small scale.

Redistribution of beach placer deposit New levels of the refilled beach placer are recorded

2 times a day after high tide at all marked points. Samples are taken after each high tide for heavy

mineral evaluation.

28

EXPERIMENTAL ANALYSIS

Figure 3.1: The flowchart of research work

Evaluation of heavy minerals Dry all samples Sampling process using Jones Riffles sampler. Gravity separation using Mozley table

Minerals Identification Determination of minerals according to their

physical properties using magnetic separator and high tension separator.

The separated samples were studied under Optical Microscope.

Raw sample of black sand deposit is analysed using SEM-EDX Spectroscopy and X-Ray Fluorescence (XRF) analysis.

Data analysis

Conclusion and recommendation

29

3.2 Literature Investigation

3.2.1 Geological Study

One of the first considerations before conducting the evaluation of black sands

deposit by the stripping mining method is to determine the source of valuable mineral

geologically. Reference of formation of Langkawi Island is made by relevant sources

such as Geological Survey of Malaysia conducted by National Mapping Malaysia.

Figure 3.2: General geologic maps of Langkawi Island (Geological Survey of

Malaysia, 2013)

30

The source of heavy mineral in the beach placer should be determined at the

early stage of exploration to study the formation of valuable heavy mineral whether it

comes from igneous rock of Triassic age or sedimentary rock of late Devonian or

Carboniferous age. Topographical features around Pantai Pasir Hitam area also

investigated to understand the condition of site, the surrounding geology, and the shape

of beach area.

3.2.2 Tide Analysis

During desk study, tide forecast from Malaysian Meteorological Department

(JMM) was studied to determine the time range for high tide to occur. Spring tide or

high tide was chosen because the strength of wave during this time is stronger and the

sea level is also higher compared to the average sea level. These factors contribute to

higher tendency for transporting the beach placer towards the shore which is very

preferable in this study. Figure 3.3 to 3.6 shows the data taken by Sea Level Station

Monitoring Facility at Langkawi Station on 8th January to 5th February 2013 (Sea level

station monitoring facility, 2013). From that study, the date of 24th to 28th January 2013

was chosen for site studies.

Figure 3.3: Sea level at Langkawi station on 8th to 15th January 2013.

31



Figure 3.6: Sea level at Langkawi station on 29th January to 5th February 2013.

32

3.3 Site Study

Site studies are done to meet the main objective of this project and the research

scope. Primary exploration is to establish an estimation of ore reserves, their volume

and grade, calculate the mine life of mining operation and potential profit (Hartman

H.L. et al., 2002). But, due to time restriction, equipment technologies, objective and

scope of project, the primary exploration of this project is only done to investigate the

origin of black sands deposit, rate of black sands deposit to recover back the excavated

black sands deposit to original level and also the concentration of heavy minerals in


3.3.1 Area Determination

After literature and geological study has been done, the site area has been

purposed for further investigation. Pantai Pasir Hitam is one of the main attraction

location for tourists because of the uniqueness of the black sand and the only location in

Malaysia that has black sand. Since, it is the main attraction area, the area for study

should be less of distraction to avoid error in obtaining the result of this study. The

proposed area is shown in Plate 3.1.

33

Plate 3.1: Study area (Red Box) at Pantai Pasir Hitam, Langkawi.

3.3.2 Marking Out

In marking out grids for beach mining evaluation, the traces of light sand and

shells that transported by the effect of wave from previous day act as an indicator to the

level of the high tide on previous night. From that estimation, a grid lines are

established along the indicator level. Having established the grid lines, a series of stakes

are fit inside the beach deposit is marked out for further investigation. The illustration of

the study area is shown in Figure 3.7.

34

Figure 3.7: Illustration of sampling point at study area.

Plate 3.2: Sampling point at study area and the marks on each stakes as indicator to

determine the level of black sands deposit.

E1 A1 B2

B2

B4

B6 D6

D4

C3

D2

D1

E5 A5

Traces of shells

Sea

Stripping area

35

Each of the stakes is marked with permanent marker pen for estimation of the

new level of black sands deposit after redistributed after high tide. 5 marks with interval

of 1 inch is marked on the stakes to indicate the beach level before and after

redistributed. The stakes are buried inside the black sands deposit until it reaches the

middle indicator to indicate the original level of black sands deposit. Plate 3.2 shows the

actual sampling point and the stakes indicator used in this investigation.

Yellow dotted line in Figure 3.7 represents the area of small scale stripping

mining need to be done for this study. The stripping area is 5m width × 8m long

towards the beach. In both pictures above, red and green dots represent the interested

area of study and analysis that need to be done. Red dots represent the points where

heavy mineral evaluation and determination of black sands deposit level after

redistributed by wave effect need to be done. Green dots represent points where it only

interested in the determination of black sands deposit level after being redistributed.

3.3.3 Striping

Strip mining is selected instead of other mining method in this research study

because of the adverse impact of beach mining activities. Despite of using this method,

this study is done to provide a good mining practise with a suitable planning schedule of

excavation to reduce the impact to the environment and also to the beach itself. In this

study, stripping is done once a day on the early morning.

Strip mining is done in small scale to determine the new level of black sands

deposit after being distributed by the high tide and also the concentration of heavy

mineral that being replaced with the excavated deposit. Stripping is done by using soil

shovel to excavate the black sands deposit within a depth of 1 inch. Plate 3.3 and 3.4

shows how the stripping of black sands deposit is done.

36

Plate 3.3: Method of strip mining for evaluation of black sands deposit.

Plate 3.4: Method of strip mining for evaluation of black sands deposit.

37

3.3.4 Sampling Activities

Sample collection is being done in two times a day after the occurrence of the

two high tides. There are 7 samples that collected in each series of sampling activities.

The samples are collected on the red dots points shown in Figure 3.7. First series of

sampling activity are taken before the stripping mining is done. This is done to estimate

the original concentration of heavy minerals in the black sands deposit before being

disturbed. Next samples were collected in the early morning and late afternoon during

the low tides on each day to determine the concentration of heavy minerals after

redistributed during high tide. The samples are collected by using grab sampling or

surface sampling by using soil shovel.

Plate 3.5: Soil shovel used for stripping and sampling of black sands deposit.

38

3.3.5 Rate of Redistribution Analysis

Rate of redistribution analysis is done to determine the new levels of the refilled

black sands deposit after redistributed during high tide on each day. The new levels are

recorded 2 times a day after high tides at all 13 marked points. The data are taken on all

red and green dots points shown in Figure 3.7.

Before stripping is done, all the stakes are marked with permanent marker pen to

act as a ruler for determining the level of black sands deposit. The stakes is marked with

5 marks with interval of 1 inch along the stakes. Firstly, the stakes are embedded into

the ground until it reaches the middle of the marks. This mark indicates the original

level of black sands deposit. Plate 3.2 shows the actual sampling point and the stakes

indicator used in this study.

After stripping is done, the level of black sands deposit reduces to about 1 inch.

The stripping area is left for half day for high tide to take effect. . The new level data

were collected in the early morning and late afternoon like sampling activities during

the low tides 2 times a day. The data were used for redistribution analysis in

determining rate of new black sands deposit to recover back the excavated black sands

deposit to the original beach level.

39

3.4 Experimental Analysis

The overall process flowchart of this research was shown in Figure 3.1. The

objective of this analysis is to calculate the concentration of heavy mineral present in

the black sands deposit and also identify the mineral present in the black sands deposit.

Determination of heavy mineral concentration in black sands deposit was done by using

gravitational separation method to separate the light and heavy minerals accordingly.

Mineral present in black sands deposit are being identified according to their physical

properties. Magnetic and high tension separator was used to separate this sample before

evaluated using Transmitted Polarizing Microscope.

3.4.1 Evaluation of Heavy Minerals

Sampling preparation was carried out on the sample before any experimental

process can proceed. Sampling plays a very important role in experimental analysis.

Any improper sampling will result in experimental error and the data expected may not

achieve. Therefore, sampling is done properly to ensure the samples are homogenous as

well as labelling.

40

Figure 3.8: Detail flowchart for heavy minerals evaluation.

Sample collected from Pantai Pasir Hitam was dried first in an oven for one day

at 100oC to ensure the sampling is done perfectly. The dried samples were then

undergoes sampling process by using Jones Riffles sampler until weight of 70g to 120g

are achieved. The remaining samples were kept for future reference and research.

Evaluation of Heavy Minerals

Dried in oven for 1 day at 103 oC

Jones Riffles sampling - Separate until 70 to 120g is achieved.

Sieve (1.4mm)

Particles (>1.4mm) Particles (<1.4mm)

Mozley Table

Light minerals

Heavy Minerals

Weight the sample

Weight the dried sample

Weight the dried sample

Light minerals

Mozley Table

41

The separated samples were further separated by using 1.4 mm sieve. This is

done to increase the efficiency of Mozley table for further gravity separation. Moreover,

the heavy minerals were found only in fine size (less than 1 mm). Fine samples were

then separated by using Mozley table. The separation is done for two times for each

sample to increase the heavy mineral recovery and reduce the amount of light mineral in

concentrate. Calculation is done to determine the percentage of heavy mineral in all

samples. Detail flowchart for heavy mineral evaluation is shown in Figure 3.8.

3.4.1.1 Mozley Table

The Mozley table is mainly used in mineral processing laboratories and not

suitable to be used in large scale industries as the operation can be done in a small scale.

Mozley table was designed to treat a small scale sample around 100 g. The shaking

process produce orbital shear on the sample allowing the heavy particles in the flowing

film to settle while the suspended light particles pass to the tailings.

Mozley table was used in this research to determine the concentration of heavy

mineral in black sands deposit. Through this gravity concentration separation, the black

sands deposit are separated according to their specific gravity. Heavy mineral will stay

in the tray while light minerals are discharged with the water flow. In this analysis, 70

to 120 g of black sands deposit is separated by using mozley table. The product of

heavy minerals is collected in a beaker while the light particle from the tailing was

repeated for second time to increase the recovery of heavy minerals.

42

3.4.2 Mineral Identification

The valuable minerals found in black sands deposit have specific gravity which range

from 3.7 to 7.1. These minerals are resistance to weathering and physical abrasion and

usually found as granular materials with particle size distribution between 1.4 mm to

0.074 mm (Macdonald E.H. 1973). This minerals need to be analysed to identify the

minerals present in the black sands deposit. Two methods are done for identification of

black sands mineral. The methods are done by using optical microscope for physical

analysis and Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy

(SEM-EDX) analysis.

Remaining samples from the previous experiment is further split into two. First

samples are divided for SEM-EDX analysis. The other part was used for physical

analysis. In physical analysis, the samples are separated using magnetic separator to

separate the magnetic minerals. Then, both of the separated samples are run through

high tension separator to determine the minerals which conductor or not. All the

separated samples are then analysed under Optical Microscope Microscope. Detail

flowchart shown in Figure 3.9.

43

Figure 3.9: Detail flowchart for mineral identifications.

Minerals Identification

SEM-EDX analysis & XRF analysis

Physical analysis

Magnetic Separator

Non-Magnetic Minerals

Weight the sample

Jones Riffles sampling

Magnetic Minerals

High-tension Separator

Non-Conductor Minerals Non-

Conductor Minerals

High-tension Separator

Non-Conductor Minerals

Conductor Minerals

Optical Microscope

44

3.4.2.1 Magnetic Separator

Magnetic separators are used for separating heavy mineral concentrates into

magnetic and non-magnetic fractions. Magnetic separators can be used to separate

different types of magnetic particles depending on the type of the separator used. They

can separate either diamagnetic, paramagnetic or ferromagnetic particles by using high

intensity magnetic separator usually known by ‘HIMS’ or low intensity magnetic

separator which are known by ‘LIMS’. The operation of these separators can be

performed in wet or dry condition depending on the process (Wills B.A. et al., 2006).

In this research, dry magnetic separation method was performed to separate

magnetic minerals in black sands deposit such as ilmenite and any magnetic minerals

from the sample. Rare earth magnetic roll separator was used to separate sample black

sands deposit to for mineral identification.

Sample was run 3 times with appropriate feeder speed and roller speed to

achieve a good separation. The magnetic separator was run at feeder speed of 5 rpm and

roller speed of 12 mpm (meters per minute). Both of magnetic and non-magnetic

samples were observes under optical microscope for mineral identification.

3.4.2.2 Electrostatic (High-Tension) Separator

Electrostatic separators are used for separating heavy mineral concentrates into

conductor and non-conductor fractions. There are two forces that working together in

separating a material in those fractions. The forces are gravitational forces and

electrostatic attraction. Particles are charged by a corona discharged while flowing on a

drum. Conductor materials will lose their charged and repelled to one fraction and non-

conductor materials will stay on the drum until swiped out to the other fraction (Wills

B.A. et al., 2006).

45

In this study, non-conductor sample was run three times to achieve a good

separation. After being separated, the fractions were run under optical microscope for

mineral identification.

3.4.2.3 Optical Microscope

In this study, optical microscope is be used in identifying mineral based on the

physical characteristic of minerals. Experience observers may differentiate between the

numbers of minerals present using hand lens only. However, for detail mineralogical

identification, chemical and physical examination need to be conducted.

A microscopic study of the sample is important in identifying the minerals

present in the black sands deposit. Understanding mineral constituent in the samples

provide useful information especially in estimation of ore reserved, mineral economics,

mineral processing methods required, etc. For this research, 4 separated samples from

high-tension separators were observed under microscope to determine the minerals

present in the black sands deposit sample.

46

3.4.2.4 Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy

(SEM-EDX)

The scanning electron microscopy is versatile non-destructive equipment used to

characterize solid sample. SEM used a focused beam high-energy electrons to generate

a variety of signals at the surface of solid specimens. The sample scanned must be

electrically conductive, at least at the surface, and electrically grounded to prevent the

accumulation of electrostatic charge at the surface. If the sample is conductive, coating

is needed (Surface Science Western). In this research, sample of black sand is coated

with gold first because there are some minerals that are non-conductive present in the

sample.

EDX is an analytical technique used for elemental analysis or chemical

characterization. In this experiment, FESEM Machine SUPRA 35VP ZEISS equipped

with EDX is used to analyse the raw sample to determine the minerals present in the


3.4.2.5 X-ray Fluorescence (XRF) Analysis

X-ray Fluorescence (XRF) test is being doing to know the chemical composition of

the beach placer sample. The preparations of doing XRF test are being doing properly to

avoid the contamination of the sample with the other material. For this test, 25 grams of

grinding samples which are below 75μm are needed.

XRF test is the most efficient technique to know the definite chemical composition

of the material especially beach placer samples without destroyed the samples.

Radioactive waves that call X-Ray are being using to test the specimen. This specimen

will be reacted or activated and become excited and will produce that ray. The X-ray

will hit the electron in the atom of the sample and cause the one empty electron in thee

47

orbit. Electron from the outer orbit will move into inner orbit in the atom. The X-ray

will be emitted from these this moving. A detector machine are been using to measure

the strength and position of the ray that has been emitted. The position of the ray will be

detected to know the types of the elements and the strength of the ray is for the intensity

of these elements. All the elements can be analysed by XRF test except hydrogen,

helium, and lithium elements. The XRF machine is consist three main parts that are

source of the ray, crystal spectrometer and the detector. (Oxford-XRF, 2012)

48

CHAPTER 4

RESULT AND DISCUSSION

4.1 1ntroduction

This chapter will present the data and results obtained from the research and

experiments conducted in this project. The data and results that have been recorded will

be discussed in detail in this chapter.

4.2 Site Study

The project site is Pantai Pasir Hitam that located in Langkawi Island in Kedah

state. Referring to geological map of Langkawi Island, Pantai Pasir Hitam area is

surrounded by 2 types of rock which are 1- granite rock from Triassic age and 2 –

Mudstone, siltstone and shale from late Devonian or Carboniferous age.

From physical observation on topographical features around the site area, the

heavy mineral can be seen clearly to be distributed due to the wave action. Based on

Plate 4.1, there are no traces of heavy minerals from the banks near the beach area. The

heavy minerals are found only in the foothills along the beach until several meters under

the sea as shown in Plate 4.2. These minerals are being transported from the sea to the

shore by the wave action.

Plate 4.3 shows granitic rocks that contain black minerals which are likely to be

one of the parent rocks of these minerals. These minerals are then liberated by

weathering process when the materials are in contact with water and other rocks. Plate

4.4 shows holes and soils that had been dig by crabs called burrows. A layer of lighter

sand on top of black sand can be seen clearly indicate the present of black sand down

under the surface. Based on theory, crabs will make its burrow for several inches and

49

arrange them orderly on the surface. From that theory, it can be said that, the heavy

minerals can also be found inside the beach placer until several inches until the end of

the holes and maybe deeper.

Plate 4.1: Heavy mineral deposit present only on foothills along the banks at beach area.

50

Plate 4.2: Distribution of heavy minerals along the shoreline and under the sea.

Plate 4.3: Source of the heavy mineral deposit.

51

Plate 4.4: Burrows made by crabs.

Based on the physical observation along the shore line of Pantai Pasir Hitam, it

can be conclude that the beach placer deposits are transported by the wave action from

the sea towards the shore. One of the sources of heavy minerals that form the black sand

at that area is from the weathering process of granitic rock under the sea. The beach

placer can be found from several inches to several meters under the beach.

4.3 Rate of Redistribution Analysis

Heights of beach placer deposit are observed in this analysis to determine the

new levels of the refilled beach placer after redistribution by wave action. The data are

recorded from 13 marked point shown in Figure 3.7. The data were taken 2 times a day

after high tide to determine the increments of the beach placer levels after redistributed

by the wave action.

52

4.3.1 Day First (24.01.13)

On the first day, the stripping area was stripped about 1.5 to 2.0 inches deep

from the original surface level. But, not all marked points could be stripped on this day

because the level of water had been rise into the proposed study area while stripping

being done. On this day, sea level is ±2 m from the mean sea level as shown in Figure

3.5. Data of the first stripped levels are shown in Figure 4.1.

Figure 4.1: New beach placer level on 24.01.13 after first stripping.

After completed stripping the upper surface, the sea level keep on increasing until it

reach the middle part of the stripped surface. The high tide on this morning cannot

cover the upper part of the proposed area which causes no change in the beach level on

the top of stripped area. After 11.30 am, the sea level decreases until all the proposed

points are exposed. Data after day tide on this day is shown in Figure 4.2. After the data

has taken, the whole area was stripped about 2.0 inches deep from the original surface.

A1 B1

B2

B6 = -2.0”

D2

D1

Sea

Stripping area

E1

9.00 am – Rising

D6 = -2.0”

A5 = -2.0” E5 = -2.0”

D4 = -1.5” B4 = -1.5”

C3 = -1.5”

53

Figure 4.2: Data of beach placer level on 24.01.13 at evening.

Plate 4.5: Sea level was raising during stripping is done.

A1 B1

B2

B6 = -2.0”

D2

D1

Sea

Stripping area

E1

11.30 am - Max

D6 = -2.0”

A5 = -2.0” E5 = -2.0”

D4 = -0.6” B4 = -0.5”

C3 = -0.5”

54

4.3.2 Day Second (25.01.13)

On the second day, levels of beach placer deposit were recorded before stripping

was done. But, some of the sampling points data cannot be recorded because the stakes

was submerged in the sea. Water ripples, refraction and clarity of water prevent the data

to be taken accurately. Sea level on 25th January was ±2.2 m from the mean sea level as

shown in Figure 3.5. Data of the sea levels after high tide are shown in Figure 4.3.

Figure 4.3: Data of beach placer level on 25.01.13 at morning.

Stripping was not done on this day to allow the wave action to further transport

the beach placer to the shore. During low tide at evening, levels of beach placer were

taken again to estimate the rate of distribution of beach placer along the shoreline. Data

recorded at the evening is shown in Figure 4.4.

A1 B1

B2

B6 = -1.5”

D2

D1

Sea

Stripping area

E1

10.40 am – Sea level (rising)

D6 = -1.5”

A5 = -1.6” E5 = -1.2”

D4 = -1.6” B4 = -1.6”

C3 = -1.0”

55


Plate 4.6: Site area on 25.01.13 at evening.

B6 = -1.0”

Sea

Stripping area

D6 = -0.5”

A5 = -1.0” E5 = -0.4”

D4 = -1.0” B4 = -1.1”

C3 = -0.5”

B2 = -0.4” D2 = -0.6”

A1 = -0.8” B1 = -0.5” D1 = -0.4” E1 = -0.4”

6.00 pm – Sea level (rising)

56

4.3.3 Day Third (26.01.13)

On third day, levels of beach placer deposit were recorded before stripping and

done like previous day. Data of the sea levels recorded are shown in Figure 4.5. The

proposed area was stripped on this day until depth 2.0 inch deep from the original

surface. Work need to be done fast on this day because sea level increasing rapidly as

spring tide is becoming higher on this and the next day. From the tide analysis, high tide

would be ±2.5 m from the mean sea level as shown in Figure 3.5.


After stripping is completed, the sea levels keep on increasing until it covers up

all the stripped area as soon as 11.00 am. On this day, the beach placers can be

distributed earlier than the previous day because high tide is becoming higher. At

evening, after the sea level was dropping, data of sea levels were recorded and is shown

in Figure 4.6.

B6 = -0.8”

Sea

Stripping area

D6 = -0.9”

A5 = -0.5” E5 = -1.0”

D4 = -1.2” B4 = -1.3”

C3 = -1.0”

B2 = -0.3” D2 = -0.5”

A1 = -0.2” B1 = -1.1” D1 = -0.4” E1 = -0.2”

11.00 am – Sea level (rising)

57


Plate 4.6: Site area on 26.01.13 at morning.

B6 = -1.4”

Sea

Stripping area

D6 = -2.1”

A5 = -1.0” E5 = -1.2”

D4 = -1.5” B4 = -2.0”

C3 = -1.3”

B2 = -1.1” D2 = -1.2”

A1 = -1.0” B1 = -1.1” D1 = -0.8” E1 = -1.0”


58

4.3.4 Day Fourth (27.01.2013)

As usual, levels of beach placer deposit were recorded before stripping was

done. The area was stripped to depth 2.0 inches as usual. From the tide analysis, high

tide would be ±2.6 m from the mean sea level as shown in Figure 3.5. Sea level was

increasing ±0.1 m from the previous day. But at site, the maximum level of sea water at

morning was at the highest point of the striping area which is lower than previous day.

Data of beach placer levels recorded at the morning is shown in Figure 4.7.


After stripping is completed, the sea levels keep on increasing until it covers up

all the stripped area at 11.30 am. On this day, the sea level is not increasing as expected,

the maximum height of sea level is lower than previous day, but it still cover up all the

stripping area. At evening, after the sea level was drop, data of sea levels were recorded

and is shown in Figure 4.8.

B6 = -0.8”

Sea

Stripping area

D6 = -0.9”

A5 = -0.5” E5 = -1.0”

D4 = -1.2” B4 = -1.3”

C3 = -1.0”

B2 = -0.3” D2 = -0.5”

A1 = -0.2” B1 = -1.1” D1 = -0.4” E1 = -0.2”

11.30 am – Sea level (max)

59


B6 = -1.2”

Sea

Stripping area

D6 = -1.4”

A5 = -1.3” E5 = -1.2”

D4 = -2.0” B4 = -2.4”

C3 = -1.5”

B2 = -1.0” D2 = -1.3”

A1 = -0.5” B1 = -1.1” D1 = -0.6” E1 = -0.5”


60

4.3.5 Day Fifth (28.01.2013) – Last Day

At this morning, no stripping was done. Only data of the beach placer levels

were collected in this day to obtain the data of the effect of high tide at night day before.

According to tide analysis data, high tide on this day would be ±2.8 m from the mean

sea level as shown in Figure 3.5. Data of the beach levels are shown in Figure 4.9.


After the data from each day have been recorded, the data were combined in

Table 4.1 to make the comparison of the data obtained on each day is easier. Table 4.2

shows the increments of beach placer levels at each sampling points after calculations is

done.

B6 = -1.3”

Sea

Stripping area

D6 = -1.5”

A5 = -1.2” E5 = -1.2”

D4 = -1.5” B4 = -2.5”

C3 = -1.2”

B2 = -0.8” D2 = -1.0”

A1 = -0.4” B1 = -1.0” D1 = -0.5” E1 = -0.5”

61

Table 4.1: Simplified data of beach placer deposits levels.

Date

Points

Levels of Beach Placer Deposits (inch)

24.1.13 25.1.13 26.1.13 27.1.13 28.1.13 First

Stripping Day tide Night tide Day tide Night tide Day tide Night tide Day tide Night tide

A1 - - -1.4 -0.8 -0.2 -1.0 -0.4 -0.5 -0.4

B1 - - -1.4 -0.5 -1.1 -1.1 -0.6 -1.1 -1.0

D1 - - -1.4 -0.4 -0.4 -0.8 -0.7 -0.6 -0.5

E1 - - -1.4 -0.4 -0.2 -1.0 -0.5 -0.5 -0.5

B2 - - -1.4 -0.4 -0.3 -1.1 -0.5 -1.0 -0.8

D2 - - -1.4 -0.6 -0.5 -1.2 -0.8 -1.3 -1.0

C3 -1.5 -0.5 -1.0 -0.5 -1.0 -1.3 -1.4 -1.5 -1.2

B4 -1.5 -0.5 -1.6 -1.1 -1.3 -2.0 -2.0 -2.1 -2.2

D4 -1.5 -0.6 -1.6 -1.0 -1.2 -1.5 -1.0 -2.0 -1.5

A5 -2.0 -2.0 -1.6 -1.0 -0.5 -1.0 -1.1 -1.3 -1.2

E5 -2.0 -2.0 -1.2 -0.4 -1.0 -1.2 -0.7 -1.2 -1.2

B6 -2.0 -2.0 -1.5 -1.0 -0.8 -1.4 -1.2 -1.2 -1.3

D6 -2.0 -2.0 -1.5 -0.5 -0.9 -1.1 -1.3 -1.4 -1.5

Remarks First Stripping

Level after first

stripping

Level after stripped to -2.0

Level after

stripped to -2.0

Level after

stripped to -2.0

62

Table 4.2: Overall increments of beach placer deposits.

Date

Points

Increments of Beach Placer Deposits (inch) 24.1.13 25.1.13 26.1.13 27.1.13 28.1.13

First Stripping Day tide Night tide Day tide Night tide Day tide Night tide Day tide Night tide

A1 - - - 0.6 0.6 1.0 0.6 1.5 0.1

B1 - - - 0.9 -0.6 0.9 0.5 0.9 0.1

D1 - - - 1.0 0 1.2 0.1 1.4 0.1

E1 - - - 1.0 0.2 1.0 0.5 1.5 0

B2 - - - 1.0 0.1 0.9 0.4 1.0 0.2

D2 - - - 0.8 0.1 0.8 0.4 0.7 0.3

C3 - 1.0 1.0 0.5 -0.5 0.7 -0.1 0.5 0.3

B4 - 1.0 0.4 0.5 -0.2 0 0 -0.1 -0.1

D4 - 0.9 0.4 0.6 -0.2 0.5 0.5 0 0.5

A5 - 0 0.4 0.6 0.5 1.0 -0.1 0.7 -0.1

E5 - 0 0.8 0.8 -0.6 0.8 0.5 0.8 0

B6 - 0 0.5 0.5 0.2 0.6 0.2 0.8 -0.1

D6 - 0 0.5 1.0 -0.4 0.9 -0.2 0.6 -0.1 Average

Increments - 0.9 0.6 0.7 -0.1 0.8 0.2 0.8 0.1


Level after first

stripping

Level after stripped to -2.0

Level after

stripped to -2.0

Level after

stripped to -2.0

63

There are two cases in calculating the increments of beach levels. The first case is

calculation when stripping is done and second case is calculation when stripping is not

done.

i. For the first case, the formula to calculate the increments of beach levels is:

Increments = Beach level after stripping – New levels after tides

ii. For the second case, the formula is:

Increments = Beach level of the previous tides – New levels after tides

Based on the result in Table 4.2, it can be say that the increments of beach placer

are higher when stripping is done compared to the increments when stripping is not

done. The increments is higher because when the beach level is skimmed and become

lower, sea water can transport higher amount of beach placer more easily to the beach.

Tide forecast shown in Figure 3.5 shows the tide level on 24th to 28th January are

increasing from 1.5 m to 2.5 m from mean sea level and shows the high tide on night is

higher than morning. But from the research conducted, the average increments of beach

placers are around 0.8 inches if the beach placers are stripped before tide on morning

(day tide). While, the increments of beach placer when stripping is not done is only 0.1

inches (night tide). The overall average increments calculation is shown in Appendix C.

Even the night tide is stronger than the day tide, the increment of night tide are always

lower than the increment after the day tide. This may be due to the presence of barrier

or sea walls in front of the beach that may reduce the strength of the wave as shown in

Plat 4.7. This shows that even the night tide is higher than morning, the wave still

cannot increase the beach level because transportation of beach placers are depend on

the strength of the waves and the level of the beach.

64

Plate 4.7: Presence of barrier or sea walls at the sea area.

On 26.01.13 after night tides, the result shows the beach levels reduce to 0.1

inches compared to the previous levels. From the details of the experiment on that

particular date, it shows that beach level at most of the sampling points at the upper part

of sampling area are decreased compared to the beach level form the previous tides.

Only the lower part of the sampling points shows increments compared to the previous

tides. From this observation, it can be said that the beach placer on the upper part are

transported to the lower part of the sampling area on this day.

65

4.4 Evaluation of Heavy Minerals

In this analysis, separation is done to determine the percentage of heavy

minerals and light minerals. Mozley table is used in this analysis to separate the heavy

and light minerals. Evaluations of heavy minerals were done only at 7 points which are

marked red as shown in Figure 4.10.

Figure 4.10: Illustration of sampling point at study area.

Evaluations cannot be done at the green marked points to avoid the sample from

contaminated with the beach placer at the surrounding of the stripping area. Therefore,

only samples at red points are being evaluated to determine the concentration of heavy

minerals after redistributed by the wave actions. Detail data of the heavy mineral

evaluation are shown in Appendix B.

E1 A1 B2

B2

B4

B6 D6

D4

C3

D2

D1

E5 A5

Sea

Stripping area

66

Data from the Appendix B are calculated to get the percentage of heavy mineral

that being redistributed by the wave action during high tides on each day. The

percentage of heavy mineral was calculated by using formula:

Percentage Concentrate (%) = Mass of Concentrate (g)

Mass of Concentrate (g) + Mass of Tailing (g)

The results obtained from Appendix B are summarized in Table 4.3.

67

Table 4.3: Summarized data of heavy mineral concentration in beach placer deposits.

Date

Points

Concentration of Heavy Mineral in Beach Placer Deposit (%) Average Concentration

(At Each Sampling

Points)

24.1.13 25.1.13 26.1.13 27.1.13

Initial Sample Day Tide Night + Day Tide Night Tide Day Tide Night Tide Day Tide

B1 - - 61.62 48.12 32.65 41.56 44.56 45.70

D1 - - 73.03 46.07 25.45 37.98 49.57 46.42

B2 41.11 - 46.60 25.34 22.31 36.70 28.00 33.34

D2 54.01 - 47.47 44.16 29.36 41.54 29.25 40.97

C3 33.66 - 41.76 56.32 60.39 67.00 20.46 46.60

B4 22.01 48.83 40.21 72.93 63.34 63.72 24.20 47.89

D4 28.66 24.34 37.27 25.40 34.91 33.63 48.12 33.19 Average

Concentration (At Particular

Tide) 35.89 36.59 49.71 45.48 38.34 46.02 34.88

Average Increments - 0.9 0.6+0.7 -0.1 0.8 0.2 0.8


After First Striping

After Stripped to -2.0

After

Stripped to -2.0

After

Stripped to -2.0

68

Figure 4.11: Relation between beach increments and heavy minerals concentration in

black sand deposit.

From Figure 4.11, the concentration of heavy mineral in the beach placer was

not consistent at each point. But, the average percentage after each tide shows some

correlation with the increments of beach levels. The average heavy mineral

concentration of initial sample of black sand deposit is 36%. But after redistribution of

the black sand, average heavy minerals concentration is around 41% at particular tides

and around 42% at each particular sampling points depending on the variation of wave

coming from the sea. The percentage of heavy mineral may not be accurate because of

instrument efficiency especially when separation analysis by mozley table is done. The

overall average heavy mineral concentration on particular tides and sampling points is

shown in Appendix D.

Based on the result shown above, the average percentage of heavy mineral

shows an increasing pattern from 24th to 25th Jan 2013. On 24th Jan, the site was stripped

for -2.0 inches from the surface which affect the data after day tide. The result shows a

69

slightly increase of the percentage of heavy minerals compared to the initial

concentration of the heavy minerals.

On 25th Jan, the concentration of heavy mineral shows the highest which are

about 50%. This may be because of stripping is not done at the morning on this day

causing more heavy minerals to be transported by the wave action on the site area. The

increment of beach level which is higher than the other days shows more beach placer

deposit are transported to the stripped area in this day as no stripping is done.

On 26th Jan, the result of night tide shows some reduction in the percentage of

heavy minerals to 45%. The beach level also decreases to 0.1 inch on this morning. The

transportation of beach placer away from the sampling area may cause the beach level

and heavy mineral concentration decreases on this morning. After stripping is done, the

increments of beach level increase abruptly but the concentration of heavy mineral is

only 38% which are much lower than night tide at the next day.

On 27th Jan, the night tide continues increasing the concentration of heavy

minerals to 46% at the area. But the level only increase for 0.2 inch. This shows the

strength of night tide is stronger than the day tide. After stripping is done to 2.0 inch

below the original surface, the result shows increments of the beach levels at 0.8 inch

and 35% concentration of heavy minerals in the beach placer deposit. These results

produce a same pattern of average increments and also average concentration of heavy

minerals as the previous day.

70

4.5 Mineral Identification by Optical Microscope

Mineral identification is done by optical microscopy study. Sample was sieved

to below 0.7 mm before separated by using magnetic separator and high tension

separator (HTS) to classify the sample according to its physical properties effectively.

The sample was than analysed under optical microscope for better identification. From

this study, the most abundant minerals present in the samples can be determined and

this provides a useful data for the processing stage. Once the mineral have been

identified, the design of mineral processing can be develop at most efficient and

economical route to recover the valuable minerals. Figure in Table 4.4 and Table 4.5

shows microscopic images of the separated sample.

71

Table 4.4: Minerals form magnetic particles after separated using HTS.

Figure Images Observation

Figure 4.12:

Magnetic and

Conductor

1. Ilmenite (Most of the black particles).

2. Hematite

Figure 4.13:

Magnetic and

Non-Conductor

1. Pyrite 2. Monazite 3. Tourmaline

Table 4.4 shows images of magnetic mineral after separated by using rare earth

magnetic roll separator. The Figure 4.12 on Table 4.4 is an image of magnetic and

conductor minerals after further separated by using HTS. Two expected minerals which

exhibits magnetic properties together with conductive properties was identified. The

two minerals are ilmenite and hematite. Ilmenite is the major mineral found in Figure

4.12 which is black in colour while hematite is brownish in colour.

1

2

1

1

2

3

72

Figure 4.13 shows a picture of minerals that exhibits magnetic properties

without conductive properties. The image shows the presence of three minerals which

are monazite, tourmaline and pyrite. Pyrite was found in this figure even it is non-

magnetic particles. This is because pyrite is appearing to be interlocked with ilmenite.

All of the ilmenite is supposed to be in magnetic and conductor mineral, but ilmenite

also appears in magnetic and non-conductor mineral showing that the efficiency of HTS

separator for this separation is low.

Table 4.5: Minerals form non-magnetic particles after separated using HTS.

Figure Images Observation

Figure 4.14: Non-

Magnetic and

Conductor

1. Rutile

Figure 4.15: Non-

Magnetic and

Non- Conductor

1. Zircon 2. Quartz

(Colourless to brownish in colour)

1

1

1

1

1

1

2

73

Table 4.5 shows non-magnetic minerals that exhibits conductive and non-

conductive properties. In Figure 4.14, rutile was found which are black in colour. Figure

4.15 shows the presence of zircon together with quartz. In this samples, quartz present

in different colours from colourless to brownish in colour. Quartz that stained with iron

appears in brownish colour. Rutile is present in Figure 4.15 even it is conductor mineral

while quartz is present in Figure 4.14 even it has undergo HTS separation. This proved

that the HTS separator is not efficient for this separation.

4.6 Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy

(SEM-EDX) Analysis

Raw sample from black sands deposit was sent for SEM-EDX analysis to check

for the minerals presence in the sample. The sample sent for EDX analysis was sieved

to below than 1.4 mm without any other physical separation. Figure 4.16 and 4.17

shows the raw sample image of black sand deposit with SEM at 50 times magnification.

Figure 4.16: SEM images of raw black sand at 50 times magnification

Figure 4.17: SEM images of raw black sand at 50 times magnification

74

Figure 4.18 to Figure 4.20 shows the data obtained from EDX analysis. From

the analysis, some of minerals cannot be identified because this analysis only produces

elements present in a particular particle. Figure 4.18 shows the presence of hematite,

zircon and quartz. Figure 4.22 shows ilmenite which appear to be interlocked with

quartz while Figure 4.25 shows image of interlocked hematite with quartz. Figure 4.28

shows the presence of tourmaline minerals in the raw sample of black sand.

Figure 4.18: SEM photomicrograph of raw black sand deposit sample.

Figure 4.18 shows the presence of three minerals in the raw sample which are

hematite, zircon and quartz based on the element presence by EDX analysis and the

shape of the particles. Zircon (ZrSiO4) was identified because its shape and the presence

of Zr element by EDX analysis. Hematite (Fe2O3) was also identified because the

presence of elements Fe, O and small amount of Si and Al element in the particle.

Quartz in this image is present with small amount of magnesium.

Zircon

Quartz Hematite

75

Figure 4.19: EDX diffractogram showing the presence of hematite in Figure 4.18.

Figure 4.20: EDX diffractogram showing the presence of zircon in Figure 4.18.

Element Wt% At% O 19.11 42.77 Al 03.62 04.81 Si 04.54 05.79 Fe 72.73 46.63

Element Wt% At% O 27.29 57.52 Si 18.77 22.54 Zr 53.94 19.94

76

Figure 4.21: EDX diffractogram showing the presence of quartz in Figure 4.18.

Figure 4.22: SEM photomicrograph of raw black sand deposit sample (different location).

Figure 4.22 shows ilmenite particle appears to be interlocking with quartz. EDX

analysis shows the presence of element Fe, Ti and O which can produce FeTiO3 and

indicate the presence of ilmenite on the light spot in the raw samples. The dark spot

shows the presence of ilmenite and silica based on the element present in EDX analysis.

Element Wt% At% O 45.32 58.52 Mg 05.17 04.39 Al 22.41 17.16 Si 27.10 19.93

Ilmenite

Quartz

77

Figure 4.23: EDX diffractogram showing the presence of ilmenite (light structure) in Figure 4.22.

Figure 4.24: EDX diffractogram showing the presence of quartz (dark spot) in Figure 4.22.

Element Wt% At% O 29.60 57.63 Ti 33.51 21.79 Fe 36.89 20.58

Element Wt% At% O 36.06 54.78 Al 16.75 15.09 Si 19.80 17.14 Ti 14.80 07.51 Fe 12.60 05.48

78


Figure 4.25 shows the images of hematite which appear to be interlocked with

quartz. In EDX analysis, hematite was identified based on the composition of Fe and O

in the sample. Although Al and Si are present, it is in small amount compared to Fe and

O. The dark spot only shows Si and O element which is absolutely clean quartz.

Figure 4.26: EDX diffractogram showing the presence of hematite (light colour) in Figure 4.25.

Element Wt% At% O 32.58 58.39 Al 04.03 04.28 Si 09.44 09.64 Fe 53.94 27.69

Hematite

Quartz

79

Figure 4.27: EDX diffractogram showing the presence of quartz (grey colour) in Figure 4.25.


Element Wt% At% O 42.66 56.63 Si 57.34 43.37

Tourmaline

80

Figure 4.28 shows the presence of tourmaline mineral in the raw samples.

Tourmaline was identified based on the presence of elements aluminium, iron,

magnesium, and potassium. The elements are same as biotite, but tourmaline is

expected based on the physical observation of the raw sample under microscope and

when doing the physical separation of light and heavy minerals. From the observation,

tourmaline was found to be present in the raw sample based on the dark black colour

and the specific gravity of the tourmaline.

Figure 4.29: EDX diffractogram showing the presence of tourmaline in Figure 4.28.

4.7 X-Ray Fluorescence (XRF) Analysis

Raw sample of black sand deposit at site area were sent for XRF analysis to

determine the elemental composition of the major and traces elements present in the

samples. Table 4.6 shows the XRF result of the raw sample.

Element Wt% At% O 24.80 41.10 Mg 06.32 06.89 Al 11.94 11.73 Si 24.87 23.48 K 07.73 05.24 Fe 24.35 11.56

81

Table 4.6: X-Ray Fluorescence (XRF) analysis for raw sample of black sand.

From Table 4.6, the elements that show high concentration are SiO2 with 78.86

wt%, Al2O3 with 6.59 wt%, Fe2O3 with 4.16 wt% and TiO2 with 1.25 wt%. The result

shows raw sample of black sand deposit contains mostly of quartz based on the highest

percentage of SiO2 in the analysis. Al2O3 shows the second highest percentage in raw

sample indicates the presence of garnet and maybe some other impurities form clay

minerals. Ilmenite, rutile, hematite shares the elements of TiO2 and Fe2O3 which

appears to be about 5 wt% of the raw sample. Zircon and monazite may present in the

sample because of the analysis shows traces of ZrO2 and P2O5 elements.

.

Composition Result (wt%) Composition Result (wt%) SiO2 78.8563 SO3 0.0132

Al2O3 6.5880 Nb2O5 0.0114

Fe2O3 4.1566 Cl 0.0106

TiO2 1.2445 ZnO 0.0075

K2O 0.6785 Rb2O 0.0053

MgO 0.6490 NiO 0.0043

CaO 0.2544 PbO 0.0036

MnO 0.2704 Y2O3 0.0028

Na2O 0.2537 Ga2O3 0.0027

ZrO2 0.1483 SrO 0.0026

Cr2O3 0.0186 ThO2 0.0016

P2O5 0.0160

82

CHAPTER 5

CONCLUSION AND RECOMMENDATIONS

5.1 Conclusion

This evaluation and design of beach mining in Pantai Pasir Hitam, Langkawi is a

preliminary study to evaluate the black sand deposit. The evaluation is done to identify

minerals present and the data after redistribution of the black sands deposit after being

stripped to several depths which have never been documented before.

From the microscopic study, it was found that the major mineral present in the

black sand beach is ilmenite. The other mineral that found associated with ilmenite are

hematite, pyrite, rutile, zircon, tourmaline, monazite and quartz. The SEM and XRF

analysis prove of the presence of these minerals based on the element and structure of

the minerals.

From physical observation on topographical features around the site area, the

heavy mineral can be said to be distributed due to the wave action because there are no

traces of black sand minerals from the banks near the beach area. The heavy minerals

are found only in the foothills along the beach until several meters into the sea. Granitic

rocks that contain black minerals are likely to be the parent rocks of these minerals.

These minerals are then liberated by weathering process when the materials are in

contact with water and other rocks. These minerals are being transported from the sea to

the shore by the wave action.

From the research conducted, the average increments of beach are 0.8 inches

when the black sand deposit is stripped before high tide. While, the average increments

of black sand deposit when stripping is not done is only around 0.1 inches. It can be say

83

that the increments of beach level are much higher when stripping is done compared to

the increments when stripping is not done. The increments is higher because when the

beach level is skimmed and become lower, sea water can transport higher amount of

beach placer more easily to the beach. Therefore, in real mining situation, the

excavation or stripping should be done at least 1 times in 2 days to make sure all the

excavated sand deposit has return to a stable condition if the excavation is done for 2

inch depth.

The presence of sea walls or barrier in front of the beach may be the factors of

reduction of the strength of the wave. Even the night tide is higher than morning (based

on the forecast), the night tide still cannot increase the beach level higher than the

increment on the day tide. This is because transportation of beach placers are depends

on the strength of the waves and also the level of the beach.

The concentration of heavy mineral in the beach placer was not consistent at

each point. But, the average percentage after each tide shows some correlation with the

increments of beach levels. The higher the increments of beach level, the higher the

amount of heavy mineral concentration in the black sand deposit. The average heavy

mineral concentration of initial sample of black sand deposit is 36%. But after

redistribution of the black sand, average heavy minerals concentration is increase to

41% at particular tides and 42% at each sampling points. The value may increase or

decrease depending on the variation strength of currents, wind, tide and wave coming

from the sea.

84

5.2 Recommendations

Since this is the first study about evaluation and design of beach mining in

Malaysia, there is a lot of way need to be improved especially in conducting the site

study. Therefore, more researches should be done before the data could be applied in

order to get more data due to the restriction of time in doing this research. The

following are the recommendation that can be improved for this research;

i. Since the result is only based on five days of studies, more time is need to

achieve better result to evaluate redistribution of the black sand because tide

is different for every days and repeated each month depending on the moon

phase.

ii. Type and direction of currents and wind also need to be noted when doing the

research to identify the direction of movement of the black sand deposit.

iii. Determine the best and suitable method to avoid the mixing of redistributed

black sand with the stripped and the surrounding black sand. It is

recommended to use pieces of woods on both sides of site area as a partition

to avoid mixing with the surrounding black sand.

iv. Stripping need to be done carefully to make sure the thickness of the stripped

black sand is consistent for the whole area.

v. For laboratory study, Mozley table analysis needs to be done carefully and

repeatedly to reduce errors in determining the concentration of heavy

minerals in the black sand sample.

vi. Evaluate the result of Magnetic Separator and High Tension Separator

analysis with larger amount of sample. These would reduce the errors in

determining the mineral in the black sand deposit.

85

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Kumar A., (May 2011) A review of seabed and placer mining deposits in India. Degree Dissertation Thesis, National Institute of Technology, Rourkela.

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Lecture notes for Astronomy 100– Tides (2011) [Online] Available from: http://flightline.highline.edu/iglozman/classes/astronotes/tides.htm [Accessed on 27th March 2013].

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Reyneke L., van der Westhuizen W.G. (2001) Characterisation of a heavy mineral-bearing sample from India and the relevance of intrinsic mineralogical features to mineral beneficiation. Minerals Engineering, Vol.14, no.11.

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Tyler R.M and Minnitt R.C.A. (March 2004) A review of sub-Saharan heavy mineral sand deposits: implications for new projects in southern Africa. In The Journal of The South African Institute of Mining and Metallurgy. South Africa. pp. 92.

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88

APPENDICES

Appendix A: Equipment used.

Plate A1: Oven for drying samples form the beach.

Plate A2: Mozley Table.

89 !

Plate A3: Rare Earth Magnetic Roll Separator.

Plate A4: High Tension Separator.

90 !

Plate A5: Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy

(SEM-EDX).

Plate A6: Stereo Zoom Microscope Kunoh Robo.

91 !

Appendix B: Data of gravity separation using Mozley table.

Table B1: Detail data for calculation of percentage of heavy mineral.

Date and tides Sample Mass Initial

(g)

Mass Concentrate

(g)

Mass Tailing (g)

Mass Concentrate and Tailing

(g)

Percentage Concentrate

(%)

Diff. initial and final mass (g)

Remarks

24.1.13 Initial sample

B1 - - - - - - 2 samples cannot be taken because located in the water.

D1 - - - - - - B2 129.60 52.22 74.79 127.01 41.11 2.59 D2 101.81 52.11 44.37 96.48 54.01 5.33 C3 100.46 32.83 64.71 97.54 33.66 2.92 B4 102.62 21.78 77.19 98.97 22.01 3.65 D4 129.65 36.04 89.73 125.77 28.66 3.88

24.1.13 Evening

B1 - - - - - - Only 2 samples are taken because day tides affected only these two points.

D1 - - - - - - B2 - - - - - - D2 - - - - - - C3 - - - - - - B4 87.02 40.92 42.88 83.80 48.83 3.22 D4 87.42 20.91 65.00 85.91 24.34 1.51

!

!

!

92 !


(g)

Mass Concentrate

(g)

Mass Tailing (g)


(g)


(%)


Remarks

25.1.13 Evening

B1 72.45 43.58 27.14 70.72 61.62 1.73 These samples are affected from the day tide on this day. At morning, samples are not taken.

D1 81.85 57.39 21.19 78.58 73.03 3.27 B2 85.24 38.50 44.11 82.61 46.60 2.63 D2 121.64 56.51 62.53 119.04 47.47 2.6 C3 92.77 37.05 51.68 88.73 41.76 4.04 B4 81.91 32.42 48.21 80.63 40.21 1.28 D4 107.53 38.89 65.47 104.36 37.27 3.17

26.1.13 Morning

B1 81.74 38.20 41.18 79.38 48.12 2.36 These samples are affected from the night tide on previous day.

B2 96.92 43.25 50.63 93.88 46.07 3.04 B4 90.62 22.77 67.09 89.86 25.34 0.76 C3 64.72 27.47 34.73 62.20 44.16 2.52 D1 69.21 36.96 28.66 65.62 56.32 3.59 D2 83.17 59.32 22.02 81.34 72.93 1.83 D4 118.88 29.74 87.33 117.07 25.40 1.81

26.1.13 Evening

B1 84.72 26.94 55.56 82.50 32.65 2.22

These samples are affected from the day tide on this day.

B2 87.16 21.58 63.22 84.80 25.45 2.36 B4 122.03 26.52 92.35 118.87 22.31 3.16 C3 118.80 34.17 82.20 116.37 29.36 2.43 D1 83.07 49.49 32.46 81.95 60.39 1.12 D2 62.89 39.05 22.60 61.65 63.34 1.24 D4 94.19 32.12 59.88 92.00 34.91 2.19

93 !


(g)

Mass Concentrate

(g)

Mass Tailing (g)


(g)


(%)


Remarks

27.1.13 Morning

B1 76.14 30.37 42.70 73.07 41.56 3.07 These samples are affected from the night tide on previous day.

B2 71.23 26.28 42.91 69.19 37.98 2.04 B4 59.93 21.83 37.65 59.48 36.70 0.45 C3 64.27 26.13 36.78 62.91 41.54 1.36 D1 68.20 45.28 22.30 67.58 67.00 0.62 D2 64.82 39.96 22.75 62.71 63.72 2.11 D4 64.92 21.31 42.06 63.37 33.63 1.55

27.1.13 Evening

B1 98.79 42.93 53.42 96.35 44.56 2.44

These samples are affected from the day tide on this day.

D1 74.90 36.86 37.50 74.36 49.57 0.54 B2 86.32 23.62 60.73 84.35 28.00 1.97 D2 100.16 29.29 70.84 100.13 29.25 0.03 C3 77.53 14.65 56.96 71.61 20.46 5.92 B4 60.94 13.93 43.63 57.56 24.20 3.38 D4 68.90 32.94 35.51 68.45 48.12 0.45

94 !

Appendix C: Overall beach levels average increments calculation.

1. Overall Average Increments (When stripping is done)

= !Sum!(Average!increments!when!stripping!is!done)How!many!times!stripping!is!done

= !0.9+ 0.6+ 0.8+ 0.84

= !0.78!Inch

2. Overall Average Increments (When no stripping is done)

= !Sum!(Average!increments!when!no!stripping!is!done)How!many!times!stripping!is!not!done

= !−0.1+ 0.2+ 0.13

= !0.1 Inch

Appendix D: Overall average concentration of heavy minerals in black sand

deposit calculation.

1. Overall Average Concentration (At particular tides)

= !Sum!(Average!concentration!at!particular!tides)Number!of!times!conducting!the!experiments! !×100%

= !35.89+ 36.59+ 49.71+ 45.48+ 38.34+ 46.02+ 34.887 !×100%

= !40.99!%!

2. Overall Average Concentration (At each sampling points)

= !Sum!(Average!concentration!at!each!sampling!points)Number!of!sampling!points !×100%

= !45.70+ 46.42+ 33.34+ 40.97+ 46.60+ 47.89+ 33.197 !×100%

= !42.01%

evaluation and planning of beach mining at pantai pasir hitam

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