EVALUATION AND PROCESSING OF ANDALUSITE MINERAL
FROM TERENGGANU, MALAYSIA
SENG SOPHEA
UNIVERSITI SAINS MALAYSIA
2015
EVALUATION AND PROCESSING OF ANDALUSITE MINERAL
FROM TERENGGANU, MALAYSIA
by
SENG SOPHEA
Thesis submitted in fulfillment of the requirements for the degree of Master of Science
November 2015
ACKNOWLEDGEMENTS
First of all, I am with love thank to my family for encouraging and supporting me since the beginning of my life until now and future.
I am strongly thankful to JICA-AUN/SEED-Net program for their financial support. Similarly, I am thankful to Universiti Sains Malaysia (USM), especially School of Material and Mineral Resources Engineering for a good cooperation during my
Master degree.
I would like to express my high sincere appreciation to my main supervisor
Assoc. Prof. Dr. Hashim bin Hussin for the advice, kind suggestions, and always support during the research. Same goes to my co-supervisor Assoc. Prof. Dr. Kamar
Shah Ariffin for all his help and suggestions.
Special thanks to dean, lecturers, technicians, and all the staff members in USM more importantly School of Material and Mineral Resources Engineering for warm guidance and help. And also, thanks to Department of Mineral Resources and
Geoscience, Malaysia for providing the samples for this study.
I would like to express my warm acknowledgement to all my Cambodian seniors, AUN/SEED-Net friends and friends in USM for their help and friendship that make my stay in USM such an unforgettable experience.
Thank you Seng Sophea November 2015
ii TABLE OF CONTENTS
ACKNOWLEDGEMENTS ...... ii TABLE OF CONTENTS ...... iii LIST OF TABLES ...... vii LIST OF FIGURES ...... ix LIST OF ABBREVIATIONS ...... xiv LIST OF SYMBOLS ...... xvi ABSTRAK… ...... xiii ABSTRACT...... xiv
CHAPTER 1 – INTRODUCTION 1.1 Introduction ...... 1 1.2 Malaysia Prospective on Andalusite ...... 2 1.3 Problem Statement ...... 3 1.4 Objective of Studies ...... 3 1.5 Overview of the Thesis ...... 4
CHAPTER2 – LITERATURE REVIEW 2.1 Introduction ...... 6 2.2 Geological Occurrence of Andalusite ...... 8 2.3 Mineralogy of Andalusite ...... 14 2.4 Physical and Chemistry Properties of Andalusite ...... 16 2.4.1 Physical Properties ...... 16 2.4.2 Chemistry of Andalusite ...... 17 2.5 Mining Technology of Andalusite ...... 20 2.6 Application of Andalusite in Industry ...... 23 2.6.1 World Production of Andalusite ...... 25 2.7 Geology of Terengganu...... 24 2.7.1 Stratigraphy of South and Central Terengganu ...... 27
iii 2.7.2 Structure and Deformation in Terengganu ...... 27 2.7.3 Geology of Sungai Cerul ...... 29 2.7.4 Geology of Kemasik ...... 29 2.7.5 Geological study of andalusite ...... 30 2.8 Andalusite Processing ...... 32 2.9 Microwave Treatment ...... 34 2.9.1 Introduction ...... 34 2.9.2 Basic concept of Microwave ...... 37 2.9.3 Application of Microwave assisted Liberation ...... 39
CHAPTER 3 – MATERIALS AND METHODS 3.1 Introduction ...... 41 3.2 Raw Materials ...... 43 3.3 Ore Sampling ...... 43 3.3.1 Site sampling ...... 44 3.3.2 Laboratory sampling ...... 44 3.4 Characterization of Raw Materials...... 44 3.4.1 Mineralogical analysis ...... 44 3.4.1(a) Thin Section Preparation ...... 44 3.4.1 (b) XRD Analysis ...... 46 3.4.1 (c) Scanning Electronic Microscopy (SEM) and EDX ...... 47 3.4.2 Chemical Analysis ...... 48 3.4.2 (a) X-ray Fluorescence Spectrometry (XRF) ...... 48 3.4.2 (b) Loss on Ignition (L.O.I) Determination...... 48 3.5 Andalusite Production ...... 49 3.5.1 Crushing ...... 49 3.5.2 Grinding Process ...... 50 3.6 Microwave Treatment ...... 51 3.6.1 Dry Sample Experiments ...... 52 3.6.2 Wet Sample Experiments ...... 52 3.6.3 Andalusite Production from Microwave Treatment ...... 53
iv
CHAPTER 4 – RESULTS AND DISCUSSION 4.1 Andalusite Location in Malaysia ...... 54 4.2 Physical Appearance ...... 55 4.3 Characterization Raw Material ...... 60 4.3.1 Mineralogical and Petrography Analysis ...... 60 4.3.1(a) Ore Microscopy ...... 60 4.3.1 (b) Thin Section Results ...... 61 4.3.1 (c) X-Ray Diffraction Result ...... 64 4.3.1 (d) Scanning Electron Microscopy Results ...... 66 4.3.2 Chemical Characterization ...... 69 4.3.2 (a) XRF Result ...... 69 4.3.2 (b) Loss on Ignition (L.O.I) ...... 71 4.4 Liberation and separation of andalusite ...... 71 4.4.1 Primary Liberation Grade ...... 74 4.5 Effect of Rotational Speed of Rod mill ...... 75 4.5.1 Rotational speed at 10 rpm/40 min ...... 75 4.5.2 Rotational speed at 20 rpm/40 min ...... 76 4.5.3 Rotational speed at 30 rpm/40 min ...... 76 4.6 Effect of Microwave treatment ...... 78 4.6.1 Dry Sample ...... 79 4.6.1 (a) Dry sample heated in high temperature ...... 79 4.6.1(b) Dry sample heated in medium temperature ...... 81 4.6.1 (c) Dry sample heated in low temperature ...... 82 4.6.2 Wet Sample sock for 30min in water ...... 83 4.6.2(a) Wet sample treated in high temperature ...... 83 4.6.2 (b) Wet sample treated in medium temperature ...... 85 4.6.2 (c) Wet Sample treated in low temperature ...... 87 4.7 Liberation and Separation ...... 88 4.7.1 Microwave treatment production grad ...... 90
v CHAPTER 5 – CONCLUSIONS AND FUTURE WORK 5.1 Conclusion ...... 91 5.1.1 Raw Materials Characterization ...... 91 5.1.2 Grindability of andalusite bearing rock ...... 92 5.1.3 Grindabilty of andalusite bearing rock after the microwave treatment .... 93 5.2 Suggestion for Future work ...... 94
REFERENCES ...... 95
LIST OF PUBLICATIONS ...... 100
APPENDICES
APPENDICE A APPENDIX A1 APPENDIX A2 APPENDICE B APPENDIX B1 APPENDIX B2
vi
LIST OF TABLES
Page
Table 2.1 Andalusite properties (Perepelitsyn et al., 2013) 17
Table 2.2 Major Andalusite producer (Feytis, 2011) 24
Table 2.3 Summary of mineral heating rate (Walkiewicz, 1988) 35
Table 2.4 The Effect of microwave heating temperature of various 36 minerals at 500 W, 2450 MHz (Chunpeng et al., 1990)
Table 2.5 Frequency allocation for ISMI applications 38 Table 2.6 Minerals that is transparent to microwave irradiation at 39 2450 MHz, 150W, 5 min exposure time (Chunpeng et al., 1990)
Table 4.1 Characterization Study 54
Table 4.2 Grinding- Sungai Cerul Sample 55
Table 4.3 Microwave Treatment with Home Microwave 55
Table 4.4 Chemical composition of andalusite bearing rock from 70 Sungai Cerul
Table 4.5 Chemical composition andalusite crystal from Sungai Cerul 70
Table 4.6 Chemical composition of andalusite bearing rock samples 71 from Kemasik area
vii Table 4.7 Chemical analysis of andalusite grade before crushing and 74 sieving
Table 4.8 Chemical analysis of andalusite grade after crushing and 75 sieving
Table 4.9 Grade of andalusite bearing rock before separation 90
Table 4.10 Grade of Andalusite bearing rock after separation 90
viii
LIST OF FIGURE
Page
Figure 1.1 Yearly import andalusite, kyanite and sillimanite in US dollar 2 (UNComtradeDatabase, 2011)
Figure 2.1 Andalusite occurrences in British Columbia (Simandl et al., 12 1995)
Figure2. 2 Andalusite with cross section called chiastolite 14
Figure 2. 3 Formation of chiastolite in andalusite crystal 14
Figure 2.4 Chemical structure of andalusite (Botha, 2010) 18
Figure 2.5 Phase diagram for Kyanite- andalusite and andalusite- 19 Sillimanite (Shackelfard and Doremus, 2008)
Figure 2.6 Geological map in Terengganu area (Extracted from 26 Geological of Penninsular Malaysia) (Hutchison and Tan, 2009).
Figure 2.7 (a)Major faults in Peninsular Malaysia. (b) Regional N-S faults 30 of Terengganu, Peninsular Malaysia: Besut, Kampung Buluh belt and Ping-Teris. The base is from the "Mineral Distribution Map of Peninsular Malaysia" published by the Geological Survey of Malaysia (8th edition 1988; original scale 1:500,000)
Figure 2.8 Schematic Flowsheets for plant operation on coarse and fine 33 crystal andalusite (Overbeek, 1989)
Figure 3.1 Flow sheet of experimental work 42
ix
Figure 3.2 location of andalusite sample samples in Terengganu, 43 Malaysia.
Figure 3.3 Equipment used for thin Section. (a) cutting machine(Buhler 56 Petro-cut) (b) Trimming machine (Buhler Petro-thin). (c) Grinding machine. (d) Finishing thin section sample
Figure 4.4 Laboratory Jaw crusher 50
Figure 3.5 (a) Pascal rod mill, (b) rods in different size 51
Figure 3.6 Treatment process. (a) dry sample, (b) wet sample, ( c) sample 53 placed in microwave, (d) Home microwave
Figure 4.1 Selected andalusite bearing rock samples from Sugai Cerul (a) 56 Large crystal of andalusite bearing rock presented in slightly weathered rock. (b) Mica can easily be seen in highly weathered rock
Figure 4.2 Outcrop of andalusite bearing rock in Kemasik 57
Figure 4.3 The andalusite deposit at kemasik area. Various quartz veins 58 presented in the rock from 2 cm to 5 cm width. Rocks are highly weathering.
Figure 4.4 Selected rock specimens from Kemasik. (a) Sandstone (b) &(c) 59 Meta sandstone with numerous micaceous muscovite which strongly altered (d) Phyllite, made up mostly of very fine grain mica which is muscovite.
Figure 4.5 The crystal of andalusite under optical microscopy with the 60 magnification X70. An: Andalusite, Chl: chiastolite.
Figure 4.6 The irregular of andalusite crystal under optical microscopy 61 with the magnification X70.
x Figure 4.7 Photomicrographs illustrating andalusite in thin section: (a) 62 strongly foliated phyllite with numerous muscovite, sericite and biotite (X20), (b) mineral andalusite embedded in phyllite (X50).
Figure 4.8 Photomicrographs illustrating andalusite under thin section: (a) 64 XPL(X20) uneven distribution andalusite (b) XPL (X100), (c)PPL(X100).
Figure 4.9 Representative XRD diffractogram of representative sample 65 from Sungai Cerul.
Figure 4.10 Representative XRD diffractogram of representative sample 65 from Kemasik area.
Figure 4.11 SEM-EDX analysis of andalusite with the presence of 66 associated mineral. (An: andalusite, Crd: corundum, Mz: monazite).
Figure 4.12 SEM-EDX analysis of andalusite with the presence of 67 associated mineral. (An: andalusite, Crd: corundum, Ru: rutile, Mz: monazite).
Figure 4.13 SEM-EDX analysis of andalusite with the presence of 69 associated mineral. (An: andalusite, , Ru: rutile, Mz: monazite, Ha: halite, Qu: quartz).
Figure 4.14 Sample after crushed by Jaw crusher. 72
Figure 4.15 Andalusite crystal after crushing and sieving procedure. (a) 73 andalusite crystal passing the sieve 6.33 mm, (b) andalusite crystal passing the sieve 2.8 mm.
Figure 4.16 Particle size distribution of andalusite bearing rock after 75
xi grinding
Figure 4.17 Particle size distribution of andalusite bearing rock after 76 grinding
Figure 4.18 Particle size distribution of andalusite bearing rock after 77 grinding
Figure 4.19 Particle size distribution of andalusite bearing rock after 78
grinding with difference rotation speed.
Figure 4.20 Optical microscopy of andalusite crystal in their matrix before 79 treatment by microwave (X70).
Figure 4.21 sample before treat by Microwave 79
Figure 4.22 The andalusite sample after treated in high heat by microwave. 80 (a) Sample burst into small pieces. (b) The boundary of andalusite and matrix (X50). (c) Microwcrack along the matrix area (X50).
Figure 4.23 Sample before treated by Microwave. 81
Figure 4.24 The andalusite sample after treated in medium heat by 81 microwave. (a) Sample broke along the interface of crystal and matrix. (b) Andalusite crystal under transmit light microscopy (X50).
Figure 4.25 Sample before treated by microwave 82
Figure 4.26 Sample condition after treated by microwave in low heat. 83 Photograph of breaking sample. (a) & (b) The fracture along the interface of andalusite crystal and matrix (X30)
Figure 4.27 Wet sample before treat by Microwave 84
xii
Figure 4.28 The andalusite sample after treated in high heat by microwave. 85 (a) Showed the breaking along the boundary of crystal and surface. (b) The microcrack in the ore. (c) Unbreak surface of the ore
Figure 4.29 Sample sock in water for 30 minute before treated by 85 microwave
Figure 4.30 The andalusite sample after treated in medium heat by 86 microwave. (a) Rock sample broke along the interface of the crystal and matrix. (b) Micro cracks at the interface between andalusite crystal and matrix
Figure 4.31 Sample before treated by microwave 87
Figure 4.32 Crack along the interface between andalusite crystal and 88 matrix
Figure 4.33 The production of andalusite after microwave treatment with 89 +6.33 mm
Figure 4.34 The production of andalusite after microwave treatment 89 with +2.8mm
xiii LIST OF ABBREVIATION
An Andalusite
ATM American Testing Materials
Crd Corundum
DMS Dense Media Separation
EDX Energy dispersive X-ray
ENE East North-East
FOB Free on board
Ha Halite
ISMI International Sematic Manufacturing Initiative
JMG Minerals and Geoscience Department
L.O.I Loss on Ignition
Mz Monazite
NNW North North-West
NS North-South
PPL Plane-polarized light
Ru Rutile
SEM Scanning Electron Microscope
xiv SG Specific Gravity
SSE South South-East
TPA Tonnes per annum
XPL Cross-polarized light
XRD X-ray Diffraction
XRF X-ray Fluorescence
xv LIST OF SYMBOLS
% percentage
°C degree Celsius km kilometer km2 kilometer cube m meter mm millimeter cm centimeter
µm micrometer g gram g/cm3 gram per centimeter cubed rpm round per minute
Wt% weight percentage
Al2O3 Aluminum oxide
Fe2O3 Magnetite
Al2SiO5 Sillimanite Mineral (Andalusite, Kyanite and sillimanite)
SiO2 Silicon dioxide
ρ density
xvi Kbars kilobars
GHz gigahertz
MHz megahertz kW kilo watt kv kilovolt mA miliampere
xvii PENILAIAN DAN PEMPROSESAN MINERAL ANDALUSIT DARIPADA TERENGGANU, MALAYSIA
ABSTRAK
Dalam penyelidikan ini sampel daripada dua kawasan iaitu Sungai Cerul dan Kemasik, Terengganu telah dikaji. Mineral andalusit dalam bentuk kristal jelas dapat dilihat dalam julat saiz 2 cm to 5 cm tertanam atau tersimen bersama filit dalam sampel yang diperolehi dari Sungai Cerul. Manakala kehadiran mineral andalusit sukar untuk dilihat dalam sampel yang diperolehi dari Kemasik. Gred mineral andalusit dalam sampel Sungai Cerul menunjukkan ia mengandungi lebih kurang 49.13% Al2SiO5 manakala analisa ke atas gred kristal andalusit mendapati ia mengandungi sehingga
73.35 % Al2SiO5. Disebabkan peratusan andalusit yang tinggi, deposit ini mempunyai potensi untuk dieksploitasi. Sampel yang diperoleh dari Kemasik terjadi dalam persekitaran geologi yang sama dengan sampel dari Sungai Cerul namun andalusit tersebar di dalam filit sebagai batuan perumah. Walau bagaimanapun, kejadian mineral andalusit di Kemasik telah terjejas oleh luluhawa yang tinggi serta perubahan sekeliling. Sampel dari Kemasik, tiada bentuk kristal andalusit yang tertentu terdapat di dalam batuan perumah dan gred Al2SiO5 yang terkandung adalah kira-kira 40.81 %. Di samping itu, ciri-ciri fizikal andalusit yang secara perbandinganya sukar untuk diproses secara fizikal maka mendapan ini dikategorikan sebagai tidak berpotensi buat masa ini. Eksperimen pengisaran yang dilakukan, menggunakan sampel andalusit dari Sungai Cerul, menunjukkan bahawa kelajuan putaran rod yang optimum bagi membebaskan mineral andalusit dari batuan perumah adalah pada kelajuan 20 putaran per minit (rpm) selama 40 minit. Pembebasan dan pemisahan andalusit dari batuan perumah berjaya meningkatkan gred andalusit sekitar 13.14% Al2SiO5. Dengan rawatan gelombang mikro, pembebasan telah bertambah baik dan meningkat sehingga 17.44 % Al2SiO5. Selain peningkatan gred andalusit, masa pengisaran juga berkurangan dari 40 minit ke 15 minit dengan peningkatan pembebasan daripada 60% kepada 70%. Di samping itu, rawatan gelombang mikro dengan suhu yang rendah dalam keadaan basah menunjukkan hasil yang baik bagi pemecahan antara muka.
xviii EVALUATION AND PROCESSING OF ANDALUSITE MINERAL FROM TERENGGANU, MALAYSIA
ABSTRACT
In this research, two andalusite bearing rock samples from Sungai Cerul and Kemasik, Terengganu areas were studied. Coarse andalusite crystals in range of 2 cm to 5 cm in length were found embedded or cemented with phyllite in sample from Sungai Cerul. Whereas, the presence of andalusite crystal in the andalusite bearing rock sample from Kemasik was hardly to be observed. Grade of andalusite bearing rocks from
Sungai Cerul indicated that it is contain approximately 49.13% Al2SiO5 and analysis on the andalusite crystal found that it contains up to 73.35% Al2SiO5. Due to the high percentage of andalusite, this deposit has the potential to be exploited for its value. The samples from Kemasik occurred in similar geological environment as in Sungai Cerul which is disseminated in phyllite as host rock. Though, the occurrence of andalusite mineral in Kemasik was affected by high weathering and alteration. Compared to samples from Sungai Cerul, the andalusite bearing rock from Kemasik have no specific andalusite crystal shape in host rock and the grade of Al2SiO5 is about 40.81% Al2SiO5. Due to the physical properties of andalusite from Kemasik is comparatively difficult to be processed by physical methods this deposit was considered not viable for the time being. The experimental works on grinding performance on andalusite bearing rock from Sungai Cerul indicated that the optimum rotational speed of the rod mill to liberate the andalusite mineral from the host rock is at 20 rpm for 40 minutes. The liberation and separation of andalusite from the host rock managed to improve the grade of andalusite approximately 13.14 % Al2SiO5. With the microwave treatment, the liberation has been improved and increased the grade of andalusite up to 17.44 % Al2SiO5. Grinding time was also reduced from 45 minutes to 15 minutes with better liberation from 60% to 70% when microwave treatment was applied. In addition, the microwave treatment with low temperature in wet condition show a good result of the breaking the andalusite crystal interface.
xix CHAPTER 1
INTRODUCTION
1.1 Introduction
Sillimanite group mineral (Al2SiO5 or Al2O3.SiO2) such as andalusite, kyanite and sillimanite is a hope of new material for industrial mineral. The most important mineral that use in the production of advanced refractory material was the orthorhombic crystal andalusite (Burt and Ross, 2006). When firing these minerals at 1380 °C its will transform to mullite (3 Al2O3.2SiO2) with low expansion (5%) (Beuvelet et al., 1996).
These mineral become an interested material for many reasons:
- Provide high thermal stabilities due to low thermal expansion
- Low resistance to creep, and low of deformation in high temperature under load.
- Perform a good resistance to the action of molten metal and good resistance to
slag.
South Africa had been known as the world largest reserve and the biggest andalusite production in the world which is concentrated in various localities around the Bushveld
Complex (Botha, 2010). Other than South Africa, the countries that also produce andalusite are France, China, Peru, the United States and Spain (Simandl et al., 1995a,
Feytis, 2011).
1 1.2 Malaysia Prospective on Andalusite
Andalusite consider as new mineral to Malaysia which is no exploitation yet.
Every years Malaysia imported a significant value of sillimanite group mineral such as andalusite, kyanite, and sillimanite to support the demand of industries. In 2005 the quantity of import is 653 060 tons and continue increase to 1 240 520 tons in the year
2008. In 2009 the amount of import decrease in 2009, however the demand increase again in 2010 up to 1 444 782 tons and 1 006 000 tons in 2011. Figure 1.1. shows quantity and price of sillimanite mineral imported from 2005 to 2011. Since 2005 the value of imported who gradually increase from US$ 200 000 to US$ 700 000 in the years 2010. However, the value slightly decreased to US$ 500 000 in the year 2011
(UNComtradeDatabase, 2011).
Yearly Import Silimanite Group Mineral in Malaysia 800,000 700,000
600,000
500,000 400,000
300,000 Dollar (USD) Dollar 200,000 100,000 0 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Year
Figure 1.1: Yearly import andalusite. kyanite, and sillimanite in US dollar (UNComtradeDatabase, 2011).
2 1.3 Problem Statement
Andalusite is one of the best natural resources of mullite among aluminosilicate material, which is formed at comparatively low temperature. Based on the huge advantage of this mineral for industrial application, andalusite becomes a crucial mineral for exploration and exploitation. Although, numerous research papers published about andalusite occurrence, mining and processing worldwide, but the information of this mineral in Malaysia very limited. Base on the existing report in south-east Asia (Sa and
Boom, 2003), there are abundant of andalusite, group of sillimanite mineral occurrence in Terengganu area. However, comprehensive report or recent study to evaluate and process this mineral scientifically in the aspect of economic evaluation to identify its quality and uses is not yet done by anybody in Malaysia. Therefore, this study is importance to give some input and idea about the qualities and beneficiation methods that can be used to prepared final product. This will save Malaysia money on importing andalusite from foreign country worth US$ 158 201 (in the year 2011)
(UNComtradeDatabase, 2011).
1.4 Objective of Studies
The aims of this project are to provide scientific information regarding the characterizations and the beneficiation of Malaysian andalusite. The main objectives of this research are:
i. To characterize the quality of Malaysian andalusite
3 ii. To evaluate the potential of Malaysian andalusite
iii. To determine the beneficiation of the andalusite ore to produce clean
andalusite concentrate.
1.5 Overview of the Thesis
This thesis has been divided into five parts. Chapter one, provide general information related to problem statement and the objective of this research.
Chapter Two, present several information and knowledge related to andalusite around the world and in Malaysia such as geological occurrence, production, price, industrial application and the advantage of microwave treatment assisted grinding.
According to the numerous advantage of andalusite, this mineral is a key factor to support Malaysian economy.
The methodologies and equipment used in this research revealed in Chapter
Three. In this research samples were collected from two different locations in
Terengganu. The characterization of this samples was investigated on mineralogical study by using thin section, X-ray diffraction, scanning electron microscopy, and chemical composition analysis by using X-ray fluorescence. The primary liberation included crushing, grinding and sieving. Furthermore, microwave treatment method had been applied for improving the liberation and separation.
4 Chapter Four provided the data from experimental work with the discussion associated with the quality of andalusite in Terengganu, Malaysia. On top of that, the improvement from liberation and ore treatment also discussed.
Chapter Five gives the conclusion of the studies and suggestion of future work to be done.
5 CHAP TER 2
LITERATURE REVIEW
2.1 Introduction
The sillimanite group mineral such as andalusite, sillimanite, and kyanite are naturally occurring as anhydrous aluminum silicate mineral that has the same chemical formula (Al2SiO5), but different in crystal structure (Overbeek, 1989). These minerals are very important raw material for the ferrous and non-ferrous industries in order to produce superior high grade alumina. Meanwhile, andalusite provide a good beneficiation related to the low relative density, lower volume expansion on being heated, and can be produced with a simple mining and concentration procedure at its natural grain size (Overbeek, 1989).
In the early the world production of sillimanite group mineral was as 690 000 tons which is 115 000 tons kyanite; 315 000 tons andalusite; 25 000 tons sillimanite and
235 000 tons of synthetic mullite in several form (Sweet. et al., 2006). The world largest resources and producer of andalusite is South Africa. The other countries that produce andalusite are France, China, Peru (Botha, 2010)and the United States (Simandl et al.,
1995a). In France, China and Peru the andalusite deposits occur in dynamic metamorphic areas, though most of the deposits of South African are related to thermal metamorphism (Botha, 2010). The profitable concentration of andalusite from South
Africa and France are various from 53% Al2O3 to 60% Al2O3 and from 0.8 to 1.5%
6 Fe2O3. In any refractory application iron is the most harmful impurity. According to the survey in July of 2000, the price of bulk shipment FOB (Free on board) in South Africa varied from US$171 to US$200/ton for a 2 000 ton shipment (Simandl et al., 1995b).
In South Africa most of andalusite deposits are mined by open cast methods by using face development and bench mining procedures. Technically, simple technique such as rippers, scrapers, or face-shovels had been applied for an ore-loosening operation. As the mining proceeds and the ore become harder at depth, blasting technique is indeed been applied to loosen the ore (Overbeek, 1989). The andalusite sands in the Marico District of the Transvaal, South Africa are processed by heavy media separation and high intensity magnetic separation methods (Sweet. et al., 2006).
This process relies on the physical characteristics of the ore such as (a) shales properties and natural cleavage between crystal and shale, (b) differentiation in relative density of andalusite and shale, (c) differentiation of magnetic susceptibility of andalusite (non- magnetic) and the impurities iron. Near Glomel in Brittany, France, DAMREXC used vertical blasting method and hydraulic percussion lump breaker to loosen the ore
(Overbeek, 1989).
Andalusite based refractories have historically been used in Europe, South Africa and the Far East, but there are very limited used in America due to the expensive delivery cost and availability of other local materials. Though, there has been an increase in the use of andalusite in North America. Andalusite, sillimanite and kyanite are important minerals that transform to mullite (Al6Si2O13) when exposed to high temperature. As long as the volume expends, silica is liberated. Mullite is a very stable
7 material which the ability to stand in high heat and resistance to chemical and physical erosion, so it becomes the ideal material use in refractories production (Louw, 2011). It had been used extensively in the manufacture of high-alumina refractories, and ceramic industries. It is also preferable in steel industry due to the good refractoriness, good creep-resistant, load-bearing properties at high temperature, resistance to thermal shock and resistance to chemical attack and abrasion (Beuvelet et al., 1996). The combination of coarse and fine grained andalusite materials provided the ideal lining for the inside of steel furnaces, smelters, kilns, incinerators and reactors. The end product found inside smelters can withstand temperatures of up to 1400°C to 1600°C (Louw, 2011).
Sometime the andalusite crystal had been found in large single crystal form at the quality level suitable for gemstone. Minas Gerais, Brasil is the place where a beautiful green andalusite commonly found, and also can be achieved at gem and mineral show around the world (Shackelfard and Doremus, 2008).
2.2 Geological Occurrence of Andalusite
Andalusite most commonly found in low pressure associate with metamorphic environment. The temperature of andalusite formation is approximately 550 °C and above under two possible mechanism such as dynamic metamorphism and thermal metamorphism. Dynamic metamorphism associated with continent plate of oceanic and continental plate collision zone. Andalusite in the Northern Cape of Namakwa metamorphic belt occurs as a small lenses and narrow zone, which is not economic to be mine. Thermal metamorphism is a contact metamorphism where the source of heat is required, happened by magmatic intrusion that elevates the temperature surround the
8 rock until the certain requirement for andalusite to form. This mechanism occurs in
South Africa as the metamorphic aureole of Bushveld complex which is the most economically viable andalusite cover the area of 66 000 km2 (Botha, 2010). In the northern-western Bushveld, Thabazimbi, Marico, eastern Bushveld, Chuniespoort,
Penge and Lydenburg (Overbeek, 1989) andalusite occurs in hornfels and schists or as associated alluvial deposit. Thabazimbi, Lydenburg and Penge are currently being mined. Another deposit that occurs in south-western limb of the Bushveld complex,
Groot Mariko also provided an economical benefit, but it is not recently being exploited yet.
The Bushveld complex intrusion into Pretoria Group system took place around
1.6 billion years ago. Coarse grained and silt material are the most availability in the
Pretoria Group system. The shales of the Pretoria Group, Timeball Hill, and Silverton formation were rich in alumina. On the other hand, during the emplacement of the
Bushveld complex made the Pretoria Group system deformed which dips toward the center of the Bushveld complex. Due to this new geometry assisted in the exposure of the andalusite bearing schist to the element. This action made the area surround the
Bushveld complex mostly are valley and hill landscape. The hardness of host rock is a critical factor for andalusite recovery (Botha, 2010).
Groot Marico in Zeerust area, western Bushveld complex can be classify into two type of deposit. The first deposit is the metamorphosed shales of the Dasport stage and the second is the alluvial sands of the rivers that drain these shales. The concentrates
9 assaying of metamorphose shales deposit is 59% Al2O3 and less than 1% Fe2O3, where the grade of alluvial deposit less than 55% Al2O3 and more than 1.5 % Fe2O3.
In the Thabazimbi northwestern Bushveld andalusite occurring in a soft and highly weathered mica hornfels along the Timeball Hill shale. The formation of shales in this area is the youngest part of meta-sedimentary basin call Transvaal system. The main factor control the alteration of the Pretoria shales to andalusite and chiastolite bearing hornfelses is the heat in the middle of the sedimentary basin known as Bushveld
Complex. Al2O3 grade is more than 59%, Fe2O3 is less than 1% and up to 15% andalusite in the host rock (Botha, 2010).
In Brittany, France andalusite occurs in a matchstick sized, crystals embedded in a fine grained black groundmass composed of biotite, hornblende, muscovite, and feldspar. The andalusite disseminated and constitutes approximately 20% of rock. Rock in this area poorly exposed, and the geology of the occurrence is not well understood.
This deposit is being mined by DAMREC which has been active since 1969 (Sweet. et al., 2006).
Near Canso, Nova Scotia had been discovered a large andalusite deposit. The size of andalusite crystal approximately 1.3 cm to 2.5 cm in cross section, crystal evenly disseminated in host rock as large porphyroblasts. The andalusite up to in host rock. The matrixes mostly are muscovite, garnet and feldspar. In the andalusite crystal there are a finely magnetic and muscovite about 10% which make the beneficiation not practical
(Sweet. et al., 2006).
10 The Piedmont Mineral company mined andalusite-pyrophyllite-sericite in North
Carolina near Hillsborough, and now become a division of Resco Product. The pink andalusite around 15% to 20% disseminated in the ore, and the principal groundmass are pyrophyllite and quartz. The andalusite mined together with pyrophyllite and calcined in part by nature which is typically used only for preparation calcined materials. The consumer of the product is Resco Product for manufacture of kiln car refractories, plastic and castable refractories, firebrick, ramming and gunning mixes (Sweet. et al.,
2006).
Andalusite had been found coexists with kyanite and sillimanite at Goat
Mountain deposit in Idaho (Abbott and Prater, 1954). This deposit included many deleterious impurities which make the separation method not practical in the test apply so far. Even the deposit extremely large, there are no commercial exploitation due to the difficulties of beneficiation (Potter, 1985).
In early 1991, Ramsgate Resources Ltd was discovered the occurrences of andalusite bearing chorite-biotite schist in Western Australia‟s Eastern Goldfield. The andalusite occurs as disconnected crystals in length from 0.5 to 20 cm in the metamorphosed aluminous metasedimentary rock. According to (Anon, 1989) it is a very high quality andalusite, equal or the same as South African andalusite.
As show in Figure 2.1, more than 23 andalusite occurrences known in British
Columbia (http://www.em.gov.bc.ca/Mining/Geolsurv/Minfile/search/). Among those occurrences the Omineca area, Coast and Insular belts is a regional metamorphism (low-
11 pressure, high-temperature) which is a good geological potential for andalusite deposit wherever the existent of aluminous protoliths. Unfortunately, andalusite was converted to sillimanite or kyanite due to a later high-temperature metamorphic overprint, hydrated mineral such as muscovite.
Figure 2.1: Andalusite occurrences in British Columbia (Simandl et al., 1995a)
This belt consists largely of metamorphic and intrusive rock (Simandl et al.,
1995a) and it is described in the southern Omineca Belt on the west side of Kootenay
Lake, near Victor Lake, near Eagle Pass Mountain, and north of Revelstoke along the
Columbia River. In the northern Omineca Belt present the andalusite bearing rock, which is occur within basement gneiss near the Ecocene Balourdet pluton in the sifton
Rang, and in rock 30 km to the north (Evenchick, 1988). Close to the confluence of the
12 Turnagain and Cassiar rivers also present another occurrence where the andalusite porphyroblasts around 3 to 4 centimeters long are partially retrograded to muscovite.
Metasediments with the contact of an Early cretaceous pluton acted as a hosted of this occurrence (Gabrielse et al., 1991).
Granites and greenschist to granulite facies metamorphic rocks are mostly found in the Coast Belt. From the edge of the Coast Belt along the northwest trend there are an occurrence of andalusite in the condition low pressure, high temperature metamorphic prevailed during Mid to Late Cretaceous deformation and magmatism (Rushmore and
Woodsworth, 1994). The estimation of the metamorphic condition was at 3.5 kbars and
500 to 650 ºC.
In Norway andalusite found in Caledonides and Oslo Igneous province with the association of plutonic complexes intruding low-grade metamorphic rock. The andalusite-cordierite hornfelses are formed contact between Cambrian-Early Ordovician black shales (alum shales) and Permian granitic plutons. The thickness of andalusite zone in the Eiker-sands-vaer is about 10m and contain hardly more than 7% of coarse grained chiastolite crystals which is consider as sub-economic (Ihlen, 2000). The eastern part of the Trondheim Nappe complex in the central of Norwegian Caledonides presents the most prominent andalusite that is contact-metamorphic aureole of the Fongen-
Hyllingen and Øyungen gabbro complexes (Birkeland and Nilsen, 1972). The andalusite schists that abundant is about 5-18 mm long and 2-8 mm wide (Vogt, 1941), it is appear as a fine grained, brownish-grey mica schists with the characteristic knobby appearance
13 on weather surface with the contents of andalusite in the ore around 20% (Birkeland and
Nilsen, 1972).
2.3 Mineralogy of Andalusite
Andalusite mostly entrapped with carbonaceous or clay materials during crystal growth created the formation of chiastolite. The pattern usually cross shaped, and it is normally appear when a crystal cut as show in Figure 2.2. In Figure 2.3 showed the performance of chiastolite grows in the crystal of andalusite. Chiastolite forms due to the entrapment of carbonaceous material during the crystal grow (Deer et al., 1992).
Chiastolite
Figure 2.2: Andalusite with cross section called Chiastolite (ebaumsworld.com, 2013)
Figure 2.3: Formation of chiastolite in andalusite crystal (Botha, 2010).
14 Mineral inclusion such as biotite that substitute in chiastolite in a cruciform pattern cannot be removed during beneficiation, which is effect the final product grade.
When the pressure or temperature lead to the development of the andalusite crystal, the crystal start back on a retro-grade metamorphic path back to the original state. This mechanism leads the formation of alteration rims of sericite and muscovite on the crystals. In some case the substitution of sericite and muscovite lead to “light” andalusite crystals that cannot be recover during beneficiation. The friability of the andalusite crystals determine by the retro-grade metamorphism so the size of the crystal recovered
(Botha, 2010).
Andalusite also found in the argillaceous rock in the form of aureoles around igneous intrusion, and normally associated with cordierite. In the early stage of such metamorphism andalusite occurs as anhedral grains but rapidly acquires a prismatic outline, pushing aside enclosed foreign matter to from the chiastolite pattern: in more advance grade the andalusite become clear of inclusions. Under the condition of higher temperature and pressure it may become unstable and invert to its polymorphs sillimanite or kyanite. Andalusite and cordierite are frequently found in regionally metamorphosed areas where there appears the relaxation of shear stress, in the Banff area of north-east Scotland (Mitchell and Harrison, 1997).
15 2.4 Physical and Chemistry Properties of Andalusite
2.4.1 Physical Properties
Andalusite is an orthorhombic mineral which all Si4+ cations are in four-fold
2+ coordination with O anions. In orthorhombic structure, the AlO6 octahedra chains are linked by SiO4 tetrahedra and AlO5 polyhedra alternate within the structure (Shackelfard and Doremus, 2008).
The refractive indices and specific gravity are increased or decreased depend on the amount of ferric iron and manganese entry to the structure. Fe and Mn contents also effect the color and pleochroism of the mineral, the pink and red varieties present Fe whereas the green crystal present. When the initial growth of the crystal incapable to free itself from the inclusions may cause the impurities concentrate at the center of each crystal. Moreover, there are the representing the trace of the prism edges as the crystal along the diagonals, in this case the other impurities being brushed aside to the edges by the crystal growth which was the most effective in direction perpendicular to the prism faces (Deer et al., 1992).
Among the aluminum silicate mineral, andalusite has the lowest specific gravity which is approximately 3.18, and the hardness slightly higher than kyanite and sillimanite which is about 7.5 (Sweet. et al., 2006).
16 Table 2.1: Andalusite properties (Perepelitsyn et al., 2013)
Properties Andalusite
Crystal chemistry formula Al Al [SiO4] O Syngony Rhombic Refractive Index Ng 1.63-1.6 Nm 1.63-1.64 Np 1.62-1.64 True density, g/cm3 Ng 1.63-1.65 Nm 1.63-1.64 Np 1.62-1.64 Decomposition temperature, °C 1350-1400 Volumetric expansion with regeneration, % 3-6
2.4.2 Chemistry of Andalusite
The chemical composition of andalusite is Al2SiO5 which theoretically contain
62.92% of Al2O3 and 37.08% of SiO2. Ferric iron and manganese are the only ions that present noticeable, this replacement is normally small and Fe2O3 contain in andalusite less than 2%. Substitution of Al6+ by Fe3+ gives pinkish color andalusite and the substitution with Mn3+ gives green color (Deer et al., 1992). The structure of andalusite is nesosilicate where (SiO4)4- linked with Al5+ and Al6+. These structure performances make the crystal lattice of andalusite become high symmetry and contributing factor to the hardness. Figure 2.4 show the crystal structure of andalusite. The structure consists of edge-linked AlO6 octahedra that are parallel to the z-axis. These chains are linked by
Si coordinated by four oxygens, and the Al coordinated by five oxygens.
17
Figure 2.4: Chemical structure of andalusite (Botha, 2010)
The synthesized of andalusite can be done by using kaolinite or using Al2O3+
SiO2 at 450-650 °C with the water-vapour pressure between 0.6 and 2.0 kbar (Deer et al., 1992). At pressure 1 atm, there are no phase diagrams of the familiar binary alumina- silica of sillimanite group mineral. It is present only a single alumino-silica which is mullite, 3Al2O3.2SiO2 (ideal composition 71.79 wt% alumina and 28.21 wt% silica).
The geological of sillimanite mineral formed at high pressures and elevated temperatures which make the three mineral absent from the binary diagram. Technically, the polymorphs of materials in high temperature are less dense than the low temperature.
However, the sillimanite (~ 3.2<ρ<~3.3 Mg.m-3) is denser compare to andalusite (~
3.1<ρ<~3.2 Mg.m-3). This condition due to the portion of Al cations change in the coordination number within the crystal structure. The coordination change is form the strange value of fivefold within andalusite to just fourfold within sillimanite. Kyanite having the highest density (~ 3.5<ρ<~3.5 Mg.m-3) compare to andalusite and sillimanite.
18 The phase diagram in Fig.2.5 shows the triple point of P-T which is located at approximately 3–6 kbar pressure and a temperature of approximately 400–650°C.
Kyanite forms in high pressure while sillimanite forms in high temperature structure.
Andalusite occurs at lower pressures and temperature. The three mineral will decompose to produce mullite and reject very fine highly reactive silica, when heated above approximately 1200°C (Shackelfard and Doremus, 2008).
Figure 2.5: Phase diagram for Kyanite-andalusite and andalusite-sillimanite (Shackelfard and Doremus, 2008).
19 2.5 Mining Technology of Andalusite
In South Africa the andalusite sand deposit are mined by open cast method, using face development and beach mining procedures. The basic in mining procedure is to remove the overburdens by using of bulldozer, loader and trucking operation. The thickness of overburden rang from a few meters up to 60 m, for example in northeastern
Transvaal. As long as the ore exposed rippers, scrapers, or face-shovels need to be apply for ore-loosening operation. The ore become harder at depth, so blasting indeed for the operation of loosening ore. The sorting to control the blasting is required for all the mining that control coarse crystal. The strike lengths of the deposit range from 2 km to 8 km, and the thickness of the ore up to 100 m. The andalusite ore is not consistent, varies from 8% to 20% which an average of 10% (Overbeek, 1989).
In Glomel, France, andalusite form in schist deposit which is deeply weathered and friable until 9.1 meters depth. The ore was drilled with a wagon drill and then using vertical blasting and further broken by hydraulic-percussion lump breaker. Ore was transported with a rubber-tired front-end loader with a 2.29 m to 2.74 m bucket (Sweet. et al., 2006). Next, ore was crushed by using jaw and gyratory crushing. In the grinding process semi-autogenous milling using steel balls had been applied. The andalusite crystals after the liberation are much finer than South Africa product. The procedure will seriously affect the viability if apply to South Africa, but most deposit are relative to simple and inexpensive mining and liberation procedure (Overbeek, 1989).
20 2.6 Application of Andalusite in Industry
Approximately 95% of andalusite of sillimanite group minerals are use as raw materials for the industrial of non-basic, high-alumina refractories approximately 95%
(O'Driscoll and Harries-Ress, 1993), another portion being use in ceramic, purposes, aggregate component in brick and other precast shaped products (Sweet. et al., 2006).
These mineral have the ability to form the refractory mullite phase which is provide high strength with resistance to physical and chemical corrosion at high temperature. The capacity to convert to mullite is about 85% and silica around 12% when the temperature heated from 1250 °C to 1500 °C (Sweet. et al., 2006).
Sillimanite minerals also importance iron and steel industries and more in the mullite refractories (Dickson, 1996). Mullite is a very necessary component of refractories that use in critical areas of furnaces like the inner lining of furnaces, high temperature container in the non-ferrous metallurgical and glass industries as well as in ceramic and cement kilns (RoskillInformationServicesLtd, 1990).
Compare to other aluminosilicate materials andalusite is great natural resources of mullite which is form at low temperature. The material had been use in many purposes in refractory due to the several advantages such as high creep resistance and very high stability because of the mullite transformation in firing create a pseudo single crystal structure. Each andalusite grain forms a single crystal of mullite with a capillary porosity that forms in the mullite matrix during the mullitization (Ildefonse et al., 1997).
It is use as raw material in glass (chutes, feeders, regenerators), chemical (fittings for
21 firing furnaces, drums), cement (rotary kilns), and aluminum (furnaces for firing anodes) industries and in ferrous metallurgy. Moreover, andalusite use varies in ferrous metallurgy such as blast furnace, air heaters, cast-iron production, mobile mixers, cast- iron transport ladles, intermediate ladles, and heating furnaces (Dubreuil et al., 1999).
Sillimanite and andalusite can be used in their raw stage due to the volume expansion only 4-7% during mullitisation. According to the energy that use for calcination, these two mineral is substantial cost saving compare to kyanite which is expends considerably during heating (Ihlen, 2000).
There are a good experience of using andalusite for lining transportable mixers obtained from European metallurgical plants such as Hoechat in Germany, British Steel
(Great Britain), and Sacilor (France). The lining serves for 800 to 1200 pouring with 2-3
(Maximum) intermediate repairs performed by guniting. For some French metallurgical imported andalusite from a refractory plant in Great Britain which is 59% Al2O3 with standard 70 to 100 pouring use in lining of hot-metal transfer ladles. Magnesite-chromite or magnesite-carbon had been use by The British Steel and Hoogovens (Netherlands) for lining the functional part of the slag line, and andalusite refractories for lining the walls and the connection zone of the bottom in steel-casting ladles, more importantly those with a capacity of over 150 tons. According to the data consumers service life amounts to 100 heats for the walls and 60 heats for the bottom, proved that the replacement of chamotte by andalusite make reinforced layers increases by a factor of 20 (Dubreuil et al., 1999).
22 2.6.1 World Production of Andalusite
Oxygen (O), Silica (Si) and Aluminum (Al) are the most abundance element in the earth‟s crust, so it is not surprise that sillimanite mineral exists in many deposit worldwide. Though, due to the qualities and grades of the deposit, some are not suitable for large scale commercial mining and beneficiation. Many are just small quarry operations and some are not economic enough to the operation (Sweet. et al., 2006).
There are only a few noticeable deposits worldwide.
Approximately 430 000 tpa of andalusite was produce by a few well know companies over the world show in (Table2.2). The main aluminosilicate mineral producer is South Africa which the produced 295 000 tons of andalusite in the year
2010. It was a mainly used as a feedstock for refractory and foundry products. The second producer is France gave the 80 000 tpa capacity, followed by China about 40 000 tpa. Peru and Spain new market support following the trend in 2012.
In South Africa expected to raise 32% andalusite production from 295 000 tpa in the years 2010 to 390 000 tpa in the next 3 years. Imerys subsidiary Damrec produces more than 70% of andalusite in the country reported a reserve 51 million tons of aluminosilicate (andalusite and sillimanite) ore. Beside the two giant company, the new comer company called Andalusite Resources Ltd. produce 70 000 tpa with a 60 years mine life, but the company expect to increase to minimum 80 years mine life.
23 Peru is the new comer who entered market almost two years ago (2007) since
Andalucita SA company start produces their product in August 2009. Imerys owns 5% of the same deposit (the deposit located near Paita in the north-west of the country). The andalusites that produce by Andalucita are technically 59% Al2O3 and 0.8% Fe2O3 with the production of 15 000 tpa and predict to increase to 55 000 tpa by mid-2012 (Feytis,
2011). Table 2.2 shows the major production of andalusite around the world.
Table 2.2 : Major Andalusite producer (Feytis, 2011).
Forecasted Country Company Capacity (tpa) Capacity
(tpa) South Samrec/Rhino 225 000 290 000 (2013) Africa (Imerys)
80 000-100 000 Andalusite 70 000 (end 2012) Resources Damrec ( NA France Imerys) 80 000
40 000 40 000 China Imerys Yingkou
Andalusite from 15 000 in Sept. 2010) NA Mineral
15 000 55 000 ( mid-2012) Peru Andalucita SA
Picobello Not started yet 65 000 ( mid-2012) Spain Andalucita SA Total 430 000 650 000
2.7 Geology of Terengganu
Andalusite mineral was discover in the years of 2010 which is occur as trace mineral with granite rock. Since then the andalusite mineral had been notice (Gasim et
24 al., 2010). State Mineral and Geoscience Department Director Zukeri Abdul Ghani provide some information related to andalusite in Terengganu. In July 2013, director said there are numerous researches still going on about andalusite in Terengganu.
Along the coastal side of Terengganu between 102°30ʹ00ʺ to 103°30ʹ00ʺ E and longitude 4°00ʹ00ʺ to 6°00ʹ00ʺ N has a distribution of rocks expose. Stratigraphically geology of Terengganu have been grouped as Carboniferous-Permian, meta-sedimentary rocks, Triassic igneous rocks, Jurassic-Creataceous continental rocks, and Quaternary deposit (Yin, 1985). Carboniferous older meta-sedimentary had been found in South
Eastern part of Terengganu, mainly schist, phyllite and slate surrounded by Early
Triassic granite and quaternary sediments (Bignell and Snelling, 1977).
The weathering activities in tropical region show intensive chemical and mechanical weathering because this area is a tropical zone. Due to the long exposure of the rock to the atmosphere with a different pressure and temperature make the rock breakdown by weathering and erosion process. The weathering agents that consider as the medium factors for generated depth to the weathering profile are rainwater, oxygen, carbon dioxide and plant decay acid. Temperature and soil moisture of the environment activated the weathering process. In Terengganu cover under the weathering grade III to
VI which is grade I is rock and grade VI is soil. In the area show that grade IV and V materials brown color underlie the grade VI materials and cover the forest floor. This may lead to the liberation of andalusite and expose.
Figure 2.6: shows the geological map Teregganu. Major rocks present in Teregganu area are marine and continental deposits which is phyllite, slate, shale, sandstone,
25 argillaceous rock are commonly carbonaceous, and also sandstone/metasandstone with subordinate siltstone, shale and minor conglomerate. Along the border of Southern-
Eastern, Eastern and Eastern-Northern made up of marine and continental deposits which are rich of clay, silt, sand, peat with minor gravel, sandstone and metasandstone.
10 0 10 3 10 0 10 3
5 5 3 3
5 5 0 0
4 4 3 3
4 4 0 0
10 0 10 3 10 0 10 3
Figure 2.6: Geological map of Terengganu area (Extracted from Geological of Penninsular Malaysia) (Hutchison and Tan, 2009).
26 2.7.1 Stratigraphy of South and Central Terengganu
Between the major river such as Sungai Kemaman, Sungai Dungun, Sungai
Terengganu and the coast developed beach ridges occurred the quaternary deposits.
Generally, the deposit found as fluvial deposits and as sediment that cemented in a marsh enviroment deposit along the coast and in structurally controlled depressions inland. Beach ridge mostly found along this coast and the wide is 4.5 km located north of Kuala Terengganu, Kerteh and south of Kemaman. These beach ridge is approximately 10 km inland Kemaman which beach sand range from 150 to 780 µm
(Bosch, 1988). Fluvial deposits existent strictly at the valleys and flood-plains of the major rivers and their tributaries. The morphology of this area are levees, meander cut- offs and abandoned channels. The lithology of the deposits range from poorly–sorted silty sand to sandy silt and the sand mostly are fine grained, however the coarse sand found farther inland. In Sungai Terengganu, Batu Rakit, Paka, Kerteh and 7 km west of
Tanjong Gelang also found the occurrence of Pleistocene terraces along the flood- plains
(Bosch, 1988). Behind the coastal sand ridges occur the swamps with a thin peat layer over marine clays. The swamps are underlain by marine sands or Pleistocene sediments.
2.7.2 Structure and Deformation in Terengganu
Several major north-striking faults found in Terengganu. One of them is about 60 km along the west side of the Besut valley, and another one cut across the north portion and 35 km farther southward along the Pertang valley called Lawit Granite (MacDonald,
1967).
27 In Figure 2.7 (a) the N-S faults occurs lineaments flanking granite batholiths.
The faults named after from west to east as Besut, Kampong Buloh, and the Ping-Teris
Fault Zone (Tjia, 1999). Faults length is 150 km which is cut through Permain to Upper
Triassic granites.
The Besut and Kampong fault zone have a strike N-S and dip direction steeply to the east. According to the Figure 2.10 (b) the southern ends of these faults change into
NNW-SSE tending lineaments which are cut along the Lawit and Kapal granite body, specifying the age during post-late Triassic. Ping-Teris faults strikes N-S cut
Carboniferous slate and phyllite giving rise to phyllonitic fault zones with contorted quartz veins (Tjia, 1999). Rocks exhibit through three phases deformation within this fault zones, and the drag folds and contorted quartz veins indicate dextral movement.
Mostly in the pre Jurassic peniod period, rocks have undergone multiple deformations, and the Eastern Belt is one of those. The entire Carbo-Premian strata in
Eastern Belt display the effect of multiple deformations. In Eastern Belt the palaeozoic strata have undergone minimum two generation of folding follow by brittle faulting
(Tijia, 1987). At Bukit Bucu in Terengganu the fossiliferous carboniferous strata have been deformed into a NNW pluging anticline which lack of cleavage (Idris and Zaki,
1986). The beds have strike direction to NNW-SSE and dip direction steeply to ENE.
(Abdullah, 2001) revealed that the strata in Rhu Rendang, Marang deformed into NNW plunging upright to overturn anticline, and continue to deformed into open folds then finally cut by later brittle strik-slip faults. The structure at Bukit Bucu, Marang and
Dungun exhibit at least three simple phases of deformation. The earliest deformation
28 move upward to NNW-SSE trending tight to overturn folds and continue to deformed to asymmetric NNW-SSE treding open folds and it associated with reverse faults.
2.7.3 Geology of Sungai Cerul Area
The geology in Sungai Cerul belongs to Kambing beds. The metasedimentary rocks consist of an older argillaceous sequence known as the Keiu Slates, and a younger arenceous sequence known as the Terapai Metasiltstone (Lee, 1990).
The Keliu Slates consist more than 2000 meter of hornfels, slate and phyllite interbedded occasionally with bands of schist, micaceous metasiltstone, quartzite and rare metaconglomerate. The age of Kelie Slate was Early Carboniferous due to the evidence of fossil coral Zaphrentis. The sediments were interpreted to have been deposited in a shallow marine environment.
The Terapai Metasiltstones consist of more than 2500 meter thick of fine grained quartzite and metasiltstone, with minor intercalations of argillite, slate and phyllite and the unmetamorphosed equivalents.
2.7.4 Geology of Kemasik
At Kuala Kemasik, Terengganu exposed the interbedded meta-agillite and meta- arenite show the abundant but selective development of andalusite. Andalusite is
29 generally rare at the base of the bed, grading upwards to abundant at the more shaly top.
This grading is used to indicated way up of the beds (Chakraborty and Metcalfe, 1983).
2.7.5 Geological Study of Andalusite
In the central belt of Peninsular Malaysia present the high grade of kyanite and sillimanite which is a Barrovian metamorphism type. Late intrusive contact metamorphosed the rocks is places giving rise to andalusite (MacDonald, 1967). In
Sungai Siyah and many localities near the contact of Taku Schists and granite had been recorded the present of muscovite-bitotite schist containing andalusite. Taku Schists and granite located near the north Kelantan. Andalusite forms from a result combination of thermal and regional metamorphism (MacDonald, 1967) found that andalusite also contain in the heavy mineral concentrate from stream flowing over or locality of the contact between granite and schists. However, (Hutchison, 1973) shows that the andalusite in the Taku Schists is original metamorphic, it is not contact metamorphic since the made use of mineral to deduce facies series.
30 A B
Kemasik
Sungai Cerul
Figure 2.7: (a) Major faults in Peninsular Malaysia. (b) Regional N-S faults of Terengganu, Peninsular Malaysia: Besut, Kampung Buluh belt and Ping-Teris. The base is from the "Mineral Distribution Map of Peninsular Malaysia" published by the Geological Survey of Malaysia (8th edition 1988; original scale 1:500,000).
31 2.8 Andalusite Processing
The typical standard beneficiation in South Africa divided into different procedure due to the crystal size of the andalusite. The ore behave similar to the standard procedure, which is variation according to the beneficiation problem by producer. Even it is not a good sign to satisfied the processing standard but the producer focus on improving the recovery, reduce costs and providing higher grade product (Overbeek,
1989). Figure 2.11 demonstrates the flowsheets for the operation of andalusite beneficiation.
Andalusite Resources company in South Africa exports 67 % of the production and 33% for local market (Louw, 2011). Below are the processing design of the company:
Phase 1: The Company use Liebher 946 excavator, four 30 tons of western Sart rigid dump truck, a Liebher loader, a Bell loader, a 30 tonnes Bell excavator, a Mitsubishi grader and 25 tones Bell ADT and a Bell bulldozer. Ore was crushed, washed and screened down to the size -5 mm, and smaller than 0.5 mm discarded as waste to the slime dam. In the present time (2011), 70% of raw materials go to slime and in 100 tons of raw material only 30 tons go to DMS which is product the 6 tons of final product.
Phase 2: Ferro silica was us as a media in dense media separation to separate the 30 tons output from the crusher. To adjust the density in DMS operation at the mine site, water had been used either adding or reducing and densitometer is in need to control the density.
32 Coarse crystal Fine crystal ore ore
Run of mine Run of mine ore ore Vibrating grizzly Vibrating feeder Feeder, 50mm with grizzly aperture
Jaw crusher Jaw crusher to 50mm
Vibrating screen Attrition scrubber 12mm aperture
Screening Gyratory or rolls Crusher to 12 mm
Coarse fines Attrition scrubber DMS Wet vibration screen
12mm and 1mm Sink Float
waste Dryer >12m <12mm <1mm
m > 1mm Waste Magnetic Separatio DMS n
Sink Float
Dryer
Screen
Magnetic separation
Figure 2.8 : Schematic Flowsheets for plant operation on coarse and fine crystal andalusite (Overbeek, 1989).
33 2.9 Microwave Treatment
2.9.1 Introduction
The microwave oven first developed in 1951 was produced by the Raytheon
Company of North America (Osepchuck, 1984). In early 1960‟s ovens available for domestic use and become a huge market. Not too long the industrial application started considered and used in rubber extrusion, plastic manufacture, and the treatment of foundry core ceramics. In mid-1970‟s the research on microwave application increased due to the insufficient energy costs of international oil and gas. In 1978 the first invention of exposed minerals to microwave radiation had been done by (Zavitsanos,
1978) which the application desulphurization of coal using microwave. (Chen et al.,
1984) open the research gate by renewed with the publication relating to relative transparency of mineral to microwave energy.
Several different application of microwave radiation has been suggested in mineral processing and extractive metallurgical. The basic principle of all the application of the ability of microwave depended on the phases within a mineral matrix.
Through the studies on microwave radiation response to the minerals (Walkiewicz,
1988) concluded that most of the silicates, carbonates and sulphates were transparent to the microwave radiation, however, most sulphides, arsenides, sulphosalts and sulphoarsenides heated strongly were emitting fumes and fusing.
34 (Walkiewicz, 1988) addressed more detailed about temperature measurement in microwave treated samples such as quantitative heating characteristics of various mineral and compounds. The selected materials were exposed to 1 kW, 2.45 GHz heater.
Table 2.4 shows the result of temperature and rates of heated determined. The metal sheathed thermo-couple had been use to overcome the temperature measurement problem. It is constant contact with sample and measurements on boiling water showed the system to be accurate to within 2%. The sample 25 g had been used for all tests, exclude the low density minerals used 18 ml volume. The result achieved not different form (Chen et al., 1984) which were certain groups of minerals could be identified as good heaters and other as poor heater. The importance observation for this study was the rapid heating of ore minerals within a non-absorbing matrix generated thermal stresses, this caused cracking which was both trasgranular and intergranular in nature. This work had been given to potential applications of microwave in mineral processing. Though, the application in industrial maybe limited due to the cost of equipment.
Table 2.3: Summary of mineral heating rate (Walkiewicz, 1988)
Mineral Chemical composition Max temp. achieved (°C) Time (min)
Chalcopyrite CuFeS2 920 1 Galena PbS 956 7
Magnetite Fe3O4 1258 2.75
Orthoclase KAlSiO3O8 67 6
Pyrite FeS2 1019 6.75
Quartz SiO2 79 7 Sphalerite ZnS 88 7
35 The microwave heating tests conducted by (Chunpeng et al., 1990) on some oxide, sulphides and carbonate minerals. Using 50g sample powder per batch, with an input microwave power of 500 W of 2450 MHz frequency and 4 min exposure time constant. Table 2.4 show the majority of oxide and sulphides minerals heated well.
Table 2.4: The Effect of microwave heating temperature of various minerals at 500 W, 2450 MHz (Chunpeng et al., 1990).
Minerals Chemical composition Time(min) Temperature(8°C) Jamesoite PbSbSZnS 2 >850 Titanomagnetite TiO2.yFe3O4 2 >1000 Galena PbS 4 >650 Chalcopyrite CuFeS2 4 >400 Pentlantite (FeNi)9-xS8 4 >440 Nickel (FeNi)1-xS 4 >800 pyrrhotite Cu-Co sulphides xCu2S.yCoS 4 >800 Sphalerite ZnS 4 >160 Molybdenite MoS2 4 >510 Stibnite Pb2S3 4 Room Temperature Pyrrhotite Fe1-xS 4 >380 Bornite Cu3FeS4 4 >700 Hematite Fe2O3 4 >980 Magnetite Fe3O4 4 >700 Limonite mFeO2.nH2O4 4 >130 Cassiterite SnO2 4 >900 Cobal hydrate CoOn2H2O 4 >800 Lead PbMoO4 4 >150 molybdenate Iron titanite FeTiO3 4 >1030 Rutile TiO2 4 Room Temperature Lead carbonate PbCO3 4 >180 Zinespar ZnCO3 4 >48 Siderite FeCO3 4 >160 Serpentine Mg(Si4O10)(HaO)3 4 >200 Melaconite (Cu2,Al3)H2- 4 >150 x(Si2O3)(H2O)4 Antimony oxide Sb2O3 4 >150
36 2.9.2 Basic Concept of Microwave
The electromagnetic energy in the microwave associated with electric and magnetic fields that can cause the materials dielectric and contain dipole when these materials absorb the microwave radiation. When the microwave applied to dielectric materials, dipoles aligns and flip around due to the field become alternating. Afterward, the internal energy loss to friction, then the materials becomes heat.
In nature ores contain various mineral which have very different mechanical and thermal properties. The stress of different magnitudes will create within the lattice as long as the ores subjected to the energy due to heating and cooling process. The different mineralogical species have the different thermal expansion coefficients. The stresses will localize fractions of an intergranular and transgranular nature but not necessarily to catastrophic failure. The comminution will reduce due to these fractures, and this fracture caused along the boundaries between different mineral according to different absorption behaviours and thermal expansion coefficients of the materials (Wang and
Forssberg, 2000). The factors that effects dielectric properties (ability of material to absorb or generate heat) of the materials are frequency of the applied field, the temperature and the physical properties of the material. The other factors that related to physical properties are chemical composition, the water content, the particle size and also the crystallography.
Microwaves do not heat metals because metals have high conductivity and it is a conductor‟s class. The conductors are often used as conduits waveguide in microwave.
37 The materials which transparent to microwave called insulators used to support material to be heated. Finally, the Dielectrics materials have excellent absorbers of microwave energy are easy to heat. Table 2.5 show the frequency allocation for ISMI application of microwave. Table 2.6 show the mineral transparent to microwave.
Table 2.5: Frequency allocation for ISMI applications (Haque, 1999).
Frequency MHz Frequency tolerance Area permitted 0.07 10 KHz Russia 13.56 0.05% world-wide 27.12 0.60% world-wide 40.68 0.05% world-wide 42, 49, 56, 61, 66 0.20% UK 84.168 0.005% UK 432.92 0.20% Austria, Netherlands, Portugal, Germany, Switzerland, Yugoslavia 896 10 MHz UK 915 13 MHz North and South America 2375 50 MHz Albania, Bulgaria, Hungary, Romania, Russia, Czechoslovakia 2450 50 MHz world-wide 3390 0.60% Netherlands 5800 75 MHz world-wide 6780 0.60% Netherlands 24,150 125 MHz world-wide 40,680 UK
38 Table 2.6: Minerals that is transparent to microwave irradiation at 2450 MHz, 150W, 5 min exposure time (Chunpeng et al., 1990).
Mineral class Minerals/compounds
Carbonates Aragonite, calcite, dolomite, siderite
Jarosite-type compounds Argentojarosite, synthetic natrojarosite ( zinc plant
residue, Kidd Creek Mines), synthetic plumbojarosite
(zinc plant residue,Cominco)
Silicates Almandine, allanite, anorthite, gadolinite,muscovite,
potassium feldspar, quartz, titanite, zircon
Sulfates Barite, gypsum
Others Fergusonite, monazite, sphalerite low-Fe , stibnite
2.9.3 Application of Microwave Assisted Liberation
Liberation using microwave had been studied and publishes by (Walkiewicz et al., 1993). This study focused on iron ore which applied the radiation 3kW, 2, 45 GHz and the temperature between 840 and 940°C. There are fractures between boundaries and through the gangue matrix was confirmed by SEM. Also the work index had been reduced about 10 to 24% according to the standard bond grindability tests (Walkiewicz,
1988). Treated sample with microwave provide a cleaner liberation of the valuable mineral particle that help to improve the concentrate grade and metal recovery after processing. Beside this there are more additional benefits such as less wear of the mill,
39 the mill liner and the milling medium, and also the amount of ores recycled will be reduced.
Another study on the effect of temperature and power level on bond work had been investigated (Walkiewicz et al., 1993). The temperature that use to heated taconite feed material was 12 and 16 kW. In all power levels confirmed that microwave energy can induce thermal stress cracking which is a good significant to improve the grindability. The material was heated to 880°C and to 197°C by microwave radiation to for the comparison. As a resulted the ores heated at lower temperature reduce more
Bond work index which is considerably improved the cost effectiveness.
An investigated more related to the possibility to increase the recovery of valuable mineral after microwave treatment (Kingman et al., 2000). Ores that had been used in this research were Massive Norwegian ilmenite ore, massive sulphides from
Portugal, highly refractory gold ore from Papua New Guinea and the carbonatite ore from South Africa (Kingman et al., 2000). The results in 2.6 kW microwave radiation treatment showed major effect both ilmenite and carbonatite ore, sulphides ore demonstrates the reductions in work index due to increase the expose time, and finally for gold ore revealed no effect in the work index. The research was concluded that the sample with a mixture of „good heaters‟ and „ medium heaters‟ in a lattice of „ poor heaters‟ with coarse grain size give the best reduction in work index after treatment. The ores that was contained high disseminated and fine grained minerals gave less effect.
Even though the technical work showed great benefits, but the economic were poor due to compensate for energy consumption not enough f or microwave preheating.
40 CHAPTER 3
MATERIALS AND METHODS
3.1 Introduction
The andalusite bearing rocks deposits were collected from two different locations in Terengganu. The first samples were obtained from Sungai Cerul (andalusite bearing rock and alluvial) whereas the second samples were collected at Kemasik (rock type).
These natural andalusite deposit samples belong to similar geological formation which is not much diverse in mineralogical, chemical and physical properties.
The assessment and experimental works were divided into three main parts that were samples characterization, grind ability for liberation study of andalusite minerals, and the effect of microwave treatment in the liberation processes. In the characterization part, the andalusite bearing rock was characterized in term of mineralogical and chemical study. The andalusite primary productions depend on grinding method.
Samples were crushed and bring to grind with three different rotations speed such as 10 rpm, 20 rpm and 30 rpm for 40 minutes. For the microwave treatment part, rock samples were divided into two parts. First sample was treated directly to microwave with three different temperatures such as high, medium and low heat. Second sample was soaked in water for 30 minute before treated with microwave at the same parameters with the first sample. The purpose of this chapter is to outline the sample preparation, experimental set up and equipment used during the research investigation. Figure 3.1 shows the
41 experimental procedure and analytical technique used to evaluate and process andalusite
minerals.
Field work (Site sampling)
Samples Sungai Cerul & Kemasik (Laboratory sampling)
Sample Andalusite primary Microwave preparation production (Sample treatment (Sample from Sungai Cerul) from Sungai Cerul)
Crushing Crushing Dry Sock in Grinding sample water(30min)
Grinding Mineral
characterization Treated by
(Sungai Cerul 10rpm/40min microwave
& Kemaman) 20rpm/40min High Medium Low 30rpm/40min heat heat heat Mineralogical Chemical study study
- Thin - XRF Grinding Section Sieving (20rpm) - XRD
- SEM/EDX
Assess the grade Andalusite Andalusite
of raw material production production
Figure 3.1: Flow sheet of experimental work
42 3.2 Raw Materials
Raw materials used throughout the work were andalusite samples that were collected from Kemasik in Teregganu whereas the second samples given by Mineral and
Geoscience Department (JMG) located in Sungai Cerul, Teregganu. Both andalusite bearing rock were in the form of hard rock.
100km
Figure 3.1: location of andalusite sample samples in Terengganu, Malaysia.
3.3 Ore Sampling
Throughout this work two types of sampling were applied which are site sampling and laboratory sampling.
43 3.3.1 Site Sampling
Site sampling was done at the study area from the large outcrop. The sample was selected randomly from the outcrop in different spots and mixed together to form the base for the final sample. The distance from one spot to the other spot was around 2 m interval. Approximately 3-4 kg of each samples were collected.
3.3.2 Laboratory Sampling
Laboratory sampling was divided into two parts which is coning and quatering, and Jones‟s Riffle sampler. Sampling had been done by coning and quatering before put into jaw crusher. Crushed sample was then split into sub sample by using Jones‟s Reffle sampler until appropriate amount of samples for mineral characterization.
3.4 Characterization of Raw Materials
3.4.1 Mineralogical Analysis
3.4.1 (a) Thin Section Preparation
Selected samples from Sungai Cerul and Kemasik were cut into slices of 2 cm thick and 4 cm length by using rock cutting-machine (Buhler Petro-cut). The slices were grinded with sand paper of various grits (400, 600, and 800 gride) and then polished with silicone carbide powder until achieve a smooth surface on one side of the slice.
44 Doing this provided a best surface to rock slice in order to make it easy to lap on the microscope glass slice.
The microscope glasses slices were frosted to have a rough surface in one side.
Rock slice were boned to the clear slice of the glass using Balsam Canada (solid form).
The microscope glass had been placed in the hot plate to make the glue melt. The rock slice was placed on the glass when the glue started to melt. In order to produce good thin sections avoid any bubble from trapped on the surface of the sample. Once rock slice and glass boned together, leave it a day to make it stick perfectly.
Harden sample was then trim by using trimming machine (Buhler Petro-thin) until appropriate thickness was obtained. After you achieved a good thickness, one a gain polished the other site of rock slice with silicon carbide powder to get rid of the excess or remain thickness and also to smooth the surface of the sample. The contents of the rock can be seen clearly by this step. This procedure continues until achieve 30 µm thicknesses, and ready for transmitted light microscopy. The thin section samples were then observed for mineral identification by sued Olympus BX51 Polarizing microscope.
45 a b
c d
Figure 3.3: Equipment used for thin Section. (a) cutting machine (Buhler Petro-cut) (b) Trimming machine (Buhler Petro-thin). (c) Grinding machine. (d) thin section sample.
3.4.1 (b) XRD Analysis
X-ray powder diffraction (XRD) is an analytical technique used for phase identification of a crystalline material and provides information on unit cell dimension.
In this study X-ray diffraction analysis was applied to identify presented in the samples.
The basic concept of XRD was Bragg‟s law.
nλ= 2dsinϴ………Equation 3.1
Where:
n= order of radiation λ= X-ray wavelength d= crystal lattice spacing ϴ= incident angle
46 Approximately 25 g of the samples were ground to -75µm prior analyzed by
XRD. The measurements were carry out using Bruker D-8 filtered with Cu-Kα (λ=1.542) radiation operated at a beam voltage and current of 40 kV and 2 mA, respectively. The
XRD pattern was recorded in the range of 2ϴ= 10°-80° using a step size of 0.034°.
Results obtained from the analyses were then analyzed by X‟pert High Score software for qualitative and quantitative mineral information.
3.4.1 (c) Scanning Electronic Microscopy (SEM) and EDX
Technically SEM was used to capture the surface of the sample (morphology) with the action of electron beam scanning across the surface of a specimen. All the SEM result obtained in this study were taken with the SEM model LEO Supra 35VP operating in the secondary electronic mode at an acceleration voltage of 5-15 kV. The specimen prepared by cut a representative sample into an appropriate shape and then makes a mold by using resin and glue with a ratio 1:2. Furthermore, the sample was grind with sand paper to get a smooth surface and polished with diamond polishing to obtain the high reflectivity, and to prevent any scratching on the surface. To avoid scanning faults caused by electrostatic charge at the surface, therefore the specimens need to be coated.
In this study the sample was coated with an ultrathin coating which is gold.
Energy dispersive X-ray Spectroscopy (EDX) was used for identification and qualification of the element. The EDX is attached to an SEM which provides an incident electron for secondary X-ray emission.
47 3.4.2 Chemical Analysis
3.4.2 (a) X-ray Fluorescence Spectrometry (XRF)
X-ray fluorescence is a nondestructive method for elemental analysis of solids and liquids. In a particular application demand the limitation of impurities and the detailed chemical analysis was carried out by using XRF.
A representative sample was ground to less than 200 μm and further ground in agate mortar to less than 75 μm before analysed. The chemical composition analysis of the andalusite sample was carried out by XRF, model Rigaku RIX 3000.
3.4.2 (b) Loss on Ignition (L.O.I) Determination
L.O.I is one of the method used to evaluation the amount of organic matter and carbonate mineral content (indirectly of organic and inorganic carbon) in sediments
(Santisteban et al., 2004). With easy and practicable make this method commonly use.
To calculate the loss on ignition, the equation was applied:
LOI(%)= [ ]× 100…………equation 3.2
Where: M1: Mass in grams before ignite M2: Mass in grams after ignite
48 The powder of representative sample had been dry for 100°C for 24 hours for precipitated the water. A 3 g sample placed in ceramic crucible which was a good requirement for the test. The laboratory furnace temperature increased 5°C for 3 hours until reach 950°C. The sample ignited for 2 hours with the socking time 950 °C. After the socking time 3 hours, furnace and sample went down to room temperature. So the loss weight was calculated and recorded as a percentage of the original sample weight.
3.5 Andalusite Production
3.5.1 Crushing
The andalusite crystal was obtained by just crush the raw material using jaw crusher since phyllite is not a very hard material (in this case phyllite deeply weathered). The initial size of andalusite bearing rock approximately 5-40 cm which was reduce size by sued two jaws crusher (model SWING Jaw-SEVDALA and laboratory crusher). Figure
3.6. After the crushing procedure, some of the andalusite particle had been liberated from matrix. In this case sieving analysis had been practice to obtain the primary product of andalusite. The products available in different sizes due to the sieving procedure. In this work Vibrator Sieve Shaker RETSCH A9200 was applied. Sample was poured onto the coarsest sieve at the top and sieve was carried out for 5 minutes and amplitude 1.5.
Individual size fraction retained on the sieves was weight and keep as a production and waste (matrix). The bigger size that still not liberated was then grinding by suing rode mill in order to achieve the secondary product.
49
Figure 3.4: Laboratory Jaw crusher
3.5.2 Grinding Process
Concerning to achieve the optimum result for in grinding process, three different experimental set up had been applied. Samples were weight and divided into three fractions for grinding process.
650 g samples put in rod mill with the rotation speed 10 rpm for 40 min.
650 g samples put in the rod mill with rotation speed 20 rpm for 40 min.
650 g samples put in the rod mill with rotation speed 30 rpm for 40 min.
After grinding the sample was sieve in a series of sieves which arrange accordingly.
The horizontal stainless steel mill with the diameter 25 mm and 30 mm length was used in the grinding experiment. The other parameter setting are rod, rod had been used in different diameter and sizes ( 2.5 mm, 2 mm, 1.2 mm and 0.5 mm), and the ratio 1:10
50 between rod and samples. The evaluation of this products was achieve by using sieving analysis in different sizes such as 5 mm, 3 mm, 1 mm, 0.6 mm and 60 µm.
a b
Figure 3.5: (a) Pascal rod mill, (b) rods in different size.
3.6. Microwave Treatment
The influence of microwave treatment for assisted grinding had been study and publishes by Walkiewicz since 1991 (Walkiewicz et al., 1993). The microwave treatment had been useful to reduce bone work index such as grinding and processing.
In the case of finding optimum result for microwave treatment, this method was divided into two parts which is using dry sample and wet sample. The sample for this experiment was cut into dimension 5-7 mm×4 mm ×4 mm. The representative samples
(both dry and wet) divided into three fractions. The microwave used in this research work is home microwave model Panasonic Circa 1993 which is available in the laboratory.
51 3.6.1 Dry Sample Experiments
Dry sample was cut into the dimension as mention earlier, and treated in microwave in three different temperatures due to home microwave design which is:
- High heat
- Medium heat
- Low heat
3.6.2 Wet Sample Experiments
The samples in the same dimension was then sock in water for 30 minute, and treated by microwave in three different temperature due to home microwave design which is:
- High heat
- Medium heat
- Low heat
In Figure 3.7(a) showed dry sample before treated by microwave, (b) wet sample before treated by microwave, (c) place the sample in the microwave (d) home microwave used in this research work. The microwave used in this research work is home microwave model Panasonic Circa 1993 which is available in the laboratory.
52
a b
Figure 3.6: Treatment process. (a) dry sample, (b) wet sample, ( c) sample placed in microwave, (d) Home microwave.
3.6.3 Andalusite Production from Microwave Treatment
The experiment on grinding methods and Microwave treatment method provide a suitable conclusion for the second production of andalusite. The samples were sock in water for 30 minute and treated in microwave in low heated for 15 minute. Next, bring the treated sample for grinding in rod mill for 15 minute with a rotation speed 20 rpm.
53 CHAPTER 4
RESULTS AND DISCUSSIONS
4.1 Study Location in Malaysia
Samples of andalusite bearing rock used in this study located in Terengganu,
Malaysia. The first sample had been taken from Sungai Cerul, and second sample from
Kemasik. The Sungai Cerul samples were in the form of hard rock, and slightly weathered. The Kemasik samples were hosted by phyllite and metasedimentary rock.
The rocks appeared to be high weathered. Table 1-3 show the summary samples used for the research work.
Table 4.1: Characterization Study
Characterization Study Kemasik Sungai Cerul Sample Sample K1 S1 Thin Section K2 S2 Mineralogical K3 S3 study SEM/EDX K4 S4 K5 S5 XRD K6 S6 Chemical study XRF K7 S7
54 Table 4.2: Grinding- Sungai Cerul Sample
Sample Rotation Speed Weight
SC1 10 650g
SC2 20 650g
SC3 30 650g
Table 4.3: Microwave Treatment with Home Microwave
Temperature Dry Sample Wet Sample
High SM1 SM4
Medium SM2 SM5
Low SM3 SM6
4.2 Physical Appearance
The first andalusite bearing rock sample located at Sungai Cerul was given by
Department of Minerals and Geo-sciences Malaysia (JMG). Figure 4.1 showed the representative samples of andalusite bearing rock from Sungai Cerul. The andalusite crystal mainly hosted phyllite and metasedimentary rocks. The deposit is basically consisting of a micaceous clay matrix in which the andalusite crystals occurs as phenocryst show in Figure 4.1. It can be seen that the average of andalusite crystal were up to 2-5 cm in length and 0.3-1 cm in diameter. The associated trace minerals are quartz, biotite, muscovite and magnetite. Figure 4.1 (a) shows the host rock phyllite are dark gray, fine grain and slightly weathered. The andalusite content in the phyllite is not
55 consistent, it is vary from 10% to 20%. (b) Rocks consist of highly weathered and fine grain phyllite, with the present of mica. The sample is softer than the samples in Figure
4.1 (a).
a Andalusite crystal
b Andalusite crystal
Figure 4.1: Selected andalusite bearing rock samples from Sungai Cerul. (a) Large crystal of andalusite bearing rock presented in slightly weathered rock. (b) Mica can easily be seen in highly weathered rock.
56 The second sample was taken from rock outcrop in Kemasik deposit
Terengganu. The outcrop located in Kemasik beach. Site sampling method had been applied to obtain a suitable amount of samples for laboratory work. In field area of
Kemasik, metapelitic rocks are the most abundant rock type, and are interlayer with calcsilicate rock (sandstone, metasandstone and quartz). Metapelitic rocks occur as phyllite, mica schist. Figure 4.2 outcrop in the study area. Figure 4.3 shows the andalusite bearing rock sample from Kemasik.
Figure 4.2: Outcrop of andalusite bearing rock in Kemasik.
57 Quartz vein
Phyllite
4cm
Figure 4.3: The andalusite deposit at Kemasik area. Various quartz veins presented in the rock from 2 cm to 5 cm width. Rocks are highly weathering.
The photograph detail of the selected sample from Kemasik area shows in Figure
4.4 below. It can be seen that host rock are mainly interbeded of phyllite, sandstone, metasandstone and quartz. From the observation of hand sample, it is hardly to see andalusite particle by naked eyes.
58
a b
c d
Figure 4.4: Selected rock specimens from Kemasik. (a) Sandstone (b) &(c) Meta sandstone with numerous micaceous muscovite which strongly altered (d) Phyllite, made up mostly of very fine grain mica which is muscovite.
59 4.3 Characterization Raw Material
4.3.1 Mineralogical and Petrography Analysis
4.3.1 (a) Ore Microscopy
Figure 4.5 shows the andalusite samples under optical microscopy of andalusite bearing rock from Sungai Cerul. Most of andalusite crystal is phenocrysts in a fine groundmass embedded of phyllite. The andalusite crystal is dull white which is 3 mm to
5 mm in length. In the center of the crystal there is a rectangular area full of inclusion caused by carbon or clay and radiating toward the corners of the crystal. This variety of andalusite known as chiastolite because of the cruciform pattern by the inclusion.
Chl An
1mm
Figure 4.5: The crystal of andalusite under optical microscopy with the magnification X70. An: Andalusite, Chl: chiastolite.
60 Figure 4.6 shows the andalusite bearing rock sample from Kemasik area. Even though, aluminum silica presented in the sample was significantly, but there are no particular shapes of andalusite crystal. Due to the high alteration, andalusite mineral experience chemical change which made the crystal deform.
Andalusite Crystal
Figure 4.6: The irregular of andalusite crystal under optical microscopy with the magnification X70.
4.3.1 (b) Thin Section Results
Sungai Cerul Sample:
Photomicrographs of andalusite bearing rock studied by using polarized transmitted light microscope are illustrated in Figure 4.7. Fig.4.7 (a) thin section under plane polarized
61 light indicated that the rock made-up of fine grained of foliated muscovite, sericite and biotite which are phyllite. It can also be seen that andalusite crystal is phenocrysts in a fine groundmass. This mineral is a polyphenic of silicates of aluminum indicative of conditions of formation of the rock at low pressure. (b) Shows the detailed of andalusite crystal and chiastolite. This variety of andalusite knows as chiastolite because of the cruciform pattern by the inclusion cause by organic matter most probably are clay or carbonaceous.
a
1 mm b
Andalusi Chiastolite te
1 mm
Figure 4.7: Photomicrographs illustrating andalusite in thin section: (a) strongly foliated phyllite with numerous muscovite, sericite and biotite (X20), (b) mineral andalusite embedded in phyllite (X50).
62 Kemasik Samples:
Figure 4.8 demonstrated the thin section sample of andalusite under polarized transmitted light microscopy with cross polarized light. (a) Fine grain phyllite which is the foliation made of muscovite, sericite and biotite. Muscovite appeared in pink color and fine grained, biotite appear in dark green and fine grained groundmass. The darker in line is iron oxide. Iron Oxide generally appeared dark in colour under thin section.
The present of iron oxide also confirm by XRF and SEM/EDX. (b) The andalusite under thin section andalusite shows a light purple pleochroism and fairly diagnostic. The natural crystal is scattered unevenly in characteristic, with various andalusite relief. (c)
The andalusite is colorless under plain polarized light.
a
b
Figure 4.8: Photomicrographs illustrating andalusite under thin section: (a) XPL(X20) uneven distribution andalusite (b)XPL (X100), (c)PPL(X100).
63 c
Figure 4.8: Photomicrographs illustrating andalusite under thin section: (a) XPL(X20) uneven distribution andalusite (b)XPL (X100), (c)PPL(X100). (continue)
4.3.1 (c) X-Ray Diffraction Result
The result XRD‟s patterns of andalusite sample from the study area were shown in Figure 4.9 and Figure 4.10. It can be seen that the quantitative analysis by X‟pert high score indicated that the sample rich in quartz and andalusite as the dominant mineral, in addition to a variety of minor and trace phases such as magnetite, muscovite and kaolinite (Figure 4.9). Figure 4.10 shows the XRD result that quartz is a main mineral and follow by andalusite and the minor phase of muscovite and kyanite.
64 35000
Q A: andalusite Mu: muscovite 30000 M: magnetite K: kaolinite Q: quartz 25000
20000
15000
Q
Intensity (arbitray unit) (arbitray Intensity 10000 K Mu K K Q A Mu M K K K Mu A Q Mu Mu 5000 Mu Mu AK MuM AM A A Q M A KAQ K k Q Mu A A
0 0 20 40 60 80 100 2 Theta Figure 4.9: Representative XRD diffractogram of representative sample from Sungai Cerul.
30000
A: andalusite
Q Mu: muscovite 25000 Q: Quartz K: kyanite
20000
15000
10000
Intensity (arbitrary unit) (arbitrary Intensity
K Q 5000 A A K Mu K MuQ Q Q K Mu Mu KA A A Q Mu Mu K Mu A K AMu A Mu A Mu 0 0 20 40 60 80 100 2 Theta Figure 4.10: Representative XRD diffractogram of representative sample from Kemasik area.
65 4.3.1 (d) Scanning Electron Microscopy Results
SEM-EDX observations of sample from Sungai Cerul revealed that the main minerals are andalusite, quartz and the trace mineral such as corundum, iron oxide, rutile and monazite. Figure 4.11 shows iron oxide with the particle size of less than 200 μm presented in the sample. Rutile often found occurred as disseminated mineral within a size larger than 220 μm and appeared flaky in shape measured in different size dimension about 50 μm. Figure 4.12 indicated traces of rare earth bearing minerals mainly monazite presented within a size range of 10-100 μm.
a
An A Crd
Mz
B An
Point A Point B
Figure 4.11: SEM-EDX analysis of andalusite with the presence of associated mineral. (An: andalusite, Crd: corundum, Mz: monazite).
66 b
C Ru
D
Crd Fe
E
An
Point Point c D
Point D
Figure 4.12: SEM-EDX analysis of andalusite with the presence of associated mineral. (An: andalusite, Crd: corundum, Ru: rutile, Mz: monazite).
67 The SEM-EDX represented the result of andalusite bearing rock sample from Kemasik.
It can be seen that andalusite and quartz are the main mineral and followed with trace minerals such as rutile, monazite and halite. The size of monazite presented in the sample range from 4 µm to 25 µm. Figure 4.13 show the unspecific shape of monazite with the size approximately 45 µm whereas rutile presented in the sample with size range from 10 µm to 25 µm. Since the originate of the sample taken from Kemasik area along the beach, the present of halite is inescapable. Halite disseminate all over the sample within the size range from 0.5 µm to 5 µm.
D Ru
B Ru Mo
A C An
Ha
Point A Point B
Figure 4.13: SEM-EDX analysis of andalusite with the presence of associated mineral. (An: andalusite, Ru: rutile, Mz: monazite, Ha: halite, Qu: quartz).
68 Point c Point D
Figure 4.13: SEM-EDX analysis of andalusite with the presence of associated mineral. (An: andalusite, Ru: rutile, Mz: monazite, Ha: halite, Qu: quartz). (continue)
4.3.2 Chemical Characterization
4.3.2 (a) XRF Result
The chemical analyses of the two andalusite bearing rock samples from the study area were showed in Table 4.4-4.6. Table 4.4 shows that andalusite bearing rock from
Sungai Cerul contains 30.93% of Al2O3, 55.07% SiO2, 5.66% K2O and 5.99% Fe2O3.
Table 4.5 shows the result of chemical composition of andalusite crystal itself. It shows that andalusite crystal contained 46.14% of Al2O3, 46.47% SiO2, 4.05% K2O and 2.26%
Fe2O3. Table 4.6 shows the chemical composition of andalusite bearing rock from
Kemasik area with the grade of 25.77% of Al2O3, 58.29% SiO2, 4.28% K2O and 4.44%
Fe2O3.
The microscopy study on the Kemasik sample indicated that the andalusite particle is hardly to be observed. It can also be seen that the purity of the andalusite is about 40.93% Al2SiO5. This condition demand special beneficiation to improve the grade of Al2O3. Based on the result, the beneficiation of andalusite from this deposit in
69 considered difficult with the current technology when compared with the economic value of its mineral. The purity of andalusite baring rock from Sungai Cerul is approximately 49% Al2SiO5 whereas the Purity of andalusite crystal is about 73.28%
Al2SiO5.
Table 4.4: Chemical composition of andalusite bearing rock from Sungai Cerul.
Chemical Composition Wt. (%)
SiO2 55.07
Al2O3 30.93
K2O 5.63
Fe2O3 5.99
Na2O 0.31 CaO 0.12 MgO 0.31
TiO2 0.7 BaO 0.08
Rb2O 0.05
Cr2O3 0.08
P2O5 0.04
Table 4.5: Chemical composition of andalusite crystal from Sungai Cerul.
Chemical Composition Wt. (%)
SiO2 46.47
Al2O3 46.14
K2O 4.05
Fe2O3 2.26
Na2O 0.29 CaO 0.21 MgO 0.18
TiO2 0.16 BaO 0.06
Rb2O 0.03
Cr2O3 0.03
P2O5 0.03 SrO 0.02
70 Table 4.6: Chemical composition of andalusite bearing rock samples from Kemasik area
Chemical A1 A2 A3 A4 A5 A6 Average composition (Wt.%) (Wt.%) (Wt.%) (Wt.%) (Wt.%) (Wt.%) (Wt.%) SiO2 46.64 64.44 55.76 57.96 62.21 58.29 57.55 Al2O3 34.54 18.89 26.91 28.85 24.7 25.77 26.61 K2O 5.57 2.78 4.6 5.35 4.43 4.28 4.50 Fe2O3 3.95 8.24 4.74 0.92 1.79 4.44 4.02 Na2O 0.81 0.42 0.62 0.33 0.3 0.48 0.49 CaO 0.3 0.03 0.11 0.01 0.06 0.09 0.10 MgO 0.47 0.27 0.46 0.41 0.83 0.45 0.48 TiO2 0.92 0.44 0.57 0.59 0.57 0.6 0.62 BaO 0.15 - 0.08 0.13 0.1 0.1 0.09 Rb2O 0.08 0.02 0.05 0.58 0.05 0.13 0.15 Cr2O3 0.02 0.02 0.02 0.02 0.16 0.04 0.05 P2O5 0.02 0.02 0.03 0.01 0.01 0.02 0.11 SrO 0.04 0.01 - 0.01 0.01 0.02 0.02 SO3 0.11 0.12 0.13 0.03 0.1 0.1 0.08 Cl 0.64 0.35 0.46 0.11 0.13 0.34 0.28
4.3.2 (b) Loss on Ignition (L.O.I)
The average result of L.O.I of andalusite bearing rock sample from Sungai Cerul was 0.64 whereas the average L.O.I of samples from Kemasik was 0.19. The higher
L.O.I of the samples from Sungai Cerul was due to the present of clay or carbonaceous matter.
4.4 Liberation and Separation of Andalusite
The first stage of liberation was obtained by crushing and sieving raw material.
Based on the mineralogical studied, it can be seen that andalusite crystals or particles were disseminated in andalusite bearing rock or cemented in phyllite rock. In order to
71 improve the grade of andalusite, the crystals need to be liberated. Figure 4.14 shows the andalusite bearing rock had been crushed with jaw crusher to break the rock and liberated the crystal.
1cm
Figure 4.14: Sample after crushed by Jaw crusher.
Phyllite can easily be crushed by jaw crusher due to the different in density. Density of phyllite is 2.7-2.9 g/cm3 and andalusite is 3.13-3.21 g/cm3. Comparatively andalusite crystal or particle is harder than the rock matrix. Therefore, liberation of the crystals from the rock can be done by comminution processes (crushing and grinding). In this work jaw crusher was used to liberated andalusite crystal from rock matrix.
Andalusite crystal can be separated by sieving the jaw crusher produced. This shows clearly that the particle smaller than 2.8 mm contain mainly rock matrix whereas particle bigger than 2.8 mm contain mainly andalusite crystal as shown in Figure 4.15 (a) and
(b). However, particles bigger than 8 mm were observed presented as interlocked
72 particle and need to be recycled until the appropriate size was obtained. In this case coarse particle (> 8 mm) were ground using rod mill at different rotation speed.
a
b
Figure 4.15: Andalusite crystal after crushing and sieving procedure. (a) andalusite crystal passing the sieve 6.33 mm, (b) andalusite crystal passing the sieve 2.8 mm.
73 4.4.1 Primary Liberation Grade
After through the crushing and sieving the grade of andalusite had been improved from
25.73% Al2O3 to 33.97 % Al2O3. Tables 4.7-4.8 show the improvement of andalusite by chemical analysis.
Table 4.7: Chemical analysis of andalusite grade before crushing and sieving
Chemical Composition Wt (%)
SiO2 60.47
Al2O3 25.73
K2O 3.84
Fe2O3 8.37
Na2O 0.11 CaO 0.27 MgO 0.2
TiO2 0.64
Table 4.8: Chemical analysis of andalusite grade after crushing and sieving
Chemical Composition Wt (%)
SiO2 56.34
Al2O3 33.97
K2O 3.68
Fe2O3 4.86
Na2O 0.1 CaO 0.21 MgO 0.16
TiO2 0.37
74 4.5 Effect of Rotational Speed of Rod Mill
The non-liberated particle from crushing, were further ground by a rod mill at three different rotation speed.
4.5.1 Rotational Speed at 10 rpm/40 min
Products retained in the sieve were than weight. The weight is 380 g, 150 g, 70 g and 50 g for +8 mm, -8 mm to +6.33 mm, -6.33 mm to +2.8 mm and -2.8 mm to +600
µm respectively. The result showed that the particle retained in 6.33 mm and 2.8 mm was the andalusite crystal, and – 600 µm is a waste and more than 8 mm send for further grinding.
70
60
50 40
30 10rpm10 rpm
20 10
% Passing Percent Cumulative 2.8mm 6.33mm 0 0 2 4 6 8 10 Sieve Size, mm
Figure 4.16: Particle size distribution of andalusite bearing rock after grinding
75 4.5.2 Rotational Speed at 20 rpm/40 min
Approximately 650 g of andalusite bearing mineral was grind for 40 min in a mill at rotation speed 20 rpm. After sieving the material had been weight which is 260 g,
170 g, 130 g, and 90 g for +8 mm, -8 mm to +6.33 mm, -6.33 mm to +2.8 mm and -2.8 mm to 600 µm respectively. Same thing as the first test, the material was liberated in the size range +2.8 mm to +6.33 mm, – 600 µm is a waste and more than 8 mm send for further grinding. With 20 rpm rotation speed, the result has been improved, by receive more matrixes.
45 40 35
30 25
20 20rpm20 rpm
15 10 5
% Cumulative Percent Passing Passing Percent Cumulative 2.8 mm 6.33 mm 0 0 2 4 6 8 10
Sieve Size, mm
Figure 4.17: Particle size distribution of andalusite bearing rock after grinding
4.5.3 Rotational Speed at 30 rpm/40 min
Approximately 650 g of andalusite bearing mineral was grind for 40 min in a mill at rotation speed 30 rpm. After sieving the material had been weight which is
76 299.35 g, 160.5 g, 190 g for 8 mm, 2.8 mm to -6.33 mm, and -600 µm respectively. The material was liberated in the size range +2.8 mm to -6.66 mm, – 600 µm is a waste and more than 8 mm send for further grinding. Within the 30 rpm rotation speed, the materials tend to be over grinding. Some fractions of the andalusite crystal over grind and go to waste.
70
60
50
40 30rpm30 rpm 30
20
10 Cumulative Percent Passing % Passing Percent Cumulative
0 2.8 mm 6.33 mm 0 2 4 6 8 10
Sieve size, mm
Figure 4.18: Particle size distribution of andalusite bearing rock after grinding
According to the observation of the grinding procedure above, the ideal for grinding andalusite bearing mineral was more efficiency in a rotation speed 20 rpm/40 min. Basically the andalusite crystal in the rock sample approximately 2 cm to 5 cm in length. However, in a rotational speed 10rpm/40min provided less crystal between the sieve of 6.33 mm and 2.8 mm, and rock barely break from the crystal. In addition, in a rotational speed 30 rpm/4 min tend to over grinding due to the result obtained more crystal at sieve 2.8 mm which mean that the course crystal hand been broken. Figure
4.19 shows the graph of cumulative percentage passing and the sieve size in three
77 rotation speeds. Based on the graph can bring to a conclude that the higher rotation speed the higher the higher percentage of fine particle remove to the waste.
70
60
50
40 10rpm10 rpm
20rpm10 rpm 30 30rpm10 rpm 20
10
% Passing Percent Cumulative 2.8 mm 6.33 mm 0 0 2 4 6 8 10
Sieve size, mm Figure 4.19: Particle size distribution of andalusite bearing rock after grinding with difference rotation speed.
4.6 Effect of Microwave Treatment
Figure 4.20 shows the crystal of andalusite cemented in phyllite rock. Based on the figure the interface between particle and matrix can be seen clearly.
78
Figure 4.20: Optical microscopy of andalusite crystal in their matrix before treatment by microwave (X70).
4.6.1 Dry Sample
4.6.1 (a) Dry Sample Heated in High Temperature
Figure 4.21 shows the sample of andalusite bearing rock before treated with high temperature in microwave. It can be seen that andalusite crystal approximately 0.5 cm to
1cm length and 0.2 cm to 3 cm width were cemented in the rock.
Central cross
pattern
Andalusite single crystals Matrix
Figure 4.21: Sample before treat by Microwave
79 The sample was put into microwave which was set at high temperature and break the sample after 38 sec after the switch was on. Broken sample were collected and observed the possibility of liberation of andalusite crystal from the rock at high temperature as shown in Figure 4.22 (a).
The result demonstrated that the sample started to burst and broke into small pieces along matrix boundaries not at the interface between andalusite and matrix. This might be due to the density of matrix is lower than andalusite particle. Figure 4.22(c) show the photomicrograph there are a microwcrack in the matrix area. However, the interface along the boundary between particle and matrix was not showing any crack Figure
4.22(b).
a
Breaking Zone
b c Andalusite grain
Matrix Microcracks
Andalusite grain Figure 4.22: The andalusite sample after treated in high heat by microwave. (a) Sample burst into small pieces. (b) The boundary of andalusite and matrix (X50). (c) Microwcrack along the matrix area (X50).
80 4.6.1(b) Dry sample Heated in Medium Temperature
The photograph and the micrograph of dry sample before treated in medium heat by microwave is show in Figure 4.23.
c
Andalusite crystal
Figure 4.23: Sample before treated by Microwave.
Sample of andalusite bearing rock was burst after 44 sec introduced to microwave at medium heat. It can be seen that the sample broke into pieces along the matrix and the same thing as high heat treatment there are no breakage along the interface between crystal and matrix as shown in Figure 4.24 (a) and (b).
a b Andalusite grain Matrix
Breaking boundary
Figure 4.24: The andalusite sample after treated in medium heat by microwave. (a) Sample broke along the interface of crystal and matrix. (b) Andalusite crystal under transmit light microscopy (X50).
81 4.6.1 (c) Dry sample Heated in Low Temperature
The photograph and the micrograph of dry sample before treated in low heat by
microwave showed in Fig.4.25.
Andalusite crystal
Figure 4.25: Sample before treated by microwave.
Figure 4.26 shows the initial sample of andalusite bearing rock which was introduce to microwave at low heat. This test took 5 minutes and 17 seconds to burst the sample into pieces. This indicated that the sample broke along the matrix and interface between andalusites crystal and matrix. Eventhough, the time break the rock sample a bit longer but a significant number of breakage at the interface can be seen clearly as shown in Figure 4.26(a), (b) and (c).
82 a b Breaking Crack boundary
Crack
Crack
c
crack Crack
Figure 4.26: Sample condition after treated by microwave in low heat. (a) Optical microscopy of breaking sample. (b) & (c) The fracture along the interface of andalusite crystal and matrix (X30).
4.6.2 Wet Sample Soak for 30min in Water
4.6.2(a) Wet Sample Treated in High Temperature
The photograph and the micrograph of sample which is sock in water for 30 minute before treated my microwave show in Figure 4.27.
83 a
Andalusite crystal
Figure 4.27: Wet sample before treat by Microwave
Figure 4.28 shows the sample that already sock in water and had been treated with high temperature by microwave. After 16 s in the microwave the sample started to burst and had broken along the interface of andalusite grain and matrix, also in the matrix area. In the same temperature as dry sample but wet sample start to break faster because of the water absorption make the boundary between particle and matrix weak.
Fig. 4.28 (a) Intergranular fracture was present in the ore Fig. 4.28 (b). Even there are fractures between particle and matrix, but those fracture occur only some part of particle surface in the ore. Fig.4.28 (c) demonstrated the uncrack surface of the crystal and matrix.
84 a
Breaking boundary
b c Andalusite crystal
Andalusite Matrix grain
Andalusite crystal Matrix Microwcrack
Figure 4.28: The andalusite sample after treated in high heat by microwave. (a) Showed the breaking along the boundary of crystal and surface. (b) The microcrack in the rock. (c) Unbreak surface of the rock.
4.6.2 (b) Wet Sample Treated in Medium Temperature
The photograph and the micrograph of sample which is sock in water for 30 minute before treated my microwave show in Figure 4.29.
a Andalusite crystal
Figure 4.29: Sample sock in water for 30 minute before treated by microwave.
85 Figure 4.30 (a) below showed the condition of the sample after treated with medium heat by microwave. After 27 s in the microwave the sample started to burst and had broken along the interface of andalusite grain and matrix, also in the matrix area.
Compare the dry sample, wet sample break faster almost double time. In addition, the result from transmit light microscopy provided the evidence of more facture along the interface between particle and matrix in the rock. Fig.4.30 (b) The Intergranular fracture in the ore.
a Breaking boundary
b
Breaking
boundary Breaking boundary
Figure 4.30: The andalusite sample after treated in medium heat by microwave. (a) Rock sample broke along the interface of the crystal and matrix. (b) Micro cracks at the interface between andalusite crystal and matrix.
86 4.6.2 (c) Wet Sample Treated in Low Temperature
The photograph and the micrograph of sample which is sock in water for 30 minute before treated in low heat my microwave show in Figure 4.31.
a
Andalusite crystal
Figure 4.31: Sample before treated by microwave.
Figure 4.32 established the result of the sample after treated in low heat by microwave. The sample burst in 3 min 25 s after place in the microwave oven. Rock break down in the matrix area and show a good result of broken along the interface of andalusite particle and matrix Fig. 4.32(a).The intergranular existing around the particle in most of the crystal. In comparison to the treatment in low heat by microwave with dry sample, this one present show a good result of breaking the particle and also save more energy due to the time to take the rock to break is less than dry sample.
87 a b Crack Crack
Crack
Figure 4.32: Crack along the interface between andalusite crystal and matrix.
4.7 Liberation and Separation
From the grinding tested result showed in (part 4.4), the grinding process of 20 rpm hand been chosen for grinding the materials after treated by microwave. Moreover, according to the microwave treatment showed in (part 4.5), the application of wet samples with low heated had been selected for treated the rock. This selection due to the observation found that in low heat and wet condition obtained a nicely crack along the interface more than other temperature. Beside this after treat by microwave, the low heat did not cause the sample to break.
The 650 g rocks was sock in water for 30 min, and bring to treated by microwave with low heat (home microwave) for 15 min. After the treatment process the ore was bring to grind with 20 rpm rotation speed. In 15 min of grinding 70 % of the particle was liberated. The ore was then sieve and classify as the second product as shows in
Figure 4.33 and 4.34 below.
88
Figure 4.33: The production of andalusite after microwave treatment with +6.33 mm.
Figure 4.34: The production of andalusite after microwave treatment with +2.8mm.
89 4.7.1 Microwave Treatment Production Grade
After through the grinding and sieving the grade of andalusite had been improved from 26.81% Al2O3 to 37.79 % Al2O3. Tables 4.9-4.10 show the improvement of andalusite by chemical analysis.
Table 4.9: Grade of andalusite bearing rock before separation.
Chemical Composition Wt (%)
SiO2 62.98
Al2O3 26.81 K2O 4
Fe2O3 4.79
Na2O 0.1 CaO 0.13 MgO 0.15
TiO2 0.68
Table 4.10: Grade of Andalusite bearing rock after separation.
Chemical Composition Wt (%)
SiO2 48.49
Al2O3 37.79
K2O 4.19
Fe2O3 8.29
Na2O 0.11 CaO 0.17 MgO 0.13
TiO2 0.42
90 CHAPTER 5
CONCLUSION AND FUTURE WORK
5.1 Conclusion
According to the experimental works, the study can be concluded into three major parts which are characterization of raw material, grinding study for liberation of andalusite minerals, and grinding study for liberation of andalusite mineral with the help of microwave treatment.
5.1.1 Raw Materials Characterization
Raw materials characterization is a crucial part to evaluate the natural resource for the future processing for any industrial application. Based on the study that have been done, the andalusite bearing rock from Sungai Cerul occur as sedimentary deposit, and andalusite crystals were obviously observed embedded in phyllite. The grade of andalusite bearing rock is approximately 49.13% Al2SiO5, and the grade of andalusite crystal is 73.35% Al2SiO5. Due to the high percentage of andalusite, this deposit has the potential to be exploited for its value. The grade of andalusite in Malaysia higher compare to andalusite from China. In China the andalusite is 30.02% Al2SiO5 (Zhou and
Zhang, 2011) . South Africa has highest grade of andalusite in the world which is varies from 82.59% Al2SiO5 to 95.30% Al2SiO5 (Overbeek, 1989).
91 Andalusite from Kemasik occurred in a similar geological environment with Sungai
Cerul. The crystal of andalusite disseminated in phyllite as host rock. However, the occurrence of andalusite mineral in Kemasik was affected by high weathering and alteration. Therefore, there is no specific andalusite crystal shape in host rock and the grade of Al2SiO5 slightly lower which is 40.81%. More importance factor is the beneficiation of andalusite in current technology depends on the andalusite crystal. For this reason, this deposit cannot be exploited for the time being due to the difficulty in beneficiation and concentration.
5.1.2 Grindability of Andalusite Bearing Rock
The experimental works on grinding performance on andalusite bearing rock from Sungai Cerul indicated that the optimum rotation speed of the rod mill to liberate the andalusite mineral from the host rock is at 20 rpm for 40 minutes. At higher speed,
30 rpm for 40 minutes will damage the crystal and lost to the waste. Whereas at lower rotational speeds of 10 rpm for 40 minutes will not efficiently break the rock for liberation due to the lower energy.
The liberation and separation of andalusite from the host rock managed to improve the grade of andalusite from 40.81% to 53.95% Al2SiO5. This improvement cannot lead the final grade to be commercialized due to the grade is not up to the standard as shown in
Appendix B. Other methods such as Dense Media Separation, Froth Flotation, Acid
Leaching and Magnetic Separation might be useful for future improve the grade of
92 andalusite. As reported by (Zhou and Zhang, 2011) froth flotation able to upgrade andalusite ore from 30.02% to 89.74 % Al2SiO5 in China.
5.1.3 Grindabilty of Andalusite Bearing Rock after the Microwave Treatment
Liberation of andalusite from the host rock very much improved when the sample was treated by microwave. This is due to the effect of microwave in breaking the interface between andalusite crystals and the host rock. Besides that time consumed for the grinding was also shorter than the grinding without treatment. It took only 15 minutes to liberate the crystal at 70% liberation compared to the grinding of sample without microwave treatment which took 45 minutes for 60% liberation.
Moreover, andalusite bearing rocks broke along the interface more effective with the treatment with low temperature in wet condition. When the sample was socked in the water, the interface between matrix and crystal become weak and easily breaks after microwave was applied. Due to the different density between andalusite crystal and matrix, treatment in high temperature and medium temperature lead sample broke along the matrix more than the interface.
Furthermore, the microwave treatment improved the liberation process and brings to improve the grade of andalusite from 42.58% to 60.02% Al2SiO5.
93 5.2 Suggestion for Future Work
Generally the liberation and separation of andalusite crystal from the host rock can be improved by the help of microwave. However, detailed of microwave effect on the breaking of the interface needs to be study in detail with other parameter such as socking in oil and other media.
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99 LIST OF PUBLICATION
1. Sophea Seng, Hashim bin Hussin, Kamar Shah Ariffin, Sasaki Keiko, Bun
Kimgun. Characterization of andalusite from Terengganu Malaysia as refractory
mineral for industrial application. International Conference IC-NET 2015, 27th
Feb- 2nd march 2015.
CHARACTERIZATION OF ANDALUSITE FROM TERENGGANU OF MALAYSIA AS REFRACTORY MINERAL FOR INDUSTRIAL APPLICATION
Sophea Seng1, a, Kamar Shah Ariffin1, b, Sasaki Keiko2, c, Bun Kimgun3, d , Hashim bin Hussin1,*, 1 School of Materials and Mineral Resources Engineering, Engineering Campus, USM, 14300 Nibong Tebal, Penang, Malaysia 2 Department of Earth Resources and Engineering, Faculty of Engineering Kyushu University, Japan 3 Department of Geo-resources and Geotechnical Engineering, Institute of Technology of Cambodia, Cambodia [email protected], b. [email protected], c. [email protected]_u.ac.jp, [email protected], *[email protected]
Abstract
Potential economic occurrence of deposit that rich with andalusite bearing mineral
(Al2SiO5) within metasedimentary rock formation near Kemasik, Terengganu has been investigated. The characterization of andalusite deposit is crucial when determining their composition and processability. In this research, the characterization of andalusite raw materials have been investigated through X-ray diffraction (XRD) analyzed with X’pert High Score, X-ray Fluorescence (XRF),
101 and Scanning Electron Microscopy (SEM) equipped with EDX for mineralogical analyses. XRD analysis of the sample indicated that andalusite contains approximately 76.1% along with other mineral such as quartz 12.4%, sillimanite 5.2%, magnetite 3.8%, corundum 1.5% and wollastonite 1%. Result from XRF analysis showed the percentage of Al2O3, SiO2, K2O, Fe2O3, NaO2, and CaO, MgO and TiO2 are 46.14%, 46.47%, 4.05%, 2.27%, 0.30%, 0.21%, 0.18% and 0.16% respectively. SEM-EDX observation revealed the present of fine iron oxide interlocked with andalusite minerals. Traces of rare earth bearing mineral mainly monazite occurred within a size range 10-100 μm were also identified. Rutile often found occurred as disseminated mineral in a flaky shape within a size larger than 220 μm in wide and 50 μm in leng.
Keyword: Andalusite, Sillimanite group, Refractory mineral, Metasedimentary
101
APPENDICES
APPENDICES A
Appendix A1: Loss on ignition data from Sugai Cerul area
mass (g) Loss of Mass (g) Sample before ignition Average(%) after ignited ignited (L.O.I) %
A 23.73 23.51 0.90 B 36.02 35.82 0.55 0.64 C 43.53 43.33 0.47
Appendix A2: Loss on ignition data from Kemasik area
Average mass (g) Total Mass (g) Loss of Sample before Average after ignited ignition ignited (%) (L.O.I) % 26.92 26.87 A1 28.35 28.29 0.173333 41.51 41.46 21.67 21.64 A2 28.58 28.54 0.132092 25.45 25.42 21.66 21.61 A3 28.58 28.53 0.20075 25.45 25.4 0.19 28.01 27.81 A4 29.35 29.28 0.403744 42.52 42.41 26.91 26.87 A5 28.36 28.3 0.152198 41.5 41.46 26.91 26.88 A6 28.35 28.3 0.12004 41.51 41.48
APPENDICES B
Appendix B1: Andalusite Standard for Industrial use in cars lining
Chemical Standard Andalusite composition (%)
SiO2 37
Al2O3 60.60
TiO2 0.27
Fe2O3 0.95 CaO 0.1 MgO 0.15
Na2O 0.08
K2O 0.34 Loss on ignition 0.1
Appendix B2: Standard Andalusite Bricks
Standard andalusite bricks
Type 1 2 3 4 Fe O 1.06 0.99 2 3 0.97 0.96 Firing Temperature 1480 1280 (ºC) 1320 1300 Co-resistance Good Little resistance