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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 5, Issue 3, March 2015)

391

The Crucial Role of Coal for Coal-Fired Power Plants Affected

by the Geological Origin: South Korea

Yujin Jegal

1

, Thriveni Thenepalli

2

, Jiwhan Ahn

3

1

Department of Resources Recycling, University of Science & Technology, 217 Gajeong-ro Yuseong-gu, Dajeon, 305-350 Korea

2,3Resources, Environment and Materials R&D Center, Korea Institute of Geoscience and Mineral Resources/ Gwahang-no

124, Yuseong-go, Daejeon, 305-350 Korea

Abstract—The objective of this study was to investigate the key factors for the quality of coal used in operating coal-fired power plants impacted by the geological origin, particularly with the case study of Indonesian Coal used in South Korea. Growing demand of power generation for commercial benefits and industrial uses, coal is the major source of power

generation. Presently, South Korea is booming to

manufacturing all commercial products throughout the world. So the power generation is most important not only for South Korea, but also throughout the world. The world-wide distribution of coal depends on the geologic impact which affects the type and the quality of raw coal. Since, South Korea imports majority of bituminous or sub-bituminous coal from Indonesia, we studied Indonesian coal provided by Hadong Thermal Power Site Division of Korea Southern Power Co., Ltd. The quality of the sample was analyzed by the geologic origin of the sample site which affects the quality. Additionally, due to serious environmental problems from coal combustion waste dumping, recycling and recovery technology are necessary to prevent the landfill. The major advantage of this recycling technology is not preventing landfill and also recovery of critical rare earth elements and it is good scope for doing new research directions. Here, we presented some studies of rare earth elements associated with coal origin.

Keywords—Coal, Geological origin, Power generation, Quality Assumption, Critical rare earth elements

I. INTRODUCTION

After the Fukushima Daiichi nuclear disaster in Japan, the world has seen a declined interest in the building of nuclear power plants. Demand for coal is increasing due to a surge in demand for electricity, developments in power generation, and affordable prices of coal. This increase is especially prominent in Asia, and Korea is no exception [20]. The total global coal production by year shows that demand for coal rose from 4677 Mt in 1990, to 7608 Mt in 2011, and to 7380 Mt in 2012 [3].

Coal accounts for 29.9% of global primary energy and generates 41% of the world’s electricity.

It is also used in 70% of total global steel production [3]. Coal makes up 42% of electricity production in the United States, 15% in EU countries, 47% in Australia, 25% in Japan, 80% in China, and 85% in South Africa [2].

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 5, Issue 3, March 2015)

392

According to Korea Coal Association, bituminous coal used in Korea’s power plants is usually imported from Australia and Indonesia, and anthracite coal from Australia, Russia, and China. About 40% of the country’s low rank coal is imported from Indonesia. Although Korea Coal Association reported that the amount of imports dropped by 4.6% from 2,431 tons in November 2013 to 2,320 tons in November 2014, Korea is still dependent on low rank coal, and this is mostly comprised of inexpensive sub-bituminous coal [32].

This study explores coal quality (components, properties, etc.), which contributes to efficient operations of coal power plants, and factors that influence it in order to adapt to the increasing demand for electric power. As an example of low rank coal, the Indonesian coal (EK-coal) imported by Hadong Power Station is analyzed in terms of chemical composition and critical elements, along with geological factors that influence coal quality.

II. QUALITY OF COAL RELATED TO ITS ORIGIN AND WORLD DISTRIBUTION OF COAL

A. The genesis of Coal and its rank

A long and complex process is involved in the production of coal that is used for power generation in coal-fired power plants. Peat is formed after various organic materials grow and become buried over time. The geothermal heat and geothermal pressure arising from continuous diastrophism (diagenesis, metamorphism etc.) stimulate chemical changes, and eventually lead to the birth of coal[8]. Composed of both organic and inorganic compounds, coal is produced when more than 100 inorganic compounds are introduced into a mire [7]. The speed of production and growth varies with strata and geological conditions such as sedimentary basin, preservation of terrestrial plants, properties, and metamorphism. For this reason, there are significant differences in output conditions, properties, and components. Coal contains as many as 76 of the 90 naturally occurring elements of the periodic table, which is an indicator of its complex composition [7].

[image:2.612.92.522.414.644.2]

Coal is classified according to coal rank (Fig 1). Depending on the extent of coalification, the major coal ranks are peat, brown coal, lignite, sub-bituminous coal, bituminous coal, and anthracite.

Figure 1. Reserves and major uses of world-wide coal

According to the American Society for Testing and Materials (ASTM), bituminous coal can be further divided into low, medium, and high volatile, and anthracite into semi-, meta-, and graphitic.

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 5, Issue 3, March 2015)

393

Sub-bituminous coal is usually used in power plants because it has a high calorific value (4,600~6,400kcal/kg) and can be burned at temperatures higher than 2000 °C. Anthracite, with a low calorific value of 4500 kcal/kg, is used more often in homes. The factors determining economic variables of coal are the coal seam thickness, distribution size and coal rank. Since these factors are influenced by plate tectonics, geothermal gradient (temperature), structural stress (pressure), erosion, and ocean accessibility (sulfur) [6], it is important to understand the effects of the origin of coal on economic variables.

B. Critical Factors to determine World Coal Quality

Coal quality, which determines the efficiency of boilers in coal power plants, is assessed based on ash content, components, sulfur content, and moisture content [10]. The USGS report by Stanley P. Schweinfurth mentioned that coal quality is influenced by five types of geological and biological environments [7]. The first is plants. Plants form a peat, which is accumulated with water flowing in neighboring areas. The second is biological factors, including oxidation, acidity of water, and micro-organic components such as bacteria. The third is mire location and climate.

Mires located near rivers tend to contain more minerals, while those near the sea have more sediments as they are less influenced by floods. Thick coal seams are likely to have been formed in subtropics or tropical areas. Thin, discontinuous coal seams imply colder and less moist areas. The fourth is mineral material. When coal is first formed, minerals from the surrounding soil or mire are carried by water or wind. Mineralization occurs due to geological effects after coal formation, and this produces more minerals. The fifth is coalification. As temperature rises, there is a decrease in moisture and volatile materials, leading to the formation of higher rank coal. During coalification, the amount of organic materials decreases while fixed carbon increases. In this process, inorganic mineral materials are rearranged and undergo further mineralization[8].

Coal basins subject to the influence of the aforementioned geological and biological environments are well distributed around the world. High-ranking bituminous coal can be found more abundantly than low-ranking anthracite. Korea usually imports coal from countries such as Australia, China, and Indonesia. Ministry of Trade, Industry and Energy of South Korea announced the report about the development of technology for upgrading of high moisture low-rank coals.

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 5, Issue 3, March 2015)

394

In this report, they mentioned that coal imported from Australia has a higher ash content compared to that of China and Indonesia, in terms of coal quality. Indonesian coal can be classified into high calorie coal and low calorie coal. The former has low sulfur, low ash content, and high calorific value, while the latter has low sulfur, low ash content, low calorific value, and high moisture content. Also, coal from China is characterized by low sulfur content, low ash content, and high calorific value. Finally, Russian coal has low moisture, low sulfur, high calorific value, and non-uniform quality due to the presence of impurities.

C. World-wide Coal Reserves

In 2011, the proved recoverable global coal reserves was 981,530 Mt. Anthracite and bituminous coal made up the highest portion at 403,197 Mt, followed by sub-bituminous coal at 287,333 Mt, and lignite at 201,000 Mt [9]. This was a decrease compared to the 2010 proved recoverable global coal reserves of 1,003,788 Mt. Coal resources are widely distributed around the world, but proved coal reserves are concentrated in certain countries [4,2]. Coal basins can be found in 75 countries, and some of the larger reserves are in Asia [5] (Fig 2). The United States leads the world in coal reserves with 237,295Mt as of 2011, followed by Russia (157,010 Mt), China (114,500 Mt), and Australia (76,400 Mt) [5]. North Korea has an estimated 600 Mt of anthracite, bituminous coal, and sub-bituminous coal, while South Korea only has 126 Mt of sub-bituminous coal [9].

III. INDONESIAN COAL DISTRIBUTED IN EAST KALIMANTAN

[image:4.612.306.578.505.719.2]

D. Overview and Status of Coal in Indonesia

Figure 3. Indonesian Coal Exports, 2000-2009 (Source: Global Business Goude Indonesia-Energy & Mining)

Coal deposited in Indonesia mostly ranges from low rank to middle rank, namely Paleogene and Neogene coal. Coal rank in some coal basins has increased due to tectonic and igneous activity [11]. Many newly constructed power plants in Asia have adopted boiler technology for sub-bituminous and sub-bituminous coal, resulting in an increase in Indonesia’s coal exports from 200 Mt in 2008 to 387 Mt in 2012 [12] (Fig 3). Korea, which relies on Indonesia mainly for bituminous coal, saw a decrease in coal imports from Indonesia in 2014 compared to 2013, contrary to the general situation in Asia [22]. Indonesian coal is mostly sub-bituminous coal with high ash content and moisture, unlike Australia’s Paleozoic coal (Gondwana or Laurasia coal) or Africa’s bituminous coal [12]. Distinct stripes can be observed in Paleozoic coal, but not in Indonesia’s Cenozoic coal [6]. Indonesian coal can be broken down into lignite (58%), sub-bituminous coal (27%), bituminous coal (14%), and anthracite (0.5%) [11]. The larger coal basins are in Sumatera and Kalimantan Islands, which are home to various high rank and low rank coals with calorific values ranging from 5000 to 7000 cal/gr. Coal basins are also distributed in JAWA, Sulawesi, and Papua(Table I). In particular, low rank coal with low calorific values is located in the Maluku region [10]. Harvey E. Belkin et al. (2009) provided an explanation of coal ranks in Indonesia by period. They mentioned that bituminous coal was deposited in the Paleogene period, and sub-bituminous coal or lignite in the Neogene period. Among Neogene coals, coal in the South Sumatra basin attained higher ranks due to tectonic and igneous activity [11].

TABLEI

THE RESERVES OF COAL IN INDONESIA

Province Coal reserves in Indonesia

(ton) East

Kalimantan

Tanjung Redep* 5,000 Tanjung Bara 200,000

Bloro* 8,000

Loa Tebu* 8,000

Balipapan 60,000

Tanah Merah 20,000

South-East Kalimantan

North Palau Laut 150,000

IBT 70,000

Sembilang* 7,500

Air Tawar* 7,500

Banjarmasin* 10,000 South Pulau Laut 200,000 Satui*& Kelanis* 15,000

Sumatra Tarahan 40,000

Pulau Baai 35,000

Kertapati 10,000

[image:4.612.55.277.524.686.2]
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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 5, Issue 3, March 2015)

395 E. Coal Geology in East Kalimantan, Indonesia

Hadong Power Plant imports bituminous coal from Long Daliq, Long Iram, West Kutai, and East Kalimantan of Indonesia. We examines coal quality in Indonesia, and investigates geological activities that influence coal quality in the East Kalimantan region.

Indonesia’s coal basins can be largely divided into Arc-Trench (small coal deposit), Continental Margin (economical resources deposit, various thick coal deposit, bigger deposit), and Rift Valley(lowest rank and quality coal deposit) [6]. According to Alxander Horkel (1990), the Arc-Trench zone has a complex tectonic structure caused by geological structural changes and is contaminated by sediment detritus. Coal found in this basin has a relatively high rank, resulting from magma intrusion and tectonic stress. He mentioned that the Continental Margin (East Kalimantan), from which samples were obtained, was close to the Foreland Basin (South Sumatra) and had thick coal deposits (Fig 4).

The geological activity of coal not only affects basin size but also coal type and components. The Kutai Basin coal mine of East Kalimantan is close to the Central Kalimantan Range and Muller Mt, which are known for their history of complicated geological activities [14]. Since the study area is also nearby, it was assumed to have been under similar influences.

IV. QUALITY AND CRITICAL COMPONENTS OF COAL FROM LONG DALIQ,EAST KALIMANTAN,INDONESIA

A. Coal Geology in East Kalimantan, Indonesia

EK-Coal sample provided by Hadong Power Plant of Korea Southern Power was investigated in this research: this coal was imported from Long Daliq, Long Iram, West Kutai, East Kalimantan.

Table II shows the measurements for moisture, volatile material, fixed carbon, and calorific value, which were taken to determine the basic properties of EK-Coal.

Moisture content (ASTM D3173-73:30) was measured based on weight reduction after heating a 0.5-1g sample of 60 mesh or lower in vacuum or pure nitrogen atmosphere at

107±4℃ for one hour. Volatile material (ASTM D3175-77) was measured based on weight reduction after heating a 1g sample of 60 mesh or lower in an oxygen free

atmosphere at 950±20℃ for seven minutes. Ash content (ASTM D3174) was measured based on residue after complete combustion of a 1-2 g sample in oxygen at

725±25℃. Lastly, fixed carbon was calculated by subtracting the percentage of moisture content, volatile material, and ash content from 100%. The calorific value Q is usually obtained through thermal insulation (ASTM D2105-73) or isothermal method (ASTM D3286-73), but this study employed an isotopic analysis. XRF analysis and measurement of rare earth elements were entrusted to the Geoanalysis Center of Korea Institute of Geoscience and Mineral Resources. Rare earth elements were measured using alkali fusion, acid digestion, and ICP-MS.

TABLEII

THE QUALITY OF EK-COAL SMAPLE The result of Quality of EK-Coal

Moisture(%) 32.70

Volatile(%) 36.49

Ash(%) 1.18

Fixed Carbon(%) 29.93

Qvad(Kcal/kg) 4268.13

In general, low rank coal in Korea refers to coal with an ash content higher than 18%, sulfur content of 1.1%, and calorific value less than 5,350 kcal/kg [22]. In the above analysis, EK-Coal had a very low ash content of 1.18% and a very low calorific value of 4268.13 kcal/kg, thus satisfying the conditions of low rank coal.

[image:5.612.339.548.399.469.2]

B. Results and Discussion

Table III shows the XRF results for EX-Coal. In general, coal contains as many as 120 types of minerals.

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 5, Issue 3, March 2015)

396

Among these minerals, 33 are commonly found, and the majority is made up of 8 types [7]. The major composition of minerals in coal includes quartz (SiO2), Al-containing

soil minerals, calcite, iron-containing siderite, and sulfur-containing pyrite [14]. Unlike coal rich in Si and Al, EX-Coal has a high Fe2O3 content, and this can be traced to its

unique production environment. Research by Sri Widodo et al. (2009) on coal quality of a region close to the present study area revealed large mountain ranges such as the Central Kalimantan Range and Muller Mts. The high iron content was presumed to have resulted from the deposition of Cenozoic sediments and volcanic sediments [13, 14]. Orogenic phases dating back to the late Oligocene and Miocene periods were found near the coal basin [13]. During these periods, the Kalimantan region experienced deformation and uplifting, and there was an influx of volcanogenic clastics from the Central Kalimantan Mt [14].

TABLEIII

CHEMICAL COMPOSITION OF EK-COAL The XRF result of EK-Coal (unit:wt.%)

SiO2 2.40

Al2O3 16.85

Fe2O3 47.93

CaO 10.67

MgO 2.44

K2O 0.11

Na2O 0.23

TiO2 0.60

MnO 0.77

P2O5 0.04

Igloss 12.42

[image:6.612.323.564.114.313.2]

Fig 5. shows the concentration of rare earth elements in EX-Coal. Rare earth elements, known as critical resources of the 21st century, are key materials for hybrid cars, medical imaging devices (MRI, X-ray, etc.), LCDs, computer hard drives, wind power generation facilities, green technology, high-precision tools, night vision devices, and radar systems [16]. Neumann System Group, Inc. (NSG) succeeded in recovering fly ash from rare earth elements containing neodymium (Nd), yttrium (Y), and europium (Er). Fly ash was converted to high value-added critical metals through a purification process that costs less than USD 200 per ton. A total of 14 rare earth elements and critical metals were extracted, and fly ash was estimated to have a value of USD 400~750 per ton in the initial assessment. Various countries are actively researching the recovery of rare earth elements from fly ash, which is expected to be rich in rare earth elements and thus highly valuable. The REE content in EX-Coal was analyzed from this perspective.

Figure 5. The Rare Earth Elements Concentration of EK-Coal measure by ICP-MS (Red: Light REEs, Blue: Heavy)

V.V. Seredin and S.Dai (2012) and Ketris and Yudovich (2009) found that the average sum of rare earth elements and yttrium (Y) in coal was 68.5ppm [17,18]. Compared to average values for world coal, Hadong coal had a Ce concentration higher than the world average, and REE

concentrations ranging from 0.42 ㎍/g (Lu) to 103 ㎍/g (Ce). It also had a higher concentration of LREEs than HREEs. Geologically, coal is enriched in HREEs as they are compatible with silica minerals, but depleted in incompatible LREEs [19]. The results for rare earth elements in Table 3 show a high LREE concentration for Hadong coal. By comparing these results with the XRF analysis of Table 2, we can presume that smaller silica content leads to higher LREE and lower HREE concentrations.

Considering the tectonic activities that led to the formation of mountain ranges and volcanism, the sampling region is likely to have produced mafic minerals rich in Fe and Mg but not Si. Mafic minerals become weathered over time by wind and water, and are introduced into coal layers. After this process, incompatible LREEs are expected to have accumulated in silica minerals.

HREEs are found in less concentrated amounts in the earth crust, while LREEs are relatively more abundant. Due to their unique properties, they are being utilized in various applications [15]. The US Department of Energy designated five rare earth elements as critical materials in 2011. The designated elements were Nd, Eu, Tb, Dy, and Y. In the Hadong coal sample, Nd and Y were present in

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 5, Issue 3, March 2015)

397

In particular, neodymium permanent magnets are one of the strongest magnets in the world, and highly useful in powder metallurgy and sintering [15]. Yttrium is used in phosphors, added for shock resistance in glass or ceramics. Its other applications include fluorescent lamps, metal ally agents, camera lenses, and optical lenses [15, 16]. Coal basins with rare earth elements exceeding 1000 ppm can be found around the world, such as Russia’s Rettikhovka deposit (1141ppm), China’s Songzao deposit (2446ppm), and Mongolia’s Aduunchuluun deposit (5178ppm). Many studies are being conducted in this field.

V. CONCLUSION AND FUTURE WORK

Korea has been building more coal-fired power plants under the influence of the Fukushima Daiichi nuclear disaster, affordable coal prices, increased demand for electricity, and the 6th Basic Plan on Electricity Demand and Supply. Rapid changes in international energy prices and reorganization of the electricity market have led to power companies importing more low rank coal. This study was conducted to determine factors influencing coal quality, which is a key element in efficient and economical operation of coal-fired power plants, with a particular focus on geological factors. More specifically, this study examined factors that geologically affect the quality of raw coal. By analyzing the components of Indonesian coal imported by Hadong Power Plant and studying the geology of the region, a relationship was established between the geological origin and coal properties.

Coal quality is assessed based on ash content, sulfur content, and moisture content, which are largely influenced by five factors. A highly complicated process was involved in coal production and development of properties. Coal rank, ranging from low rank to high rank coal, depends on the extent of coalification. Economic variables are determined by plate tectonics, geothermal gradient, structural stress, and ocean accessibility, thus indicating the importance of the coal production environment.

This study analyzed the domestic coal market as well as the Indonesian coal supply. It was found that coal of various ranks is distributed across Indonesia. The XRF analysis of coal imported by Hadong Power Plant showed a high value for Fe2O3 (47.93%), and this was presumed to

be related to Cenozoic tectonic activities such as uplifting of mountain ranges and volcanic activities. Lastly, the

concentration of rare earth elements (from 0.42㎍/g (Lu) to

103㎍/g (Ce)) was considered uneconomical. Future work will include comparison with coal imported from other countries and analysis of coal ash concentration.

REFERENCES

[1] David, E., 2013. Fukushima: Impacts and Implications..

[2] Hans, W. S. 2014. The impact of Global Coal Supply on Worldwide Electricity Prices: Overview and comparison between Europe, the United States, Australia, Japan, China and South Africa. Report by the IEA Coal Industry Advisory Board.

[3] International Energy Agency, 2013. Coal Information 2013 Edition: Documentation for beyond 2020 files.

[4] Siman, W., 1993. Major Coalfields of the World. Published by IEA Coal Research.

[5] International Energy Agency(IEA), 2014. World Energy Outlook 2014: Executive Summary.

[6] Alexander, H., 1990. "On the Plate-tectonic setting of the Coal deposits of Indonesia and the Philippines", Mitt, österr. geol. Ges., pp. 119-133.

[7] Schweinfurth, S. P., 2009, "An introduction to coal quality, in Pierce, B.S., and Dennen, K.O., eds., The National Coal Resource Assessment Overview: U.S. Geological Survey Professional Paper 1625–F, Chapter C, 16".

[8] David, A. D., 1989. California's unique geologic history and its role in mineral formation, with emphasis on the mineral resources of the California desert region, USGS.

[9] Alseeandro, C., 2013. World Energy Resources 2013 Survey: Summary. Published by World Energy Council.

[10] Herminé, N., 2011. Expert systems and coal quality in power generation, IEA Clean Coal Centre.

[11] Harvey, E. B., Susan, J. T., James, C. H., Strucker J. D. and O'Keefe J. M. K., 2009. "Geochemistry and petrology of selected coal samples from Sumatra, Kalimantan, Sulawesi, and Papua, Indonesia", International Journal of Coal Geology 77, pp. 260-268. [12] Serene, L., 2013. Thermal coal-Meetings with Indonesian producers

in Global Research, Standard Chartered Bank.

[13] Addison, R., Harrison, R. K., Land, D. H. and Young, B. R., 1983. "Volcanogenic Tonsteins from Tertiary Coal Measures, East Kalimantan, Indonesia", International Journal of Coal Geology 3, pp. 1-30.

[14] Sri, W., Wolfgang, O., Achim, B., Reinhard, F. S., Koman, A. and Wilhelm, P., 2010. "Distribution of sulfur and pyrite in coal seams from Kutai Basin (East Kalimantan, Indonesia): Implications for Paleoenvironmental conditions", International Journal of Coal Geology 81, pp. 151-162.

[15] Jared, L. R. and Samuel, A. M., 2012. Rare Earth Elements: Procurement, Application, and Reclamation, SANDIA REPORT No. 2012-6316, Sandia National Laboratories.

[16] Marc, H., 2013. Rare Earth Elements: The Global Supply Chain, CRS Report for Congress, Congressional Research Service. [17] Ketris, M. P. and Yudovich, Ya. E., 2009. "Estimations of Clarkes

for Carbonaceous biolithes: World averages for trace element contents in black shales and coals", International Journal of Coal Geology 78, pp. 135-148.

[18] Vladimir, V. S. and Shifeng D., 2012. "Review Article: Coal deposits as potential alternative sources for lanthanides and yttrium", International Journal of Coal Geology 94, pp. 67-93.

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Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 5, Issue 3, March 2015)

398

[20] Gukjin, B., 2014. "Outlook of Coal-fired power plant market-Necessity enlargement of High efficiency and low pollution technology of coal", KISTI MARKET REPORT, Vol. 3 Issue 6, pp. 15-19.

[21] The Ministry of Knowledge Economy of South Korea, 2013. The 6th Basic Plan for Electricity Supply and Demand(2013-2027). [22] Sehyun, B., Hoyoung. P. and SungHo, Ko., 2013. "Economic

Evaluation of Coals Imported in Last 3 Years for Power Plant Based on Thermal Performance Analysis", Journal of the Korean Society of Combustion 18 No. 3., pp. 44-53.

Aknowledgement

Figure

Figure 1. Reserves and major uses of world-wide coal
Figure 2. (Unit: Mtoe) Global coal recoverable reserves by region (Source: World Energy Council 2015)
Figure 3. Indonesian Coal Exports, 2000-2009
Table III shows the XRF results for EX-Coal. In general, coal contains as many as 120 types of minerals
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References

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