1, Coal and coke resources in Indonesia
Indonesia is located in southeastern Asia and has abundant coal resources, with a resource volume of over 100 billion. Based on current production, it can be mined for 59 years. Most of the coal seams in Indonesia come from the Paleogene and Neogene, and are buried shallowly. Among the proven coal reserves, anthracite and bituminous coal account for 68%, while sub bituminous coal and lignite account for 32%. Almost all coal in Indonesia is mined open-pit, with 91% coming from East Kalimantan and South Kalimantan, and 9% from the southern part of South Sumatra Island. Due to the low sulfur and ash content characteristics of Indonesian coal, it is considered an ideal coal blend for Chinese coal. Indonesia is China's largest importer of coal.
The main coal bearing basins in Indonesia are distributed in the central and southern parts of Sumatra Island, as well as the eastern and southern parts of Kalimantan Island. These main coal bearing basins are the South Sumatra Basin, Central Sumatra Basin, Kutai Basin, Barito Basin, and Basia Basin.
Figure 1 Distribution map of coal bearing basins in Indonesia
1- Aceh Barat; 2- Central Sumatra; 3- South Sumatra; 4- Guru; 5- Wurong Kulong; 6- South Java; 7- West Java; 8- Ke Tun Gao; 9- Meravi; 10- North Tarakan; 11- Berau; 12- Warehouse platform; 13- Barito; 14- Brazil; 15- Asen Asen; 16- South Sulawesi; 17- Sarawati; 18- Bintouni; 19- Bambarai; 20- Aki Mingjia; 21- Grandmother's house; 22- Jayapura - Seratan
According to the BP World Energy Statistical Yearbook, as of the end of 2017, Indonesia's proven coal reserves were 25.598 billion, accounting for 2.2% of the world's proven coal reserves, with a reserve to production ratio of 49. Among them, the reserves of anthracite and bituminous coal are 17.326 billion tons, and the reserves of sub bituminous coal and lignite are 8.247 billion tons. According to the statistics of the Indonesian Coal Industry Association, the coal resources in Indonesia are 105.2 billion tons and the reserves are 21.1 billion tons, as shown in Table 1.
Table 1 Coal Resources and Reserves in Indonesia
2, Characteristics of Coal Quality in Indonesia
Indonesian coal has characteristics such as high moisture content, low ash content, low sulfur content, and high volatility. The metamorphic grade of Indonesian coal is medium to low, with ash content typically less than 10% and sulfur content typically less than 1%. In areas such as the southern part of the South Sumatra Basin, tectonic and volcanic activity have led to a significant increase in the grade of coal. The characteristics of coal quality determine that its combustion results in lower levels of atmospheric pollutants, making it more environmentally friendly.
Coal in Indonesia is mainly used for power generation. According to its calorific value, coal products can be classified into four grades: high quality, high quality, medium quality, and low quality. Indonesia's coal is mainly of medium and low grades, accounting for 62% and 24% respectively. Coal with a calorific value greater than 25.5MJ/kg accounts for only 14%.
In the air dry state, typical Indonesian coal has a calorific value of 23.9-30.2MJ/kg, volatile matter of 37.00% -42.15%, and low sulfur of 0.10% -0.85%; The calorific value of lignite is 18.2-24.4MJ/kg, the volatile matter is 24.10%~48.80%, and the sulfur content is 0.10%~0.75%.
The coal quality of products produced by different islands varies. The coal quality of Muba Port in central Sumatra Island has a calorific value of 21.6-24.2MJ/kg, a total moisture content of 33% -37%, internal water content of 13% -15%, ash content of 4% -10%, and sulfur content of 0.30% -0.6%. In the northern part of Kalimantan Island, the calorific value of coal is 24.3MJ/kg, the total water content is 19%, the internal water content is 16%, the ash content is 2%, and the sulfur content is 0.6%. In the southern part of Kalimantan Island, the calorific value of coal is 28.4-33.2MJ/kg, the total moisture is 10% -12%, the internal water is 4% -9%, the ash content is 3% -5%, and the sulfur content is 0.3% -0.9%. Overall, the quality of coal produced in Kalimantan Island is generally better than that in Sumatra Island.
