The Umbilin coal field (also Oembilin) is the most important coal field of central Sumatra and one of the most productive coal fields of the colonial Netherlands East Indies, located on the western coast of Sumatra about 165 km from Emma Haven (the harbour of Padang). The discovery of the coal seams dates from 1868, when the mining engineer De Greve found outcrops in the river Umbilin; exploitation began in 1892 after the construction of a most difficult railway from the mine to the harbour of Padang, and production reached its maximum capacity of 600,000 tons per year in 1916. The Umbilin coal field is included in this wiki because it is the principal coal-mining operation of the colonial Netherlands East Indies, and accordingly the comparative benchmark against which the disappointing Atjeh coal occurrences were assessed.
The 1868 De Greve discovery
Van Bemmelen’s account of the 1868 discovery reads:
“The discovery of the coal seams dates from 1868 when the mining engineer DE GREVE found outcrops in the river Umbilin.”
The 1868 discovery by De Greve is the founding episode of the Umbilin coal industry, and it places De Greve — who is also named (alongside Menten and Tromp) among the first generation of geologists to study the natural oil wells of the East Indies after the 1859 Pennsylvania oil boom — at the head of the documentary sequence of central-Sumatran coal exploration. For the full account of De Greve see the entry on De Greve.
Geology and reserves
The Umbilin coal fields belong to the Eocene formation, composed of sandstones, clay shales and conglomerates, in which are intercalated 3 coal seams A, B and C, respectively 2 m, 1 m and 6 to 10 m thick. They occur at a mutual vertical distance of 30 m, and dip 12° East. Only the A and C seams have been worked. The total reserves in the area of about 20 sq km have been estimated at more than 200 million tons, distributed across five fields: the Sungei Durian field (93 mill. tons), the Sigalut field (80 mill. tons), the Parambahan coalfield (in exploitation), the Tanah Hitam coalfield, and the Sugar Terrain.
Production history
The exploitation of the Umbilin coal field began in 1892, after the construction of a most difficult railway from the mine to the harbour of Padang. The railway track had to pass the mountain range of the Barisan, about 900 m above sea-level; on account of the steep gradient, rack-rail locomotives had to be used. The first two years’ production remained below 200,000 tons a year; then it rapidly increased, in 1903 being 300,000, in 1907 400,000 tons, in 1911 500,000 tons, reaching its maximum capacity of 600,000 tons in 1916. The production consisted of 60 % lumps and 40 % small coal. The A-seam is stoped with the long-wall system; the very thick C-seam is worked with the long-wall system for thick seams, divided in benches of moderate thickness, usually 4 benches of 2 m thickness. The empty stopes are refilled by sand by means of the hydraulic-filling method.
Coal quality
The Umbilin coal is generally stratified and contains sometimes fragments of resin. A combined ultimate and proximate analysis gave the following figures:
- Carbon: 73.05 %
- Hydrogen: 5.22 %
- Oxygen and nitrogen: 12.72 %
- Sulphur: 1.97 %
- Ash: 3.17 %
- Moisture: 3.87 %
- Volatile: 41.05 %
- Fixed carbon: 51.91 %
- Calorific value: 6970 cal.
- Coke-buttons: lustrous, baked.
Significance for Atjeh
The Umbilin coal field is significant for the encyclopedia of Acheh history because it is the principal coal-mining operation of the colonial Netherlands East Indies, and accordingly the comparative benchmark against which the disappointing Atjeh coal occurrences were assessed. Van Bemmelen’s summary judgment on the Atjeh coal exploration — “Several explorations for coal have been made in the northern part of Sumatra (Atjeh and Dependencies) but the results were disappointing, as large quantities of coal have not been discovered” — is implicitly a comparison with the Umbilin coal field, where large quantities of coal had been discovered and successfully mined. The contrast between the productive Umbilin field (with its 200-million-ton reserves and its 600,000-ton-per-year peak production) and the disappointing Atjeh coal occurrences (with their thin seams of “impure coal of a poor quality”) is the central fact of the colonial coal geography of northern Sumatra, and it accordingly determined the shape of the colonial coal-mining industry on Atjeh-relevant territory (the Kinandam-Sumatra Mijnbouw Mij. concessions at Bukit Durian, Bukit Pulai and Sarik, which produced only 2,000 tons over 1917–1927 for use at the Salida gold mine).
See Also
- Acheh
- Coal in Atjeh
- De Greve
- Emma Haven
- J. H. Menten
- J. Zwierzycki
- Kinandam-Sumatra Mijnbouw Mij.
- Padang
- Salida
- S. W. Tromp
- Van Bemmelen’s The Geology of Indonesia (1949)
- 1868
- 1892
- 1916
Source
The Geology of Indonesia, by R. W. van Bemmelen, Vol. II: Economic Geology (The Hague: Government Printing Office; Martinus Nijhoff, 1949), pp. 57–58 (Umbilin coal field discovery, geology, reserves, production, and coal quality).