Coal Resources of the Baja Talamanca Area of Costa Rica

Abstract

A total of 17 million MT of subbituminous C and B coal had been evaluated to be present in the three sub-areas of the southern part of Baja Talamanca coal field (Uatsi Project); 8.7 million MT are classified as proven (measured) reserves. Within the northern sub-area of the Carbon Volio River basin, 2.6 million MT, with a thickness of 1.5 m, are present in the V-9 coal seam. Around 2 million MT are classified as proven reserves in an area of 1.2 km². The coal-bearing sequence is folded in an asymmetric, much faulted anticline. Some 3.1 million MT, with an average thickness of 0.95 m, in the V-7 of the eastern sub-area of the Carbon Volio River basin, cover an area of 1.7 km². Approximately 1.9 million MT of the total coal estimates are proven reserves. The coal-bearing member dips 10–20°. Underground mining will be needed to recover most of these resources. In the western subarea of the Carbon Volio River basin, 11.3 million MT are estimated to be present in the V-1 and V-9 Nueva coal seams. The lower bed (V-1), with a thickness of 0.95 m, has 5.1 million MT, of which 1.8 are proven reserves. The upper bed, 140 m higher than the V-1 bed, has 6.2 million MT with an average thickness of 1.5 m, of which 2.9 million MT are proven. The V-9 Nueva coal bed has an overburden ratio of 20:1 or less in an area of 0.4 km², where coal can be recovered by open pit methods. Proven reserves are calculated within a radius of 0.25 km from outcrops or boreholes. Total reserves are calculated within a radius of 0.5 km from known points of observation. A total of 37 measured outcrops and 20 boreholes were used to derive these resource figures.