engleski

Life cycle inventory of underground mining of bauxite: A case from Bespelj mine in Bosna and Herzegovina

Life cycle analyses of the metals require original mining data that can be related to the ore type and quality, type of ore body, its surrounding (geology, hydrology, topography), mining method, technology, and significance to the local community. Original mining data are difficult to obtain and there are uncertainties related to data reliability. Ideally, the inventory should be transparent, open and enable the modelling. The objective of this research is to give the life cycle inventory for underground bauxite mining. The inventory is based on realistic data collected during the three years of mining in Bešpelj Mine near Jajce. Time scale analysis and statistical analysis of data enable the modelling of the inventory for different outputs of ore. Additionally, the inventory from this research can be used for the LCAs of underground mining in similar production circumstances. Geological exploration of bauxites in the area of Jajce is started in 1955. and yielded many interesting geological findings on underground bauxite deposits. Bauxite ore bodies in Bešpelj, as other numerous sedimentary bauxite ore bodies in the area of Jajce, originated during the emersion phase of the long-lasting Cretaceous marine carbonate sedimentation, now known as area of the Internal Dinarides. These bauxites occur within the shallow-marine succession of carbonate rocks (limestones and carbonate clastics), which are present in the footwall and the hanging-wall of the ore bodies. In the footwall, karstified Middle Cretaceous limestones predominate, while in the hanging- wall carbonate breccias and calcarenites alternate. The underground system of Bešpelj is tectonically complicated. The terrain is well developed, between river canyons (as low as 310 m) and mountains heights (above 1400 m). The climate is moderate continental with abundant winter precipitation. Average summer temperature is 20C, and the winter extremes go below -20C. The underground abundant in water communicates well with rivers Vrbas, Pliva, Ugar and various creeks. The surface of Bešpelj area is covered with pine forest and grassland (pastures) and is poorly populated. The roads are connecting well the mines with town and other populated places. The bauxites of Jajce area are boehmite deposits of excellent quality, well explored, high in aluminum oxide and low in silica content. The production in Bešpelj is ongoing since 1958 (except interruption during 1991- 2005 due to war and its consequences).49 The method of mining is sublevel caving, both, with leaving of the empty spaces and with collapsing of the caved space. The extraction method is drilling and blasting, load and haul with pneumatic engine load shovel. Underground transport includes trolley-cart, gravity transport, and DC (battery) rail transport to the surface where the ore is gravitationally loaded into the trucks. The mine is supplied with compressed air (for the load shovel and pneumatic drill/hammer) from compressor station at the surface and underground compressor tanks. For the transport of miners from Jajce town the bus and shuttle transport is used. The mining company is well integrated in society, contributing to social and economic development of the area.

LCI, LCA, Underground mining, Bauxite, Environmental impact assessment

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