OCENA STOPNIA ROZPOZNANIA I BAZY ZASOBÓW SUROWCOWYCH NIEZAGOSPODAROWANYCH ZŁÓŻ RUD CYNKU I OŁOWIU OBSZARU GÓRNOŚLĄSKIEGO WEDŁUG NOWYCH ZASAD DOKUMENTOWANIA

Abstract

EVALUATION OF THE ASSESSMENT AND THE RESERVES OF UNDEVELOPED UPPER SILESIAN ZINC-LEAD ORE DEPOSITS USING THE NEW ASSESSMENT PRINCIPLES

Abstract. At the beginning of the XXIst century the domestic Zn–Pn ore mining industry has reached its final stage of existence. Recently, the only operating Zn–Pb ore mine in the Upper Silesia region is the Olkusz-Pomorzany enterprise. The perspective areas for future development are peripherial parts of the Olkusz ore clusters and the Zawiercie ore cluster, where assessment drillings have already been completed. In order to evaluate the ore potential of these areas the new assessment principles were implemented in 2006, which took into consideration the predicted, nest-like geometry of the orebodies. In the existing assessment reports the reserves of Zn–Pb ores were calculated with the Boldyriev polygonal method and the assessment category depended on the density of drilling grid. However, such an attempt caused significant overestimation of the reserves of uncontinuous peripherial orebodies. Thus, in the supplements to assessment reports for undeveloped deposits completed in the years 2007–2008 the boundaries of orebodies were drawn using the extrapolation of data obtained from the positive wells. Precisely, the particular distances were calculated from the autocorrelation radii (the range of influence of given information) basedupon the geostatistical variability models of exploited Pomorzany and Balin-Trzebionka ore deposits. From these models the boundaries of orebodies were taken as circles of radii 37.5 and 75.0 meters. The assessment categories of the reserves were dependent on the positions of orebodies in the lithostratigraphic column of the ore series. The main ore zone = the main assessment level (DK1) was a part of the Ore-bearing Dolomite corresponding to the Górażdże Beds. Within this horizon the ore reserves accumulated within the 37.5 meters circles were ascribed to the C1 assessment category and those within the 75.0 meters circles – to the C2 category. The reserves accumulated outside the main ore zone, were identified as C2 or D category if the 37.5 meters circles were considered. The ore reserves of undeveloped deposits estimated with this new methodology amounted some 66 Mt, which constitutes only 37% of reserves assessed with the old methodology. Consequently, in both the considered ore clusters only two undeveloped deposits: Gołuchowice and Laski can be regarded as adequately assessed. The remaining deposits require supplementary geophysical survey and additional drillings in order to improve data for their models and to evaluate their economic significance.