Techno-economic parameters related to the Vrshnik Cu-Au ore body, Buchim copper mine, Eastern Macedonia

Calculated ore-bearing coefficient in the Vrshnik ore body was 0.78%, meaning that within the ore body boundaries only 22% of mass is not mineralized somehow, which is highly compatible with remaining three ore bodies within the Buchim porphyry copper mine. The calculated value of variation coefficient (V) has shown value of 70% that is in the range of 43-100%, which displays that this ore body belongs to the third group of deposits with uneven mineralization. An average copper, gold and silver concentrations were determined as 0.305% Cu, 0.18g/t Au and 0.91 g/t Ag, respectively. Minimal economic content (MEC) within the Vršnik ore body, as represent of this kind of mineralization, was determined as 0.160% Cu. In similar manner was calculated the lowest copper boundary (cutoff grade), which have shown value of 0.138% Cu and thus allowing certain decrease of contents in exploited ore. Also, there were calculated so called copper monometal values, which included influence of the present gold and silver in the ore. Calculated copper monometal was set at relatively fair 0.399% Cu that represents solid mainstay for exploitation of copper in these low percentage ores. Calculated ore reserves in this particular ore body were 13 577 267 t of ore with 0.305% Cu, 0.18 g/t Au and 0.91 g/t Ag and increased mine life for additional 6 years