MLN 955 Gove Annual Report for the period 30 May 2014 to 29 May 2015

Abstract

During the anniversary period 1 June 2014 to 31 May 2015, Rio Tinto Alcan mined approximately 7.1 million dry product tonnes of bauxite at the Gove mining operation. Grade control drilling was undertaken on the Main Plateau. The 2014 drilling program was designed to infill 200m2 spaced holes to 50m2 spaced drilling to move resource estimation in those areas from indicated to measured. A total of 4,177 grade control vacuum drillholes for 12,868m and 39,882 samples were completed. The 2014 Mineral Resource and Ore Reserve estimates were completed during the reporting period by Rio Tinto Alcan Resource Geology Team in Brisbane and utilised the same drillhole data - resource model as used in the 2013 estimation. Mineral resources are reported as at the 31 December 2014. The total 2014 Mineral Resource (exclusive of Reserve), including Inferred, Indicated and Measured classifications, is 52 Mdpt at 49.4 percent Al2O3 and 6.3 percent SiO2. The Mineral Resource was calculated with no block grade cut-off, but within a bauxite thickness envelope of at least 1m inside a plateau edge buffer of 25m. Although no cut-off has been applied to the model blocks, a mineralised bauxite envelope with a threshold of less than 12.0 percent SiO2 and greater than 40.0 percent Al2O3 was applied. The Ore Reserves estimated from the Mineral Resources, as at the 31 December 2014, are 146.1 Mdpt at 49.4 percent Al2O3 and 5.8 percent SiO2.