MLN 955 Gove Annual Report for the period 30 May 2013 to 29 May 2014

Abstract

During the anniversary period 30 May 2013 to 29 May 2014, Rio Tinto Alcan mined approximately 7.5 million dry tonnes of bauxite at the Gove mining operation. An aerial light detection and ranging (LiDAR) topographic survey was completed in June 2013 for the Gove peninsular. Grade control drilling was undertaken on the main plateau. The 2013 drilling was designed to infill 200 m2 spaced holes to 50 m2 spaced drilling. A total of 2,152 grade control vacuum drillholes for 7,693.5 m and 29,965 samples were completed. The 2013 Mineral Resource and Ore Reserve estimates were completed during the period by Snowden Mining Industry Consultants (Snowden 2014a and 2014b) and included approximately 80 percent of the 2013 drillholes. The derivation of the Mineral Resource from the total unconstrained Mineral Inventory is a total Inferred, Indicated and Measured classification of 194.9 Mt at 49.7 percent Al2O3 and 5.6 percent SiO2. The Mineral Inventory includes resources in 'exclusion zones' that are currently not mineable due to environmental and infrastructure reasons, but could be mineable in the future. The Mineral Resource was calculated with no block grade cut-off, but within a bauxite thickness envelope of at least 1 m inside a plateau edge buffer of 25 m. 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 are 150.1 Mt at 49.3 percent Al2O3 and 6.0 percent SiO2.