Grade Control Strategies and Reconciliation Procedures at Kidston Gold Mine, North Queensland

The large, low grade, Kidston Gold Mine in North Queensland has achieved outstanding economies of scale and profitability. The total mineable ore reserve including mined to-date (as at December 1993) was 70.75 million tonnes at 1.54 grams gold per tonne. After nine years of mining, grade control mine production routinely reconciles against mill production and ore reserves to within five per cent of contained gold. The grade control system developed at Kidston is examined in detail, with emphasis on the geological thinking behind the strategies, as well as the development and application of a computerised, graphical production control and reporting system. Reconciliation procedures and results are explained, illustrating the success of geostatistical methods, as a risk management tool, in both ore reserves and production grade control.