The Mt Leyshon Gold Mine is located 30 kilometres south of Charters
Towers in Northern Queensland. The current open cut mine has been in
operation since 1986. In 1992 a feasibility study was completed that recommended an increase
in production to over 240 000 ounces of gold per year. This proposal
required an upgrade of the processing plant to five million tonnes per
year, and an enlarged mining fleet to provide additional ore, and to meet
the increased waste removal requirements. The implementation of the mine expansion program during 1993
required the Life of Mine plan to be extensively revised. This required
the assessment and management of potential risks associated with the
mine design. The updated geological model using the 1992 drilling results along
with the actual contract mining and processing costs were used to
establish a series of nested optimised pit shells. The total and incremental
quantities and costs were then analysed to determine a suitable pit
perimeter. The pit and phase plans were then created and used to devise a
staged development plan. The block layout plans for each bench were
then established from which a detailed life of mine production schedule
was created.