Editorial

Applied geology plays a part in most phases of a mining operation, and different companies chose to emphasise geology at different stages. For some operations, the amount of geological input is relatively minor compared to the overall size of the mine and its production; however, for complex orebodies such as gold there needs to be strong geological input at multiple stages.

At the exploration stage for all minerals, geological input is expected, and this process is usually led by geologists. Once a discovery is confirmed, the (pre-) feasibility stages require geological input as the basis for reserves, mine planning, and cost and budget estimates.

For some, but certainly not all mines, the commitment to develop an operation marks the end of geological input except for some daily to monthly monitoring. If the grade is high and costs low, an operation can become quite complacent yet still may appear to be operating well and profitably. It is not until the end of reserves is in sight and mine closure is imminent that there is another surge of interest in geology and exploration. Of course in such a situation it can be quite difficult to suddenly engage a whole geological exploration team when closure is nigh.

There are better ways to apply geology during the life of a mine.

A different approach can be taken once a commitment to start an operation is made. This period might be an opportunity to develop a longer-term understanding of the deposit, set the framework for successful mining, and a platform for later near-mine exploration successes. Some well considered questions at this stage can set the scene for useful projects: ‘How does structure influence the location of the deposit? What are the host rocks before metamorphism and alteration and deformation? Why is the deposit here?’ All simple questions; all vital to the way the mine is developed and exploration is conducted.

Once mining commences any delay in early production is very expensive. If start-up is six months behind schedule because of geological difficulties this can mean a major call on working capital, or potentially mine closure. Having a top class mine geology team working closely with the exploration group to anticipate problems and have them answered very quickly can pay huge dividends. Alternatively, a new mine geology team that does not fully understand their orebody may take weeks and months to resolve important geological issues, e.g. ‘where has the ore gone?’; it is likely that the mine geology team at this early stage may know less about the orebody than does the exploration team, external consultants or active researchers. All can be asked to assist.

Regardless of how well the exploration group put together an orebody model, there should be much more to learn once the orebody is seen in the open pit and underground. Ideas on rock breakage, metallurgy, geotechnical properties and influences on the environment can all be refined as part of a holistic approach to orebody knowledge.

Access to open pit geology marks a phase where much new geological information becomes available, as does the transition to underground. Both occasions should be opportunities to revisit exploration in the district with improved geological models.

As the mine moves into a steady-state production phase, keeping a small but constant research group rarely stimulates long-term value, part of the reason being that the group is driven by ‘what can we find to do, or what would we like to do’ rather than ‘here is a major issue that requires resolution’. Instead of a steady-state in-house research effort, small campaigns are a productive way to answer key questions and should conclude with a period of exploration and/or application follow-up. A secondment of the best internal and external people into a short-term campaign is a very effective way to answer difficult question, keep the staff refreshed, and achieve some on-the-job training by learning from one another.

Geological input can be valuable at many stages during a mining operation, but the arrangement of that input and the type of team needs constant review and readjustment.

Neil Phillips & Simon Dominy

Editors

Applied Earth Science (TIMM A)