The ability to integrate different services has been the key to SRK Consulting’s successful and ongoing relationship with one of our key clients in Chile, a major underground copper mine operator. Over the last four years, SRK has worked alongside the client’s own staff, helping them maximise the usefulness of geological data, while providing a combination of exploration program assessment, deposit modeling, structural geology, and open pit geotechnical design.
The first step was aiding the client in designing the collection and interpretation of geotechnical data from their own drill hole campaigns, exploring the geological surface. The aim was to identify mineralisation amenable to open pit excavation that could not be mined from the existing underground operations. This preliminary database served as the mine design parameters for the client’s engineering staff. Two mineralised areas were studied, one to the north of the existing underground mine and one to the south. Concurrent with the drilling program, SRK specialists in hydrogeology and environmental engineering conducted parallel studies of the site and integrated this information into the overall project database.
As part of the process in collecting the geological, geotechnical and structural information from the drill core, SRK trained client personnel in the procedures we employ for logging the drill core and techniques for orienting the structures present. SRK’s staff remained continuously in the field to aid in the collection of data and to supervise these activities.
Because the client’s obvious focus was on the existing underground operations, there was a lack of data regarding key geological structures and structure sets in the future open pit areas. The data SRK collected from the drilling campaigns greatly increased the information available and, with the help of alpinists, SRK geologists were able to aid the client in surface structural mapping. In addition, SRK mapped geotechnical structural windows in the underground workings bordering the north pit area. As a result, from the drilling campaigns, as well as surface and underground mapping, it was possible to prepare an integrated structural model for this area. Armed with this information, SRK specialists were able to study and model the effects of the possible interaction between the open pit and underground operations.
SRK’s close contact with the client revealed the need to study controls on the mineralisation in the area of the proposed northern pit, where the high grade mineralisation is more erratic and appears to occur at a greater depth than in the adjacent underground operations immediately to the south. Using Leapfrog 3D visualisation software, SRK modeled varying copper grades for the entire mine and exploration drill hole database. The results showed a clear correspondence between the location of structures oriented west-northwest and the northward continuity of the >1% copper envelope. SRK and the client’s geologists mapped these north-northwest structures on the surface. Future studies should clarify if these structures do, in fact, play the determining role in the distribution of the high grade mineralisation.
