3D Modelling for Kumba Iron Ore’s New Kolomela Mine
Kolomela Mine, previously the Sishen South Project, has proven to contain numerous economic prospects over the last decade. Tect’s involvement at Kolemela began in 2011, when we were contracted to map, structurally analyze and 3D model the Leeuwfontein and Kapstevel North prospects. Tect’s work at Kolomela continues to date, with 3D models of Kapstevel South, Klipbankfontein, Wolhaarkop and Ploegfontein being addressed. Since 2011, Tect has mapped the rapidly deepening Leeuwfontein and Kapstevel North Pits, providing accurate structural data for the delineation of major structures, which are now firmly embedded within all 3D models and considered in annual design updates. In 2013, the quality of Tect’s 3D models, originally built in Micromine, ensured that these were used not only for Exploration planning, Geotechnical design and Hydrogeological analysis, but also for downstream MRE, thereby achieving the goal of fully-constrained 3D geomodels that are used by multiple departments.
In 2015, a decision was taken to construct all of Kolomela’s models in LeapfrogGeo. At the time of writing (March 2020), Seequent, in collaboration with Tect, were developing a workflow to host all projects and models on Leapfrog Central. This will allow for live tracking of projects and models throughout the mining cycle, including the addition of annual exploration data and assay results from daily production drilling. This constitutes the first roll-out of Leapfrog Central in South Africa.
During 2015-2016, the results of a regional geophysical survey, undertaken for hydrogeological purposes, became available. This study allowed the contacts of key lithological units to be modelled to a reasonable degree of accuracy, via geophysical data inversion by XPotential of South Africa, using GoCAD. This new data and the modelling of key contact surfaces initiated the development of a regional hydrogeological model by Tect, centered on Kolomela and covering approximately 55km along-strike and 40km across-strike. Constructed in Leapfrog, the model required careful planning and workflow development, as it had to incorporate detailed geology, in densely-drilled areas within Kolomela Mine, with regionally-interpreted, strike-extensive faults. The result is a seamless, cohesive model that was ultimately utilized by Itasca to accurately model water flow in and around Kolomela Mine.
At the same time, regional geophysical data were structurally interpreted by Tect and incorporated into a Maremane Dome-wide exploration model, in an analysis performed by XPotential, using GoCAD SKUA (Sub-surface Knowledge Unified Approach). This work, presented at the 35th IGC in Cape Town, highlighted exploration targets within the Manganore Formation across a strike length of 80km. In 2017, this work earned Tect a Silver Certificate of Recognition in the Innovation Category, from Kumba Exploration. Overall, mapping, analysis and fully-constrained 3D geomodelling at Kolomela Mine and Sishen Mine, combined with a regional structural interpretation of geophysical data, provide an ideal opportunity to resolve structural and lithological geometries and relationships at all scales. The results of Tect’s work on Kolomela Mine were summarized in a groundbreaking publication in Ore Geology Reviews, compiled with the assistance of numerous co-authors from both Kolomela Mine and Kumba Iron Ore’s head office:
The structural setting of mineralisation at Kolomela Mine, Northern Cape, South Africa, based on fully-constrained, implicit 3D modelling by Ian Basson, Sukey Thomas, Ben Stoch, Chris Anthonissen and Michael McCall of Tect, and Jean Britz, Stuart MacGregor, Hannes Viljoen, Deon Nel, Martin Vietze, Christian Stander, Jacques Horn, James Bezuidenhout, Tshele Sekoere, Charl Gous and Hein Boucher of Kolomela Mine and Kumba Iron Ore, in Ore Geology Reviews, 95 (2018).