A paper inspecting key levers recognized for slope steepening in Rio Tinto Iron Ore’s Pilbara pits
Rio Tinto Iron Ore has recognized that the excessive wall slope angles in its Pilbara open pits to this point are usually conservative, as a lot of the wall publicity is constructed to plan and is with out main wall efficiency points. This design conservatism has largely been because of gaps in orebody data and layers of conservatism within the design strategy. As mining footprints and crests turn out to be extra constrained and extra mining is happening beneath the groundwater stage, strong methodologies to steepen and safely handle slopes have turn out to be vital – to help waste motion discount, improve ore supply and establish high-risk areas. A undertaking commenced to establish the methodologies required to confidently steepen pit partitions utilizing chosen open pits as preliminary circumstances for evaluation and trial. The undertaking leveraged off trade greatest observe to establish factors of conservatism and discover levers within the design pathways that might enable for vital will increase in inter-ramp angles to be achieved with out undue danger.
An intensive set of generic analyses was undertaken to know the sensitivity of inter-ramp slope stability within the pits to varied elements, the primary ones being: the presence of comparatively robust layers within the weaker stratigraphic items and the proportions of robust supplies throughout the stratigraphic unit; the influence of inter-ramp slope top in numerous supplies, bedding dip angles and obliqueness of bedding strike relative to the slopes; the definition of the disturbance zone behind the pit slope; using numerous slope stability evaluation strategies in 2D and 3D; and the radius of curvature of pit slopes. This allowed for a strong evaluation and design strategy to be developed and for preliminary indication of potential optimum slope angles to be achieved. An in depth re-assessment of rock mass domains and properties on the take a look at websites was then carried out and stability analyses performed for the aim of figuring out optimum slope angles and the batter-berm geometries that might help these. This resulted within the inter-ramp angles within the preliminary focus pits being considerably steepened. This paper presents an outline of the strategy developed and the important thing levers recognized for slope steepening in these Pilbara Iron Ore pits.
