Phase Differentiated Cutoff Grades to Maximize Hard Rock Copper Production

摘要

Since 2015, Minera Los Pelambres has encountered new challenges due to the appearance of a high hardness rock body in its main ore phase. This is why every process involved in copper production has been forced to redefine ways of working and knock down paradigms. Short-term mine planning is no exception.Maximizing copper production is always mining businesses' main goal (along with security), but the way to achieve this goal must adjust accordingly with each mine's reality. That's how mine planning has come to question the paradigm stating that higher copper grades imply a higher copper production. This is due to the fact that copper production is a result of two other variables other than the grade: throughput and recovery. These two are precisely the variables that have changed the most since the appearance of this new mineralogy.For instance, in 2017 it is expected that two phases will provide the ore that will contribute to copper production in Pelambres: Phase 7 and Phase 10. The first, has high copper grades and high recovery, but it's extremely hard due to the presence of anhydrite, which implies low throughput. The second, has medium to low grades and low recovery, but soft rock. In other words, the complete opposite. So, is copper grade the key parameter to optimize copper production? No, at least not on its own.Pelambres's budget for 2017 has considered the use of phase differentiated cutoff grades in a way to enter to process those minerals that once were not considered due to its low grades, but now have been proved to contribute to a higher copper production. This methodology will provide 1 % to 3 % increase in copper production with no investing needed. Considering the copper market's current reality, this is a win-win.