DILUTION, AN UNPREDICTABLE FACTOR
In the mining sector, dilution is defined as “all external material with grades lower than the cut-off grade that is inevitably mined with the extracted mineral.” In other words, it is the amount of waste material or below cut-off grade material that is mixed with the mineral during the stages of mining.
Dilution poses a major challenge in the fundamental steps of a mining project: planning. Even though many factors are predictable and are quantified and analyzed for planning before beginning the mining process, we are still inevitably faced with uncertainties only resolved after doing the job. Among them is the case we currently have at hand.
Despite the uncertainties, a rough estimate of waste material in the extracted mineral is necessary. According to the articleby Adén Muñoz, mining supervisor of AYMA Mining Solutions, and Benjamín Cebrián, of Blast-Consult, “it is our responsibility to design, control and to measure the dilution that results in what we do and how we operate”. In other words, the dilution present in minerals is a determining factor for mining operations and extracting processes.
On the other hand, there are various types of dilution that require different design and control processes. According to the abovementioned article, geological dilution“is produced by inaccuracies in the delineation stages of the resource model –waste contact– mineral, mineral transitions, etc. Geological dilution could comprise up to a third of total dilution”. Internal dilution“cannot be separated due to its size and can occur in situations where the mining method dictates a minimum width of extraction –in this sense, internal dilution can be planned; either in relation to the size of the block of the model –internal dilution to the block”. Lastly, external dilution “is unplanned and refers to waste material outside the mineral that is mined with the mining block. External dilution can be caused by production errors or from the falling of materials due to planar instabilities or contamination from backfill”.
Dilution, however, beyond the three general categories, is subdivided in more variants that depend on factors like the type of mineral, whether the mine is underground or open-pit, etc., all of which need different measuring, planning and calculating according to the elements that intervene. Apart from the inherent dynamism of dilution, the people in the team, their experience and extraction processes make it possible for each case to have its own equation. One-of-a-kind. Like that small percentage of difference in DNA that makes each person unique.