A Novel Approach to Estimate the Gap Between the Middle- and Short-Term Plans

摘要

In almost all copper mining companies, mine planning is done considering different time frames,rnleading to long-term (life-of-mine) (LOM), medium-term (fi rst three years) and short-term (fi rstrnyear, monthly, weekly, and up to daily plans). Shorter term plans are usually associated with morernabundant information, hence models with lower uncertainty. However, they capture more of thernvariability found on the geological attributes. In long-term models, usually estimation methods tendrnto hide this variability, providing smoothed interpretations.rnMedium and long-term plans consider average values for the parameters and optimisationrntechniques are applied aimed at maximising the economic profi t. Short-term plans, on the otherrnhand, are made to comply with the medium-term promises, maximising the use of the availablernresources (equipment and processing capacities) and dealing with the variability not characterisedrnin the previous planning stages. This generates an important gap between the short-term and thernmedium and long-term plans.rnA case study was made using an important oxide copper mine, where the variability found in thernshort-term plan has a large impact in the productive process, thus reducing the daily ore gradernvariability is an important goal. In this paper, this planning issue is addressed by creating mediumtermrnmine plans using mixed integer programming which are compared using the output of arnsimulation of the daily extraction that is aimed at satisfying the daily constraints of the processingrnplant, the availability of mining equipment and the variability of ore grade. The result shows thernexpected gap between these mine planning processes, which suggests correcting some of thernparameters used in future medium and long-term plans.