IMPROVING MINE–PLANT RECONCILIATION THROUGH ONLINE GRADE MEASUREMENT ON THE CONVEYOR BELT: A CASE STUDY FROM CHUQUICAMATA UNDERGROUND *P.S. Peñaloza1, C.A. Córdova2 ¹Production Management Superintendence, Mineral Resources and Development Department, Chuquicamata Division, Codelco, Chile, ppena018@codelco.cl 2Production Management Superintendence, Mineral Resources and Development Department, Chuquicamata Division, Codelco, Chile, ccord004@codelco.cl ABSTRACT Chuquicamata Division faces the challenge of improving mine–plant reconciliation in a context of multi-source ore processing and transition to underground mining. Currently, feed grade estimation relies on discrete sampling, which, together with time delays and blending effects, results in discrepancies on the order of 0.01% to 0.02% CuT between mine-reported grades and those reconciled in the metallurgical balance, with significant economic impact. In valuation terms, a deviation of 0.01% CuT is estimated to represent approximately USD 1.4 million per 1.7 Mt processed, considering a 90% recovery and a copper price of around USD 4.0/lb. This work presents the technical and economic evaluation of a solution based on the implementation of an online grade analyzer on the Overland conveyor at Chuquicamata Underground, aimed at reducing this gap. The evaluation considers the capability for continuous, real-time measurement of elements such as Cu, Mo, Fe, and As, as well as its integration into operational control systems. The methodology includes initial calibration using representative ore samples, validation under controlled conditions, and comparison with laboratory assays and metallurgical balance data. Based on the results obtained, which demonstrate the potential of online measurement to reduce the mine–plant gap and its associated economic impact, it has been decided to proceed with the system implementation during the present year. The project is currently in the permitting and calibration phase. The results of this evaluation highlight the potential of online measurement to improve ore traceability, reduce uncertainty in grade estimation, and enable more timely and data-driven operational decisionmaking. KEYWORDS Mine–plant reconciliation, underground mining, online analyzer, elemental grades
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