ratio of the highest-value metal, Cu, defines the cut-off grade. Based on the points mentioned above, the following cut-off grade calculation structure is detailed in the table below: Table 5 - Total Ore Sorting Process Cost by Material Material Mass Pull (%) Rehandling Cost ($/t) OS Plant Cost ($/t) Processing Cost ($/t) G&A Cost ($/t) Total Cost ($/t) Product 40.80 3.97 3.02 3.3 1.5 11.7 Reject 59.20 3.97 3.02 - - 7.0 Table 6 – Calculation of cut off sorting Total Cost ($/t) Cut Off Cu-eq (%) Upgrade Cu (%) Ore Sorting Cut Off ($/t) 21.9 0.25 1.71 10.5 5.5 Material Classification According to NSR Knowing the cut-off grade of the ore sorting process, it is necessary to compare it with the operational cut-off grade, which is defined according to the Net Smelter Return, NSR, expressed in $/t. Classification is carried out by ranges: ore with NSR greater than 17.5 $/t is sent directly to the plant, LOM reserve ore, ore between 10.5 $/t and 17.5 $/t is sent to the ore sorting plant, and ore with NSR lower than 10.5 $/t is considered waste and sent to the waste dump, as shown in the following table. Table 7 - Destination by NSR Range NSR Range ($/t) Material Type Destination > 17.5 LOM Reserve Direct Feed > 10.5 Ore Sorting Reserve Ore Sorting Plant < 10.5 Waste Waste Dump 5.6 Impact on Reserve Calculation Before quantifying the additional tonne in reserves generated by implementing the sorting process, it is essential to determine the initial tonne of the base plan. A minimum cut-off grade of 10.5 $/t is established to differentiate between ore and waste. Based on this cut-off and through the construction of the average grade–tonne curve using data from the reserve model, it is possible to accurately quantify the tonne corresponding to the base plan.
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