# Distribution of Operating Costs Along the Value Chain of an Open-Pit Copper Mine
## 4 Discussion  
This study offers a comprehensive analysis of the distribution of operating costs along the value chain of an open-pit copper mine, with particular emphasis on the contribution of various operational units. Results indicate that mineral processing, particularly comminution, represents the largest share of operating costs, with milling alone accounting for 59.08% of total operating costs. Crushing is the second-largest contributor, representing 10.99% of the overall costs. In essence, comminution (i.e., crushing and milling) accounts for nearly 70% of total OPEX. These findings are consistent with previous studies that have consistently highlighted comminution as one of the most expensive stages in mining operations [3, 50, 56, 57]. This is primarily due to the energy-intensive nature of the process, coupled with its relatively low operational efficiency [58, 59]. In terms of mineral processing operations, comminution constitutes 90.05% of the total mineral processing OPEX (Table 3), substantially exceeding the industry benchmark range of 40-50% [50, 51]. This discrepancy can be attributed to the fact that only comminution and flotation have been considered as mineral processing units in this study, while other key operations, such as dewatering, tailings disposal, and extractive metallurgical processes, were excluded from the analysis [54]. As a result of this, the contribution of comminution to mineral processing OPEX appears disproportionately high, underscoring the energy-intensive nature of milling and crushing operations. The substantial energy demands of comminution emphasize the need to prioritize energy-efficient grinding technologies, including high-efficiency equipment and advanced comminution methods [60, 61, 62]. Also, the integration of renewable energy sources such as solar or wind can further reduce energy consumption while improving operational efficiency and sustainability, ultimately leading to lower overall costs [63, 64, 65, 66, 67]. Looking at flotation, this operation accounts for 7.74% of the total OPEX of the open-pit mine value chain and plays a crucial role in copper recovery. Automating flotation processes and optimizing reagents usage could further enhance recovery rates, improve profitability, and reduce OPEX. This would then contribute to enhancing the overall efficiency of the mine [68]. With flotation representing 9.95% of total processing OPEX, its contribution is deemed low compared to the published industry benchmark range of 15-20% [52, 55]. This may suggest that the flotation process in this case study is more cost-efficient compared to the average value reported in the literature. Drilling and blasting, which contributed 3.35% and 4.21% to the total OPEX, respectively, may seem modest in terms of their individual cost shares. However, they play a critical role in determining the efficiency of all subsequent processes, including loading, hauling, crushing, and milling. The literature suggests that drilling and blasting can account for up to 15% and 10% of total mining costs, respectively [40, 41, 42, 31]. This case study shows that drilling and blasting account for 15.09% and 18.97% of mining OPEX, respectively. The drilling cost is at the higher end of the industry benchmark range of 8-15%, which seems consistent with typical variations in drilling costs, especially in harder rock environments. The higher blasting OPEX of 18.97% is primarily driven by the significant expenses associated with explosives and accessories, making up approximately 97.9% of the total blasting cost. Implementing mine-to-mill optimization strategies, particularly by increasing blasting intensity, may raise blasting costs in the short term. Nevertheless, this can lead to substantial savings downstream through improved ore fragmentation and reduced energy required for the crushing and grinding processes [32]. Other mining operations, such as loading, hauling, stockpiling, and blending, account for 4.88%, 8.99%, 0.19%, and 0.57% of the total OPEX, respectively.