Multi-stage dumping sequence - a feasible waste management alternative for open pit mining

Abstract

Waste management and environmental aspects are progressively gathering attention in the mining industry. Mine planners must deal with increasingly complex tasks to balance between ore block schedules, waste disposal, operational cost and environmental reclamation. The mine incomes are generally related to mining and processing of the ore, thus most optimization researches regarding strategic mining usually focus mainly on ore extraction. Nevertheless, waste sequencing and disposal play an important role given that, in several situations in open pit mining, waste volumes are generally larger than ore volumes and must be moved to reach the buried and deeper ore bodies. In some cases, a significant percentage of operational costs is represented by waste haulage and disposal. Thus a careful planning strategy must be considered to minimize unnecessary expenses. Selecting locations for waste dumps is also a challenge. Many operational and technical aspects must be considered, not to mention the increasingly limiting environmental constraints. This definition can be very time consuming, and if it is not properly studied, may negatively impact the mine operation during its lifetime. This article investigates a new approach for mine waste management called the multi-stage dumping sequence (MSDS), suggesting the use of temporary waste dumps along the way to the final dump destination. Although this method requires material re-handling, which is considered a paradigm in mine industry, it certainly provides additional time to design and permit the final waste dump site and, if well planned, might even result in profit increases by reducing haulage distances in the first years of operation.

Establishing the quantitative and qualitative limits of the applicability of the multi-stage dumping sequence in open pit mining

“…Each time a block is hauled, the cost is applied; thus re-handling operations represent an extra cost. Differently from previous work (Kuckartz and Peroni 2019;Kuckartz et al 2021Kuckartz et al , 2022, this case study does not consider equipment acquisition (such as haulage trucks and shovels), given that a contractor is responsible for managing a fleet capable of dealing with the mine schedule within the limits of material movement assumed in this analysis.…”

“…The data regarding waste block schedules, comprising the operational cost, waste dump capacities and haulage distances were compiled in a spreadsheet where the calculation was performed, including NPC at a 10% annual discounted rate. The findings of this study were also integrated with previous results from Kuckartz and Peroni (2019), Kuckartz et al (2021Kuckartz et al ( , 2022 and then synthesised to provide overall guidance for the potential use of the MSDS, listing the main variables and their relationships.…”

“…The MSDS_2 original setting variation also resulted in a more negative NPC, which can be explained by the TWD location. In contrast to previous studies (Kuckartz and Peroni 2019; Kuckartz et al 2021Kuckartz et al , 2022, in which the TWD was placed along the way to the FD, in this study the TWD was placed in an area that is not necessarily on the way to the FD. The previous studies considered the TWD position between the pit exit and the FD, so the total haulage distance for the MSDS variations is very close to the BC.…”

“…Instead of sending the waste to a final dump (FD) in the first years of operation, a temporary waste dump (TWD) is placed as close as possible to the pit, over a planned area of the mine, reducing the haulage distance. Kuckartz et al (2021) implemented an MSDS optimisation algorithm for a phosphate mine case study in a horizontal and tabular orebody. The authors simulated thousands of scenarios, varying the distance from the pit exit to the temporary dump as well as the annual re-handling rate (from the TWD to the FD), resulting in up to a 2.5% NPC reduction compared with the base case (sending waste blocks directly to the FD throughout the mine life).…”

Determination of rational technological schemes for the completion of open-pits taking into account land reclamation

“…This article [17] investigates a new approach for mine waste management called the multi-stage dumping sequence, suggesting the use of temporary waste dumps along the way to the final dump destination. Although this method requires material re-handling, which is considered a paradigm in mine industry, it certainly provides additional time to design and permit the final waste dump site and, if well planned, might even result in profit increases by reducing haulage distances in the first years of operation.…”