Load-haul-dump machines (LHDs) are typically used in underground metal mining opera-tions. Delays or inappropriate use of LHDs can result in production loss. Optimized LHD use is especially crucial in larger mines because longer travel distances increase heat, dust, and gas emissions, which in turn increase ventilation costs. This study, conducted at an existing Swedish sublevel cave underground mine, used discrete event simulation and the AutoMod™ DES tool to determine the ventilation costs related to using too many diesel LHDs in a production area with reduced ore pass availability. When fewer ore passes are available, ventilation costs related to operating LHDs in the production area were found to increase by as much as 200, 224, and 306% for one, three, and six LHDs in operation, respectively.  

Blasting is widely applied in deep rock excavation. The effect of in-situ stresses on the fracturing of rock due to blasting was investigated. A theoretical model was used to explain the effect mechanism of in-situ stresses on crack propagation due to blasting. Four cases with different in-situ stress conditions were numerically investigated. The numerical results indicate that the crack propagation is governed by the blast load in the vicinity of the blasthole while the high in-situ stresses can influence the crack propagation in the far-field. The crack propagation trends towards the direction in which the high initial pressure is applied.

Orepass failure is a well-known problem in deep mines, and the risk of losing an orepass is associated with severe production disturbances. In the near future, one possible scenario in the Loussavaara Kiirunavaara Aktiebolag (LKAB) Malmberget mine is to concentrate the mining operation in fewer, but larger, production areas. In this paper we evaluate the effects of orepass loss on loading, hauling, and dumping operations and production rates using discrete event simulation, by simulating part of the Malmberget mine loading and hauling system under different environmental and operational constraints.

Advanced planning and automation are increasingly important in modern mines. Sophisticated methods for long-term mine planning are often used, and the advent of autonomous machines makes the actual operation more predictable. However, the interface between these two timescales, i.e. the scheduling of the mobile production fleet, often limits the ability to operate mines at maximum profitability. We show how scheduling the production fleet in an underground mine can be modelled as a flow shop. A flow shop is a general abstract process formulation that captures the key properties of a scheduling problem without going into specific details. Thus, the flow shop enables mine scheduling to reap the benefits of scheduling research from other industries. We review recent results from the mining community and the flow shop community, and introduce scheduling methods used in these two fields. This work aims at providing value to researchers from the mining community who want to leverage their skill set, as well as to theoretical researchers by presenting the mining process as a potential application area. Lastly, we discuss the results, and outline some future challenges and opportunities facing the industry.

This paper challenges the traditional notion that mine planners need to plan production so as to incur the lowest mining cost. For a given mine configuration, a mine that increases its mining rate will incur increased mining costs. In an environment in which operations are fixated on cost reduction, a proposal that increases costs will not be readily accepted. Such a proposal requires financial justification-the increase in costs might be recuperated by the additional production. This paper evaluates the net present value (NPV) across a range of copper prices for two underground orebodies located at different depths, using a production rate of 300 kt per quarter and a scenario that introduces additional equipment and costs for 450 kt per quarter. The evaluation was based on the changes of NPV for the orebody located at a shallow depth compared with the orebody at a greater depth. Discrete event simulation combined with mixed integer programming was used for analysis. Unlike traditional sensitivity analysis, this study re-optimizes the mine plan for each commodity price at each production rate. The results show that, for the low mining rate at the final copper price, an NPV of A$ 1530.64 million is achieved, whereas an NPV of A$ 1537.59 million is achieved at a higher mining rate. Even though pushing mining rates beyond traditional limits may increase mining costs, this option may be beneficial at certain commodity prices, particularly when prices are elevated.

As the near surface deposits are being mined out, underground mines will increasingly operate at greater depths. This will increase the challenges related to transporting materials from deeper levels to the surface. For many years, the ore and waste transportation from most deep underground mines has depended on some or all of the following: truck haulage, conveyor belts, shafts, rails, and ore pass systems. In sub-level caving, and where ore passes are used, trains operating on the main lower level transport the ore from ore passes to a crusher, for subsequent hoisting to the surface through the shaft system. In many mines, the use of the ore pass system has led to several problems related to the ore pass availability, causing production disturbances and incurred cost and time for ore pass rehabilitation. These production disturbances have an impact on the mining activities since they increase the operational costs, and lower the mine throughput. A continued dependency on rock mass transportation using ore passes will generate high capital costs for various supporting structures such as rail tracks, shaft extensions, and crushers for every new main level. This study was conducted at an existing underground mine and analyzed the transport of ore from loading areas at the lower levels up to the existing shaft points using trucks without employing ore passes. The results show that, when the costs of extending ore passes to lower levels become too great or ore passes cannot be used for production, haul trucks can be a feasible alternative method for transport of ore and waste up the ramp to the existing crusher located at the previous main level. The use of trucks will avoid installing infrastructure at the next main level and extending the ore passes to lower levels, hence reducing costs.

This paper challenges the traditional notion that mine planners need to plan production at mining rates that result in a low mining cost. For a given mine configuration, a mine that considers increases to its mining rate most often increases mining costs. In an environment in which operations are fixated on cost reduction, a proposal to increase costs may be very difficult to implement. Such a proposal may need to be justified financially because the increase in costs might not be recuperated by the extra production gained. This paper evaluates the net present value (NPV) of the selected range of copper prices for two underground orebodies located at different depths using a production rate of 300,000 tonnes and one that introduces additional costs at 450,000 tonnes per quarter. Discrete event simulation combined with mixed integer programming was used for the analysis. The results shows that, for the low mining rate at the final copper price, an NPV of $755.65M is achieved, whereas an NPV of $773.45M is achieved at a high mining rate. Therefore, even though pushing mining rates beyond traditional limits increases mining costs, pursuing this option at certain commodity prices may be beneficial, particularly when prices are elevated.

One of the challenges that underground mines face today is the deepening of the mines. This, together with lower grades of the deposits, makes the mines strive for higher productivity and lower costs. By introducing autonomous vehicles, the operators will be removed from the face, and thus safety for operators will be improved. Since autonomous vehicles are scheduled to operate during breaks, there is a potential for a productivity increase. The goal with this study was to determine if and to which degree autonomous bolt rigs and scaling rigs can improve the productivity in a deep underground mine.The research is based on data collected during 2013 from New Boliden AB’s Kristineberg mine in Sweden. A simulation tool, SimMine, was used for analyzing the effects of operational changes and for simulation of parameters that are difficult to estimate, such as traffic congestions. A number of scenarios were simulated and compared to the base case with focus on productivity.It can be concluded that the simulation scenarios using faster, manually operated vehicles shows a productivity increase, and that the automated vehicles further improved the productivity increase. The largest productivity increase comes however from faster vehicles, and not from the automation itself.

Mining of ore bodies that are located at great depths enforces long distances to move the excavated rock masses to the surface. The excavated rock mass contains not only ore that can be economically extracted from the face but also waste, which is usually discarded several steps further downstream in the process. As a result large amount of rock masses are transported to the surface, influencing the costs at which the ore is produced. Reducing the amount of waste being transported to the surface by introducing near to face sorting plant would improve the in many cases strained transport system in the deep mine. In this study, one of Boliden’s cut and fill mines was analysed with respect to the challenges related to mass movement and increasing mining depth. The study aims to evaluate the use of the new near to face sorting system in the operating underground mine. Discrete event simulation was used to study and analyse the mass movement with and without the near to face sorting plant. The paper shows how the underground mass movement system and the production were influenced when a near to face sorting equipment was added into the current system.

In today’s underground mass mining the ore pass is an important part of the infrastructure, since it connects two or more of the mine levels and used for conveying or storing large amounts of material. One of the main risks related to an ore pass is when operational or structural failure occurs thus leading to long-term loss of functionality. Developing or rehabilitating an ore pass when major failure has occurred is a time-consuming and expensive operation, and the risk of a long-term ore pass loss motivates the development of alternative transportation strategies in order to ensure the continuation of smooth operations in large underground systems. The study presented in this paper has been done at the Loussavaara Kiirunavaara AB (LKAB) Malmberget mine in Sweden, where the iron ore deposits are being extracted using sublevel caving. The study analyses the transportation system in one of the mine’s ore bodies using discrete event simulation (DES) with a focus on maintaining ore transportation in the event of the loss of an ore pass.