Ore passes play a vital role in underground mining operations by facilitating the gravity-driven movement of ore from production levels to lower levels. Failure of the ore pass has serious consequences, including possible production disruptions and substantial financial investments in reconstruction or rehabilitation. Failure mechanisms are often associated with rock mass quality, stress conditions, and wear of the ore pass walls. This study investigated the degradation of ore pass walls using scanning data at LKAB’s Kiirunavaara mine in Sweden. Geotechnical information obtained from various sources aided in further understanding the ore passes’ conditions. The study revealed variations in the ore pass growth rates, highlighting potential stability concerns and the correlation between throughput and pass growth. The findings underscore the need for continuous monitoring and regular inspection to manage wall degradation. The paper proposes potential rehabilitation measures to ensure the stability and safety of ore passes in mining operations.

Ore passes are often the main part of sublevel caving transportation systems, and they use gravity to move material to lower levels in the mine. During operations, the ore pass structures are exposed to the risk of stoppage and failure, leading to a long-term reduction in operational capacity and affecting productivity. The failed ore passes can be restored or rehabilitated, but the rehabilitation cost is normally high and the time to restore is usually long. To minimize disturbances and stoppage of the ore pass, alternative strategies should be considered. The appropriate design and operation of an ore pass is crucial. Therefore, this study compared running ore pass systems in a filled, near-empty, or flow-through manner using discrete event simulation. The aim was to compare the ore pass operational performance and impact on reaching the daily and 90-day production targets of 76.4 Ktonnes and 6.9 Mtonnes, respectively. The results showed that running the ore pass in flow-through mode, filled manner, and near-empty manner achieved 96%, 80%, and 81% of the production target, respectively. In mining operations where ore pass systems are used to transfer material, running them in a flow-through mode can ensure higher production and fewer hang-ups, as it lessens the chance of blocks arching over a chute throat and leads to less blasting.

In underground mining environment where the loss of orepasses is a dominant factor, the mine may face a challenge of improving the loading and hauling operations. Some of the options will be to rehabilitate the lost orepasses, or developing the new ones. When the rehabilitation cost is high, alternative strategies should be applied to compensate for the orepasses failure. One of the possible options is to use diesel or electric Load-Haul-Dumps (LHDs). The use of diesel-powered LHDs will increase heat and gas emissions which increase environmental concerns and ventilation costs, while adoption of electric-powered vehicles needs to be analysed. Therefore, this study was conducted at an existing underground mine in Sweden, to determine the electricity consumption and costs of electric-powered LHDs when there is a loss of orepasses. The AutoModTM discrete event simulation tool was used during the analysis. The results show that, electric-powered LHDs have significant cost saving when used in case of orepass loss to move materials compared to diesel-powered units. However, the source of electricity to fully adopt electric-powered units may need further financial justifications to evaluate the impacts to the environment.

Today's mining operations require fast reporting and rapid rescheduling based on updated information. An automatic mine scheduling system could not only quickly reschedule but also propose alternative solutions. To avoid the financial and physical risks associated with testing such a system directly in operation, it could be first evaluated via discrete event simulation models. This would offer a safe environment to evaluate different operating rules and algorithms. In this study, this is achieved by integrating automatic scheduling software with a discrete event simulation model.

The research presented in this thesis addresses several aspects of loading operations inunderground mines, in particular tools and equipment selection. It also addresses the flexibilityof the fleet when subject to substantial disturbances, such as ore pass loss, and proposes integration of the scheduling system with discrete event simulation. The thesis begins with a study of discrete event simulation (DES) tools for loading operations in an underground mining system. The results show the benefits of using simulation but also the drawbacks.The thesis presents an analysis of energy consumption and exhaust gas emissions from diesel and electric LHDs. The results show the potential energy savings with the use of electric LHDs. Next, it focuses on the LHD operations affected by long-term ore pass loss (unavailability). It shows the effects on the production system (the ventilation requirements, production and waiting times when too many LHDs operate in the area affected by an ore pass loss) and highlights the need for a flexible solution and a mitigation strategy. Finally, the thesis studies the integration of ABB’s Ability Operations Management System (OMS) with the SimMine simulation model and how this affects LHD operations. The results show the benefits of using the joined platformas a testbed and decision support system.

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.  

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.

The research presented in this thesis addresses a number of challenges related to rock mass transportation in deep underground mines. In particular, high energy consumption and high exhaust gas emissions from diesel and electric LHDs, the effects of ore pass loss on the loading, hauling and dumping operations due to increasing stresses and increasing costs due to the longer vertical transportation of the rock masses. These critical challenges have been identified by a literature review and analysis of data collected from 15 international deep mines. In order to answer the formulated research questions, three studies on various issues related to rock mass transportation in deep underground mines were made, and the analysis was performed mainly using discrete event simulation.

The thesis presents a study of energy consumption and exhaust gas emissions from diesel and electric LHDs with similar bucket sizes. The results show the possible energy savings and a decrease in CO2 emissions when using electric LHDs instead of diesel ones. The thesis also presents a study of the effects of ore pass loss on LHD operations and on the mine production. Maintaining the production with a lower number of operational ore pass structures by increasing the number of LHDs can have a negative effect on the production. This is because an increased number of LHDs in operation will results in increased waiting times for the LHDs and cause variations in the production rate. These variations can be large, causing severe consequences if not managed correctly. The results also show the importance of developing alternative plans for underground loading and hauling operations in case of an ore pass loss. Transportation of rock, especially when mining depth increases, is often associated with high costs and long transportation times. To decrease the amount of unnecessary rock transportation, near-to-face sorting plants may be one alternative. In the thesis, a study was performed on a possible reduction in rock mass transportation to the surface when using this technique. The results conclude that near-to-face sorting plants could lower the environmental effects generated by unnecessary rock transportation to the surface.

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.

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.

This report is part of the work done by Luleå University of Technology within the EU 7th framework project I2Mine, Innovative Technologies and Concepts for the Sustainable and Intelligent Deep Mine of the Future. The work is performed within work package 2 Novel mining and underground processing methods, subtask 2.1.1 Novel mining methods and processes for deep, steeply dipping orebodies.

In an environment of rising energy prices and mining at greater depths, cost-efficient loading and hauling equipment is essential. Conducted at an underground mining operation, this study analyzes the energy consumption and gas emissions of diesel and electric load-haul-dump machines (LHDs) with similar bucket capacities. Based on energy prices from the first quarter of 2014, results of discrete event simulation show that energy costs for diesel and electric LHDs are US$0.24/t and US$0.07/t, respectively. Also, diesel LHDs emit 2.68 kg CO2 per litre of diesel fuel, whereas using electric machines reduces the need for ventilation to mitigate engine heat and emissions and reduces energy costs.

This report is part of the work done by Luleå University of Technology within the EU 7th framework project I2Mine, Innovative Technologies and Concepts for the Sustainable and Intelligent Deep Mine of the Future. The work is performed within work package 2 Novel mining and underground processing methods, subtask 2.1.1 Novel mining methods and processes for deep, steeply dipping orebodies.

This report is part of the work done by Luleå University of Technology within the EU 7th framework project I2Mine, Innovative Technologies and Concepts for the Sustainable and Intelligent Deep Mine of the Future. The work is performed within work package 2 Novel mining and underground processing methods, subtask 2.1.1 Novel mining methods and processes for deep, steeply dipping orebodies. Reaching the ore bodies that are located at greater depths require extensive transportation systems. The transported ore before being refined contains not only minerals that can be economically extracted from the production face but also waste. To reduce the amount of transporting unnecessary material up to the surface near to face sorting plant has been introduced. In this study near to face sorting plant was integrated in the simulation model that was based on one of the Boliden’s cut and fill mines for possible enhancement of the currentand future transportation systems to reduce the unnecessary amount of mass movement upstream. In this study discrete event simulation was used to study and analyse the mass movement before and after near to face sorter implementation. The paper shows the effects on the production rate and distribution of rock mass in the underground mine. When miningoperations will continue to reach greater depths, utilizing sorting technique would be advantageous, as it enables to leave the waste behind, hence reduces the costs necessary for transporting and processing unnecessary material further upstream. Taking into consideration the sorting plant speeds equal to or higher than 70 tph, the sorting plant was able to maintain the speed of the simulated production. If the sorting plant will maintain the speed at 30 tph during the simulation it was not possible to fulfil the yearly production blasting plan. In cases of necessary stockpiling of the material in front of the sorting plant, some of the material would have to bypass the sorting plant and be transported up via hoisting system with the rest of the ore. However, further studies with regards to the feasibility of the pre-concentration and integration issues should be addressed.

SURPAC can be used to plan and design new or already existing mines based on geological data and cost (if using WHITTLE mdoule). Based on the information stored in SURPAC production scheduling, or performing the optimization analysis is possible. It is also possible to store and analyze a large amount of data. Additional advantage is draping of the hard copy existing maps into the software cutting down the time of drawing the mine layout by hand.

Mine development is often a bottleneck in mining operations and is strongly influenced by the choice of excavation method. In this paper, the two well-recognized methods, conventional drill and blast and mechanical excavation, are compared and discussed. The former method is the continuation of a long tradition in mining, while the latter method started to be used in 1960s, when mechanical excavators such as roadheaders, continuous miners or tunnel boring machines were developed. The rate at which the tunnel advances is one of the most important factors for mine development. By evaluating and selecting the right technique, the speed and effectiveness of the development could be improved. This paper aims to estimate and compare the advancement rate between the mechanical excavator and drill and blast method using simulation with AutoMod. This study has been done for one of Boliden Mineral AB’s mines in Sweden. For the drill and blast method, the study shows increased performance for two simultaneously drilled tunnels when compared with a single one. Furthermore, the simulation runs have estimated the total tunnel development times for the specified development lengths. The study is concluded by sketching an interesting picture of mine development using the mechanical excavator.