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  • 1.
    Beyglou, Ali
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Schunnesson, Håkan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Target fragmentation for efficient loading and crushing: The Aitik case2017In: The Southern African Journal of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 1543-9518, Vol. 117, no 11, p. 1053-1062Article in journal (Refereed)
    Abstract [en]

    Blast-induced fragmentation has a significant influence on the operational efficiency of open pit mines, especially on loading and crushing, the two immediate tasks after blasting. This study presents an empirical method to determine the target fragmentation for efficient loading and crushing at the Aitik mine in Sweden. In the study, the loading efficiency of rope shovels was correlated to the energy consumption and throughput of a gyratory crusher. Two photographic techniques were utilized to assess the feed fragmentation, considering the lithological origin of the ore as an indicator of hardness. The results indicate ore hardness is most influential in mid-range fragmentation, with a marginal effect in coarser fragmentations. The influence of fragmentation is more pronounced in the coarse region, with a sudden reduction in efficiency for P80 values coarser than 800 mm. The results suggest tailoring the fragmentation to a P80 of 600-800 mm could lead to higher operational efficiency at Aitik. 

  • 2.
    Gustafson, Anna
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Schunnesson, Håkan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Timusk, Markus A.
    Division of Engineering, Laurentian University, Sudbury.
    Hauta, Rebecca
    Division of Engineering, Laurentian University, Sudbury.
    Productivity of rock reinforcement: Methodology development2016In: The Southern African Journal of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 1543-9518, Vol. 116, no 12, p. 1127-1134Article in journal (Refereed)
    Abstract [en]

    The working environment for ground support installation in mines has improved during the last 20-30 years, with more mechanized equipment for installation of ground support elements such as bolts, cable bolts, and screens. Ground support installation productivity has, however, not followed the same development curve, remaining more or less constant. In some cases, for example the mechanized installation of bolts, productivity has even dropped. One reason for this is that modern mechanized bolt rigs are complex. In this paper we evaluate manual and mechanized ground support systems, propose a way to measure the productivity of bolt rigs, and make relevant comparisons between different mines and equipment. Some productivity measures for rock reinforcement are suggested, using productivity results from eight case study mines

  • 3.
    Salama, Abubakary
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nehring, Micah
    University of Queensland, School of Mechanics & Mineral Engnineering.
    Greberg, Jenny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Financial analysis of the impact of increasing mining rate in underground mining, using simulation and mixed integer programming2017In: The Southern African Journal of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 1543-9518, Vol. 117, no 4, p. 365-372Article in journal (Refereed)
    Abstract [en]

    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.

  • 4.
    Shekhar, Gurmeet
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Gustafson, Anna
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Boeg-Jensen, Patricia
    Luossave-Kiirunavaara AB, Kiruna, Sweden.
    Malmgren, Lars
    Luossave-Kiirunavaara AB, Kiruna, Sweden.
    Schunnesson, Håkan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Draw control strategies in sublevel caving mines: A baseline mapping of LKAB's Malmberget and Kiirunavaara mines2018In: The Southern African Journal of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 1543-9518, Vol. 118, no 7, p. 723-733Article in journal (Refereed)
    Abstract [en]

    The Malmberget and Kiirunavaara mines are the two largest underground iron ore operations in the world. Luossavaara-Kiirunavaara AB (LKAB) uses sublevel caving (SLC) to operate the mines while maintaining a high level of productivity and safety. The paper enumerates the loading criteria and loading constraints at the mines and outlines details of mine design, layout, and geology affecting the draw control. A study of the various draw control strategies used in sublevel caving operations globally has also been done to establish the present state-of-the-art. An analysis of the draw control and loading operations at the Malmberget and Kiirunavaara mines is summarized using information collected through interviews, internal documents, meetings, and manuals. An optimized draw control strategy is vital for improving ore recovery and reducing dilution in SLC. Based on the literature review and baseline mapping study, a set of guidelines for designing a new draw control strategy is presented. The draw control strategy at Malmberget and Kiirunavaara is guided by a bucket-weightbased drawpoint monitoring system that is part of the overall framework. Both mines employ a draw control strategy that considers the production requirements and mining constraints while regulating the loading process through an empirical method based on bucket weights and grades. However, in the present scenario of fluctuating metal prices and increasing operational costs a new draw control strategy is needed which is probabilistic in nature and can handle the uncertainties associated with caving operations.

  • 5.
    Skawina, Bartlomiej
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Greberg, Jenny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Salama, Abubakary
    Gustafson, Anna
    The effects of ore pass loss on loading, hauling and dumping operations and produciton rates in a sublevel caving mineIn: The Southern African Journal of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 1543-9518Article in journal (Refereed)
  • 6.
    Skawina, Bartlomiej
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Salama, Abubakary
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Svanberg, Jenny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Gustafson, Anna
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    The effects of orepass loss on loading, hauling, and dumping operations and production rates in a sublevel caving mine2018In: The Southern African Journal of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 1543-9518, Vol. 118, no 4, p. 409-418Article in journal (Refereed)
    Abstract [en]

    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.

  • 7.
    Svartsjaern, Mikael
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Eitzenberger, Andreas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Determination of magnitude completeness from convex Gutenberg-Richter graphs in the central portion ofthe Kiirunavaara mine2017In: The Southern African Journal of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 1543-9518, Vol. 117, no 6, p. 545-560Article in journal (Refereed)
    Abstract [en]

    This paper describes a study of seismic records from the Kiirunavaaramine footwall which were interpreted in relation with numerical modelsdeveloped outside the study. Seismic data was retrieved from a portion ofthe mine and filtered with respect to the ratio between energy carried byan event's P (primary) and S (secondary) waves (Es/Ep ratio), localmagnitude, and active mining depth. The data was analysed using Es/Epratios and Gutenberg-Richter graphs to determine the event origin,mechanisms, and minimum magnitude cut-off. The magnitudecompleteness was identified by studying the b-value stability and b-valuedifferentiation between origin sets. It was shown that, by separatingseismic events into the origin components shear, complex, and tensilebased on Es/Ep ratios, a representative value for the magnitudecompleteness can be identified for a catalogue with a convex cumulativelog curve. The majority of the events were shown to be of shear-slip originbased on the recorded Es/Ep ratios, with pure tensile events constitutingonly about 10% of the recorded data. Spatial and temporal event locationpatterns were studied and compared with numerical modelling results. Thecomparison showed a correlation between shear-slip seismic events andvolumes experiencing high differential stresses in the lower part of thefootwall. In the upper part of the footwall the results did not reveal anyclear correlation between observed damage in drifts and seismic eventlocations. The concentration of seismic events in the lower portion of thefootwall is discussed in the context of rock mass displacements. Theresults indicate a possible connection between mine seismicity at depthand damage observations in the drifts in higher non-seismic areas byseismic softening and subsequent lateral expansion of the rock mass.

  • 8.
    Umar, Sraj Banda
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Sjöberg, Jonny
    Itasca Consultants AB, Luleå.
    Savilahti, Thomas
    Loussavaara-Kiirunavaara AB (LKAB) Malmberget Mine, Gällivare.
    Modelling of caving and deformation mechanisms of the hangingwall of the Printzsköld oreboby at Malmberget mine2017In: The Southern African Journal of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 1543-9518, Vol. 117, no 4, p. 351-360Article in journal (Refereed)
    Abstract [en]

    Sublevel caving in Malmberget mine results in mining-induced surfacedeformation. One of the currently mined orebodies is the Printzsköldorebody. As mining deepens there is need to assess the behaviour of thecave formed in the subsurface above this orebody. Numerical analysis wasused to assess the effects of extraction to deeper levels and performstrength parametric studies. Stress redistribution was studied, and theresults showed high stress buildups in the hangingwall and the crownpillar. Two failure mechanisms have been identified – shear and tensile.Reducing cohesion by 50% increased the area of the yielded zone by morethan 100% in the hangingwall.

  • 9.
    Zhang, Ping
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Swan, Graham
    Rock Mechanics and Mine Design, Canada.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    1D numerical simulation of velocity amplification of P-waves travelling through fractured rock near a free surface2015In: The Southern African Journal of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 1543-9518, Vol. 115, no 11, p. 1121-1126Article in journal (Refereed)
    Abstract [en]

    The most widely used support design damage criterion for rockburst-prone mines is based upon kinetic energy, which is proportional to the square of the ejection velocity and is commonly expressed in terms of peak particle velocity (PPV). Field monitoring and back-analyses have shown that ejection velocities of the order of 10 m/s and higher can result from seismic events of moderate magnitude. Such velocities are much higher than those predicted using PPV obtained from scaling laws. It has also been found that the peak ground motion (i.e. PPV) on the surface of an excavation is preferentially amplified (by four-to tenfold) compared to the motion in solid rock at a similar distance from the source. However, the wave propagation and interaction processes involved within the fractured rock in generating high ground motion are very complex and are not well understood at this time. In this paper, velocity amplification was investigated by modelling the dynamic interaction between fractured rock and a free surface using a 2D discontinuum-based numerical program, UDEC (Universal Distinct Element Code). A 1D model with a fractured zone was used to represent the fractured rock. Velocity amplification, quantified by PPV, predicted at the free end of the model was 2.0-3.6 times higher than the input velocity. It was found that the wave frequency, fracture stiffness, fracture spacing, and thickness of fractured zone are the main factors that affect the velocity amplification. The results have proved that the interaction of the seismic wave and multiple fractures near the free surface strongly influences the ground motion

1 - 9 of 9
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