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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: Journal of the Southern African Institute of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 2411-9717, 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.
    Beyglou, Ali
    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.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Face to Surface –Task 1: Baseline Mapping of the Mining Operation in Aitik2015Report (Other academic)
    Abstract [en]

    “Face to Surface” is a project within the strategic innovation program “Mining and Metals”, which is a collaboration between Vinnova, Formas and Energy Agency of Sweden with additional funding from Boliden Mineral AB and LKAB. The project is aimed to improve productivity and efficiency of mining activities through optimization of the overall production chain. The current status report corresponds to the first task of the project–Baseline Mapping.The report presents the overall process chain of mining operation in Boliden Aitik copper mine, Sweden. The production chain is initially described as a system of singular processes. Each process is then described in more details, including inter-relations and downstream effects of each process within the operation. The report provides a basis for identification of potential fields of improvement in the process. The subsequent tasks of the project will be conducted upon internal discussions based on the findings of this report.

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  • 3.
    Beyglou, Ali
    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.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Johansson, Nils
    Boliden Mineral AB.
    Adjusting Initiation Direction to Domains of Rock Mass Discontinuities in Aitik Open Pit Mine2015In: 11th International Symposium on Rock Fragmentation by Blasting: Fragblast11, Carlton, Vic: The Australasian Institute of Mining and Metallurgy, 2015, p. 385-391Conference paper (Refereed)
    Abstract [en]

    As demand for optimisation of mining processes increases, more attention is drawn to blast performance and fragmentation improvement. Fractures and discontinuities are among the most influential factors in blast results, therefore one of the initial steps towards blast optimisation is to gather information about the rock mass and integrate it in blast design. This paper presents a method for assessment of rock mass discontinuities and integrating it in production blasts in the Aitik open pit copper mine in Sweden. 3D photogrammetric techniques were utilised to map discontinuities and distinguish domains of similar geologic structures in the pit. As a pilot study for a future campaign, four different initiation directions were tested through six pilot blasts in one of the domains. The results were compared in terms of swell and loading efficiency of rope shovels to identify the correlation between blast performance and initiation direction compared to major discontinuity families. It was established that in the trial domain, blasts initiated towards north or north-west yielded larger swell and better performance of loading. Comparing these blasts with discontinuity families show that there is a correlation between blast performance and initiation direction according to the dip and strike of these discontinuities. Such knowledge can be used for future blasts in the same domain to increase long-term operational efficiency through slight modifications in drill pattern and initiation design.

  • 4.
    Chen, Ming
    et al.
    State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan, 430072, China; Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering Ministry of Education, Wuhan University, Wuhan, 430072, China.
    Wei, Dong
    State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan, 430072, China; Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering Ministry of Education, Wuhan University, Wuhan, 430072, China.
    Yi, Changping
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. Swedish Blasting Research Centre, Luleå, Sweden.
    Lu, Wenbo
    State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan, 430072, China; Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering Ministry of Education, Wuhan University, Wuhan, 430072, China.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. Swedish Blasting Research Centre, Luleå, Sweden.
    Failure mechanism of rock mass in bench blasting based on structural dynamics2021In: Bulletin of Engineering Geology and the Environment, ISSN 1435-9529, E-ISSN 1435-9537, Vol. 80, no 9, p. 6841-6861Article in journal (Refereed)
    Abstract [en]

    This study establishes a multiple degrees-of-freedom structural dynamics analytical model to analyse the influence mechanism of different factors on blasting tight bottom and shape of muckpile. The structural displacement response and distribution of internal forces in the bench rock mass are analysed based on several factors including blasting parameters, explosion load, initiation condition, and geological condition. In addition, the structural failure characteristics of the bench rock mass are studied based on a rock strength criterion. The results indicate that the explosive load strength determines the internal forces of the bench rock mass. The use of blasting parameters with large borehole spacing and small row spacing can increase the internal force and deformation of the bench rock and enhance the effect of the breaking and throwing of rock mass. In addition, the strengthening of the lithology of the bottom rocks or weakening of the lithology of the middle rocks can make destroying the bottom rock mass more difficult and increase the probability of blasting tight bottom formation. Adjusting the initiation point to below the weak-lithology segment of the bench can enhance the internal force and displacement of the bottom rock mass, to improve the blasting effect and avoid blasting tight bottom formation. Combined with the bench blasting field test of the Changjiu limestone mine, it verifies the results of the theoretical analysis of the bench blasting rock mass destruction based on structural dynamics. The results can be used as the theoretical basis and technical support for improving the bench blasting effect. 

  • 5.
    Danielsson, Markus
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Ghosh, Rajib
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Navarro Miguel, J.
    Universidad Politechnica de Madrid.
    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.
    Utilizing production data to predict operational disturbances in sublevel caving2017In: Mine Planning and Equipment Selection (MPES 2017): Proceeding of the 26th International Symposium on Mine Planning and Equipment Selection Luleå, Sweden, August 29-31, 2017 / [ed] Behzad Ghodrati, Uday Kumar, Håkan Schunnesson, Luleå: Luleå tekniska universitet, 2017, p. 139-144Conference paper (Refereed)
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  • 6.
    Danielsson, Markus
    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.
    The Influence of Blast Fragmentation on Loadability in Sublevel Caving2018In: Proceedings of the Forty-fourth Annual Conference on Explosives and Blasting Technique: January 28-31, 2018, San Antonio, Texas, USA / [ed] Kevin Hachmeister, International Society of Explosives Engineers , 2018Conference paper (Refereed)
    Abstract [en]

    In sublevel caving, blasted material flows gravitationally into the drawpoint from above in a periodical manner. This type of flow behavior entails muck pile conditions that are variable along the course of extraction. The effect of this variability on the LHD (Load-Haul-Dump) operation in terms of loading efficiency and ability to undermine the blasted ring is not fully understood as of today. This paper presents results from a field test in LKABs Malmberget mine in Sweden, where the influence of fragmentation on the loading operation has been studied in detail. Drawpoint filming was conducted for extraction of two rings equivalent of roughly 10000 metric tons (~9842 long tons) of material each. The analysis includes fragmentation measurements, muck pile classification, and general estimations in terms of loadability. Further, an evaluation of LHD machines from two different manufacturers was conducted to identify and highlight differences. The results show that fragmentation, muck pile compactness, and flow characteristics are all interdependent. Flow disturbances and the subsequent loading of compacted fine material in the back of the ring have been identified as the main reason for occurring problems and prolonged digging times. However, the ability to sufficiently undermine the blasted ring has been identified to primarily depend on digging depth which is only observed to be high during flow disturbances. An absence of flow disturbances seem to promote high loading efficiency but simultaneously limit the maximum digging depth. A mid-range particle size distribution with a low amount of fines has proven beneficial for overall loading efficiency. The various LHDs employed showed significant variations in terms of ability to handle difficult loading situations (e.g. compactness, boulders, etc.).

  • 7.
    Greberg, Jenny
    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.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Project: Face to Surface2014Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    Projekt inom ramen för SIO STRIM

  • 8.
    Gustafson, Anna
    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.
    Face to Surface: a fragmentation study2016Report (Refereed)
    Abstract [en]

    As ore grades have decreased and the mining depth has increased over the past few decades, other characteristics than ore grade and tonnage are becoming important. The underground mining process, from in-situ rock mass characteristics to the final mill product with fully liberated minerals, consists of a chain of unit operations that impact, and are influenced by, fragmentation. This report presents the baseline mapping of the project “From Face to Surface”, studying the effects of fragmentation on the process flow in an underground SLC mine. It analyses the underground unit operations in detail, from mine planning to shafts, and maps the blast fragmentation’s effect on the process flow. The goal is to provide a deeper understanding of fragmentation´s effect on different unit operations. The objective is to describe the mining operation at Luossavaara-Kiirunavaara AB (LKAB) and identify key areas for improving fragmentation. To understand how fragmentation influences different operations in the mine, the project conducted a literature study, collected data and interviewed mine personnel in LKAB’s Malmberget mine. Data were collected from the mine’s internal systems, such as GIRON, WOLIS, IP21 and a local drilling data system. The interviews were conducted in cooperation with research personnel from the mine.This baseline mapping shows that the mining operation in Malmberget is affected by fragmentation in several ways. For some unit operations, the fragmentation has a large impact, while for others, it has none at all. The influence of fragmentation starts with the loading operation after the initial blasting and ends with the crushing operation. For the former, boulders are the largest problem, as they cause a great deal of idle time, either when they have to be moved to a separate drift for secondary blasting or when they create hang-ups in the ore passes. When boulders are dumped into the ore passes, they risk damaging the ore pass walls. If boulders create a hang-up, it has to be removed. If the hang-up must be removed with explosives, there is a risk of further damaging the ore pass. In addition, the toxic fumes created by the explosives hinder production until the pass is ventilated. Finally, hang-ups affect the transportation operation as the trucks cannot use an ore pass blocked by a hang-up or closed for ventilation of toxic fumes. There is also a slight possibility that a boulder which does not get stuck in the ore pass will get stuck on a truck. The last operation affected by fragmentation is crushing; boulders and large fragments risk creating a hang-up in the crusher. There are no reports of problems related to fragmentation after this point.The results suggest that further work and mine trials are required in the following areas: drilling, loading, ore passes and crushers.

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  • 9.
    Gustafson, Anna
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Jonsson, Kristina
    LKAB.
    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.
    From Face to Surface: a Fragmentation Study2016In: Seventh International Conference & Exhibition on Mass Mining : (MassMin 2016), Sydney: The Australian Institute of Mining and Metallurgy , 2016, p. 555-562Conference paper (Refereed)
    Abstract [en]

    The underground mining process, from in-situ characteristics of the unmined rock mass to the final mill product with fully liberated minerals, consists of a chain of unit operations. Some of them influence fragmentation while fragmentation impacts others. From a production point of view, fragmentation is a key parameter for the proper functioning of many unit operations and affects total production; it influences the ability to load, haul and crush the rock later in the process. Fragmentation varies because of rock mass strength, the presence of joints, the chosen explosive, specific charge (kg/m3) and quality of drill holes. The efficiency and result of unit operations such as drilling, blasting, loading and crushing depend on the rock properties which vary throughout a mine. Generally speaking, operations are not well adapted to the actual rock properties, leading to a non-optimised flow in production. This paper presents the initial part of a project that will build knowledge on the impact of fragmentation on each step of the production chain in an underground mine. It identifies the key parameters of fragmentation which influence the overall energy consumption and productivity in a mining operation through interviews, mine visits and a literature review. In the subsequent stages of the project, a number of field tests in the case study mine will address important segments of the production process where fragmentation is a major obstacle to improvements. Optimising the entire process, rather than isolated unit operations, will lead to increased productivity, decreased amount of interruptions and lower energy consumption.

     

  • 10.
    Ittner, Henrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. Svensk Kärnbränslehantering AB.
    Olsson, Mats
    EDZ Consulting AB.
    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.
    Multivariate evaluation of blast damage from emulsion explosives in tunnels excavated in crystalline rock2019In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 85, p. 331-339Article in journal (Refereed)
    Abstract [en]

    Blast damage in tunnels is usually regulated in Swedish infrastructure contracts as it can influence the quality and lifecycle cost for tunneling projects. The topic is important for underground constructions with a long operation period such as tunnels for public transport, permanent access tunnels in mines or underground repositories for nuclear waste. This paper aims to evaluate the influence of design and geology variables on the resulting blast fracture length and frequency by means of multivariate data analysis. The analysis was based on data from five field investigations carried out at tunnel sites in Sweden and Finland where emulsion explosives were used. Data was compiled and analyzed using Principal Component Analysis (PCA). Charge concentration was found to be the most influential design variable and hole spacing had limited influence on blast fracturing. Results from the PCA suggest that blast fractures length could be dependent also on geology and natural fractures. Three main groups of fracture patterns were identified, one group with relatively few and short blast fractures, a group with several longer blast fractures and a group with few or a single long blast fracture. The result shows differences in fracture length between the column and bottom charge part of the contour holes, with blast fracture lengths up to approx. 40 cm for the column charge and up to approx. 60 cm for the bottom charge.

  • 11.
    Ittner, Henrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. Swedish Nuclear Fuel and Waste Management Company (SKB).
    Åkeson, Urban
    Swedish Transport Administration (TRV).
    Christiansson, Rolf
    Swedish Nuclear Fuel and Waste Management Company (SKB).
    Olsson, Mats
    EDZ Consulting AB.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Recent Swedish Studies on the Extent of Blast Damage after Excavation2016Conference paper (Refereed)
    Abstract [en]

    This paper presents two recent studies on the extent of blast damage after excavation in crystalline rock. The Swedish Transport Administration and the Swedish Nuclear Fuel and Waste Management Company (SKB) are both under regulations to limit excavation damage during construction of tunnels. SKB is also required to limit the Excavation Damage Zone (EDZ), as this could be a potential flow path for radionuclides in the planned repository for spent nuclear fuel.Presented in this paper are investigations of blast damage from three tunnel sites, a road tunnel, an experimental tunnel in Äspö Hard Rock Laboratory and an underground subway depot.As expected the fractures resulting from the bottom charge are both longer and more frequent then those mapped in the column charge. The results show that the requirement to limit blast damage according to Swedish regulations was fulfilled for the column charge at the three studied sites.

  • 12.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Effects of confinement and initiation delay on fragmentation and waste rock compaction: Results from small scale tests2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Sub-level caving (SLC) is classified as a mass mining method and there is an increasing interest in its application worldwide and in a very wide range of geotechnical environments. Design of sub-level blasting rounds and optimization has become more important now when the sizes of the blasting rings have become larger. Sufficient fragmentation is one of the key factors and in confined blasting, as in sub-level-caving, this influences the mobilization of the blasted ring. The caved rock or debris at the interface first acts as a wave trap i.e. the debris at the SLC interface reduces the fragmentation and the swelling of the blasted ring and it dissipates the explosive energy. These phenomena may immobilize the blasted ring, causing ore losses.Small-scale blasting has been carried out to investigate and clarify this phenomenon. To minimize geometrical and geological effects, tests were made on Ø140 mm cylinders of magnetic mortar, which fractures like magnetite but is a less variable material. The cylinders were placed inside a Ø300 mm steel cylinder and confined by packed aggregate. The explosive source was decoupled PETN cord with different strengths in a center hole, which gave a specific charge between 0.2 and 2.6 kg/m3. The magnetic mortar and the nonmagnetic aggregate allowed for post-blast magnetic separation. The setup provides very repeatable results. The fragmentation of the blasted mortar and the aggregate plus the swelling of the confined mortar cylinders have been measured. As a reference, free mortar cylinders without radial confinement were used. More than 160 tests have been made with the cylindrical set-up.The results show that the confinement results in fragmentation being coarser when compared to that from free cylinders, and that the properties of the debris have a strong influence on the fragmentation and the swelling of the blasted materiel/compaction of the confining material. For the latter, a freezing-slicing method has been developed. The cylinders could thus be sliced perpendicular to the charged hole and then photographed to measure the radial expansion at different heights. The acoustic impedance between blasting material and confining debris has been applied to give a material description in a simple and physical form. This, in combination with the specific charge, has been shown to influence the fragmentation and compaction to a great extent. For the compaction, the porosity of the confining debris is also an influencing factor. Two prediction equations have been presented with high coefficients of determination, both for fragmentation and compaction. The tests have also been shown to be a good input for numerical modelling of blast compaction and reliable input for future numerical modelling of blast fragmentation. Further, a series of detailed small-scale tests have been made to investigate the use of short delays to promote better fragmentation caused by shock wave interactions. The block design had a size of 650/660×205×300 mm (L× W× H) and two rows with five Ø 10 mm blastholes in each row. The spacing and burden were 110 mm and 70 mm respectively, giving an S/B ratio of 1.6. The results showed no distinct differences or high improvements of the fragmentation when the delays were in the time range of interactions compared to no shock wave interactions. The decrease of x50 was around 20 % at a delay time ~1.1 ms/m burden compared with longer delays like 2 ms/m. A statistical analysis of the results has been made to evaluate the minimum at short delays and it is not significant.

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  • 13.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Fragmentation and waste rock compaction in small-scale confined blasting2008Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Sub-level caving (SLC) is an important mass mining method, used at LKAB e.g. The caved rock or debris at the SLC interface reduces the fragmentation and the swelling of the blasted ring and it dissipates the explosive energy. These phenomena may immobilize the blasted ring, causing ore losses. There are two major factors that influence the mobilization of the blasted ring, fragmentation and swelling of the blasted material. The caving process is influenced by also the stiffness of the waste rock, which is dependent in some way by the compaction that the blast ring contributes to. To investigate these phenomena in large-scale is very difficult and nearly impossible due to the mining method itself. Therefore model scale tests have been made to understand the mechanisms of rock breakage and therefore fragmentation under relatively confined conditions. To minimize geometrical and geological effects, tests were conducted on Ø140 mm cylinders of magnetic mortar, which fractures like magnetite but is a less variable material. The cylinders were placed inside an Ø300 mm steel or plastic cylinder and confined by packed aggregate. PETN cord with different strengths in a centred hole gave a specific charge between 02 and 2.6 kg/m3. This thesis describes and discusses how fragmentation and compaction, the reverse of swelling, depend on the specific charge for different types of debris confinement. Four different types of debris have been tested and for one of them a confining pressure of about 0.42 or 0.86 MPa was induced by a slotting and bolting of the steel cylinder. The results show both that the passive confinement makes the fragmentation considerably coarser than from free cylinders and that the properties of the debris have a strong influence on both fragmentation and swelling. The effect of the confining pressure was relatively small however and interpreted mainly by changes in debris porosity. The magnetic mortar and the non-magnetic aggregate allow for post-blast magnetic separation. The setup provides extremely repeatable results. The fragmentation of the blasted mortar and the aggregate plus the compaction (reverse swelling) of the confined mortar cylinders have been measured. Free mortar cylinders were used as a reference To date, more than 160 cylinders have been shot and evaluated in terms of fragmentation or compaction. It has been clearly shown that the test set-up is robust and gives repeatable results. The small scale tests are a first step to increase the understanding of confined blasting as in sub-level caving. By using the acoustic impedance between the blasted material and the confining debris, a relationship for both fragmentation and compaction have been found depending on material, specific charge and physical properties of the debris. Regression analysis has been used for both tasks, where the two statistical hypotheses clearly have good agreement with actual data i.e. the prediction models can forecast both the fragmentation and compaction for this set-up with reasonable accuracy The results can be comparable with confined blasting in large scale, this both that it have representative design parameters that fulfil in many ways the scaling laws and the second is that it can be linked to other comparisons between large-scale and small-scale, where the similarities have been shown. The results from this thesis have shown to be a good input for numerical modelling, where confined blasting is one of the new tasks. This will be a part of the coming work to optimally design SLC-rings for maximum output of ore.

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  • 14.
    Johansson, Daniel
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nyberg, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Stenman, Ulf
    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.
    Shock front curvature measurements of emulsion explosives2019In: Tenth EFEE World Conferenceon Explosives and Blasting / [ed] R Holmberg et al, European Federation of Explosives Engineers , 2019, p. 409-416Conference paper (Refereed)
    Abstract [en]

    This paper will discuss a suggested methodology and data collection carried out within the EU-project SLIM (Sustainable Low Impact solution for exploitation of small Mineral deposits based on advanced rock blasting and environmental technologies). The field work took place during 2017 at a test site near Stockholm, Sweden. This paper suggests a method to measure the detonation front curvature and the velocity of detonation of explosives. The purpose for this is to increase the understanding of the detonation properties of emulsion explosives as used in many blasting operations around the world. In this study, the key parameters of the performance of the emulsion explosive are its non-ideal detonation front curvature and its velocity of detonation (VOD). The charge diameters have been varied Ø25 mm up to Ø65 mm i.e. from nearly critical diameters for a steady detonation up to diameters used in mining/quarrying and tunnelling. The suggested methodology also introduces a heavy and thick-walled mortar as a confiner for the explosive. This to simulate similar conditions as in blasting in rock. Additional to the proposed methodology and set-up, a scheme to analyse and evaluate the measurements is also proposed.

  • 15.
    Johansson, Daniel
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Ouchterlony, Finn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering - Swedish Blasting Research Centre.
    Fragmentation in small-scale confined blasting2011In: International Journal of Mining and Mineral Engineering, ISSN 1754-890X, E-ISSN 1754-8918, Vol. 3, no 1, p. 72-94Article in journal (Refereed)
    Abstract [en]

    Design of sub-level blasting rounds and optimisation has become more important now when the sizes of the blasting rings get larger. Sufficient fragmentation is one of the key factors, and in confined blasting as in sub-level caving, this influences the mobilisation of the blasted ring. Model scale tests have been made to understand the mechanisms of rock breakage and therefore fragmentation under relatively confined conditions. By using the acoustic impedance between the blasted material and the confining debris, a relationship for fragmentation has been found depending on material, specific charge (powder factor) and physical properties of the debris. The results can be comparable with confined blasting in large scale.

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  • 16.
    Johansson, Daniel
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Ouchterlony, Finn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Shock wave interactions in rock blasting: the use of short delays to improve fragmentation in model-scale2013In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 46, no 1, p. 1-18Article in journal (Refereed)
    Abstract [en]

    A series of detailed small-scale tests have been made to investigate the use of short delays to promote better fragmentation caused by shock wave interactions. The block design had a size of 650/660 × 205 × 300 mm (L × W × H) and two rows with five Ø 10-mm blastholes in each row. The spacing (S) and burden (B) were 110 and 70 mm, respectively, giving an S/B ratio of 1.6. The results showed no distinct differences or high improvements of the fragmentation when the delays were in the time range of interactions compared with no shock wave interactions. The decrease of x 50 (mean size) was around 20 % at a delay time ~1.1 ms/m burden compared with longer delays like 2 ms/m. A statistical analysis of the results has been made to evaluate the minimum at short delays and it is not significant

  • 17. Johansson, Daniel
    et al.
    Ouchterlony, Finn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Edin, J.
    Luleå University of Technology.
    Martinsson, L.
    Luleå University of Technology.
    Nyberg, Ulf
    Blasting against confinement, fragmentation and compaction in model scale2008In: MassMin 2008: Proceedings of the 5th International Conference and Exhibition on Mass Mining, Lulea, Sweden 9-11 June 2008 / [ed] Håkan Schunnesson; Erling Nordlund, Luleå: Luleå tekniska universitet, 2008, p. 681-690Conference paper (Refereed)
  • 18.
    Johansson, Daniel
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Ouchterlony, Finn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering - Swedish Blasting Research Centre.
    Nyberg, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering - Swedish Blasting Research Centre.
    Blasting against aggregate confinement, fragmentation and swelling inmodel scale: [Modellförsök med sprängning mot rasmassor: inverkan på styckefall och svällning]2007In: Fourth EFEE World Conference on Explosives and Blasting: [Vienna Conference Proceedings 2007] / [ed] Peter Moser, European Federation of Explosives Engineers , 2007, p. 13-26Conference paper (Refereed)
    Abstract [en]

    Sub-level caving (SLC) is classified as a mass mining method and there is increasing interest in its application world wide and under a very wide range of geotechnical environments. In terms of flow, the caved rock or debris at the interface first acts as a wave trap, which may reduce the fragmentation. Model scale tests are being made to understand the mechanisms of rock breakage and therefore fragmentation under relatively confined conditions. To minimize geometrical and geological effects, tests were conducted mainly on cylinders of magnetic mortar of size Ø140×280 mm and PETN cord with different strengths was used as explosive in a center hole, giving a specific charge between 0,2 and 2,6 kg/m3. The size distributions of the blasted material and the aggregate as well as the swelling of the cylinders have been measured. For the latter, a freezing-slicing method was developed. The results show that the confinement results in fragmentation being coarser when compared to that from free cylinders, and that the properties of the debris have a strong influence on the fragmentation and the swelling.

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  • 19.
    Johansson, Daniel
    et al.
    Luleå University of Technology.
    Ouchterlony, Finn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering - Swedish Blasting Research Centre.
    Nyberg, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering - Swedish Blasting Research Centre.
    Modellförsök med sprängning mot rasmassor: inverkan på styckefall och svällning2007In: Bergsprängningskommittén : diskussionsmöte BK 2007: protokoll från Bergsprängningskommitténs diskussionsmöte i Stockholm den 13 mars 2007, 2007, p. 105-120Conference paper (Other academic)
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  • 20.
    Johansson, Daniel
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Schunnesson, HåkanLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Twelfth International Symposium on Rock Fragmentation by Blasting: Fragblast 122018Conference proceedings (editor) (Refereed)
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  • 21.
    Johansson, Daniel
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Villegas, Tomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Ouchterlony, Finn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering - Swedish Blasting Research Centre.
    Dynamic blast compaction of some granular materials: small-scale tests and numerical modelling of a mining-related problem2010In: International Journal of Mining and Mineral Engineering, ISSN 1754-890X, E-ISSN 1754-8918, Vol. 2, no 2, p. 79-100Article in journal (Refereed)
    Abstract [en]

    Sub-Level Caving (SLC) is an important mass mining method, involving blasting of ore against granular material in the form of caving debris. The debris compaction due to blasting influences the caving process. Blasting tests were made on cylinders of magnetic mortar placed inside plastic cylinders and confined by packed granular material. By introducing the acoustic impedance between the mortar and the confining granular material, the compaction is found to depend on material, specific charge and physical properties of the debris with statistical analysis. The tests have shown to be a good input for numerical modelling of blast compaction.

  • 22.
    Lai, Frédéric
    et al.
    BRGM, 3 avenue Claude Guillemin, BP 36009, 45060, Orléans Cedex 2, France.
    Beylot, Antoine
    BRGM, 3 avenue Claude Guillemin, BP 36009, 45060, Orléans Cedex 2, France.
    Navarro, Rafael
    Minera de Orgiva, S.L., Polígono 13, parcela 1, 18400, Órgiva (Granada), Spain; CHARROCK Research Group, University of Salamanca, Plaza de los Caídos s/n, 37008, Salamanca, Spain.
    Schimek, Peter
    VA Erzberg GmbH, Erzberg 1, 8790, Eisenerz, Austria.
    Hartlieb, Philipp
    Montanuniversitaet Leoben, Franz-Josef Strasse 18, 8700, Leoben, Austria.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Segarra, Pablo
    Universidad Politécnica de Madrid – ETSI Minas y Energía, Ríos Rosas 21, 28003, Madrid, Spain.
    Amor, Celso
    Minera de Orgiva, S.L., Polígono 13, parcela 1, 18400, Órgiva (Granada), Spain.
    Villeneuve, Jacques
    BRGM, 3 avenue Claude Guillemin, BP 36009, 45060, Orléans Cedex 2, France.
    The environmental performance of mining operations: Comparison of alternative mining solutions in a life cycle perspective2021In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 315, article id 128030Article in journal (Refereed)
    Abstract [en]

    Mining represents the first step to the access to mineral resources. The impacts induced by such operations now contribute to the impacts of a wide range of goods and services, given the widespread use of these raw materials in the worldwide economy. In this context, this study aims at assessing the environmental performance of mining operations in a life cycle perspective, considering two currently operating mine sites: the Erzberg iron open-pit mine (Austria) and the Lujar fluorspar underground mine (Spain). In particular, this study aims at i) identifying the main environmental hotspots along the cradle-to-gate exploitation of mineral deposits in these two mines (“reference scenarios”), ii) assessing the environmental performance of two alternative mining solutions (“alternative scenarios”), respectively the use of alternative explosive compositions (including their associated air emissions) and the implementation of a new blast design method. This assessment relies on representative sets of data primarily drawn from on-site operations and experimental results, completed with other data sources to fill the gaps. The environmental impacts are characterized based on the European EF (Environmental Footprint) life cycle impact assessment method. Firstly, among the 16 impact categories considered, the production of 1 ton of iron concentrate (33.5% Fe) in the Erzberg mine in particular potentially induces a total of 8.75 kg CO2-eq. The consumption of ferrosilicon in the concentration step (main contributor to 8 impact categories out of 16), of steel in the comminution step (main contributor to 2 impact categories), and of diesel by the machinery necessary for loading/hauling the ore (main contributor to 3 impact categories) stand for the main environmental hotspots in the Erzberg case. Secondly, the production of 1 ton of fluorspar concentrate (79.2% CaF2) in the Lujar mine potentially induces a total of 174 kg CO2-eq. The consumption of diesel by the machinery and the on-site generators in the mining and loading/hauling steps (main contributor to 11 impact categories out of 16), along with the mine infrastructure/equipment (main contributor to 4 impact categories) are identified as the main environmental hotspots in the Lujar case. The implementation of both alternative mining solutions results in relatively limited environmental effects on the overall life cycle environmental performance of the Erzberg mining operations (less than 3% difference in terms of impacts). Finally, this study highlights that some challenges still remain to be addressed in order to better secure the use of life cycle assessment in the mining context, in particular in terms of data monitoring/measurement or impact assessment methods.

  • 23.
    Liaghat, Samaneh
    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.
    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.
    Ore grade prediction using informative features of MWD data2019In: Mining Goes Digital: Proceedings of the 39th International Symposium 'Application of Computers and Operations Research in the Mineral Industry' (APCOM 2019), June 4-6, 2019, Wroclaw, Poland / [ed] Christoph Mueller; Winfred Assibey-Bonsu; Ernest Baafi; Christoph Dauber; Chris Doran; Marek Jerzy Jaszczuk; Oleg Nagovitsyn, Taylor & Francis, 2019, p. 226-234Conference paper (Refereed)
    Abstract [en]

    Detailed knowledge of the content and geometrical variation of ore grade is essential in mining operations for production planning and economic analysis. Common ore grade specification methods, sampling and analysis are costly and time consuming. Measurement While Drilling (MWD) technique can directly extract grade information from the drilling process increasing data resolution and reducing cost.

    This study introduces a supervised feature selection method based on the Hilbert-Schmidt independence criterion to increase the accuracy of the results and decrease processing time. Potential of the method for recognizing the most effective and non-repetitive dimensions of input data has also been investigated. By exploiting the lower dimension data, a classification model is developed to map the parameter values to ore grade levels.

    Evaluation of the model using MWD data from LKAB’s Leveäniemi mine proved the effectiveness of the proposed feature selection and classification method.

  • 24.
    Manzoor, Sohail
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Danielsson, M.
    Ramböll, Sweden.
    Söderström, E.
    AFRY, Sweden.
    Schunnesson, Håkan
    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.
    Fredriksson, H.
    AFRY, Sweden.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Predicting rock fragmentation based on drill monitoring: A case study from Malmberget mine, Sweden2022In: Journal of the Southern African Institute of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 2411-9717, Vol. 122, no 3, p. 155-165Article in journal (Refereed)
    Abstract [en]

    Fragmentation analysis is an essential part of the optimization process in any mining operation. The costs of loading, hauling, and crushing the rock are strongly influenced by the size distribution of the blasted rock. Several direct and indirect methods are used to analyse or predict fragmentation, but none is entirely applicable to fragmentation assessment in sublevel caving mines, mainly because of the limitations imposed by the underground environment and the lack of all the required data to adequately describe the rock mass. Over the past few years, measurement while drilling (MWD) data has emerged as a potential tool to provide more information about the in-situ rock mass. This research investigated if MWD can be used to predict rock fragmentation in sublevel caving. The MWD data obtained from a sublevel caving mine in northern Sweden were used to find the relationship between rock fragmentation and the nature of the rock mass. The loading operation of the mine was filmed for more than 12 months to capture images of loaded load-haul-dump (LHD) buckets. The blasted material in those buckets was classified into four categories based on the median particle size (X50). The results showed a strongercorrelation for fine and medium fragmented material with rock type (MWD data) than coarser material. The paper presents a model for prediction of fragmentation, which concludes that it is possible to use MWD data for fragmentation predict ion.

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  • 25.
    Manzoor, Sohail
    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.
    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.
    Rock fragmentation variations with increasing extraction ratio in sublevel caving: a case study2022In: International Journal of Mining, Reclamation and Environment, ISSN 1748-0930, E-ISSN 1748-0949, Vol. 36, no 3, p. 159-173Article in journal (Refereed)
    Abstract [en]

    Variations in rock fragmentation are very likely to occur in a sublevel-caving operation. This study conducted a comprehensive test in an iron ore mine to monitor rock fragmentation. The results show a clear trend in fragmentation variations from start to end of production from a ring. These variations suggest an increase in coarse and oversized fragments with increasing material extraction from the rings that can be linked to increased overburden and drill hole deviations in the upper part of the rings. These problems can be addressed by shortening the drill hole length or directional drilling but need further investigations.

  • 26.
    Manzoor, Sohail
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Liaghat, Samaneh
    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.
    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.
    Establishing relationships between structural data from close-range terrestrial digital photogrammetry and measurement while drilling data2020In: Engineering Geology, ISSN 0013-7952, E-ISSN 1872-6917, Vol. 267, article id 105480Article in journal (Refereed)
    Abstract [en]

    Geologists, mine planners, geotechnical, and mining engineers always strive for maximum information to get a better insight of the rock mass before interacting with it. Over the recent decades, close-range terrestrial digital photogrammetry (CRTDP) has been increasingly used for data acquisition and to support the conventional methods for rock mass characterization. It provides a safe, time-saving and contact-free way to gather enough data to minimize user dependent biases. However, it requires an expensive camera, fieldwork and some software to extract the information from images. In addition, it can over-estimate the rock fracturing sometimes due to weathering of the rock face or poor blasting practices. Measurement while drilling (MWD) data include the responses of different drilling parameters to the variations in the rock mass. MWD data are produced in large quantity, as they come from every hole drilled. These data correspond to the inside variations of rock rather than the surface ones counted in photogrammetry.

    In this paper, structural data are obtained from different bench faces of an open pit mine using a commercial software package, ShapeMetriX3D (by 3GSM). These data are compared to the MWD data of the boreholes that were blasted to produce these bench faces to establish certain relationships between drilling parameters and rock mass structures. Half casts of the boreholes with MWD data were visible on the bench faces of the pre-split wall that allowed a better correlation. The results show abrupt changes in MWD parameters for open joints or cavities with some infilling material and overall increases or decreases in parameters for closely spaced bedding planes, fractures or foliations. The results are promising and suggest the method can be used to characterize the rock mass, modify the charging of explosives in blasting operations and facilitate the geological modeling of the rock mass.

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  • 27.
    Manzoor, Sohail
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Liaghat, Samaneh
    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.
    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.
    Rock mass characterization using MWD data and photogrammetry2019In: Mining goes Digital: Proceedings of the 39th International Symposium 'Application of Computers and Operations Research in the Mineral Industry' (APCOM 2019), June 4-6, 2019, Wroclaw, Poland / [ed] Christoph Mueller, Winfred Assibey-Bonsu, Ernest Baafi, Christoph Dauber, Chris Doran, Marek Jerzy Jaszczuk, Oleg Nagovitsyn, London: Taylor & Francis Group, 2019, p. 217-225Conference paper (Refereed)
    Abstract [en]

    Measurement while drilling data are produced in enormous quantity in underground and surface mines across the world. The data comprise parameters recorded during the drilling process, including penetration rate, rotation pressure, feed pressure, percussive pressure, damping pressure and flush pressure. MWD data are shown to be very useful for rock mass characterization, blasting applications and geological modelling of the rock mass. In this study, an open pit mine in Austria was selected for data collection as a part of SLIM project. The MWD data collected from drilling rigs were processed to identify different zones of rock mass, i.e. weak, fractured or competent rock. The results were compared to 3D images obtained by close-range terrestrial digital photogrammetry for validation; which showed a close agreement with each other. The method can be used to characterize the rock and to modify the charging of explosives in the boreholes for improved blasting results.

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  • 28.
    Navarro, Juan
    et al.
    Universidad Politécnica de Madrid – E.T.S.I. Minas y Energía, Madrid, Spain.
    Schunnesson, Håkan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Ghosh, Rajib
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Segarra, Pablo
    Universidad Politécnica de Madrid – E.T.S.I. Minas y Energía, Madrid, Spain.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Sanchidrián, José Ángel
    Universidad Politécnica de Madrid – E.T.S.I. Minas y Energía, Madrid, Spain.
    Application of drill-monitoring for chargeability assessment in sublevel caving2019In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 119, p. 180-192Article in journal (Refereed)
    Abstract [en]

    Currently, the charging procedure for sublevel caving mining is carried out with no prior information of the rock mass condition. Thus, engineers are blindsided to unexpected rock conditions and ill-prepared to address issues associated with collapsing boreholes. This results on charging problems and, as consequence, bad fragmentation of the rock after blasting which difficult ore loading and transportation as the gravity flow of the rock is reduced.

    This paper builds up the work done by Ghosh et al. (IJRMMS, 2018), to classify the geotechnical rock condition into five classes (solid rock, fractured rock, cave-in, minor and major cavity). From it, two applications based on the Measure While Drilling (MWD) technique have been developed: one for geotechnical rock condition of orebodies and the other for predicting the risk of collapse in boreholes. The work of Ghosh et al. has been improved into a geotechnical rock condition block model to simplify the quantitative assessment and automatic recognition of rock trends. A thorough correction of the MWD parameters has been also applied to minimize external influences other than the rock mass. From it, the risk of borehole collapses model has been developed by comparing different combinations of the geotechnical rock condition block-model with the charging length of 102 production fan-holes. The assessment of the number of collapsed and non-collapsed blastholes and the charging length/blasthole length ratio has been used to assign high, medium or low risk of collapse to each combination. The results predict collapses in the first half of the fan-holes for the high risk, collapses in the second half of the fan-hole for the medium risk and no collapses along the hole for the non-risk holes. The two models have been applied in large scale for two orebodies in the Malmberget mine, Sweden, which comprises 20 drifts and 5060 fan shape long-holes.

  • 29.
    Parida, Aditya
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Edelman, Martin
    Success of reliability centered maintenance (RCM) lies in its implementation: a case study2004In: Euromaintenance 2004: Libro de conferencias, Conference Proceedings : 17° Congreso Europeo de Mantenimiento, 17th European Maintenance Congress : 11th - 13th of May, 2004 Barcelona - Spain, Barcelona: Asociacion Espanola de Mantenimiento , 2004, p. 229-236Conference paper (Refereed)
  • 30.
    Petropoulos, Nikolaos
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Beyglou, Ali
    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.
    Novikov, Evgeny
    Nyberg, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Improved blasting performance through precise initiation2013In: EFEE-7th World Conference on Explosives & Blasting, Moscow: European Federation of Explosives Engineers , 2013, Vol. 1, p. 20-26Conference paper (Refereed)
    Abstract [en]

    Blast-induced fragmentation is an important factor in optimization of downstream processes in a mine. Several researchers believe that the fragmentation can be improved by means of precise short inter-hole delay times. Six full-scale trials with different inter-hole delay times of 1, 3, 6 and 42 ms (0.14, 0.42, 0.84 and 6 ms/m of burden, respectively) were conducted in Boliden Aitik open pit copper mine in Sweden. Electronic detonators were used for short inter-hole delay times, which correspond to different wave interactions between the neighboring blast holes. All the trials were carried out in more or less similar geological conditions. MWD data, swelling, fragmentation and crusher efficiency have been evaluated in the trials. Based on these trials, the short inter-hole delay times did not have a significant effect on fragmentation, swelling and crushability. However, a reduced number of boulders was observed for short delays, suggesting that the coarse region of the distribution curve was influenced rather than the fine part of it.

  • 31.
    Petropoulos, Nikolaos
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Beyglou, Ali
    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.
    Nyberg, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Novikov, Evgeny
    Boliden Mineral AB.
    Fragmentation by blasting through precise initiation: Full scale trials at the Aitik Copper mine2014In: Blasting and Fragmentation, ISSN 1937-6359, Vol. 8, no 2, p. 87-100Article in journal (Refereed)
    Abstract [en]

    Fragmentation is an important factor for improving downstream processes in mine operations. Six trials have been conducted at the Aitik copper mine to investigate the effect of ultra-short inter-hole delay times, i.e. smaller than 1 ms/m of burden, on fragmentation. Swelling, MWD data and crusher efficiency were also evaluated for trials. According to the results, the effect of examined short inter-hole delay times, i.e. 0.14 to 0.86 ms/m of burden, on fragmentation was found to be marginal. Delay time of 0.43 ms/m of burden resulted in slightly finer fragmentation and larger swell; however, the effect of short delays was overshadowed by the effect of small variations in specific charge.

  • 32.
    Petropoulos, Nikolaos
    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.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Crushed aggregate response upon impact in dry and wet conditions2017In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 7, no 3, p. 1-22Article in journal (Refereed)
    Abstract [en]

    This paper presents results from a series of impact tests upon coarse-grained crushed aggregate. The material has been evaluated for two conditions, i.e. dry and wet (pendular state). Three main sets of test configurations were used with respect to compactive effort (low, medium and high) which was defined by the impact velocity of a drop hammer. Three accelerometers were installed in an impact machine to measure deceleration of the drop hammer and accelerations in the tested material at three different locations. The studied parameters were density, compaction, angle of repose, critical angle and particle size distribution. The results showed that the wet material gives larger density as well as critical angle. However, there was no discernible change in particle size distribution.

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  • 33.
    Petropoulos, Nikolaos
    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.
    Nyberg, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Novikov, Evgeny
    Beyglou, Ali
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Improved blasting results through precise initiation: results from field trials at the Aitik open pit mine2013Report (Refereed)
    Abstract [en]

    Blast-induced fragmentation plays a leading role on mining efficiency, hence many studies have been conducted in order to understand the mechanisms behind rock breakage and to improve the fragmentation. This report presents the results from field tests conducted at the Aitik mine belonging to Boliden Mineral AB in Sweden, which is part of a project called Vinnova. The project aims to evaluate the effects of short delay time blasting on fragmentation and other post-blast parameters which influence the comminution process, e.g. swelling and crushing.A total number of 6 benches were assigned for trials with different inter-hole delay times. Two of the benches were blasted with pyrotechnic Nonel caps and were used as references for further comparisons. Two benches were blasted with 1 ms of inter-hole delay time by use of electronic detonators. Two other benches were also blasted by electronic detonators, but with 3 ms and 6 ms of inter-hole delay time respectively. MWD (Measure While Drilling) system was used to log and analyze the drilling process in order to investigate the penetration rate and specific energy of drilling, which represent the hardness of the rock. GPS (Global Positioning System) and RTK (Real time Kinematic System) were used for measurements of benches’ swelling. The blasts were also filmed using a high-speed camera. Image analysis with Split-Desktop software was used to analyze the fragmentation of the rock after blasts. A series of images was shot from trucks carrying the ore and was later analyzed to obtain the fragmentation for each bench. Minestar integrated operation and mobile equipment management system was used to log the data from the fleet in the mine. The data were later used together with the crusher energy consumption logs to evaluate the energy efficiency of the crushing process for the ore from each bench.The tests showed that the inter-hole delay time of 3 ms resulted in the finest fragmentation among all benches; all examined values i.e. x50, x80 and xmax showed improvements upon other benches. However, the crushing energy of the ore from this trial was the highest among all. Two trials with 1 ms inter-hole delay time did not result in any significant variation compared to reference benches. The difference in x50 values were ignorable, the same is true for crushing energy of the mentioned trials. The bench with inter-hole delay time of 6 ms resulted in the lowest crushing energy among other trials. However, the bench gave more boulders and coarser fragmentation compared to reference benches.Altogether, the results did not lead to any solid conclusion regarding the effect of the short delay times on fragmentation. Such ambiguity might be resulted by various sources of errors in data acquisition and analysis, as well as uncertainties regarding geology of the test area. In order to investigate the effect of delay times on blast results, more trials with more detailed data acquisition method is necessary.

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  • 34.
    Petropoulos, Nikolaos
    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.
    Ouchterlony, Finn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Fragmentation under different confinement conditions and the burden behaviour: small scale tests2012In: Measurement and Analysis of Blast Fragmentation: Workshop Hosted by FRAGBLAST 10 - The 10th International Symposium on Rock Fragmentation by Blasting / [ed] Jose A. Sanchidrian Blanco; Ashok Kumar Singh, Boca Raton, Fla.: CRC Press/Balkema , 2012, p. 61-70Conference paper (Refereed)
    Abstract [en]

    Small scale-tests have been performed on magnetic mortar blocks to investigate the influence of delay times, specific charge and firing pattern on fragmentation both when the burden is free and when confined by debris simulating the confined conditions of a SLC-blast ring and to study the burden behavior during blasting by implementing dynamic methods of measurements. The dimensions of the test blocks were 660 ×270 ×210 mm (L ×W ×H). Two different blast hole patterns, 2 rows with 5 holes with a burden of 70 mm (S/B ×1.6) and 3 rows with 7 holes with a burden of 58.3 mm (S/B ×1.4). A complete analysis regarding the influence of different delay times ranging from 0 to 4.1 ms/m of burden, different specific charges and different firing patterns on fragmentation has been made, based upon 22 blocks.

  • 35.
    Petropoulos, Nikolaos
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mihaylov, Dimitar
    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.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    A Suggested Method for the Study of Crushed Aggregate Response to Dynamic Compaction2017In: Electronic Journal of Geotechnical Engineering, E-ISSN 1089-3032, Vol. 22, no 02, p. 387-406Article in journal (Refereed)
    Abstract [en]

    Soil improvement by dynamic compaction has been extensively used all around the world in large civil engineering projects. Limited number of laboratory tests has been conducted to study the behavior of soil material under dynamic loading. A suggested method is presented in this paper which includes a new laboratory apparatus and experimental procedure as well as data analysis. The suggested impact machine is a drop hammer type machine, it can host up to 37.5 mm particle size in a coarse-grained aggregate matrix independent of its conditions, i.e. saturated or unsaturated, it is also flexible in terms of weight and size of the drop hammer and the mold. The machine is equipped with accelerometers for continuous monitoring of the sample’s behavior during impact. The experimental procedure shows the steps for conducting consistent dynamic compaction tests. It also describes how the measurements should be conducted. These measured quantities correspond to key parameters such as density, angle of repose and compaction. Finally, a case example demonstrates the function of the machine and the analysis of the recorded data.

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    fulltext
  • 36.
    Petropoulos, Nikolaos
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mihaylov, Dimitar
    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.
    Wimmer, Matthias
    Nordqvist, Anders
    Mining Technology R and D, LKAB Kiruna Mine.
    Design of equipment for dynamic burden measurements2015In: 11th International Symposium on Rock Fragmentation by Blasting: FragBlast11, Carlton VIC: The Australasian Institute of Mining and Metallurgy, 2015, p. 493-500Conference paper (Refereed)
    Abstract [en]

    The flowability of the caved rock masses in the sublevel caving (SLC) mining method is of greatimportance. During the blasting process of a SLC-ring, the caved rock mass in front of the ring iscompacted. As a result of this compaction, the mechanical properties of the fractured rock masseschange, for example void ratio, angle of internal friction and structure of the compacted material.The changed mechanical properties of caved rock mass and recent blasted material can influencethe mobility of the material, which could result in blockage of the flow path of the material.The identification of the involved mechanisms in this process can be done after a series of testsin different scales. However, there is no available equipment for dynamic measurements duringblasting, ie velocity and displacement of the burden and in the caved masses. This study focuses onthe development and laboratory evaluation of a measuring system that can be installed in a borehole.The first trial was carried out in a pillar, where two blastholes had been drilled (9.5 m) parallel withthe drift and two measuring holes (16.5 m) were perpendicular to the drift. Two measuring systemswere installed in the measuring holes. Some preliminary tests were carried out to find suitableinitiation procedures for the emulsion explosive. Applicability and robustness of the developedmeasuring system were also evaluated. In addition to these tests, an expandable cement mixture wasdeveloped to firmly anchor the measuring systems in the boreholes. The measuring system consistsof an anchor, armoured cable in a pulling tube and a protective case. The anchor is equipped withuniaxial and triaxial accelerometers. A potentiometric measuring system for displacement up to 2 mis installed at the end of the pulling tube and connected to an extendable spiral cable. All sensorsare connected to a data acquisition system (DAS). Both measuring systems have their own DAS toacquire data in case of failure of one of the systems. The measuring system was tested in laboratoryconditions with impact velocity up to 10 m/s. It was proven to be functional and gave reliable results.

  • 37.
    Petropoulos, Nikolaos
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Wimmer, Matthias
    LKAB, Kiruna.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Compaction of confining materials in pillar blast tests2018In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 51, no 6, p. 1907-1919Article in journal (Refereed)
    Abstract [en]

    Two confined pillar tests were conducted at the Kiirunavaara mine to investigate the degree of compaction of three materials, i.e., 0–32-mm backfilled material, a blend of ore and waste material and caved material. Two blastholes were drilled parallel to each pillar wall, and several measurement holes were drilled in between the blastholes through each pillar. Both the measurement holes and backfilled materials, except the caved material, were instrumented. Two types of measurements were taken: dynamic measurements with accelerometers, and static measurements which considered the location of the instrumentation pre- and post-blast. Dynamic measurements involved the burden movement and the confining material behavior, and static measurements contained the final location of sensors inside and the angle of repose of the confining material. The results showed that the size distribution of the confining material affects its behavior under dynamic loading. The backfilled materials showed an apparent cohesion forming an agglomeration on the surface of the blasted burden. The burden moved as one slab due to simultaneous detonation. A gap was formed between the blasted burden and the new face. This gap was partially filled with burden erosion material which was finer fragmented than the blasted burden material.

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  • 38.
    Rodriguez San Miguel, Carlota
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Petropoulos, Nikolaos
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. LKAB, Sweden.
    Stenman, Ulf
    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.
    The environmental impact of AN prills on emulsion explosives2024In: Proceedings of the Fiftieth Annual Conference on Explosives and Blasting Technique, International Society of Explosives Engineers , 2024Conference paper (Refereed)
  • 39.
    San Miguel, Carlota Rodriguez
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Petropoulos, Nikolaos
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. LKAB, Sweden.
    Stenman, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Yi, Changping
    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.
    Development of a methodology for measuring crack growth by blasting using non-contact techniques2023In: 12th World Conference on Explosives and Blasting: Dublin Conference Proceedings 2023 / [ed] Holmberg, R. et al., European Federation of Explosives Engineers , 2023, , p. 45-54p. 45-54Conference paper (Refereed)
  • 40.
    Schunnesson, Håkan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Shekhar, Gurmeet
    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.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    A review of mining practices for surface support: an international survey2019In: Ground Support 2019: Proceedings of the Ninth International Symposium on Ground Support in Mining and Underground Construction / [ed] John Hadjigeorgiou; Marty Hudyma, Australian Centre for Geomechanics (ACG), , 2019, p. 283-293Conference paper (Refereed)
    Abstract [en]

    This paper reviews mining practices for surface support and identifies four key areas that need attention. An international survey was conducted as part of the Mining Initiative on Ground Support Systems and Equipment III project from 2017 to 2018. The survey used a standardised, web-based questionnaire adapted for personal computers and smartphones. The survey was distributed globally, with data collected from 58 underground mines with different mining conditions and challenges. The results highlight the challenges with regard to safety and automation of surface support for different rock conditions and the advantages and disadvantages of various machines (face drills versus mechanised dedicated bolters versus semi-mechanised bolters) used to install surface support. The survey also shows the ambiguity in the mining community with regard to productivity of mine support. This paper presents an approach for collecting technical data through an online tool, which is inexpensive and effective.

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    Shekhar_ground support_2019
  • 41.
    Sjöberg, Jonny
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Schill, Mikael
    DYNAmore Nordic AB, Linköping.
    Hilding, Daniel
    DYNAmore Nordic AB, Linköping.
    Yi, Changping
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nyberg, Ulf
    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.
    Computer simulations of blasting with precise initiation2012Conference paper (Refereed)
    Abstract [en]

    Using blasting caps with electronic delay units, it has become possible to employ wave superposition in rock blasting. This paper presents computer simulations to investigate the hypothesis that fragmentation is improved in areas between blast holes where the tensile waves meet, overlap and interact. In this study, a numerical methodology using the code LS-DYNA was developed. LS-DYNA is a commercially available multi-purpose finite-element code, which is well suited to various types of dynamic modeling. Two different element formulations were used — Euler formulation in, and close to, the blast hole, and Lagrange formulation in the rock volume farther from the blast hole. The models used have a resolution (element size) of 50 mm and comprise approximately 20 million elements. Single and dual blast hole configurations have been studied, and a methodology to calculate possible fragmentation based on model interpretation was developed. The results showed that the amount of explosives and the blast hole spacing had the largest effect on fragmentation. The effect of varying delay times was small and local, implying that a significant increase in fragmentation should not be expected through wave superposition.

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    FULLTEXT01
  • 42.
    van Eldert, Jeroen
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Ittner, Henrik
    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.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Evaluation of Alternative Techniques for Excavation Damage Characterization2016In: ITA-AITES World Tunnel Congress 2016, WTC 2016 / [ed] Society for Mining, Metallurgy & Exploration (SME), United States of America, 2016, Vol. 2, p. 1168-1177Conference paper (Refereed)
    Abstract [en]

    Numerous aspects of underground construction, from structural stability to construction costs, depended on the tunnel quality, including blast damage and the Excavation Damage Zone. Accurately quantifying the extent and severity of damaged rock is a problem. Recent technical developments in the field of Measurement While Drilling (MWD), including software for on-board logging and on-site analysis, have shown potential for rock-mass characterization. Ground Penetrating Radar (GPR) and P-wave velocity measurement have also improved and show similar potential. This paper explores the use of MWD, GPR and P-wave velocity measurements and uses them in techniques for excavation damage characterization and prediction. The paper is based on data collected from a small underground wastecollection site in central Stockholm, Sweden. The data is correlated against rock-mass characteristics and their responses are evaluated. Results indicate potential for excavation damage characterization for all tested techniques, which could minimize blasting damage and improve the over-all tunnel quality.

  • 43.
    van Eldert, Jeroen
    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.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    The History and Future of Rock Mass Characterisation by Drilling in Drifting: From sledgehammer to PC-tablet2017In: Mine Planning and Equipment Selection (MPES 2017): Proceeding of the 26th International Symposium on Mine Planning and Equipment Selection Luleå, Sweden, August 29-31, 2017 / [ed] Behzad Ghodrati, Uday Kumar, Håkan Schunnesson, Luleå: Luleå tekniska universitet, 2017, p. 99-106Conference paper (Refereed)
    Abstract [en]

    In underground construction projects problematic rock mass conditions are one of the major issues causing cost overruns during the excavation phase. Before a tunneling project starts the rock mass is roughly characterized by a pre-investigation. However, in many cases, these pre-investigation does not portray the rock mass characteristics accurately and do not predict local anomalies in the subsurface. Therefore there is a need for new rock mass characterization methods that can reduce uncertainties and improve the overall tunneling process.

    In the end of the 1880s, rock mass characterization based on manual drill data was investigated and rock masses were quantified using drillability. Since then, the technology has significantly changed with the introduction of hydraulic rock drills, computerized drill rigs, and advanced rock mass classification systems based on drill parameters. Nowadays, automatic drill logging systems and drilling data processing software packages are widely available and commonly used in Scandinavian tunneling projects.

    This technology uses drilling parameters to characterize the rock mass. However, monitored drill parameters are influenced not only by the variations in the properties of the penetrated rock mass but also by the operator and the rig control system that continuously control the applied forces to optimize drilling and prevent jamming. In order to be useful for geomechanical purposes, the drilling data needs to be filtered, normalized and analyzed to refine the rock related response from responses caused by other influencing factors. If successful the data might be used to determine hardness, fracturing and water indicators.

    Even though the technology has shown high potential in laboratory tests and field trials, it is not an obvious choice for all tunneling projects. In this paper, the background of the technology are described and the potential for the future outlined, concluding that the technique probably will be used more extensively in the future. 

  • 44.
    van Eldert, Jeroen
    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.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Saiang, David
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Application of Measurement While Drilling Technology to Predict Rock Mass Quality and Rock Support for Tunnelling2020In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 53, no 3, p. 1349-1358Article in journal (Refereed)
    Abstract [en]

    A tunnelling project is normally initiated with a site investigation to determine the in situ rock mass conditions and to generate the basis for the tunnel design and rock support. However, since site investigations often are based on limited information (surface mapping, geophysical profiles, few bore holes, etc.), the estimation of the rock mass conditions may contain inaccuracies, resulting in underestimating the required rock support. The study hypothesised that these inaccuracies could be reduced using Measurement While Drilling (MWD) technology to assist in the decision-making process. A case study of two tunnels in the Stockholm bypass found the rock mass quality was severely overestimated by the site investigation; more than 45% of the investigated sections had a lower rock mass quality than expected. MWD data were recorded in 25 m grout holes and 6 m blast holes. The MWD data were normalised so that the long grout holes with larger hole diameters and the shorter blast holes with smaller hole diameters gave similar results. With normalised MWD data, it was possible to mimic the tunnel contour mapping; results showed good correlation with mapped Q-value and installed rock support. MWD technology can improve the accuracy of forecasting the rock mass ahead of the face. It can bridge the information gap between the early, somewhat uncertain geotechnical site investigation and the geological mapping done after excavation to optimise rock support.

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  • 45.
    van Eldert, Jeroen
    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.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Saiang, David
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Measurement While Drilling (MWD) technology for blasting damage calculation2018In: FRAGBLAST 12: 12th International Symposium on Rock Fragmentation by Blasting, Luleå, Sweden 11-13 June 2018 / [ed] Håkan Schunnesson, Daniel Johansson, Luleå University of Technology, 2018, p. 139-148Conference paper (Refereed)
    Abstract [en]

    For all underground excavations it is important to reduce both blasting induced damage and the blast-induced Excavation Damage Zone (EDZ). Except for the operational parameters, the geomechanical conditions of the rock mass have a significant impact on the amount of over-break in tunnel constructions. Today, direct measurements of the EDZ are difficult to perform and are therefore not commonly done at construction sites. This paper investigates the application of Measurement While Drilling (MWD) technology to predict the extent of the EDZ, using data from four Swedish tunnel excavations. The depth of this zone is determined by Ground Penetration Radar (GPR), P-wave velocity measurements and Rock Quality Designation (RQD) for drill cores. The correlation between MWD, operational parameters and EDZ was evaluated using multiple linear regression. The study shows that the EDZ is heavily influenced by rock mass conditions but also by operational parameters. Furthermore, the EDZ depth based on GPR measurements, can be reasonable well predicted using MWD data.

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  • 46.
    Varannai, Balázs
    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.
    Crusher to Mill Transportation Time Calculation—The Aitik Case2022In: Minerals, E-ISSN 2075-163X, Vol. 12, no 2, article id 147Article in journal (Refereed)
    Abstract [en]

    Comminution is a major contributor to the production costs in a mining operation. There-fore, process optimization in comminution can significantly improve cost efficiency. The mine-to-mill concept can be utilized to optimize the comminution chain from blasting to grinding. In order to evaluate the mill performance of the ore from a specific location of the deposit, a direct link needs to be established between the mill performance and the place of origin in the mine. Today, technology enables the accurate positioning of drilling, loading, and dumping points in the mine, making the ore flow between loading and crushing more transparent. However, the material flow from the crusher to the mill is not yet fully understood and monitored. This paper presents the development of an ore transportation model, based on the virtual silo concept, between the crusher and the mill for Boliden’s Aitik mine in northern Sweden. The proposed model helps to establish a link between in situ ore location and mill performance. Two transportation time calculations are used, one based on mass balance, and one based on momentary values. Historical data are used to test the capabilities of the model and the results are compared with the transportation time calculated from the mean capacity values, commonly used in previous studies to connect mill parameters with in situ ore location. The comparison of the results show that the mean parameter-based values can be as much as 50% lower than the transportation times, even in normal operation. In the tested times, the transportation time based on momentary values systematically underestimated the cumulated times. The developed model will also serve as a starting point to analyze the effect of geotechnical parameters, in addition to drill and blast design, on the mill performance of the blasted ore.

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  • 47.
    Yi, Changping
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Iravani, Armin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Gómez, Santiago
    Universidad Politécnica de Madrid, Spain.
    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.
    Wimmer, Matthias
    Luossavaara-Kiirunavaara AB, Sweden.
    Voronoi-based numerical investigation of fragmentation and gravity flow of SLC2023Conference paper (Refereed)
  • 48.
    Yi, Changping
    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.
    Discrete Element Modelling of Blast Fragmentation of a Mortar Cylinder2015Conference paper (Refereed)
    Abstract [en]

    Blasting techniques are widely used to fragment rock masses into smaller pieces. Numerical modelling is an efficient method employed by many researchers in the blasting field. It is difficult for a conventional continuum-based approach such as the finite element method (FEM) to model the rock fragmentation by blasting and the expansion work on the rock by explosive and its detonation products. In this paper, the particle blast method (PBM) was employed to model the behaviour of the detonation and a bonded particle model (BPM) was used to model the brittle material to be blasted. A mortar cylinder with a centrally placed hole for the explosive was modelled and the results were compared to the experimental data. The blast process from crack initiation to fragment formation was analysed. The influence of coupling ratio on fragmentation was also investigated.

  • 49.
    Yi, Changping
    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.
    Greberg, Jenny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Effects of in-situ stresses on the fracturing of rock by blasting2018In: Computers and geotechnics, ISSN 0266-352X, E-ISSN 1873-7633, Vol. 104, p. 321-330Article in journal (Refereed)
    Abstract [en]

    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.

  • 50.
    Yi, Changping
    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.
    Nyberg, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Numerical investigation for timing effects on fragmentation based on a coupled FEM-BPM-PBM model2018In: FRAGBLAST 12: 12th International Symposium on Rock Fragmentation by Blasting, Luleå, Sweden 11-13 June 2018 / [ed] Håkan Schunnesson, Daniel Johansson, Luleå University of Technology, 2018, p. 641-648Conference paper (Refereed)
    Abstract [en]

    A series of small-scale laboratory tests were carried out to investigate the effects of short delay times on fragmentation. The aim is to test the hypothesis that improve fragmentation through stress wave superposition. These tests have subsequently been modeled using a coupled FEM-BPM-PBM model in LS-DYNA code. In the model, the remaining rock is represented by a finite element model (FEM) and the rock to be blasted is represented by a bonded particle model (BPM). The detonation of explosive is described with a particle blast method (PBM). The fragment size distribution was obtained with a code developed in Perl programming language. The numerical results showed that although the short delay times induced improved fragmentation compared to the simultaneous initiation, the longer delay times also resulted in improved fragmentation, implying that stress wave superposition may not be the primary factor governing fragmentation.

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