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Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.ORCID iD: 0000-0002-8024-435X 2016 (English)Licentiate thesis, comprehensive summary (Other academic)

Abstract [en] : Open pit mines constitute more than half of global minerals production. Yet most of the large, high-grade, and close to the surface deposits have been depleted or are currently in production. Besides, volatility in commodity prices and stringent environmental regulations limit the up-scaling expansions in large open pits. Consequently, the mines are determined to increase their operational efficiency in order to thrive. This has recently led to major metallurgical improvements in the processing of ores; whereas the improvements in mining of the said ores are relatively overdue in terms of efficiency and technological advancement. This thesis concentrates on the mining activities and their efficiency in open pits with a focus on drilling, blasting, loading, and crushing. As all of these tasks revolve around the fragmentation of run-of-mine ore, their relationships and efficiencies are explored within the context of fragmentation.Fragmentation is a result of complex interactions between rockmass, blasting geometry, explosive, and timing sequence of blast holes. The influence of rockmass and timing sequence on fragmentation and efficiency are explored, as well as the target fragmentation for efficient loading and crushing. Moreover, the techniques for measuring fragmentation are evaluated as to whether they can benefit mines in terms of efficiency. As the circumstances in open pits are essentially site-specific, these issues are addressed as a case study of the Aitik mine in Sweden.The research comprised four elements. First, the influence of rockmass fractures on blast results and downstream efficiency was evaluated via full-scale field trials. The fractures in and around the case study mine were mapped using a photogrammetric technique and six production blasts were adapted to the major fracture sets to evaluate the effect of initiation direction on downstream efficiency. Second, the influence of the timing sequence of blast holes was explored within the theories of stress waves interaction and their consequent effect on fragmentation. Theoretical and numerical solutions were accompanied by six field trials in full-scale to evaluate the influence of short delay times on fragmentation and efficiency. Third, an empirical study was conducted to correlate fragmentation to the efficiency of loading and crushing; this was done to define a target fragmentation for the studied case. Finally, the techniques to assess fragmentation were discussed both quantitatively and qualitatively.The findings indicated that rockmass fractures have a significant influence on the quality of blasts and efficiency of downstream tasks. In the case study mine, adjustments to orientation of drill pattern and initiation direction of blasts suggested that careful experimentation in this regard can yield a favourable initiation direction with respect to existing discontinuities. Finer fragmentation and higher loading efficiencies can be achieved by adapting the blast designs to the existing fractures, which can lead to significant savings in the long run. On the contrary, the influence of stress waves interaction on blast results turned out to be marginal. Neither the theoretical and numerical solutions nor the field trials showed any significant improvements in blast results from short delays. In fact, it was found rather implausible to expect any noticeable improvements by using short delays.The empirical method to evaluate target fragmentation proved useful as well. It was shown that by incorporating different data from various sources in a mine, one can follow the ore from muckpile to loaders and then to crushers. Having a qualitative understanding of the fragmentation, and by developing tools to measure efficiency, one can estimate what fragmentation is most favourable for an efficient operation. Finally, two image-based methods to assess fragmentation were discussed in terms of repeatability and statistical significance. It was found that the scatter in both methods is rather large, introducing a certain ambiguity in representativeness of their results. Admittedly, it was found that in matters of long-term efficiency, the number, size and representativeness of assessed samples are of more importance compared to the accuracy of individual measurements.

Place, publisher, year, edition, pages: Luleå, 2016. , 60 p.

Series : Licentiate thesis / Luleå University of Technology, ISSN 1402-1757

National Category : Other Civil Engineering

Research subject: Mining and Rock Engineering

Identifiers: URN: urn:nbn:se:ltu:diva-59524ISBN: 978-91-7583-698-0 (print)ISBN: 978-91-7583-699-7 (electronic)OAI: oai:DiVA.org:ltu-59524DiVA: diva2:1033097

Presentation : 2016-11-10, F1031, Luleå, 10:00

Opponent : Segarra, Pablo, Docent

Supervisors : Schunnesson, Håkan, ProfessorLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.

Funder: VINNOVA, 1833218 Available from: 2016-10-06 Created: 2016-10-05 Last updated: 2016-10-19Bibliographically approved

List of papers : 1. Stress wave interaction between two adjacent blast holesOpen this publication in new window or tab >>Stress wave interaction between two adjacent blast holesYi, ChangpingLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.Johansson, DanielLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.Nyberg, UlfLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.Beyglou, AliLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.2016 (English)In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 49, no 5, 1803-1812 p.Article in journal (Refereed) Published

Abstract [en]: Rock fragmentation by blasting is determined by the level and state of stress in the rock mass subjected to blasting. With the application of electronic detonators, some researchers stated that it is possible to achieve improved fragmentation through stress wave superposition with very short delay times. This hypothesis was studied through theoretical analysis in the paper. First, the stress in rock mass induced by a single-hole shot was analyzed with the assumptions of infinite velocity of detonation and infinite charge length. Based on the stress analysis of a single-hole shot, the stress history and tensile stress distribution between two adjacent holes were presented for cases of simultaneous initiation and 1 ms delayed initiation via stress superposition. The results indicated that the stress wave interaction is local around the collision point. Then, the tensile stress distribution at the extended line of two adjacent blast holes was analyzed for a case of 2 ms delay. The analytical results showed that the tensile stress on the extended line increases due to the stress wave superposition under the assumption that the influence of neighboring blast hole on the stress wave propagation can be neglected. However, the numerical results indicated that this assumption is unreasonable and yields contrary results. The feasibility of improving fragmentation via stress wave interaction with precise initiation was also discussed. The analysis in this paper does not support that the interaction of stress waves improves the fragmentation.

National Category : Other Civil Engineering

Research subject : Mining and Rock Engineering

Identifiers: urn:nbn:se:ltu:diva-10010 (URN)10.1007/s00603-015-0876-x (DOI)8c34946d-51ee-48da-a361-eeec0b0892a6 (Local ID)8c34946d-51ee-48da-a361-eeec0b0892a6 (Archive number)8c34946d-51ee-48da-a361-eeec0b0892a6 (OAI)

Note: Validerad; 2016; Nivå 2; 20151015 (chayir)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2016-10-05Bibliographically approved 2. Fragmentation by blasting through precise initiation: Full scale trials at the Aitik Copper mineOpen this publication in new window or tab >>Fragmentation by blasting through precise initiation: Full scale trials at the Aitik Copper minePetropoulos, NikolaosLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.Beyglou, AliLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.Johansson, DanielLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.Nyberg, UlfLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.Novikov, EvgenyBoliden Mineral AB.Show others

.2014 (English)In: Blasting and Fragmentation, ISSN 1937-6359, Vol. 8, no 2, 87-100 p.Article in journal (Refereed) Published

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.

Keyword: Civil engineering and architecture - Geoengineering and mining engineering, Samhällsbyggnadsteknik och arkitektur - Geoteknik och gruvteknik

National Category : Other Civil Engineering

Research subject : Mining and Rock Engineering

Identifiers: urn:nbn:se:ltu:diva-11503 (URN)a7e1e547-49e7-46d1-9ce9-70fe7168f052 (Local ID)a7e1e547-49e7-46d1-9ce9-70fe7168f052 (Archive number)a7e1e547-49e7-46d1-9ce9-70fe7168f052 (OAI)

Note: Validerad; 2015; Nivå 1; 20150127 (nikpet)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-02-15Bibliographically approved 3. Adjusting Initiation Direction to Domains of Rock Mass Discontinuities in Aitik Open Pit MineOpen this publication in new window or tab >>Adjusting Initiation Direction to Domains of Rock Mass Discontinuities in Aitik Open Pit MineBeyglou, AliLuleå 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.Johansson, DanielLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.Johansson, NilsBoliden Mineral AB.2015 (English)In: 11th International Symposium on Rock Fragmentation by Blasting: Fragblast11, Carlton, Vic: The Australasian Institute of Mining and Metallurgy, 2015, 385-391 p.Conference paper, Published 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.

Place, publisher, year, edition, pages : Carlton, Vic: The Australasian Institute of Mining and Metallurgy, 2015

National Category : Other Civil Engineering

Research subject : Mining and Rock Engineering

Identifiers: urn:nbn:se:ltu:diva-29280 (URN)2b3dcd9d-cf05-4266-b374-cdd02102fce6 (Local ID)9781925100327 (ISBN)2b3dcd9d-cf05-4266-b374-cdd02102fce6 (Archive number)2b3dcd9d-cf05-4266-b374-cdd02102fce6 (OAI)

Conference: International Symposium on Rock Fragmentation by Blasting : 24/08/2015 - 25/08/2015

Note: Godkänd; 2015; 20150915 (alibey)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2016-10-05Bibliographically approved



Autor: Beyglou, Ali

Fuente: http://ltu.diva-portal.org/







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