| 1. |
- Ahmadi, Alireza, et al.
(författare)
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Selection of maintenance strategy, using analytical hierarchy process
- 2009
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Ingår i: Communications in Dependability and Quality Management. - 1450-7196. ; 12:1, s. 121-132
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Tidskriftsartikel (refereegranskat)abstract
- Selection of appropriate maintenance strategy is key to economic viability of aviation and manufacturing industries. The study discusses and presents an approach to facilitate the selection of the most appropriate maintenance strategy on the basis of the cost-benefit analysis by using Analytical Hierarchical Process (AHP). The goal is to select the most cost-effective alternative, among Run-To-Failure (RTF), Preventive Maintenance (PM), incorporating Prognostic Health Management(PHM) capability, or any possible Design-Out Maintenance (DOM) strategies, which positively affects on aircraft operational availability. In this paper we proposed a stepwise algorithm to guide the selection process, based on two criteria of operational availability (benefit) and cost of failure.
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| 2. |
- Appelgren, J, et al.
(författare)
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Automation and smart drill rigs
- 2006
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Ingår i: Mine planning and equipment selection 2006. - : Fiordo.
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Konferensbidrag (refereegranskat)
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| 3. |
- Arasteh khouy, Iman, et al.
(författare)
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Evaluation of track geometry degradation in swedish heavy haul railroad - A case study
- 2012
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Ingår i: International Journal of COMADEM. - 1363-7681. ; 15:2, s. 11-16
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Tidskriftsartikel (refereegranskat)abstract
- The measurement and improvement of track quality are key issues in determining both the time and cost of railway maintenance. Efficient track geometry maintenance ensures optimum allocation of limited maintenance resources and has an enormous effect on maintenance efficiency. Applying the appropriate tamping strategy also helps reduce maintenance costs, making operations more cost effective and leading to increased safety and passenger comfort. In this paper, track geometry data from the iron ore line in northern Sweden, which handles both passenger and freight trains, are used to calculate track quality degradation trend in a cold climate. The paper describes Trafikverket’s (Swedish Transport Administration) tamping strategy and illustrates the distribution of safety failures in different seasons. It also analyses the track geometry degradation and discuss about the possible reasons for distribution of failures over a year and along the track.
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| 4. |
- Arasteh Khouy, Iman, et al.
(författare)
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Evaluation of track geometry maintenance for a heavy haul railroad in Sweden: A case study
- 2014
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Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : SAGE Publications. - 0954-4097 .- 2041-3017. ; 228:5, s. 496-503
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Tidskriftsartikel (refereegranskat)abstract
- The measurement and improvement of track quality are key issues in determining both the restoration time and cost of railway maintenance. Applying the optimal tamping strategy helps reduce maintenance costs, making operations more cost effective and leading to increased safety and passenger comfort. In this paper, track geometry data from the iron ore line (Malmbanan) in northern Sweden, which handles both passenger and freight trains, are used to evaluate track geometry maintenance in cold climate. The paper describes Trafikverket’s (Swedish Transport Administration) tamping strategy and evaluates its effectiveness in measuring, reporting, and improving track quality. Finally, it evaluates the performance of the maintenance contractor and discusses the importance of the functional requirements stated in the outsourcing contracts.
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| 5. |
- Arasteh khouy, Iman, et al.
(författare)
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Optimisation of track geometry inspection interval
- 2014
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Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : SAGE Publications. - 0954-4097 .- 2041-3017. ; 228:5, s. 546-556
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Tidskriftsartikel (refereegranskat)abstract
- The measurement and improvement of track quality are key issues in determining the time at which railway maintenance must be performed and its cost. Efficient track maintenance ensures optimum allocation of limited maintenance resources which has an enormous effect on maintenance efficiency. Applying an appropriate tamping strategy helps reduce maintenance costs, making operations more cost-effective and leading to increased safety and passenger comfort levels. This paper discusses optimisation of the track geometry inspection interval with a view to minimising the total ballast maintenance costs per unit traffic load. The proposed model considers inspection time, the maintenance-planning horizon time after inspection and takes into account the costs associated with inspection, tamping and risk of accidents due to poor track quality. It draws on track geometry data from the iron ore line (Malmbanan) in northern Sweden, used by both passenger and freight trains, to find the probability distribution of geometry faults.
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| 6. |
- Beyglou, Ali, et al.
(författare)
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Adjusting Initiation Direction to Domains of Rock Mass Discontinuities in Aitik Open Pit Mine
- 2015
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Ingår i: 11th International Symposium on Rock Fragmentation by Blasting. - Carlton, Vic : The Australasian Institute of Mining and Metallurgy. - 9781925100327 ; , s. 385-391
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 7. |
- Beyglou, Ali, et al.
(författare)
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Face to Surface –Task 1 : Baseline Mapping of the Mining Operation in Aitik
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- “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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| 8. |
- Beyglou, Ali, 1986-
(författare)
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On the Operational Efficiency in Open Pit Mines
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 9. |
- Beyglou, Ali, et al.
(författare)
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Target fragmentation for efficient loading and crushing : The Aitik case
- 2017
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Ingår i: Journal of the Southern African Institute of Mining and Metallurgy. - : Southern African Institute of Mining. - 2225-6253 .- 2411-9717. ; 117:11, s. 1053-1062
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 10. |
- Danielsson, Markus, et al.
(författare)
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The Influence of Blast Fragmentation on Loadability in Sublevel Caving
- 2018
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Ingår i: Proceedings of the Forty-fourth Annual Conference on Explosives and Blasting Technique. - : International Society of Explosives Engineers.
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Konferensbidrag (refereegranskat)abstract
- 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.).
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