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Schunnesson, Håkan
Publications (10 of 83) Show all publications
Schunnesson, H., Shekhar, G., Gustafson, A. & Johansson, D. (2019). A review of mining practices for surface support: an international survey. In: : . Paper presented at Ground Support 2019 (pp. 283-293). Sudbury, Canada
Open this publication in new window or tab >>A review of mining practices for surface support: an international survey
2019 (English)Conference paper, Published 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.

Place, publisher, year, edition, pages
Sudbury, Canada: , 2019
Keywords
surface support, mesh/screen installation, productivity, qualitative review, mine automation
National Category
Engineering and Technology Geotechnical Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-76799 (URN)978-0-9876389-4-6 (ISBN)
Conference
Ground Support 2019
Available from: 2019-11-21 Created: 2019-11-21 Last updated: 2019-11-21
Navarro, J., Schunnesson, H., Ghosh, R., Segarra, P., Johansson, D. & Sanchidrián, J. Á. (2019). Application of drill-monitoring for chargeability assessment in sublevel caving. International Journal of Rock Mechanics And Mining Sciences, 119, 180-192
Open this publication in new window or tab >>Application of drill-monitoring for chargeability assessment in sublevel caving
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2019 (English)In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 119, p. 180-192Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Rock mass condition, Underground blasting, Measurement while drilling (MWD), Block model, Explosives
National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-74969 (URN)10.1016/j.ijrmms.2019.03.026 (DOI)000472023100018 ()2-s2.0-85065716586 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-06-25 (johcin)

Available from: 2019-06-25 Created: 2019-06-25 Last updated: 2019-07-10Bibliographically approved
van Eldert, J., Schunnesson, H., Johansson, D. & Saiang, D. (2019). Application of Measurement While Drilling Technology to Predict Rock Mass Quality and Rock Support for Tunnelling. Rock Mechanics and Rock Engineering
Open this publication in new window or tab >>Application of Measurement While Drilling Technology to Predict Rock Mass Quality and Rock Support for Tunnelling
2019 (English)In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453XArticle in journal (Refereed) Epub ahead of print
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.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Measurement while drilling (MWD), Rock mass investigation, Tunnelling, Rock mass quality, Rock support, Drill and blast technology
National Category
Mineral and Mine Engineering Infrastructure Engineering Construction Management Geotechnical Engineering Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-76382 (URN)10.1007/s00603-019-01979-2 (DOI)000489294700001 ()
Funder
Rock Engineering Research Foundation (BeFo), 344
Available from: 2019-10-14 Created: 2019-10-14 Last updated: 2019-10-28
Shekhar, G., Gustafson, A., Hersinger, A., Jonsson, K. & Schunnesson, H. (2019). Development of a model for economic control of loading in sublevel caving mines. Mining Technology:Transactions of the Institutions of Mining and Metallurgy, 128(2), 118-128
Open this publication in new window or tab >>Development of a model for economic control of loading in sublevel caving mines
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2019 (English)In: Mining Technology:Transactions of the Institutions of Mining and Metallurgy, ISSN 2572-6668, Vol. 128, no 2, p. 118-128Article in journal (Refereed) Published
Abstract [en]

This paper presents an economic model for optimizing loading at the draw point in sublevel caving (SLC) operations. The input data consist of estimated bucket grades based on bucket weights from Load Haul Dump machines. This information, together with average operational mining costs, was used to create an economic model providing a real-time economic assessment of the draw point performance for SLC rings. The results demonstrate the importance of continuous draw point monitoring to optimize SLC operations. The proposed model provides an economic assessment of operating draw points and will help mine personnel to decide when to stop loading from a blasted ring. It can also help mine management understand the complexity of material flow in SLC operations. Finally, it provides operational flexibility for the mine to optimize loading at the draw point by increasing ore recovery while maintaining operational control of draw point performance.

Place, publisher, year, edition, pages
Taylor & Francis, 2019
Keywords
Draw control, mine economics, sublevel caving (SLC), draw point performance, Load Haul Dump (LHD)
National Category
Engineering and Technology Other Civil Engineering Business Administration
Research subject
Mining and Rock Engineering; Accounting and Control
Identifiers
urn:nbn:se:ltu:diva-73175 (URN)10.1080/25726668.2019.1586371 (DOI)000471557200005 ()2-s2.0-85064570087 (Scopus ID)
Funder
Vinnova, 1832144
Note

Validerad;2019;Nivå 2;2019-05-03 (johcin)

Available from: 2019-03-12 Created: 2019-03-12 Last updated: 2019-07-10Bibliographically approved
Ittner, H., Olsson, M., Johansson, D. & Schunnesson, H. (2019). Multivariate evaluation of blast damage from emulsion explosives in tunnels excavated in crystalline rock. Tunnelling and Underground Space Technology, 85, 331-339
Open this publication in new window or tab >>Multivariate evaluation of blast damage from emulsion explosives in tunnels excavated in crystalline rock
2019 (English)In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 85, p. 331-339Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Blasting, Blast damage, Emulsion explosives, Mechanized charging, Principal Component Analysis
National Category
Geotechnical Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-67454 (URN)10.1016/j.tust.2018.12.021 (DOI)000457512000031 ()2-s2.0-85059473074 (Scopus ID)
Funder
Rock Engineering Research Foundation (BeFo)
Note

Validerad;2019;Nivå 2;2019-01-10 (svasva)

Available from: 2018-02-01 Created: 2018-02-01 Last updated: 2019-04-23Bibliographically approved
Johansson, D., Nyberg, U., Stenman, U. & Schunnesson, H. (2019). Shock front curvature measurements of emulsion explosives. In: Roger Holmberg (Ed.), Proceedings of the 10th EFEE: . Paper presented at Helsinki Conference Proceedings 2019.
Open this publication in new window or tab >>Shock front curvature measurements of emulsion explosives
2019 (English)In: Proceedings of the 10th EFEE / [ed] Roger Holmberg, 2019Conference paper, Published 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 suggest a method 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 Ø25mm up to Ø65 mm i.e. from nearly critical diameters for a steady detonation up to diameters used in mining/quarrying and tunneling. The suggested methodology also introduce 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 analyze and evaluate the measurements is also proposed.

National Category
Mineral and Mine Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-76528 (URN)978-0-9550290-6-6 (ISBN)
Conference
Helsinki Conference Proceedings 2019
Available from: 2019-10-28 Created: 2019-10-28 Last updated: 2019-11-27
Ghosh, R., Gustafson, A. & Schunnesson, H. (2018). Development of a geological model for chargeability assessment of borehole using drill monitoring technique. International Journal of Rock Mechanics And Mining Sciences, 109, 9-18
Open this publication in new window or tab >>Development of a geological model for chargeability assessment of borehole using drill monitoring technique
2018 (English)In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 109, p. 9-18Article in journal (Refereed) Published
Abstract [en]

In the mining industry, the ability to charge and blast a production borehole is fundamental. However, if rock mass conditions are challenging, with cavities, fracture zones or even unstable boreholes, the charging crew may fail to insert the required amount of explosives, resulting in bad fragmentation and significant production disturbances in the downstream process. Prior detailed knowledge of the chargeability of each production fan or ring will improve both the planning and execution of the charging work in a mine. The paper describes a study using the drill monitoring technique to assess the chargeability of production boreholes. For the study, data were collected on four drill parameters, penetration rate, rotation pressure, feed pressure and percussive pressure, from 23 drill fans with a total of 186 boreholes. A parameter called fracturing was calculated based on penetration rate variability and rotation pressure variability. Sixty-three boreholes were filmed to establish different rock mass conditions: solid rock, cavities, fractured zones and cave-ins. Principal Component Analysis (PCA) was performed to model the relationship between drill monitoring data and the geological features. The developed model shows high potential by identifying charging problems directly from drill monitoring data, and has been verified and validated in a real charging operation in an operating mine.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-70266 (URN)10.1016/j.ijrmms.2018.06.015 (DOI)000440458000002 ()2-s2.0-85049528017 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-08-08 (andbra)

Available from: 2018-08-08 Created: 2018-08-08 Last updated: 2018-08-21Bibliographically approved
Shekhar, G., Gustafson, A., Boeg-Jensen, P., Malmgren, L. & Schunnesson, H. (2018). Draw control strategies in sublevel caving mines: A baseline mapping of LKAB's Malmberget and Kiirunavaara mines. The Southern African Journal of Mining and Metallurgy, 118(7), 723-733
Open this publication in new window or tab >>Draw control strategies in sublevel caving mines: A baseline mapping of LKAB's Malmberget and Kiirunavaara mines
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2018 (English)In: The Southern African Journal of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 1543-9518, Vol. 118, no 7, p. 723-733Article in journal (Refereed) Published
Abstract [en]

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

Place, publisher, year, edition, pages
The Southern African Institute of Mining and Metallurgy, 2018
Keywords
Sublevel caving, draw control, optimization, draw point monitoring
National Category
Engineering and Technology Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-71770 (URN)10.17159/2411-9717/2018/v118n7a6 (DOI)000442393900006 ()2-s2.0-85053623244 (Scopus ID)
Projects
SIP-STRIM
Funder
VINNOVA, 1832144
Note

Validerad;2018;Nivå 2;2018-12-07 (johcin)

Available from: 2018-11-27 Created: 2018-11-27 Last updated: 2018-12-07Bibliographically approved
Danielsson, M., Johansson, D. & Schunnesson, H. (2018). The Influence of Blast Fragmentation on Loadability in Sublevel Caving. In: Kevin Hachmeister (Ed.), Proceedings of the forty-forurth annual conference on explosives and blasting technique: . Paper presented at 44th Annual Conference on Explosives and Blasting Technique, San Antonio, Texas, Jan. 28–31 2018.
Open this publication in new window or tab >>The Influence of Blast Fragmentation on Loadability in Sublevel Caving
2018 (English)In: Proceedings of the forty-forurth annual conference on explosives and blasting technique / [ed] Kevin Hachmeister, 2018Conference paper, Published 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.).

National Category
Other Engineering and Technologies not elsewhere specified Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-70536 (URN)
Conference
44th Annual Conference on Explosives and Blasting Technique, San Antonio, Texas, Jan. 28–31 2018
Available from: 2018-08-22 Created: 2018-08-22 Last updated: 2018-08-28
Johansson, D. & Schunnesson, H. (Eds.). (2018). Twelfth International Symposium on Rock Fragmentation by Blasting: Fragblast 12. Paper presented at Twelfth International Symposium on Rock Fragmentation by Blasting; Luleå,Sweden on June 9-15, 2018. Luleå University of Technology
Open this publication in new window or tab >>Twelfth International Symposium on Rock Fragmentation by Blasting: Fragblast 12
2018 (English)Conference proceedings (editor) (Refereed)
Place, publisher, year, edition, pages
Luleå University of Technology, 2018
National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-68578 (URN)978-91-7790-134-1 (ISBN)978-91-7790-135-8 (ISBN)
Conference
Twelfth International Symposium on Rock Fragmentation by Blasting; Luleå,Sweden on June 9-15, 2018
Available from: 2018-05-02 Created: 2018-05-02 Last updated: 2019-05-28Bibliographically approved
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