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Assessment of rock mass quality and its effects on charge ability using drill monitoring technique
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. (Mining and Rock Engineering)ORCID iD: 0000-0001-9108-9386
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

For an efficient mining operation, it is essential to have as much information as possible aboutthe ore to be excavated and the rock masses surrounding the ore. Geological information andthe content and distribution of extractable minerals, are central concerns for long term mineplanning. However, for mine stability and production scheduling, the mechanical conditionsof ore and side rock are also very important. The underground mining process normallyconsists of a number of unit operations, such as drilling, charging, blasting, loading,transportation, hoisting etc., linked in a production chain. The quality of the initial operations(drilling, charging and blasting) normally defines the pre-conditions for the following loadingand transportation processes in the mine. The ability to fully charge holes as planned has beenidentified as one of the major obstacles for smooth fragmentation. Course or unevenfragmentation will, for example, significantly affect the loading and transportation efficiencyin the downstream production chain.Earlier studies in LKAB’s Malmberget mine have shown that the chargeability is on averagearound 90%. However, individual levels can have an average chargeability of only 70% andindividual rings, at those levels, can suffer from chargeability as low as 50%. A significantpart of these problems has its origin in geo-mechanical problems in the rock mass. Therefore,detailed knowledge of the rock mass condition surrounding the boreholes is essential toimprove the planning and execution of the charging works in a mine and to improve overallfragmentation and production efficiency.The focus of this thesis is therefore to define and evaluate geo-mechanical features in thedrilled rock mass effecting chargeability, and to evaluate drill monitoring technique for theassessment of rock mass quality and its effects on borehole’s chargeability using hydraulic In-The-Hole (ITH) percussive drilling.The research is based on literature review, drill-monitoring data, borehole filming, on-lineproduction database and monitoring of charging operation. Statistical methods are used toanalyse drill data. The data have been collected from LKAB’s underground mine inMalmberget, Sweden.Several rock mass conditions including caving, shearing, deformation, fracturing, cavities,solid rock, etc., have been identified during filming of 361 production boreholes.Measurement While Drilling (MWD) technique has been used to assess the quality of thepenetrated rock mass. In order to do so, a detailed analysis of the drilling system and thedrilling control including how monitored parameters relate to each other and to the penetratedrock mass conditions, has been performed. The results show that the MWD data containpronounced hole length dependent trends, both linear and step-wise linear, for mostparameters. By combining the borehole filming and the analyses of monitored drillparameters, the drilling responds to each geo-mechanical features in the rock mass is furtherdemonstrated. High correlation has been found between the geo-mechanical rock properties(fractures, cavities, solid rocks, etc.,), and the registered drilling system’s response. Theanalyses show that the responses from the drill monitoring system can distinguish between solid rock, fracture zone, cavity and cave-in. Based on the correlation between the registereddrilling system’s responses and the geo-mechanical features, a geo-mechanical model isdeveloped to assess the borehole chargeability. Principal Component Analysis (PCA) isperformed to model this relationship. The developed model can distinguish fans, or parts offans, with solid, non-fractured rocks where no chargeability problems can be expected, fromfans, or part of fans, with fractures, cavities or cave-in risks, where chargeability problemscan be expected. The model shows high potential for identifying charging problems in theborehole, and has been verified and validated by following an actual charging operation in thereal production environment.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2017. , p. 70
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords [en]
Underground mining, Sublevel caving, Rock mass quality, Borehole filming, Borehole quality, Borehole stability, Borehole instability, Drill monitoring technique, Measurement While Drilling (MWD), Hydraulic in-the-hole (ITH) drilling, Drill system behaviour, Principal Component Analysis (PCA), Geo-mechanical model, Chargeability, Fracture zone, Shear zone, Cave-in, Cavity, Rock blasting
National Category
Mineral and Mine Engineering Geotechnical Engineering
Research subject
Mining and Rock Engineering
Identifiers
URN: urn:nbn:se:ltu:diva-65584ISBN: 978-91-7583-963-9 (print)ISBN: 978-91-7583-964-6 (electronic)OAI: oai:DiVA.org:ltu-65584DiVA, id: diva2:1140280
Public defence
2017-11-08, F1031, Luleå University of Technology, Luleå, 10:00 (English)
Opponent
Supervisors
Available from: 2017-09-12 Created: 2017-09-11 Last updated: 2018-06-12Bibliographically approved
List of papers
1. Borehole instability in Malmberget Underground Mine
Open this publication in new window or tab >>Borehole instability in Malmberget Underground Mine
2015 (English)In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 48, no 4, p. 1731-1736Article in journal (Refereed) Published
National Category
Other Civil Engineering
Research subject
Operation and Maintenance; Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-6528 (URN)10.1007/s00603-014-0638-1 (DOI)000356884500030 ()2-s2.0-84933182948 (Scopus ID)4c09e7c7-19d4-4a51-85cb-e9eabc199620 (Local ID)4c09e7c7-19d4-4a51-85cb-e9eabc199620 (Archive number)4c09e7c7-19d4-4a51-85cb-e9eabc199620 (OAI)
Note
Validerad; 2015; Nivå 2; 20131230 (rajgho)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
2. Monitoring of Drill System Behavior for Water-Powered in-the-hole (ITH) drilling
Open this publication in new window or tab >>Monitoring of Drill System Behavior for Water-Powered in-the-hole (ITH) drilling
2017 (English)In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 7, no 7, article id 121Article in journal (Refereed) Published
Abstract [en]

A detailed understanding of the drilling system and the drilling control is required to correctly interpret rock mass conditions based on monitored drilling data. This paper analyses data from hydraulic in-the-hole (ITH) drills used in LKAB’s Malmberget mine in Sweden. Drill parameters, including penetration rate, percussive pressure, feed pressure, and rotation pressure, are monitored in underground production holes. Calculated parameters, penetration rate variability, rotation pressure variability, and fracturing are included in the analysis to improve the opportunity to predict rock mass conditions. Principal component analysis (PCA) is used to address non-linearity and variable interactions. The results show that the data contain pronounced hole length-dependent trends, both linear and step-wise linear, for most parameters. It is also suggested that monitoring can be an efficient way to optimize target values for drill parameters, as demonstrated for feed force. Finally, principal component analysis can be used to transfer a number of drill parameters into single components with a more straightforward geomechanical meaning

Place, publisher, year, edition, pages
Basel: MDPI, 2017
National Category
Mineral and Mine Engineering Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-63802 (URN)10.3390/min7070121 (DOI)000407363800015 ()2-s2.0-85026226267 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-08-15 (andbra)

Available from: 2017-06-08 Created: 2017-06-08 Last updated: 2018-11-26Bibliographically approved
3. Assessment of rock mass quality using drill monitoring technique of Hydraulic ITH drills
Open this publication in new window or tab >>Assessment of rock mass quality using drill monitoring technique of Hydraulic ITH drills
Show others...
2017 (English)In: International Journal of Mining and Mineral Engineering, ISSN 1754-890X, Vol. 8, no 3, p. 169-186Article in journal (Refereed) Published
Abstract [en]

A rock drilling system always responds to variations in the mechanical properties of the penetrated rock mass. Combining the drill response with a detailed understanding of the drill system has the potential to give a detailed and high-resolution characterisation of the penetrated rock mass along the borehole. This paper analyses 186 boreholes, drilled using a water powered in-the-hole (ITH) drilling technique considering drill parameters; penetration rate, rotation pressure, feed pressure and percussive pressure. In addition, it suggests, calculates and uses a parameter reflecting rock fracturing. Sixty-three of the holes were filmed with a borehole camera to reveal the geo-mechanical features. The results show that the responses from the drill monitoring system can distinguish between solid rock, fracture zones, cavities and damaged rock. The ability to extract this information directly from the drilling operation provides unique prior information and can be useful to adjust production planning before charging and blasting boreholes.

Place, publisher, year, edition, pages
InderScience Publishers, 2017
National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-14546 (URN)10.1504/IJMME.2017.10006862 (DOI)2-s2.0-85027419669 (Scopus ID)deb3ea8d-3a3b-4f92-a89c-67863f4661bf (Local ID)deb3ea8d-3a3b-4f92-a89c-67863f4661bf (Archive number)deb3ea8d-3a3b-4f92-a89c-67863f4661bf (OAI)
Note

Validerad;2017;Nivå 1;2017-08-16 (rokbeg)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-11-20Bibliographically approved
4. Development of a geo-mechanical model for chargeability assessment of borehole using drill monitoring technique
Open this publication in new window or tab >>Development of a geo-mechanical model for chargeability assessment of borehole using drill monitoring technique
(English)In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545Article in journal, Editorial material (Refereed) Submitted
National Category
Engineering and Technology
Identifiers
urn:nbn:se:ltu:diva-65481 (URN)
Available from: 2017-09-04 Created: 2017-09-04 Last updated: 2018-06-12

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