Rock engineering aspects of a modified mining sequence in a dip pillar layout at a deep gold mine

dc.contributor.authorJooste, Yvonne
dc.contributor.authorMalan, D.F. (Daniel Francois)
dc.date.accessioned2016-04-20T06:25:31Z
dc.date.available2016-04-20T06:25:31Z
dc.date.issued2015-10
dc.description.abstractScattered mining was practised on Kusasalethu Mine (previously Elandsrand Gold Mine) prior to 1998, but at deeper mining levels it was no longer feasible, since it would have resulted in unacceptably high stress levels and energy release rates. Longwall mining was not adopted at these depths as the mine required a more flexible mining method owing to the highly variable grade and the presence of geological structures. A mining method was developed that consisted of dip stabilizing pillars for regional support, as well as bracket pillars to clamp geological structures. A strict sequence of extraction was followed and this, together with the particular layout, was called the ‘sequential grid mining method’. This method addressed two key problems, namely negotiating adverse geology and the erratic grade of the Ventersdorp Contact Reef (VCR) orebody. However, a significant drop in production rates resulted in the need for alternatives and improvements to the original mine design. Modifications to the design were proposed in order to increase production rates, and an investigation to consider the rock engineering implications of these modifications was conducted. The study indicated that the modified method, called the ‘multi-raise mining method’, appears to be feasible and might address some of the production problems that were experienced with the original sequential grid design. An analysis of actual seismic data showed no significant differences between the original sequential grid mining and the implemented multi-raise mining. The numerical modelling of the mining layouts showed slightly higher interim energy release rates (ERRs) and average pillar stress (APS) levels during the extraction process. The final values are nevertheless identical to that of the original sequence. The study also investigated the use of a modelled moment method to analyse future seismic trends. The study illustrated that the expected seismic trends will be very similar for the multi-raise method compared to the original sequential grid mining method. This study is nevertheless considered of a preliminary nature and ongoing monitoring and analysis of seismic data at the mine is required to verify the response of the rock mass to the modified sequence and increased extraction rate. In particular, future work needs to investigate the effect of mining rate (advance rates in individual panels as well as volume of mining in particular raise lines) on the level of seismicity.en_ZA
dc.description.departmentMining Engineeringen_ZA
dc.description.librarianam2016en_ZA
dc.description.urihttp://www.saimm.co.za/journal-papersen_ZA
dc.identifier.citationJooste, Y & Malan, DF 2015, 'Rock engineering aspects of a modified mining sequence in a dip pillar layout at a deep gold mine', Journal of the Southern African Institute of Mining and Metallurgy, vol. 115, pp. 1097-1112.en_ZA
dc.identifier.issn0038-223X (print)
dc.identifier.issn2225-6253 (online)
dc.identifier.other10.17159/2411-9717/2015/v115n11a14
dc.identifier.urihttp://hdl.handle.net/2263/52066
dc.language.isoenen_ZA
dc.publisherSouthern African Institute of Mining and Metallurgyen_ZA
dc.rights© The Southern African Institute of Mining and Metallurgyen_ZA
dc.subjectDeep mine layouten_ZA
dc.subjectSequential grid miningen_ZA
dc.subjectSequence of extractionen_ZA
dc.subjectMining rateen_ZA
dc.subject.otherEngineering, built environment and information technology articles SDG-04
dc.subject.otherSDG-04: Quality education
dc.subject.otherEngineering, built environment and information technology articles SDG-08
dc.subject.otherSDG-08: Decent work and economic growth
dc.subject.otherEngineering, built environment and information technology articles SDG-09
dc.subject.otherSDG-09: Industry, innovation and infrastructure
dc.subject.otherEngineering, built environment and information technology articles SDG-11
dc.subject.otherSDG-11: Sustainable cities and communities
dc.subject.otherEngineering, built environment and information technology articles SDG-12
dc.subject.otherSDG-12: Responsible consumption and production
dc.titleRock engineering aspects of a modified mining sequence in a dip pillar layout at a deep gold mineen_ZA
dc.typeArticleen_ZA

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