The geotechnical evolution of deep level mechanised  destress mining at South Deep

Andrews, Peter; Butcher, Richard; Ekkerd, J.

doi:10.36487/acg_rep/1952_02_andrews

Cited by 4 publications

(2 citation statements)

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“…In order to apply these methods, a de-stress cut is extracted in a first phase, followed by large-scale stoping in the de-stressed ground in a second phase. An overview of the de-stressing techniques and their evolution in South Deep mine is given by Watson et al (2014) and Andrews et al (2019). Figure 3 outlines the stress reduction and effectivity of the de-stress cut schematically.…”

Section: Modern Raise Miningmentioning

confidence: 99%

Raise caving: a novel mining method for (deep) mass mining

Ladinig¹,

Wimmer²,

Wagner³

2022

Caving 2022: Fifth International Conference on Block and Sublevel Caving

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Raise caving is a novel mining method, which is based on the raise mining method. Raises are central and utilised for different purposes. Here only those directly related to the extraction of the orebody will be discussed. The main objective of raises is to utilise them for creating de-stressing slots, large drawbells and large stopes in an efficient manner. Remote-controlled or automated machinery is operated in raises. Further objectives of raises comprise monitoring and preconditioning. Depending on the field of application two different variants of raise caving can be distinguished, namely a de-stressing variant and a block caving variant.In the de-stressing variant, narrow slots are created first with the objective of providing stress shadows for mining activities in the subsequent production phase. Creating the slots in the de-stressing phase is high stress mining. Hence, massive pillars are left between slots to control the stress situation for de-stress raise development and mining-induced seismicity. After the de-stressing phase is completed, large-scale mineral extraction commences in de-stressed zones. In the production phase large drawbells are developed from raises and large stopes are extracted. During stope blasting only the swell of each blast is mucked so that blasted rock mass provides temporary support to the stope walls. After blasting is completed, the stope is drawn empty and the hanging wall is allowed to cave and caved hanging wall rock mass fills up the stope successively. The massive pillars are extracted in the course of large-scale stoping in the production phase too.In the block caving, variant raises are utilised for drawbell development, undercutting, preconditioning and monitoring purposes. Large drawbells are developed from raises. As drawbells are developed in upward direction, the roof area of the drawbells is enlarged constantly until continuous caving is initiated. Due to the integration of several key activities the block caving variant of raise caving is also referred to as integrated raise caving. This paper highlights the background and motivation for raise caving and it describes both raise caving variants. Steps for the implementation of the methods are outlined and advantages of the individual methods are outlined briefly. Key issues for the implementation of raise caving are highlighted and discussed, and an outlook on currently ongoing research and development activities, which include in situ tests of the method and machinery, is provided. Dedicated accompanying papers provide more information on the ongoing research and development.

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Section: Modern Raise Miningmentioning

confidence: 99%

Raise caving: a novel mining method for (deep) mass mining

Ladinig¹,

Wimmer²,

Wagner³

2022

Caving 2022: Fifth International Conference on Block and Sublevel Caving

View full text Add to dashboard Cite

show abstract

“…These layouts and sequence and the non-mechanised mining technology are generally not comparable to and applicable in raise caving. An exception is South Deep mine, where a reef package is mined with large-scale stoping methods, which are applied in parts of the deposit that were de-stressed before by horizontal de-stress cuts; compare Watson et al (2014) and Andrews et al (2019). The utilised layouts and sequences of South Deep mine come closest to raise caving.…”

Section: Experience From and Site Visits At Other Minesmentioning

confidence: 99%

Test mining with raise caving mining method: one-time chance to prove the concept?

Karlsson¹,

Ladinig²,

Grynienko³

2022

Caving 2022: Fifth International Conference on Block and Sublevel Caving

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Raise caving is a novel mining method, which is based on the raise mining method. Raises play a central role in the method and are utilised for different purposes. In the de-stressing variant, raise caving, the de-stressing slots are created first in a so-called de-stressing phase. The de-stressing slots have a tabular shape, and their objective is to provide stress shadows for mining activities in the subsequent production phase.To prove the concept and provide input parameters for a feasibility level evaluation, a limited scale trial is required.Located at the depth of LKAB's Kiruna mine in Sweden (a +25 Mtpa underground, sublevel caving (SLC) iron ore mine), the raise caving test site will be constructed in deeper parts of the mine, in an area partially prepared for SLC but mining not yet initiated. Geotechnical investigations and numerical modelling preceding development work are underway with first de-stressing raise scheduled for early 2023. Mining activities and consequent preliminary method evaluations are due during 2023-2024 with the final, a feasibility level, study to be completed by the end of 2025.The site selection process focused on locating a site that is, in key aspects, comparable with the future mining environment in the deeper parts of the mine. These are rock stress (direction and magnitude), geology and geotechnical properties. Additional aspects assessed were absence of major weakness zones, minimised negative impact for mine's performance and life-of-mine (LOMP), and relatively rapid execution of the test site construction. Both Malmberget and Kiruna mines were considered as potential sites.During the extraction of the pillar at the test site, the behaviour and condition of the pillar is continuously monitored. Other aspects to be evaluated are the feasibility to work in high stress environments during de-stressing slot development (tunnelling, raiseboring, longhole drilling), during mucking waste rock dilution entry, ore flow and ore recovery rate from a single-level mucking location.When proven successful, the raise caving can contribute to a safe and cost-effective alternative mining method in high stress environments. This paper describes steps taken in selection of a test site and integration with mine production activities.

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Raise Caving—A Hybrid Mining Method Addressing Current Deep Cave Mining Challenges

Ladinig

Wagner

Karlsson

et al. 2022

Berg Huettenmaenn Monatsh

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Cave mining progresses to depths exceeding 1000 m and ore bodies situated in competent and strong rock masses are nowadays extracted by different cave mining methods. Widely applied caving methods in massive deposits are block and panel caving, inclined caving, and sublevel caving. All caving methods have in common that rock mass caves during extraction of an ore body in a controlled way. As a result, regional stress changes occur, considerable abutment stresses form, and large-scale subsidence and significant seismic energy releases occur. Experience shows that these rock mechanics effects become especially critical at great depths, where primary stress magnitudes reach and exceed rock mass strength, as well as in strong competent rock masses, which require large footprints to enable continuous caving. The presented raise caving method addresses previously mentioned rock mechanics issues. Initially, de-stressing slots are developed from raises with a minimum amount of pre-development. Substantial pillars separate neighboring slots in order to control stress magnitudes and seismicity near slots. The slots provide a stress shadow for production infrastructure so that large-scale mineral extraction can take place in de-stressed ground. As mining progresses, pillars are extracted and hanging wall is allowed to cave. Results of a pre-study conducted together with LKAB have highlighted advantages of raise caving from a rock mechanics, safety, and cost point of view.

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The geotechnical evolution of deep level mechanised destress mining at South Deep

Cited by 4 publications

References 0 publications

Raise caving: a novel mining method for (deep) mass mining

Raise caving: a novel mining method for (deep) mass mining

Test mining with raise caving mining method: one-time chance to prove the concept?

Raise Caving—A Hybrid Mining Method Addressing Current Deep Cave Mining Challenges

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