Features of flow of broken rock in extraction of ores with sublevel caving

Stazhevskii, S. B.

doi:10.1007/bf02046162

Cited by 17 publications

(9 citation statements)

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“…Furthermore, fragmentation of the ore by blasting assumes that fragments are created through the tensile failure in rock material, and the surfaces of such fragments are very rough. Blasted ore fragmentation is identified as one of the main influencing parameters on gravity flow formation since early observations were made [2][3][4]. Furthermore, novel computer applications confirm that blasting has a large influence on the production outcome [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…Since it is the idealization of the gravity flow, many problems with this approach were recognized through a variety of experiments [3,8]. Other modeling approaches include stochastic methods [13,14], cellular automata [15,16], small-scale [4,7,17,18] and full-scale [8,10,[19][20][21][22] experiments, but also some modifications of caving methods are considered [23][24][25]. When it comes to the full-scale in situ experiments, it is hard to distinguish between the partial influences of some parameters, since all of them are incorporated with the results.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Investigation of Caved Rock Mass Friction and Fragmentation Change Influence on Gravity Flow Formation in Sublevel Caving

Lapčević

Torbica

2017

Minerals

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Abstract:Metal grade dilution is the main production disadvantage of the sublevel caving method, and overcoming this problem has been investigated over the years using different methodologies. Herein, numerical simulation using the discrete element method is used to analyze the influence of friction and fragmentation change in caved rock mass on ore dilution and recovery. The individual and mutual change of each parameter is analyzed. It is considered that at the beginning, the friction angle can be lower or higher than the basic friction angle, and after a certain moment, it will come close to the basic friction value, while fragmentation always decreases. The results showed that both friction and fragmentation, when decreasing, are influencing the higher dilution due to smaller kinematic resistance in the caved mass. If lower friction than the basic one is considered, with the drop of fragmentation, the decrease of dilution occurs. Once the basic friction angle is reached, the fragmentation of the caved mass becomes the dominant influencing factor, and its decrease will continuously increase the dilution until the end of production. However, identifying periods when these changes occur, the possibility for better production planning opens at the design stage, as well as the application of different sublevel designs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Caved Rock Mass Friction and Fragmentation Change Influence on Gravity Flow Formation in Sublevel Caving

Lapčević

Torbica

2017

Minerals

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“…Scale models have been used to simulate the impacts of large rocks and disruption to uniform flow typically observed in sand and gravel experiments. Stazhevskii (1996) used larger rocks in model experiments to measure the effect on flow behaviour and how the presence of oversize in operating mines can result in disturbed flow conditions. An example from the experiment is shown in Figure 6.…”

Section: Physical Modelsmentioning

confidence: 99%

Recovery and flow in cave mining: current knowledge gaps and the role of technology in the future

Campbell¹

2020

Proceedings of the Second International Conference on Underground Mining Technology

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Gravity flow of granular material in a caving mine is complex. Ore recovery and cave flow is impacted by wide particle size distributions, particle interlocking, an evolving cave geometry, and the mine draw strategy. However, these factors are rarely quantified in forecasts of cave performance at key stages in the planning process. Reliable tools for simulating cave flow and the technology to measure cave flow and footprint deformation have only emerged in the last 10 years. This includes technology such as electronic cave markers and tracker systems, 3D laser scanning for tunnel deformation and fragmentation measurement as well as coupled cave flow-deformation numerical simulations. This paper provides an overview of how the current state of cave flow knowledge has evolved and the knowledge gaps that still exist. The impact of these knowledge gaps is described in context with mine design and current design guidelines. A series of experiments to address these knowledge gaps have been conceptualised for future trials in existing and future caving mines. A methodology including instrumentation, monitoring requirements and operational practices is outlined for each experiment.

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“…Small-scale experiments have been conducted to simulate gravity flow in SLC mines and to measure the effect of different variables on gravity flow (Free 1970;Janelid & Kvapil 1966;McCormick 1968;Panczakiewicz 1977;Peters 1984;Stazhevskii 1996). These experiments provide valuable insight into gravity flow behaviour, including the effects of particle size, overburden confinement, blast ring angle and crosscut dimensions.…”

Section: Introductionmentioning

confidence: 99%

Effects of blast ring burden and explosive density on fragmentation and ore recovery in sublevel cave mines

Campbell¹

2018

Proceedings of the Fourth International Symposium on Block and Sublevel Caving

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Numerous studies have proved that blast design impacts gravity flow in sublevel cave mines. However, such designs are yet to be fully optimised owing to the small number of mines with published full-scale experimental studies specifically planned to measure the effect of blast design variables on fragmentation and recovery. This paper details the results of a three-year experimental program undertaken at the Ernest Henry sublevel cave mine. The program consisted of 162 production blast rings conducted over six experimental trials to quantify the impact of ring burden, explosive density and crosscut height on gravity flow and recovery. The results of the research program are split between this paper and another entitled 'Full-scale experiments to measure the effect of crosscut height on recovery in sublevel cave mines' (Campbell 2018). The impact of ring burden and explosive density on fragmentation and recovery was quantified using full-scale experiments. Electronic cave markers were used to measure recovery over multiple sublevels and the extraction zone evolution in real time. Fragmentation was measured during loading since the size of the fragmented rock is known to affect gravity flow behaviour and ore recovery in sublevel cave mines. The size distribution of the fragmented rock from blasting was measured using high-resolution 3D laser scanning technology. Results of the experimental programs prove that ring burden and explosive density have a significant impact on ore recovery. Cumulative secondary recovery was between 8 and 10% higher on average for the reduced explosive density and increased ring burden trials compared with the baseline measurements. The effect of blast design variables on fragmentation was found to be less than expected. The experimental outcomes differ from earlier theories and the research hypotheses, which predicted the opposite effect on recovery for changes in ring burden and explosive density. Underground observations and detailed analysis are used to explain the results. Although the results are affected by the mine design and rock mass conditions at the mine and therefore site-specific, the findings on the relative impact of design variables on fragmentation and recovery are potentially transferable to other sublevel cave (SLC) mines. Additional site-specific testing is required to confirm the impact of design variables in different conditions and is recommended prior to selecting or altering blast design parameters.

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Features of flow of broken rock in extraction of ores with sublevel caving

Cited by 17 publications

References 0 publications

Numerical Investigation of Caved Rock Mass Friction and Fragmentation Change Influence on Gravity Flow Formation in Sublevel Caving

Numerical Investigation of Caved Rock Mass Friction and Fragmentation Change Influence on Gravity Flow Formation in Sublevel Caving

Recovery and flow in cave mining: current knowledge gaps and the role of technology in the future

Effects of blast ring burden and explosive density on fragmentation and ore recovery in sublevel cave mines

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