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Underground hard rock (metal/non-metal) mining
Published in A.J.S. (Sam) Spearing, Liqiang Ma, Cong-An Ma, Mine Design, Planning and Sustainable Exploitation in the Digital Age, 2023
A.J.S. (Sam) Spearing, Liqiang Ma, Cong-An Ma
Sub-level stoping (illustrated in Figures 3.49 and 3.50) is used for mining mineral deposits with steep orebodies and fairly regular boundaries, stable hangingwall and footwall and competent orebody. This method requires extensive orebody development with relatively high capital expenditures, but production costs are comparatively low because most of the development is in ore. The thickness of the deposit between the hangingwall and footwall usually varies from a few meters to tens of meters wide. In this method, mining starts at the bottom of a level and proceeds upward. The orebody is vertically divided into levels, and between two levels, the stopes of convenient size are formed, hence the name sub-level stoping. Leaving a crown pillar at the top of the stope safeguards the level above, while lower level is utilized as haulage level to collect the mineralization from the stopes. The level developments, commonly in the footwall, range from 50m to 150m, based on the vertical extent of the orebody and the number of production openings that can be extracted at each level. Rib pillars are often left between the stopes on the same elevation. Between the main levels, ramps are usually driven for access and transportation. These ramps also give access to the sub-levels, which are developed at regular intervals to remove blocks of ore. Dilution with waste rock can occur if ore boundaries are irregular or if caving occurs, but usually almost all of the ore in the stope is recovered.
Geomechanical safety aspects in hard rocks mining based on room-and-pillar and longwall mining systems
Published in Ferri Hassani, Jan Palarski, Violetta Sokoła-Szewioła, Grzegorz Strozik, Minefill 2020-2021, 2021
Witold Pytel, Bogumila Palac-Walko, Piotr Mertuszka
Room-and-pillar mining system (Figure 1b)is based on one- or two-phase almost complete extraction approach with the first phase creating elastic pillars after driving rooms, while during the second phase these pillars are mined out on the retreat. The room-and-pillar mining method is a type of open stoping used in near horizontal deposits in reasonably competent rock, where the roof is supported primarily by pillars and, depending on the roof conditions, by rock bolts or other types of support. The ore is excavated as rectangular shaped rooms or entries in the ore body seam, leaving parts of the ore between the entries as remnant pillars to support the hanging wall or immediate roof strata.
The Other Energy Sources
Published in Anco S. Blazev, Power Generation and the Environment, 2021
The “cut and fill” or open stoping method used today consists of removal of the ore and refilling the space left behind with waste rock, sand and cement. The “shrinkage” method is used when sufficient broken ore is removed via the chutes below to allow miners working from the top of the pile to drill and blast the next layer to be broken off. This eventually leaves a large hole in the mine body.
Stability analysis of crown pillar under the zone of relaxation around sub-level open stopes using numerical modelling
Published in Geomatics, Natural Hazards and Risk, 2023
Vishal Babu Guggari, Hemant Kumar, Gnananandh Budi
Sublevel stoping is a mining method commonly used to extract massive and tabular deposits with steep dips. This method has been proven to be highly productive and cost-effective for extracting various types of ore bodies (Rao Islavath and Deb 2018). Large diameter blasthole (LDBH) stoping is a type of sub-level stoping used when large-scale production is required. For a width of 20–25 m, the height of the stope may exceed 75 m. Once these stopes are extracted, they leave a void space known as a stope. To ensure the stability of such a stope, horizontal pillars, also known as crown pillars, are left intact (Mohanto and Deb 2020). These pillars serve as the primary support for the stopes while they are being excavated. The size of the crown pillars is critical, as oversized pillars can result in a loss of reserves, while undersized pillars can lead to instability and failure within the mine.
Stochastic stope design optimisation under grade uncertainty and dynamic development costs
Published in International Journal of Mining, Reclamation and Environment, 2022
Matheus Furtado e Faria, Roussos Dimitrakopoulos, Cláudio Pinto
The sublevel open stoping is a self-supported and non-entry underground mining method, presenting some degree of selectivity and flexibility, in which the orebody is vertically split into production levels that are often separated by horizontal pillars. Within the primary levels, stopes are usually delimited by rib and longitudinal pillars, while regularly spaced blasting drifts are developed, defining the sublevels (Figure 1). The stopes remain empty during their exploitation with eventual post-backfilling [15–18]. Some three-dimensional sublevel stoping design optimisation methods have been proposed, which incorporate progressively different geotechnical and operational aspects. The Floating Stope algorithm [19] and the Maximum Value Neighbourhood algorithm [20] float a fixed minimum stope size on the input orebody model and define profitable envelopes in which the stopes should be further manually designed. A predefined cut-off grade or the economic value of a block’s neighbourhood is the respective criteria used to build the profitable boundaries in those methods. Topal and Sens [1] and Sandanayake et al. [21,22] present different methods to select non-overlapping stopes with variable sizes to define a stope layout with unified stopes. Furthermore, Sandanayake et al. [21,22] integrate more operational constraints, such as pillar requirements and level allocation.
Integrated underground mining and pre-concentration systems; a critical review of technical concepts and developments
Published in International Journal of Mining, Reclamation and Environment, 2021
Farzad Sotoudeh, Micah Nehring, Mehmet Kizil, Peter Knights
Sublevel stoping is one of the most common and large scale mining methods, which can be implemented in tabular and steeply dipping orebodies by creating large open stopes in a vertical direction. This method is appropriate for deposits with competent ore and host rock [57]. The ore is broken by drilling and blasting in sublevels within stopes, and the fragmented ore is mucked from drawpoints using LHDs. The sequence and extraction of stopes is a critical issue in this method which requires precise planning and design over the mine life. This is due to the consideration of stability in adjacent stopes and fillmasses [58]. Dilution in this mining method can be high in irregular deposits particularly where the rock in the wall is less competent. Even though the most important benefits of this method are high productivity and efficiency, lower costs and reasonably high recovery, a high level of dilution in inauspicious conditions can occur.