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Mine pillar structures
Published in M.L. Jeremic, Ground Mechanics in Hard Rock Mining, 2020
Pillars in purely elastic rocks can be divided into four principal mining method related classes. Square and rectangular pillars are an integral part of room-and-pillar mining. Design is based on uniaxial stresses from superincumbent loading as is done for the design of coal pillars in room-and-pillar operations.Long pillars are an integral part of slot mining, a variant of room-and-pillar mining used in gently dipping ore bodies.Irregular pillars were common to old mining methods such as breast stoping. The pillars were randomly spaced and their design followed the principles used in the design of square and rectangular pillars for room-and-pillar operations.Rib and crown pillars are elongated structures in both open and filled stoping operations in steeply dipping ore bodies. Design may have to take into account biaxial loading.
Nonrenewable Energy Resources
Published in Julie Kerr, Introduction to Energy and Climate, 2017
Oil shale can be mined using one of two methods: underground mining using the room-and-pillar method or surface mining. Room and pillar mining is a system in which the mined material is extracted across a horizontal plane, creating horizontal arrays of rooms and pillars. The pillars support the ceiling and the material is extracted from the “room.” After mining, the oil shale is transported to a facility for retorting, a heating process that separates the oil fractions of oil shale from the mineral fraction. The vessel in which retorting takes place is known as a retort. After retorting, the oil must be upgraded by further processing before it can be sent to a refinery, and the spent shale must be disposed of. Spent shale may be disposed of in surface impoundments, or as fill in graded areas; it may also be disposed of in previously mined areas. Eventually, the mined land needs to be reclaimed.
Coal
Published in Peter M. Schwarz, Energy Economics, 2023
Underground mining is still the predominant form of mining in developing countries, as well as in developed countries where coal seams are deep. One technique is room-and-pillar that may be followed by a final stage of retreat mining. Room and pillar mining builds rooms into the coal mine, leaving pillars to support the roof. To maximize profit, the rooms and especially the pillars must be of optimum size. Pillars are left-behind resources, so larger pillars leave behind more resources. However, smaller pillars increase the chance of a mine collapse. Retreat mining removes the coal pillars to get the remaining coal, increasing the danger that the mine roof could collapse.
Analysis of surface subsidence due to longwall mining under weak geological conditions: Turgut basin of Yatağan-Muğla (Turkey) case study
Published in International Journal of Mining, Reclamation and Environment, 2019
The overburden above an underground mine, such as longwall coal mine will induce caving, displacement of the overburden material owing to the weight of the ground above the undeground mine and will usually result in measurable movement, or subsidence, at the ground surface above the mine. The shape of the disturbed ground surface above a collapsed mine is called a subsidence. In this work, the term ‘subsidence’ refers only to the vertical displacement of the ground surface. In numerical analyses, although small amount of horizontal movement was observed, it was not treated as significant as to impact on the structure of the pipline system and was neglected. treated elsewhere. Subsidence above coal mines can be more accurately predicted where longwall mining has occurred as opposed to room-and-pillar mining, because it is more reasonable to assume that the mined cavities will collapse within a short time after mining activity has ceased.
Size-dependent compressive strength properties of hard rocks and rock-like cementitious brittle materials
Published in Geosystem Engineering, 2019
Mohammad Darbor, Lohrasb Faramarzi, Mostafa Sharifzadeh
In rock engineering, the effect of scale on the strength and deformation properties of a rock mass is one of the most important issues. Dependence of the compressive strength on the specimen size plays a fundamental role in designing rock structures. One example relates to the room and pillar mining method, which relies on the strength of pillars to support underground openings. However, pillar sizes and thus their strengths can vary significantly (Masoumi, Douglas, & Russell, 2016). Laboratory strength measurements made on small samples are to be corrected so that they can be suitably applied to the design of larger rock structures. Previous studies have shown that uniaxial compressive strength (UCS) of intact rock decreases as specimen size increases. However, its variations depend on a number of parameters such as the type of rock, mineralogical composition and porosity (Poulsen & Adhikary, 2013; Yoshinaka, Osada, Park, Sasaki, & Sasaki, 2008). It eventually becomes difficult to determine the strength characteristics of actual-scaled samples from equipment cost and loading capacity perspectives. Therefore, it is worth estimating the strength characteristics of actual scale intact rock using laboratory tests and specimen size effect models (Bazant, 1997; Bazant & ASCE, 1984; Carpinteri, Chiaia, & Ferro, 1995; Hoek & Brown, 1980; Masoumi, Saydam, & Hagan, 2015; Weibull, 1951).
Production key figures for planning the mining of manganese nodules
Published in Marine Georesources & Geotechnology, 2018
Sebastian Ernst Volkmann, Felix Lehnen
The extraction efficiency or extraction ratio is an established term in mining, which is commonly used in room-and-pillar mining (Darling 2011). Room-and-pillar mining is an underground mining method, which is usually used for flat-lying deposits. The material is extracted across a horizontal plane, whereby pillars are left in place to support the roof. SMnN can be considered as a thin layer of ore covering vast areas of seafloor. Although, the reasons for not mining valuable material are different, deep-sea strip mining and terrestrial room-and-pillar mining have in common that mine design has effect on extraction efficiency. In SMnN mining, the extraction efficiency is defined to be the ratio of the quantity of SMnN mined to the reserve. Cherry picking only nodule-rich parts of a mine site could result in poor mining efficiency but sufficient (higher) extraction efficiency at the same time. For the exemplary area, extraction efficiency was estimated to be 30–50%, while the overall mining efficiency was computed to be 40% at the best. However, the difference is insignificant in case the mineable area is utilized most efficiently.