Long-term stability of a backfilled room-and-pillar test section at the Buick Mine, Missouri, USA

The stability and productivity concerning a modification on the traditional room and pillar for a new selective technique at the Portuguese Panasqueira Mine have been described. The traditional room-and-pillar stoping uses 5.0-m wide rooms with 3.0 m3.0 m pillars, while the selective room-and-pillar mining technique consists in stoping with rooms of 4.0 m wide and pillars of 4 m4 m with a subsequent selective cutting of the quartz veins at the mid pillar of approximately 0.5 m high, to obtain a pillar section with an area of 3.0 m3.0 m. The stability and productivity analyses indicate that the selective technique obtains smaller average pillar safety factor, more rock mass displacement, more extraction and selectivity ratios, and ore grade improvement, compared with the traditional technique. These results show that the selective technique is also more convenient. This proposed selective room-and-pillar mining technique is applicable to any sub-horizontal narrow quartz veins with wolfram, gold, etc. such as the famous La Rinconada gold mine in the Peruvian Andes.

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“…8), revealing that they are very similar, and this is an important indicator for validating the used modelling method [13][14][15].…”

Section: Discussion On the Stability And Production Indicatorsmentioning

confidence: 99%

Comparative stability analyses of traditional and selective room-and-pillar mining techniques for sub-horizontal tungsten veins

Torres

Gama

Silva

et al. 2011

Int J Miner Metall Mater

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“…e consolidation process of CGFACPB occurs in the complicated underground curing and stress environment. Under the high overlying strata stress, CGFACPB material could collapse or experience an excessive deformation, which could not only affect the mining operations but also cause the serious damages to surface villages [3][4][5][6]. CPB is a widely used backfilling method in mining that can significantly improve stope stability in the metal mines or reduce the surface subsidence in the underground coal mines [1,7].…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Mechanical Properties of In Situ Cemented Paste Backfill Containing Coal Gangue and Fly Ash

Zhuang

Zhang

2020

Advances in Civil Engineering

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Cemented paste backfill containing coal gangue and fly ash (CGFACPB) is an emerging backfill technique for coal mines that allows environmentally hazardous coal gangue and fly ash to be reused in the underground goaf. Meanwhile, CGFACPB can provide an efficient ground support and reduce the surface subsidence. Due to the difference of consolidation environment between the laboratory and the field, the mechanical properties of the cemented paste backfill vary significantly. In this paper, the core specimens were collected from an underground coal mine where the CGFACPB was used for coal mining, and the mechanical properties of the collected specimens were investigated. The cores were obtained from the underground coal mine, and then the standard cylinders or discs were prepared in laboratory. The uniaxial compressive strength (UCS), Young’s modulus, and Poisson’s ratio were determined by the compression tests, and the tensile strength was achieved by the Brazilian test. Then the internal friction angle and cohesion were calculated using the improved Mohr–Coulomb strength criterion. The results showed the development of UCS can be divided into four stages, and the final long-term stable value was about 5.1 MPa. The development of Young’s modulus had similar trend. Young’s modulus had a range from 550 MPa to 750 MPa and the mean value of 675 MPa. Poisson’s ratio gradually increased with the underground curing duration and eventually approached the stable value of 0.18. The failure type of compression samples was mainly single-sided shear failure. The development of tensile strength can be divided into two stages, and the stable value of the tensile strength was about 1.05 MPa. The development of cohesion can be divided into four stages, and the stable value was about 1.75 MPa. The stable value of the internal friction angle was about 25°. This study can provide significant references for not only the long-term stability evaluation of CGFACPB in the field but also the design of optimal recipe of the cemented paste backfill (CPB).

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“…At present, when designing underground operations, calculations for operational losses, and consequently, the deposit utilization factor [2], are separately performed. Also, calculations of rock bolt support loads [3][4][5][6] are separately carried out. In underground mining systems, the relationship between room and pillar geometry is known as a deposit utilization factor.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Room and Pillar Method Geometry on the Deposit Utilization Rate and Rock Bolt Load

Skrzypkowski

2019

Energies

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In this article, a model of ore deposit in form of a lense carried out in the MineScape program, is presented. The lense had a thickness of 30 m, length along the strike 200 m, and the depth buried was for 80 m to 110 m below the surface. In the first layer, counting from the lowest level, a room and pillar method with variable geometry was designed. The width and length dimensions for rooms and pillars were: 4 m, 5 m and 6 m, respectively. For the selected part of the deposit, three variants of the system with variable geometry of rooms and pillars were designed, for which the deposit utilization coefficient was determined. The next stage of the research was to determine the influence of the geometry of the pillars and rooms on the range of the rock destruction zone around room excavations. For this purpose, numerical calculations using the three-dimensional Examine 3D program, based on the boundary element method, were made. The results of numerical tests were used to calculate the load of the rock bolt support, which is currently used in the zinc and lead underground mine "Olkusz-Pomorzany" in Poland. Currently in the mine, the bolt spacing is 1 m × 1 m, and the technology for fixing the bolt rod is based on resin cartridges that completely fill the bolt hole. In order to spread the spacing of the rock bolt support and to apply segmental fixing of the bolt rod, in the laboratory tests, rock bolt supports with increased strength were tested. Based on the results obtained, it was found that the rock bolt can be installed segmentally, using a cement grout, and its spacing can be increased to 2 m.

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Long-term stability of a backfilled room-and-pillar test section at the Buick Mine, Missouri, USA

Cited by 73 publications

References 5 publications

Comparative stability analyses of traditional and selective room-and-pillar mining techniques for sub-horizontal tungsten veins

Comparative stability analyses of traditional and selective room-and-pillar mining techniques for sub-horizontal tungsten veins

Experimental Investigation on Mechanical Properties of In Situ Cemented Paste Backfill Containing Coal Gangue and Fly Ash

The Influence of Room and Pillar Method Geometry on the Deposit Utilization Rate and Rock Bolt Load

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