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2 Archives of Mining Sciences

2 2020

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Revalorization of mineral coal, to obtain carbonaceous materials with high added value

Vidal-Lombas Juan-José, Álvarez-Fernández Martina-Inmaculada, Casado-Sulé María-Concepción, Prendes-Gero Maria-Belen, Suárez-Domínguez Francisco-José

Archives of Mining Sciences

2020

Vol. 65, no. 2

225--239

This paper shows the possibility that the mineral coal existing in the mining basins of northern Spain have a high added value. This would facilitate its future use in different fields such as new materials, nanotechnology, energy use in situ, coal bed methane, enhanced coal bed methane and coalmine methane.An analytical study of mineral coal samples is carried out. The samples come from two deposits loca-ted in coal basins of the Cantabrian Mountains. The duly prepared samples are subjected to an activation process. Within this transformation, different treatments are applied to different sub-samples. Some of the sub-samples suffer a previous demineralization by successive attacks with acids, followed by oxidation and pyrolysis. Finally, all of them are activated with CO2 and H2O(steam).The carbonaceous products resulting from each treatment are characterised. The results show that all the pre-treatments used were positive for the textural development of the materials. Likewise, proper management of the processes and of the different operating variables allows the procurement of carbo-naceous materials with a “tailor-made” structural development of the coal type. This material receives the name “activated” and can be employed in specific processes.

Optimal support design for galleries located in poor quality rock mass and under the influence of mining works

Vazquez-Silva Daniel, Prendes-Gero Maria-Belen, Álvarez-Fernández Martina-Inmaculada, González-Nicieza Celestino, Laín-Huerta Carlos, López-Gayarre Fernando

Archives of Mining Sciences

2020

Vol. 65, no. 4

851--867

In this work, the sup port of two general galleries located in poor quality rock mass and subjected to the influence of high thickness coal layer exploitations is designed and optimized. The process is carried out in four phases:A first preliminary support is defined employing different geomechanical classifications and applying the New Austrian Tunnelling Method (NATM) using bolts and shotcrete.An instrumentation campaign is carried out with the goal of analysing the behaviour of the support. The study noticed the failure of the support due to the time of placement of the different elements.A back-analysis using the Flac and Phases software has allowed the evaluation of the properties of the rock mass and the support, the study of the influence of the time of placement on the component elements (bolts and shotcrete), and the redefinition of that support.Subsequently, a new support is designed and optimized through numerical modeling after the start of mining without experience in these sizes of sublevel caving that caused the failure of the previously designed support. The new support is formed by yieldable steel arches that are more suitable to withstand the stresses generated by nearby mining work.