Research on Roof Fracture Characteristics of Gob-Side Entry Retaining with Roof Cutting and Non-pillar Mining in Thick Coal Seam, China

Based on the S1201-2 large height mining in the 2–2 coal seam of Ningtiaota colliery with on-site microseismic measurement, physical simulation and theoretical analysis methods, this paper explores the rule of roof movement in thick coal seams with roof cutting and non-pillar (hereinafter referred to as RCN-P) mining, so as to obtain scientific and effective theoretical basis for entry support and to summarize the regional structural characteristics and dynamic periodic fracture characteristics. As can be seen from microseismic events, the entry roof is featured by "two zones and one line" along the horizontal direction, namely, the crack generation area, the roof movement area. Additionally, and the obvious lateral breaking of the entry roof on the coal wall is a typical feature of the thick coal seam with RCN-P mining. The roof is vertically divided into "three zones", the crack generation area, the roof movement area and the crack development area. The roof cutting activity mainly affects the overburden activity within the basic roof height range, which is also the roof movement area. In addition, the distribution frequency and the intensity of microseismic events indicate the roof periodic breaking characteristics. The "breaking pressure relief,” “advanced crack development,” and “the limit breaking state” of roof breaking corresponds to the initial, middle, and final stage of breaking in the periodic weighting process, respectively. Compared with the normal mining, the RCN-P mining reduces the periodic weighting length and increases the pressure strength. As is shown in the physical simulation experiment, the basic roof and the cutting control layer in the "regional structural characteristics" constitute the “large” and “small” structures with RCN-P mining. The basic roof key layer is the core to control the stability of the strata, and the breaking process from the cantilever beam to the short masonry beam of the roof-cutting control layer is the main cause of the entry stress. Correspondingly, the basic structure model of “short masonry-hinged” roof was proposed and the calculation method of support was established for the entry with RCN-P mining in thick coal seam, providing a research foundation for scientific and effective rock formation control.

Research on Roof Fracture Characteristics of Gob-Side Entry Retaining with Roof Cutting and Non-Pillar Mining in Thick Coal Seam, China

Based on the S1201-2 large height mining in the 2-2 coal seam of Ningtiaota colliery with on-site microseismic measurement, physical simulation and theoretical analysis methods, this paper explores the rule of roof movement in thick coal seams with roof cutting and non-pillar (hereinafter referred to as RCN-P) mining, so as to obtain scientific and effective theoretical basis for entry support and to summarize the regional structural characteristics and dynamic periodic fracture characteristics. As can be seen from microseismic events, the entry roof is featured by "two zones and one line" along the horizontal direction, namely, the crack generation area, the roof movement area. Additionally, and the obvious lateral breaking of the entry roof on the coal wall is a typical feature of the thick coal seam with RCN-P mining. The roof is vertically divided into "three zones", the crack generation area, the roof movement area and the crack development area. The roof cutting activity mainly affects the overburden activity within the basic roof height range, which is also the roof movement area. In addition, the distribution frequency and the intensity of microseismic events indicate the roof periodic breaking characteristics. The "breaking pressure relief,” “advanced crack development,” and “the limit breaking state” of roof breaking corresponds to the initial, middle, and final stage of breaking in the periodic weighting process, respectively. Compared with the normal mining, the RCN-P mining reduces the periodic weighting length and increases the pressure strength. As is shown in the physical simulation experiment, the basic roof and the cutting control layer in the "regional structural characteristics" constitute the “large” and “small” structures with RCN-P mining. The basic roof key layer is the core to control the stability of the strata, and the breaking process from the cantilever beam to the short masonry beam of the roof-cutting control layer is the main cause of the entry stress. Correspondingly, the basic structure model of “short masonry-hinged” roof was proposed and the calculation method of support was established for the entry with RCN-P mining in thick coal seam, providing a research foundation for scientific and effective rock formation control.

Bioaccessibility Of Potentially Toxic Elements In Mine Residue Particles

Mining companies use to abandon tailing heaps in countryside regions of Mexico and other countries. Mine residues (MR) contain a high concentration of potentially toxic elements (PTE). The wind can...

Deep-sea mining

Mining the extensive accumulations of minerals on the seafloor of the deep ocean might provide important resources, but it also has the potential to lead to widespread environmental impacts. Some of these impacts are unknown, and some may differ for the three main resource types: polymetallic nodules, seafloor massive sulphides, and polymetallic (cobalt-rich) crusts. Here, we detail the mining processes and describe the ecosystems associated with the minerals of interest. We then explain the expected impacts of mining, and discuss their potential effects on deep-ocean ecosystems. We also highlight the missing evidence needed to underpin effective environmental management and regulation of the nascent deep-sea mining industry.

Introduction

Mining in colonial Latin America and the early modern Iberian empire has been studied from a variety of disciplinary perspectives, including archaeology and archaeometallurgy; philosophy; art history, visual studies, and material cultural analysis; literary studies; social, labor, legal, and economic histories; and the history of science. This book adopts a language-centered approach that incorporates methods of all of these fields, especially discursive, visual, and historical analysis. The introduction reviews current scholarship in the study of mining and argues for the importance of a new approach to the history of metals – one that centers the knowledges of Indigenous, African, and South Asian miners, refiners, and mineralogists.

Discovery of new levansucrase enzymes with interesting properties and improved catalytic activity to produce levan and fructooligosaccharides

Mining for new levansucrase enzymes with high levan production, transfructosylating activity, and thermal stability and studying their kinetics and acceptor specificity.

Approaches to Supporting Local and Community Development

Mining is the largest sector of the Zambian economy but the relationship between mining companies and their host communities has been fractious, without a clear path towards sustainability. The severe social, economic, and environmental impacts of mining have been compounded by perceived shortcomings in corporate social and environmental responsibility programming by the industry, and by fragile regulatory capacity on the government’s part. This chapter examines the modalities and results of mining community development programmes in Zambia as part of the broader discussion on how large international mining companies can, and do, contribute to local and community development. It narrates the approaches adopted by five multinational mining corporates, two of which are Chinese-owned, and discusses their advantages and disadvantages.

ANALISA PENENTUAN LAYAK TAMBANG BENTONIT PROVINSI JAWA TIMUR DENGAN ANP

Mining activity can cause environmental damage if the environmental balance, the environmental carrying capacity and good management of the mining resource are not considered. Therefore they should be analyzed to determine the feasibility of mining. The objective in this study is to select the distribution of Bentonite that meet criteria based on the environmental potential in the region of Malang and Blitar in East Java Province. The method used to determine the feasibility of mining is the Analytical Network Process (ANP). ANP is one method that is able to represent the interests of various parties to consider the interplay between the criteria and sub criteria. The study found that village of Birowo, Binangun sub district, Blitar district is the most viable potential bentonite of mines.

Self-resistance guided genome mining uncovers new topoisomerase inhibitors from myxobacteria

Mining the genome to harvest from the metabolome: a well-directed search for bioactive natural products unearths the pyxidicyclines fromPyxidicoccus.