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By Jiang Su, Michal Uhrin

"The use of composite linings, consisting of permanent sprayed primary and secondary linings with a sandwiched spray applied waterproofing membrane is expected to improve efficiency and reduce lining thickness, but it also brings complex primary-secondary lining interaction. This issue is further complicated by the uncertainty regarding the long-term behavior and parameters of the sprayed concrete–sprayed membrane interface.This paper aims to address this issue by presentation of a series of numerical analyses of a typical shallow SCL tunnel in soft ground with a range of design assumptions on the interface behavior: (1) compression only; (2) compression and tension; and (3) compression, tension, and shear.The results demonstrate that the assumed interface behavior has a significant impact on the primary-secondary lining interactions. A design approach of ignoring the tension and shear bond at the interface may not be conservative particularly for serviceability. This paper explains the rationale behind these conclusions and discusses the implications for design.INTRODUCTIONSprayed Concrete Tunnel Lining SystemsSprayed concrete linings (SCL) have been used in conventional tunneling for decades. However, details of SCL systems may differ to a large extent depending on ground conditions and specific tunneling methodologies.In hard rock conditions, for example, drill and blast excavation is typically supported by rock bolts and sprayed concrete (NGI 2014). Such tunnels are usually designed fully drained and the above-mentioned support elements considered permanent without the need for a further inner liner. Therefore, there is no structural interaction between separate lining shells to consider.In conventional tunneling in the European Alps, a double shell lining is typically utilized, consisting of an outer (primary) sprayed concrete lining and an inner (secondary) cast-in-place concrete lining, separated by a waterproofing system. The primary lining normally includes rock bolts and may include other support elements. The waterproofing system is usually based on a plastic membrane and a geotextile fleece. The tunnel may be designed fully or partially drained or fully undrained. Although there are two structural lining shells interacting, investigation of such interaction is generally irrelevant to designers because the primary lining is considered only temporary (fully sacrificial in the long term). An overview of reasons for this assumption is given, for example, by Lemke (2014). The secondary lining is designed to resist all foreseeable loads on the tunnel. The primary lining may, in reality, interact structurally with the secondary lining during the life span of the tunnel. However, since the secondary lining design must cover all possible (extreme) scenarios, investigation of such interaction does not bring any value to the design."

Jan 1, 2016

By Ankit Jha, Javad Sattarvand, Aaron Young

Blockchain technology is one of the prominent disruptive technologies that are being implemented in several disciplines. The application of blockchains in the mining and mineral industry can provide utility to several processes especially when the industry is undertaking digital transformation. The governing principles of blockchain technology are applicable in undertaking transformation in several processes within the mining industry. This study investigates the applications of blockchain technology within the realms of the mining industry and identifies key areas of implementation. A systematic review of publications on academic platforms relating to blockchain technology in the mining industry did not retrieve a considerable number of articles. Consequently, a thorough review of white papers and articles authored by individuals on use cases within the mining industry is compiled and presented in this review article. This review article identifies all the potential areas within the mining industry where blockchains could provide value and improve processes through their implementation. The broad area of implementation of blockchains includes supply chain, traceability in spares parts, contract management, regulatory compliance and cybersecurity.

Mar 1, 2024

By T. P. Meloy

In the last decade increased and prolonged interest has been displayed in the use: of tunneling or rapid excavation to solve many of the urban and industrial problems confronting our society. There has been talk and action on the interurban rapid transit systems for major cities, and even preliminary designs for a Boston to Washington interurban transit system. Much of this interest stems from the search to the solution of our increasingly complex urban problems, where the surface area must be given over more and more to the inhabitants, and the subsurface for transit, utility and other services. While tunneling is not a panacea to urban ills it holds a real solution to many existing problems. There is also, among the tunneling experts, a growing confidence that technical problems of rapid tunneling can be solved. To solve these problems, R & D money must be invested. If it is to be money invested either by private industry or governments, there must be significant returns on the investment to justify the research and development need to bring about the breakthrough that will make tunneling a major contribution to the solution of urban problems. To make these economic studies more extensive and more accurate tunneling demand figures were needed. To this end, the Organization of Economic Cooperation & Development - OCED - included in its Conference on Tunneling a section on tunneling demand. As a result of the conference the organization for Economic Cooperation and Development issued a report entitled "The Advisory Conference on Tunneling - Report on Tunneling Demand 1960-1980. " This report was presented at the OCED Conference on Rapid Excavation, held at Washington, D.C. To obtain the data in the Report, questionnaires were sent to the OCED countries and 18 replies were received from Australia, Austria, Belgium, Canada, Denmark, France, Germany, Ireland, Italy, Japan, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, United Kingdom, and the United States. While it is true, that data were missing, that sometimes the definitions were confused, and that several countries provided no cost estimates at all, in general, this report contains the most comprehensive gathering of data that ever existed in the field. All data in the OECD report is expressed in terms of meters or cubic meters, and costs are in U.S. dollars.

Jan 1, 1970

By B. Slaker, M. M. Sears, G. Rashed

Ground falls represent a significant hazard at underground mines in the stone, sand and gravel (SSG) sector in the United States. Researchers from the U.S. National Institute for Occupational Safety and Health (NIOSH) are conducting detailed investigations into the complex loading conditions at underground stone mines operating in challenging conditions. This paper presents the application of numerical modeling to analyze pillar and roof stability at a dipping underground limestone mine.

By T. P. Meloy

The packed column flotation cell is an awesome separation device. Virtually unknown and untested, the packed column flotation cell is one of the ten most important developments in mineral processing of the 21st century. Though experimental and industrial data is limited, it is clear that the packed column flotation cell is two to three orders of magnitude better than the conventional flotation cell and one to one and a half orders of magnitude better than the open column flotation cell. With the modern packing taking up less than one percent of the packed column, column blocking does not occur. For a packed column operating 24 hours a day, 365 days a year, the estimated mean time between failures (MTBF) is one hundred thousand hours or roughly twelve years. With no moving parts, lower maintenance costs, lower power consumption and inherent operating stability, the packed column is a powerful separating machine. Because there is little meaningful data for comparing the packed column to the conventional flotation cell and the open column flotation cell, much of the material presented in this paper are guesstimates. They are disinterested guesstimate made by the authors after extensive theoretical work and reviewing the known facts. In the authors' opinion, no available data contradicts the guesstimate. The authors expect that there may be errors as large as three hundred percent. Even three hundred percent errors will not change the conclusions of this paper. The packed column flotation cell is a formidable separating device. To understand the problems of comparing the three types of flotation cells, consider the fact that the three cells may have different modes of separation. One of the authors, Meloy, believes that in the conventional cell, the primary particle separation takes place in the liquor with secondary separation taking place in the froth, while for open column flotation, all the separation takes place in the froth. However, he believes that in the packed column a large part of the separation may take place on the walls of the packing. If this is true, not only is the method of modeling each type of cell different, but the method of particle selection in the cell is different. This means that one type of cell may be better at differentiating between two different types of particles. There is a growing body of literature on open and packed column flotation. Suggested reading: (Clarke et al; Hucko et al; Li; Smith & Warren; and Yang).

Jan 1, 1994

By M. Fig, A. Juganda, M. Zurhorst, J. Brune, C. Strebinger, G. Bogin

"Understanding the airflow patterns in and around the longwall panel can help to identify poorly ventilated areas that may be prone to methane accumulation. Ventilation network modeling provides quick simulation time, and flexibility in adjusting airway parameters and ventilation controls. Such modeling is effective for analyzing linear ventilation networks in underground mines, but cannot compute flows in caved areas of hard rock mines or longwall gobs. The use of Computational Fluid Dynamics (CFD) enables a more detailed investigation of the interaction between the airflows in these caved areas but requires much longer computational times, designing complex meshes and determination of a variety of modeling parameters. Airway friction factors and ventilation controls are simple to implement in a network model but can be difficult to model and adjust in CFD. This paper will focus on using mine ventilation network simulation to identify and analyze key parameters that are affecting airflow distribution in and around the longwall panels, prior to more detailed analysis with CFD modeling, using the example of a longwall coal mine. INTRODUCTION In longwall coal mine ventilation systems common in the U.S., the main purpose of bleeder ventilation is to dilute methane gas and prevent the formation of explosive gas mixtures in the caved, poorly ventilated gob areas and adjacent mine workings. In longwall operation, these critical areas include the development headings inby the longwall face, and the gob. Methane-air explosions in these areas may be ignited by spontaneous combustion, rock-on-rock friction and other sources. Although rare, ignitions due to rock-on-rock friction caused by roof falls caving into the longwall gob are possible and were suspected in the Willow Creek mine explosions in 1998 and 2000 (Elkins et al., 2001; McKinney et al., 2001). Rock-on-rock frictional ignitions are difficult to prevent, as they occur in inaccessible areas. Therefore, rendering the gob area inert is essential to prevent the formation of explosive mixtures. Research by Gilmore et al. (2015) and Brune et al. (2015) has shown that gob inertization can be a difficult or impossible when using bleeder systems, since the flow of gases through the gob depends on the gob permeability and the amount of fresh air leaking from the face and the immediate roof caving conditions cannot be controlled by the mine operator. Having the ability to predict the location where explosive gas zones (EGZs) form inside the gob will be helpful for designing the best ventilation setup to minimize explosion and fire risks."

Jan 1, 2018

By Thomas R. Kuesel, Harvey W. Parker

INTRODUCTION This paper describes the use of a shield and compressed air for construction of a short section of a pair of twin single-track tunnels for the Metropolitan Atlanta Rapid Transit Authority (MARTA) transit system. Although only two blocks long, this section posed the greatest difficulties to both engineers and contractors, and is the most expensive section of line construction on the MARTA system. All this derives directly from its setting--these tunnels had to be constructed through mixed-face conditions. SETTING The Broad Street tunnels form a link between the Peachtree Center and Five Points Stations, in the heart of Atlanta's central business district (Figure 1). Peachtree Center sits atop a solid rock ridge, which inspired the design of a deep rock-mined station, as described in the 1979 RETC. Five Points Station is MARTA's hub--the intersection of the system's two main branches. It is located in the old railroad gulch, a filled-in erosional valley at the base of Peachtree Ridge, and was constructed by open-cut methods. The alignment and profile of the Broad Street tunnels were closely constrained by these two adjacent anchors, and in the six-block stretch between them there was very little room for maneuvering. Since the rock ridge petered out about in the middle of the section, it was evident at the outset that there would be about two blocks of rock tunneling at the north end, two blocks of soft ground construction at the south, and two blocks of mixed-face in between. It is this central two-block section that is the focus of this paper.

Jan 1, 1981

The following errors were inadvertently included in "How millisecond delay periods may enhance or reduce blast vibration effects" by R.M. Wheeler in the September issue of Mining Engineering.

Jan 1, 1987

By Jozef Stachulak

Prof. H. Bystron: "An Application of the First Law of Thermodynamics to Winter Dry Air Flow in Mr. Stachulak's Mine Model". [ ]

Jan 1, 1980

By Emanuele Catelli, Paolo Vicentini, Manuel Petitat, Paolo Lanfranchi

"More than 800 million tons of material will be excavated during large underground projects such as tunnels, undergrounds and power plants by 2030 in Europe only. The raw material excavated is often classified as waste, which involves environmental impact and transport issues: landfill areas, CO2 emissions and noise. But how can such massive amounts of material be transported, processed and deposited? Using the example of the AlpTransit Ceneri Base Tunnel (15.4 km), we show that suitable excavated materials can be used sustainably as a primary resource for tunnel concrete. This requires careful planning of the installations and storage areas by the client, timely building of the processing plants and other handling facilities outside the tunnel and a continuous evaluation of the raw material quality. 1. INTRODUCTION Spoil management is a central element of large construction projects. The systematic reuse of suitable excavated material not only saves natural resources, reduces transport distances and landfill volume, but can also decrease overall construction costs. Ideally, all of the concrete needed for tunnel lining can be produced with this on-site material. Such a natural resource management concept was applied for the construction of the new Gotthard Base Tunnel (L = 57 km). Spoil management concepts are, how-ever, difficult to implement and call for innovative techniques, sophisticated logistics and organization. In the context of large projects, environmentally friendly transport, processing and storage of millions of tons of excavated loose material represent another logistics challenge (Simmen & Lieb, 2010). This paper shows key factors that led to the successful completion of spoil management at the Ceneri Base Tunnel, which constitutes a part of the AlpTransit Gotthard Project (Figure 1)."

Jan 1, 2016

By Robert T. Beckman

Education of inspection and operating personnel is essential to protection from radiation hazards in the mining industry. For over 10 years, MSHA has presented the only formal course on radiation measurements and control available to the mining community. Course objectives and content are described in this paper.

Jan 1, 1981

By C. M. McCulloch

More and more mining underground is being conducted using the longwall method. Likewise, many new surface mines use area or mountaintop removal methods. These methods can have a significant impact on surface and groundwater resources. The overall study of the effects on surface and groundwater from mining is referred to as the probable hydrologic consequences (PHC) determination of mining and reclamation. Collection and interpretation of information concerning groundwater and surface water quality and quantity, as well as detailed geologic analysis, is required to adequately define the impacts of mining. This paper discusses the present day requirements and methodology of preparing a PHC for a large mining operation in the eastern coalfields.

Jan 1, 1995

By C. R. Tinsley

Valuations can be molded, twisted and misinterpreted. Cases of spurious scope setting; limits to the information or access by the valuer; difficulties with the lack of comparative valuations; inappropriate valuation methods and outright speculations are described. None should be accepted by an experienced, independent minerals valuer. The Australasian Institute of Mining and Metallurgy (TheAusIMM) is working on a Valmin Code for which a Manual of Best Practice and Valuation Guidelines may be developed.

Jan 1, 1995

By Sotiris N. Kamenopoulos, Zach Agioutantis

Rare earth elements (REEs) are considered critical minerals for the industrial and defense sectors. In 2018, the U.S. Department of the Interior presented the final list of critical minerals that are vital to the U.S. economy and defense [1], which included REEs among other mineral commodities. REEs are not rare, despite their name, but economically viable deposits of REEs can be found only in certain geographical areas, and the political and social conditions characterizing these areas may not always be in favor of mining operations. Mining operations may be placed in great operational and financial risk if operations are planned in such areas. Erroneous decisions by decision makers may lead to a chain of events that can completely shut down a mining project. 

By M. B. Mooiman

Cyanidation of gold and silver ores by conventional mining and milling techniques has been practiced for over a century. During the past decade, heap leaching has emerged as a viable process for treating certain gold and silver ores. (1) The rapid development of heap leaching for gold and silver ores is largely a result of lower capital and operating costs and faster start-up time than that offered by conventional mining and milling. In general, these features make heap leaching an ideal approach for exploiting either small or large low-grade disseminated deposits of gold and silver considered to be uneconomic by conventional methods. The development of heap leaching technology has evolved from the operations initiated in the western United States. The basic components of a typical heap leaching operation are depicted in Figure 1. Run-of-mine or crushed ore (usually 1 to 5 ppm gold) is delivered to specifically prepared impervious pads. Alkaline cyanide solution is applied to the surface of the heap and allowed to percolate through the heap (typically 10-30 ft high). Pregnant leach solution which drains from the heap is collected and stored in tanks of sufficient size or in collection reservoirs. Gold and silver are recovered from the pregnant solution and the barren solution is recirculated back to the heaps after reagent make-up.

Jan 1, 1983

By Jon A. Hummer, MICHAEL R. SHAHAN, Aleksandar D. Bugarski, Shawn Vanderslice

Occupational exposures to respirable dust and submicrometer aerosols emitted by diesel-powered equipment are a health concern for underground mining operators and regulators. A study was conducted in an underground mine with the objective to identify, characterize and source apportion airborne aerosols at the setup face and recovery room during longwall move operations. 

High pressure grinding rolls have found widespread acceptance for cement processing, and are now making their debut in the metalliferous minerals industry. Significant energy and wear material savings appear achievable in many applications. This paper re- views the technical literature on this important, emerging technology.

Jan 1, 1997

By R. Schlüter

"The global mining industry is facing increasing challenges in terms of geological, technological and social aspects. Potential exploi-tation of deposits shows a tendency to increasing depth with complex ores and decreasing grades. A promising approach to deal with these constrains is by applying alternative extraction methods like (bio-)hydrometallurgy as in-situ leaching (ISL) technology. The Bergakademie Freiberg University of Mining and Technology established the “Biohydrometallurgical Center for strategic Elements” (BHMZ) to foster the interdisciplinary research along the entire biohy-drometallurgical process chain to extract indium from sulfide ores. The involved Department of Underground Mining Methods deals with the design and implementation of a pilot-scale underground testing facility for microbial in-situ stope leaching in its “Research and Educational Mine”. This paper discusses the potential of in-situ bioleaching under technological aspects. In addition, different conditioning approaches based on hydraulic and explosive methods for enhanced permeability in the formation are introduced and the gathered data will be presened. INTRODUCTION A reliable, substantial and sustainable supply of raw materials is of crucial importance for any industrialized country. This dependency applies to “strategic elements” including rare earth elements (REEs), platinum group metals (PGMs) as well as a variety of other metals like indium and germanium which are needed for high-tech industry and products such as electric and electronic devices, fibre optics and laser technology (Barakos et al., 2016; European Commission, 2010). Due to the economic growth of the BRIC-countries (Brazil, Russia, India, China), the resource policy of China as well as the volatile world mar-ket prices of different metals the availability of these critical raw materi-als and therefore the dependency of the high-tech producing countries has become increasingly important (Barakos et al, 2016). Adequate supply is often affected by the increasing depth of de-posits, lower metal concentrations and more complex ore mineralogy. In addition, mining activities are increasingly restricted by their envi-ronmental and social impact and footprints. As a consequence, con-ventional mining and processing methods are limited by high energy consumption and technical constraints."

Jan 1, 2018

By E. W. Hawk

The power generation industry may be required to reduce CO, emissions if regulations related to global climate change are enacted. Coal-fired generation, which emits 82% of the power sector CO2, would be a likely target for CO2 reduction. Compliance with the Kyoto protocol will require a 30% reduction from the projected year 2012 emission level even with moderate load growth. This paper describes an analysis of power industry CO2 reduction options and their costs to assess how a generator would make compliance decisions under a mandatory CO2 emissions reduction program. Carbon sequestration, fuel switching and new plant construction are considered.

Jan 1, 1999

By R. J. McGregor, Deepak Malhotra

Engineers frequently encounter situations where decisions that are counterintuitive to the logically trained engineering mind are made because of other influences, whether they be financial, social, cultural, or environmental. Such influences can overrule the "logical" decision-making process. The aim of this book is to explore some of the nontechnical issues, which most engineers don't learn about in school, that can have a major impact in the mining industry. This chapter gives a brief overview of this volume and introduces the topics that will be addressed.

Jan 1, 2001