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By Graham A. Davis

?The ideas of economists and political philosophers, both when they are right and when they are wrong, are more powerful than is commonly understood. Indeed, the world is ruled by little else. Practical men, who believe themselves to be quite exempt from any intellectual influences, are usually the slaves of some defunct economist. Madmen in authority, who hear voices in the air, are distilling their frenzy from some academic scribbler of a few years back. I am sure that the power of vested interests is vastly exaggerated compared with the gradual encroachment of ideas. . . . But, soon or late, it is ideas, not vested interests, which are dangerous for good or evil.? John Maynard Keynes The General Theory (1936) Policy analysts, economists and others have tradition-ally considered mining and mineral wealth a boon, providing rich countries with the resources needed to sustain their modern industrial economies while helping poorer countries generate the foreign exchange, tax revenues and other assets necessary for economic growth and development. Nevertheless, this conventional view has always had its critics.

Jan 1, 2008

By Dean Brox

The Galore Creek Mine project is one of the newest major mining projects under development in Canada. The project is located in a very remote area of northwestern British Columbia and is being developed by NovaGold Resources and Teck-Cominco of Vancouver. The mine project comprises one of the largest and highest grade undeveloped porphyry-related gold-silver-copper deposits in North America. In order to access the mine site a new 120 km road is required including a 4.4 km mine access road tunnel. Glaciers with heavy snow pack cover approximately two-thirds of the tunnel alignment with a maximum cover of 1200 m. The size of the access road tunnel is about 50 m2 and has been designed as a large single lane road tunnel to accommodate the transport of large size mining equipment for mine start up and ongoing operations. The rock conditions along the tunnel alignment comprise very strong volcanic rocks. Key services for mining operations will be incorporated into the tunnel comprising diesel and power as well as the concentrate pipe-line. Structural portal canopies and portal houses have been incorporated into the tunnel design due to the risk of rockfalls and avalanches in the portal areas. The mine access road tunnel is a significant and critical-path component to the overall project to provide vehicular access to allow construction of the mine site. In order to meet the expected mine start up date the construction of the tunnel works have commenced prior to any other works at the mine site and will be constructed entirely by helicopter support. The tunnel works commenced in the summer of 2006 with the advanced excavation of the overburden materials at the portals. Tunnel construction from the North portal commenced in the spring of 2007. When completed, the mine access tunnel will be the longest private road tunnel in North America. The key design and constructability issues for the mine access road tunnel project are presented and discussed along with a construction status update as of late 2007.

Jan 1, 2008

By R. A. Franks

An evaluation of a nuisance-emissions-discriminating smart mine fire sensor system was made in an operating coal mine. These field evaluations were conducted to determine the sensor system?s ability to discern nuisance emissions, such as diesel exhaust, emissions from flame cutting and welding operations or hydrogen gas from a charging station, from real fires and to compare the number of falsely reported fire alarms generated between the sensor system and a standard carbon monoxide (CO) monitor. The sensor system?s ability to operate successfully in the working environment of an operating coal mine was also evaluated. The smart mine fire sensor system consisted of four sensors whose data outputs were fused with the use of a neural-network-type computer program. Long-term trials were conducted in a haulage way, a belt entry, and a track entry. The system functioned successfully in the belt entry, in accordance with its developmental goals, where the sensor system even discriminated events not anticipated during development. It was not totally effective in the haulage way and track entry, though, due to a combination of significant diurnal air temperature variations, dust, and mechanically induced vibrations. Also, deteriorating rib conditions contributed to operational problems in the haulage way evaluation. In general, the smart mine fire sensor provided nuisance emissions discrimination and was shown to be a viable new approach for mine atmospheric monitoring, enhancing miner safety. This paper describes the in-mine evaluation of the smart mine fire sensor system and discusses recommendations for improving the system. Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

Jan 1, 2008

By W. J. Schlitt

The development of forced aeration as an approach to enhancing copper sulfide leaching is traced from its earliest development up to present day operations using this technology. Both large-scale field tests and commercial operations are covered. The historical portion is preceded by an introductory discussion of the role of air (oxygen) in sulfide leaching. Sufficient aeration may be achieved via naturally induced convective airflow. However, cases are identified where this is insufficient, leading to retardation of the sulfide leach rate. For these situations, forced aeration may be beneficial. The historical portion of the paper focuses on the major field tests that have been conducted in Montana, Nevada and Utah, along with commercial operations in the United States, Australia, Chile and Peru. The paper concludes with some general comments about the applicability of forced aeration, which are based on the information developed to-date.

Jan 1, 2006

By Lawrence Pelham

Introduction Fluorspar demand or consumption has been taken for granted in recent years, except for those that produce, market, or consume the commodity. Thinking used to be that as the steel and aluminum industry goes, so goes fluorspar. This is much less true today. The industry is becoming more dependent on chemical industries that feed primarily off hydrofluoric acid (HF) production. The US Bureau of Mines (USBM) published an assessment of world fluorspar reserves and resources. It created a foundation of valuable data that can be used to monitor fluorspar availability. Celebrations were held this year commemorating the 100th anniversary of the isolation of fluorine. The US and other countries continue to struggle with the controversy of ozone depletion and the effect of fluorocarbons on the atmosphere. Goals for the government's strategic stockpile are being reevaluated. The market for fluorine chemicals is changing and diversifying, making it a challenge to assess and forecast fluorspar/fluorine demand. US production and distribution Fluorspar Fluorspar shipments from US mines reached an all-time high near the end of World War II in 1944 at 375 kt (413,800 st). Eighty-two mines produced more than 453 t (500 st) each, and 10 mines produced more than 9 kt (10,000 st.) each. Illinois supplied 43% of total shipments. Consumption in 1944 was 372 kt (410,200 st), of which 56% was used by steel producers and 32% by HF producers. This was the last year that US production exceeded US consumption. The post-World War II record for fluorspar shipments occurred in 1951 at 315 kt (347,000 st) 58 mines produced more than 453 t (500 st) and eight mines produced more than 9 kt (10,000 st).

Jan 11, 1986

By Peter White

The Hemlo Gold District, located on the north shore of Lake Superior, was discovered in 1981 and will become one of the largest gold mining camps in Canada. Three major Canadian mining companies are presently developing large orebodies and are scheduled to commence production at various times through 1985 and 1986. This paper describes the types of shaft sinking equipment and technology being used by contractors in constructing the required shafts to depths below 1000 metres. The principal shaft design criteria, types of shaft sinking machinery and relevant manpower allocations are discussed.

Jan 1, 1985

By Aram Grigoryan

This paper addresses the challenges of designing the underpinning of major sub-way station with 4 operating tracks. No. 7 subway extension crosses under the existing 42nd street subway station on the 8th Avenue line. Understanding the history of the original construction, of the current structures and their condition were instrumental in developing a feasible underpinning design that is integrated with the design of the new tunnels. The existing 8th Avenue subway station has a lower abandoned level. Several alignments and corresponding underpinning schemes were studied. The design allows new tunnel construction under the station without interruption of station operations.

By M. Rufli

Until not so long ago most ring geared mills were operated with fix speed motors only. By using the latest generation of medium voltage frequency converters, new possibilities have arisen to improve the grinding process. Beside all the direct and indirect advantages, several dedicated functions have now been implemented for ring geared grinding mills in the minerals industry. The sophisticated operational functions ensure a smooth, safe and reliable operation with minimum stress for the mechanical equipment and therefore utmost availability of the mill. Several papers have already been presented concerning the benefits of using this state of the art technology for mill drives. Now this paper is focusing on the experiences gained with this kind of sophisticated ring geared mill drive system rather than only show and explains the operational benefit of the different functions. Several measurements of different operating conditions, starting, frozen charge remover, controlled roll back, backlash, etc., made on an installed and commissioned 2 x 5 MW dual pinion ring geared mill drive system will be shown and discussed. The accuracy of the load sharing between the two 5 MW motors during starting, normal operation and stopping will be demonstrated using real measurements from an operating system. Finally the inherent features of these drive systems are briefly discussed.

Jan 1, 2011

By Michael Stanwood

Project feasibility no longer involves just technical and economic viability-today's feasibility study must include environmental, regulatory, and political considerations as well. While the US now appears at least somewhat committed to developing synthetic fuels, including oil shale, it is the environmental issues, rules, regulations, and guidelines that will play the major role in determining the timing, magnitude, and overall scope of synfuel development in the coming years. The key environmental obstacle affecting oil shale development is uncertainty. Although oil shale may be the most environmentally studied "new" technology in the world, little is known with much degree of certainty about potential environmental consequences of one full-scale commercial facility, or the effects of a massive development effort in a relatively pristine and sparsely populated area. Other primary environmental uncertainties include: • Environmental compliance costs and their effects on investment decisions; • The reliability and acceptability of anticipated pollution control technologies; and • The confusing, time-consuming environmental regulatory framework, which requires more than 100 permits, clearances, and reviews before development occurs. This discussion will focus on the latter uncertainty, and will describe he current status of potential constraints to oil shale industry development in five areas: water availability; water quality degradation; air quality degradation; reclamation and spent shale disposal; and community impacts.

Jan 1, 1981

By J. B. Gwiazda

Introduction Thick seams constitute a considerable portion of Polish coal reserves. In producing mines and those under construction, the reserves where the height is more than 4.5 m (15 ft) total about 24% of all the hard coal reserves. The reserves that are under urban and industrial areas can be extracted using stowing methods for surface protection. About 50% of thick seam reserves can be extracted by caving methods. Thick seam mining methods Thick seams are usually extracted by multilift methods. There are some methods of thick seam mining that generally can be divided into caving and stowing methods. The stowing method is more expensive, but must be used when mining to protect surface features. The more known methods of thick seam mining include • extraction of thick seam in ascending order with stowing ; • thick seam mining in descending order with consolidated stowing; • thick seam mining with gob consolidation; • thick seam mining in descending order with roof caving ; • sublevel caving thick seam mining system; and • thick seam mining system using an artificial roof. Thick seam mining with introduction of an artificial roof The most advantageous method of thick seam mining is the method using an artificial roof. The artificial roof usually consists of wire mesh. Such wire mesh must be durable and must prevent small rock fragments from passing through. The mesh is usually made of steel properly protected against corrosion. The artificial roof is placed on the coal floor of the top slice (Fig. 1). Caving rock falls on the artificial roof and is thus separated from the coal. The next slice is extracted under the artificial roof. The producing face of the next slice must progress within 10 m (33 ft) behind the front of the first slice. As the second producing face progresses, the wire mesh moves down on the coal floor and may be used as an artificial roof for the next slice. Thus, one artificial roof allows the extraction of several consecutive slices. Application of the artificial roof allows for clean extraction and reduces coal losses. It also eliminates the hazard of spontaneous combustion. Introduction of the artificial roof has been limited due to a lack of artificial roof laying equipment. Manual laying of wire mesh is a labor-intensive operation, and it delays face progress, resulting in poor productivity. To eliminate these problems, artificial roof laying equipment was designed at the Polish Central Mining Institute. The support and the method of laying operation is covered by a patent. Artificial roof laying powered support To extract thick seams using an artificial roof, four-leg shield supports with lemniscate linkage were developed (Fig. 2). This shield is used in the first top

Jan 3, 1987

By J. C. Schneider, G. Van Weert

Hydrochem Developments Ltd. has developed and put into full scale operation a novel type of vertical flotation column incorporating a multiplicity of mechanically agitated stages. Characteristics of this flotation column include a low height to diameter ratio, high upgrading factors and the possibility of modifying geometry and operation to specific flotation requirements. A commercial unit is currently handling up to 100 tpd rougher concentrate at Dickenson Mines Limited, Balmertown, Ontario. Design parameters and plant performance will be discussed.

Jan 1, 1988

Face and pillar bursts, bumps and bounces are violent failures that occur in underground coal mines in response to a complicated interplay of face and pillar geometry, seam depth, coal properties and interactions between roof, seam and floor strata. Additional complications arise from the presence of gas, mainly methane, and associated pressure and flow that vary with time and are further influenced by the rate of face advance. Where gas plays a dominant role, the term outburst is often used; where stress concentration is primary, terms such as burst, bump or bounce may be used. Hargraves [1983] presents an often cited review of outburst phenomena with emphasis on Australian conditions. Beamish and Crosdale [1998] indicate outbursts have occurred for over a hundred years and present tabulations of outburst numbers in major coal basins throughout the world. A central consideration is the rate of depressurization that occurs in the course of mining. Outbursts are not limited to coal seams and adjacent strata; they also occur in salt and potash mines [Molinda et al 1988]. Stress concentration and gas pressure act in consort, so the combined action is important to understanding the mechanics of bursts or outbursts and to the development of measures to reduce the associated hazard. Gas flow is a complicated phenomenon associated with diffusion of gas from micro-pores and the flow of gas along cleats. Laboratory measurements indicate both are dependent on stress and pressure [Harpalani and Ouyang 1998]. Moreover, gas permeability in porous media is often many times water permeability [Klinkenberg 1941]. However, there is also evidence that gas and water permeability are similar at elevated stress and follow Darcy?s law [Dabous et al]. Gas flow is also of importance to mine ventilation. Price et al [1973] in cooperation with personnel of the former U.S. Bureau of Mines developed finite difference models to estimate methane emission in mines in the Pocahontas No. 3 and Pittsburg seams using a premining pressure of 4.69 MPa (680 psi) and Darcy's law implying laminar flow. However, the effects of stress were not taken into account. In this regard, mine measurements of permeability are usually based on Darcy?s law [Peide 1990]. Early models of gas flow with stress effects were one-dimensional in space and time (x,t) and were developed with the goal of estimating the gas pressure profile from the face into the seam as time passed [Schlanger and Paterson 1987, Zou and Yu, 1999]. A zone of high permeability adjacent to the mining face was recognized in these early models. Later models based on the popular finite element method allowed two spatial dimensions (x,y) and variation in time (t) and for coal seam heterogeneity [Tang et al, 2002]. Zhu et al [2007] formulated a set of nonlinear equations involving a complicated stress-pressure-permeability relationship for application to coal seam gas flow and concluded the coupling was important but failure of coal should also be considered. Wold et al [2008] used a hybrid finite difference - finite element model interleaved with a reservoir simulation model to study outbursts based on extensive mine and laboratory measurements. An important feature of the modeling was the use of spatially variable material properties and Monte Carlo simulation to obtain quantitative estimates of outburst conditions and probabilities. Connell [2009] used the same reservoir simulation model as Wold but used the popular finite difference code FLAC3D for hydro-mechanical responses to evaluate two permeability relationships, one depending on porosity and the other on stress, and concluded that permeability changes with gas production were more complex than computed by either permeability model. Gadde [2010] in an integrated laboratory and field study of coal pillar strength explored the effect of spatial variability and concluded that design based on average strength was acceptable in some circumstances, although gas pressure was not an issue. Liu et al [2011] also applied a FLAC code to analyze two-dimensional gas flow and deformation of layered but homogeneous strata in a Chinese coal mine using a strain-softening model and concluded that damage and gas pressure were important to strata safety relative to the case without gas.

Feb 27, 2013

By G. L. Dollinger, J. P. Kindsvater, J. A. Gibson

DESIGN AND DEVELOPMENT OF A MOBILE MINING MACHINE INTRODUCTION Until recently, developing tunnels in hard rock has been accomplished either by the drill and blast method or by using large tunnel boring machines. Combining the flexibility of drill and blast with the safety, efficiency and productivity of a TBM has been the objective of mining machinery producers for many years. In 1979 The Robbins Company began developing a new type of tunnel boring machine called the Mobile Miner to meet these objectives. The development and testing of the Mobile Miner is the subject of this paper. CURRENT MINE DEVELOPMENT METHODS Both the drill and blast method and the use of a TBM have notable advantages and disadvantages. The drill and blast method, for example, allows much more flexibility, requires less setup time and has a lower initial cost than a TBM; however it requires the use of high explosives and blasting has a disrupting effect on the rock surrounding the development. A TBM, on the other hand, is safer to operate, more efficient, more productive and produces smooth tunnel walls without disturbing the surrounding rock. In longer straight drifts it will easily out distance the drill and blast method. The TBM, however, is limited to boring a circular cross section tunnel which must then be modified if a flat floor is required. It also has a higher initial cost and an extended setup period.

Jan 1, 1985

By M. Galetakis, C. Roumpos

A sustainable coal industry needs to achieve a number objectives concerning mainly with superior utilisation of deposits and improved environmental performance. Modern quality control systems, which are greatly based on the on-line analysers, play an important role in achieving sustainability targets. This paper discusses the testing and application of on-line ash analysers installed in the Ptolemais and Megalopolis lignite mines in Greece and examines the possibility of using this type of analyser to control blending and homogenisation operations. The effect of the accuracy of on-line analyser to control process, when used for the characterization of low rank coals with complex and variable composition, such as greek lignites, is examined.

Jan 1, 2005

By Michael Feroz, Marcus Jensen, James E. Lindell

The Southern Nevada Water Authority (SNWA) operates two water-intakes in Lake Mead, located 20 miles east of Las Vegas, Nevada. Severe drought has caused decline in lake level by 85 feet since 2000 and future declines are expected. SNWA will construct a third deep-water intake to ensure existing water system capacity. This paper describes expected construction challenges for the new project that consists of: an intake structure and tunnel beneath the lake, pumping station, pipeline to connect existing treatment facility, and interconnecting underground adits. The project will be completed in the year 2012 for total estimated cost of approximately $600 million.

Jan 1, 2007

By John Reilly

Traditional methods of project procurement of have remained virtually unchanged in the U.S. infrastructure construction industry for more than 50 years. The traditional method, Design-Bid-Build (DBB), uses a two-step process that separates planning and design from construction. Design is generally done by the public agency and their consultants and the subsequent construction contract is procured from the private sector, almost always by a “low-bid” approach. This method has worked well for many projects, delivering quality work for the lowest bid price. This is particularly true for those projects where the work, and the public agency’s management procedures, are well understood by the contracting community and there is relatively low uncertainty in the work or conditions, particularly geotechnical conditions for underground construction. However, concerns exist with the DBB process. It is time consuming because all planning and design work must be completed prior to beginning any construction work and it is of concern for complex or large projects, plus those with significant risk, where the separation of design and construction, in conjunction with pressures resulting from the low-bid environment, often result in substantial cost and schedule increases. Frequently, these increases occur in a non-productive, inefficient, adversarial work environment leading to claims, disputes and costly litigation (Quick 2002).

Jan 1, 2007

By Ludger Suarez-Burgoa

At the Porce III Underground Powerhouse Complex in Colombia, the observational method (Peck, 1969), was used to provide information to an underground wedge and a 2D Finite Element Method numerical models, both used to estimate the mechanical behavior of the hoisting rock mass. The observation process consisted in collecting fault events in the field and in interpreting Multiple Point Borehole Extensometers and Surface Convergence Displacement Points readings. The calibrated models were employed to predict the behavior of the pillars formed between the machine and transformer caverns. The observational method is an important activity during excavation of large openings and provides arguments to understand the rock mass mechanical behavior.

Jan 1, 2008

By S. Cotten

The regulations for current coal mine refuge alternative (RAs) require that there be sufficient life support to sustain survival of the maximum number of RA occupants for a minimum of 96 hours. This minimum duration assumes that rescuers can access the RA through the mine within four (4) days of the onset of the mine emergency. But what if mine rescue teams cannot reach the miners within the RA before the RA air supply is severely limited or exhausted? What could be done to extend the duration of the RA life support capability into the 97th hour and beyond? In addition, what might be done to enable more rapid rescue of the miners if they could not be reached through the mine in a timely manner? This paper describes a systems approach to address the potential need to extend the duration of RA life support beyond current design limits. New capabilities that need to be developed in advance of such a dire need include more reliable emergency communications, highly mobile and efficient drilling rigs, enhanced directional drilling techniques, and a standardized RA external life support interface along with RA internal design modifications to accommodate use of an external supply. The following sections describe the need, intent, and technology gaps associated with each of these capabilities. Government agencies and the mining industry should consider initiation of a program to investigate, design, and develop effective means of extending the current 96-hour time restriction on coal mine refuge alternative life support. The development process should begin with a focused study to refine the overall operational concept, investigate the current state-of-the art of critical technologies, identify specific technology development priorities, and make recommendations for a development program to provide in an organized, efficient, and timely manner a solution for extended refuge alternative life support and occupant rescue.

Jan 1, 2011

By K. Y. Haramy, K. Hanna

Early identification of adverse geologic conditions and high stress concentrations during the high-speed extraction of coal using modern mechanized longwall systems is a major challenge facing the mining industry. Often, unexpected geologic anomalies that affect rock mass quality are encountered more rapidly, leaving the mine operator with insufficient time or information to deal with the changing ground conditions. The RockVision3D™ seismic tomographic system, developed by NSA Engineering, Inc., offers substantial benefits over conventional geologic/stress-detection methods and has been used successfully in coal mines worldwide. Tomographic images, produced economically and in near-real time, are easy to interpret, allowing mine operators to deal with potential hazards on a day-to-day basis.

Jan 1, 1999

By William A. Macaitis, Frank E. Dalton, Leo R. DiVita

The Metropolitan Water Reclamation District of Greater Chicago's Tunnel and Reservoir Plan (TARP) is a multi-purpose urban public works project with a total cost of $3.7 billion. Currently 51 miles of TARP tunnels are completed and operational and 34 miles are under construction. The excavated TARP tunnels have been constructed in rock utilizing 29 tunnel boring machines, ranging in size from 6.5 to 35.3 feet in diameter.

Jan 1, 1993