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By S. M. Hossaini, M. Ataei, H. Moosavi

The abstract highlights the importance of pillar stability in underground coal mines and the influence of rock mass strength and joint orientation on pillar behavior. The study employs numerical modeling using the distinct element code (UDEC) to investigate the impact of these factors on pillar stability. The research considers different joint orientations and varying rock mass strengths, analyzing parameters like stress distribution, displacement, and failure patterns. The findings reveal that both joint orientation and rock mass strength significantly affect pillar stability, with specific combinations leading to reduced safety factors and increased deformation. The study concludes by emphasizing the importance of considering these factors in pillar design for safe and efficient mining operations.

Apr 4, 2022

By W. Edwin Dill

For the mining industry, the Internal Revenue Code and regulations offer a range of choices in arriving at the allowable depletion. Each case is essentially unique. Two prerequisites can optimize these opportunities: communications between the mining company's tax specialists and its technical staff; and an understanding of IRS definitions. For the latter, a logical starting point is consideration of exploration and development, since they precede production and depletion is unallowable prior to production. Criteria for selecting engineering and accounting options for exploration and development indicate the necessity of interaction between these company functions to achieve the most favorable tax position.

Jan 1, 1982

By Frank E. Kottlowski

Widespread high-calcium (HC) limestones in New Mexico and adjoining areas, are low in magnesium, but some units include shale interbeds that would be deleterious for usage in sulfur removal. In southwest New Mexico, southeast Arizona, and adjoining parts of Mexico, limestones in the thick Mississippian Escabrosa, Pennsylvanian-Permian Horquilla, and Cretaceous U-Bar units are HC as are strata in the Mississippian Lake Valley, Pennsylvanian formations, Permian Hueco, and parts of the Permian Capitan Limestone of south-central and southeast New Mexico and west Texas. In north-central and central New Mexico, many limestones in the Pennsylvanian Madera Formation are HC as are some of the Cenozoic travertines. In northwest New Mexico, where the present-day mine-mouth coal- fired power plants occur, there are no HC limestones, but to the north in southwest Colorado some beds of the Mississippian Leadville Limestone and Pennsylvanian Hermosa Formations are HC. HC limestones considered contain at least 95 percent calcium carbonate and less than 3 to 5 percent magnesium carbonate. Limits for other impurities are alumina, 1 percent; silica, 2 percent; sulfur 0.05 percent; phosphorous, 0.02 percent; and iron oxide, about 1 percent. Chemical and physical requirements differ slightly depending upon the ultimate use.

Jan 1, 1995

By C. Heckman, M. S. Moats, A. Luyima, W. Cui

"Chloride ions and their interactions with two organic smoothing additives – Cyquest® N-900 and HydroStar® 4208 – during copper electrodeposition were explored using cyclic voltammetry and electrochemical impedance spectroscopy. The results revealed that chloride ions, up to a concentration of 40 mg/L, depolarized the copper deposition reaction. A combination of chloride ions and Cyquest N-900 inhibited the depolarization reaction during copper electrodeposition. It is proposed that the chloride ions acted as bridging ligands between copper and Cyquest N-900. Addition of HydroStar at a concentration of 2.5 mg/L depolarized the copper deposition reaction when no chloride ions were present. This behavior did not change with the addition of chloride ions at the concentrations tested, indicating that chloride ions and the polysaccharide do not interact.IntroductionElectrowinning is a major production method used to obtain high-purity copper. In modern tankhouses, copper is electrodeposited onto stainless steel blanks and then stripped, washed and bundled for delivery. Significant improvements in the quality of electrowon copper have been made over the last few decades. Additives, temperature, current density, electrolyte concentrations and agitation are known to influence the quality of copper electrodeposits (Jenkins and Eamon, 1990).The influence of chloride and organic additives on copper electrodeposition has been the subject of considerable research. The addition of small quantities of chloride and organic additives has been recognized to significantly improve the properties of copper electrodeposits. These additives are critical in the prevention of dendrite growth and the production of smooth, dense cathode deposits.Chloride ions have been reported to catalyze the copper reduction reaction and assist in the production of uniform deposits (Lakshmanan et al., 1977; Sun and O’Keefe, 1992). Moreover, it is generally agreed that chloride ions depolarize the copper deposition process at low (several millimolar) chloride concentrations. This is because chloride ions catalyze the reduction of copper (II) ions to copper (I) ions (Cu2+ ? Cu+ + e-) in the rate-limiting step of this process (O’Keefe and Hurst, 1978; Ilgar and O’Keefe, 1997; Hebert, 2005; Shao, Pattanaik and Zangari, 2007)."

Jan 1, 2016

By A. H. Baldo

Covers a very broad spectrum of problems and solutions. The problems are multitudinous and their solutions are sometimes simplistic, sometimes ingenious and sometimes within a very broad interpretation of the law. However, one thing is quite certain: the problems and their solutions will have a direct impact upon corporate and personal well being. First of all, why does one mine in a foreign land? Since the Bronze Age, when ancient man discovered the metallurgy of copper, tin and zinc, intrepid souls have been wandering afield searching for and exploiting those mineral deposits which would create wealth and security for his city-state or community.

Jan 1, 1981

By Xin Jingmin

The present trend toward concentration of mining activities into fewer sections of a coal mine and application of automation and remote control technologies favor utilization of the longwall mining method. Longwall mining also offers the potential for improving safety and productivity, better ground control and higher levels of recovery. The production potential of a longwall operation is determined by the interaction of several factors including the rate of face advance, the thickness of extraction, the speed of cutting and hauling equipment, the physical dimensions of a longwall panel, and the reliability and availability of the equipment. Some of these factors are dictated by the environment in which the extraction process is to be undertaken. Some other factors, however, can be manipulated in order to optimize the production of the system. The objective of this paper is to develop a stochastic model to simulate the production operations in longwall mining. The activities and parameters that affect the production potential of the longwall operations and the relationships between the activities are identified. An attempt is made to verify these relationships through the use of existing data. The model is then used as a computer simulator to investigate the effects of various activities and parameters on the production capacity of a panel.

Jan 1, 1983

By Russell C. Drew

The United States has long been recognized for its ability to marshall the many tools of its scientists and engineers to meet national threats or crises. Two major World Wars, the Dust Bowl, the Soviet Missile threat, Sputnik, and more recently the Energy Crisis have stimulated military weapons development, massive land reclamation and water management programs, NASA, and the Space Program, Project Independence, and soon a new agency, the Energy Research and Development Administration. While our record of successful responses to these major national concerns lends support to the expectation that we will succeed in dealing with the current energy problem and potential future crises as well, the crisis mode of response is becoming increasingly wasteful of funds and human and natural resources. This waste, while always of a concern, is a more important factor than previously because of the accelerating pace at which the world has been shrinking, relatively, in comparison to its human population and that population's increasing demand for resources, both renewable and nonrenewable. If present growth patterns continue, in the year 2000 there will be two people to feed, clothe, house, and satisfy for every one person that existed in 1970. On a finite planet, with finite land areas, limited resources, and only partial understanding of the means by which future problems can be addressed, one of the major threats to mankind will be scarcity and one of our major challenges will be better management of our resources. The challenge will be to guide Federal investments in R&D that are of sufficient magnitude and in the proper

Jan 1, 1974

By D. M. Thayer

Laboratory and pilot plant investigations have indicated that copper recoveries of 50% can be achieved with fine grinding and flotation of a copper reverberatory furnace slag, Microscopic and microprobe studies indicate that the recoverable copper is in the form of matte, chalcocite, and metallic copper; the percentage of copper in particles appearing to be copper-free was from 0.23 - 0.54%.

Jan 1, 1969

By Alizeibek Saleimen Nader

The intensive use of computers for mineral application at Serrana's phosphate mine in Jacupiranga, State of Sao Paulo, Brazil, began in the late seventies. The early hardware and software available are described in sufficient detail to allow comparisons between that solution and the new one, based on a personal computer and a new software package - PC MINE SYSTEM from GEMCOM SERVICES INC - that provides full color graphics capabilities plus mine design and planning tools. The process needed for adaptation to the new technology' and its impact on SERRANA S.A. DE MINERACAO are described. Finally, future enhancements to the System and mine control and planning are focused.

Jan 1, 1989

By Frederick P. Agterberg

It can be useful to model the mean grade values for a metal in mineral deposits containing that metal as representing the extreme value tail of a lognormal frequency distribution for the concentration values of the metal in rocks of all types. Results for copper and zinc in the Abitibi area of the Canadian Shield are compared to results previously obtained for the Canadian Appalachian Region. The lognormal model is also applied to a set of 162 large gold deposits in the Abitibi area. In the second part of the paper, 1311 large and small gold deposits in the Abitibi area are modelled as discrete events. By means of a newly developed spatial clustering model it is possible to predict the variances of random variables for frequencies of deposits in cells of different sizes.

Jan 1, 1979

By Jason Saldanha, Andrew Evans, Jonathan Baber

"INTRODUCTION The need for a new road crossing at Silvertown is the result of three key drivers:- •,Severe congestion and delay at the Blackwall Tunnel and surrounding road network; •,A lack of network resilience and reliability resulting from a lack of alternative road crossings in east London and the impacts of unplanned closures; and •,The need to support substantial economic development in east and south-east London (jobs and homes) These drivers directly informed the main objectives for a road-based river-crossing solution. The traffic-related problems at Blackwall Tunnel are long-standing and before Transport for London (TfL) assumed control for the strategic road network in London in 2000 the Department for Transport (formerly Dept of Transport) had investigated various relief options including a third tunnel bore and new bridge. This resulted in a new crossing alignment being safeguarded (by direction of the Secretary of State for Transport) and this was refreshed in 2001 in favor of TfL. In recent years (since 2009) TfL as part of the East London River Crossings Programme has undertaken detailed optioneering and feasibility work to address the above ‘need’. This led to the conclusion that a new road tunnel would offer the best solution in preference to bridge, ferry or demand management options. In 2012, in response to a formal request by the Mayor of London, the Secretary of State for Transport confirmed a new road crossing at Silvertown as a Nationally Significant Infrastructure Project (NSIP) by Section 35 direction under the Planning Act 2008. This NSIP designation meant that TfL as scheme promoter must comply with the National Rail and Road Networks National Policy Statement (NNNPS) and must seek the necessary powers to build and operate the crossing by means of a Development Consent Order (DCO) under the Planning Act 2008."

Jan 1, 2016

By Barry R. Doyle, Emma C. Ross

This paper presents a 20-year global account of tunneling in gassy ground demonstrating high probability of schedule delays, cost overruns, worker injuries and fatalities. Causes of these failures are systemic. Gas is seldom characterized in terms relevant to design of effective ventilation systems. Control measures deployed in tunnels are often based on outdated industrial safety codes. A change in approach is needed. This paper describes how to perform a desk study to determine if field investigation for gas is warranted, and lists the content of an effective characterization of gas in a geotechnical report.

Dec 1, 2022

By B. J. Arnold

With the passing of the 1990 Clean Air Act Amendments, many utilities are opting to switch to lower sulfur coal to meet new SO2 emissions requirements. This lower sulfur coal may be from new suppliers or it may be from current suppliers that modify existing cleaning plants or build new plants to produce this higher quality coal. New, sophisticated coal cleaning simulators are useful tools for optimizing cod cleaning circuit operating parameters to maximize the production of clean coal that meets more stringent specifications for SO2 emissions potential. The examples in this paper were developed using the Coal Cleaning Simulator (CCS), running under ASPEN PLUS™, that was developed under a Department of Energy project cosponsored by the Electric Power Research Institute. With advanced sensitivity analysis and optimization features, CCS allows a quick, efficient, cost-effective review of coal cleaning plant performance to meet current production goals and to plan future changes in plant operating parameters or circuitry configurations.

Jan 1, 1995

By Richard R. Klimpel, Basil F. Fee

This paper summarizes the status of a series of new chemical reagents developed with the explicit goal of expanding the capabilities of existing froth flotation processes as well as allowing for new solid/solid separations to be undertaken that are not now feasible with flotation. The first portion of the paper briefly outlines the theory and motivation behind the development of each new reagent family. 'The second portion of the paper deals with specific laboratory examples of some separation systems studied to date.

Jan 1, 1993

By Madan M. Singh

Section 516 of Public Law (PL) 95-87, commonly known as the Surface Mining Control and Reclamation Act of 1977 (SMCRA), requires that underground coal mine operators must "adopt measures consistent with known technology in order to prevent subsidence causing material damage to the extent technologically and economically feasible, maximize mine stability, and maintain the value and reasonable foreseeable use of such surface lands, except in those instances where the mining technology used requires planned subsidence in a predictable and controlled manner..." Implied in the constraints of Section 516(b)(1) of SMCRA is a determination of what constitutes "material damage" to surface structures, renewable resource lands, and the capacity for sequential land use following underground mining. The authors have already briefly addressed the subject of damage criteria in relation to surface structures (Bhattacharya et al, 1984). In this paper, an attempt is made to provide quantitative guidelines to ascertain material damage to renewable resource lands, although the data available to establish these criteria are considerably more limited than is the case for surface structures. Besides, many more variables influence the severity of the impact at a given site, making the task of assigning stringent ground movement limits even more complex. This often necessitated use of professional judgement and occasional reverting to a qualitative approach. Hence the reader is cautioned at the very outset that the quantitative limits presented herein are approximate and are primarily intended to serve as rough guides for ascertaining the extent of damage to the renewable resource lands under consideration, and that depending on site-specific conditions the actual damage incurred may differ significantly from that predicted by the proposed criteria. The authors, however, feel that the criteria suggested are somewhat conservative, but realistic. The actual damage observed should generally be less severe than predicted by these criteria. It may also be clarified here that the term "subsidence", as used in this paper, implies the total phenomenon of surface and subsurface effects associated with the mining of minerals and not only the vertical displacement of the surface as is sometimes inferred in the literature.

Jan 1, 1984

By Campbell J. McKenzie

Following on from the successful completion of three exploration programs and the discovery of two new inactive Seafloor Massive Sulphide (SMS) deposits within New Zealand?s Exclusive Economic Zone (EEZ), Neptune is now poised to take the next step from explorer to developer. Neptune considers that commercialization of SMS deposits represents the future of the mining industry, providing a new source of metals to the world economy, and enabling host countries to benefit from this new industry. Neptune recognizes that marine biodiversity is among the greatest treasures of New Zealand. The geological isolation, range and complexity of habitats, and a number of major ocean currents that influence New Zealand have created diverse marine communities. Neptune, recognizing both the environmental importance of marine biodiversity and the value it provides to all New Zealanders has made commitments to ensure sustainable development. There are many unanswered questions regarding how the marine environment may be affected by SMS development, however best practice environmental management is a key aspect of the Company?s approach to our activities and the code for ?Environmental Management of Marine Mining? prepared by the IMMS has played a part in this approach. Neptune has close relationships with the scientific community to ensure that appropriate environmental strategies and plans are developed in order to minimize the effects of our activities on the environment.

Jan 1, 2008

By Lawrence Adler

The properties of a geologic mass may be considered from a resource or an engineering viewpoint. The primary engineering applications include ground control, excavation, bulk handling, and hydrology. This study will focus upon these areas in descending order. For an adequate geologic description, data is necessary on the following components: (1) the intact rock, (2) geologic structures, (3) contained fluids, and (4) existing pressures and temperatures, see Table 1. This information, combined with the engineering specifications, provides the basis for a formal geotechnical analysis as illustrated in Figure 1. For a structural analysis it is essential to establish the mechanical properties of the material composing the structure. This material, termed the "rock mass," consists mainly of the first two geologic components, the intact rock and geologic structures (Figure 1) Consideration of fluids will be subordinated to their role as chemical agents affecting the mechanical properties. The existence of pressures and temperatures generally lies beyond the scope of this study.

Jan 1, 1973

By C. O. Hamilton

Poor plant start-up performance is usually blamed on poor design and unsatisfactory equipment. But, in most cases, the real cause of poor performance is inadequate preparation for operations and maintenance. Inadequate maintenance preparation, unlike inadequate operations preparation, will not immediately manifest itself in a new plant. However, not taking advantage of the window of opportunity afforded a new plant to organize the maintenance operation ensures that the new equipment honeymoon is unexpectedly short. Also, once a plant has entered a “breakdown mode,” it is extremely difficult to turn around.

Jan 1, 1991

By W. H. Davitt

One might ask why someone like myself, involved in the determination of taxes, should be speaking at a "cost engineering" session of a national engineering society. While it is true that taxes, especially income taxes, whether they be federal, state, or local, are not usually thought of as a "cost" of doing business, it is equally true that these tax costs do reduce the distributable profits just as much, as the cost of power, supplies, or labor. Therefore, the consideration given to taxes is often as important as that given to other costs. Hopefully yea will recognize that, within certain limits, taxes can be controlled to an economic advantage. That question may then lead to another question: What does the amount of taxes have to do with me? I'm an engineer or manager; not an accountant or a lawyer. If I may take a few minutes of your time, I might be able to present in a brief discussion some interesting facts that will provide the answers to those questions. My discussion will be directed mainly to Federal taxes. However, much of it will be applicable to state and local taxes, also.

Jan 1, 1973

By Kathy Kalenchuk

To develop strategic and tactical strategies to manage seismic hazard in a safe and economic manner, it is necessary to understand the spatial and temporal distribution of mine wide seismogenic behavior. Global mine-scale numerical stress modelling provides a means to forward predict seismic susceptibility thereby facilitating informed decision making for the development and implementation of strategic and tactical risk mitigation measures. To make forward predictions of hazard susceptibility using global stress models with reasonable confidence, it is necessary to rigorously calibrate numerical stress models to the observed history of ground reaction. This paper demonstrates quantifiable methods for calibrating numerical models and developing probabilistic prediction criterion using seismic data. The appropriate applications of model inputs (including boundary conditions, constitutive models and material parameterization) specific to global mine-scale modelling are also discussed. Lastly, this paper demonstrates how the calibration process adds value not only to informed decision making, but also to the improved understanding of site geomechanical conditions; including enhanced identification of geotechnical domains and mechanical indicators required for seismic mechanism domaining.

Apr 26, 2022