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By Mark W. Cadwallader

Heap leach mining requires liners in order to contain leaching solutions for both economic and environmental incentives. The use of HDPE geomembrane liners for heap leaching is discussed in this paper. Comparison is made to clay liners, with inclusion of economic considerations. Several heap leach projects incorporating geomembranes are discussed.

Jan 1, 1987

By B. M. Moudgill, T. V. Vasudevan

Marine sedimentary deposits account for 80% and igneous deposits 17% of the total world output of phosphate rock. The phosphate mineral is well crystallized and exhibits a greater floatability in the igneous deposits than the sedimentary ores. Both silicates and carbonates contribute the major gangue associated with the sedimentary ores. Although removal of silica from sedimentary phosphates by froth flotation has been in practice for several decades, with the depletion of high-grade reserves, new attempts are being made to improve the efficiency of current silica removal technology and to develop new processes for beneficiation of phosphate ores associated with the carbonate gangue. In this paper, recent developments in processing of sedimentary phosphate ores containing carbonate and silica gangue are discussed.

Jan 1, 1987

By W. B. Beerbower

Resin bolting has enjoyed wide acceptance for coal mine roof support. Beginning in 1973, the first year of significant resin bolting in coal mines, we estimate that 2.5MM resin bolts were installed. This grew to 7MM resin bolts in 1974 and 13MM in 1975. Resin bolts are currently being used in over 300 coal mines throughout the major coal producing areas of the U.S. and barring major work stoppage we expect more than 17MM will be installed in 1976. Although not a cure-all, the number of unintentional roof falls occurring in many mines has been dramatically reduced as a result of converting to this "new" method of support. 1 The improved anchorage strength of resin bolts provides better roof support. (Slide #1) This anchorage strength provides a mechanism to resist changing roof stresses along the entire length of the fully grouted resin bolt, thereby assuring stabilization of rock strata over long periods of time. The ability to resist roof displacement is borne out by readings obtained from strain gauged bolts. These findings can be summarized as follows.2

Jan 1, 1977

By Jan K. Wolski

Detection of the air recirculation branches within a large ventilation network may be difficult, therefore a PC computer routine has been developed to perform this task in an efficient and reliable manner. This paper describes the method illustrated using a network with complex multi-recirculation circuits. The fact that only the air flow directions and not the flow rates are used in calculations is of some interest. The air recirculation during a real mine fire is demonstrated using the PCVENT program, whose version 4.0 includes current information about any recirculation branches during network calculations or during a fire simulation. This paper also discusses some transient problems related to air recirculation, and gives examples.

Jan 1, 1993

By L. Micale

In May of 1986, the Arizona Legislature passed comprehensive environ-mental legislation called the Environmental Quality Act (the Act). The Act focuses on ground water protection and addresses drinking water quality, aquifer protection standards, requirements to apply technology to reduce discharges, and a state Superfund program.

Jan 1, 1988

By F. M. Doyle, J. P. Dwyer

Introduction The mining industry has a poor public image. It is often perceived as a despoiler of the landscape and a polluter of the environment, and there is little recognition of societal needs for the raw materials and fuels that this industry produces. There are many reasons for this poor image, but an important one is that a substantial number of mining operations have caused significant damage to the environment. Many of these operations, particularly those that now are abandoned, continue to have an adverse impact, principally in the form of water pollution.1 In some cases, the damage caused by this pollution extends well beyond the immediate region around the mine. Chemical contamination of ground and surface waters can, and does, occur in nature when these waters flow through or over undisturbed, mineralized rock masses. However, the problem is greatly exacerbated by mining because the mining activities increase, by several orders of magnitude, the permeability and the surface area of rock that can be contacted by percolating water. Water flowing through either the mine workings or the waste rock dumps becomes contaminated. Pollution can also arise if leachate from tailings ponds enters either groundwater or surface waters. This leachate may contain chemicals used in processing the ore. The magnitude of the threat posed by mining wastes depends on the type of minerals in the deposit, and on the chemicals used to process the ore. The magnitude of the threat also depends on two other, site-specific factors. One is the volume of water flowing into the mine and through the dumps, which depends on rainfall patterns, topography, and whether the mine workings are surface or underground. The other is the proximity of the pollution source to groundwater or surface waters, which depends on both the climate and geology. These factors influence the concentration and the quantity of polluted water forming and reaching the receiving water. Mining activities present a potential problem of enormous scale. Vast amounts of rock are mined each year2 and, as noted above, substantial problems have arisen at some mine sites. These problems are usually exceedingly costly to address, and it is imperative that these mistakes not be repeated. There are indications that we can accomplish this goal; we now better understand the processes that cause pollution and have methods to prevent or contain it. In addition, in the past few decades society has started to recognize the need for all industries to operate in a manner that maximizes the health and safety of workers and the public and minimizes adverse environmental impacts. A variety of recently enacted federal and state laws regulating public health and environmental hazards reflect the increasing concern over these issues. Many statutes, such as the federal Clean Air Act and the Clean Water Act, encompass activities undertaken by the mining industry. Other laws, such as the Surface Mining Control and Reclamation Act, have been written to regulate specific hazards posed by this industry. At the present time, the federal government. through the Environmental Protection Agency (EPA), and several state governments, are preparing new regulations specifically tailored to control the disposal of mining wastes. Given the magnitude of the potential environmental and health risks posed by disposal of mining wastes and the regulatory costs to the mining industry (both of which are due to the tremendous volume of waste generated), it is especially important that regulators have a good understanding of the different types of mining wastes and the risks they are likely to pose in various geographic and climatic circumstances. Only then can a regulatory program be designed with suitable procedures and substantive criteria to protect the environment and ensure compliance, while avoiding unnecessary or wasteful expenditures. California has long enjoyed a large, active mining industry. Today it produces a wide range of mineral commodities. The revenue from production of non-fuel minerals in California ($2.85 billion in 1988) greatly exceeds that of any other state. About a third of this revenue is from the production of inert sand, gravel and crushed stone. However, the remainder is from the production of a wide range of materials. These include boron minerals, rare earths, asbestos, talc and pyrophyllite, and gold. In earlier decades, an even broader range of minerals was produced, including mercury, copper, lead, zinc, and barite. There are acute environmental problems at some of these early mine sites. Because in 1987 the state of California was engaged in a revision of its regulations for mining waste disposal, the legislature commissioned a study by researchers at the University of California at Berkeley to investigate and review: the magnitude of the problem posed by these wastes, • the best feasible control measures available for waste management and disposal, • the problems of abatement and cleanup at so-called "problem" mine sites, • the current regulations imposed on mining waste disposal by various federal, state, and local agencies and the effectiveness of these regulations. This paper summarizes the principal findings from this study (Mining Waste Study, 1988). The lessons from this investigation are likely to be of general interest because of the diversity of mineral products produced, and the wide range of geographic and climatic conditions encountered. The acute problems seen at some of the older mines are typical of the western United States, and teach useful lessons on strategies that should be implemented at new mines to prevent recurrences of these problems.

Jan 1, 1992

By S. Dempsey

Since its passage in 1872, the Mining Law has been modified on several occasions to meet the changing needs of America's society and economy. Despite its evolution, the Mining Law continues to be criticized as outdated. This paper briefly traces the major points in the history and evolution of western mining laws, and reflects on the current status of ongoing discussion to reform the 1872 Mining Law.

Jan 1, 1997

By T. A. Gray

There are several potential large-volume uses for coal ash in mining-related applications that could be environmentally and economically beneficial to mining companies. Actual usage, however, may be constrained by regulations or by perceptions of coal ash and the potential uses. To identify currently allowed uses and to assess constraints to coal ash use in the eastern coal fields, questionnaires were sent to state coal mining agencies to determine their policies on coal ash utilization and to mining companies to solicit their viewpoints on coal ash utilization. Identifying and understanding the constraints will allow for the development of a coordinated and consistent approach to remove or reduce these constraints and possibly allow for increased utilization of coal ash by the mining industry. This paper summarizes the findings of our investigation.

Jan 1, 1995

By G. W. Luxbacher

With the advent of acid rain legislation included within the Clean Air Act Amendments of 1990, a great deal of uncertainty with regard to price, source and production quantities has been cast into the coal market. Powder River Basin and other western coals continue a rapidly accelerating migration eastward, South American coals move into the northern markets, states propose legislation to assist utilities in complying with the new regulations in hopes of maintaining their own coal industries, while some utilities question the long term availability of eastern compliance coal. Any major coal producer must make decisions now to assure their continuing presence in the market place; several companies have adopted a strategy to acquire eastern compliance reserves while others have invested in technology to compete as a low cost producer. This paper discusses some of these options in light of the uncertainties of the market place, from an eastern coal producer?s viewpoint.

Jan 1, 1992

By C. Meyer, J. J. Eidel

Major gaps in understanding hydro- thermal systems remain after a century of studying fossil ore deposits and active geothermal areas. The periodically rejuvenated concept of "stacking" ore deposit types has never been verified by a continuous sample. Basal and marginal regions of both “fossil" and "active" hydrothermal systems normally lie beyond the limits of economic exploration, remaining inadequately exposed. Incomplete scientific under- standing of he vertical transitions clearly limits the efficacy of exploration programs for hydrothermal ores of all types. The Continental Scientific Drilling Committee's (CSDC) Panel on Mineral Resources has defined dedicated research objectives and add-on experiments to industry or government drill holes of opportunity.

Jan 1, 1988

By Thomas V. Falkie

The title of this talk has brought some interesting responses - even before it was written - from different parts of the country. A geologist from the Western U. S, was deeply concerned with recent layoffs in his profession and the employment situation in general and wondered why "the AIME wasn't doing anything for the benefit of its members." A petroleum engineer in Texas said that a group in his field were studying "professionalism" and their professional status and wondered if there were any words of wisdom for him. A mining engineering professor from the East pointed out that the National Science Foundation did not include mining engineering as one of its recognized fields in one of its equipment funding programs. These are just a few examples of reactions received to date, but they serve to illustrate the broad image that the title has meant to various people. Actually the term profession is defined by Webster as "a calling requiring specialized knowledge and often long and intensive academic preparation." The word encroach means "to enter by gradual steps or by stealth into the possessions or rights of another", or "to advance beyond desirable or normal limits." The intention of this paper, as originally conceived and requested by the program chairman, was to combine those two words literally and talk about how the professional standing of mineral engineers is being eroded from people outside the profession. But the amazing preliminary response suggests that it may be timely to broaden the discussion by including some comments about professionalism in general. In the paper the terms "mineral engineer" or "mining engineering" are used frequently, but it should be clearly understood that much of what is said is valid and is intended for all fields covered by SME and perhaps for AIME in general.

Jan 1, 1972

By Olivier Kraft, Olaf Kortz

"Project-specific optimized tunnel boring machines represent the spearhead of technological progress in tunneling because with their use, very long-lasting, high quality tunnel structures in almost any geology, depth and topography can be produced with a high degree of automation. The mechanized excavation of tunnel structures ensures the greatest possible environmental protection during tunneling itself. Professional, systematic and high quality rebuilds and reuse of already proven equipment also ensures maximum efficiency in the use of materials and energy resources. It offers an enormous potential for a highly optimized environmental balance. Here the manufacturers of tunnel boring machines and their users in particular have a duty to ensure transparent, high quality and binding standards in the entire rebuild cycle and in the refurbishment management of innovative tunneling technology. This paper deals with the comprehensive processes with rebuild levels of tunnel boring machines and highlights some exemplarily implemented projects. 1 INTRODUCTION All over the world, the number of tunnel boring machines (TBM) in which equipment rebuilds from previous projects are re-used has increased over the last few years. This text presents the technical and economical aspects of this market development. It also takes a look at the practical implementation of rebuild measures. The ""ITAtech Guidelines on Rebuilds of Machinery for Mechanized Tunnel Excavation"" from 2015 lay down the requirements that the machine manufacturers must meet. 2 ECONOMICAL AND ECOLOGICAL ASPECTS OF RE-USING COMPONENTS The globalization of the construction sector and the consideration of environmental aspects promote an increased re-use of machines and machine components. Nowadays, large-scale construction projects are often carried out by international joint ventures of several individual companies that are established specifically for this purpose. After the completion of the project, the joint ventures are dissolved and they liquidate their project-specific equipment, such as tunnel boring machines. Today, it is much more uncommon for such machines to remain permanently in the possession of construction companies. Joint ventures offer TBMs on the free market, or they exercise contractually agreed repurchase options with the manufacturer. On the whole, this increases the number of re-usable components or complete tunneling systems available on the market."

Jan 1, 2016

By William J. Kohan

Milling has traditionally been considered more art than science. In the last 10 years, significant improvements in process equipment have been made and we are finally taking significant steps toward approaching grinding as a science. Two machines have been at the center of this development. These are the roll press and the high efficiency separator. The former can be considered as a new technology or adaptation of existing i.e. roller mill. The latter is clearly an improvement of existing technology. Other machines have been introduced to a lesser degree and later. Among these are the CKP and Horomill. The purpose of this paper is to provide an over- view of the currently available modifications for operating systems and options for new milling circuits with some comments on their application and history.

Jan 1, 1997

By B. C. Lewis

When John F. Kennedy made this statement, I am sure he was not thinking about the valuation of limestone reserves. However, it is certainly applicable. The objective of this paper is to demonstrate how the discomfort of thought (i.e., the analytical and methodical process performed by a reputable professional) builds the foundation for an opinion that provides assurance as to the value of a property. In its final form, a valuation is nothing more than an opinion. The credence of that opinion is directly proportional to the knowledge of the appraiser and the efforts and judgment extended in developing said opinion. Presented herein are the methodologies for formulating a defensible opinion. Before detailing the valuation process, an overview of the limestone industry is presented along with some historical parameters relating to the industry. Secondly, the most widely used valuation methodologies and a brief discussion of each are presented. Two case studies are then presented, which review actual valuation studies. The paper concludes with how the valuation process should be published in a report format that is defensible from a legal standpoint, bankable from a financial standpoint, and decipherable from a layman's standpoint.

Jan 1, 1989

By Vaughn Astley, Hassan El-Shall, Ponisseril Somasundaran, Regis Stana, Patrick Zhang

In the past, when phosphate rock quality was good, few paid attention to any of the impurities or other qualities associated with phosphate rock. In general, they had little or no effect on the ability to make the phosphate products for the market. However, as phosphate rock quality declined, it was apparent to the rock consumers that the individual impurities had a significant impact on their processes. FIPR is presently funding an analysis of operating plant data to determine the range of the effects of rock impurities on production plant performance. The study will not be completed until 2002. IMC has agreed to share some of the information they had developed in the early 1990s.

Jan 1, 2002

By D. D. Banerjee, S. K. Kawatra, T. C. Eisele

A high calcium fluidized-bed combustor ash was shown to be an effective binder for iron ore pellets at dosages of 1 % to 2% of the magnetite concentrate weight. Magnetite pellets that were between 1.1 and 12.7 mm (7/16 and 1/2 in.) in diameter were produced with dry crushing strengths greater than 22.3 N (5.0 lb-force) per pellet, which is comparable to the results produced using conventional bentonite binder. The effectiveness of fly-ash-based binders was considerably improved when calcium chloride was added as an accelerator. The addition of calcium chloride at a rate of 0.1 % to 0.2 % of the total powder weight increased the strength of the dried pellets by as much as 22 % compared to the strength of pellets made using fly-ash without accelerators.

Jan 1, 1999

By H. Ouellet, J. Paraszczak

The pneumatic jackleg drill remains a widely used tool in development and production drilling in many small-scale and narrow-vein underground mining operations in North America. Several drawbacks of this technology (unsatisfactory drilling rate, noise, vibration, presence of oil mist, etc.) and the successful introduction of water-powered jackleg drills in South Africa have stimulated the interest of many mine operators. The performance of both drill types have been tested in a mine site in Northwestern Quebec, Canada. Results of the testing of penetration and advance rates as well as environmental aspects are presented. They show a superiority of water-powered drills, even though the difference in performance is less significant than that reported from South Africa. Further research avenues are proposed to better evaluate the potential of water drilling technology in North American metal mines.

Jan 1, 1995

By R. J. Gochin, M. A. Diaz, M. L. Court

Single impact breakage tests have been carried out on samples of alumina in carefully controlled atmospheres consisting solely of nitrogen gas and water vapour. The results indicate a statistically significant increase in the surface area of the progeny particles as relative humidity rose to 50%. The majority of this increase was found to occur under conditions when adsorption was a monolayer or less. The results are consistent with the theory of surfactant-induced strength reduction of materials proposed by Rehbinder and Westwood. There are important implications where single impact tests are used as part of a design methodology for comminution machines. In most procedures relative humidity has not been a controlled variable.

Jan 1, 1995

By L. A. Morley, S. C. Gambrell

Behavior of a jour-leg shield design used on a soft floor in an operating longwall system is presented. The shield examined in this study was constructed having a split base and a split caving shield. Attention is focused on other-than-normal loading on the canopy and its effect on deformation of the lemniscate links. Examples of the magnitudes of typical bending and twisting deformations are given. Schematics of the canopy, caving shield, and lemniscates showing important forces and moments are presented. Approximate minimum values of the forces and moments required to produce the deformations are calculated based on the mechanical properties of the material. The need for use of more inclusive three-dimensional design techniques is demonstrated.

Jan 1, 1991

By Tracy E. Barnes

The process of computerized reserve estimation consists of assuming a model of the spatial continuity of a deposit and then, working within the assumed model, estimating the grade and tonnage of the deposit. The basis for geostatistical analysis is a statistical definition of this continuity or the variogram. The true variogram is essentially impossible to define. So an experimental variogram is defined from the sample data and kriging proceeds assuming that this experimental variogram is a good approximation of the true variogram. Therefore the closer the experimental variogram is to the true variogram the better the estimate will be. Realizing that the variogram is nothing more than the definition of the spatial continuity of the deposit, taking the known geologic continuity of the deposit into account will give a superior variogram. The use of known geology is a widely recognized necessity for good structural analysis of a deposit, but is rarely fully incorporated into the structural analysis.

Jan 1, 1982