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By M. E. Poad

In 1986, a cooperative effort by the Homestake Mining company, the U.S. Bureau of Mines and the University of Utah was initiated to determine shaft stability while recovering high grade ore in a nearby pillar. Premining finite element simulations indicated the shaft would remain in elastic ground. Six years have elapsed and, despite some initial concern during the first lifts, it appears that the bulk of the original reserve will be safely and profitably recovered. An integrated application of rock mechanics tools from laboratory testing through numerical modelling to mine measurements and observations contributed substantially to the operational success of the project.

Jan 1, 1994

By R. K. Davey

Before the introduction of computerized procedures, mineralization modeling (compilation of level maps), ultimate pit studies, ore reserve compilations, and long-range mine planning all were performed manually. In fact, much of the basis for today's computer programs was derived from manual procedures and actual experience of mining engineers and geologists.

Jan 1, 1979

By Rahul Bhaduri

Mercury levels in Twin Creeks Vista pit ore (previously Chimney Creek, North pit ore) increased substantially since plant start-up in November 1987. Consequently, modifications were necessary to minimize industrial hygiene hazards and potential operational problems. The original plant design included mercury control measures. With progressive increases in mercury levels, the issue had to be re-addressed. Modifications to operational practice, industrial hygiene and management philosophy will be discussed. Additionally, a detailed examination of the mercury vapor suppression system currently employed at Twin Creeks will be presented.

Jan 1, 1994

By C. M. Jones

The training program developed at Sierrita over the last twelve months has led to several significant improvements in both safety performance and productivity. Our most easily quantified results have been in truck productivity, where we have also experienced a 6% decrease in truck cycle times. We feel this is due to increased skill levels and awareness on the part of our operators due to our new training effort. The cycle time improvement has resulted in an increase in Truck productivity of 6%. Costs associated with productivity training have been $160,300. This includes program development and execution costs, as well as lost productivity during the training itself. These costs are offset by $1,400,000 in savings directly attributable to the increased skill levels of our technicians due to our training effort. As such, this represents a solid, high return investment at Sierrita.

Jan 1, 1998

By P. Petropoulakis

Computer technology in the mining activities of our company has been applied in the last decade. In this presentation the experience gained by applying this computer technology in mining spescific applications are reported. Attention is given to the problems phased out and to the methodology used for software selection, centralized and decentralized development, data processing personnel and end users training and support. The paper concludes with a report of the first results obtained and a look at the future developments of the system.

Jan 1, 1989

By Jr. Neudecker

Rock melting technology can provide in-situ glass liners in nuclear waste package emplacement holes to reduce permeability and increase borehole stability. Reduction of permeability would reduce the time and probability of groundwater contacting the waste packages. In-creasing the stability of the storage boreholes would enhance the retrievability of the nuclear waste packages. The rock melting hole forming technology has already been tested in volcanic tuff similar to the geology at the proposed nuclear waste repository at Yucca Mountain, Nevada.

Jan 1, 1989

By H. B. Weaver

The development of a method to manufacture diamonds has been rated as one of the out- standing scientific achievements of our time. The story is both interesting and significant. This paper will quickly review history of diamond and manufactured diamond. Next, it will discuss manufactured diamond as a product -- how good is it -- and what is the significance of this scientific achievement. And finally, present a few thoughts about the future of this technology and this product. For centuries, diamond was found only in alluvial deposits, primarily in the Golconda fields of India. As a result, man knew nothing of the process by which the stones were formed. In 1860, diamonds were found in South Africa under completely different conditions. Here, for the first time, they were found in volcanic pipe -- their mother ground. These volcanic pipes are roughly cylindrical columns of rock which go deep within the earth. The theory as to the formation of diamond was presented by the geologists in that era. The theory states that molten rock was thrust up through a layer of carbonaceous shale where it picked up the carbon necessary for diamond formation. It was generally agreed that diamond was formed approximately 240 miles below the surface of the earth, thus indicating that extremely high temperatures and pressures were involved.

Jan 1, 1964

By D. V. Bush

The economic application of real time computer control can be broken down into 2 broad areas of concern. The first would be in gaining the most efficient utilization of energy. The second would be in improved product quality. This paper will be primarly concerned with the first area of efficient energy utilization as that area has the greatest effect on costs and thus net profits. Most process control strategy attempt to achieve the greatest comminution with the least amount of energy thus maximizing efficiency. A more direct approach to energy control involves a total mine and mill energy management system. In most cases these systems have an ability to achieve a very short payback period with the greatest return on investment.

Jan 1, 1986

By P. K. Muduli

The number and the type of trucks and shovels are two important factors in determining the optimal design parameters of an open-pit mining system. Characteristics of trucks' arrival and service-time distributions determine the performance measures of a truck-shovel system when it is modeled as a closed queuing network. In all of the previous analytical queuing studies of truck-shovel systems, trucks are assumed to be identical with respect to their arrival and service-time distributions. This assumption, although desirable for reducing computational difficulties, causes either underestimation or overestimation of the performance measures depending on the number and type of equipment used in the model. The relative error in performance measures could be significant when the number of different types of trucks and shovels is large. In this paper an analytical method is proposed to model the truck-shovel system as a multiple-chain closed queuing network. This approach would provide the capability of estimating system performance measures for planning purposes when the truck fleet is not necessarily composed of identical trucks. An example of truck-shovel systems is discussed to show how the incorporation of different types of trucks does affect performance measures.

Jan 1, 1996

By D. W. Hendrickson

Cleveland-Cliffs views the mining process as ex- tending from mine planning to cargo loading including auxiliary systems such as materials handling and plant utilities. Process automation is recognized as an area that can provide significant improvement opportunities with less capital requirement than major flowsheet modifications. This article discusses the development and results of a strategy to allow and promote implementation of process-automation improvements at individual mines based on their economic priorities, taking advantage of common systems and concepts for use at multiple mines where practical. Specific process-control upgrade projects at Hibbing Taconite Co. and the Empire Mine are reviewed.

Jan 1, 1998

By R. L. Lewis

A simple method for estimating the steady-state water quality of a pit lake is presented. The steady-state concentration of a conservative chemical constituent in a pit lake is shown to be a simple function of the inflow rate, the evaporation rate and the inflow concentration. An analytical method is presented for estimating the equilibrium ground water-inflow rate for use in water-quality predictions. The time required to reach chemical steady state is estimated using an iterative mass-balance model. Mine operators should find the methodology useful for planning and screening regulatory applications where conservative estimates of pit lake water quality are desirable.

Jan 1, 2000

By K. S. Eric Forssberg, Lennart Ryk

The paper discusses coal utilisation in Sweden. All hard coals have to be imported from other countries. Peat from domestic sources is used as a complement. Environmental legislation and taxation on fuel and emissions are severe. This situation affects the procurement, preparation, handling and use of coal. The paper presents: • R&D projects concerning deep cleaning of thermal coal. • Handling and treatment of coal used in PFBC boilers and for blast furnace injection • Dust prevention for coal and peat briquettes. Procurement of coal emphasising quality and environmental issues.

Jan 1, 1995

By G. W. Heunisch

The properties of Neutra-Fix® and Neutra-Ment®, two new lime substitutes for treating acid mine drainage (AMD), have been compared with lime and Allcament®, two products presently in use for AMD treatment. The two new products are basically dolomitic byproducts and produce sludges that are more compact than those from lime. Sludge settling rates are faster than lime with iron concentrations after 24 hours that comply with Environmental Protection Agency (EPA) regulations. Material utilization and optimum pH are reported.

Jan 1, 1988

By Spencer R. Titley

"For his pioneering contributions to the understanding of the geology of porphyry copper systems" Recipient Of The 1997 D. C. Jackling Award SPENCER R. TITLEY Introduction The subject of this lecture, a late century perspective on porphyry copper geology, is one of current interest and importance as the search for these ores remains intense. It is presented in the belief that an appreciation of our present understanding of the subject requires it to be viewed historically, thus providing a basis for evaluating appropriate directions for continued study. At the outset, it is important to note that the technology of mining and extractive metallurgy has developed ore from these low grade orebodies, starting with D. C. Jackling, and has continued to create them as copper grade and price have diminished. But the continued search for them is a geological problem that responds to growing expectations of people and societies; exploration based upon ever increasing knowledge of the habits of the ores has been very successful. This is the story of evolution of geological thought and practice in porphyry ore search across an interval of time beginning with the bulk mining of "low grade" copper ores at Bingham and ending with late Century concepts. "How did we get here?" The lecture concerns the ideas of many different people. The ideas and events discussed reflect a bias on North American thought, where the great low grade orebodies were first recognized as such and where many of the basic geological ideas were developed. A very great number of geologists have contributed to this understanding. In no sense is it meant to minimize the contributions to the story that have evolved in the study and mining of ores of the Andes, whose development and expansion has been nearly synchronous with that in North America - nor to minimized comparable contributions made in the late century from studies of the newer discoveries of deposits in other regions, especially the southwestern Pacific regions. In expansion of this topic, I have found that many important concepts are marked by appropriate publication but some are not, or I have not been able to discover documentation. Many notions appear to have become conventional knowledge without publication, mostly being geological viewpoints developed synchronously from similar observation. Thus, apologies are extended in advance to those whose work I have might have missed and to those unknown to me whose unpublished ideas may have seeped into the pool of common knowledge without appropriate recognition. The analysis here addresses events of two time segments, an older one extending from the developments at Bingham in the early 1900s through the Second World War, ending about 1950: the second period extends from that time to the present. This separation is seen in Figure 1, which traces numbers of publications through the period as extracted from some 700 publications, again with a North American bias, from an annotated bibliography of porphyry copper geology in preparation. During the early period, exploration was "immature" in North America, that is, geologists looked for new districts and sites of the deposits. Outcrops were sought that carried the signatures of former mineralization and regional controls related to structural geology were closely studied. In the later period, North American exploration had "matured" into a study of districts, rather than a search for them. As the studies of these ores intensified during the younger period concommitant with increasing demands for the metal, they did so with a broadened understanding of some habits of occurrence, of hydrothermal alteration, mineral zoning, petrology, and geochemical and geophysical signatures. Outside of North America, search remained "immature" but closely related to the

Jan 1, 1998

By E. Steel, V. S. Znamensky, A. Wylie

The asbestiform habit is most commonly developed in certain amphiboles and chrysotile, but other minerals also may crystallize with this unusual habit. The habit may be characterized by (1) a fibril structure, single or twinned crystals of very small widths (generally less than 0.5 pm), which have grown with a common fiber axis direction, but are disoriented in the other crystallographic directions; (2) anomalous optical properties, primarily parallel extinction; (3) unusual tensile strength; (4) high aspect ratio; and (51 flexibility. In addition, there is evidence to indicate that some amphibole asbestos may have unusual surface properties. ASBESTOS AND THE ASBESTIFORM HABIT Asbestos is defined as a group of highly fibrous silicate minerals that readily separate into long, thin, strong fibers of sufficient flexibility to be woven, are heat resistant and chemically inert, and possess a high electric insulation, and therefore are suitable for uses where in- combustible, nonconducting, or chemically resistant material is required (Gary, et al., 1974). The most common minerals that may occur with the asbestiform habit are chrysotile, grunerite (amosite], riebeckite (crocidolite), actinolite, anthophyllite, and tremolite; although the development of this habit among these minerals is rare. Other minerals, most notably other amphiboles, can occur in this habit, but no others have been mined commercially as asbestos. All asbestos is confined to metamorphic rocks, even though other habits of the amphiboles are common in igneous rocks. Slip fiber veins are the most common deposits (South African amosite, Canadian chrysotile, etc.), but mass fiber deposits also may occur such as California chrysotile or mountain leather. Field relations and experimental data support the hypothesis that metasomatism is the dominant process in the formation of asbestos fibers, amphibole as well as serpentine. The crystal habit of a mineral is the shape or form a crystal or aggregate of crystals take on during crystallization. The asbestiform habit has a number of characteristics that differentiate it from other habits. Chief among these is the fibril structure.Afibri1 is a single or twinned crystal with a very small width, generally less than 0.5 pm, and an extremely high aspect ratio; bundles of fibrils may have lengths reaching into the cm. Fibrils share a common crystal growth direction along the long axis of the fiber, but appear to be disoriented with respect to one another in the other crystallographic directions. The structure of the individual fibrils, and the organization of fibrils within a fiber may differ among the various types of asbestos. The fibril structure of asbestos is probably a factor in controlling a number of secondary properties that include high tensile strength, flexibility sufficient for weaving, and anomalous optical properties. The high tensile strength of asbestos is quite remarkable, exceeding that of the ordinary varieties by a thousand fold (Zoltai, 1978). In part, this may be attributed to the lack of defect on the fibril surfaces (Zoltai, 19781, but some contribution also must come from the existance of bundles and the nature of the ordering of and forces among the fibrils. The flexibility is not only enhanced by the fact that the fibrils may slip past one another, but by their small widths and extreme aspect ratios. However, structural defects parallel to the fiber axis also may contribute to this property. Among the common commercial asbestos types, the greatest flexibility is found in chrysotile and the least in grunerite asbestos (amosite), varying inversely with fibril thick- ness. In addition, at least for chrysotile, composition also may affect the flexibility of the fibers. Finally, most asbestos minerals are mono- clinic, but optically display parallel extinction (Heinrich, 1965, and Wylie, 1978). This also must be due, in part, to the ordering or lack of ordering of the fibrils. The fibril structure is probably a random

Jan 1, 1986

By Balesh W. Konda, Andrew B. Cecala, George W. Klinowski

Methane ignitions continue to be a major concern to the longwall mining industry. In spite of numerous advances in technology over the past decade, there has not been a measurable reduction in the number of longwall face ignitions. These ignitions will continue to be a problem as deeper and gassier seams are mined, as production rates are increased through numerous improvements in longwall mining equipment, and as the output of the workforce increases due to improved management-labor relations. It is necessary to know methane liberations, emissions, and flow patterns in order to effectively deal with it and to design control technology to reduce the occurrence of longwall face ignitions. A cooperative research project between the Bureau of Mines and the Canada Centre for Mineral and Energy Technology (CANMET) has been established to address longwall methane problems. The initial direction of this work was to look at methane flow patterns during the entire longwall mining process, and more specifically to examine and compare methane levels and flow patterns for advance and retreat methods of longwall mining. Both advance and retreat longwall mining is practiced in the Sydney coal fields in Nova Scotia. In 1986, a study was performed on advancing longwall panels at the Lingan Colliery, and a similar study was recently completed at the Phalen Colliery on a retreating panel. Methane monitors were placed at various locations along the face, intake, return, and bleeder airways. Handheld methane monitors were also used upstream and downstream of the shearer mining machine. This setup allowed a determination of methane sources on the longwall panels, including: liberation from cutting with the shearer mining machine, emissions from the coal seam along the face, emissions from the gob area, and methane already in the intake air. The results from both studies are reported and the differences between the two longwall mining methods compared.

Jan 1, 1989

By Frank R. (Original by) Barnako

Coal mining historically has been a hazardous occupation but, in recent years, tremendous progress has been made in reducing accidental coal mine deaths and injuries. The purpose of this chapter is to discuss the basic principles of accident prevention as they are related to coal mining. Accident prevention fundamentals are no different for coal mining than for any other type of work. The fundamentals apply to all industries. Construction workers may be struck by falling tools and materials, and miners may be struck by falling slate and coal. Sailors may be trapped by shipboard fires, and miners may be trapped by mine fires. Railroad brakemen may lose hands and fingers positioning couplers, and miners may lose hands and fingers positioning couplers. Many other examples could be cited, but the point is that accidents that happen in coal mines are basically similar to accidents that happen in other industries. Thus, the basic principles for preventing accidents apply in coal mining as they do in any other type of work.

Jan 1, 1981

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 Kenneth N. Han, Yichang Guan

The dissolution behavior of metals from Au/Ag/Cu-alloys has been studied using rotating disc electrodes in solutions containing acids, cyanide, and ammonia. Electrochemical methods as well as leaching tests were adopted in this study. The results showed that there was no galvanic effect on the dissolution of metals from homogeneous alloys. In aerated cyanide solutions, the dissolution of gold, silver, and copper from their alloys was partly controlled by surface chemical reaction, but largely by mass transfer. On the other hand, the galvanic coupling effect played a very important role in heterogeneous alloy systems.

Jan 1, 1995

By E. J. Miller

The Ventilation Branch is engaged in a project to determine if low level carbon monoxide monitors used for early detection and warning of fire in a coal mine conveyor belt entry can provide protection equivalent to that of thermally actuated point type heat sensors commonly used for fire detection. A series of tests were conducted to determine the required operating parameters, such as sensor spacing and alarm levels of detected carbon monoxide to provide equivalency between' these methods of fire detection. This report summarizes the results of these tests.

Jan 1, 1980