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By Wayne W. Murdy

Since 1993, Newmont Mining has been growing through the development 'q of three major foreign mining operations with a fourth under construction. The first project, Yanacocha in Peru, began operating in October 1993. This occurred at a time when political and business risk in that country was considered high. In 1995, Newmont began operating the Muruntau joint venture in Uzbekistan. It is the first mining project of its kind in the Confederation of Independent States (CIS). In early 1996, Newmont started operating the Minahasa Mine in Indonesia. In early 1997, Newmont began construction of a $1.9-billion project in Indonesia. The company is also completing a feasibility study with its partner for the development of a gold operation in Mexico. All of these projects have been considered "risky" by most standards. Newmont has been successful in all of them through risk mitigation programs. These programs include using strong and successful in-country partners, concentrating on developing a strong national workforce with minimal expatriate employees, using World Bank, European Bank for Reconstruction and Development (EBRD) and International Finance Corp. (IFC) financing and building and maintaining strong ties with host governments.

Jan 1, 1997

By D. Robert Weir

The pioneers in pressure hydrometallurgy have provided a solid foundation during the past four decades. The pressure techniques are now capable of being used to push back the frontiers in the winning of metals. Pressure hydrometallurgy has been used to meet the objectives of extracting metals; purifying metal solutions, recovering metals; and rendering waste streams acceptable for disposal to waste repositories and the environment. Some examples of each of these functions are briefly reviewed. The applicability of pressure techniques to the recovery of precious metals is discussed.

Jan 1, 1985

By P. James, L. J. Steiner, F. Turin

NIOSH researchers and an industry partner conducted an investigation to study the effectiveness of ergonomic interventions in mining. The study required a significant commitment of time and resources from the cooperating site, Bridger Coal Company. This paper focuses on some of the challenges faced by the researchers and their cooperator. Challenges included the need to redesign methods of identifying and prioritizing injuries, and the need to train the workforce in ergonomics while still maintaining progress and interest in the process. The authors discuss some practical interventions implemented by Bridger Coal to date, and discuss future research implications brought about by PacifiCorp’s Generation Business Unit, who monitored the project to determine whether an employee-owned ergonomic process could be implemented throughout their operations.

Jan 1, 2003

By Laurence M. Demers, Douglas C. Kuhn

It has been suggested that radicals on the surface of dust particles are key chemical factors in the pathophysiology which results from the occupational inhalation of coal and silica dust. In addition, oxygenated derivatives of arachidonic acid (eicosanoids) have been implicated as important biochemical mediators of mineral dust-induced lung disease through their role in bronchial and vascular smooth muscle reactivity, inflammation, and fibrosis. Therefore, we assessed eicosanoid production by the rat alveolar macrophage (AM) exposed in vitro to mineral dusts with varying surface chemical characteristics in order to determine if radicals associated with the mineral dub1 could influence the production of pro-inflammatory mediators in the lung environment. Rat AM were exposed to freshly fractured or "stale" bituminous coal dust, as well as untreated silica or silica calcined to 500°C and 1100°C. Prostaglandin E2 (PGE2) and thromboxane B2 (TxB2) levels in incubation medium were determined by specific radioimmunoassay. When AM were exposed to freshly fractured coal dust, PGE2 and TxB2 production were markedly increased. In contrast, exposure of AM to "stale" dust significantly reduced PGE2 and TxB2 production. In vitro exposure of AM to untreated silica resulted in a significant increase in PGE2 and TxB2 production compared to control. However, exposure of AM to silica calcined to 1100°C resulted in eicosanoid levels which were not significantly different from control. These findings suggest that radicals associated with respirable coal and silica particles may play a key role in the ability of mineral dust to activate AM eicosanoid production.

Jan 1, 1991

By Al. Valero

This paper quantifies in universal units (energy units), the annual decrease in the mineral endowment of the planet. This is done for some important extracted non-fuel minerals, namely aluminium, cobalt, chromium, copper, gold, lead, uranium and zinc and is compared with the depletion figures of conventional fossil fuels. The results of this study reveal that each year, the decrease of the global non-fuel mineral bonus provided by Nature is 2 to 3 orders of magnitude greater than the loss associated to the burning of fossil fuels. Particularly for 2008, the depletion in mineral wealth of the studied commodities was about 20 times greater than that of fossil fuels. The assessment methodology is based on the Second Law of Thermodynamics. It quantifies the useful energy (exergy) required to concentrate a mineral from a completely dispersed state in the crust, to the conditions of composition and concentration found in the mines. Exergy can be a useful measure for quantifying the mineral depletion caused by man, as it takes into account the main physical features that make minerals valuable: composition and concentration. This analysis enhances and puts numbers to the importance and necessity of material reuse and recycling.

Jan 1, 2011

By M. A. Pipke, C. M. Brown

The semiautogemus grinding circuit at the Utah Mines Ltd., Island Copper operation, located on Vancouver Island, British Columbia, is described. Since startup of the operation in 1971, grinding circuit throughput has been progressively increased from the initial design rate of 90 000 (99,000) to the current average 45 000 t/d (49,600 stpd) of porphyry copper ore. Key developments ad modifications in operating and maintenance practice that have contributed to this increase are reviewed.

Jan 1, 1987

By G. Pan

A geostatistical approach is proposed for the design of infill drilling programs. The method consists of the following four major steps: developing geological favorability models, delineating mineralization and ore envelopes, classifying resource potentials, and designing infill drilling patterns. Geological modeling develops the permissible geological zones in which infill drilling is designed. Modeling mineralization and ore envelopes establishes criteria on the potential blocks to be drilled. The blocks that are included within the ore envelopes are considered in the infill drilling. The following four types of resource potentials are used in this analysis: measured, indicated, possible and barren. Blocks in the indicated category are the top targets to be confirmed in infill drilling. Blocks of possible resources may be considered exploration targets. The algorithms involved in the analysis include indicator favorability analysis, indicator kriging and ordinary kriging. A case study on a gold deposit of the Carlin type is presented to demonstrate the methodology. The deposit was originally delineated by a sparse drilling program with about 230ft of average spacing. The infill drilling design, based on the new method, suggests a significant reduction on the number of holes from a regular-grid infill drilling pattern.

Jan 1, 1996

By M. Menegaki

Restoration of abandoned mine sites is still one of the weak points of mining practice. The latter stands especially for the case of the surface coal and lignite exploitations, where the extended size of the disturbed land and the drastic changes to the geomorphologic features do not facilitate the implementation of a cost effective and environmentally sound reclamation plan. The paper examines the parameters involved towards the legal requirements for the reclamation of the first lignite exploitation in Greece, namely the ?Plakes? mine, located at Euboea, due to the particularities of the site. Then an integrated redesign procedure is presented, aiming at minimizing aesthetic degradation, confronting technical difficulties and preparing the site to accept new uses.

Jan 1, 2005

By P. A. Tuzinski, L. J. Dahl, N. R. Adamson, S. E. Brink, R. L. Blake

The US Department of the Interior, Bureau of Mines is developing a process to selectively extract manganese from oxide ores as part of its in situ mining research program. The Bureau is conducting site characterization studies of two manganiferous iron-formation deposits. These studies include: drill core, regional stratigraphic relationships from the existing geologic database, ore body geometry, geologic structure, hydrologic conditions, accessibility of ore minerals to leach fluid, surface subsidence potential and data collected from laboratory leaching experiments. This information is being used to evaluate the technical, environmental and economic feasibility of in situ mining of manganese for these two deposits. This paper will focus on the stratigraphy, mineralogy, ore textures, fractures, permeability and porosity as they relate to in situ mining.

Jan 1, 1994

By J. J. Daniels

Advances in borehole geophysical research for mineral assaying and remote detection of mineralization away from the borehole are cited. Nuclear activation measurement research has provided accurate in situ assays of economic metals with neutron-gamma activation, using a high resolution intrinsic-germanium detector. Although nuclear activation analysis is the present "best hope" for obtaining in situ assays for some elements, gamma-gamma and magnetic susceptibility measurements can provide accurate assays for lead-zinc and magnetite, respectively. Borehole optical spectroscopy and X-ray fluorescence are being investigated as possible in situ assaying techniques for some minerals. More laboratory and field calibration research is needed before non-linear complex resistivity (NLCR) can be routinely used as a quantitative assaying tool. Field tests have shown that variations in the local geologic environment can affect the quantitative accuracy of assay values from downhole NLCR measurements. Deeply penetrating borehole geophysical methods are increasingly being used for mineral exploration as drilling costs and exploration have increased. Borehole electrical measurements have been shown to be useful for detecting conductive ore bodies that are not intersected by a drill hole. Hole-to-surface resistivity and surface-to-hole time-domain electromagnetics are demonstrated to be particularly effective for defining mineralized zones in a massive sulfide environment. Borehole gravity meters and three-component magnetometers have been developed and should prove useful for defining geologic anomalies away from the drill hole.

Jan 1, 1987

The 70th Annual Meeting of the Minnesota Section of SME and the 58th Annual University of Minnesota Mining Symposium were held April 22-24, 1997, in Duluth, MN. About 450 attended both. The Fifth Annual Trade Expo, held during the meeting, was attended by a record 80 exhibitors. An SME short course on materials handling preceded the meeting. Iron-mining and the steel industries highlighted the meetings. Specific topics in the keynote addresses and technical sessions primarily concerned iron mining, iron- ore processing, product (taconite pellet) transportation and the steel market. Although the iron mining industry held center stage, several papers outside of iron mining were also presented. Iron mining in Minnesota contributes $1 billion to Minnesota's economy. According to the Iron Mining Association of Minnesota, more than 20,000 state jobs rely on the industry. Minnesota's iron mining industry came through tough times in the early 1980s, mostly because of worldwide competition. However, the industry has shown significant improvement in the last 15 years. A large share of the steel industry's competitiveness in the late 1990s is due to cost and quality improvements in the taconite mines. The taconite industry has become more productive, largely through the application of new technology. Since the early 1980s, Minnesota's taconite mines have nearly doubled the number of tons per worker-hour. Most of the taconite reserves in the United States are located in Minnesota's Mesabi, Vermilion and Cuyuna iron ranges. The Mesabi range alone contains an estimated 24. Gt (23.6 billion long tons) of mag- netic taconite. Since the 1950s, when taconite production first began, 1 Gt

Jan 1, 1997

By Susan T. Bagley, Linda D. Gratz, Kirby J. Baumgard

The extensive use of heavy-duty diesel engines in underground mines has raised concerns about the potential adverse health effects to miners exposed to diesel particulate matter (DPM) which contains mutagenic and carcinogenic organic compounds. The purpose of this study was to compare the levels of DPM, biological activity, and polynuclear aromatic hydrocarbons (PAH) attributable to diesel engines in underground coal mines and similar data collected in engine laboratory facilities to assess whether laboratory data could be used to predict in-mine levels of diesel emissions. Mean in-mine DPM and SOF concentrations varied from 0.90 to 1.9 mg/m3 and 0.08 to 0.40 mg/m3, respectively. DPM-associated mutagenicity (mean) levels at two of the mines varied from 400 to 970 revertants/m3. Concentations of three PAH differed by up to four-fold between two of the mines, largely reflecting differences in DPM and SOF levels. The laboratory raw exhaust data were divided by 100 to obtain expected or predicted values for in-mine concentrations. The predicted DPM, SOF, mutagenicity, and PAH values based on laboratory samples were not significantly different from many of the in-mine values. Using a potential in-mine dilution ratio range of 20 to 200:1, virtually all in-mine data fell within the predicted range. Therefore, an estimate of in-mine concentrations can be determined by evaluating laboratory data. This will allow for extrapolations from laboratory tests with particulate emission control devices to assess potential health-related benefits due to their in-mine use.

Jan 1, 1991

By G. Yang, M. J. McPherson, P. Mousset-Jones, G. Danko, F. Calizaya

In the last 20 years, studies on controlled flow recirculation in various countries have been carried out in both coal and metal mines. These studies have shown that in addition to economic gains, partial flow recirculation can be used to provide mine workings distant from surface access points with the required volumes of air. These studies have also shown that the operation of fans and regulators, used in a recirculation system, will induce transients in gas flow and gas concentration. Various models have been developed to explain the problem. However, most have failed to incorporate important factors such as diffusion and dispersion in the modeling process. This study examines the theoretical background of gas emission transients from caved areas in coal mines, represents the problem by a "tank-airway" network model, and provides a possible solution. The study also presents the results gained from a laboratory model constructed to evaluate the major factors affecting the shape and duration of gas flow and gas concentration transients in an airflow recirculation system. In this model, the gas injection system was rearranged to simulate the variations in gas emission rates due to changes in air pressure. Within this model, a set of booster fans and regulators were used to generate the changes in air pressure within the model. Finally, the study presents an algorithm and a computer program GASTRAN, developed to analyze the gas concentration transients and calculate the pollutant transport levels in a complex ventilation network. The application of the program is illustrated by means of an example problem.

Jan 1, 1991

By David F. Gibson

This paper presents an outline of several models that have been developed to aid surface mine planners evaluate alternative mining methods and dragline sizes. The models presented belong to a larger group of models that are incorporated in the SEAMPLAN computerized mine and reclamation planning system. SEAMPLAN was developed in the College of Engineering at Montana State University. Initial funding for the development was derived from the USDA Forest Ser- vice and EPA. Enhancements to SEAMPLAN are currently being funded by DOE (Contract DE-AC22-80ET-14173). SEAMPLAN is a comprehensive surface mine and reclamation planning tool that contains a number of major modules: Data Entry and Review, Production Analysis, Reclamation Analysis, and Impact Analysis. The Production Analysis Module contains programs that enable the user to evaluate alternative methods of removing overburden in a surface coal mine and then to assess auxiliary activities required to support the overburden removal operation. A set of these programs addresses the use of draglines for removing overburden. Six basic dragline mining techniques have been modeled. For one-pass dragline operations four methods can be analyzed: (i) simple side cast, (ii) side bench, (iii) extended bench, and (iv) extended bench with side bench. Two methods of two-pass operations are modeled: (i) single dragline, and (ii) tandem draglines.

Jan 1, 1982

Load transfer capacity and failure mechanism of a fully grouted bolt installed across joints in shear is evaluated both experimentally and numerically in five types of bolts (low strength steel, rebar bolt and high strength steel). The strength of the concrete, bolt profile configuration, bolt mechanical properties and bolt pretension load play significant influence on the shear resistance, shear displacement and failure mechanism of the reinforced medium. Failure location moves towards the bolt joint intersection due to the increasing shear load, shear displacement and axial load developed along the bolt. Finally bolt failure occurs as a result of the induced axial and shear stresses acting between hinge points on either sides of the shear joint plane.

Jan 1, 2006

By Edwin H. Bentzen, Immo H. Redeker

Important industrial minerals are separated and concentrated by froth flotation by industry today. The following descriptions are presented as an overview of the methods employed to separate and recover a few of these industrial minerals. The minerals described in this section of the book are not, by any means, the only important minerals treated by froth flotation. Other minerals, such as calcite, kaolin, wollastonite, rare earths and vermiculite were not included, primarily due to the confidential nature of the information held by the Minerals Research Laboratory and the Colorado School of Mines Research Institute. Flotation of nonmetallic minerals is sometimes viewed as alchemy. However, the art is, in reality, based on sound chemistry, experience and a little luck in the treatment of new ores. In the flotation of nonmetallic minerals, as opposed to base metal sulfides, highly specific treatment conditions are required to accomplish separations. The presentation of the treatment of each of the minerals described was outlined as follows: DEPOSITS PROCESSING SPECIFICATIONS FLOWSHEETS (in some cases) A presentation of the factors, often critical, which must be carefully investigated to accomplish successful flotation of nonmetallic minerals is presented in the section on Sulfonate Collectors, elsewhere in this volume.

Jan 1, 1986

Cost reduction programs can focus on total cost or unit cost, but unit cost is usually the principal objective. The production cost per unit is: [Unit cost = Total cost Production volume] Consequently, any activity that reduces the total cost or increases the production volume will reduce the unit cost. Production volume is increased by (1) maximizing the availability of the production equipment and (2) maximizing equipment performance during periods of operation. Most operations managers routinely focus on volume because the factors influencing volume are generally well understood and congruent with the managers' technical skills. In fact, production volume (as a percentage of maximum achievable capacity) is widely recognized as one of the most significant measures of operational performance.

Jan 1, 1999

By N. Kuyucak

Acid rock drainage (ARD) resulting from the natural oxidation of sulfide mineral wastes has become a major concern to the mining industry, both during the operational period and after mine closure. ARD is generally characterized by high acidity and high concentrations of dissolved metals and sulfates. If the generation of acid cannot be prevented or controlled, it must be treated to eliminate acidity and to reduce the concentration of heavy metals and suspended solids before release to the environment. Microorganisms play an important catalytic role in the generation of ARD. Several prevention, control and treatment technologies that are based on microbiological activities have been developed. The role of microorganisms and biotechnology in the generation of ARD and their role in the methods used for prevention, control and treatment are discussed in this paper. Recently developed passive and biological treatment processes that have been implemented at mine sites are emphasized in this paper. Benefits, limitations and design criteria for passive biological processes are also presented.

Jan 1, 2000

By John E. Butler

Due to the present economic climate, particularly the depressed copper market, conventional mining, milling and flotation operations have been suspended. However, due to the apparent amenability of the ore to 'natural' leaching, investigations have been initiated into establishing an in-situ leaching operation as a preferred alternative to conventional operations. Cement copper production has been developed in parallel with the leaching trials and is presently at the rate of approximately 3,000 tonnes of contained copper per annum. Testwork includes controlled leaching of ore both in the laboratory and in-situ following blasting.

Jan 1, 1981

By J. L. Fuller

Thousands of mine air samples are taken underground each year by MSHA inspection personnel in order to further assure that miners have a safe and healthy environment in which to work. While most air samples are taken with stain tubes, many samples are obtained in evacuated containers and returned to a laboratory for more accurate analysis on a gas chromatograph. In order to enhance the accuracy, reliability and repeatability of the samples taken with evacuated containers, improved procedures have been developed, which are described in this report, for filling two different types of evacuated sample containers using either mechanical or electrical pumps. In those instances, such as when sampling strata gases in drill holes, where mathematical calculations may be required for proper sampling, example calculations are provided. The use of a third type of evacuated container, which is generally restricted to non-specific sampling of the ambient mine atmosphere, is also described.

Jan 1, 1986