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By P. D. Rao

Although phosphorus is a very important biogenic element, its concentration in coal is generally low. Phosphorus concentrations typically range from 0.001 % to 0.229% in raw coals of the contiguous 48 states. Some Alaskan coals in the Cook Inlet region contain horizons unusually high in phosphorus. A foot by foot analysis of deep drill core, containing 70 ft. of sub bituminous 'C' coal from the Beluga coal field, Alaska, showed certain increments contained as high as 17.03% P2O5 in the coal ash; 1.01 % P on a moisture-free coal basis. Crandallite has been identified by electron microprobe analyses as a phosphorus numeral in these coals. The authors could quantify calcium, barium, strontium and phosphorus concentrations from the coal attributable to crandallite. These high phosphorus coals provided a unique opportunity to study the association of phosphorus in coals using chemical fractionation for exchangeable cations and acid extractable elements. Since the source of high phosphorous horizons in Cook Inlet coals is attributed to volcanic ash, it is suggested that the profiles of acid extractable phosphorous concentration may be useful for coal seam correlations.

Jan 1, 1992

By David Green

Outokumpu introduced Flash Flotation in the early l 980's for the recovery of floatable material from grinding circuits. The devel­opment came as a result of surveys made in the company's own concentrators, initiated to find ways of improving recoveries with increasingly complex and lower grade feeds. Hydrocyclones make a separation on the basis of particle size and mass, resulting in the "over collection" of fine grained, high S.G. particles. Minerals such as pentlandite, galena and gold are easily caught in the circulating load around the mill until they are overground and rendered more difficult to collect. In the case of downstream flotation this may simply involve a reduction in the rate coefficient due to the finer sizes or, as is commonly experienced in gold operations, the mate­rial is slimed and coated onto non-floating gangue and is eventual­ly lost to tails. At the time of Outokumpu's plant surveys, it was a relatively common practice, particularly in Pb operations, to have a flotation section fed directly from the secondaiy mill discharge. This is called unit flotation and certainly provided an improvement but very high wear rates and frequent sanding out of the cells was com­mon. The development of the SkimAir® Flash Flotation cell by Outokumpu provided a subtle but quite dramatic departure from the unit cell approach. Now it was possible to feed cyclone under­flow into a special purpose-built flotation machine and recover a final grade concentrate from the grinding circuit (see Figure I). The cell was designed to handle the coarse circulating load, per­mitting the coarsest fractions to be short-circuited back to the mill and retain the floatable sizes for a nominal time of 30 seconds to several minutes. The short retention time was possible largely due to the relatively clean content of the cyclone underflow stream. This means that the fine gangue is not present except in small quan­tities and most of the fine to mid-size paiiicles are higher S.G. and more likely represent valuable mineral. This condition provides for very high rate coefficients. Typical operations would recover 40-60% of the valuable mineral in this fashion and improvements in recovery were typically from 2-5% for sulphide minerals to the 5-20% range for gold and silver.

Jan 1, 1998

By James E. Lawver

Part I describes the general geology of the Florida deposits. As the lucrative Bone Valley Formation is depleted, replacement production will move progressively into areas of total Hawthorn production. The reserves of the immediate future are a mixture of two distinct ore types referred to as the upper (high grade) zone and the lower (low grade) zone. The upper zone is somewhat similar to the Bone Valley Formation that has been Florida's source of production for the past 100 years and will respond favorably to present beneficiation practices. By contrast, the lower zone ore contains significant quantities of dolomite that must be removed in order to produce an acceptable grade pebble or flotation sized product. Part II reviews past practice and describes future trends in mining and ore transportation. This presentation (Part III) is confined to the problems of beneficiation, waste disposal, and environmental regulation.

Jan 1, 1983

By A. Mahtab, S. Xu, P. Grasso, B. J. Fu

The large population base, complex geology of the large land mass, and notable commercial activity have accelerated the development of underground construction market in China. The projected lengths of underground openings per year in the various sectors are: hydro-tunnels, 180 km; coal mine entries, 40 km; transport-tunnels, 300+ km. An example of the mega projects (being planned by the Government) is the water supply scheme for connecting Yangtze river to Yellow river involving 131 km of water tunnels with a diameter of 8-10m. Several large projects are highlighted in the paper with reference to the schemes for generating hydro-power, mining of coal and minerals, and constructing transportation networks. The related problems of construction and geomechanics are outlined.

Jan 1, 1995

By R. J. Pindred

Discussion by R.J. Pindred In his paper, Davis presents an overview of risk. He also introduces the Capital Asset Processing Model (CAPM) as a foundation for selecting the appropriate discount rate for a mining project. While applying portfolio theory is more defensible than the ad hoc adjustment of discount rates, the CAPM is not a panacea. CAPM shortcomings [The CAPM, as Davis stated, is expressed in the equation: ri=rf+pi4) where ri is the project discount rate rf is the risk free interest rate (3i is the project beta, and 0 is the market risk premium (rm - rf)] Application of the CAPM is more difficult than Davis indicates. Valuation is prospective, while the CAPM parameters are historical. Beta is determined from a regression analysis of historical data, while the beta needed for valuation is the expected beta. Betas are known to be unstable and the regressions that generate them often have low explanatory power. The difficulty of estimating a "project" beta must also be considered. Thus, the beta that is used in the CAPM will be based on the analyst's judgment. Like Cavender's discount rate, this judgment can lead to different project NPVs. Subjectivity in valuation cannot be avoided by a mechanical application of the CAPM. The risk-free rate, which Davis identifies as a short-term real rate of 4%, is also subject to scrutiny. A mining project is not a short-term investment and no single risk-free rate is appropriate for all of the cash flows. The hypothetical mine discussed in Cavender's paper is a six-year project. One might argue for the application of a risk-free rate from the Treasury yield curve at the duration of the project (in a bond-duration sense). This, too, is inappropriate. The risk-free rate should be matched to the timing of the cash flow. These rates can be determined by calculating the implied forward rates from the yield curve using a procedure known as "bootstrapping." It is likely that each of the project's cash flows would be discounted at a different rate. Commodity prices Davis criticizes the "ad hoc adjustment to the discount rate." Yet, in his discussion of the value of stochastic simulation, he suggests that the gold price be modeled as a "random walk, with or without a trend." This is essentially an arbitrary modeling of price risk. Consider that a liquid market in gold futures exists. The futures' price curve, which is closely related to the market's estimate of future spot gold prices, should be used to provide inputs to the model. This is especially true of a relatively short six-year project. Alternatively, as Davis correctly points out, a risk-averse investor can sell the commodity short to hedge price risk. Is it any more correct, in the portfolio sense, to account for price risk at all ?? References Cavender, B., 1992, "Determination of the optimum lifetime of a mining project using discounted cash flow and option pricing techniques," Mining Engineering, Vol. 44, No. 10, pp.1262-1268 Fabozzi, F.J., 1993, Bond Markets, Analysis and Strategies, Second Edition, Prentice Hall, Inc. Higgins, R.C., 1992, Analysis for Financial Management, Third Edition, Richard D. Irwin, Inc. Solnik, B., 1991, International Investments, Second Edition, Addison Wesley Reply by G.A. Davis Pindred discusses two issues related to my paper, the shortcomings of the Capital Asset Pricing Model (CAPM) and which commodity price values to use in the valuation exercise. Even though these topics are not directly related to the use or misuse of Monte Carlo simulation, they are important points to take into consideration in valuation exercises. Since I do not appear to have addressed these issues satisfactorily in my original paper, I will comment on each here. Pindred agrees with me that applying portfolio theory, and specifically the CAPM, to the selection of project discount rates is more defensible than ad hoc methods. But he then points out that the application of the CAPM to project valuation is more difficult that I indicate. It is true that the CAPM is a difficult tool for project valuation in general,. But the application of the CAPM to mining projects is one of the easiest I can think of. The biggest problem with using the CAPM for project valuation is coming up with an expected project beta. I suggest a project beta for gold projects of 0.45. The "true" value might be 0.35, 0.55 or whatever. Pindred correctly notes that the selection of the appropriate project beta is based

Jan 1, 1996

By B. DANIEL MARJAVAARA, I. A. SOFIA LARSSON, ANNA-LENA LJUNG

One way to upgrade iron ore is to process it into pellets. The pelletizing process is multifaceted, involving complex fluid dynamics with highly turbulent, high-temperature flow in intricate geometries. This makes it hard to perform measurements during operation, so a useful tool for better process understanding is computational fluid dynamics (CFD), where the challenge is to perform efficient and trustful simulations of complicated problems. A validated simulation model can be valuable for increased process control and development. In this paper, the flow field and coal combustion process in a pilot-scale iron-ore pelletizing kiln is simulated using a CFD model. The objective of this work is to apply a coal combustion model to enable an investigation of thermal effects from the flame on the surrounding flow field.

By Chen-Luh Lin, Jan D. Miller, Sindhoora Puvvada

Most of the future phosphate resources in Florida, which accounts for 70  percent of production in the United States, are contaminated with too much dolomite that is difficult to remove with existing industrial practices. The low-grade ore quality coupled with increased phosphate demand is of concern to the Florida phosphate industry. In order to resolve the dolomite issue, various beneficiation technologies were designed and evaluated, but none have been sufficiently successful [1]. 

By Robert Kimutis, Lihong Zhou, Mark Mazzella, Jim Addis

Due to the surge in shale gas production, a substantial number of unconventional shale gas wells have been drilled across U.S. coal reserves. Gas breaches resulting from damaged wells pose a considerable safety risk to miners. This paper investigates how a ventilation system can effectively manage breached gas through a network-based numerical model and laboratory-scaled physical model. Several hypothetical gas breach scenarios in a longwall area are simulated, exploring factors influencing gas mitigation. The study establishes correlations between breached gas inflow and gas concentration at critical locations. The findings in this study provide valuable insights for managing mine ventilation systems and enhancing coal miner safety.

Feb 1, 2025

By Rudolph K. Hoagberg

Silica sands, primarily in coarse size ranges, are used to prop open fissures or voids created in the bedrock by hydraulic fracturing. This procedure increases the flow of gas or oil or other fluids through the bedrock. The sands used must meet various specifications relating to their physical and chemical characteristics; these characteristics are in turn related to the geologic provenance of the sand deposit. The Jordan Sandstone, a Cambrian formation which is exposed in Minnesota and Wisconsin, meets the specifications of a proppant sand by virtue of its depositional history and its sedimentary properties.

Jan 1, 1980

By J. Morris, R. Sellaro

El petrodiesel es un colector común para la flotación de carbón, pero la partición de compuestos orgánicos de diesel (DRO por sus siglas en inglés) en corrientes de proceso no ha sido ampliamente estudiada. Investigaciones preliminares sugieren que bajo esquemas de dosificación normales los contenidos residuales totales de DRO en aguas de procesos deben estar limitados a la fracción soluble en agua (WSF por sus siglas en inglés) sub-ppm. Es más, los hidrocarburos aromáticos poli-cíclicos (PAH por sus siglas en inglés) debería segmentarse de manera proporcional con los compuestos orgánicos de diesel (DRO). El propósito de este estudio fue confirmar estos resultados en pruebas de flotación realizadas en laboratorio. Se midieron los contenidos totales de DRO Y PAH en aguas asociadas con los flujos o corrientes de concentrados y relaves. Los resultados muestran que las aguas con concentrados tenían de manera consistente mayores cantidades de DRO que las aguas de relaves. Es más, los contenidos de DRO en ambos flujos generalmente se incrementaban con el aumento de la dosis de diesel. De acuerdo con la investigación preliminar, los DRO parecían estar limitados a la fracción soluble en agua (WSF) y los PAH tendían a segmentarse proporcionalmente con los DRO. Bajo condiciones de operación típicas, los DRO residuales no deberían representar una preocupación medioambiental, pero deben evitarse situaciones que permitan una sobredosis significativa de diesel.

Jan 1, 2014

By H. P. van Ormer

The objective of this paper and the developed personal computer program is not to identify or try to identify the actual total drilling cost in any Rotary Drilled Blast Bole Program. The ideas put forth here and in the computer program developed are a very accurate way to measure what is often very hard to identify and interpret -The actual direct operating cost of various drilling package combinations including comparing with available blast hole sizes and patterns

Jan 1, 1988

By J. Baz-Dresch

A custom-designed shotcrete system, consisting of an 8-m3 (10-yd3) transit mixer and a shotcrete spray boom carrier, is used bya 2-man crew to transport and place up to 25 m3 (32 yd3) of steel-fiber reinforced, dry, silica fume shotcrete per II-hour shift. Shotcrete is custom blended by a local supplier and delivered predampened. Mix design and quality control is performed with a computer program that develops and graphs a properly balanced mix based upon the materials sieve analyses.

Jan 1, 1991

By J. Paraszczak

Metal mining at great depths presents a number of serious challenges for mine operators. Among them is the high demand for fresh air required to cool down mine openings, evacuate noxious gases and contaminants and provide sufficient amounts of oxygen for miners. At the same time, modern mechanized mines extensively use diesel-powered load-haul-dump (LHD) machines, trucks and other mobile equipment. These vehicles not only emit exhaust gases and diesel particulate matter (DPM), but constitute an additional source of heat. As mine regulations get steadily more stringent with regard to air quality, the use of diesel engines has an additional adverse impact on ventilation costs. In this context, the present paper examines possible alternatives for diesel power trains, both those commercially available and those in development. They are reviewed with regard to their principles, required infrastructure, stage of technology development and progress. The questions of their flexibility, practicality and economic viability are also addressed. Finally, their possible benefits and potential for implementation in the conditions of deep metal mines are discussed. The paper concludes with short- to medium-term predictions concerning promising drive alternatives for vehicles destined to operate in deep metal mines.

Jan 1, 2009

By A. Davis

Pit lake chemistry depends on the lithology and hydrologic characteristics of the ultimate pit surface, the availability of buffering capacity in the wall rock versus oxidizable sulfide content, and the alkalinity of recharging ground water. In this paper, we assess the geochemistry of 11 existing pit lakes, ranging from the acidic Red Hill and Berkeley pit lakes (pH 2.6 to 2.8) to the alkaline Yerington Pit lake (pH 8.45). Predicted pit lake chemistry is similar to that in existing pits with the long-term pit lake chemistry lying on a geochemical continuum between end members consisting of influent calcium bicarbonate ground water, and naturally occurring sulfate-rich evaporite playa lakes.

Jan 1, 1996

By J. Noll, E. Cauda, T. Barone, S. Vanderslice

Measuring diesel particulate matter (DPM) for underground metal/nonmetal mine compliance samples is done by collecting DPM onto quartz fiber filters and analyzing the samples via NIOSH method 5040 for elemental carbon (EC) and total carbon (TC). As part of the sampling train, two quartz fiber filters in tandem are housed inside an SKC DPM cassette that includes an impactor. The impactor segregates DPM and mine dust, and the second filter is used to correct for adsorption of vapor phase organic carbon (OC). Since the value of the second filter is subtracted from the first, the pre-existing carbon on the filter media for both filters needs to be comparable. In addition, the pre-existing carbon on the media should be low for accurate and sensitive results. However, there have been some reports of elevated OC on the filter media of the SKC DPM cassettes, which would cause the limit of detection (LOD) to be higher than reported at times. In this study, blank SKC DPM cassettes from different batches and with different expiration dates were analyzed to quantify the amount of carbon on the filter media and to determine the LOD and limit of quantification (LOQ) associated with these samplers. It was found that the organic carbon and total carbon on the media was about five times higher than quartz media used in samplers from other studies. The average TC on the blanks was 2.57 μg/cm2 with a standard deviation of 0.70, resulting in a LOD of 21 μg/m3 TC, 8-hr Time Weighted Average (TWA), and LOQ of 69 μg/m3 TC, 8-hr TWA, when using these samplers for collecting DPM. The LOD and LOQ may be improved through some sample preparation techniques. INTRODUCTION Exposure to diesel exhaust (DE) is associated with an increased risk for lung cancer and other adverse health effects (Attfield et al. 2012, Silverman et al. 2012, Ping and Guang 2017, IARC 2012). Pronk et al. 2009 reported that the highest exposed groups to elemental carbon (EC) from DE worked in underground sites in mining and construction and they were exposed to concentrations between 27–658 μg/m3. At concentrations (1–25 μg/m3 EC) well below those observed in mining, diesel particulate matter (DPM) exposures were estimated to increase the risk of cancer by levels exceeding those typically acceptable for occupational risk in the United States and Europe (Vermeulen et al. 2014). This suggests that underground miners are especially at risk because of their more substantial exposures in confined working spaces. As a protective measure, in 2001, the Mine Safety and Health Administration (MSHA) promulgated a rule to limit exposures of metal/nonmetal underground miners to DPM to an 8-hr time-weighted average (TWA) of 160 μg/m3 total carbon (TC) (MSHA 2001, 2006).

Jan 1, 2019

By James R. Taylor

24.1-BASIC PRINCIPLES JAMES R. TAYLOR The basic principle involved in maintenance is protection of a company's investment through the care and upkeep of machinery and equipment, buildings and properties. Maintenance is justified through making available to the maximum extent possible the facilities, machines and services required by the operating and production departments in their function of insuring optimum return on investment. As the size, cost and complexity of the equipment used in modern mining and related industries increase, operating and production personnel become proportionately more dependent upon maintenance engineering for its contribution to the overall profit picture. A greater part of the total cost now is charged to maintenance and the maintenance group becomes a major company unit. Basic maintenance concepts have changed very little over the years, but the advances in methods and technique have brought about tremendous challenge and have in consequence assumed a greater influence and importance. The older "sledge- hammer" methods have given way to engineered and scientific systems, while the accelerating development of intricate equipment and machinery, and the instrumentation essential for control, demand an ever-increasing upgrading of maintenance personnel. Regardless of this growth in importance, cost and complexity of the maintenance function, it is important to remember that it is not an independent and self-sufficient unit, but is a necessary facet of the entire plant operation and is subject to the company's total production effort. As one part of a team, maintenance is successful only when functioning cooperatively wit11 the other departments it serves Close collaboration in all areas served by n maintenance group is essential if it is to function fully to protect the company's investment, whether the assets are in machinery, materials or people. 24.1.1-MAINTENANCE SCOPE Maintenance functions may be grouped into the two general classifications of primary and secondary. This grouping constitutes a basic division although, in practice, the scope of the maintenance activity varies in each mine or plant and is subject to differences in size and type of operations and company policy, plus the influence of precedent, which may be sectional or industry-wide. The primary functions supply the justification for the maintenance engineering department. while secondary functions are variable according to plant conditions and needs. The primary functions may be categorized as follows: 1. Maintenance of existing machinery and equipment. 2. Maintenance of existing buildings and grounds. 3. Inspection and lubrication of equipment and machinery. 4. Utilities generation and distribution. 5. Alterations to existing equipment and facilities. 6. Installation of new equipment and facilities. 7. Instrumentation.

Jan 1, 1973

By Errol L. Montgomery

The region of metalic ore deposits in northern Chile, southern Peru, western Bolivia, and northwestern Argentina occurs in arid zones at altitudes as high as 4,600 meters. Because surface water supplies are meager, new mines require unexploited sources of water. Prolific groundwater aquifers occur in salar basins in this region of the Andean Highlands. Exploration water wells have been constructed and aquifer characteristics have been tested in eight salar basins. Results indicate groundwater quality is good. Aquifer transmissivity and storage computed from results of pumping tests indicate maximum production water well capacities in excess of 170 liters per second.

Jan 1, 1982

By S. J. Ristorcelli

Historically, geologic data has not been adequately considered in resource estimation. More recently, with the use of computers and sophisticated estimation algorithms and geostatistical justifications, geology has been downplayed further. Many reasons are given for not using geology including cost, time and irrelevance. None are valid. Boundaries defining mineral domains should be used in computer-generated resource estimates. Selected case histories show how the failure to honor geology has caused discrepancies in resource estimates of actual in-place resources. After-the-fact differences have included decreases in tonnage of up to 50% and increases up to 300%; partial to complete recategorization of material; and 50% decreases in grade. The costs of gathering and using geology are trivial compared to the potential consequences.

Jan 1, 1994

By Larissa Koroznikova, Steve Durkin, Bradley Drake, Michael Tuck

This paper presents the results from the investigation of the application of thermal fragmentation in Australian hard rock underground narrow-vein mining. Two geologically similar samples from an underground narrow-vein hard rock gold mine were collected to obtain a measure of the technology’s ability to recover ore by the creation of large thermal openings to assess the applicability of the thermal method. Particle size distribution showed a higher generation of fine product, − 2 mm, by thermal fragmentation compared with selective blasting by 31%. The Bond work index for thermal ore (12.62 kWh/t) is half to that of the blasted ore value (25.32 kWh/t). The average grindability obtained for the thermal ore sample was greater than the blasted sample by a factor of 2.44, a higher value indicating a decrease in the energy required to grind. The thermal fragmentation method generates product with higher dissolution of gold in cyanide, by 14% for the − 9.5 + 2 mm size fraction samples. Additionally, the thermal fragmentation results in higher production of − 9.5 + 2 mm material by 15 % compared with selective blasting.

By B. D. Hansen

Newmont has been on a focused path of improving operations for many years. After the merger of Newmont and Santa Fe Pacific Gold, Newmont created significant synergies of over $50million per year in Nevada, primarily through optimal ore movements and consolidation of various functions. During the current period of low gold and copper prices, Newmont has refocused its efforts on efficient operations worldwide. This paper will describe the methods and programs that continue to be implemented at Newmont's many mine facilities in Nevada. Newmont has used a combination of computer technology, optimal use of infrastructures, procurement strategies, functional consolidation, enhanced mine planning and a variety of available metallurgical processing options to decrease the cost of operations and increase profitability.

Jan 1, 1999