Search Documents

By B. K. Cantrell

A miner working in an underground coal mine with diesel equipment is exposed to a wide array of pollutants from the diesel exhaust. These include CO, CO2, NO, NO2, SO2, diesel-exhaust aerosol, and a variety of hydrocarbon compounds. A quantitative definition of the health risk resulting from these exposures remains elusive, but during the past several years, progress has been made in defining the problem. Results from epidemiological studies by Garshick, et al. (1988); animal inhalation studies by Mauderly, et al. (1986); Iwai, et al. (1986); and Brightwell, et al. (1986); and in vitro studies by Lewtas, et al. (1986), have provided sufficient data for the National Institute of Occupational Safety and Health (NIOSH) to recommend that "whole diesel exhaust be regarded as a 'potential occupational carcinogen,' as defined in the Cancer Policy of the Occupational Safety and Health Administration," NIOSH (1988). NIOSH further stated that "though the excess risk of cancer in diesel-exhaust-exposed workers has not been quantitatively estimated, it is logical to assume that reduction in exposure to diesel exhaust in the workplace would reduce the excess risk."

Jan 1, 1990

By Donald Crowell

Due to falling metal prices and depletion of ore reserves, lead-zinc mining in the Leadville, Colorado, area gradually came to a halt in the 1950's. Exploration work continued, however, and by 1969 sufficient ore had been blocked out to warrant sinking a shaft and erecting a new concentrator to treat 700 tpd. The new shaft and concentrator were to be located in Iowa Gulch several miles east of Leadville at an elevation of 11,100 ft. The Leadville project is a joint venture between Newmont Mining Company and ASARCO with ASARCO being the operator. Design work began in the fall of 1969. Engineering was done by Torkelson Engineering Company of Salt Lake City in conjunction with the Central Engineering Department of ASARCO. The plant was constructed by Stearns-Roger Corporation. Construction began in the spring of 1970 and the plant went onstream in April, 1971. Flow sheets and equipment lists are attached. This paper will describe the flow sheet very briefly and discuss in more detail those aspects of the design which may be of interest, particularly the provisions for expanding the capacity of the plant.

Jan 1, 1972

By Megan Badonie, Devlon Shaver, Evan J. Owen, Virginia T. McLemore, Jakob Newcomer

Critical minerals are becoming more important in our technological society because they are used in many of our electronic devices, batteries, and magnets. In New Mexico, low to moderate concentrations of critical minerals are found in Late Cretaceous coal and related strata in the San Juan and Raton Basins. These rocks are being characterized as part of the DOE’s CORE-CM (Carbon Ore, REE, and Critical Minerals) program. The New Mexico coal, humate, and clinker deposits are relatively low in REE (<325 ppm TREE), Li (<90 ppm), V (<168 ppm), Co (<51 ppm), Ni (<108 ppm), Zr (<557 ppm), and many other critical minerals compared to normal economic deposits. Some of these rocks are enriched in Al2O3 (<40%) and Sr (<3740 ppm), both critical minerals. Common minerals hosting the critical minerals in these rocks include clay minerals, zircon, and rutile/anatase. As the demand for some of these elements increases because of increased need and short supplies, the dollar value per ton of ore rises, enhancing deposit economics. Ultimately, economic potential will most likely depend upon production of more than one commodity, maybe even from coal, humate, and clinker deposits.

Feb 1, 2024

By Yi Luo

A massive roof fall occurred in a small room-and-pillar coal mine. The roof falls occurred under a barrier pillar in a closed coal mine located a short distance above the active mine. The extensive fractures connected the active mine with the old mine, turning them into a “combined mine.” Since completely sealing off the roof fall area is prohibitively expensive for the mine, ventilating the connected old mine became the only option. A comprehensive investigation was conducted to understand the atmospheric condition in the old mine and to find an efficient way to ventilate the “combined mine.” A set of studies involving geology, gas content, pillar stability and mine subsidence were performed to explore whether the closed mine is filled with an explosive air-methane mixture. The air quantity measurement data were used to determine the resistance of the air path formed through the fractured zone. Observations and measurements made from a tour to the underground and mine surface enabled the formulation of simple but effective ways to ventilate the old mine. The ventilation network analysis also suggested methods of control, so that sufficient ventilation air can be directed to the two parts of the old mine.

Jan 1, 2010

By F. H. Nehl

The U.S. Bureau of Mines investigated the selective electrowinning of Ag and Au from cyanide solutions contaminated with Cu with the goal of decreasing the amount of Cu co-deposited. Decreasing Cu co-deposited will reduce refinery costs. Direct current was applied to the cell in pulsed and square wave voltages at 0.7 A?h per 150 mL of solution. Times tested for each cycle ranged from 1 to 10,000 ms. Graphite, lead, and stainless steel were evaluated as electrode materials. Square wave e1ectrowinning at 70? C gave the best separation of Ag and Au from Cu. Applying 2.5 V during the duty cycle, 0.0 V the rest of the period, a duty cycle of 10 to 30 pct, and a period of 100 ms to 1,000 ms gave the following results: Ag concentrations decreased from 34 µ g/mL to 0.1 µ g/mL, Au concentrations decreased from 54 µ g/mL to 0.2 µ g/mL, and Cu concentrations remained almost constant at 560 µ g/mL.

Jan 1, 1993

By Biswajit Samanta, Rahul Kumar, Pranjal Pathak

The Open Pit Mine Production Scheduling Problem (OPMPSP) is a complex optimization problem that seeks to determine the best sequence for extracting mineralized material from the ground in order to maximize the Net Present Value (NPV). This process must take into account various capacity constraints, such as mining rates, processing limits, stockpiling capacities, blending requirements, and precedence constraints, which dictate the order in which blocks can be extracted. Traditionally, the OPMPSP has been formulated as a mixed integer programming problem, employing binary and continuous variables to represent the extraction of each block. However, this approach has limitations, particularly when it comes to addressing the stockpiling issue. In response, some researchers have proposed mathematical models, which offer a more accurate representation of the problem but come with their own set of challenges. In this study, an alternative approach to tackle the OPMPSP with stockpiling by employing constraint programming (CP) is explored. The method was carefully tested on the Newman1 dataset from the well-known Minelib library. The results show that the CP-based model obtained a production schedule having about 2.69 % higher NPV than the NPV of the solution, which is recorded in the Minelib Library.

Jun 25, 2023

By K. J. Reid

With the current trends of increasing costs and decreasing head grades the mineral industry is no longer operating in very high profit areas and has been forced to pay greater attention to the application of modern technology. Although here are many technological advances to the credit of the industry in recent years there are still many processes being operated in the traditional manner and still many areas awaiting the application of methods which have been proven in other industries. Compared with the chemical industry the mineral industry is seriously ageing in the general areas of process analysis and process control, more so than can be justified by the complications arising from having to deal with particulate systems with properties far different from ideal, or even non-ideal, liquid systems. One area in which there has been a remarkable lack of application in the Mineral industry is that of analog computation and the authors feel that there is considerable scope for the use of the analog computer in studying mineral industry processes. The paper outlines the basic principles and features of the analog computer and describes its role as a simulation tool in some engineering and mineral processing systems.

Jan 1, 1972

By Diler Katircioglu-Bayel

This study aims to investigate the effect of combined mechanical and ultrasonic milling on the size reduction of talc. Firstly, the talc sample was wet ground in a stirred media mill for five different times (30, 60, 90, 120, and 150 min), and the optimum result was subsequently achieved with treatment by ultrasonication. The effects of amplitude (20, 35, and 50 μm), solid content (2.5, 5, 7.5, and 10%), and sonication time (60, 120, and 240 min) on the sizes of the final product were investigated. The pre-milling by wet grinding caused a decrease in the grinding resistance of talc. Sequential ultrasonic treatment, which was applied to the talc sample, generated smaller particles in comparison to those acquired by stirred media milling alone. Experimental results were assessed based on the product particle size (d10, d50), reduction ratio, and specific energy consumption. Submicron particles prepared by ultrasonic treatment were perfectly stable compared to stirred media milling alone as investigated in terms of particle size. In addition, the effects of mechanical and ultrasonic milling on structural properties of talc particles were characterized by XRD analysis.

By John C. Nigro

Bench scale and pilot plant research was conducted using dolomites (CaO,MgO) lime as the basic additive in the preparation of self-fluxed pellets from a typical magnetic taconite concentrate (5.57 S_2). The specific objective of this investigation was to ascertain the viability of the magnesia lime pellets in high temperature oxidizing and reducing atmospheres. Pellet basicity and induration temperature were major parameters affecting fired pellet quality; temperatures ranging from 1,200° to 1,250" C appeared to be the most favorable for production of self-fluxed pellets with basesities (B) above 1.0. Comparison of the mechani¬cal and metallurgical properties of regular (acid) and self-fluxed pellets (B 1.55) produced under similar conditions in a modified grate pelletizing machine showed that the self-fluxed pellets were more resistant to abrasion and to high and low temperature reduction disintegration, an important consideration in commercial application. The Plus 3 mesh Linder index increased from 68 percent (regular pellets) to over 90 percent (self-fluxed pellets). The reducibility and swelling indices of the self-fluxed pellets were found to be comparable to the regular pellets.

Jan 1, 1972

By James C. Barker

Alaska?s known mineral endowment includes some of the largest and highest grade deposits of various metals, including gold, copper and zinc. Recently, Alaska has also been active in the worldwide search for sources of rare earth elements (REE) to replace exports now being limitedby China. Driven by limited supply of the rare earths, combined with their increasing use in new ?green? energy, lighting, transportation, and many other technological applications, the rare earth metals neodymium, europium and, in particular, the heavy rare earth elements terbium, dysprosium and yttrium are forecast to soon be in critical short supply (U.S. Department of Energy, 2010). The REE, accompanied by other high field strength metals (such as Nb, Zr, Ti, Th, W), are associated with alkaline complexes of the Hogatza Belt in northwest Alaska; peraluminous tin-granites of the Ruby batholith in central Alaska and the Porcupine plateau in the northeast; and peralkaline intrusive complexes in the southwest Alaska Range west of Anchorage, and on Prince of Wales Island in southeastern Alaska. Limited evidence suggests that the heavy REE are associated with deposits that became more highly evolved by late hydrothermal processes.

Jan 1, 2012

By Paul W. Johnson

Chemical mining is the in situ extraction of metals from ores located within the confines of a mine (broken or fractured ore, stope fill, caved material, ores in permeable zones) or in dumps, prepared ore heaps, slag heaps, and tailing ponds on the surface. These materials represent an enormous, untapped, potential source of all types of metals. The field of chemical mining, now in its infancy, encompasses the preparation of ore for subsequent in-place leaching, the flow of solutions and ionic species through rock masses and within rock pores, the leaching of minerals with inexpensive and regenerable lixiviants under prevailing conditions of the in-place environment, the generation and regeneration of such solutions, and the recovery of metals or metal compounds from the metal-bearing liquors. It is not inconceivable that eventually our ore reserves will consist largely of low-grade, refractory, and inaccessible new deposits and low-grade zones near previously worked deposits, caved and gob-filled stopes, waste dumps, tailing ponds, and slag-heaps. Chemical mining promises economic recovery from these types of deposits. Before it can come of age, however, a much better understanding is needed concerning its chemical and physical aspects.

Jan 1, 1967

By B. Hearn, Malcolm J. McPhersqn

Since 1993 Inco Ltd. has been using wet shotcrete at Stobie Mine. Through an evolving process the mine has reduced the thickness and fiber content of its steel fiber reinforced (sfr) shotcrete. However, the shotcrete support is used without any other type of ground support. A process referred to as bolt less shotcrete. Boltless shotcrete is used as the primary ground support method in development headings when the sub level caving front passes through the development drifts which now serve as migrating ore draw points. Although there are references of drifts and tunnels supported by shortcrete only, written accounts are rare. The empirical nature of most underground support designs makes them of limited value in a boltless environment. Considerable amounts of material testing and insitu trials have been completed in order to estimate material property strengths. Material testing, for adhesion, flexural strengths and compressive strength along with observational insitu data have been used to evaluate the performance of shotcrete. Punch tests on panels have also been undertaken in order to gain insights on the limitations of the two dimensional testing common to the laboratory. All these design aspects have been successfully utilized to design an efficient ground support process.

Jan 1, 1998

By John E. Feddcck

New York City&apos;s $360 million North River Water Pollution Control Project is part of New York State&apos;s plan to clean up the Hudson River. The project is to provide a sewage treatment facility capable of accomodating a peak waste water flow of 330 MGD which will in great measure eliminate the 192 MGD of raw sewage that N. Y. C. discharges into its surrounding waters. Eleven miles of intercepting sewer lines must be constructed along the west side of Manhattan Island to service approximately one-half of the island. The first contract award was for a 4134 ft. sewer tunnel with a finished inside dimension of 16&apos; x 16&apos;. This main intercepting sewer will feed a sewage treatment plant located on and adjacent to the Hudson River. The tunnel is parallel to the river and is located under 12th Avenue between 125th Street and 143rd Street. The Penn- Central Railroad tracks are above and just to one side of the tunnel location. The working tunnel diameter is 21 ft. and numerous problems of support, mining method, and ground control have been encountered. (see Dwg. 1)

Jan 1, 1970

By F. Woller

The territory of Czechoslovakia is well endowed in deposits of a variety of industrial minerals. At present, 29 different types of industrial minerals are mined from some 600 individual deposits in Bohemia and Moravia only. About half of those production centres involves structural materials like aggregate and common brick clays and loams. A significant proportion of industrial minerals produced in Czechoslovakia are exported. Destinations of main products are shown in Figure 1. Production of industrial minerals in Czechoslovakia has a long history. Glass has been produced since the 14th century, sulphuric acid since 1578, graphite since 1750, and chinaware since 1790, to name just a few; but most of the present production comes from deposits developed during the past forty years. For a variety of reasons, only about 30 per cent of registered and explored industrial minerals deposits in the country are in production (Table 1). Two of the reasons may be the complexity of processing or conflicting interests of parties involved, but lack of market research, investment funds, or processing capacity have also had an impact on the level of utilization of the resource base.

Jan 1, 1992

By Nicolin Govender, Pramod Kumar, Raj Rajamani

Mill power models have been used in a variety of ways in industrial practice since power directly equates to throughput and fineness of ground product. We first start with Hogg-Fuerstenau Power Model and show how this model successfully predicted the power draw of many grinding mills in several mining operations. Then, we show how this model was on the verge of being able to predict the influence of lifter design on power draw. Next, we describe the discrete element model and how it overcame the issues faced by the previous power model. Using a DEM software known as Millsoft, we show the influence of lifter design geometry on power draw and analyze the power draw of rubber lifters versus the steel lifters via several case studies. As years passed, the two-dimensional discrete element model imbedded in Millsoft is superseded by three-dimensional discrete element method. Due to the gigantic computational power of graphic processing units, new computational codes that can do the tumbling motion along the entire length of the mill has come about. Here, we show the predictive capability of Blaze-DEM for ball and SAG mills.

By Evan Dressel, Mark S. Diederichs, Kathy Kalenchuk

As hard rock mining develops deeper over time, there is an increasing need to predict the spatial and temporal distribution of adverse seismogenic rockmass reaction to mining. Real-time monitoring and feedback of mine data are used to tactically manage risk associated with induced-seismicity; however, strategic risk management requires reliable tools for forward predictions of seismic hazard. The forward prediction of seismic hazard is strengthened by understanding of potential seismic intensity, which often relies on well calibrated mine-wide numerical models. This paper uses a case study to explore how future seismogenic potential and the nature of future seismicity can be domained according to numerically predicted stress-strain paths at past seismic event locations. Delineation of high confinement seismogenic volumes vs. lower-confinement, high-strain seismogenic volumes at the mine-scale can be achieved, based on a loading and unloading stress path analogue, to refine understanding of seismic intensity. Practical qualitative and quantitative methods to achieve this delineation will be demonstrated. Once seismogenic mode (high-stress vs. high-strain) is identified, detailed analyses of seismic source parameters demonstrates change in seismic hazard between the domained volumes.

Apr 26, 2022

By Henk L. C. Meuzelaar

Most of us are aware of the relationship between the golden-yellow resin spots on Upper Cretaceous Wasatch Plateau coals and fossil tree resins (?amber?). Nevertheless, confusion remains about the exact chemical composition and structure of commercial coal resin preparations as well as their observed heterogeneity. In order to arrive at a more detailed chemical description we need to distinguish between micropetrographic, organic geochemical and process technological definitions of coal resins, which may include substantial quantities of constituents unrelated to fossil tree resins. New information on composition and origin obtained by Curie-point pyrolysis/evaporation in combination with isobutane chemical ionization mass spectrometry, as presented in this paper, points to the presence of four more or less distinct resin components: (1) a sesquiterpenoid polymer; (2) sesqui-and triterpenoid monomers and dimers; (3) a suite of triterpenoid alcohols, ketones and acids; and (4) a series of increasingly aromatized hydrocarbons with naphthalene and picene type skeletons. Moreover, a strong similarity is found between the composition of recent Dammar resin and fossil Wasatch Plateau coal resins. Some of the technological implications of these findings and the consequent need for a more precise chemical definition and nomenclature are discussed.

Jan 1, 1990

By Evan J. Owen, Virginia T. McLemore

The Zuni Mountains, located in Cibola County, New Mexico is an uplifted area that exposes Proterozoic igneous and metamorphic rocks overlain by Permian and younger sediments. Sedimentary-hosted Cu deposits and fluorite veins in the district have recorded production, but other deposits exist. Proterozoic ultramafic rocks may host Ni and PGE. A recent regional stream sediment survey collected 76 samples as part of an exploration geochemistry course at New Mexico Tech with the goal of assessing the critical minerals potential of the district. Whole rock and trace element chemistry of the sediment samples (<2 mm) show a variety of critical minerals possibly worthy of future targeted exploration including up to 700 ppm As, 2100 ppm Ba, 26 ppm Bi, 25 ppm Co, 640 ppm Cu, 145 ppm Ni, 110 ppm Sb, 170 ppm V, and 500 ppm Zr. Positive correlation between Bi, As, Cu, and Sb suggest that these critical minerals are found together within copper veins related to shear zones in the district. Samples collected from streams that drained outcrop of mafic and ultramafic rocks were found to generally contain more Ni, Co, and V. Samples elevated in Ni will be reanalyzed for PGE.

Feb 1, 2025

By J. Hallowell, M. Conley, R. Cook

Inflatable friction rock bolts (IFRBs) are often considered temporary ground support due to their susceptibility to weakening from corrosion. The effective service life of an IFRB can be difficult to estimate due to the multitude of factors that affect the rate of corrosion. Some mine sites have experienced several-year-long service lives of IFRBs without issue, while others experience corrosion-related falls of ground only weeks after installation. The most common industry method of assessing bolt performance is by pull testing the fixture. However, due to the IFRB’s ability to mobilize its full tensile capacity with less than 2 feet of anchored length, corrosion along the bolt at depths greater than 2 feet from the collar cannot be identified using this approach. Alternatively, reinflation testing is a simple and non-destructive method of evaluating the condition of an entire bolt length for breaches in the bolt wall. This can be particularly useful when assessing the extent of corrosive conditions within a particular mining area where instabilities have already occurred and the condition of nearby bolts is unknown, or when re-entering historic mine workings which have not been monitored.

Feb 1, 2023

By G. F. Revey

Most commercial explosives contain 70 to 94% ammonium nitrate, by weight. When portions of these explosives end up in shot rock and ore, through spillage or incomplete detonation, ammonia and nitrates leach out of them and into ground water. In recent years, State and Federal regulators have been applying more stringent water quality standards, particularly at new mines and development projects. Bulk ANFO, a mixture of ammonium nitrate and fuel oil, is the explosive of choice at most mines, when mining conditions allow it. ANFO use is desired because it less costly than other explosives, but when spilled it dissolves readily in water. Several case histories in the United States and Canada show a clear connection between uncontrolled losses of bulk explosives and high nitrate levels in mine effluents. Mining companies have tried several approaches to reduce ammonia and nitrate levels in groundwater. They either control explosive losses, or they treat mine effluents at the end-of-pipe. This paper addresses the former solution --controlling explosive losses. For both packaged and bulk explosives, guidelines designed to limit losses during storage, handling and use, are described in detail.

Jan 1, 1995