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By L. K. Holder

The White King / Lucky Lass Superfund site consists of two former uranium mines in south-central Oregon. The remedy included consolidating two large mining overburden stockpiles that contained low levels of radioactivity and heavy metals by moving over 700,000 cubic yards of material and then capping the combined stockpile. An innovative armored cap design was used to minimize the stockpile footprint and thereby prevent disturbing existing wetlands. In addition, the stockpile was designed to merge into the surrounding topography. The remedy also included stream restoration and development of new wetlands. The stream was returned to its pre-mining channel, with the addition of hydraulic features to create new wetlands. The wetlands have greatly enhanced the ecological value of the remedy and the site.

Feb 23, 2014

By L. Zhou, J. P. Rider, T. W. Beck, J. A. Organiscak, Y. Zheng

The U.S. National Institute for Occupational Safety and Health (NIOSH)’s Pittsburgh Mining Research Division (PMRD) recently developed a series of models using computational fluid dynamics (CFD) to study gas distribution around a continuous mining machine with various fan-powered flooded bed scrubber discharge configurations in an exhaust curtain working face. CFD models utilizing species transport model without reactions in FLUENT were constructed to evaluate the redirection of scrubber discharge toward the mining face rather than behind the return curtain. The study illustrates the gas distribution in the slab (second) cut. The following scenarios are considered in this study: 100 percent of the discharge redirected back toward the face on the off-curtain side; 100 percent of the discharge redirected back toward the face, but divided equally to both sides; and 15 percent of the discharge redirected toward the face on the off-curtain side, with 85 percent directed toward the return curtain. These models are compared against a model with a conventional scrubber discharge where air is directed away from the face into the return. The models were validated against experimental data, proving to accurately predict sulfur hexafluoride (SF6 ) gas levels at four gas monitoring locations. This study includes a predictive simulation examining a 45° scrubber angle compared with the 23° angle for the 100 percent redirected, equally divided case. This paper describes the validation of the CFD models based on experimental data of the gas distribution results.

Jan 1, 2017

By L. Zhou, J. P. Rider, T. W. Beck, J. A. Organiscak, Y. Zheng

The U.S. National Institute for Occupational Safety and Health (NIOSH)’s Pittsburgh Mining Research Division (PMRD) recently developed a series of models using computational fluid dynamics (CFD) to study gas distribution around a continuous mining machine with various fan-powered flooded bed scrubber discharge configurations in an exhaust curtain working face. CFD models utilizing species transport model without reactions in FLUENT were constructed to evaluate the redirection of scrubber discharge toward the mining face rather than behind the return curtain. The study illustrates the gas distribution in the slab (second) cut. The following scenarios are considered in this study: 100 percent of the discharge redirected back toward the face on the off-curtain side; 100 percent of the discharge redirected back toward the face, but divided equally to both sides; and 15 percent of the discharge redirected toward the face on the off-curtain side, with 85 percent directed toward the return curtain. These models are compared against a model with a conventional scrubber discharge where air is directed away from the face into the return. The models were validated against experimental data, proving to accurately predict sulfur hexafluoride (SF6 ) gas levels at four gas monitoring locations. This study includes a predictive simulation examining a 45° scrubber angle compared with the 23° angle for the 100 percent redirected, equally divided case. This paper describes the validation of the CFD models based on experimental data of the gas distribution results.

Jan 1, 2018

By Marcel F. DeGuire

Pilot plant operations are described for the treatment of manganiferous zinc concentrates from the Gamsberg ore deposit in South Africa via conventional electrolytic zinc processing. Two methods were employed for the control of excess manganese ions in the pilot plant electrolyte involving (1) chemical oxidation and (2) anodic oxidation. The chemical oxidation method for manganese control was very successful. It also was found that the addition of manganese dioxide ore was not required for oxidation of ferrous iron during the neutral leach or jarosite precipitation steps. A new method (JAR process) for iron removal also was tested in the pilot plant.

Jan 1, 1978

By Arnold P. Szaj

There is no startling revelation to the fact that the mining industry as a whole is generally moving toward the use of larger equipment to process ores in quantities far greater than what was even considered a decade ago. Trucks and shovels have led the way in extra large machines and many other manufacturers have followed suit in the development of so-called "supers" in their line of equipment. In order to keep pace with the industry, crusher manufacturers have also enlarged the size of their equipment. There is now on the market, a Gyratory crusher capable of accepting a 72" diameter piece of ore. Primary jaw crushers have also increased in size. It is inevitable, therefore, that larger secondary cone crushers would also be required to complement the other equipment used to process these large quantities of ore. This super-size secondary cone crusher is the SYMONS 10 Ft. Cone Crusher. Until 1973, the largest cone crusher built was the 7 Ft. Extra Heavy Duty crusher, which is currently used in the majority of the mining operations throughout the world. The 10 Ft. crusher, when compared to the 7 Ft. Extra Heavy Duty Crusher, is approximately 1-1/2 times larger in physical dimensions; three times heavier; will accept a maximum feed size which is approximately twice as large; and will crush at approximately 2-1/4 times the rate of the 7 Ft. machine at identical closed side settings. It will be the largest cone crusher built in the world. At the present time, Rexnord's Nordberg Machinery Group has accepted an order for two 10 Ft. Standard cone crushers to be delivered to an iron ore mine in South Africa in early 1975.

Jan 1, 1973

By P. W. Finck

Detailed mapping, using a large diameter diamond-drill in conjunction with high resolution reflection seismics, has increased known resources of kaolin clay and glass-grade silica sand from scattered deposits generally < 1 km2 to large areas of Cretaceous valley fill up to 130 m thick. Detailed chemical and physical analysis of drill core is presently underway. Silica sand deposits intersected in this study are up to 99.4 % SiO2 without beneficiation. Light grey to white kaolin clays identified by XRD and DT A have concentrations values (without beneficiation) up to 47.28% SiO2, 37.44% Al2O3, 0.45% Fe2O3, 0.49% K2O, 0.07% Nap, 0.07% CaO and 0.39% MgO.

Jan 1, 1996

Industry and regulatory agencies have requested guidance on safe blasting near transmission pipelines. The U.S. Bureau of Mines and AMAX Coal Company have studied surface coal mine overburden blasting near four steel and one PVC pipe-line of 15 to 5l-cm diameter, monitoring vibration, strain, and pressure. Unlike tests simulating construction blasting, these were up to 1000 kg per delay in 3l-cm blastholes. Worst case comparisons showed that 12.7 cm/s blasting vibrations produced strains about 1/4 that of pressurization and 10-18 pct of the ultimate tensile strength. No failures occurred from blasting as close as 15 m which produced vibrations over 60 cm/s.

Jan 1, 1994

By Joseph Padgett

Of all the fossil fuels produced in the U. S., coal is by far the most abundant. U. S. reserves amount to an estimated 1.5 trillion tons, 2,500 times the 600 million tons produced in 1970. Although it would not be possible to recover all of this coal economically with current mining technology, a significant portion would be available given the proper circumstances. With existing technology, approximately one-eighth of these reserves is accessible, an amount which would last for several hundred years at the 1970 level of production. On the face of it, this substantial reserve should go a long way in meeting the Nation&apos;s energy needs. But coal offers special problems. As additional coal is mined and then burned, there are increased costs to the Nation&apos;s land, water, skies, and health. Hence, coal poses a dilemma because of its dual status as one of our most abundant domestic fuels and as one of our major sources of environmental degradation. Against the benefits that would be chalked up in the areas of national security, balance of trade, and economic well-being from the increased use of coal, we must enter on the debit side of the ledger the increased environmental cost. This paper reviews the use of U.S. fossil fuel, the drawbacks of coal as an energy source, the means being developed to overcome these drawbacks, and the background behind the present sulfur emission regulations relative to coal combustion. It also discusses in detail the Federal Environmental Protection Agency&apos;s (EPA&apos;s) current policies to ensure the continued use of coal as a major source of energy for fossil-fuel fired power plants.

Jan 1, 1973

By T. M. Gurr

Large quantities of phosphate rock are mined and processed in Central Florida (Figure 1). The phosphate rock from the mines is further processed in "chemical plants" to produce phosphoric acid (Figure 2). A by-product of the processing&apos; of the phosphate rock to produce fertilizer chemicals is an impure form of gypsum referred to as phosphogypsum. For each ton of phosphate rock processed, approximately 1.5 tons of phosphogypsum is produced (Figure 3). The typical method to dispose of this by-product gypsum is to stack it in large piles, locally referred to as gypsum stacks or gypsum fields (Figure 4). These gypsum stacks have been the focus of many studies in recent years in an attempt to identify the potential for ground water and/or air pollution associated with the stacks. This paper attempts to discuss some of the ground water impacts and current attempts to minimize these impacts.

Jan 1, 1990

By S. H. Seyedein, Hamed Tavakkoli, Mohammad Reza Aboutalebi, S. N. Asharafizadeh

The liquid–liquid extraction behavior of lutetium from different acidic solutions was investigated using two extractants, D2EHPA and PC88A, in kerosene. Lutetium extraction reactions with D2EHPA and PC88A from HNO3 and H2SO4 solutions were chemically and thermodynamically analyzed. It was found that each Lu cation was complexed with six monomers of the organic extractant and released three protons. Simultaneously, the Lu cation was instituted in the P–O–H group of the extractants. Thermodynamic analysis of reactions between extractants and acidic solutions showed that the D2EHPA-HNO3 system is the most favorable for extracting lutetium. It is noted that the calculated equilibrium constant of the reaction in this system was approximately six times larger than that of the D2EHPA-H2SO4 system. However, the value of the equilibrium constant for the D2EHPA-HNO3 system was evaluated to be approximately 200 times greater than that of the PC88A-HNO3 system. Therefore, one can conclude that the extraction behavior of lutetium is more influenced by the extractant type than the solutionmedium. The synergistic effect of different mixtures of extractants on the solvent extraction of lutetium was also examined, and the highest synergistic factor was obtained for a binary mixture of PC88A:D2EHPA at the ratio of 4:1 for both aqueous solutions.

Mar 15, 2021

By J. Brad Dalton, Sam Vance, Trude V. V. King, Roger N. Clark, Raymond F. Kokaly, Gregg A. Swayze, Dana J. Bove

Visible-wavelength and near-infrared multispectral image cubes for the Animas River Watershed from Hermosa, Colorado to the headwaters at Animas Forks, Colorado were acquired on June 18, 1996 using the Jet Propulsion Laboratory&apos;s AVIRIS (Airborne Visible and InfraRed Imaging Spectrometer) instrument (Green et al., 1998). These image cubes have been analyzed using the USGS Tetracorder V3.4 implementation (Clark et al., 1995), an expert system which utilizes a database of more than 300 laboratory spectra of endmember minerals and mineral mixtures to generate maps of mineralogy, vegetation coverage, and other material distributions. Major iron-bearing, clay, carbonate, and other minerals were identified along with several minerals associated with acid-generating hydrothermal systems including pyrite, jarosite, alunite and goethite. Additionally, distributions of alkaline minerals such as calcite and chlorite indicate a relation between acid- buffering assemblages and stream geochemistry within the watershed.

Jan 1, 2000

By Philip A. Bucci

The Florida phosphate industry successfully uses froth flotation to concentrate phosphate in: the particle size range of approximately 28 to 150 mesh. However, as recently as 1965, coarse particles in the range of 14 to 28 mesh generally had not been beneficiated by conventional flotation methods at recoveries high enough to be considered adequate. It has been customary to upgrade this coarse material; by "agglomerate flotation" or "skin flotation" using belts, tables or spirals. While these devices have proved commercially effective, their capacities are much lower than those of froth flotation cells. To determine whether coarse phosphate material could be recovered successfully by froth flotation, Armour Agricultural Chemical Company began a series of pilot and plant tests; in April 1965. Objective of the tests was to compare over-all performance of a froth flotation cell design relatively new to the phosphate industry with results from the belt circuit at the Bartow, Fla., plant.

Jan 1, 1966

By K. V. Raj, A. Miller

"Workers at mineral processing facilities are often exposed to high levels of dust generated when ores are processed. Crushing, grinding, screening, and other processes generate large quantities of dust, which can exceed the threshold VALUES (prescribed by the Mine Safety and Health Administration (MSHA). Many ores contain quartz (silica), which has been known to cause serious health problems in workers over time. Given the structure of mineral processing plants, the airflow regime is not coherent inside the building, which may lead to multiple recirculation zones. These recirculation zones can trap dust, and concentrations of dust can then rise over time. Therefore, there is a need to understand the airflow phenomenon that occur inside of mineral processing facilities and how these occurrences interact with the dust generation processes to identify zones of potentially high dust concentration. Computational fluid dynamics (CFD) modeling can give a better understanding of the airflow and help recommend designs and methods to mitigate the high dust concentrations in a mineral processing plant. This paper presents the CFD modeling of airflow inside of a mill building to demonstrate airflow patterns that will affect the generation and subsequent dispersion of dust due to crushing, grinding, and other activities. This study was conducted by researchers from the National Institute for Occupational Safety and Health (NIOSH). INTRODUCTION In a mineral processing facility, minerals go through various mechanical processes in order to reduce their size for separation of economic minerals from gangue minerals to produce a final marketable product. This research, conducted by the National Institute for Occupational Safety and Health (NIOSH), focuses on ore mills in metal and nonmetal mining (MNM) operations, but the applicability of the approach will be valid for any large structure where workers are exposed to airborne contaminants. The processes of crushing, grinding, cleaning, drying, and product sizing in these facilities generate a large amount of dust, creating hazardous conditions for the workers in these facilities. This is highlighted by the fact that MSHA sampling data for the years 1997–2012 indicate that 12.3% and 15.9% of the gathered samples were over 100 µg/m3 for silica for metal and nonmetal mills, respectively [1]. Mineral processing operations typically use some type of engineering control to address their most significant dust sources. Engineering controls include such approaches as bag-house-type dust collectors, scrubbers, and electrostatic precipitation [2]."

Jan 1, 2018

By Doandy Yonathan Wibisono

Shotcrete is a versatile and widely utilized rock support material in mining and civil engineering projects due to its adaptability, strength, and efficient application. It immediately stabilizes rock surfaces, effectively controlling loose materials and preventing rockfalls in underground excavations. This paper focuses on assessing and analyzing data from observations of nozzlemen (shotcrete sprayers) during primary ground support activities in an underground mine. The study highlights the importance of nozzlemen’s skills in ensuring the quality of shotcrete application, which is critical for underground mining operations’ structural integrity and safety. A comprehensive training program and field support were implemented to enhance the nozzlemen’s proficiency. The training set covered theoretical knowledge and practical techniques to improve shotcrete application daily. Proficiency improvement was assessed using quantitative metrics, with rebound percentages decreasing by 5–14% as nozzleman competency increased. The results of this initiative showed significant improvements in shotcrete quality, including increased efficiency, reduced waste, and fewer reworks or rehabilitations. The findings aim to contribute to a broader understanding of best practices in shotcrete application and nozzlemen training, ultimately enhancing ground support application measures in the mining industry.

Feb 1, 2025

By P. Amelunxen

Over the past several years, the combination of higher energy and steel costs and the recent commercial deployment of high-pressure grinding rolls (HPGR) technology in hard rock mining have led many multinational mining companies to evaluate the suitability of HPGR technology for their particular comminution circuits. HPGR technology is perceived to require a higher capital investment while delivering lower long-term operating costs. This paper undertakes a critical evaluation of this perception. By evaluating the capital and life-of-mine operating costs of competing circuit designs for soft, medium and hard ores, the HPGR break-even point can be identified, at which the incremental capital cost of an HPGR circuit is equivalent to the net present value of the projected operating cost reductions. For ores with hardness parameters above the break-even point, HPGR circuits could offer economic benefits, while for softer ores, SAG mill/ball mill/pebble crushing (SABC) circuits are likely to be more economical and energy efficient. This evaluation considers both an SABC reference circuit and a traditional stage crushing configuration. Other influential factors are also discussed.

Jan 1, 2011

By William Gleason

While a fleet of 100 t (110 st) haul trucks were busy removing overburden from the open pit mine in the distance, a host of dignitaries, including congressmen and California state representatives, gathered for Molycorp?s official groundbreaking ceremony at the Mountain Pass Mine on April 20. The mine, recognized as arguably one of the richest rare earths deposits in the world, is at the center of Molycorps? strategic ?Mine to Magnets? plan. It aims to secure America?s future supply of rare-earth-dependent technologies by developing a strong domestic rare earth industry. Molycorp identifies rare-earth-dependent technologies as those that cannot be produced without rare earth materials. The list of these technologies is long and growing. It encompasses everything from personal electronics and batteries for hybrid cars to permanent magnet generator wind turbines and national defense applications.

Jan 1, 2011

By C. D. Secrest

Visiting Spring Canyon, a historic coal mining district near Helper, Utah, I was impressed by the great accomplishments that had taken place there. A tour book of the region tells of a period that began in the early 1900&apos;s, when the land was still very much the Old West, when settlers lived out their lives in coal company towns and produced a resource that was to build a nation (Cunningham, F., 1990). Between 1912 and the early 1970&apos;s, 11 mines had come and gone in that narrow canyon less than 15 kilometers long. Spring Canyon is a historic district now, but I could not dwell too long on the richness of its history. I was there to look for evidence of PCBs.

Jan 1, 1993

By William G. Pariseau

The flexure of geologic strata, a phenomenon of inter- est to geologists and mining engineers alike, is examined as a sheet bending problem&apos; in Coulomb plasticity. Formulae for the distribution of stress, strain and displacement increments, volume change, change in the length of the central surface and power of dissipation, as well as for the neutral surface shift are given. Strains of any magnitude are considered. The analysis shows that deeply buried strata may bend and develop "tensile" cracks under generally compressive states of stress. It is also shown that bed separation and high capacity props are desirable in mechanized longwall mining, a result in keeping with operating experience. Although speculative at this time, the analysis provides a rational working hypothesis as regards the problem of strata flexure and control.

Jan 1, 1968

By O. M. Arafat, J. A. Finch

"The Functional Performance Equation calculated from a plant grinding survey defines two distinct ball mill circuit efficiencies and how they relate to total production rate through the target grind size. The survey data are also used to calculate a complete ball mill size distribution model, represented by the energy specific grinding rates, not just through the target grind size, but through all the size classes. Cyclone separation performance is represented by individual size recoveries to underflow. When these two unit operation performances are entered into the circuit modelling program (Streamline™), along with the circuit feed rate and size distribution, all the circuit survey size distributions and mass flows are perfectly regenerated by the program. The many issues associated with the historical Epstein (breakage-selection) models are eliminated. Once the circuit program is populated, pump and cyclone performance changes can be evaluated using a step-by-step procedure in order to maximize Classification System Efficiency. Mill water use and media sizing opportunities are also diagnosed in order to maximize Mill Grinding Efficiency at the size of interest. An example is provided. This circuit analysis and modelling system, and related training, is provided through a web-based application. INTRODUCTION Since its development (McIvor, 1988), the Functional Performance Equation for ball milling has facilitated new understanding of industrial circuit cause and effect relationships, leading to significant strides in operational performance. Success stories of this refreshing approach to plant circuit performance improvement are now too numerous to list. Finch and McIvor (circa 1986) also discovered that the Functional Performance “Mill Grinding Rate” at the size of interest was the same cumulative grinding rate that is calculated from mill feed and discharge size distributions using a first-order rate equation. By calculating these cumulative grinding rates for all screen sizes, a complete ball mill model is generated (as used by Finch and Ramirez, 1981). Others in industry, Hinde and Kalala (2009), for example, have noted the same. Lacking the complexity needed to maintain their interest, most researchers have ignored this model, broadly opting instead for Epstein’s (1948) characterization of grinding as a chemical reaction, combining “selection rate” and “breakage size distribution” functions. The much simpler ball mill model presented here has previously been incorporated into a proprietary circuit modeling program (McIvor, 2005) and used for plant improvement work (for example, see McIvor and Finch, 2007, and McIvor, 2014). Now, by combining this extremely business-friendly ball mill model with optimization criteria from Functional Performance Analysis, a circuit modeling system (including the needed supplementary steps to assure successful plant implementation of circuit design changes) is at the disposal of every plant metallurgist, grinding equipment/material provider, and circuit designer."

Jan 1, 2017

By Y. J. Wang

In the mathematical analysis of electrical networks, the electrical devices are often modeled using idealized network elements such as current sources, voltage sources, and resistors. An analogous approach is outlined here for the modeling of mine ventilation networks, which can be considered nonlinear resistive networks. The modeling technique proposed uses five basic (non-reducible) elements: the H element, the Q element, the D element, the R element, and the N element. These elements are characterized by their (a) pressure gain or loss, (b) air quantity, and (c) pressure-versus-quantity relationship, each of which may be known or unknown. In addition to the definition of the basic elements, the necessary conditions for which there exists a unique solution are discussed. This is performed using theoretical developments derived from electrical circuit theory and illustrated in example networks. The proposed procedures are useful in the solution and characterization of mine ventilation networks.

Jan 1, 1996