Search Documents

By G. M. Wilemon, J. G. Davis, R. G. Swanton, B. J. Scheiner

The US Bureau of Mines has conducted investigations on extracting phosphate values from wastes generated during the mining and beneficiation of phosphate matrix. These wastes may contain up to one third of the phosphate originally present in untreated ore. Samples of wastes were air-dried and leached using 93% sulfuric acid in the presence of methanol. Evidence for the formation of a calcium sulfate hemihydrate coating that hinders complete dissolution of phosphate is presented. Solid-liquid separations were enhanced when flocculation was effected using poly(ethylene oxide) (PEO) in conjunction with hydroxypropyl cellulose (HPC) or hydroxyethyl cellulose (HEC). A conceptual flowsheet for a proposed process using an acid-alcohol leaching technique is presented.

Jan 1, 1991

By J. McCreedy

The Ontario Division of The International Nickel Company of Canada, Limited, operates five underground mines and one open pit on the rim of the Sudbury Basin located in the Province of Ontario, 230 miles northwest of Toronto. Four of the mines, Frood-Stobie, Creighton, Murray and Garson, lie on the South range of the Basin within a 10-mile radius of the City of Sudbury; the fifth mine, Levack, is on the North range, about 30 miles northwest of the city. The ores are mined primarily for nickel and copper, the principal minerals being pentlandite and chalcopyrite. Other elements recovered from the ores in varying quantities are platinum, palladium, ruthenium, iridium, rhodium, cobalt, selenium, tellurium, iron, sulphur, gold and silver. In 1962, the total underground ore production was over 10,800,000 tons which was mined mainly by blasthole and caving methods with the remainder by cut-and-fill, square set, and undercut-and-fill techniques.

Jan 1, 1964

By Swan. J. D.

Repairing and replacing equipment damaged by corrosion and abrasion is a major cost throughout industry, especially in the coal mining industry. Careful study of corrosion and abrasion, and their causes and effects, often leads to the selection of alternative materials which can provide economies. What, actually, are corrosion and abrasion and how do they contribute to the cost of operating a coal-preparation plant? Furthermore, what can be done to alleviate corrosion and abrasion problems and thereby reduce operating costs? These questions will be answered in the following discussion, which will describe the destructive action of corrosion and abrasion and give several methods for controlling corrosion and abrasion losses, These methods include the substitution of stainless steel for carbon steel, the use of corrosion inhibitors, and the use of design to eliminate corrosion and abrasion. Examples will be given illustrating the benefits that have resulted in plant tests when these methods of controlling corrosion and abrasion were used.

Jan 1, 1970

By B. P. Spigarelli

To meet the growing need for CO2 capture and storage technology, Michigan Technological University is researching CO2 capture and storage using carbonate solutions. The objective of the present study was to increase the absorption rate of CO2 into the carbonate solution without reducing the absorption capacity of the solution. This approach used a polypropylene glycol methyl ether (PPGME) as a surfactant to chemically alter the gas bubble size. Experiments were conducted to study the absorption rate of CO2 at varying surfactant concentrations of 0, 0.12, 0.24, 0.36 and 0.48 g/L. Results showed that as the concentration of surfactant increased in solution, the absorption rate also increased. The CO2 absorption rate increased from 3.45 mmol/min CO2 at 0 g/L PPGME to 3.92 mmol/min CO2 at 0.48 g/L PPGME. This amounted to a 14% increase in the CO2 absorption rate with no decrease in absorption capacity of the solution.

By George A. Savanick

Borehole (slurry) mining, in which a tool incorporating a water-jet cutter and a downhole slurry pump mines phosphate through a borehole, was field tested in northeastern Florida as part of a Bureau of Mines program to increase the domestic availability of critical minerals. Approximately 1700 tons (1.54x106 kg) of phosphate ore were mined at 40 tph (10.1 kg/s) from a depth of 250 ft (76 m). The borehole was filled with water during mining for roof support and to assist slurry pumping. Underwater cutting was enhanced with an air-shrouded water jet. Mined cavities were backfilled to prevent subsidence after abandonment. Roof subsidence during mining was avoided only when the cavity was filled with water. Environmental monitoring before, during, and after mining included hydrological studies and measurements of water quality. Significant water quality changes occurred only in the zone being mined and were confined to the immediate area of the borehole.

Jan 1, 1983

By Arman Hazrathosseini, Ali Moradi Afrapoli

Fleet management systems (FMSs), as a pivotal part of any surface mining operation, need to evolve from conventional to intelligent systems because of both Mining 4.0 requirements and some shortcomings inherent in conventional methods. However, this novel transformation needs to be investigated technically and strategically. To this end, previously published research works on intelligent FMSs are explored to track the latest status of these third-generation frameworks within the surface mining context. Their underlying models are then compared in terms of five categories of allocation and dispatching features to pinpoint the technical gaps ignored. Having drawn the future lines of research, the present work then leverages the popular SWOT analysis method to outline the strengths, weaknesses, opportunities, and threats associated with the advent of these intelligent FMSs in mines of future. By and large, the analysis indicates that advantages outweigh disadvantages. Solutions are offered to address the existing weaknesses and threats.

Apr 1, 2024

By Dávila-Pulido. G., L. Magallanes-Hernández, F. López-Saucedo, J. Batista Rodríguez, A. Uribe-Salas

"This paper presents the results of tests performed to study the effect of slurry solids concentration on the behavior of gas dispersion in industrial-scale mechanical flotation cells. The experiments were conducted at five concentrator facilities run by a Mexican mining company, specifically in the rougher bank of the lead/zinc flotation circuits. Those mechanical cells having significant contribution to the performance of the circuit, that is, the cells that enable high recovery, were characterized. The measurement protocol enables measurement of the superficial gas velocity, gas holdup and bubble size, and sampling of the mineral slurry. The measured data indicate that bubble size and gas holdup decreases as the concentration of solids increases. IntroductionThe process of mineral concentration by flotation is based on contact between particles and air bubbles, the selective adhesion of hydrophobic particles onto the bubbles, and the rising of the bubble-particle aggregates to the surface of the flotation cell to overflow over the lip to form the concentrate. It is now accepted that the physical and chemical process variables that control the flotation of hydrophobic particles are closely related to gas dispersion (Schwarz and Alexander, 2005). Gas dispersion is defined by the superficial gas velocity, Jg (Torrealba-Vargas, Gomez and Finch, 2006), the gas holdup, eg (Tavera, Gomez and Finch, 1997), the bubble size, d32 (Dobby and Finch, 1986; Gorain et al., 1995; Hernandez-Aguilar et al., 2004) , and the bubble surface area flux, Sb (Manqiu and Finch, 1989; Manqiu, Finch and Uribe-Salas, 1991). In recent years, the advances that have been made in sensor technology have enabled the characterization of gas dispersion in industrial flotation cells with excellent results (Gomez and Finch, 2007). This technology advancement has allowed the gaining of a deeper understanding of such complex mechanisms as carrying capacity (Yianatos and Contreras, 2010), collection efficiency (Gorain, Franzidis and Manlapig, 1997; Massinaei et al., 2009) and bubble coalescence (Finch, Nesset and Acuña, 2008; Zangooi, Gomez and Finch, 2010)."

Jan 1, 2017

By P. Munjal

"Usage of Supercritical CO2 in place of high pressure freshwater has proven to be a potential breakthrough in the technique of fracturing. Tapping of carbon footprints from feasible sources like industries can be used to manufacture Supercritical CO2 required for fracking. Supercritical CO2, being less viscous than water, creates complex and coherent micro-fractures which can connect many more natural fractures greatly, increasing maximally the fractures’ conductivity leading to an increment in production. The better clean-up property of Supercritical CO2 provides auxiliary benefits of immediate evaluation of fracture zones, usage of an optimized quantity of mesh proppant and elimination of the need of swabbing. Also, Coal has a stronger affinity for CO2 than for CH4. When CO2 is present, CH4 on coal is replaced by CO2. This also ensures rigorous recovery of gas from the coal beds. Use of Supercritical CO2 will obliterate many problems as the CO2 used for fracturing is either sequestered beneath the crust or is recovered at the surface and reused. Therefore, injecting CO2 into coalbeds achieves not only enhanced CBM recovery, but also greenhouse sequestration underground. INTRODUCTION Coalbed Methane At various times in the geologic past, earth had dense forests in low-lying wetland areas. Due to natural processes such as flooding, these forests were buried underneath the soil. As more and more soil deposited over them, these dead plant remains were compressed. As the process continued the plant matter was protected from biodegradation and oxidation, usually by mud or acidic water. Under high pressure and high temperature, dead vegetation was slowly converted to coal. The omnibus process of formation of coal, thus, comprises of conversion of dead plant matter into peat, followed by its conversion to lignite, then sub-bituminous coal, after that bituminous coal, and lastly anthracite. This process of enrichment of coal as it is progressively forced deeper into an ambience with higher temperature and pressure involves biological and geological processes that take place over a long period and is called coalification. During coalification, large amounts of methane-rich gas are generated and stored within the coal on internal surfaces; hence comes coalbed methane. Coalbed methane (CBM), a gas formed as part of the geological processes that are responsible for the generation of coal, is adsorbed into the solid matrix of the coal during its formation process. Coalbed methane is distinct from a typical sandstone or other conventional gas reservoirs, as the methane is adsorbed and not absorbed. The methane is in a near-liquid state, lining the inside of pores within the coal. The open fractures in the coal that result from the liberation of volatile materials (and subsequent contraction due to the liberation) from the coal due to the high temperature and pressure conditions encountered, called cleats, may also contain free gas or can be saturated with water."

Jan 1, 2015

By J. L. Carr

Every year, severe injuries and fatalities occur when a miner is struck or pinned by a continuous mining machine, shuttle car, scoop or other piece of mobile mining equipment. Proximity detection systems offer a means to prevent these types of injuries and fatalities by sensing the presence of a miner and disabling machine motion. Although hundreds of these systems are installed and in use in operating coal mines, the influence that coal has on the electromagnetic fields associated with these systems has never been rigorously quantified. NIOSH researchers have conducted tests to measure whether the proximity of coal has a significant influence on a popular design of proximity detection system. The system tested utilizes a low frequency magnetic field generator that would be mounted on the mining machine. At the NIOSH Safety Research Coal Mine in Pittsburgh, researchers measured the performance of a simplified proximity detection system of this type first on the surface then underground at varying distances from a coal face. Analysis of these measurements shows that the presence of coal does not have a measurable impact. Disclaimer: The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Reference to specific brand names does not imply endorsement by the National Institute for Occupational Safety and Health.

Feb 27, 2013

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 I. Iwasaki, K. A. Smith, X. Cheng

A cathodic decomposition model was examined for both pyrrhotite and chalcopyrite in an attempt to analyze the formation of surface coatings in deoxygenated solutions at natural, near neutral pH. Combination potentials established between the mineral-grinding media pair were simulated by applying a potential of -0.455 V (vs. a standard hydrogen electrode) either to a pyrrhotite or to a chalcopyrite electrode. Chronoamperometry was used to study the polarization behaviors and alteration of mineral surfaces through cathodic processes. The kinetic parameters of cathodic decomposition of pyrrhotite and chalcopyrite were determined and compared. It was concluded that pyrrhotite decomposed faster than chalcopyrite in near-neutral pH solutions. Both minerals were then covered by a film consist¬ing mainly of iron hydroxides, which adversely affected their flotation.

Jan 1, 1999

By C. Tsatsanifos

Following closure of an old asbestos mine in Zidani, Kozani Prefecture, Greece, the geotechnical and environmental restoration of the tailings slopes was required. The geotechnical aspects of the restoration included the formation of gentler slopes to increase stability, in combination with drainage works for the same purpose. The environmental aspects of the restoration included covering the slopes with successive layers of soil in order to minimize infiltration of rainwater, and hence the potential for further transport of asbestos fibers, and to provide a suitable layer for revegetation of the slope. The paper presents results of slope stability evaluation using both limit equilibrium and finite element analyses and raises some issues related to reducing impacts to the geoenvironment when designing such restoration projects.

Jan 1, 2006

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 Roger L. King

Working in gassy ground conditions is an everyday occurrence for the U.S. coal mining industry. As tunneling operators begin to venture into projects that expose them to the additional hazard of potentially explosive atmospheres, lessons learned by the mining industry over years of experience should be transferred into this industry. This paper will present practices developed by the U.S. coal mining industry for dealing with the problem of excavating material in potentially explosive atmospheres. Procedures will be discussed that can be used to detect and quantify gas prior to mining that have application to the construction industry. Degasification or drainage practices, including predrainage from vertical and horizontal boreholes, will be discussed. Also, ventilation practices commonly used in the mining industry will be presented.

Jan 1, 1985

By C. Stephan, E. Weiss, J. Trackemas, M. Sapko

The National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Research Laboratory (PRL), in collaboration with the Mine Safety and Health Administration (MSHA), the mining industry, and seal manufacturers recently conducted a series of full-scale experiments within the underground experimental mine at PRL’s Lake Lynn Laboratory. The purpose of the experiments was to evaluate the explosion-resistant characteristics of several new seal designs for rapid deployment during mine emergencies. These seals can be deployed in 6 to 10 hr and are capable of withstanding explosion overpressures in excess of 140 kPa (20 psi). These novel seal designs use available mine materials, do not require conventional rib hitching, and, most importantly, can substantially reduce exposure time for coal miners during sealing and mine recovery operations.

Jan 1, 2003

By Charles C. Y. Chen, Duane R. Skidmore

Batch leaching of Ohio #1, Ohio #4A and Ohio #5 coals was conducted with the thermophilic. sulfur, oxidizing microorganism: Sulfolobus acidocaldarius. Four different size fractions of each coal, with median sizes of 508, 200, 90, and 49 microns, were subjected for 10 days to leaching in a 5% coal-water slurry at 72°C and a pH of 2. Release rates and extent of sulfate and iron I1 and I11 ions from the coals during the leaching process and distribution of sulfur forms (sulfate, pyritic and organic) in the coal samples before and after treatment were determined. Data indicated that Ohio #1 coal, with an initial sulfur content of 0.6%, showed no significant changes with leaching in total sulfur content or forms of sulfur. The Ohio #4A coal, with initial total sulfur content near 5%, yielded product, for sizes below 200 microns with 90% reduction of pyritic sulfur while the extent of organic sulfur removal varied with coal particle size. Results similar to those for Ohio #4A were observed on the Ohio #5 coal, which had an initial total sulfur content of 3% and a final sulfur content near 1%. The findings were interpreted in terms of basic biological, chemical and physical mechanisms.

Jan 1, 1989

By John Turner, John A. Gibson, David Cass

Contents A. Introduction B. Description of Robbins Company involvement in several of the English Channel Tunnel projects C. Identification of project requirements and comparison of TBM features D. Description of the manufacturers separate roles in the -235 (T-1) TBM E. T-1 performance to January 15, 1989 F. Summary

Jan 1, 1989

By Rudolph H. Jacobson

The leaching of heaps or sub-marginal waste ore dumps as it is practiced throughout the Southwest as well as other parts of the world, is the major method of secondary recovery of copper. In 1970, twenty percent of all domestic copper was produced by dump leaching operations (l). In recent years, this method has been successfully extended on a limited scale, for the recovery of uranium from low-grade ores (2). It is inevitable that this technique will be increasingly employed in metal production to satisfy the insatiable demand of our mineral based society. Although dump and heap leaching has been used effectively for some time (3) , its application has been more of an art than a science. Therefore, it is essential that we learn about the important factors and parameters affecting this versatile process so that we may make increasing use of this technique in the future. The dump or heap leaching process encompasses the preparation of ore for-subsequent inplace leaching, the flow of solutions and ionic species through porous rock masses, the leaching of minerals with inexpensive and, if possible, regenerable lixiviants under prevailing conditions of the inplace environment, and the recovery of metals from the pregnant liquors. It is evident that this comprehensive scope of dump or heap leaching falls under the realm of interdisciplinary science and engineering requiring the application of the principles of physics, mineral engineering, hydrology, computer modeling, operations research, economics, and allied disciplines. An exhaustive study of the phenomenology of a leach dump or heap requires detailed knowledge of the simultaneous interaction of'

Jan 1, 1972

By G. Atesok, M. Hancer, M. S. Celik, O. F. Emrullahoglu

Multivalent ions are shown to activate the flotation of colemanite in the presence of sodium dodecylsulfate (NaDDS). Floatation recoveries versus barium ion concentrations exhibit three distinct regions of floatability. Adsorption, zeta potential and solubility mesurements under comparable conditions reveal that Region I is characterized by the uptake of Me2+ ions followed by electrostatic attraction of sulfate ions onto the oppositely charged surface. The improvement observed in flotation recoveries in Regions II and III is ascribed to surface and bulk precipitation of metal dodecyl sulfate onto colemanite, respectively. While the most soluble BaDDS ions yield the highest activation, the least soluble MgDDS achieve the lowest activation. It is postulated that metal ions depending on their solubility products with DDS are capable of activating the boron minerals.

Jan 1, 1993

By Kotaro Ohga, Kiyoshi Higuchi

In our laboratory, a new detection system using smell detectors was developed to detect the spontaneous combustion of coal and the combustion of other materials used underground. Laboratory experiments were carried out on several kinds of coals, including South African coals, and machine oil, wood and rubber used in belt conveyers. The following results were obtained: 1) Spontaneous combustion of coal can be detected earlier by smell detectors than by conventional CO detection methods. 2) There were no differences in the results using different kinds of coal. 3) Combustion of other materials can also be detected earlier by this system than by conventional detectors for gas and smoke. 4) Use of this detection system enables one to discern the source of the combustion gases, whether it be coal, wood, oil or rubber.

Jan 1, 1995