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By Dai Wang

Stoppings are necessary ventilation control devices for effective air distribution underground. However, one of the major problems underground mining has is that every stopping is a potential leaking source. Since air always flows from a point of high pressure to one of lower pressure, and the total pressure at every point in intake airways is higher than that in the return airways, air will always tend to leak from intake to return (Tien, 1996). In many mines, less than half of the air entering the mine actually gets to the working areas; the rest of it simply short-circuits directly to return airways through leaky stoppings instead (Timko and Thimons, 1983). Leakage through a stopping occurs because of pressure drops across the stopping and available leaky path in stoppings. Empirical equation has been widely used to characterize the relation the amount of leakage and variables that affect leakage. However the use of this equation requires accurate information for constants which are not always readily available. It is the attempt of this paper to derive an equation similar to the Atkinson Equation that can readily be applied to characterize pressure-leakage relationship for any given stopping.

Jan 1, 1998

Laboratory tests were conducted in a full-scale continuous miner test gallery to evaluate resulting dust levels for changes in face airflow, spray water quantity and pressure, and mining height. The minimum and maximum values tested for each parameter were as follows: airflows between 1.42 and 6.14 m3/sec, water flows between 56.8 and 132.5 lpm, nozzles pressures between 413 and 1379 kPa, and mining heights between 1.52 and 2.74 m. Each of these parameters were evaluated for four common spray system designs. Respirable dust samples were collected in the operator's cab on the miner and in the immediate return. Second-order polynomial models were used to represent expected dust levels and multiple stepwise regression was used to identify significant control parameters for inclusion in the models. Separate models were developed for dust levels at the operator and return locations and for each individual spray system. Interaction between control parameters and curvature effects were found in most models. The analysis indicated that at the operator location, airflow and mining height had the most significant impact on respirable dust levels. In the return, airflow and water pressure were typically the most significant parameters. The models developed for each spray system design can be used by mine operators to guide application of control parameters for a variety of operating conditions and mining heights.

Jan 1, 1994

By William H. Dresher

A recent report to President Reagan from the Business-Higher Education Forum, entitled, "America's Competitive Challenge: Need for a National Response," (1) observes that in the recent past, ". . . much of that research, which is necessary for major breakthroughs and sustained productivity improvements, was redirected to short-term objectives ... At the same time, American universities, which conduct more than half of the nation's basic research, have suffered from an accumulated under-investment in facilities and equipment amounting to an estimated $1-4 billion." Also contributing to the decline in America's productivity, the report said, are "...weak technology transfers between government and industry and between universities and industry..." This report as well as other recent reports and articles have, reopened a subject which has long been debated but rarely resolved-- the interaction between the academic community and industry in the sponsorship and conduct of research. The subject is unfortunately, too often treated as a controversial issue involving ethics and the profit motive when, in fact, the two branches of society -- industry and academia -- are necessarily part of the same system. I would like to speak to you today on the subject of university-industry interactions and to some extent discuss the role of government in such interactions. Finally, I will make some remarks as to how this subject applies to the mining industry.

Jan 1, 1984

By William J. Miles

For compliance with the Hazard Communication Standard and other federal and state regulations, numerous minerals, chemicals and products need to be evaluated for crystalline silica content at a threshold of 0.1 %. The polymorphs of crystalline silica that can occur in chemical and mineral products are quartz, cristobalite and tridymite. Other natural, industrial and synthetic amorphous silicas and hydrates must be distinguished from these polymorphs to prevent over-regulation in the workplace and environment. A number of industrial silica products are composed of glasses, expanded perlite, diatomite, slags, and precipitated and fumed silica products. Amorphous silica hydrates used for industrial products, include opal (hydrated silica of biogenic or inorganic origin), perlite, pumice and tuffs. In addition, crystalline and amorphous silicate minerals and chemicals, abundant in nature and industrial products, must be distinguished from the polymorphs of crystalline silica.

Jan 1, 1997

By M. E. Kuchta

LKAB's Kiruna mine, located above the Arctic Circle in northern Sweden, is one of the world's largest underground mines, and it is one of the most modern. The Kiruna orebody is a high-grade magnetite containing about 80% low-phosphorous iron ore and about 20% high-phosphorous iron ore in situ. The mining method used is large-scale sublevel caving. Due to the blending of high-phosphorous ore with low-phosphorous ore during the extraction process, only about 20% of the run-of-mine ore can be used for the mine's low-phosphorous product. The blending process is highly irregular and difficult for the mine-planning personnel to predict. An algorithm was developed that uses principles of gravity flow to predict the run-of-mine phosphorous grades from the in situ geologic block model. The model can be used for both long- and short-term predictions.

Jan 1, 2003

By LaPoint D. J.

Copper deposits in sandstones are excellent targets for open pit mines using SX-EW extraction and processing methods. The mineralogy consists of chalcocite as the primary sulfide and copper carbonates and sulfates in the zone of oxidation. Two general deposit types are recognized: early diagenetic copper deposits that are associated with the reddening of the surrounding sediments, and epigenetic deposits that are associated with the migration of copper-rich basinal fluids along faults into permeable reservoir beds with a source of reductant. Epigenetic copper deposits are more likely to contain enough tonnage to be economic.

Jan 1, 1996

Controlled blasting experiments in small development drifts were conducted at CANMET's Experimental Mine, from August 1992 to November 1993. The objective of these experiments was to develop suitable controlled blasting techniques for small development headings drilled by jackleg with 32 mm diameter holes. The experimentation also aimed to provide insight into blast damage mechanisms. Particular attention was given to the physical-mechanical properties of the rock and the rockmass structural data in order to make the results applicable to other geological environments. The drift faces were approximately 2.4 m by 2.4 m with 36 to 43 holes drilled to a depth of 2.4 m. Cartridged water gels, emulsions and semigelatin dynamite were used in the cuts and as primers, ANFO as the main explosive and decoupled 19 mm diameter semigelatin dynamite charges were used in the perimeter holes. Smooth blasting techniques and pre-splitting were tested in the underground mine. All the blasts were monitored with a multi-channel blast vibration monitor to which was attached sets of high frequency geophones and accelerometers. This first set of experiments has illustrated the efficiency of con-trolled blasting techniques to reduce blast damage and demonstrated the need for further research to improve the safe and efficient use of explosives.

Jan 1, 1995

By Yoichi Shimada, Katsuyuki Nishida, Shinichi Takahashi, Yasushi Okada, Yohei Nakamichi, Kazunori Oshiro, Taichi Terui, Sigehiko Sugie

"Temporary retaining walls are ordinarily used for tunnel construction work conducted using the opencut construction method. Retaining walls in such instances are typically installed vertically. However, shoring (such as struts and king posts) is required to ensure the stability of retaining walls in cases of excavation work to depths that exceed approximately 4 m. A new design and construction method that focuses on the effectiveness of retaining walls that are installed on an incline was studied with the aim of improving construction workability by omitting shoring. The inclined braceless excavation support (IBES) method, which was developed for use with the inclined buttress method, requires no shoring, even for deep-open-cut construction work and can be applied to deep excavation work on ground with a high groundwater level. This method has been applied at six work sites in Japan in recent years. This paper introduces the IBES design and construction method and presents verification results based on the design method, a model experiment, finite element analysis, and measurements obtained during construction work.INTRODUCTIONBackgroundIn the past, temporary retaining walls used in open-cut construction work have been installed vertically, and shoring (such as struts and king posts) has typically been used to ensure the stability of these retaining walls when the excavation depth reached 3–4 m. However, shoring interferes with structures built within excavations and requires box-outs and penetration sections in the structures, as well as concrete joints that raise concerns about their impact on the watertightness and long-term durability of structures (Figure 1).Shoring also narrows the space available for conducting construction work and reduces construction work efficiency, and the installation and removal of shoring increases the construction duration and cost. As a result, there has been a demand for ways to reduce or eliminate shoring to improve the quality of structures and construction work efficiency."

Jan 1, 2016

By J. S. Chung

As part of ongoing deep-ocean mining research, hydraulic transport systems as well as status of deep-ocean mining systems are reviewed in the aspects of manganese nodules and crusts from 800-6,000-m depth. The emphasis of the investigation of hydraulic transport is placed on the shape effect of particles on the pressure gradients and flowrates. Series of tests are being conducted to study the lift characteristics of a 2-phase vertically upward hydraulic transport of 2 types of small solid particles in a PVC pipe of 1-in (2.54 cm) diameter: irregular-shaped silica sands and equivalent spherical glass beads. Pressure drops and mass as well as volumetric flow rates were measured by electromagnetic (EM) flowmeter and mass flowmeter. The particle sizes used are 8-10 mesh. The results in turbulent flow range of 104 < Re < 105 show that pressure gradients or friction factors are smaller for the spherical beads than the sands. The larger the concentration of the particles are, the larger the pressure gradients become. The larger the particle concentration is, the less the effect of particle shape on pressure gradients becomes. The shape effect is greater for the minimum particle transport velocities than for the settling velocities.

Jan 1, 1999

By G. Bonifazi

Certain deposits of incoherent materials which are near the surface and exploitable by open-pit mining may be characterized in real time before they are mined through an analysis of ground-surface imagery. If the slice to be stripped is not overly thick, in fact, surface texture and color properties may be extrapolated to its entire thickness. Image analysis techniques to process ground surface images acquired in situ (or in the laboratory shortly after their acquisition) which yield pattern vectors representative of RGB color component distributions and HSB texture parameters have been developed. The techniques were applied to a mineral sandy ore deposit containing three different lithotypes. Geostatistical analyses showed that the data used to characterize the lithotypes were reliable. The correct recognition of the lithotypes was carried out using a multi-barycenter classification algorithm. Such in situ image-analysis procedures open the way to the proper selection of the ore to be mined, or the proper way for run of mine (r.o.m). processing, or the appropriate blend to be processed before or at the same time as the mining process itself is enacted.

Jan 1, 1999

By J. M. Bray, R. R. H. Cohen, P. Kiousis, S. R. Al-Abed

"INTRODUCTION Conventional tailing storage and management practices typically utilize engineered facilities, such as ring dikes and valley impoundments. To reduce the environmental costs associated with disposing of mine wastes in tailing storage facilities (TSFs), several beneficial re-use strategies have been developed over the years. For example, thickened tailings have been used for paste backfill. It is common for tails to comprise up to 60% of the material’s total weight and it has been estimated that TSF volumes can be reduced by 60% when using this strategy, (Benzaazoua, et al. 2004). Other beneficial re-use strategies have produced unpaved temporary access roads, hot and cold asphalt, chip seals, self-compacting concrete, and golf course sand traps. This project sampled mine tailings from two different TSFs in Colorado and produced structural concrete that could potentially be used for commercial foundations, sidewalks, and paved roads. The tailings were substituted for the fine aggregates typically found in conventional concrete. The two main objectives of this study were to investigate the structural integrity of the produced concrete samples and the leaching of heavy metals from the resulting concrete. The ratio of tailings to fine aggregate (T/FA) was carefully studied to find if there was a correlation between the substitution rate and the structural integrity. The potential maximum substitution rate was also investigated for the produced concrete specimens. The potential of leaching mining impacted water (MIW) was evaluated by comparing the leachability of the raw mine tailings to the encapsulated tailings by using standard shake extraction prediction tests. MATERIAL AND METHODS Materials The four components that make up the concrete mix design for this project are: cement, coarse aggregate (gravel), fine aggregate (sand and mine tailings), and water. The type I/II ordinary Portland cement (OPC), gravel, and sand came from local cement and concrete companies in Denver, Colorado. Mine tailings were collected from two different TSFs in the Rocky Mountain Region, where Pride of the West TSF in Silverton, CO will be denoted as Site A. The primary metals of interest at the mill site are gold, silver, lead, copper, and zinc. The location of Site B will not be mentioned in this report due to confidentiality agreements with the mining company"

Jan 1, 2016

By F. W. Jessen

The production of salt through brining operations and the recovery of potash salts by means of solution with water constitute, in large measure, processes which have been used for many years. And although the salt industry has utilized dissolution techniques for years and years it has been only recently that a better understanding of the mechanism of solution has emerged. Greater adaptability of solution mining processes for recovery of valuable salts from ore bodies found at greater and greater depth has resulted in increased adoption of such methods. Because of the high costs of mining in beds of limited thickness, modifications probable when extracting mixed halites, and restrictions (mostly self-imposed) regarding the extent of cavern development to minimize or eliminate subsidence more information is needed on the solution mechanism. It is the purpose of this paper to present the fundamental aspects of the problem of total solution of salts and to point out the developments of certain solution mining techniques.

Jan 1, 1971

By Lana Alagha, Ashraf Alsafasfeh, Amal Al‑Hanaktah

As freshwater resources are becoming scarce, the use of seawater as replacement of fresh water is appealing in order to make mineral processing operations more sustainable. Since froth stability plays a critical role in determining the performance of flotation operations, there is an urgent need to study the effect of frother dosage and seawater on froth stability. In this study, flotation tests in seawater were conducted to examine the effect of frother’s dosage (MIBC) on the froth stability and flotation performance of low-grade phosphate ore. The stability of the froth layer was assessed by measuring the froth growth velocity and the froth maximum height at equilibrium. Results indicated that the best flotation performance was obtained at 75 g/ton of MIBC where ~ 90% of phosphate minerals were recovered. At this recovery value, the concentrate grade was determined to be ~ 70%. Results from froth stability experiments showed that the stability of the froth layer increased by increasing MIBC dosage. At MIBC dosage of 75g/ton, the calculated values of dynamic froth stability and the froth height were ~ 0.4 cm/sec and 16 cm, respectively.

Jan 17, 2024

By J. A. Barrera-Godinez

Traditional batch flotation tests produce a limited number of data points from which to evaluate the kinetics of the process. In this research, continuous weighing of froth, from a modified circular flotation cell, using a computer/data acquisition system., has been coupled with chemical analyses from intermittent froth sampling. This combination has permitted the experimental data to be smoothed such that the flotation kinetic parameters could be determined with enhanced confidence. To demonstrate the procedure, a galena ore was floated to permit flotation kinetics to be investigated as a function of cell parameters. It was shown that the kinetic data of this lead flotation most closely correlated with the Huber-Panu three parameter model. In addition the results illustrated the effect of froth thickness, froth scraper rate and air flow rate on the cell performance, in terms of mass flow, grade and recovery.

Jan 1, 1990

By P. M. Hawley

Kennecott Corporation, in joint venture with Galactic Resources Ltd., recently began operation of an open pit gold mining and milling facility near Columbia, South Carolina. The deposit consists of two ore bodies (North and South deposits) hosted in deformed and altered meta-volcanics and meta-sediments of the Carolina Slate Belt. This paper describes the rock mechanics and engineering geology investigations conducted for design of interim, ultimate and final reclamation slopes for the South Pit. Emphasis includes the successful use of drill core orientation techniques to confirm complex geologic structure at depth; the development of a three-dimensional rock mass competency model, incorporating surface mapping data, results of bench mapping documentation, field index testing and laboratory testing; and kinematic assessments for design of optimum slopes.

Jan 1, 1991

By W. M. Cross

The use of fillers and reinforcements for plastics has increased considerably over the past few decades. For example, in the 1980&apos;s the average growth rate of filler use was 5.8%. [Katz and Milewski, 1987] Similar filler use growth rates occurred in the 1970&apos;s due largely to the increase in price of petrochemical starting materials for plastics. While filler use is still sometimes predicated on the cost benefits associated with their addition to the plastic, other mechanical and performance advantages associated with filler addition are being realized, and account for most of the increased usage. Plastic filler types are many and varied, and include both inorganic minerals/metals and organic compounds, with the former type being, by far, the more common. Common mineral fillers include oxides, including both natural and synthetic silica; carbonates, particularly calcium carbonate; clays such as kaolin; and silicates like mica and talc. It has been recognized that a number of factors influence filler performance, including particle size, shape, surface area, and hardness to name a few. In addition, the interaction between the filler and the plastic is of paramount importance as this interaction will determine the wettability, bonding and the adhesion between the two materials, and ultimately, the mechanical properties of the composite. Froth flotation has long been recognized as a viable process to separate different mineral types. [Leja, 1982] Prior to flotation the minerals are liberated from the ore by comminution. The mineral particle size range produced by this comminution process is typically between 300 and 10 microns. This size range is also typical of mineral fillers for plastics. The size similarity between mineral fillers and minerals concentrated by froth flotation is only one of many similarities that can be found.

Jan 1, 1997

By T. J. Lutz, J. L. Carr, J. A. Yonkey, C. C. Jobes

"Since 1984, the date of the first recorded fatality involving a remote controlled continuous mining machine, 38 miners in the United States have been killed when they were struck by a continuous mining machine. Proximity detection is a valuable tool for preventing fatalities, and the use of these systems is expected to significantly improve safety. Proximity detection provides a means to prevent accidents like these. Researchers at the National Institute for Occupational Safety and Health (NIOSH) conducted a series of underground tests to evaluate the accuracy and repeatability of proximity detection systems under a number of conditions such as varying the orientation and height of the personal wearable device (PWD), moving the PWD close to the trailing cable, and activating the machine’s mining mode. At the 2014 SME Annual Meeting, results from tests on first-generation proximity detection systems were presented. This paper will provide results from the similar tests performed with second-generation systems. The results show that performance has improved. For example, the negative impact of PWD orientation and the trailing cable has been reduced. However, some inconsistencies remain. Notably, performance changes dramatically when mining mode is activated. INTRODUCTION Since 1984 there have been 38 fatalities involving striking and pinning of the operator and other workers by the continuous mining machine (CMM) [1]. In August 2011, the Mine Safety and Health Administration (MSHA) published a proposed regulation that would require proximity detection systems on all continuous mining machines except full-face machines [2]. Proximity detection systems are designed to stop machine motion to protect miners from striking/pinning hazards. Several MSHA-approved proximity detection systems are commercially available. MSHA estimates that of the 38 fatal striking and pinning accidents that have occurred since 1984 involving CMMs, the use of proximity detection could have been a preventative factor in at least 28 cases [1]. Furthermore, MSHA estimates that proximity detection could prevent 20% of all deaths throughout the industry [3]. NIOSH researchers have been involved in the development and testing of proximity detection technology since creating the HASARD system [4] and have recently conducted research intended to develop more advanced proximity detection technology for CMMs [5,6,7,8]. In addition, NIOSH has also conducted research investigating how the signals of a proximity detection system propagate [9,10] and have developed a novel method for determining the location of a personal wearable device (PWD) relative to the magnetic field generators [11,12]."

Jan 1, 2015

By G. A. Calboreanu

The deterioration rate of any metal or alloy is increased in a erosion-corrosion application because the passivated surface layer is removed by the solid particles contained in the pumping fluid and the material surface becomes corrosion active again. Numerous attempts were made to engineer a stainless steel with higher hardness and unaffected corrosion performance. Alloys of special interest in such an area are the duplex stainless steels particularly the CD4MCu material which has the capability of being hardened due to its ferrite-austenite microstructure. Unfortunately, the CD4MCu with higher hardness comprises different intermetallic compounds which will increase the corrosion rate. The paper is analyzing the erosion-corrosion performance of a new type CD4MCu with 32% higher hardness and superior wear performance. The corrosion performance of this new alloy is better than the corrosion performance of the common CD4MCu material which the industry could supply. The corrosion effectiveness was evaluated with the Huey test, the potentio-dynamic anodic polarization test and the weight loss test whereas the erosion resistance was established with a low stress ball-on-disk type apparatus. The Wilfley hard CD4MCu material had 39% lower weight loss and 32% smaller volume loss than the common CD4MCu alloy The hardness range of the centrifugal pump parts poured and processed with the Wilfley hard CD4MCu is 320-350 HBN versus 250-255 HBN hardness of the common CD4MCu. After approximately 18 months of experimentation and field testing it was clearly established that the life time of the Wilfley hard CD4MCu is higher than the common CD4MCu and consequently centrifugal pumps were supplied to different customers in North and South America. India and more recently Australia. Sincere thanks to all the A.R. Wlifley & Sons Inc. and Western Foundries Inc. employees who supported and help to implement this work. special thanks to George Wilfley. Dave Cobb. Bill Becker Sr. and Wayne Taylor

Jan 1, 1997

By C. J. Bise, P. Bucks

Central Appalachian coal reserves are a valuable natural resource in high demand, both domestically and internationally, justifying efforts to increase percentage recovery through pillaring. Unfortunately, the challenge associated with pillar extraction introduces additional safety risks during the activity. Although pillaring developed prior to mechanized mining, current technology and mining practices have made this form of mining highly modernized. However, current fatality trends suggest that work still needs to be done to control the residual risk that is not controlled by modern practices, such as those having a personnel-performance-based component. This paper investigates the application of modern coal pillaring techniques and will present a risk-management-based strategy that targets personnel-performance-based risk, in order to improve the ability of safety engineers, managers and trainers to provide training programs addressing the needs of pillaring sections.

Jan 1, 2012

By B. J. Arnold

Coal blending inherently means homogenizing a mixture of coals so that, overall, the properties of the blend meet some specifications for maintaining power plant performance and emission requirements. In common practice, however, coal blending is at best coal mixing. If necessary, more sophisticated blending systems can produce a more homogeneous feed by using accurate weighing devices and on-line coal analyzers coupled with sampling systems. Blending can be accomplished at the mine, on stockpiles, and from bins, bunkers, and silos.

Jan 1, 1994