Search Documents

By A. Miller, M. McNinch, R. Jacksha

Each year, hundreds of mine workers are involved in machinery-related accidents. Many of these accidents involve inadequate or improper use of lockout/tagout (LOTO) procedures. To mitigate the occurrence of these accidents, new safety methods are needed to monitor access to hazardous areas around operating machinery, improve documentation/monitoring of maintenance that requires shutdown of the machinery, and prevent unexpected startup or movement during machine maintenance activities. The U.S. National Institute for Occupational Safety and Health (NIOSH) is currently researching the application of Internet of Things (IoT) technologies to provide intelligent machine monitoring as part of a comprehensive LOTO program. This paper introduces NIOSH’s two-phase implementation of an IoT-based intelligent machine monitoring system.

By M. Alley, P. Schroeder, L. Zelazny, S. Nagle

The Old Hickory mineral sands ore body in Virginia (>2000 ha) currently supports a productive rowcrop agriculture. Reclamation experiments were implemented on pilot-scale mining pits from 1995 to 1998. Half of each mining pit was topsoiled (25 cm) while the remaining half was left as either (1) mixed tails/slimes or (2) re-graded subsoil over tails/slimes treated with 112 Mg/ha yardwaste compost. Post-mining productivity was estimated to be reduced by 23%, 3%, 27%, and 20% for each crop (wheat/soybeans/corn/ cotton) in sequence when compared to undisturbed soils. Variability in surface texture and compaction limit restoration of soil productivity.

Jan 1, 2002

Six pioneers of the American mining industry will be inducted into the National Mining Hall of Fame on Saturday, Sept. 13, at the Museum Convention Center in Leadville, CO. The 16th annual Mining Hall of Fame induction banquet will begin with a reception and open house at 5:30p.m., followed by the dinner and program at 7 p.m. The six inductees include James M. Gerstley, the only living member, and George O. Argall, Jr.; John F. “Leadville Johnny” Campion; Charles R. Nailler; Edwin N. Pennebaker and Russell L. Wood.

Jan 1, 2003

By F. Calizaya

The PT Freeport Indonesia‘s Deep Ore Zone(DOZ) copper deposit is located in the province of Irian-Jaya, Indonesia. Currently, a block cave mine is being developed around this deposit. Production is scheduled to start in year 2000 and to ramp up to25,000 tpd by year 2003. The air quantity requirement for this mine is equal to 780 m3/s. To supply this quantity, the mine will require five centrifugal fans (one 450 and four 750 kW fans). This study summarizes the technical aspects related to the installation and commissioning of one of these fans. The fan was installed on the surface in a parallel arrangement with two others. It has a design capacity of 240 m3/s of air at 2.2 kPa of static pressure. The study presents the installation details from the underground shaft excavation and portal development through fan testing and commissioning. It also presents the results of a monitoring system that was installed to determine the fan duties.

Jan 1, 2000

By X. Zhu, R. Du Plessis, J. D. Miller, D. G. Kotylar

Research on the low-potential hydrophobic state of pyrite with potassium amyl xanthate (PAX) as collector, is reported to help explain and understand the fundamental aspects of the N2TEC flotation process, which was originally developed for the improved recovery of gold from refractory auriferous sulfide ores. Typically in the N2TEC process, air is replaced by nitrogen as the flotation gas, and potassium amyl xanthate is used as collector for the reactive auriferous pyrite particles. The first N2TEC flotation process was commissioned at Lone Tree in Nevada in March 1997 and has been in operation ever since. On the basis of electrochemically controlled contact angle measurements, the low-potential, low-pH hydrophobic state of pyrite has been examined as a function of flotation variables such as pH, gas-phase composition, collector concentration and pyrite potential.

Jan 1, 2000

By S. Underwood

The tracer gas method of conducting ventilation surveys is a means of determining air quantity in underground mines with knowledge of the concentration of the tracer in the atmosphere and the flow rate at which the tracer is being released. The technique is useful in inaccessible areas of underground mines and areas where traditional point measurement of velocity is not practical. Sulfur hexafluoride (SF6) is the industry standard tracer(Kennedy 1987) used in underground mines because it is safe, stable, and not naturally occurring in the mine environment. The implementation of a second tracer will increase the versatility of the tracer gas technique allowing for simultaneous releases for the study of interrelated ventilation circuits, and for conducting multiple experiments in less time. This paper will detail the selection of perfluoromethylcyclohexane (PMCH) as a novel tracer with sensitivity, physical properties, and analysis characteristics similar to SF6. Methods for the release of liquid PMCH into underground mines will be recommended, and the vulnerabilities of sample loss due to condensation of vapor PMCH will be explored. Finally, the benefits and implications of using PMCH as a second tracer will be discussed.

Jan 1, 2012

By S. Chander, S. W. Musselman

The molecular structure of hydrophobic and hydrophilic groups in nonionic surfactants has been related to the wetting and dispersion of selected pigments. The nonionic surfactants included in this study are acetylenic diol based surfactants and ethoxylated alkyl phenols. The Langmuir model could be used to fit adsorption data. Further analysis of the data showed that the free energy of adsorption was a function of adsorption density of the surfactants at the interface. The change in free energy with adsorption density could be interpreted by considering a change in the orientation of the adsorbed molecules. Acetylenic diol based surfatants were found to have an area per molecule of 2-3 times that of similarly ethoxylated alkyl phenols. The wetting and dispersion properties of lamp black, a model hydrophobic surface, by these surfactants were investigated by contact angle measurements and particle size analysis. Acetylenic diol based surfactants with ethylene oxide contents between3.5 and 10 moles per molecule and alkyl phenol based surfactants with approximately 9 moles of ethylene oxide per molecule were found to provide superior wetting abilities. Longer ethylene oxide chains were required for superior dispersion capabilities within each family of surfactants. Complete wetting and dispersion was found to occur above the critical micelle concentration of the surfactants.

Jan 1, 2000

By J. A. Mielczarski

An infrared external reflection spectroscopy (ERS) technique has been developed to study the structure of the adsorbed layer of ethyl xanthate formed on copper and natural chalcocite (Cu2S) electrodes. The infrared technique provides information concerning the identity and the orientation of the adsorbed species at monolayer and submonolayer coverages. X-ray photoelectron spectroscopy (XPS) studies have also been conducted to monitor changes at the surface. The results show that the first oxidation peak on the voltammograms for copper and the first and second oxidation peaks on the voltammograms for chalcocite electrodes are not characteristic of a chemisorbed xanthate species, which is contrary to what has been reported by other investigators previously. As evidenced by the XPS spectra, there was an increase in sulfur relative to copper on the copper and chalcocite surfaces over the potential region where these oxidation processes occur. The spectroscopic results (ERS, XPS) indicate that the second and third (on copper) and the third and fourth (on chalcocite) oxidation processes recorded on the voltammograms are due to cuprous ethyl xanthate adsorption. The orientation of the adsorbed molecules of xanthate was observed to change with increasing surface coverage. Therefore, it has been concluded that xanthate can modify the copper and chalcocite surface in two different ways. At lower potentials, xanthate is a source of sulfur for the formation of a sulfur-rich surface. At higher potentials, an adsorption layer of cuprous ethyl xanthate is formed. Contact angle measurements show that both of these processes of xanthate surface modification lead to an increase in the hydrophobicity of the substrates.

Jan 1, 1990

By Eung Ha Cho, Wendi Li

Wet desulfurization of Pittsburgh No. 8 coal and Illinois No. 6 coal were conducted with sodium hypochlorite in the laboratory. Pittsburgh No. 8 coal was leached by hypochlorite at high pHs in one step only. The hypochlorite concentration varied from 0.2 to 0.6 molar; sodium hydroxide concentration, from 0.2 to 0.8 molar; and temperature was at the levels of 80 and 90°C. The desulfurization of Illinois No. 6 coal was conducted in three consecutive steps of pretreatment in concentrated ammonia at room temperature, leaching with hypochlorite at room temperature and hydrolysis in sodium hydroxide solution at 90°C. In the leaching step, hypochlorite concentration varied from 0.2 to 0.8 molar. The desulfurization method of Pittsburgh No. 8 coal was found to reduce mainly pyritic sulfur. More than 70% of pyritic sulfur removal was achieved at the optimum conditions of 0.4 molar hypochlorite, 0.4 molar sodium hydroxide and 90°C. The desulfurization method for Illinois No. 6 coal was capable of reducing significant amounts of organic sulfur. The removal of organic sulfur achieved a 37.8% reduction at the optimum operation of leaching at 0.4 molar hypochlorite and room temperature followed by hydrolysis at 0.3 molar sodium hydroxide and 90°C. The chlorine content in the coal produced by the chlorination during leaching was kept below the threshold value of 0.3% at the optimum conditions of the desulfurization method for each coal.

Jan 1, 2005

By S. Dixon

The Peñasquito deposit in Mexico is one of the largest grassroots precious metal discoveries developed in recent years. Goldcorp Inc. acquired the gold-silver-lead-zinc property with the acquisition of Glamis in 2006. The Peñasquito property is located in the northeast corner of Zacatecas state, Mexico. The elevation of the property averages 1,900 m (6,200 ft) above sea level. It is situated in a wide east-west valley. Minera Peñasquito, S.A. de C.V., wholly owned subsidiary of Goldcorp Inc. has operated twin SABC-flotation lines since June 2010. Each line is capable of processing 50,000 tonne per day using a SABC grinding circuit followed by flotation to produce lead and zinc concentrates. The addition of a Polysius Polycom HPGR 2417 with dual 3,000 kW drives to reduce the crushed pebbles produced by the SAG mills was planned to increase production to 65,000 tonne per day per line. The production has been limited to 100,000 tpd due to operating issues in the grinding circuit. The operating issue has been the amount of pebbles generated by the SAG mills is significantly less than originally planned. This paper describes the planned installation of a crushed augmented feed to maximize utilization of the HPGR capacity. This coupled with full utilization of the SAG and Ball Mill available energies there is the potential to achieve a 50% total capacity increase from the grinding circuit.

Jan 1, 2012

By J. Kretschmann, N. Nguyen

"The Vietnamese economic growth of more than 5% per year leads this country to an enormous demand for raw materials. In the duration of ongoing expansion, the big challenge in the coming decades will be to make this process as sustainable as possible when it comes to economic, environmental and social objectives. Risk management especially in occupational safety and health (OSH) in enterprises is one of the most important tools to achieve this aim. But until now, this has not been taken into priority by Vietnamese coal mining enterprises. Main reasons for this situation can be found in deficient legislative conditions and in non-synchronized risk management systems. In contrast, Germany has implemented an adequate legal system and the German mining industry has gained lots of experiences in risk management, especially in occupational safety and health. This paper seeks to point out specific challenges how to improve occupational safety and health in Vietnam by transferring and applying German methods and standards."

Jan 1, 2011

By R. C. Kellner

Duval Sierrita Corporation, a wholly-owned subsidiary of Duval Corporation, operates an 86,000 STPD copper-molybdenum concentrator near Tucson, Arizona. Shortly after production commenced in February, 1970, it became apparent that the reduction crushing system represented a limitation to reaching the design capacity of 72,000 STPD. The development work performed on the reduction crushers in order to first meet design capacity, and to subsequently increase production to 86,000 STPD is described in this paper. The Sierrita plant is a conventional three stage crushing sys- tem. All crushers were supplied by the Allis-Chalmers Corporation and consist of two 58 x 89 Superior gyratories, four 138b EHD hydrocones, and ten 384 hydrocones. Screening is performed prior to and subsequent to secondary crushing and in closed circuit with the tertiary crushers. Typical throughput rates and equipment sizes are presented in Figure No. 1.

Jan 1, 1975

By H. K. Lin

Cyclic voltammetric and potential step chronoam-perometric techniques were used to study gold dissolution in cyanide solution. Three distinct anodic and one cathodic peaks appear on the voltammogram between -0.50 and 0.80 V vs SCE. The corresponding reactions were proposed to explain the peaks and the passivations. The proposed reactions were in agreement with the effect of pH, cyanide concentration and the rotating speed of the electrode on the magnitude of the peak currents. Cyclic voltammetric tests, with various vertex potentials, were also conducted to examine the proposed reactions. Steady-state currents at various potentials were obtained by potential step chronoamperometric technique and were compared with transient currents obtained by the cyclic voltammetric technique.

Jan 1, 2000

By M. M. Rajkovich

Just prior to the close of the century, the Federal Mine Safety and Health Review Commission issued its long-awaited decision in Berwind Natural Resources, et al v. Secretary of Labor, to usher in the new millennium. The case arose as a result of a mine explosion in Eastern Kentucky resulting in MSHA’s issuance of 225 citations, not only to the contractor, but to four affiliated entities of Berwind Corporation. While an Administrative Law Judge dismissed those citations as to three of the Berwind entities, both MSHA and the remaining Berwind entity appealed the case to the Commission. Although the Commission effectively left intact the Administrative Law Judge’s decision, it announced a new theory of liability that would apparently be applied in the future, namely the Unitary Operator Theory. This presentation will provide an in-depth look into the Berwind decision and explore the means under which MSHA might impose liability for contractor violations upon other entities in the future.

Jan 1, 2001

By C. J. Roos

Ground engaging tools are used to prevent damage to the main components of earth-moving equipment. These tools consist of everything from shovel teeth to replaceable drill bits to dozer wear plates. The costs of these ?consumable? items are increasing with the costs of raw materials. This project developed a tool to be used by Newmont Mining Corporation to predict the consumption of excavator teeth. This paper presents the results of a Montana Tech research project in which an equation was developed to predict excavator teeth consumption based on production rates and rock properties.

Jan 1, 2009

By V. Svalbonas

The process of grinding mill quality assurance brings with it associated truths and myths. When the mill quality assurance process took its first great steps forward in the late 1970s and early 1980s, they were in response to the conditions existing, in our industry, at those times. In the late 1990s, we are faced with different conditions, and problems, and need fresh solutions. Yet the system developed for the early 1980s has produced no new approaches for the late 1990s, becoming instead more hardened and entrenched. This lack of development and actual resistance to research is now costing the industry significant amounts of money in late start-ups and useless scrap loss.

Jan 1, 1999

By E. R. Spencer

National Institute for Occupational Safety and Health (NIOSH) researchers conducted an investigation to quantify sound levels and to determine the amount of sound reduction provided by engineering noise controls installed in a talc processing plant. Baseline sound level and sound intensity measurements were performed at the plant and the measurement locations were recorded for comparison to post-control measurements. Follow-up measurements were then made at the same locations after the initial noise controls were installed. The plant subsequently decided to implement additional noise controls and the researchers returned to conduct measurements for a final analysis of all noise controls. The most significant results showed a sound level reduction in the main mill area from a range of 93-104 dB(A) down to 90-94 dB(A), and a total sound power level reduction of 21 dB(A) for air classifying mill 3.

Jan 1, 2008

By H. Reed

The precious metal mining industry in Nevada handles and generates a certain amount of hazardous materials and waste on a regular basis. These products range from processing material additives to wastes from laboratory testing, heap leaching, and hydrocarbon treatment and disposal. The volume of materials and wastes is dependent upon the amount of ore processed. Handling, treatment and disposal is dependent on the type of material handled and the waste generated. Owing to the health and safety concerns and due to the existing regulations that control handling and disposal of hazardous materials and wastes, the mining industry is obligated to comply with all applicable requirements for proper handling of these products. Plus, in an effort to minimize any impacts from this effort, the industry is continually looking for alternative methods to accomplish these requirements and to also minimize costs. This paper will discuss the general, and in some cases the specific conditions, by which the industry is coping with the issue and efforts to minimize any impacts from handling, treatment and disposal for hazardous materials and wastes. The subject of compliance with the Toxic Release Inventory (TRI) requirements and bio-treatment of wastes and other technologies will be discussed.

Jan 1, 2001

By John L. Kaplin

The underground construction for the Phase I Combined Sewer Overflow(CSO) Project is on an impressive scale by any measure, appearing more so in a midsize city like Providence, RI. The Narragansett Bay Commission recently completed $350 mil-lion in construction to improve the water quality in Narragansett Bay. This project included a number of serious challenges, delays, and disputes. Looking back on this complex project completed within budget, it is hard to consider the work as anything other than a success. Along the way, this outcome did not always appear certain.

By Paul D. Tomlingson

There are huge benefits for mining operations that have a well-defined maintenance program that is understood and followed across the total operation. But for operations lacking a quality maintenance program, there is equal assurance that nearly every major maintenance problem can be traced to this omission. Few problems will be permanently corrected until such a program is implemented. Definition The maintenance program re-quires the interaction of all mine departments. Initially, the production department will request work and the maintenance department will identify work, principally through preventive maintenance inspection and testing efforts. Maintenance will then classify the new work to determine the best way to respond. Maintenance will plan selected major jobs to enable its crews to carry them out more effectively. Maintenance will schedule the planned work with operations. Supervisors will assign all types of work to their crews then, control the work through effective supervision. As work is completed, maintenance will measure the work using an accurate information system. Next, it will assess overall accomplishments against goals such as performance standards or budgets. In addition, the pro-gram would prescribe a means to evaluate every aspect of the operation as it affects maintenance so that necessary improvements or changes can be identified, prioritized and acted on. Such evaluations should be part of a mine-wide continuous improvement effort. A well-defined maintenance program is one of the best investments a mining operation can make to assure its profitability. Educating the total operation on the pro-gram assures long-term dividends from the investment.

Jan 1, 2008