Search Documents

A bearing isolator is a noncontact, nonwearing, permanent bearing protection device. It has a rotor and a stator, and the two are unitized, so that they do not separate from one another while in use. The rotor turns with a rotating shaft, while the stator is pressed into a bearing housing. The two components interact to keep contamination out of the bearing enclosure and the lubricant in. Bearing isolators do not require lubrication or any particular shaft finish or condition. The best bearing isolators are made of metal, usually bronze. They use a vapor-blocking feature that inhibits the free transfer of vapor contamination when the rotating equipment is cycled on and off.

Jan 1, 2004

By M. Botz

Anatolia Minerals Development Limited (AMDL) is constructing the Çöpler Gold Project in eastern Turkey and commenced mining in the fourth quarter of 2009 with gold production scheduled to begin in the fourth quarter of 2010. The project is a 15,500 tonnes/day oxide heap leach with three-stage crushing, agglomeration, carbon adsorption and electrowinning for final metal recovery. Leach solution copper levels are expected to be relatively low during the first two years of production but will increase in later years due to higher copper content in the mined and processed ore. Over the mine life approximately 40 million tones of ore will be placed on the leach pad, which will contain about 35,000 tonnes of copper. Metallurgical testing indicates copper extraction will vary by ore type and, if controls are not implemented, may lead to copper levels exceeding 1,000 mg/L in pregnant solution. High copper levels in leach solution have the deleterious effect of increasing cyanide consumption and potentially overwhelming the ability of the carbon circuit to effectively adsorb the principal economic metals, which in this case are gold and silver. Using data obtained from laboratory leach column testwork, the heap leach facility was modeled using METSIM process simulation software to estimate the build-up of copper in leach solution over the mine life. Laboratory testwork was also performed to evaluate process conditions for treating a portion of pregnant leach solution via sulfide addition to precipitate saleable copper as copper sulfide (Cu2S).

Jan 1, 2011

By B. M. Eiter, J. Hrica, D. R. Willmer

"Mineworkers are routinely tasked with making critically important decisions about whether or not a hazard presents an imminent danger. Researchers from the U.S. National Institute for Occupational Safety and Health collected formative data to investigate mine safety professional perspectives on workplace examinations, which revealed a potential gap in how mineworkers are assessing risk. During interviews, participants revealed not having a systematic methodology for mineworkers to use to determine if a hazard is considered imminent danger. In this paper, we identify and describe three distinct categories of imminent danger complexity and discuss potential steps that could lead to improved identification of imminent danger situations. Finally, we identify potential practices to incorporate into risk management efforts, including feedback, communication and specialized training, to increase awareness of imminent danger situations. IntroductionIn recent years, the metal and nonmetal mining sector, as categorized by the U.S. Mine Safety and Health Administration (MSHA), experienced an increase in the number of fatalities occurring at mine sites. From 2013 to 2015, 69 mineworkers were fatally injured, twice the number of fatalities in each of the previous two years (MSHA, 2015a). As a way to address this increase, MSHA issued its P15- IV-01 program policy letter, suggesting that “miners would benefit from rigorous workplace examinations conducted by experienced and trained examiners” (MSHA, 2015b). The goal of these examinations is to find hazards in the field and mitigate them before they cause injury or death to mineworkers. While it is important to identify all hazards in the workplace, it is critically important to identify those hazards that are considered imminent danger because they require an immediate response to avoid a severe or even fatal injury."

Jan 9, 2018

By J. Marsden

Lift height, overall heap height and climate all play an important role in determining precious metals leaching rates, recoveries, operating costs and capital cost requirements for heap leaching operations. The effects of these factors are not easy to predict from testwork, and this can result in unexpected delays in metal production, lower recoveries than expected and higher capital and operating costs than necessary. This paper investigates the economic impact of lift height, overall heap height and climate on heap leaching and provides criteria to assist in the design and operation of leaching facilities. Descriptions of three heap leach operations in the western USA are provided to support the discussions and conclusions.

Jan 1, 1995

By Verya Nasri, Mehdi Bakhshi

The development of the Montreal metro extension Line 5 -Blue Line- toward the northeast are located between the existing Saint-Michel station and Anjou. It consists of 6-km long two-track tunnel, five new stations and six auxiliary structures. Most of the tunnel (5.5 km) will be excavated by a 9.6 m diameter shielded rock TBM and supported by a precast segmental lining system. TBM will be fitted for probing and preexcavation grouting to control water inflow into the tunnel during the excavation. This paper presents major design aspects of the TBM tunnel including alignment, geological condition, spaceproofing, precast segmental lining, and geotechnical instrumentation and monitoring.

Dec 1, 2022

By E. G. Kelly

This paper describes the performance of a modern compound trough profile spiral that is optimized for fine coal cleaning. Reduced performance (Tromp) curves are presented to compare these new spirals with older designs, as well as with other commonly used coal cleaning equipment. As an aid to equipment selection and circuit design, data are also presented to show how variables, such as flow rate, pulp density, and particle size affect efficiency and the separation specific gravity.

Jan 1, 1984

By N. Edmonson

An examination of the statistics of the world phosphate fertilizer industry since 1980 reveals an increasing tendency for fertilizer manufacturing activity to concentrate in phosphate rock mining areas. The economic justification for this resource-oriented strategy is clear. The choice between shipping phosphate rock, a comparatively low-value product, and shipping more valuable finished fertilizers will always be resolved in favor of the latter if cost considerations control the decision. The historical existence of substantial phosphate fertilizer manufacturing capacity oriented toward fertilizer-consuming activities and dependent on imported phosphate rock shows that narrow cost considerations have not always determined the industry's location. One is entitled to ask what conditions have changed to precipitate the observed relocations, and how permanent these changes are. These questions are the subject of this investigation.

Jan 1, 1995

By Natalie White, Joel Asp, Allyz Kramer

"Minnesota has robust reclamation standards and have proven results in the taconite mining industry. Reclamation of overburden spoils, lean ore spoils and fine tailings from taconite production has generally been successful on the Iron Range, using a low input standard reclamation practice. Success at reestablishing vegetation on these landscapes is likely due to fairly favorable chemical and physical properties (e.g., few limitations due to acidic generating materials, metal toxicities and water and nutrient holding capacities). However, coarse tailings reclamation has proven more difficult, presumably due to lower nutrients and challenges with moisture holding capacities. Research efforts conducted since 1990 have struggled to develop a reclamation strategy for coarse tailings that meets the Minnesota Mineland Reclamation Rules, Chapter 6130. However, new breakthroughs in scram mining technologies are producing fine and coarse tailings that have not been encountered nor reclaimed in northern Minnesota. Scram mining in Minnesota is defined as those mining operations that produce natural iron ore concentrates. Innovative research is underway to investigate and determine successful reclamation strategies to reclaim scram mining tailings from these scram mining operations. The research program is conducted through collaboration with SEH, Prairie Restorations, Inc. (PRI) and Mining Resources, LLC with funding support from the Iron Range Resources and Rehabilitation Laurentian Vision Partnership minescapes grant program.The research program was divided into three phases:Phase I. Bench-scale testing to identify successful treatments to reclaim and restore scram tailings through evaluating surface soils amendments, viable seed mixes and plant germination, growth and densities. Phase I was completed in early 2015.Phase II. Field-scale pilot trial to test larger scale effectiveness of the treatments deemed successful in Phase I and test various vegetative assemblages and planting techniques focused on the unique challenges with scram tailing basins. Phase II was completed in late 2016 with a summary monitoring report.Phase III. Produce a technical report of results for the research undertaken in this study, as well as compile prior reclamation results used during previous Minnesota iron mining reclamation projects on tailings basin applications. Phase III was completed in 2017 with a summary monitoring report and recommendations."

Jan 2, 2018

By Phil Pennington, D. Jack Adams

Mining and processing of minerals, metals, and fossil fuels can release selenium and arsenic into wastewaters. Both selenium and arsenic are difficult to remove to levels that meet current drinking water and discharge criteria. These metalloids can be used as electron acceptors by microorganisms transforming them back to reduced states, thus removing or stabilizing them. Bioremediation cost effectiveness will be discussed in terms of site information required, microbial populations, co-contaminants, pH, redox, and nutrients. Full-scale, economical ex situ and in situ biotreatments are possible and can produce 1,000’s of times less sludge than conventional precipitation technologies.

Jan 1, 2005

By J. Winterton

Cripple Creek and Victor Gold Mining Co. is developing a full-scale pad injection program as part of the overall operational plan for the Valley Leach Facility. As part of the development process the mechanics of the injection methodology are evaluated in the context of physical injection measurements, outcome from geophysical monitoring, and gold leaching theory. The results indicate that hydraulic fracturing analogies advanced heretofore do not accurately describe injection phenomena in unconsolidated and noncohesive material typical of leach pads. A new interpretation is presented and extended to define operational strategies for maximizing gold production.

Feb 27, 2013

By N. Arbiter

The theoretical analysis of tumbling mill energetics and performance has largely neglected mill dimensionality, and, in particular, the importance of the length/diameter ratio. This is in spite of the fact that practice varies substantially in this area: geographically, for semi-autogenous and autogenous mills, as between North America and South Africa/Scandinavia; historically, for overflow ball mills, for which the L/D ratio has increased significantly from the earliest small mills to/the largest mills currently. The present study is concerned primarily with the influence of the L/D ratio on the design and operation of overflow ball mills; on the occurrence of the overload phenomenon; and on the limits, if any, it may impose on mill capacities because of critical pulp axial velocity limits. It will be shown that the shape face or is of major importance in this area; and that its adjustment to the extent that this is practical should remove the diameter limitations previously postulated for this mill type.

Jan 1, 1990

By L. A. Bakhvalov

According to the practice of mining management in the system of industrial complexes, the Kazakhstan gold mines are part of the mine processing industrial concerns providing ore-mining and ore-dressing. The cycle technology of winning operations used at the mining of vein deposits in the mines of the industrial concern is mainly provided by the systems of scrapping, scipping and electric locomotion. At present the information and computer system, elaborated on the basis of the Maikain underground mine is intended for creation of the system of automatic operation for the industrial complex mines. The information and computer system includes: - parametres characterising the accepted technology of works; - the main parametres characterising the technical devices of operation and control ; - information about the material, technical and personnel resources available at the mine; - mining and geological conditions of the deposit; - the facilities of the subsidiary units, of the mine; - the direct parametres and technico-economical indices in which the mine efficacy and activity is estimated. The suggested structure of the automatic operation system can be sensibly realized with the application of the microprocessor on the first level, the personal computer IBM PC/XT or PC/AT on the second level. For the complete realization of the project each mine will need 4-5 computers (as PC/XT), one IBM PC/AT and each mine complex - one super IBM for creation of the distributed information bank and its including in the integral world communication system.

Jan 1, 1992

By Theodore H. Budd, Austin M. Cooney

The North Shore 9 Collector System comprised an integral part of the Milwaukee Metropolitan Sewer District's Water Pollution Abatement Program. The project required the construction of 1,490 m of tunnel, ranging from 1.5 m to 4.6 m in diameter along three separate alignments beneath arterial streets traversing Milwaukee's central business and cultural districts. This paper details the various aspects of the tunnel drives which were accomplished using two Lovat EPB type TBMs in conjunction with pipe-jacking procedures. Shaft configurations developed for the project, including ancillary subsidence mitigation components and portal pressurization facilities are discussed. Anomalies in observed soil behavior at variance with the parameters delineated in the project's geotechnical report are addressed.

Jan 1, 1993

By Ashraf A. M. A. Wali

Many of the economic resources of Egypt have been recognized and exploited for thousands of years (e.g. gold and copper). Most of these minerals, particularly those from hard-rock sited deposits, are found in complex form along with other components while those present in sedimentary sequences are largely in simple compounds or as native elements. Recognition of their characteristic settings (structure, basin development, environment of formation etc.) is the main clue in predicting and locating their presence. The main economic minerals exploited in Egypt today come from sedimentary sequences and include sodium and potassium chlorides, gypsum, sulfur, and sedimentary iron ores. Large amounts of low grade sedimentary phosphates are known but are not of economic value at today's prices. Recent intensive investigation in the north-eastern Sinai (EI Arish) and along the southern coasts of the Gulf of Suez has revealed new and extensive sulfur and chloride deposits, and considerable oil and gas are now being exploited from closely related sediments. Tin is the only mineral that is produced from hard-rock sources, and gold and copper deposits are present but not of high enough grade to be economically viable. However, a significant part of Egypt has not yet been studied in enough detail to close the door on future discoveries. Another point of considerable geological interest is the presence of diverse, modern evaporitic settings, from which we may draw the analogs for many of the older gypsum, anhydrite, chloride and sulfur de-posits. In fact these analogs are so well displayed that both the Sinai and Gulf of Suez-Red Sea evaporites (Middle and Upper Miocene) can be readily compared with these modern deposits.

Jan 1, 1990

By R. L. Grayson

Conventional mine safety wisdom states that "the most efficient mines are also the safest." Since the 1980s, small mines (and contractors) have been targeted as the most dangerous ones because of their fatality records. Statistical testing of 1993 West Virginia safety and production data indicated that the most efficient WV mines were not the safest ones, considering correlations between the severity measure and tons per employee-hour, except for very small mines. This paper will present the results of an extended analysis of WV mine safety using 1993 and 1996 data, concluding with the method used to suggest current priorities for focusing interventions.

Jan 1, 1998

By M. Oliverio

The Cigar Lake uranium deposit was discovered in 1981 at the south western end of Waterbury Lake, approximately 660 km north of Saskatoon in the province of Saskatchewan (see Figure 1). It is the largest undeveloped high grade uranium deposit in the world. It contains proven and probable reserves of more than 226 million pounds U3O8 at an average grade of 20.7%. The world average grade is less than 1% U3O8. [ ] The ore body is located about 450 m below surface at the interface between sandstone above and basement rock below (see Figure 2). The sandstone is fractured rock and saturated with water. This makes water inflow a real hazard at the mine. In fact there have already been two significant mine inflow events. The first of these occurred in October 2006 and resulted in the flooding of the mine. The second occurred in August, 2008 during mine recovery activities.

Jan 1, 2011

By M. A. Reyes, L. Yan

Heat and humidity buildup withn refuge alternatives (RAs) may expose occupants to physiological hazards such as heat stress. The Mine Safety and Health Administration (MSHA) regulations require RAs in underground coal mines to provide a lifesustaining environment for miners trapped underground when escape is impossible. RAs are required to sustain life for 96 h while maintaining an apparent temperature (AT) below 95 °F (35 °C). The National Institute for Occupational Safety and Health (NIOSH) tested a 10-person tent-type RA, a 23-person tent-type RA, and a 6-person metal-type RA in its underground coal mine facilities to investigate the thermal environment over a 96-h period. The test results showed that mine air and mine strata temperatures surrounding an RA occupied by simulated miners (SMs) increased over the 96-h test period. The test results suggest that RA manufacturers should consider this increase in temperatures when calculating and evaluating RA components during surface and laboratory tests. The findings can equip stakeholders with additional considerations for calculating the interior heat and humidity temperature profiles for occupied RAs not tested in situ.

By E. C. Westman, F. J. Shreve

This paper presents the design and construction of a multi-channel geophone array that improves tomographic imaging capabilities in both surface and underground mines. Especially important in the design of the array is sensor placement. Three issues related to sensor placement are addressed in this paper: 1) sensor placement in long, horizontal boreholes, 2) development of simple, robust, MSHA-acceptable clamping unit, and 3) orientation of the geophones within the borehole. Improved imaging capabilities will produce energy, environmental, and economic benefits by increasing exploration accuracy and reducing operating costs.

Jan 1, 2002

The OptiPit® software program is developed based on expertise gained at the Colorado School of Mines (CSM) using Mixed Integer Linear Programming (MILP) techniques. This program has been developed to satisfy the need in the mining industry for a multi-time period schedule and cutoff grade optimization tool that handles large scale open pit and underground mining operations involving many dumps, stockpiles, complex processing options and blending requirements. The current software (or earlier development versions) has been beta tested and used on various large scale projects within Placer Dome Inc., Newmont Mining Corporation, and Phelps Dodge Corporation since 2003. Through the use of this software, these companies experienced additional value creation by optimizing mine sequences, cutoff grades, material process flows and stockpiles under complex operational and processing constraints. This paper will present simple case study results to demonstrate the power of OptiPit® when used as a cutoff grade optimization tool. Furthermore, the paper will show, by example, how significant the difference in the Net Present Value (NPV) of a given project can be, depending on whether results are obtained by way of cutoff grade optimization using OptiPit®, or by using traditional breakeven cutoff grade approach.

Jan 1, 2007

By E. Watkins, S. J. Schatzel, V. Gangrade, R. Kimutis, J. Addis, C. Hollerich

The recent shale gas revolution in the United States has led to the drilling of hundreds of unconventional shale gas wells in active and future coal reserves in traditional coal-mining regions of Pennsylvania, West Virginia, and Ohio. This paper summarizes the impact of a shale gas well breach on the mine ventilation system of an operating longwall panel. This study utilizes a 1:30 scaled Longwall Instrumented Aerodynamic Model (LIAM) to simulate a single-panel longwall operation. The LIAM will be utilized to identify flow pathways and distribution patterns of gas from breached gas well scenarios in an operating longwall in the Pittsburgh Coal Seam. Sulfur hexafluoride (SF6) tracer gas is utilized to simulate a breached gas well. Preliminary findings suggest that the breached gas is diluted to regulatory levels and does not accumulate in the mine entries or in the longwall gob when the longwall panel is adequately ventilated. Overall, this study characterizes the potential interaction between shale gas wells and the mine environment in the event of a gas well breach, which provides critical information to the industry and regulatory agencies for improving safety, health, and welfare of miners.

Mar 2, 2022