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In September 2003, a test was conducted to see if a115-mm- (4.5-in.-) diam Mocap Vari-Stem blasthole plug could improve the pattern of explosives using different top stemming material. The test took place at the J.S. Faulkroad and Sonsstone quarry in McCalisterville, PA. The test consisted of a production stone blast. Half of the holes were stemmed with standard crushed stone. Two-thirds of the remaining half were stemmed with Vari-Stem plugs and crushed stone. And the remaining one-third of the second 50 percent was stemmed with Vari-Stem plugs and only drill cuttings.

Jan 1, 2004

By D. Richter

The Pyrometallurgical refining stage of ferronickel manufacturing produces a slag rich in iron and nickel, which is usually further processed for metal recovery. The recovered material is returned to the refining or smelting stages, depending on the amount of impurities. A series of tests was carried out on the Mineração Morro Azul refining slags, aiming at the recovery of the metallic particles through physical processing. Minor changes in the process showed improved results. This paper compares the textures of these slags after being cooled at ambient temperature and granulated under water at high pressure and flow. It concludes that the cooling process is intimately connected to the work index of such slags, thus resulting in direct impact in operating costs.

Jan 1, 2011

By Leping Liu, Sachin Urade, Li-Ting Chen, Pengbo Chu

This study aims to provide industrial perspectives on the current U.S. metal mining engineering education and areas for improvement. An online survey was designed to seek opinions from the U.S. mining industry. Findings indicated a shortage of qualified graduates from the current U.S. metal mining engineering education system. The qualifications that need to be improved include engineering sciences underlying mining methods, mining design experience, mining feasibility study, the connection between theory and practice, and understanding of the overall mining operation. The survey also identified future desired qualifications, such as the ability to acquire and apply new knowledge as needed and sufficient field experience. Respondents recommended enhancing collaborations between industry and academia.

Oct 1, 2023

By M. Karmis, C. Haycocks

The evolution of longwall mining is briefly traced from its inception in England in the 1620's. In the beginning this method recovered 90% of coal with roof closure controlled by packs and walls. Mechanization began with kerf cutting, crude face conveyors, and improved face support. Full face mining was accompanied by the introduction of self- advancing hydraulic supports. U. S. longwalls evolved a retreating system to recover blocks of coal outlined by room and pillar panels. Computer control combined with the most modern technology have greatly increased productivity. Past trends are used to predict future technological directions.

Feb 24, 1997

By C. D. Hebert, M. R. King

The 56,000' (17 km) long San Vicente Aqueduct Pipeline tunnel is being constructed using precast concrete rings to act as preliminary ground support through two sections of the bored tunnel with lengths of 9,450' (2.9 km) and 33,700' (10.27 km).The six segment bolted trapezoidal ring was manufactured using a combination of steel fiber reinforced concrete and self compacting concrete in vertical moulds. This paper briefly describes the design and function of the segments, and reviews the development stages of the concrete mix, and the advantages and disadvantages of the adopted manufacturing method.

Jan 1, 2007

By H. Lowers, B. Van Gosen

The Iron Hill (Powderhorn) carbonatite complex is a 31 km2 alkalic intrusion located about 35 km south-southwest of Gunnison, Colorado. The intrusion has been well studied and described because of its classic petrology and architecture of a carbonatite-alkalic complex. The complex is also noteworthy because it contains enrichments of titanium, rare earth elements, thorium, niobium (columbium), vanadium, and deposits of vermiculite and nepheline syenite. In particular, the complex is thought to host the largest titanium and niobium resources in the United States, although neither has been developed. It may be economic to extract multiple resources from this complex with a well coordinated mine and mill plan.

Jan 1, 2007

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 David Caiden, Geoffrey Fosbrook, Jaidev Sankar, Donald Phillips, Jon Hurt, Anil Parikh

This paper will cover the progress being made on Phase 1 of New York’s Second Avenue Subway line. It will include a description of construction progress on the first contract to be let, which consists of a 248 m (815 ft) long launch box, 3.9 km(2.4 miles) of TBM tunnels and a tunnel sump; the packaging strategy for the remaining work; and the progress through Final Design of the remaining packages, including the two large span rock cavern stations.

Jan 1, 2007

By Richard E. Gertsch

Mechanical mining holds great promise for the mining industry. Realizing this promise depends on developing the tools needed to mechanize a mining operation with a reasonable expectation of success. Mechanical mining entered the 1990s with new machines, new operating methods and new ideas for the future. Mechanical mining can provide higher production, increase safety, reduce roof support requirements, create smoother openings for better ventilation, substitute continuous production for cyclical drill-and-blast procedures, and create opportunities for automatic and teleoperated control. The full promise of this important technology still lies ahead. Obstacles include: • Long-term production prediction: Mechanical systems have a high capital cost. Although recouped by lower operating costs, the tradeoffs are not always clear to mine operators. • Cutting tools for hard rock: Rock of more than 103.4 MPa (15,000 psi) cannot be cut by flexible mining machines. • Machine designs: Many machines cannot convert the required power into rock cutting capability. • Engineering: Better use of the machines in the mine is needed.

Jan 1, 1994

By Mark Ioli, Debra Struhsacker

In September 2004, Gale Norton, U.S. Secretary of the Interior, presented the Manhattan Mine with a U.S. Bureau of Land Management’s 2004 Hardrock Mineral Environmental Award. The Manhattan Mine is a sustainable development showcase. The reclamation accomplishments at this Nevada gold mine demonstrate how modern reclamation techniques can restore an old mining district into an aesthetically pleasing landscape that can support multiple and sustainable uses. In a collaborative effort that relied on substantial community involvement, Round Mountain Gold Corp.(RMGC) has improved the environment and eliminated a number of public hazards associated with old, unsafe mining features. RMGC’s community collaboration, innovative engineering, creative reclamation design and corporate commitment to environmental excellence show what Secretary Norton’s 4 Cs Initiative looks like on the ground and inaction.

Jan 1, 2005

By Marianne Snedeker

In September 1985 we published a questionnaire asking about the content of MINING ENGINEERING and about your interests. By Dec. 10, our cutoff date, we had 430 responses, representing about 1.5% of the 28,238 people who received the September issue of ME. In the data that follow the tabulation and percentages are based on the number of individuals who responded to the particular question. About ME Through responses to the questionnaire, we were hoping to learn more about you, your interests, and how the magazine could better serve you. Those of you who responded told us something positive - you look at or read the magazine. Of the 430 respondents, 428 or 99.5% indicated that they had read or looked through the July and/or August issues. Those of you who refer to the magazine once are 207 or 48.5%. Those of you who refer to the magazine two or three times are 193 or 45.2%. Those of you who refer to the magazine four or more times are 27 or 6.3%. How much time do you spend reading the magazine? Of those responding to this question: 64 spent up to 1/2 hr 15.0% 224 spent up to 1 hr 52.6% 115 spent up to 1-2 hr 27.0% 23 spent more than 2 hr 5.4% In an informal survey among our staff, we determined that most people spend 1/2 to 1 hr reading magazines to which they subscribe at home. Does that match your experience? Many of you, 335 or 79%, clip your magazine for further reference. Also, many of you, 313 or 73.6%, do not pass your copy on to another reader, indicating that you are clipping it or receiving the magazine at home. Those magazines that are passed on reach: 1 person 3 0.7% 2 people 64 15.1% 3-5 people 34 8.0% 5 or more 11 2.6% Answers to what portions of the magazine you find useful indicated that the top three were Industry Newswatch, feature articles and Technical Papers; see Table 1. The "other" category included advertising - display, classified, Employment, and Professional Services - Washington Survey, New Products, Free Literature, book reviews, technology news, and Coming Events and Short Courses. We asked your appraisal of the technical level of the magazine. Of those responding, 39 or 9.1% indicated that it is too technical, 55 or 12.8% indicated it is not technical enough, and 335 or 78.1% judged it to have the correct technical level. In response to the question about whether you like to read an occasional feature that is not technically oriented, 21 or 5.1% said no, but an overwhelming 94.9% (393) said yes. Of the specific

Jan 1, 1986

By D. R. Wilburn

The worldwide budget for non fuel mineral exploration was expected to increase by 27 percent in 2003 from the 2002 budget, according to the Metals Economics Group (MEG) of Halifax, Nova Scotia. The increase comes after five years of declining spending for mineral exploration. For the first time in several years, all regional exploration budget estimates for 2003 as defined by MEG would increase from similar 2002 estimates. However, MEG included 193 more companies in its 2003 survey than in 2002. As with previous MEG survey reports, estimates reflect anticipated expenditures rather than actual dollars spent. Caution, therefore, must be taken when comparing 2002 and2003 estimates or evaluating the magnitude of regional changes from year to year. Sample variations and currency exchange rates may influence year-to-year variations of MEG data. Even so, it is likely that the general climate of improved metal prices in 2003 encouraged companies that had previously left the mineral exploration sector or reduced their exploration activity to once again focus on minerals exploration or increase exploration activity and budgets.

Jan 1, 2004

By Philani Larrance Ngwenyama, Ronald CW Webber-Youngman

The survival chances of trapped miners in underground mines depend on how quickly they can be located and rescued post-accident. During entrapments, emergency rescue is highly desired but can be hindered by the lack of positioning information when a fit-for-purpose missing-person locator system is not available. Various types of missing-person locator systems are available to aid search-and-rescue operations. From the wide range of the available systems, selecting the most suitable one becomes the next challenge. The available systems have not been measured if they are fit-for-purpose or not, and to what situation. This study proposes user requirements that can be used as a guideline to facilitate the system selection process. These user requirements provide a framework for the design and development of a fit-for-purpose missing-person locator system. The user requirements can also be used for evaluating the performances of a particular system, predict its success, and also drive future research toward developing new technology to enhance the capabilities of the current systems.

Apr 1, 2024

By W. David Tyler

Any mining or engineering-construction excavation that extends below the water table must be dewatered. In many situations, the ground is of low permeability or the workings extend only a short distance below the water table. So water removal can be handled easily and economically by using mobile centrifugal pumps. However, there is an increasing number of mines that have a continuous high flow of water into the workings. Controlling this flow can significantly increase the cost of ore production. Successful implementation of any major dewatering scheme will ultimately rely on a clear understanding of the local geology. This understanding is necessary before an interpretation of ground water conditions can be made. It will dictate which dewatering methods are feasible. Once the geology and the ground water system are known, the scope and timing of the dewatering measures can be varied with the mine plan. Ground water modeling can assist in optimizing the dewatering system, though the precise objective of each model should be clearly defined. Production wells must be sited and drilled so that individual well efficiencies are high. Any lost efficiencies will translate into higher operating costs. Each well must be designed for maximum long-term control of the water table, and pumps sized to operate under continually changing heads. Finally, the investment in each production well must be protected during the mining process.

Jan 1, 1991

By Gunter Swoboda, Harald Wagner

Until a few years ago tunnel construction was based exclusively on experience. In recent years, however, numerical models have increasingly become an integrated part of tunnel design [2]. These models permit good evaluation of the tunnel's support behavior even before it is designed. In particular, numerical methods are highly suited for the development of new construction methods. The prerequisite for this is the application of high-performance pre- and postprocessors, permitting the design engineer to come to a quick interpretation of the analysis results. In future, 3D analysis will take on increasing significance, for which reason this paper also deals with this type of models.

Jan 1, 1993

By Ping Zhang, Xu Ma

Perturbations from mining operations significantly affect the stability of rock masses, especially with the increase in mining depths. This study uses the discrete element method (DEM) to investigate shear slip failure along discontinuities in an underground mine, aiming to quantify seismic moment and seismic energy to better understand seismic hazards.

May 1, 2023

By Andrew Kaczmarek

The mining industry is enjoying a much needed and long awaited increase in demand for natural resources. However, consolidations in the mining and mining service industries, along with a generational departure of experienced industry professionals, is challenging today’s mining companies. These challenges are not only in maintaining their existing operations, but also in securing qualified resources for developing new projects. These challenges are compounded for junior mining companies. They oftentimes lack for operating properties to draw experienced professionals from. Also, juniors have to compete with the majors’ “mega-projects” for experienced project personnel from the reduced ranks of engineering companies. This article discusses some strategies developed by Anatolia Minerals Development (Anatolia) in developing its Çöpler gold project in central Turkey.

Jan 1, 2006

By Jim Baumann

Deposited millions of years ago in irregular paleokarstic channels, Jamaica’s extensive bauxite deposits provide good quality ore for alumina production and subsequent aluminum smelting. Bauxite mining operations are critical to the Jamaican economy. It accounts for a large percentage of Jamaica’s export earnings. Bauxite production in Jamaica accounts for about 10% of the world’s output each year. Bauxite deposits in Jamaica lie close to the surface. They can be extracted using standard surface mining techniques. The deposits occur in scattered pockets across the country’s rugged landscape. So it was necessary for two of the country’s major mining and refining operations to implement cost effective methods for the acquisition and management of bauxite reserves and surface ownership distribution rights.

Jan 1, 2002

By Liming Yuan, Isaac Zlochower, RICHARD THOMAS, Thomas H. Dubaniewicz, Teresa Barone

Mining vehicle manufacturers are developing lithium-ion (Li-ion) battery electric vehicles as an alternative to diesel-powered vehicles. In gassy underground mines, explosion-proof enclosures are commonly used to enclose electrical ignition sources to prevent propagation of an internal methane (CH4)-air explosion to a surrounding explosive atmosphere. Li-ion batteries can create pressurized explosions within sealed enclosures due to thermal runaway. Researchers at the U.S. National Institute for Occupational Safety and Health (NIOSH) measured thermal-runaway pressures of lithium iron phosphate (LFP) cells as a function of free space within sealed enclosures and observed an inverse power relationship. A well-confined cell produced 4260 psia (294 bar) of pressure during a thermal runaway, far exceeding minimum pressure containment specifications for conventional explosion-proof enclosures. Results indicate that adding enough free space surrounding LFP cells can reduce thermal-runaway pressures to levels below that expected for CH4-air ignitions. Measured thermal-runaway temperatures were below the minimum autoignition temperature of CH4-air.

By V. Izaxon

Current practice in mining frozen, underground placers is to support the mine openings by leaving remnant pillars, which are kept frozen to maintain their stability. These pillars may be partially extracted depending on mining conditions, but this practice may be risky, and roof falls are common. Instead of allowing the mined-out areas to cave, the extracted entries could be filled with waste material, which would then be frozen, using cold ventilation air. A finite difference model for analyzing the effects of various parameters on the freezing of backfill in underground mines in the Arctic has been developed and tested. The model also accounts for properties unique to a frozen rock mass, including those that change with temperature. Examination of the characteristics of ice-cemented mining waste materials as backfill indicates that with proper engineering control, a backfill system can be designed for use in production mines. The system will allow increased extraction ratio while maintaining the stability of underground openings with minimum heat impact on the surroundings. These simulated results establish the relationships among the strength, the temperature, and the freezing characteristics of a given material. When coupled with site observations these relationships will facilitate the optimal design of ore pillar recovery methods.

Jan 1, 2004