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By Allison

During the 1980’s, laboratories opened throughout the United States to serve the analysis needs of a rapidly growing asbestos abatement industry. The samples analyzed were either collected during the abatement of known asbestos-containing materials or were suspect asbestos-containing construction materials. Many asbestos analysts received minimal training and used analytical protocols that were industry specific. False positives (reporting a sample as containing asbestos when none is present) went unnoticed or had minor repercussions. The mindset of the industry was to err on the conservative side – it would be better to identify a non-asbestos fiber as asbestos than visa versa. With growing public awareness of the health hazards of asbestos, other materials began to be tested for asbestos content. Rock and ores began to be tested for naturally occurring asbestos by these laboratories using the same protocols or an in-house protocol. Analysts were given no additional training and accreditation, in most cases, it was not required. With no consistency in sample collection, testing protocol or expertise in analysis, significant discrepancies in final results can be expected. If we further complicate this scenario with misidentification of naturally occurring look-a-likes for asbestos, expensive false positives are likely. To avoid the repercussions of misidentification of naturally occurring chrysotile asbestos from look-a-like fibers in rock and ores, correct sampling and analysis protocols with more stringent scientific diagnostic criteria are needed.

Jan 1, 2005

By Larissa Koroznikova, Steve Durkin, Patrick Bouwmeester, Michael Tuck

In currently used mining methods, blasting techniques often causes dilution of valuable ore and results in costly processing requirements. In the context of narrow vein mining of thin and highly concentrated orebodies there is a need of a mining method that can reduce dilution in order to remain economically viable. This research project explored the viability of a new mining technology, thermal fragmentation, in narrow vein mining. Thermal fragmentation technology uses a flame jet to produce extreme heat that spalls the surrounding rock to a strategically located drill hole, as an alternative to traditional blasting. This paper creates a net present value (NPV) model of a mining method using thermal fragmentation, as well as for an existing method used for narrow vein mining; comparisons and evaluations were made regarding the feasibility of the new technology. It was found that while overall costs for thermal fragmentation were relatively high, reductions in wages, haulage and processing costs, as well as increased productivity and ore recovery, meant that the new method would improve the financial performance of any operation. These results identify that there is an opportunity to introduce the thermal fragmentation technology to narrow vein mines within Australia, in order to lower costs and increase profit.

By James J. Meadows, Jason D. Pampena, Emanuele G. Cauda, Lauren G. Chubb

Exposure to respirable crystalline silica (RCS) can cause serious and irreparable negative health effects, including silicosis and lung cancer. Workers in coal mines have the potential of being exposed to RCS found in dust generated by various mining processes. The silica content of respirable dust in one single mine can vary substantially over both time and location. The current monitoring approach for RCS relies on the use of traditional air sampling followed by laboratory analysis. Results generated using this approach are generally not available for several days to several weeks after sampling, and this delay prevents timely and effective intervention if needed. An alternate analytical method is needed to reduce the time required to quantify the RCS exposure of mine workers. The National Institute for Occupational Safety and Health (NIOSH) has developed a new method using commercially available portable infrared spectrometers for measuring RCS at the end of the sampling shift. This paper will describe the application of the new field-based RCS analytical process for coal mines, including the use of the new method with the existing Coal Mine Dust Personal Sampler Unit. In a case study conducted by NIOSH with a coal mine operator in West Virginia, field-based RCS analysis was completed at a mine site to evaluate the new technique. The RCS analysis results obtained by the field-based method in this case study showed sufficiently strong correlation with results obtained by the MSHA standard laboratory analysis method to allow the mine operator to use the field-based method for evaluating process improvements.

By V. L. Franzen, Z. J. Hladysz, C. A. Kliche

The Wharf Resources mine, located in the Bald Mountain Mining District approximately 6.4 km (4miles) west of Lead, South Dakota, has operated a surface gold and silver mine and heap leaching processing facility since 1983. Wharf Resources intends to mine and process gold and silver ore from the Wharf Expansion area which is located on the eastern flank of the currently permitted Foley Ridge Mine. The Trojan Pit for the Wharf Expansion area was initially designed with an overall highwall slope angle of 45o. During mine permit presubmission meetings with personnel from the SD Department of Environment and Natural Resources (SD DENR), the question arose as to whether a detailed slope stability analysis of the proposed Trojan Pit highwalls was completed to justify the 45o slope. Wharf’s response was that the highwall design was based, in part, upon studies completed in1987 on the Annie Creek and Foley Ridge Mines; and, in part, upon subsequent slope stability analyses conducted by Wharf mine personnel through 1996. It was suggested by the SD DENR that the stability study be updated to reflect structural geological conditions in the Wharf Expansion area.

Jan 1, 2000

By Bhaskar B. Thapa, Christopher Laughton, Michael P. Bruen

At Fermilab, located in Batavia, Illinois, a 4,000-foot underground complex of tunnels and caverns is being excavated on a decline of six percent, at depths of up to350 ft, below grade. The site geology consists of dolomitic and shale formations overlain by glacial till. Since the start of construction in March 2000, work to date has concentrated on the excavation and support of the Target Hall cavern, which is characterized by a low rock cover and a final lining of shotcrete. Ground vibrations, noise levels, and rock movement were monitored during excavation by drill and blast methods to prevent damage to experimental facilities, impacts on surrounding communities, and to allow evaluation of cavern performance. The cavern design was based on a UDEC numerical analysis that was validated during construction by comparison to encountered conditions and measured cavern movements.

Jan 1, 2001

By J. W. Jamieson, J. Escartin, A. Steinführer

Evidence of hydrothermal activity on two Mid-Atlantic Ridge oceanic core complexes (OCCs), at 13º30’N (the Semyenov 1 through 5 fields) and 13º20’N (the Irinovskoe field) (Fig. 1) were studied using CTD casts, dredges, TV-grabs and SP surveys during previous research cruises to these sites (Cherkashev et al., 2013, McLeod et al., 2009). In late 2013, the Semyenov and Irinovskoe fields were revisited, this time with an autonomous underwater vehicle (AUV) and a remotely-operated vehicle (ROV) during the ODEMAR (Oceanic Detachments at the Mid-Atlantic Ridge) cruise on the French research vessel "Pourqoui Pas ?". Here we present the first visual surveys and direct sampling of these vent sites. High-resolution (~2 m) bathymetry of the 13º30’N and 13º20’N OCCs and their associated vent fields was collected during 4 and 5 AUV dives, respectively, using the GEOMAR AUV "ABYSS" (Fig. 1). These surveys were flown between 70 m and 100 m above the seafloor, typically at a constant height to reduce vehicle movement. The AUV was equipped with Eh, turbidity, and temperature sensors in order to detect active hydrothermal venting. Over twenty ROV dives with the ROV "VICTOR 6000" allowed for the visual exploration of the OCCs and collection of 59 hydrothermal rock samples from the vent fields. As a result of these exploration activities, the first robust estimates of the size of the deposits, and the geologic controls on sulfide accumulation at these sites can be determined.

Sep 1, 2014

By S. Jennings

The Red Dog zinc-lead-silver deposit is located in the DeLong Mountains of the western Brooks Range in northwest Alaska. The region is located 145 km(90 miles) north of the village of Kotzebue (Fig. 1).Red Dog’s current resource base is 143 Mt (157 million st) averaging 16.1% zinc, 4.3% lead and 83g/t (2.4 oz/st) silver. It is contained in four structurally separate deposits— the Hilltop, Main Deposit, Aqqaluk and the newly discovered Paalaaq deposit. Recent exploration for the Aqqaluk and the Paalaaq deposits has contributed to Cominco American’s understanding of the detailed structural geology of the district and its role in the placement of individual ore bodies.

Jan 1, 1999

By J. Drelich, M. Pawlik

An improved experimental procedure to measure contact angle has been consolidated with coal surface preparation involving polishing with abrasive paper, alumina powder, and a cloth, followed by ultrasonic and mechanical cleaning. Specifically, the captive-bubble measuring technique has been compared with the sessile-drop technique and the former has been recommended for the examination of the hydrophobic properties of coal surfaces. Results of the research program, which is currently under way, on the examination of the effect of the nature, amount, size, and distribution of mineral inclusions in coal, on its wettability are briefly reviewed.

Jan 1, 1999

By S. Weiss, E. Espinoza

The El Sauzal gold-silver deposit is a high-sulfidation, epithermal precious-metals deposit hosted by an east-dipping sequence of dacitic and rhyolitic pyroclastic and debris-flow units of probable Oligocene age. Total gold production since startup in late 2004 is approximately 450,000 oz. of gold. Above the sulfide boundary gold is mainly disseminated as small grains interstitial to alunite, kaolinite and quartz. The majority of the ore is found in quartz-alunite-kaolinite altered rock that mantles tabular to irregular silicic cores of vuggy, residual quartz ±kaolinite ±dickite. Grade domains are modelled as subhorizontal to east and southeast-dipping. Higher-grade domains cut across alteration zones and also coincide with transitions from vuggy quartz to quartz-alunite-kaolinite. The highest grades are commonly found marginal to vuggy quartz in transitional, hematite-rich quartz-kaolinite and quartz-alunite-kaolinite rock.

Jan 1, 2007

By Gary Brendel

India produces about 70 Mt/a (77million stpy) of coal ash (fly ash and bottom ash) from burning about 200 Mt/a (220 million stpy) of coal for electric power generation. The average ash content is 35%. In contrast, the United States produces about 70 Mt/a (77 million stpy) of coal ash from burning 800 Mt/a (880million stpy) of coal for power generation. Its average ash content is less than 10%. In 1998, GAI Consultants Inc.(GAI) embarked on a federally funded, multiyear project to assist the government of India in solving its growing coal-ash management problem.

Jan 1, 1999

By M. Martins

This work presents and discusses the influence of the surface tension (gLV) of methanol/water mixtures on the flotation response of apatite versus gangue minerals conditioned with flotation reagents (75 g/t cornstarch and 100 g/t Berol 867) at pH 10.6. Berol 867 is a collector composed of sodium alkyl sarcosinate plus nonionic surfactant. The highest Schulz efficiency of separation (recovery of apatite minus recovery of gangue) was achieved at ?51.0 mN/m. The critical surface tension of wettability (gC) of apatite was found to occur at 34.7 mN/m when determined by means of gamma flotation experiments, and it was 33.9 mN/m when determined by Zisman?s approach.

Jan 1, 2009

By R. E. Chaves

San Martin Mine is an open pit, gold heap leach operation located approximately 70 kilometers from the Honduran capital of Tegucigalpa. Mining operations commenced in 2000 and were completed late in 2007, while heap leaching operations continue. Reclamation was executed concurrently with operations to the extent practical. The area has distinct rainy and dry seasons and closure objectives include: prevention and mitigation of acid rock drainage, sediment and erosion control, and mitigation of visual impacts. Final closure is well underway at San Martin and this paper describes the closure processes conducted to date, problems encountered, and the subsequent lessons learned.

Jan 1, 2009

By Jacek B. Stypulkowski

This paper discusses the challenges faced by the design team of the under-river crossings of electric transmission feeders in New York City, a densely populated urban area. The under-river crossing of a 345 kV feeder was initially designed as Horizontal Directional Drilling (HDD), but was redesigned as a utility tunnel because of site con¬straints on both sides of the river. Multiple studies addressed location, available tech-nologies and costs. Multiple soil investigation phases addressed design aspects of HDD, as well as tunneling. Contractual issues varied from a design build alternative with Geotechnical Data Report (GDR) to design tender approach with GDR & Geotechnical Baseline Report (GBR).

By J. B. Hadaway

The current limit to power transmission for grinding mills through one mill pinion is approximately 7,500kW. Above this power rating either twin pinion arrangements or Gearless drives are required. The SMTP concept was developed to overcome this limitation by using two pinions with a single large drive motor. The SMTP mill drive offers major advantages in capital cost and greatly simplifies plant layouts, while using an innovative adaptation of industry-proven single helical gearing. Through the use of a single motor, provision of variable speed drive is greatly simplified. The SMTP can also be used for significant power upgrades on existing mills.

Jan 1, 2001

By D. Bogunovic

The U.S. coal mining industry consumes a significant amount of energy, primarily diesel fuel and electricity. The continuous global increase in energy demand, high energy prices, and environmental issues related to carbon dioxide emission represent a substantial challenge for the mining industry. This paper presents a result of research work on development of an integrated data environment system for analysis and control of energy consumption in a surface coal mine. A case study on an operating surface coal mine is carried out to demonstrate the practical application of the developed system. The research work presented here may be used by mining professionals to help provide the answers to the crucial questions of when, where, and how much energy is being used. This developed system represents a framework for efficient management of energy consumption. Key words: surface mining, coal, energy consumption, Information System.

Jan 1, 2009

By M. S. Klima, P. T. Luckie

Proper analysis of washabiity data can lead to the development of a maximum yield coal preparation plant flow sheet. Simulations, as simple as spreadsheet mass and water balancing, are important in examining yield maximization and middlings liberation. Key to such attribute tracking flow sheet simulations is the distribution model, expressing the probability of a species reporting to the product stream. There are many such models in the literature. This paper examines a functional form that can represent or fit most of the proposed distribution functions.

Feb 24, 1997

Atlas Copco Wagner launched its ST1010 Scooptram load haul dumper. The ST1010 replaces the company’s Wagner ST-1000 Scooptram. The improvements to the Wagner ST1010 include increased reliability, ease of maintenance and driver comfort or ergonomics. The ST1010 has been redesigned and has added several new features and options not offered in the earlier model. These include anew boom design with side stops. Heavy reinforcements to the bogie offer better protection against the harsh working conditions in underground mining and tunneling. An auto lube system has also been added as has paint-on grip tread to reduce slips and falls during maintenance checks or repair work. Other features include a heavy-duty, auxiliary-fan motor, an isolated transverter, remote diagnostic pressure taps, a bolt-on battery box, raised air-intake, improved fuel-filter access for easier maintenance, larger wear-bars around the engine tub, and smaller, higher output batteries

Jan 1, 2000

By T. Robyn

The Bolivar Cu-Zn skarn deposit in the Piedras Verdes mining district of Chihuahua is one of many base and precious metal deposits in the north-northwest trending Sierra Madre Belt extending across the states of Chihuahua, Durango and Sonora in northwestern Mexico. The information presented here is drawn from two papers on the Bolivar property1,4 plus new information. Historical mining and exploration for polymetallic Cu-Zn-Pb-Ag-Au deposits in the Sierra Madre Belt dates to Spanish Colonial days. Access to the Bolivar Property (Figure 1) is by paved road (approximately 305 km southwest from Chihuahua) and approximately 80 km by all-season gravel roads to the villages of Cieneguita (population ~1,000) and Piedras Verdes (population ~500) adjacent to the property. [ ] The Bolivar property comprises an old Cu-Zn producer (the Bolivar Mine), exploration concessions adjacent to the Bolivar Mine, and a new camp at the mine that supports mining, exploration and maintenance. From 1980 to 2000, former operators extracted approximately 300,000 tonnes of ore that was hand sorted to an average grade of 5-6% Cu and 25-30% Zn. From 2005-2010, Dia Bras produced from the mine just over 600,000 tonnes at an average grade of 1.7% Cu and 8.6% Zn. Dia Bras transported mineralized rock 275 km by truck and rail to its Malpaso mill, located about 30 km west of Cuauhtémoc in central Chihuahua, from 2005 until October 2011 when the new Piedras Verde mill was commissioned only 5 km from the mine. (Note: the Company cannot use the term ?ore? because it has never completed a feasibility study.)

Jan 1, 2012

By Gregory R. Gorrell

The legal issues surrounding the regulation of subsidence are among the major concerns facing the underground mining industry today. Whether subsidence occurs almost immediately as a result of longwall mining or without warning as a result of room and pillar mining conducted years ago, the resulting disputes are highly controversial and typical of the disputes involving the competing interests of surface and mineral estate owners. Until recently, the law governing these disputes was firmly established under the common law. The passage of the Surface Mining Control and Reclamation Act 1, the utilization of new mining technologies, and the general heightened environmental awareness of our times, however, have interjected new issues into this area of the law. State and Federal court decisions and administrative agency interpretations have helped clarify some of the issues. However, as evidenced by the many recent lawsuits between operators, surface owners, and regulatory agencies, many uncertainties still exist.

Jan 1, 1986

By Michael Day, Paul Kos, Scott Brinton

A hydrogeologic characterization and impact analysis was performed for a proposed quarry at the Hitch Rack Ranch located in the Little Turkey Creek watershed southwest of Colorado Springs, Colorado. Continuous multiple channel tubing, nested piezometers, stream flow measurements, and mapping of known seeps were used to define the three-dimensional potentiometric distribution and areas of groundwater recharge and discharge. Water balance considerations, mass balance calculations, and potentiometric response to earth tides and barometric fluctuations confirmed that the granite fracture system in the ridge area of the proposed quarry has an extremely low bulk hydraulic conductivity resulting in minimal groundwater discharge to sustain the baseflow of Little Turkey Creek. The Little Turkey Creek valley forms the major conduit for groundwater flow exiting from the upper part of watershed underlain by granite. This conclusion has significant implications with respect to mine planning to minimize projected impacts to the hydrologic system and preserve this recharge component to downgradient Denver Basin sedimentary deposits.