Search Documents

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 L. Clark

Despite near-record commodity prices, the mining industry continues to search for ways to maintain profits in these times of steadily increasing energy prices and steadily decreasing grades. The pressure is still on today’s miners to continuously improve their operations because they know that one day prices too will drop. Some, however, have seized the opportunity to employ systematic methods to reduce costs and increase the efficiency of their workforce and equipment. As a result, closer attention is being paid to scheduling and the value that could be added by defining the extraction sequence that maximizes the net present value [NPV] of a project. This paper will discuss the challenges faced by Newmont Mining Corporation [Newmont] at its operations and the application of sophisticated software tools and methods in its search of solutions to this problem.

Jan 1, 2007

By T. Johnson

Mining activity in a number of metal ores has been running quite high over the last few years. In particular, those metals that employ acid functional extraction processes such as copper, nickel, cobalt and uranium have been particularly active. The world?s largest nickel mine ? the massive $4.76 billion Ambatovy nickel mine on the African island nation of Madagascar is nearing completion. When it reaches its full production capacity in 2013, the mine will produce 60,000 MT/yr of nickel and 5600 MT/yr of cobalt. Coming on the heels of the Ambatovy project is the Long Harbour Processing Plant in Newfoundland, Canada which will process the ore from Vale?s Voisey Bay mine in Labrador. Voisey?s Bay is expected to generate more than 50,000 MT/yr of nickel ore when it starts up in 2013. Next up will be the Boleo project in Mexico on the Baja peninsula. When commissioned in 2013, the $1.4 Billion Boleo project is expected to produce 60,000 MT/yr copper, 3100 MT/yr cobalt, 36,000 MT/yr zinc and 100,000 ? 250,000 MT/yr manganese carbonate.

Feb 27, 2013

By M. Schafer

The 20 foot diameter cast-in-place tunnel lining for Phase 3 of the Mill Creek Tunnel (MCT-3) has been completed. This paper will summarize aspects of liner design and address the construction approach in placing the liner in areas of tunnel that experienced crown overbreak. Tunnel lining production rates, installation procedures and form buoyancies experienced during concrete placement will also be presented.

Jan 1, 2008

By John Reilly

Costs of complex/underground projects have been consistently underestimated and delivery on time and on budget has been problematic. This has been attributed, to inadequate cost estimates and unidentified and/or insufficiently managed risk. Use of probabilistic cost estimates like the Washington State Department of Transportation?s CEVP® process (developed by the author and others) has produced more realistic cost estimates, explicitly identified and quantified risk (as input to risk management plans) and early awareness of key project issues. This paper updates previous work (NAT 2004), adds implementation detail for probalistic cost estimating as used by WSDOT, FHWA and other agencies and will address key issues in risk management, as related to probalistic cost estimates.

Jan 1, 2008

Electrostatically charged water droplets efficiently suppress breathable dust produced during open air rock crushing operations, according to recently completed independent tests conducted for the Environmental Protection Agency. Since a primary rock crusher produces very heavy clouds of dust, this application was selected as an appropriate test site to measure the efficiencies of new "charged fogging" equipment in mining and mineral processing operations. EPA's Industrial Environmental Research Laboratory, Research Triangle Park, NC, contracted TRC-Environmental Consultants Inc. of Wethersfield, CT, to conduct a full-scale demonstration of a recently developed electrostatic fogger, designed to project a charged fog spray at distances up to 15.2 m. Test results indicated overall fogger efficiencies of approximately 70%. The Fogger IV* employed in these tests is reportedly the largest charged logger ever made, with an extremely long operating range. The original fogger was designed for indoor dust control; this fourth generation version is designed for fugitive dusts, indoor and outdoor, and has an operating range up to 15.2 in.

Jan 6, 1981

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 J. S. Meyer

Although salmonid fishes (including Pacific salmon and trout) have only intermediate sensitivity to copper (Cu) for traditional toxicity endpoints (survival, growth, and reproduction) and thus do not ?drive? the freshwater Cu criteria (e.g., see species-sensitivity ranking in US EPA 2007), Cu concentrations as low as 1 to 2 µg/L have been reported to impair olfaction (the sense of smell) in salmonids in laboratory experiments using dilute fresh water (see references in Meyer and Adams 2010 and DeForest et al. 2011). Olfaction is crucial to predator avoidance, recognition of kin, and reproductive synchronization (Baldwin et al. 2003); and Cu is of general ecotoxicological concern because it can be present in acid/mine rock drainage, industrial and municipal effluents, agricultural runoff, and urban stormwater runoff (Meyer et al. 2007). Therefore, there is public concern that the current regulation of Cu in surface waters is not stringent enough to protect salmonid fishes against olfactory impairment (e.g., OSU 2007; Pearson 2007). Because the toxicity of metals to aquatic organisms is a function of water chemistry [e.g., acute toxicity of Cu generally decreases as pH, water hardness (Ca2+ + Mg2+), alkalinity, and dissolved organic carbon (DOC) concentrations increase; Meyer et al. 2007], hardness-based freshwater criteria for metals are lower at lower water hardness. The recently-developed biotic ligand model (BLM) explicitly takes into account all four of those water chemistry parameters and the concentrations of other major inorganic cations (Na+, K+) and anions (Cl-, SO42-) to predict the acute toxicity of cationic metals (e.g., Ag, Cd, Cu, Ni, Pb, Zn) to aquatic organisms; and the BLM has been adopted by the U.S. Environmental Protection Agency (US EPA) to calculate acute and chronic national freshwater criteria for Cu (US EPA 2007). Consistent with observations of Cu toxicity to aquatic organisms, BLM-based Cu criteria generally are lower at lower pH, water hardness, alkalinity, and DOC concentrations. Therefore, although threshold concentrations for olfactory impairment by Cu can be low in dilute fresh waters, the corresponding hardness-based and BLM-based Cu criteria for the same waters also tend to be low. This leads to a logical question: Are Cu criteria already protective against impairment of olfaction in salmonid fishes, thus obviating the need to decrease those criteria even lower to protect against adverse effects to this physiological/ecotoxicological endpoint? Herein, we demonstrate that in all studies conducted to date, the US EPA?s BLM-based freshwater Cu criteria would have been protective against olfactory impairment in salmonid fishes, but the US EPA?s hardness-based criteria would not always have been protective. This distinction is important because all 50 States in the USA still use hardness-based Cu criteria in their water quality standards, and only some of the States allow use of the BLM to calculate site-specific Cu criteria. Additionally, in the absence of empirical results for calibration of a saltwater Cu-olfactory model, we demonstrate that a proposed unified freshwater-saltwater Cu-olfactory BLM predicts the US EPA?s current saltwater Cu criteria would be protective against olfactory impairment caused by Cu in sea water.

Feb 27, 2013

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 C. F. Barter, H. G. Kreis, D. S. Weber

Before and during in situ mining at the Santa Cruz In Situ Copper Mining Research Project test site, hydraulic testing was conducted at injection and recovery test wells to characterize patterns of fluid movement in the 5-spot well field. Testing included borehole spinner flow meter surveys, single-well and multiple-well injection and recovery tests, straddle packer injection tests, and bromide pulse tracer tests. Results of hydraulic testing for determination of fluid flow regimes were used to modify well and mining zone hydraulics for the purpose of increasing fluid migration in flow pathways of the mining zone with higher copper grade.

Jan 1, 2000

By M. Fornaro, E. Lovera, I. Sacerdote

"The analysis of the mining laws of the different European States reveals big diversities and, often, remarkable complications. This is due, firstly, to the history and culture of different States and, secondly, to the assets of natural resources. It is therefore difficult to find a common line between the text of the various mining laws, but it can be observed that nearly all the States distinguish the mining resources in two categories: the materials whose importance is considered strategic belong to the first category; in the second category the materials whose importance (above all economic) is mainly local are comprised. The paper, analysing in detail the planning procedures in some important Countries, investigates the possible perspectives of arranging some guide-lines for a correct approach to the sustainable exploitation planning/programming of mineral resources (with particular reference to "quarry" materials, such as aggregates), considering both the environment protection and the production needs."

Jan 1, 2005

By E. Topuz, C. Patrick

Longwall face-to-face transfers can cost more than $100 per minute in lost production potential and $100,000 for personnel and supplies. Such high costs make extensive planning and control of the transfer process a critical necessity for the economic feasibility of longwall operations. Operations research techniques are used for the analysis and modeling of longwall face-to-face transfers. Transfer data has been collected from companies who operate, over 35%, of the total US longwall faces. Comprehensive sequence networks of existing longwall transfers were developed; simulation was used to generate models of transfers under Carving conditions; and the economic feasibility of tine-cost tradeoffs in the transfer procedure was investigated.

Jan 1, 1994

By Karen Mikkola, Gerald Luttrell, Jaisen Kohmuench, Glen Oswald, Michael Mankosa, Tracy Westerfield

Hydraulic separators are commonly used for particle size classification and gravity concentration of minerals and coal. Unfortunately, the efficiency of these processes can be quite low due to poor equipment design and variations in feed consistency. To help alleviate these problems, an industry-driven R&D program has been undertaken to develop a new generation of hydraulic separators that are more efficient and less costly to operate and maintain. Two of the most promising technologies, the CrossFlow and HydroFloat separators, have now been tested at industrial sites. The data obtained from these sites have been used to illustrate the potential performance improvements that can be realized through the application of these high-efficiency separators.

Jan 1, 2005

Simulator technology has advanced to the point where the cost of mining equipment simulators is beginning to make commercial sense. Simulator-based evaluation allows operators or potential employees to be assessed in a pseudo-real environment under surface and underground mining conditions. Simulator training also allows operators to be exposed to emergency and advanced situations such as brake or steering failure or a tireblowout. ThoroughTec, of South Africa, provides simulator equipment to the mining industry. The company’s various packages of simulator products provide an unbiased evaluation score that removes human error from the assessment process. This same evaluation score is also presented at the end of normal training or refresher training sessions. In this way, the simulator helps eliminate bad habits and improve efficiencies.

Jan 1, 2003

By Matthew Wallin

A part of the East Bay Municipal Utility District?s Folsom South Canal Connection Project, 430 feet of raw water pipe was installed using micro tunneling beneath the Mokelumne River. The access shafts for this crossing were constructed 50 and 35 feet deep through very dense sands and soft sandstone and siltstone. High groundwater and the immediate source of recharge from the river required watertight shaft construction methods. The shaft contractor, Drill Tech of Antioch, CA, used a brand new Bauer cutter-soil mixing (CSM) rig to construct the large shafts. The structural concept is similar to secant piles, but instead of creating cylinders of soilcrete, the CSM rig creates interlocking rectangular panels. This technology has been used previously in Europe, Asia, and Canada, but this was the first project to use CSM technology in the United States. Cutter-soil mixing technology has other applications beyond shaft construction, including retaining wall construction and levee reinforcement.

By B. J. Vorster

Introduction The South African Iron and Steel Co. Ltd., in Sishen, operates a large iron ore mine in the Cape Province of the Republic of South Africa. The mine is about 600 km (370 miles) west of Johannesburg. Its annual capacity is 100 Mt (110 million st) of ore and waste. Present production is 60 Mt/a (66 million stpy). The mine operates continuously six days a week. Primary equipment includes 55 154 t (170 st) Wabco and Unit Rig trucks and 14 P&H shovels. During 1979, a feasibility study into the application of a trolley assist system was launched. This was due to the escalation in diesel fuel costs and the appeal by the South African government to reduce the use of fossil fuels. Tests and economic evaluations proved the system technically feasible. The estimated discounted cash flow return exceeded 50%. Diesel fuel consumption would be reduced by 120 ML (31.7 million gal) in the next 10 years. The construction of 7.7 km (4.8 miles) of line and the conversion of 66 154 t (170 st) trucks were completed in March 1982. System description The conventional 154 t (170 st) diesel electric rear-dump haul-truck is equipped with two direct current wheelmotors in the rear axle. They drive the rear wheels through planetary gearboxes. A 1.2-MV (1600-hp) diesel engine and an alternator is used to power the wheelmotors. The trolley assist system consists of an overhead power line, a current collector mounted on the truck, and add-on control equipment where external electric power is routed by way of the current collector to the motorized wheels. The diesel engine is used to propel the truck on level sections. On inclines, the wheel-motors of the truck are coupled by way of a current collector to the externally generated electrical power supply for propulsion. The diesel engine, having lower output than the wheelmotors, limits the truck performance. Previously, maximum output was required from an engine on inclines. By supplying the wheelmotors from a virtually unlimited outside electric energy source, the truck performance is enhanced to the extent that speed is increased by 46% and fuel consumption reduced by 75%. System design The unique operational requirements of this mine rendered the already proven trolley pole system useless. Minimum loss in truck mobility and flexibility was required. Overhead lines and substations were required to be relatively light and portable. This enables fast repositioning of a line with no loss in material. These unique specifications set the base for the design of the Sishen system. Steel I-beams, 203 x 203 mm x 52 kg/m (8 x 8 in. x 35 lb per ft) with lengths varying from 8.3 to 11.3 m (27 to 37 ft), mounted on base plates about 4 x 2.6 m (13 x 8.6 ft) were used as masts. The masts were erected at about 50 m (165 ft) and the base plates covered with about 12 t (13 st) of iron ore to keep them absolutely stable. Results from the pilot installations indicated that using single cantilever cross arms for insulator and overhead conductor suspension was not practical. The tension in the overhead varied too much with temperature changes, causing too much sag in the lines. There had to be a positive and negative conductor. It was decided to suspend each polarity on an independent cantilever and keep the conductors under constant tension by weights acting through a two-to-one pulley tensioning arrangement. For each overhead conductor, a standard 160-mm (6.5-sq in.) grooved copper railway conductor was used. To obtain the necessary current carrying capacity, two of these conductors are used in parallel per pole. Insulators are rated at 4 kV and are of the composite type. An 11-kV three-phase line, supported by the pantograph line masts on the opposite side of the dc line, feeds the rectifier stations. The rectifier stations consist of an 11-kV to 860-V, three-phase 1.46 MVA transformer and a three-phase diode bridge rectifier. The output voltage is 1200 V do earthed through a current limiting resistance network so that the line po-

Jan 4, 1986

By A. Fisne

Outburst of gas, coal and rock can be defined as sudden release of coal and rock accompanied by large quantities of gas into the working face or other mine workings. The outburst events appeared rarely in some metal mines has generally occurred in salt and coal mines especially bituminous coal mining. The most important factors that influence the occurrence of outbursts are gassiness of the coal seam, tectonics, properties of the coal and rock and vertical and lateral stresses occurring in the seam and or rock or part of the coal seam. This paper describes the problem of gas and coal outbursts in underground coal mines. The outburst events occurred in Zonguldak Coal Basin located on the Black Sea coast was investigated since 1969. Geological and gas conditions of Zonguldak Coal Basin are described. The incidents are analyzed statistically with the criteria such as amount of coal and gas outburst, depth of workings, effect of tectonism, thickness and inclination of coal seams.

Jan 1, 2012

By T. Arthur Palm, Stephen L. Bessinger

San Juan Coal Co. (SJCC) operates an underground coal mine near Farmington, NM. Continuous miners and a longwall produce 6.3 to 7.2 Mt/a (7 million to 8 million stpy). SJCC is owned and operated by BHP Billiton. The coal seam at SJCC has been shown to have a propensity for spontaneous combustion. As such, during the feasibility study for this project, it was elected to use a bleederless ventilation system on the longwall. Due to the combination of spontaneous combustion, methane liberation and, to a lesser extent, hydrogen sulfide, a typical wraparound ventilation system would not be appropriate. Three-entry gate roads are developed, and the longwall gob is sealed as mining progresses. SJCC uses a nitrogen injection system to continuously inertize the gob.

Jan 1, 2007

Due to deposit shape and dimension, narrow vein makes reserve modeling, geological control, stope design, drill and blasting more challenging. It needs high standard quality control as errors can be created easily, which could cause significant amount of ore loss or dilution. From channel sampling, survey control, reserve modeling, drill hole design, blasting, communication with underground drillers to backfill, this paper illustrated every step and its quality control of a long hole stope mining. Compared to other narrow vein mining methods (cut and fill and shrinkage), long hole stoping means higher production, less labor, and significantly lower cost when deposit characteristics allowed.

Jan 1, 2012

By R. Rushforth

The surge of activity in the solar energy market, spurred by government incentives, has created new and more efficient solar technologies, but issues surrounding land- and water-use have backlogged the full-scale development of solar farms. This paper explores siting solar power plants on degraded or polluted lands, such as mine tailings impoundments. Historically, mining and has been integral to Arizona?s economy, but has dwindled in relevance due to urban pressures and environmental regulations. Currently, it is legal to site solar power plants on degraded or polluted lands, but the question remains whether the economics of this degraded lands solar development is more favorable than developing pristine land. Therefore, we explore economics of developing mine tailings impoundments at both the institutional and financial level. Methods of research for this paper were interviews with government regulators, environmental advocacy organizations, farmers, and mining company executives. Financial models using extant tax incentives show a positive net present value for the installation of solar power plants, even when accounting for the costs of land remediation.

Jan 1, 2011