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By Verya Nasri

The proposed Second Avenue Subway Project in New York City is approximately 8.5 miles long, up to a depth of 120 feet beneath grade and runs the length of the eastern side of the island of Manhattan from Harlem in the north to the financial district in the south. It will reduce overcrowding and delays on the existing parallel line, improving travel for both city and suburban commuters, and upgrading access to mass transit for residents of the East Side of Manhattan. This subway line will have 16 new stations providing transfers to the existing Metro-North commuter rail service and to New York City Transit subway lines and bus services. The first phase of construction includes two TBM rock tunnels 2.4 miles long and two new large and shallow rock cavern stations with clear span openings ranging from 70 to 100 feet and length in excess of 1000 feet with 615 feet center platform, coupled with low rock cover ranging from 20 feet to 40 feet. The design methodology for these large and shallow rock caverns consists of using well known empirical methods for initial estimate of support requirements and then two and three dimensional continuum and discontinuum analyses for verification of the selected excavation sequence and support system. This paper describes the analysis and design methodologies used for the two large and shallow rock caverns with insight into how to overcome the design complexities and construction challenges of the urban underground.

Jan 1, 2008

By J. B. Gwiazda

S.S. Peng The highlights of this paper are : • The shield supports with lemniscate links will exert a tangential force on the roof strata, causing unnecessary and harmful roof movements, thus damaging the roof structure. The principal source of the tangential force is the horizontal movement of the point O, the pivotal joint between the canopy and the caving shield. When the support height is changed during setting, the point O will move along a curve upward and rearward toward the gob. As a result, it produces a vertical movement, causing the roof to move up a distance of ?d, and a horizontal movement toward the gob, creating vertical fractures in the roof. • The major purpose for employing the lemniscate-link system is to protect the hydraulic legs against the action of the bending moments induced by the tangential force that causes deformation or destruction of the legs. • Based on these two points, the author suggested that, in order to eliminate the harmful effects of the lemniscate-link system and strengthen its advantageous features, a shield support with a new design of that mechanism has been developed. With the new design, the conventional rigid lemniscate links are replaced by hydraulic rams. When the pressure inside the rams reaches a certain level, the ram will yield.

Jan 12, 1986

By Colin Lawrence, Michael S. Schultz

Due to the planned deepening of the NY Harbor, NYCEDC/NYCDEP is planning to replace two existing water lines between Brooklyn and Staten Island with one deeper water pipe. The crossing, just north of the Verrazanno Bridge is 1.75 miles long. The new pipeline will be tunneled using gasketed concreted segmented liners. Apressurized face machine will be used through the soft ground. This will be the first subaqueous application using this technology in New York City. This paper discusses the planning, design and risk issues associated with the crossing and the challenging soil conditions that resulted in the decision to use a pressurized face machine.

Jan 1, 2007

By Kerry Spickelmier

Editor's note: information for this feature was taken from the published APCOM proceedings. Computer trends, with special focus on the reasons for computer use, grabbed the lion's share of attention at the 23rd worldwide meeting on the Application of Computers and Operations Research in the Mineral Industry (APCOM 23). However, technical topics did not provide the meeting's sole focus. The last-minute inability of certain former communist countries to fund the travels of a few scheduled speakers was a reminder that science does not operate in a void. As with all technical progress, the APCOM presentations raised interesting questions regarding interrelated organizational dynamics and political and socioeconomic issues. Consider US Bureau of Mines (USBM) research to design an expert control systems to "duplicate" an experienced, "good" operator during automated underground roof bolting. In his presentation of the project, Takach, Jr. stressed the importance of preserving the ability to switch from automatic to manual drilling control. From a technical standpoint, this allows the expert system to "learn" from a good operator. As important, he said, is that this flexibility decreases the human operator's sense of being replaced by the machine. The question arises: Which will loom larger in union minds, increased operator safety through remote opera¬tion or the potential for total operator replacement? Like any new product, computer technology relies on marketing to aid its acceptance and use. Consider, too, a decision support system, by Schena and Gochin, for mineral resource management in a developing country. The authors said "the analysis permits the assessment of the overall socioeconomic consequences of mineral prospects and allows incorpo-

Jan 1, 1992

Recent advances in GPS, machine guidance technology and telemetry allow an unprecedented level of control of surface mining operations. GPS technology can now locate the bucket of a shovel or the blade of a dozer within 50mm (2 inches).Some of the outcomes possible are: precise selective mining – even when the ore is visually indistinguishable from waste: tracking grade and tonnage of every ore parcel through the mine: real time productivity monitoring: detailed post accident safety analysis: tracking the movements of every piece of equipment. This paper will consider the contribution that GPS based machine control systems can make to ensuring that surface mining projects deliver the outcomes promised in the feasibility studies. Case studies of installations are presented.

Jan 1, 2004

By R. L. Wiegel

Several mineral process modeling and simulation packages are currently available for use in evaluating the performance of alternative process flowschemes. A critical link that has been missing from these packages is the ability to quantitatively model the effect of size reduction on the liberation of the valuable and waste minerals in the ore being processed. Although there have been several approaches taken to this problem over the past 25 years, none has led to a satisfactory conclusion. A technique has been developed for measuring the effective liberation characteristics of magnetic taconite ores, and a program has been constructed which makes use of these liberation characteristics in simultaneously simulating both size reduction and mineral liberation as it occurs in tumbling mills. This is an especially important step in the modeling of magnetic taconite processes, where magnetic rejection of low grade wastes between grinding stages mandates that a predictive capability be available. The current application is specific to magnetic taconite, but it is possible that a similar approach could be used for other types of mineral systems.

Jan 1, 2002

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 W. L. Jacobsen, T. L. Dyer

Cortez Gold Mines is completing a Feasibility Study for a new open pit gold mine in north central NV. The production schedule calls for a peak in material movement. This schedule is based on current operational efficiencies and equipment parameters observed at the company’s existing open pit operation. To mitigate risks of over/under predicting production, simulation modeling was used to validate the loading and haulage requirements during the peak production period. The advantage of simulation is the ability to provide a realistic model of a mining operation based on scheduled, and unscheduled random events during the period under analysis.

Jan 1, 2006

By Gary English

"Tunnel safety is evolving as science, engineering and technology make advances. Applicable safety codes and standards simply do not cover all the potentials of design, construction and operation. This paper reviews a series of tunnel projects code gaps in Seattle USA that were uncovered during the design and construction of a new highway tunnel, conversion of bus tunnels to combined road and rail tunnels, new rail tunnels using TBM and NATM, conversion of a road tunnel to light rail, and retrofit of an existing road tunnel to add lanes and improve safety systems. The perspectives of the ‘fire code official’ (Authority Having Jurisdiction) on methods to identify and resolve gaps in safety code and standard regulations, while garnering the consensus of the owner, designer, and contractors are presented. Additionally, the emergency responder command perspective on safe tunnel design, tunnel rescue during construction and operational safety is explained TUNNEL SAFETY EVOLUTION The underground has become nearly the only option to provide essential transportation corridors to continue our economic growth in key global areas. Tunnels are not built on a whim. Often significant portion of a regions wealth are invested to meet current, and hopefully future transportation demands. There are more transportation tunnels being built now than at any time in the planets history. The location of these tunnels is often selected for us based upon regional demand. Most commonly under densely populated urban centers and between populations’ centers to bypass geologic conditions like mountains and water bodies. Tunnels are being built in unforgiving soils, between tectonic plates, in extremes environmental conditions and often, under the very heart of the highest density population centers on the planet. All of these locations can bring with it conditions that challenge our common assumptions about safety. These extraordinary locations and soils create risks for both those constructing the tunnel, and in design engineering to meet the ‘minimum’ requirements at the lowest costs. There is lengthy history of above ground safety. Most countries and major local jurisdictions have adopted, or created safety requirements for the construction of above ground buildings. Through decades of use, these safety requirements have evolved, changed and been expanded to cover a wide gamut of actual and potential safety risks. However, the use of the underground for tunnel transportation corridors has grown exponentially with limited attention to safety requirements."

Jan 1, 2016

By D. Royston

SAG mill liner development draws primarily on practical experience from SAG milling operations supported by computer-based modeling of charge motion in SAG mills and on established good design practice. Liner design needs to respond to the process aspects of mill liner action that are critical to good SAG mill performance, i.e., the impact of shell liners on the grinding action and of grates and pulp lifters on pulp discharge. In recent years, the trend in large SAG mills has been to use wide-spaced shell lifters with large lifter face angles, primarily to reduce packing and ball/liner damage, and to use larger, hence fewer, mill liner parts to reduce downtime at liner change-outs.

Jan 1, 2007

By RICKARD HANSEN

With vehicles frequently found in underground mines and tyres being a major fuel item, the risk of tyre fires will be severe underground. This study presents an in-depth analysis of tyre fires on mining vehicles to increase the knowledge of the risk, applying data from full-scale fire experiments and CFD simulations. It was found that the wheelhouse of the loader caused an increase in the flame tilt angle of approximately 10%, decreasing the flame impingement and heat flux downstream. The flame temperature of the drilling rig tyre was found to be approximately 7% higher than the loader tyre, increasing the risk of igniting adjacent fuel items. The construction of the wheelhouse/mudguard will contribute to a longer flame length by creating a fuel-rich environment. The CFD simulations predicted higher flame tilt angles for the drilling rig case for higher flow velocities, indicating the influence of a varying wheelhouse/mudguard construction and tyre geometry on the flame tilt angle. The construction of the loader resulted in a flow behaviour, where the short distance to the front mudguard/tyre and the separation of flow directly downstream of the protruding construction led to fire gases being steered past the front mudguard/tyre. In the drilling rig case, the longer distance to the front mudguard/tyre led to fire gases being directed towards the body of the vehicle after passing the area with flow separation. An increased knowledge of the tyre fire risk on mining vehicles and mitigating measures would improve the fire safety in underground mines.

Feb 10, 2022

By E. Siami-Irdemoosa, S. R. Dindarloo

"Pareto analysis was used to investigate the failures database of a Hitachi EX1900 hydraulic shovel over one year of continuous operation. The hydraulic system and hydraulic links, hoses and piping were identified as the most critical system and subsystem, respectively. A three-parameter gamma distribution function was identified as the best fit for a probabilistic modeling of the time between failures (TBFs). This distribution was used in a Monte Carlo reliability analysis of the hydraulic system. Autoregressive integrated moving average (ARIMA), within the context of a time series analysis of the TBFs, was proposed as a viable alternative to the traditional technique of distribution fitting. The mean absolute percentage error (MAPE) metric was used to compare the two models. The MAPE value that resulted from the ARIMA was 66 percent smaller than that from the traditional technique in predicting the TBFs. Resumen ¦ Se usó análisis Pareto para investigar la base de datos de fallas de una pala hidráulica Hitachi EX1900 durante un periodo de un año de operación continua. Se identificó al sistema hidráulico y a los enlaces hidráulicos, mangueras y tuberías como el sistema y subsistema más importantes, respectivamente. Se identificó una función de distribución de tres parámetros gamma como el más apto para un modelado de probabilidades del tiempo transcurrido entre las fallas (Tabes por sus siglas en inglés). Esta distribución fue usada en un análisis de confiabilidad Monte Carlo para un sistema hidráulico. El promedio de movimiento integrado auto-regresivo (ARIMA por sus siglas en inglés), dentro del contexto de análisis de serie temporal de los TBFs, fue propuesto como una alternativa viable a la tradicional técnica de ajuste de distribución. Se usó el porcentaje de la media absoluta de error (MAPE) para comparar los dos modelos. El valor MAPE que resultó de la ARIMA fue 66 por ciento menor que el resultado obtenido con la técnica tradicional de predicción de TBFs."

Jan 1, 2015

By Pierre Filiatreault, Brian Straight, Stephanie Thibeault, Devin Castendyk, Londie Cameron

"Working on or near water at active, closed or abandoned mine sites is inherently dangerous. Between 1996 and 1999, the U.S. Mine Safety and Health Administration (MSHA) reported 17 fatalities involving drowning at U.S. metal, non metal and coal mines (MSHA, 2000). Openpit mines which fill with water following mine closure, called pit lakes, present numerous risks to environmental monitoring teams including: a) drowning, b) hypothermia, c) falls to the ground from the top of high walls, d) collapse of unstable access roads, e) rock falls and avalanches from pit walls, f) avalanchegenerated tsunamis traveling across the lake surface and g) rapid degassing events.Some pit lakes are simply not safely or easily accessible for ongoing monitoring. However, the routine collection of water samples from the entire water column on a regular basis is needed to monitor the evolution of water quality over time, verify the accuracy of numerical predictions and, ultimately, manage lake water chemistry and ecological risks. For pit lakes with surface water discharge, regular monitoring is used to appropriately design and adjust water treatment plants in order to produce acceptable site discharge water quality.As a product of these risks and the need for water samples, mining companies spend considerable expense on pit lake safety as part of monitoring programs. This includes training personnel for on water duties and hazards, purchasing or hiring specialized equipment and personnel (such as boats, boat operators, personal floatation devices and cold-water clothing called mustang suits), stabilizing pit walls and maintaining safe access roads to the lake surface and employing spotters who can directly communicate with emergency medical services to watch sampling activities because cell phones and radio signals can be blocked by pit walls. Some sites utilize redundancy to prepare for unexpected incidents and accidents. For example, one Canadian mining company requires two boats on the water during pit lake sampling events, with a third boat on the shoreline, gassed and ready to go. In addition, water samplers are required to hold Marine Emergency Duties training to ensure the entire boat crew is sufficient and competent for the safe operation of the vessel in the event of an accident."

Jan 7, 2017

By P. L. M. Wong, N. W. Johnson

Surface analysis by X-Ray Photoelectron Spectroscopy (XPS) of samples taken from the galena flotation section of the Hilton Concentrator of Mount Isa Mines Limited are presented. Flotation rate and pulp chemical data taken during the sampling period are also presented and discussed. Surface analysis suggested that, under normal operating conditions, an overlayer of precipitated calcium sulfate existed at the surface of the sulfide minerals. In particular, there was a decrease in the surface concentration of calcium sulfate for the concentrate samples relative to that occurring on the tailing samples. This suggests that the flotation process was selective against minerals which have calcium sulfate predominating at the surface. Heterocoagulation of hydrophilic calcium sulfate on to the galena surface considerably reduced galena flotation rate. Methods to control calcium sulfate precipitation, which include sodium carbonate treatment of the pulp, are also discussed. Sur- face analysis results of samples taken from the Hilton Concentrator during sodium carbonate addition to the grinding circuit are also presented. This shows clear evidence for the removal of calcium sulfate from the mineral surfaces without concomitant surface precipitation of calcium carbonate. Reasons for the apparent dispersion of precipitated calcium carbonate are discussed. Galena flotation rate was increased by the addition of sodium carbonate apparently due to the removal of interfering calcium sulfate.

Jan 1, 1995

Magnetic separation is an age-old technique for mineral beneficiation operations. The existing mathematical models for magnetic separators are quite complicated, and it is very difficult to measure the theoretical separation efficiency. The connectionist approach of modeling, to establish the relationships of the inputs and outputs, is preferred for this kind of problem. Experiments were carried out on a high-intensity roll magnetic separator to develop a database using four input variables (magnetic flux intensity, particle size, splitter position and roll speed) and two output variables (weight recovery and Fe recovery). The artificial neural network (ANN) and statistical methods (MLRG) were used to model the magnetic separation process. For the ANN, the regression coefficient (R2) values between the predicted and measured results were 0.89 and 0.94 for Fe recovery and weight recovery, respectively. Compared to ANN, the multivariable linear regression analysis showed inferior performance in predicting the weight recovery and the Fe recovery. The ANN models for the roll magnetic separator can predict the separation efficiency up to an acceptable limit. These models can be used to modify the operational parameters at mineral beneficiation plants to minimize the effects of variations in the raw material characteristics.

Jan 1, 2009

By Jeremy Morris

The city of Indianapolis has more than 25,000 homes currently on septic systems. Many of these systems do not function well because of their age and surrounding soil conditions. As Indianapolis has worked to eliminate septic systems and install sanitary sewers in large unsewered areas on the north-west side, capacity of the existing Belmont North Interceptor (BNI) became a concern. The BNI system currently services an area of approximately 80 km2 (31 sq miles) located within the northwest quadrant of the city (Fig. 1). Monitoring of the existing interceptor indicated portions of the sys-tem flowing half- to two-thirds full during dry weather conditions and surcharging during some wet weather conditions. Further analysis of the BNI based on growth projections coupled with increased sewershed yield resulting from the city?s septic tank elimination program (STEP) indicated dry-weather flows could potentially triple over the next 20 years. Based on these modeling results and current wet weather capacity issues, the city determined further STEP projects could not be performed within the BNI service area until

Jan 1, 2011

By J. H. Rowland

The Mine Improvement and New Emergency Response Act of 2006 (MINER Act) amended the Federal Mine Safety and Health Act of 1977 to improve the safety of mines. The MINER Act established a Technical Study Panel (the Panel) to provide independent scientific and engineering review and recommendations with respect to the utilization of belt air and the composition and fire retardant materials in underground coal mining (1). Because frictional heating is a common cause of belt fires, the Panel recommended that the Mine Safety and Health Administration (MSHA) evaluate the drum friction test to determine if such a test would contribute to conveyor belt safety beyond that provided by the Belt Evaluation Laboratory Test (BELT). This paper compares the results of the drum friction test to results from the BELT and large-scale tests for six different conveyor belts. The results are used to evaluate the drum friction test as a method to determine the fire resistance of conveyor belts.

Jan 1, 2011

The 28th annual American Mining Hall of Fame Awards Banquet and fundraiser sponsored by the Mining Foundation of the Southwest will be held at the Marriott University Park Hotel, Tucson, AZ on Saturday, Dec. 4, 2010. The Mining Foundation of the Southwest is a nonprofit organization whose objectives are public education about the mineral industries, and recognition of outstanding accomplishments in and contributions to the fields of mineral and fuel resources. Funds are being raised to the support the foundation?s educational programs. Among these is the Educational Outreach Program operated jointly by the foundation and the Arizona Department of Mines and Mineral Resources.

Jan 1, 2010

By S. E. Phillipson, P. L. Tyrna

Lineament analysis, a remote sensing application for geological structures, has been criticized for reliance on subjective interpretations. The Mine Safety & Health Administration’s Roof Control Division performs lineament analyses with a technique that removes much subjectivity. Study areas are viewed on satellite images with software that allows examination under artificial sun azimuths and elevations. Extraneous lineaments are removed through successive steps of superposition, resulting in selection of the most robust linear features. Field investigations revealed a strong coincidence of joint and fault zones that were parallel with projected lineaments. The Roof Control Division’s successful identification of lineaments associated with roof falls and highwall failures has prompted some mine managers to incorporate lineament analysis as a mine-planning tool. The identification of potentially hazardous ground conditions will allow mine operators to obviate safety concerns that might otherwise adversely affect miner health and safety.

Jan 1, 2002

By F. Dahl, P. Raleigh, J. Holzhauser, B. Nilsen

Tunnel excavation using tunnel boring machines (TBMs), has become increasingly common in recent years, despite the fact that precise evaluation of certain risks have not kept pace with the use of these machines. One of the risks easily overlooked by Engineer and Contractor alike are the effects of abrasive ground on the costs and schedule of a given project. The impacts of worn and damaged TBM cutter heads have been observed on hundreds of tunnel projects around the world. It would appear that a reliable prognosis of the abrasiveness of soils on a project would be of great importance for designers, clients and contractors alike. Several well acknowledged test and prognosis methods already exist for rock, however there is only very limited knowledge available to describe the abrasiveness of soil and its impact on soft ground TBMs. This paper will examine approaches to this problem and suggest a new approach based on a current project undergoing design.

Jan 1, 2007