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By Niels Kofoed

Upon completion of the 6,200 m (20,340 lineal ft; lft) North Tunnel drive for the Portland East Side Combined Sewer Overflow (CSO) Tunnel project in Portland, OR, the slurry tunnel boring machine (TBM) had to be returned from the Port Center shaft at Swan Island to the Opera shaft at the main mining site for the 2,700 m (8,860 lft) South Tunnel drive. At the Port Center shaft, the main 513-t (565-st) TBM and TBM tailshield were hoisted out of the shaft in two pieces using four 200-t (220-st) strand jacks mounted on a 635-t (700-st) hydraulic boom gantry system supported by Emmert International?s custom gantry tracks designed to span the shaft. After lifting the TBM components out of the shaft, the gantry system loaded the TBM components onto two Goldhofer platform trailers, which then transported the TBM and tailshield to a barge using a roll-on/roll-off method.

Jan 1, 2011

By L. C. Stone, J. C. Parr, T. N. Anderson, D. Metcalf

An increase in the importance of low-grade materials as sources of gold and silver has led to the need for improved analytical methods on leach solutions, ores and various effluents, residues, and in-process streams. These are required by plant operators as guides to process control and for accounting pldrposes. Atomic absorption spectrophotometry (AAS) and AAS preceded by pre- concentration have been applied successfully to resolve many such problems. However, AAS is no panacea and imprecision or loss of accuracy can result if adequate precautions are not taken to prevent losses and eliminate interferences. The recent methods are discussed together with methods for overcoming difficulties. Comparisons with more classical analytical techniques are also given.

Jan 1, 1981

By P. Schilizzi, A. Jarosz, M. Karmis

This paper is concerned with subsidence prediction methods and in particular with two techniques, one based on profile functions and the other on influence functions. Profile function methods provide a tool for a fast calculation of subsidence on a line across a mine panel. Influence function methods, on the other hand, allow for a more detailed calculation of ground movements, in any mode and at any depth, on a grid or at any specific point. In more detail, the hyperbolic tangent profile function, as developed by VPI&SU from field data pertaining to the eastern U.S. coalfields, and an influence function method currently being adapted for the same region, are presented and discussed. The applicability, advantages and limitations of these techniques are examined and comparisons are presented with field measurements. Computer software developed for the application of these prediction methods, for two widely used personal computer systems, are also discussed and a number of examples are presented demonstrating the potential of such programs.

Jan 1, 1986

By Bradford F. Townsend, Colin R. Speers

INTRODUCTION This is the first in a series of papers addressing practical tunnel lining design. The format for this and future papers is to present a particular topic and support the presentation of the guidelines by the practical application of a case history. The primary intent is to provide guidelines for the geotechnical and structural design of tunnels where the tunnel size and/or ground conditions dictates that systematic support of the excavation is required following each increment of excavation. This method of tunneling is commonly referred to as Sequential Excavation and Support(SES) and is also commonly termed the New Austrian Tunneling Method (NATM) The authors developed the design guidelines from experience gained over the past two decades during the design and construction of several major railway, highway and water-transfer tunnel projects in Africa and Asia. During this time it has been possible to compare the performance of the as-constructed structures to the predicted performance as given by the design process. Excavation was typically carried out in widely varying ground conditions (weak-bedded rock, jointed hard rock, and soil-like poorly cemented rock with groundwater). It is therefore intended that the design guidelines could be applied, in general terms at least, to any tunnel excavated in any ground mass condition with any ground material type (hard rock, soft rock, bedded rock, soft ground, and soil) with or without ground water. This first paper is an introductory paper that defines the scope and a brief outline of the design issues that may be presented in detail in later papers. What is design? It may be thought of as any rational/verifiable/justifiable process whereby a concept is transformed into information that can be used to bring the concept to reality. In the case of a civil structure, design may be defined as that process, which is documented and can be audited, that determines information such as the shape (form) of the structure, the dimensions (size) of the structure, the thickness and strength of structural members that comprise the structure, etc. This information can be used to compute the time, money and resources required for

Jan 1, 2005

By Jennifer L. Bell, PATRICK L. YORIO, Emily J. Haas, Susan M. Moore, Lee A. Greenawald

Although researchers have struggled to replicate Heinrich’s safety triangle findings (Heinrich 1931) for various reasons (e.g., no access to his original database and it is unclear if the database was of a single establishment/operation or for an entire industry), the occupational safety community has continued to adopt and expand the applications of this theory (e.g., McSween 2003). Within the mining industry, the potential exists for operations and companies to use concepts from the safety triangle as a way to inform or challenge the practices employed within their health and safety management systems (HSMS) to prevent incidents (Backlund 2016). This paper considers data obtained from the Mine Safety and Health Administration’s databases and demonstrates the validity of applying the safety triangle theory at the mine level. The results support the use of this theory and demonstrate that lower severity incidents can predict fatalities in a subsequent year where significant nuances and caveats to applying the theory are identified and discussed.

Jul 25, 2020

By Richard Kastner, Emilie Vanoudheusden, Fabrice Emeriault, Jacques Robert

INTRODUCTION The subway line B of Toulouse (France) has been realized with three different tunnel boring machines (TBM) techniques: Contracts 2 and 5 are excavated with earth-pressure balanced TBM, Contract 4 with a slurry shield TBM, and Contract 3 with a compressed-air TBM. The first three machines are around 7.7 m in diameter, while the last one is 5.3 m. Moreover, a small part of the line (50 m) has been excavated by a conventional method. The tunnels run through the Toulouse molasses, composed of hard sandy clay with pockets and lenses of dense sand. Geotechnical investigations have shown that in these formations, K0 is greater than 1, around 1.8 at a depth of 25 m (Serratrice,2005) and that geotechnical characteristics are homogenous on the whole layout (? =22 kN/m3, Su = 300 kPa, c' = 30 kPa, F' = 32°). The water table is found between 2 and4 m below ground level. As geology, stratigraphy and tunnel cover (between 10 and 20 m) are almost identical, a comparison of movements induced by the excavation by each of the four excavation techniques is possible. This paper presents the soil mass movement measures in the case of the conventional excavation method and in the case of TBM sections. It shows how tunneling parameters may explain the different surface movements observed during excavation. For the sake of simplicity, only the results of Contract 2 (earth pressure balanced TBM)will be presented. MONITORING Monitoring for the Conventional Method Section For the conventional method section (Vanoudheusden et al. 2005) the mass soil movements are measured with two inclinometers and one multi-point extensometer borehole with automatic data acquisition (Figure 1). The monitoring devices include

Jan 1, 2007

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 Juan P. Camus

Mining is one of the oldest industrial activities. Its products are essential to modern civilization. Paradoxically, and despite a deep-rooted belief to the contrary, mining is not a lucrative industry— at least not in the aggregate. This assertion is true not only for recent years, one of the weakest periods in terms of metal prices, but also for a long time past. In 1776,Adam Smith said in The Wealth of Nations: “Of all those expensive and uncertain projects, how-ever, which bring bankruptcy upon the greater part of the people who engage in them, there is none perhaps more perfectly ruinous than the search after ... mines. It is perhaps the most disadvantageous lottery in the world... Projects of mining, instead of replacing the capital employed in them, ... commonly absorb both capital and profits.”

Jan 1, 2002

By Robert L. Hautala

In 1978, Congress established a series of mineral institutes for a limited time to assist financially in mineral industry education and research. Later, education and research were separated, establishing generic institutes for specialized research that transferred the former research budget from the base mineral institutes program. One of the generic institutes is the Mine Systems Design and Ground Control (MSDGC). It provides for research funding specifically for mining. Other parallel generic institutes were established in pyrometallurgy, comminution, waste management, etc. MSDGC was established at Virginia Polytechnic Institute and State University(VPI). The founding group included the University of Alabama, University of Kentucky, University of Nevada Reno, University of Idaho and University of Alaska reporting through VPI to the US Bureau of Mines (USBM) and Congress. Other universities also participated on an ad hoc basis.

Jan 1, 1996

By Patrick J. Doig

In mid-1991, the design/build contractor set to work on the Pergau HEP in a remote corner of Malaysia, armed with only a slim volume of conceptual drawings. The next five years saw roads, power lines, buildings, dams, and over 30 kilometers of tunnel constructed, followed by two years of E&M installation and commissioning. Along the way, the project overcame geothermal groundwater, faults, land disputes, monsoon rains, marauding tigers, and those most fearsome of foes, politicians and the press. This paper is a testament to the ingenuity, commitment, and persistence of the construction industry professionals who brought this massive project to fruition.

Jan 1, 2001

By R. J. Latino

Because of the lack of a universally accepted definition or standard for RCA, we are left to our own conventions in the marketplace as to what is most ?effective? or a ?Best Practice? for our own facilities or organization. This lack of uniformity in the application of RCA produces an equal lack of uniformity in the measureable outcomes of RCA on the bottom-line from site to site and industry to industry. What is the definition of success for an RCA? Is it regulatory compliance? Is it some quantifiable measure of bottom-line performance? Is compliance and bottom-line performance the same thing? Can we measure the ROI we receive by doing compliant RCA? These questions must be adequately addressed if any definition of RCA is to be effective on the bottom-line. Like our various Corporate Vision and Mission Statements, what would be our Vision and Mission for RCA? When pondering the answer to this question, we should consider: ? What Key Performance Indicators will the Success of RCA be Linked to? This provides a direct correlation to the corporate dashboard and therefore garners support for the RCA effort when implemented at the sharp end. Not until we know what KPI?s will effectively measure our maintenance and reliability objectives can we begin to establish which opportunities will afford the greatest returns1. ? What Bottom-Line Metrics will be Tracked to Measure the Effectiveness of Our RCA Effort? Will it be increased production, profitability, regulatory compliance, etc.? Will it be decreased injuries/fatalities, claims, customer complaints, risks, etc.? We should be specific about these metrics and their correlation to the metrics on our corporate dashboard. ? What Will Trigger an RCA Investigation? Normally companies will establish quantifiable thresholds to be surpassed before an RCA will be conducted. Examples may be an OSHA recordable injury, a failure event in which production losses exceed $250,000, an equipment failure in excess of $50,000 or a regulatory violation. This is the norm. However, we should realize this is using our RCA skills totally on a reactive basis. High Reliability Organizations (HRO) strive for proaction and they also use RCA proactively. Why can?t we use RCA to analyze why unacceptable risks from an FMEA are so high? It is perfectly applicable yet rarely implemented in this fashion.

Feb 27, 2013

By Joseph M. McCann

The Brightwater regional wastewater treatment facility, under construction in King County, WA, includes an extensive conveyance system that will feature deep, soft-ground tunnels and shafts. Excavation of the Ballinger Way Receiving Portal to 65.8 m (216 ft) below grade through challenging geology was accomplished by means of artificial ground freezing. This paper discusses freeze design development, system installation and monitoring, and the contractual and construction challenges that were overcome, including work sequencing and excavation means and methods, together with lessons learned.

Overcasts are indispensible ventilation control devices to permit one airway to pass over another without mixing in room and pillar coal mining. The airflow distribution inside the overcast depends on its spe-cific configuration at which the flow enters into it. This study uses 3D numerical simulation to examine the pressure and velocity distributions inside an overcast. The effects of the overcast angle on the flow field are also examined. The flow is assumed to be turbulent and isothermal and the standard k-e model is utilized. Simulated results display flow separation and recirculation regions of different sizes occurring not only upstream and downstream from the overcast but also inside it. The results also show that the size of the recirculation regions in-creased with the increase in the angle before and after the overcast influencing significantly the flow field and pressure losses. The stream-lines are plotted to show the 3D structure of the flow field. The results from the simulation can guide overcast design commonly used in un-derground coal mines. Keywords: 3-D simulation, Overcast, Room and Pillar, Turbulence, Recirculation Region

Feb 27, 2013

By Georgene Renner, William R. Yernberg, Steve Kral

ABB offers complete electrical revamps of mining shovels with ac or dc drives, drive control, frequency converters with insular gate bi-polar transistor technology, intelligent control packages and visualization. Many of the world’s shovel excavators and draglines (walking excavators) were built in the1980s. After 15 to 20 years of round-the clock operation in openpit mines, these machines start to feel their age. Electrical parts are particularly vulnerable. Their performance deteriorates and availability and productivity fall. Even with regular ser-vice and maintenance, a machine of this age will accumulate 400 hours of unscheduled downtime a year. The need for a replacement becomes pressing, but the expense is often prohibitive.

Jan 1, 2005

For the past four years, the Department of Mining Engineering at the University of Kentucky has conducted a validation study of the CFD Fluent code, by comparing its results against mining-related benchmark experimental data provided by NIOSH?s Pittsburgh Research Laboratory. This particular study is dedicated to the effect of machine-mounted dust scrubbers on the performance of face ventilation systems using extended-cut mining with a blowing curtain.

Jan 1, 2009

By M. Bennett, L. Twidwell

Montana Tech has embarked on a coordinated series of studies to delineate the characteristics of the Berkeley Pitlake containing over 36 billion gallons of acidic, metal-contaminated water formed after the cessation of open-pit copper mining in Butte, Montana, USA. The objectives of the overall series of studies are to summarize presently available information and to generate new and needed information to formulate a conceptual environmental model for the pitlake and to provide characterization data for the development of advanced treatment technologies. In this presentation, the chemistry of the Berkeley Pitlake water is partially reviewed. It is known that the pitlake consists of two distinct layers of water referred to as surface and deep water. Samples of deep water were collected and placed in a 12-ft high and 6-inch diameter column and exposed to different wavelengths of UV radiation as well as atmospheric conditions. Measurements of pH, redox potential (EH), dissolved O2, turbidity, conductivity, temperature, and elemental composition show that the water reacts differently and indicates that the diurnal effects of sunlight likely play a major non-biological role in its chemistry. Resulting technology could be useful for developing an alternative to treating acid-rock drainage.

Jan 1, 2007

By M. J. Farrell

The threat of global warming and its prominent position in public discussion and political debate requires all industry to take stock of its contribution to rising atmospheric concentration of greenhouse gases. For the primary metals industry, the first step must be to identify the pattern and range of emissions at each step in the production chain. Only then can the industry assess the economic consequences of the penalties on emissions that will be imposed by governments and regulators and devise cost-effective plans to avoid or mitigate such penalties. While some work has been done to estimate carbon dioxide (CO2) emissions using Life Cycle Inventory analysis, this approach is less useful than site-by-site emissions estimates. It is the level of specific emissions at each site that will ultimately deter-mine carbon taxation liabilities and participation in emissions trading schemes. Most mining companies have moved with the times to issue sustainability reports for their operations. But in the absence of any standardized reporting format, it is difficult to make useful comparisons between even the best-reported producers on a like-with-like basis. For this reason, Minecost.com modeled the use of fuels and energy used in mining, milling, shipping and metallurgical treatment to cover ?cradle-to-gate? emissions of greenhouse gases resulting from the production of the major base metals copper, zinc, lead and nickel. Greenhouse gas emissions ? overwhelmingly carbon dioxide ? are associated with the consumption of energy at every step in the production chain, from exploration through mining to the production of refined metal. Producers of primary metal employ diverse technologies to mine, mill, smelt and refine several different types of ore. Every orebody has its own special characteristics. In addition, most base metals are produced in concentrate that must be transported to smelters, with con-sequent emissions consequences.

Jan 1, 2009

By Wilfred P. Schmoe

Introduction An integrated oil company has two options in approaching strategic planning. It has to decide whether it is in business for the long-term. I state this in all seriousness. Those who help manage public companies have the responsibility of good stewardship of other people's money. We must decide whether continued investment in our basic business will generate a reasonable rate of return. With a world surplus of petroleum production capacity, and continuing downward pressure on prices, this question should be addressed by all oil companies. And a positive answer is not necessarily a foregone conclusion in all cases. The decision should be made based on proven competence in finding and developing petroleum reserves on a cost-competitive basis with other producers, and on a frank analysis of future prospects. This should include a realistic assessment of the projected rate of return on specific investment projects. If a company did not pass these tests, its strategy could take one of four paths. Diversification First, it could diversify. But recent history suggests that oil companies are not good at managing other businesses. Second, it could seek a buyer for its business at the optimum return for its owners. Third, it could sell its assets on a piecemeal basis. And, fourth, it could adopt a longer-range plan of self-liquidation by living off current recoverable reserves. In other words, by not investing in exploration and development, it could maximize short-term profit and pass the money back to shareholders in the form of dividends. The Conoco component of DuPont has a below-average cost of finding petroleum, a good track record of efficient production, and a full plate of projects that pass the test of return-on-investment. In short, Conoco is in business for the long-term. That fact, in itself, determines at least one key element in strategy. This is to extend the life of the petroleum reserve base while at the same time maintaining maximum efficient rates of production to provide a strong cash flow. A company that is able to maintain a strong reserve base will ultimately see the value of those reserves escalate as world oil supplies tighten. Our planners expect this tightening to occur within the next decade as demand grows and production in non-OPEC areas of the world begins to decline. An exploration program tailored to meet the requirements of reserve replacement and current production should have two basic parts. The first is relatively low-risk exploration in proven oil provinces. This is augmented by

Jan 6, 1985

By J. D. Potts

Dust surveys were conducted at six underground coal mines to determine if deep-cutting practices expose face workers to higher levels of respirable dust. The surveyed mines were able to successfully mine deep cuts without significantly increasing the dust exposures of face workers. For exhausting face ventilation, field data indicate that scrubber airflow is the most important factor for controlling dust. Data collected for this study indicate that 20-mesh screens should be cleaned for every 40 ft of advance because 22% of the deep cuts surveyed for this study experienced a 20% to 35% decrease in scrubber airflow over the course of the cut. For blowing face ventilation, field data and past research indicate that dust control is aided by maintaining a proper curtain-to-scrubber airflow ratio of 1.0 (measured before scrubber activation) as well as a curtain setback distance that allows the miner operator to stand at the mouth of the curtain for the entire cut. Dust levels on the bolting faces did not appear to be affected by the longer cycles associated with deep-cut mining when good ventilation practices were used.

Jan 1, 2011

By Heiner J. Sander

Stanford University operates the National Research Facility which is located at the Stanford Linear Accelerator Center (SLAC) in Menlo Park, California. In order to improve and allow for enhanced experiments, the current facilities required expansion. A1500 foot long tunnel (20 ft wide by 21 ft high) and a 220 foot long underground cavern (49 ft wide by 32 ft high) were excavated through the Ladera Sandstone formation which is an intermediate geo-material with week rock properties. The overburden between surface and crown of the structures varies from 10 to 80 feet. The underground structures were excavated according to the principles of the NATM (New Austrian Tunnel Method). This paper addresses the challenges that were encountered during the construction phase of the project and how construction issues were resolved mutually by the owner, engineer and contractor. The implementation of geotechnical instrumentation, recorded data and interpretations, soil conditions and behavior encountered during construction are also presented.

Jan 1, 2008