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By Taehong Kim

An accurate and reliable prediction of Tunnel Boring Machine (TBM) performances, in terms of Rate of Penetration (ROP), utilization (U), and cutter wear rate, is a critical element in the successful planning and execution of mechanical tunneling project. Three open hard rock TBM projects were studied to establish possible trends and correlations between rock mass properties and machine performance. Based on this analysis and literature survey, three geological parameters, including RQD, RMR, and groundwater inflow rate, were identified as having the greatest impact on TBM utilization level. Rate of Penetration (ROP) and cutter wear rate were also correlated with fracture spacing, alpha angle, and Cerchar Abrasivity Index (CAI).

Jan 1, 2008

By W. H. Langer

At the start of the 20th century Denver?s population was 203,795. Most streets were unpaved. Buildings were constructed of wood frame or masonry. Transport was by horse-drawn-wagon or rail. Statewide, aggregate consumption was less than 0.25 metric tons per person per year. One hundred years later Denver had a population of 2,365,345. Today Denver is a major metropolitan area at the crossroads of two interstates, home to a new international airport, and in the process of expanding its light rail transit system. The skyline is punctuated with skyscrapers. The urban center is surrounded with edge cities. These changes required huge amounts of aggregate. Statewide, aggregate consumption increased 50 fold to over 13 metric tons per person per year. Denver has a large potential supply of aggregate, but sand and gravel quality decreases downstream from the mountain front and potential sources of crushed stone occur in areas prized for their scenic beauty. These issues, along with urban encroachment and citizen opposition, have complicated aggregate development and have paved a new path for future aggregate development including sustainable resource management and reclamation techniques.

Jan 1, 2009

Worldwide minerals exploration slipped in 1992 from 1991 levels. Although industrial production figures showed the US economy emerging from recession in early 1992, it was not until February 1993 that the lagging indicator of unemployment dropped to 7%. Most other industrialized countries are still in recession. Preliminary data for 1992 showed industrial production dropping in Japan (5%), Germany (1.4%), the United Kingdom (0.5%) and France (1.4%). The slowdown in industrial production led to reduced mineral demand. This resulted in lean cash flows from mining operations, which squeezed exploration funding. Although mineral prices were steady during most of 1992, some mineral commodity prices began falling in late 1992 and early this year. Exploration 1991-1992 According to Metals Economics Group (MEG), planned 1992 exploration expenditures were down by about 5%. Geographically, the leading exploration target was the United States with 21 % of the expenditures, followed by Australia (19%), Canada (18%), Latin America (15%), South Africa (9%) and the western Pacific (7.5%). The remaining 10% was split between Europe and Africa. There were absolute increases in exploration expenditures in the United States and Latin America. Latin America showed the largest increase. The change in the Mexican mining law allowing foreign ownership of mines should result in the inflow of direct foreign investment in Mexico's mining industry.

Jan 1, 1993

By REHMAN ATTA UR, Kwame Awuah-Offei

This work evaluated the effects of bucket orientation and operating parameters on resistive forces and penetration for rubber-tire loaders (RTLs), such as load-haul-dumps (LHDs) and front-end loaders (FELs). The work used a 1:16 scale LHD model to test an RTL bucket operating at different levels of traction (tractive effort), speed, digging height and rake angles in a full factorial design experiment. The test was repeated on two muck piles with different particle sizes, and generalized regression modeling was applied to test the association of rake angle, tractive effort, speed and digging height on penetration and resistive forces for RTL buckets. The results show that speed and tractive effort are more important in explaining RTL penetration and resistive forces than height above the floor and rake angle. Speed, tractive effort and height above the floor are positively correlated to bucket penetration, whereas the rake angle is negatively correlated to penetration. Similarly, speed, tractive effort, rake angle and height above the floor are all positively correlated to resistive forces incurred during initial penetration. The results show that the combined effect of speed and tractive effort is negatively correlated to penetration and resistive forces — a novel finding that enhances our understanding of RTL loading. The results also show that the effects of speed, tractive effort and height above the floor all change with changes in particle sizes. This work provides insights into the effects of rake angle, height above the floor, tractive effort and speed on penetration and resistive forces for RTLs to facilitate better design and efficient use of these loaders.

By P. J. Doig

The LCLS project at SLAC will allow new insights into material properties, chemical reactions and biological processes. The project includes half a mile of new underground construction. Excavation in weathered rock is by NATM, using AM 50 roadheaders. Construction began in 2006 and is expected to be completed in 2008. This paper details the construction of the tunnels and cavern on the project.

Jan 1, 2008

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

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

Oct 1, 2023

By K. J. Stanaway

Major world ilmenite and rutile accumulations reveal similar regional geology and Proterozoic age deeper crustal source rocks. During crustal collision titanium crystallizes as ilmenite and rutile at buried sites of high pressure and temperature rock metamorphism. Hydrothermal activity can convert titanium minerals to rutile, but titanium migration and enrichment seem only local. Many melts crystallize rocks with iron-titanium oxides in solid solution, but titanium enrichment at economic scale takes place in basic intrusive melts often associated with anorthosites and charnokite. Sedimentary placer enrichments have formed since the Proterozoic with water-resistant ilmenite, and rutile segregating by gravity from quartz sands deposited from flowing water. Placers have residual, alluvial, strand and shallow marine variants. Time, organic acids, and sand permeability play lead roles in the leaching of iron from ilmenite during weathering and diagenesis.

Jan 1, 2005

By Vojtech Gall

Pre-support measures for urban tunneling have seen a substantial development in the recent past. Ground improvement techniques, pipe-arch and spiling methods now allow for non-disruptive tunneling at very shallow depths under sensitive structures, rail tracks and roadways. The paper presents experience gained on national and international projects built over the past decade that represent case histories and therefore may be used as guidance for the development of similar solutions for future tunneling projects at shallow depths. Reference projects include tunnels for the Washington, DC Metro, London Underground, Dulles Inter-national Airport, Busway tunnels in Boston and the Ft. Canning Tunnel in Singapore.

Jan 1, 2008

By Fouad Faraj

For every blast pattern, zones of unique material types need to be classified before mining. Most material types can be summarized into different kinds of ore and waste. Blocks generated from blasthole assays are too small to be selectively mined, so areas with a single material classification meeting the mine’s selective mining unit must be defined. Current industry standard practices are to manually draw ore/waste dig limits, but this process is subjective and results in quantities of dilution and ore loss that can be improved upon to enhance the profitability of mining operations. In this study, two weeks of production data from a homogeneous copper (Cu) porphyry and heterogeneous manto-type Cu deposit were used to assess the variability in the hand-drawn dig limits of 20 geologists, mining engineers and ore control specialists, which were compared with the optimal ore/waste delineation. The profit for 20 distinct hand-drawn dig limits for the homogeneous mine varied by 3.7 percent, from $10.5 million to $10.9 million, averaging at $10.8 million. The percentage was nearly double for the more heterogeneous mine at 5.9 percent, from $17.9 million to $19.0 million, averaging at $18.6 million. Using the optimal ore waste delineation, the profit increased to $11.0 million (1.9 percent increase) and $19.3 million (7.0 percent increase) for the homogeneous and heterogeneous deposit, respectively. The natural variability, diggability requirement and selectivity are identified as the main drivers of ore loss and dilution. Recommendations are provided for reducing the subjectivity in manual hand-drawn dig limits by integrating dig limit optimization algorithms as a tool to assist practitioners.

Oct 1, 2024

Contributions made by mining have played a much more significant role in the development of civilization than is generally conceded by historians or recognized by ordinary citizens. In modern society, mined products pervade all industry and the lives of all civilized people. Early man relied largely on stone and ceramics, and eventually metals, to fashion tools and weapons. Civilization was advanced by discoveries such as abundant supplies of high-quality flint in northern France and southern England and firesetting to break rock. Middle Eastern cultures flourished not only because of agriculture and trade, but also because of mineral-rich deposits nearby. The earliest miners date back perhaps to 300,000 BC; their quest was for nonmetallic minerals (chert, flint, obsidian) suitable for utensils and eventually for weapons. Other rocks and minerals (ceramics, clay, salt, meteoric iron) attracted the miners for jewelry, cosmetics, construction materials, food seasoning, and coinage. At first, their excavations were confined to the surface, either pits or placers. But by about 40,000 BC, mine workings had been extended underground as short adits or shafts, and by 8000 BC as elaborate interconnected openings 300 ft (90 m) in depth. Metallurgical separation of metals from their ores and their subsequent fabrication evolved gradually over the centuries, copper being the first liberated (c. 7000 BC) followed by lead, silver, gold, and iron. Man enhanced both the sophistication of his

Jan 1, 2008

By Peter Klaver

Deep tunnels have been used for decades for the temporary storage of large volumes of urban runoff, both storm water and combined sewer overflow (CSO). Tunnels are attractive because they reduce surface disruption and do double duty as storage and conveyance systems, collecting overflows from multiple locations and transporting them for treatment to various facilities. Like any hydraulic system, however, there are dynamic effects that must be fully understood during the design phase so that the final constructed product does not have unintended negative consequences. Preliminary sizing of storage tunnels is typically based on the total volume required. For example, if studies have determined that a volume of 56.8 ML (15 million gal) will provide the intended level of control, then that figure can be used, along with a preliminary idea of the desired tunnel length, to compute the required diameter. Of course, filling a long tube with water from various points along the way is not at all the same as pouring water into a bucket, and these dynamic effects require additional attention from design engineers. The rapid filling of storage tunnels can lead to the formation of bores, which are essentially moving walls of water. An open channel bore can build in height until it reaches the crown of the tunnel, at which point it becomes a pipe-filling bore. Figure 1 depicts both kinds of bores moving upwards in a rapidly filling tunnel. Bores can strike the ends of tun-nels with tremendous force, driving water and entrained air upwards into dropshafts and creating strong pressure surges in portions of the tunnel that are already filled. If the hydraulic surges are high enough to reach grade, they can cause overflows and/or damage structures at the surface. Trapped air pockets can occur through several phenomena, including the reflection of bores off dropshaft structures and the occurrence of ?premature pressurization.? The latter refers to the situation where the inflow to a tunnel is increasing more rapidly than the tunnel can convey it, such that the pipe becomes surcharged at an upstream point while points downstream are still flowing as an open channel. These air pockets are a great nuisance as they migrate toward points in the tunnel where they can rise to the surface, which are often shafts that are already filled with water (Fig. 2). The ?geyersing? that results can be hazardous and costly.

Jan 3, 2010

By Dennis P. Martin, Michael M. Fitz, James E. Friant

Methods for reducing the cyclic nature of drill and blast tunneling operations have been long needed. A miniature blasting system using 10 mm (.375 in.) holes, 0.91 m (36 in.) deep, and blasting only one hole at a time makes it practical for men to work behind a shield, remaining at the face during the entire process. A prototype automated module was developed to drill, load the hole and initiate the detonation without moving from the hole. A unique cost effective gell explosive and a novel, low cost initiation method were developed.

Jan 1, 1989

By Zoë Mullard

The introduction of Web 2.0 platforms (also referred to as social media), with their architectures of participation, has ushered in a new era of technological interaction and information exchange that is changing the nature of corporate-community communications. Web 2.0 platforms give users the ability to generate data collaboratively, meaning that more stakeholders maintain the expectation of being able to contribute to online dialogue. In light of these changes, it is important for business to consider how social media can be used strategically to enhance stakeholder relationships and increase business efficiencies. This article provides three case studies of how different stakeholders in the mining industry are strategically using Web 2.0 platforms to communicate with target audiences. The case studies are based on the experience of respondents and from website observations, which were undertaken as part of a thesis research project by the first author (Mullard, 2010), focusing on the application of social media in the mining industry.

Jan 1, 2011

By Jayant Khambekar

In a typical mining operation, run-of-mine (ROM) ore is crushed and screened to achieve a desired particle size distribution and then fed to processing equipment for further refining. For an operation to be profit-able, the ore handling system from the mine face to final product loadout must be reliable. However, the handling system components do not always perform as expected and production problems related to material flow occur. These problems include flow stoppages, limited live storage capacities, uncontrollable flow, segregation, spillage and dust emissions. These result in lost production, excessive maintenance, safety and environmental issues, and even structural failures, in some cases. Flow patterns Flow problems and their solutions can be best understood by first learning how bulk solids flow. As bulk solids discharge by gravity from a storage system, primarily two types of flow patterns can develop: funnel flow and mass flow. Figure 1 shows a schematic of these two flow patterns. In funnel flow, only a portion of the material is in motion during discharge, which flows toward the outlet through a channel that forms within the stagnant material. Funnel flow occurs when a hopper is not sufficiently steep and smooth to ensure flow along the walls or when the outlet is not fully effective. In mass flow, all of the material is in motion whenever any is discharged ? there is no stagnant material. Mass flow occurs when the hopper is sufficiently steep and smooth to ensure flow along the hopper walls. Shallow valleys are not permitted and the outlet must be fully effective. A third type of flow pattern, called expanded flow, can develop when a mass flow hopper (or hoppers) is placed beneath a funnel flow hopper or bin. The mass flow hopper is designed to activate a sufficiently large flow channel in the funnel flow hopper to avoid flow problems due to a rathole. The flow pattern in which a bulk solid discharges from a storage system strongly influences the flow problems that may occur in that facility.

Jan 1, 2009

By M. K. Mohanty, H. Akbari, L. A. Ackah

Dry separation was the predominant method of coal cleaning in the United States from the 1930s to 1980s. The application peak of dry separators for cleaning raw coal was in 1965, when about 23.1 Mt of cleaned bituminous coal was produced. The main advantage of dry coal cleaning is the elimination RIWKH GHZDWHULQJ VWDJHV DQG VLJQL¿FDQWO\ UHGXFHG moisture in comparison to wet processing. In addition, developed dust control systems have made dry cleaning method an environmentally friendly process. The largest air-based coal cleaning plant was built in Pennsylvania in 1968 and could clean 1,272 t/h of raw coal sized smaller than 19 mm. This was followed by a decline in dry coal cleaning to less than 3.6 Mt in 1988. Some of the main reasons that shifted coal operations IURPGU\WRZHWSURFHVVLQJZHUHWKHQHHGIRUPRUHHI¿FLHQW separations with lower density cuts, increase in raw coal surIDFHPRLVWXUHVSHFL¿FDOO\LQXQGHUJURXQGPLQLQJWRFRQWURO GXVW ¿QHUSDUWLFOHVL]HUHTXLUHPHQWV LQFUHDVHLQ¿QHVLQUDZ coal from underground mines, and health and safety concerns related to dust and noise (Arnold, Hervol and Leonard III, 1991; Miller, 2011).

By Joe Roby

Rolling disc cutters are the business end of hard rock and mixed face tunnel boring machines (TBMs). Since their first successful employment on a TBM over fifty years ago, disc cutter technology has constantly evolved, allowing modern TBMs to excavate very hard and abrasive rock efficiently. Disc cutters have also been employed successfully on earth pressure balance (EPB) and slurry machines, cutting rock under water and ground pressure. The range of materials excavated by machines today is broader, excavation rates higher and cutter costs lower than ever before, proving the value of investment in cutter development. This paper describes recent improvements in disc cutter components including cutter ring materials and processing, as well as improvements in lubricants, bearings, seals and cutter condition monitoring. These developments have resulted in more reliable cutters capable of operating in a wide range of geological conditions. Ultimately these improvements result in a better value for both contractors and project owners.

Jan 1, 2008

To gather additional field data from the western United States, researchers from the National Institute for Occupational Safety and Health (NIOSH) installed an array of field instrumentation at a longwall coal mine in Central Utah. The purpose of this field site was to monitor ground movement and changes in pressure during mining where conditions include massive, stiff overburden and relatively deep cover. To accomplish this, field instrumentation was installed in the two-entry gate road between the fifth and sixth longwall panel in the current mining district.

Jan 7, 2020

By Scott Thayer, Michael Murphy, Natalie Cope, Gabriel Esterhuizen, Anthony Iannacchione, Tim Miller, Brent Slaker

"The Subtropolis room-and-pillar mine extracts the Vanport Limestone (Allegheny Formation, Pennsylvanian System) near Petersburg, Ohio. Strata instability problems associated with excessive concentrations of lateral stress caused the mine operator to implement a change in layout design. This mining method has been identified as a stress control layout, which has been used by other underground stone mines in the past with varying degrees of success. Practical experience has shown that entry headings advance in the direction of the principal lateral stress, producing lower stress concentrations with better mining conditions. It is important to minimize stress concentrations along the mining front, so an arrow-shaped advance is recommended. This technique advances more developments (headings) in a “good” direction and reduces developments (crosscuts) in a “bad” direction. As is expected, the stress control layout enhances the potential for shear failures in crosscuts. It is, therefore, important to focus crosscut engineering interventions that either: (a) lower stress concentrations (for example, an arched roof) or (b) enhance strength of the strata containing the shears (for example, rock reinforcement). This study focuses on observing strata conditions on a regular basis and monitoring the response of this strata to changing geologic and mining conditions through 3D Dynamic LiDAR scans.INTRODUCTIONProject AimsThe Subtropolis Mine is extracting the Vanport Limestone in northeastern Ohio. Since the start of mining in 2006, ground conditions have been significantly affected by excessive lateral stress condition. In some other mining districts with this hazard, certain mine layouts have been shown to lessen the potential for unstable ground conditions. The term “lessen” is used to state the realization that stress concentrations are not eliminated but instead occur in less frequency and intensity, and their locations can be projected.The stress-control mine layout, specifically for large-opening room-and-pillar stone mines, naturally evolved at mines suffering from excessive lateral stress problems. These mines will typically experiment with methods to mitigate adverse impacts, thus developing best practices for their conditions. These practices have evolved into a basic framework for the stress control mine layout. For example, Jack Parker was able to write about personal experiences at the White Pine Mine in Michigan (Parker, 1966, 1973). Various researchers at the U.S. Bureau of Mines (USBM), the Mine Safety and Health Administration (MSHA), and the National Institute for Occupational Safety and Health (NIOSH) have studied the effectiveness of stress-control mine layouts over a wide range of geologic conditions (Emery, 1964; Mark and Mucho, 1994; Iannacchione et al., 2003). While the stress control layout design approach has proven successful in many categories, it can be difficult to implement. For example, excessive stress conditions in crosscuts can put the ground control focused intervention at odds with ventilation and haulage constraints, thus limiting optimal crosscut size, shape, and location. Therefore, more information on the effectiveness of this approach is needed."

Jan 1, 2019

By G. Bierie

The conveying of bulk materials is prone to problems. These problems can reduce the capacity and efficiency of the plant, and even threaten the health and safety of the workforce. This presentation will look at new conveyor technologies systems, and how, used separately or in combination, they can improve material handling.

Jan 1, 2007

By H. Richard Eisenbeis, Donna M. Watkins

Many technical professionals (tp)* desire to occupy upper level management positions. But career paths for most scientists and engineers do not extend beyond their specific disciplines. This is unfortunate. Our technical frontiers are expanding so rapdily that it is difficult, if not impossible, to make sound top management decisions without understanding the technical complexities involved. Technical professionals often are not considered for upper level management positions because they lack the managerial and interpersonal skills necessary to become successful administrators. You've heard this before, but a key component of these skills is the ability to communicate. Technical professionals are often unable to communicate as well as they should with nontechnical professionals and nonprofessionals within the organizations that employ them. Communication is important for managerial success Communication is the network of interactions whereby knowledge and understanding are conveyed from one social set to another (Flippo and Munsinger, 1982). In order to be successful, managers must not only be "good" communicators, they must be "effective" communicators as well. Good communication occurs when managers are able to formulate and transmit their messages in such a way that they are received and understood. Effective communication goes one step further: It occurs when recipients accept messages as legitimate and respond to these messages in the manner desired. Before promotion into upper level positions, managers must have developed organizational skills (planning, decision making, organizing, and controlling) and interpersonal skills (directing, influencing, and motivating). Applying these skills effectively is difficult without a highly refined ability to communicate. Effective communication, then, is basic to managerial success. Nowhere, perhaps, has the importance of being able to communicate effectively been emphasized more than in Mintzberg's landmark study of managerial roles (Mintzberg, 1973). Mintzberg's results indicate that executives typically averaged 36 written and 16 verbal contacts a day. These contacts were both important and trivial. They generally occurred in a random manner. Time spent on each varied. Scheduled meetings averaged over an hour. Desk work, telephone calls, and unscheduled meetings required an average of 15 minutes or less. Why technical professionals have difficulty communicating Three reasons why technical professionals do not communicate well are: • The work motivational patterns and personal attitudes of technical professionals are not conducive to effective communication. • Students in technical professions are not encouraged by educational institutions to develop their communication skills. • Organizations do not insist that all technical professionals be able to communicate in the language of business. The work motivational patterns of most technical professionals are indicative of internals and high achievers (Hunt, Salisbury, and Whittington, 1968). As internals, they believe they control their own destinies. As high achievers, they believe that task accomplishment is a primary indicator of success. To ensure a task is completed in the manner desired, tp's attempt to structure and define work situations so they alone are responsible for results. TPs consider the task accomplished when they, and perhaps other tp's, are satisfied with the results. From the tp's perspective, the task may have been completed. From a communication standpoint, two other factors may apply. First, solving the problem required very little interaction (and thus, communication) with others. Second, the tp's, considering the task accomplished, have little concern for how their "technical" answers will be translated to nontechnical persons needing

Jan 8, 1987