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By P. Creevy, P. F. Mousset-Jones, G. Danko, A. D. S. Gillies

The surface heat transfer coefficient is measure of the rate of heat transfer from exposed rock surfaces to the ventilating air. Knowledge of its value is of particular importance to accurately simulate the early stages of rock cooling after the opening of an excavation. A number of theoretical formulae for the calculation of the coefficient are available for use in mine climate simulation. However, direct determination by in situ measurement is preferred. Instrumentation, which has been developed for in situ mine measurement, and experimental procedures involving measurement at varying air velocities, are described. In a major study covering four Australian underground mines, the system has been used to determine surface heat transfer coefficients. A direct relationship was clearly established between the measured surface heat transfer coefficient and air velocity. Comparison is made between experimental results and those previously measured or calculated by others. The relationship established can be described by an equation and holds for air velocities above 0.4 mls. The derived relationship was con- firmed at all mines tested and is independent of geology and tunnel dimensions found in modern mines.

Jan 1, 1991

By A. L. Williamson, G. Savci

Hydrologic assessments of existing and proposed waste rock stockpiles (WRS) are typically required for application of operating and closure permits at mine sites. The results of these assessments can be used to determine the applicability of the state groundwater permit program requirements to the operation and closure of these stockpiles. The objective of this hydrologic assessment was to ascertain whether or not the WRS at the Ajo Mine have a reasonable probability of discharging potential pollutants to the underlying aquifer under the operational mine conditions. The hydrologic assessment was performed based on an evaluation of climatic data, prediction of the net infiltration rate through the WRS and prediction of additional hydrologic factors such as the time required to deplete available moisture storage in WRS. The predicted net infiltration rates ranging from 0.13 inches/year (1.1x10-8 cm/s) to 0.24 inches/year (1.9x10-8 cm/s) are below the threshold value of less than 10-7 cm/s recommended by Hutchison and Ellison (1992) as being characteristic of conditions that produce no or negligible quantities of seepage. In addition, the total time required to deplete available moisture storage within the Ajo Mine WRS and for any potential seepage from the WRS to reach the underlying aquifer is estimated to range from 260 years to 1,950 years. Collectively, the climatological and geotechnical investigations and the hydrologic predictions demonstrate that the WRS at the Ajo Mine hydrologically do not have a reasonable probability of discharging pollutants to the underlying aquifer. As a result of this prediction, the stockpile will not be regulated under the state groundwater permit program and operational and reclamation requirements will be limited to managing surface water runoff.

Jan 1, 2002

By David Caiden, Geoffrey Fosbrook, Jaidev Sankar, Donald Phillips, Jon Hurt, Anil Parikh

This paper will cover the progress being made on Phase 1 of New York’s Second Avenue Subway line. It will include a description of construction progress on the first contract to be let, which consists of a 248 m (815 ft) long launch box, 3.9 km(2.4 miles) of TBM tunnels and a tunnel sump; the packaging strategy for the remaining work; and the progress through Final Design of the remaining packages, including the two large span rock cavern stations.

Jan 1, 2007

By S. Mischler, J. Noll, G. Schnakenberg, A. Bugarski, M. Crum

Diesel particulate filter (DPF) systems and biodiesel fuels are two of the most promising technologies available to the mining industry to reduce the exposure of underground miners to diesel particulate matter (DPM). A study has been conducted to estimate the potential of DPF systems and biodiesel blends to reduce DPM emissions from production vehicles. Results of testing three DPF systems in an isolated zone showed 88% to 99% reductions in elemental carbon concentrations. The test results also show that biodiesel blends, B20 and B50, reduced the elemental carbon concentrations in the mine air by 26 and 48 percent, respectively.

Jan 1, 2004

By R. L. Grayson

Conventional mine safety wisdom states that "the most efficient mines are also the safest." Since the 1980s, small mines (and contractors) have been targeted as the most dangerous ones because of their fatality records. Statistical testing of 1993 West Virginia safety and production data indicated that the most efficient WV mines were not the safest ones, considering correlations between the severity measure and tons per employee-hour, except for very small mines. This paper will present the results of an extended analysis of WV mine safety using 1993 and 1996 data, concluding with the method used to suggest current priorities for focusing interventions.

Jan 1, 1998

By Ellsworth R. Spencer

An assessment of U.S. western hardrock miners? noise exposures was conducted as part of a multi-year National Institute for Occupational Safety and Health (NIOSH) survey of noise exposures in each sector of the mining industry. Noise from selected mining equipment and operator noise exposures were measured, analyzed and tabulated for dissemination to the participating sites and are being used to direct NIOSH research and interventions to address the greatest noise hazards. Eighty-two noise dosimeter measurements were obtained, along with time-motion studies as the miners operated hardrock mining machines. Of the operators, 96% had daily noise doses that exceeded the U.S. Mine Safety and Health Administration?s (MSHA) permissible exposure level. The average gold miner dosages while operating the following equipment were: haul trucks - 261%, load-haul-dumps (LHDs) - 235%, single boom drills - 221%, bolters - 214% and dual boom drills - 163%. The worst exposure level was a silver miner with a daily dose of 873%. Time-motion data showed that this miner?s exposure accumulated most rapidly while operating a jackleg drill. These results will be used to help prioritize noise control development by NIOSH and other partners.

Jan 3, 2010

By Terry W. Mellors, Robert J. F. Goodfellow

The underground industry has been forced to reconsider risk management sincethe introduction and implementation of the “Joint Code of Practice for Risk Management of Underground Works in the UK” published in 2003 and the subsequent international version published by the ‘International Tunneling Insurance Group’ (ITIG) in January 2006.What does this mean for major tunnel projects in the US and elsewhere? The discussion will highlight the implementation of the Codes to date, risk management principles embodied in the Codes and the use of risk registers as a projectmanagement tool and the management of risk.

Jan 1, 2007

By K. W. Grubaugh

Indigenous people are nearly always affected when projects enter their territory. Crop and other asset compensation can help or undermine a project’s progress depending on the approach. When compensation is handled poorly, a technically viable project can get indefinitely entangled by local unrest. Stake holders associated with compensation issues include; the state, the indigenous people, non-governmental organizations, and the developer. Appreciation for the unique perspective of indigenous peoples and the influences affecting them can avert problems and prevent delays. A review of the compensation issues encountered in Ghana during its recent gold boom can assist in avoiding problems associated with handling poor and uneducated people.

Jan 1, 2002

By Douglas B. Silver

Traditional cycle theory would postulate that if you have a supply shortage relative to demand, the price will increase because buyers will incrementally increase the price they are willing to pay to ensure that their needs are fulfilled. As prices rise, more supply will be brought on and will eventually exceed demand. This supply excess will cause the price to decline as producers have to lower their prices to sell their goods. What is interesting is that cycles are simply volatility over time. Without the time factor, volatility simply goes up and down. When we add the time element, a cycle is created. This cycle can be big or small. In mining?s case, we are talking about a Super Cycle ? a big cycle. But a Su-per Cycle can be formed in two ways. It can form by either increasing the wavelength or the volatility. If these two elements are combined, a Super Cycle is formed. It is bigger than the normal cycle in terms of time duration and extent of volatility. A recent study (Fig. 1) conducted by Cuddington and Jarrett showed an interesting proof of Super Cycles and suggests that these cycles last between 15 and 30 years. So, what causes a Su-per Cycle? Is it a convergence of unrelated events or a consequence of related events? In a global community everything is related. Equilibrium theory would also take the position that a Super Cycle is a consequence of events.

Jan 1, 2008

By Jerry C. Tien

Mining in China dates back at least 4,000 years. Today, with no less than 103,000 metal/nonmetal mines and between 40,000 to 80,000 coal mines, China’s mining industry is undoubtedly the largest in the world. Despite improvements in recent decades, seemingly endless mining accidents continue to make the news. Official coal mining deaths were 6,702 in 2003, and 6,027 miners died in 2004; actual figures may be much higher. Added to these were the 2,699 deaths in the metal and nonmetal industries. Most of these accidents were due to CH4 (methane gas) explosions and fires as a result of inadequate mine ventilation de-sign or practices. A good portion of these accidents occur in small, privately run and often technically illegal mines. During the past 10 years, the Chinese government has attempted to crack down on small and often technically illegal mines without much success. The number of accidents and associated fatalities has not significantly reduced. However, there appears to be a new urgency in China’s efforts to step up mine safety in the country. After its worst reported mine disaster in more than a half century, the government quickly paid reparations to families, suspended high-level officials in charge and announced additonal reforms. One of those was the elevation of the central government’s work safety office to cabinet-level status. There has been increased transparency in reporting and investigation of mine accidents and disasters in recent years. There has also been an increase in public criticism by labor leaders concerning the neglect of mine workersafety.1 This article examines the causes of China’s many mining accidents, current legal and enforcement structures, respective mining health and safety related laws and regulations, recent mining industry developments and the latest effort to curtail small mining operations.

Jan 1, 2005

By W. F. Visser

The growing availability of information and data analysis capabilities of recent years provides new opportunities for improving the performance of mining operations. By using real-time measurements and artificial intelligence, it is possible to respond faster to changing conditions, while accurate and timely information permits rapid evaluation of changes and fast business improvement decisions. This article presents a blueprint for alignment of systems, organizational design, and management practices to leverage these developments in performance-driven operations management in mining and mineral processing. The first component of the blueprint is a performance framework with a system of key performance indicators for production control that can be used across organizational levels. This system places improvement at the core of management activities, giving greater importance to improvement skills at lower organizational levels, so companies can leverage available information for improving operational control. Secondly, the blueprint defines an organizational structure that strengthens performance improvement with technological and change management capabilities. Finally, the blueprint proposes alignment of management practices, covering the optimization of short-interval controls, the application of an improvement project portfolio management system that determines the ownership of improvement projects, and the coordination of controls across the organization. This combination of systems, organizational design, and management alignment supports rapid decision-making at the right organizational level. Introduction of the presented blueprint for operations management enables mines to leverage the developments in information and analysis capabilities to improve the performance of operations.

By Danqing Gao, Brijes Mishra

Spatial variance of rock properties is an important characteristic of rock which addresses the heterogeneity of mechanical and physical properties and their effect on underground mining. Assessing spatial variance can be useful for both locating potential difficult grounds and performing reliability analysis in the mining support system. This study shows a microscale numerical model for rock material based on continuum mechanics. To consider the spatial correlation factor of mechanical properties in realistic rock mass, this study introduces a spatial correlation concept into the traditional type III extreme value distribution model. Based on the improved microscale random model, we conducted a series of numerical uniaxial compressive tests and one longwall mine model to investigate the progressive failure of rock. The results show that spatial correlation factor can significantly affect the load-deformation curves and fracture patterns. The spatial variance model was applied to a longwall mine that included several cutting sequences to observe the influence of the spatial variance on roof behavior. The cohesion and friction random fields induced failure that propagated randomly through the immediate roof in different entries. The results showed that the spatial variance provides an accurate prediction of erratic roof falls in coal mines.

Jul 20, 2020

By Elisa Comis, Jeffrey Peterson, Yama Ebrahimi

Construction of the Northeast Boundary Tunnel (NEBT), the last leg of the Anacostia River Tunnel System on DC Water’s Clean Rivers Project, started in September 2018 and was completed in April 2021. The 26-foot-bore earth pressure balance (EPB) tunnel boring machine (TBM) mined 26,737 feet at elevations between 80 to 160 feet belowground. Approximately 55% of the tunnel was cut through lower predominantly coarse-grained facies identified as the Cretaceous Patuxent Formation (undifferentiated) (PTX), and the remainder was cut through upper predominantly overconsolidated fine-grained plastic material facies identified as the Cretaceous Patapsco/Arundel Formation (P/A). Mixed face conditions were encountered in the transition from the P/A to the PTX and vice versa. This paper reviews the performance of the TBM that mined the NEBT through several unique challenges, including 8,000 feet of tunneling under the heavily developed Rhode Island Avenue corridor, major sensitive structures, cast iron water distribution mains, and other sensitive utilities.

Dec 1, 2022

By Charles G. Zink

Anthracite is widely known as a domestic or space heating fuel. The prevailing market ratio of domestic to industrial consumption was about 80 to 20 up until 1950. Since then it has been shifting until now the ratio index is about 50/50, exclusive of overseas export. Despite a declining domestic space heating market, the demand for industrial anthracite remains good. However, as a result of stringent air pollution regulations, there is a renewed interest in this low sulphur coal which cannot smoke under any conditions. Anthracite serves other important industries such as power generating, metallurgical, cement, ceramic, chemical, water sewage and industrial wastes filtration. Anthracite is an excellent natural source of carbon and may be utilized in many processes.

Jan 1, 1966

By John Keefner, Charles Kocsis, Kyle A. Scalise

Geotechnical modeling of mines is crucial for understanding the many factors that can pose potential hazards or limit production opportunities. The process of back analyses for modeling is often used, but in many instances, the back analyses can be cumbersome and time inefficient.While thesemodels and back analyses may be accurate, these types of back analyses may not be ideal to be used at mines and by engineers because the process is so time-consuming. This paper introduces event-based back analyses that utilize prior events to create more accurate models while eliminating large modeling time because the models are back analyzed from previous events. The completed analyses supply a more detailed insight into the potential hazards at Round Mountain, an open pit operation, as well as provide a better understanding of how improper risk analysis results in missed opportunities. The more we understand about mining activities and processes through modeling, the safer and more productive mines will be.

May 24, 2021

By A. Nivala, S. Ulgiati, M. Canino

Mining and processing of bastnaesite ore, (Ln)CO3F, for lanthanides extraction is investigated in this paper. This series of elements proved to be applicable for a wide range of high-tech uses. In spite of the strategic importance of lanthanides, no LCA and energy analyses of their extraction have ever been published. We perform in this paper a Life Cycle Assessment of the Lanthanide production cycle, based on available database and literature data from Mountain Pass mine (USA) and other worldwide mining and processing sites, most of which in China. We investigated three main steps: mining, milling (including transport, grinding and drying), and flotation (for lanthanide chloride extraction). We do not investigate here the separation of pure oxides from lanthanide chloride, a compound which is also marketed as such. The conventional LCA was integrated by means of energy and emergy evaluations, aimed at investigating respectively the global energy cost and the environmental sustainability of the process. Indicators of material intensity, thermodynamic efficiency, and environmental impact (including LCA and ecological footprint impact categories) are calculated and discussed.

Jan 1, 2005

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 K. Nielsen

The paper presents a brief overview of the mineral industry in Norway, followed by a description of the mineral policy and relevant legislation including the roles of the Norwegian Directorate of Mining and Geological Survey of Norway in this context. The discussion then proceeds to describe the land use planning framework on a national, regional and local level, the interaction between land use planning and the Directorate of Mining and the Geological Survey respectively, and how this impacts on the mineral industry and the exploitation of mineral resources. Some recent Norwegian examples of land use planning conflicts are also presented.

Jan 1, 2005

In 2011, the value of mineral production increased in the United States for the second consecutive year (Table 1). Production increased modestly for most mineral commodities mined in the United States, and price increases, especially for precious metals, resulted in increases in the value of production. Minerals remained fundamental to the U.S. economy, contributing to the real gross domestic product (GDP) at several levels, including mining, processing and manufacturing finished products. Minerals? contribution to the GDP increased for the second consecutive year. Trends in other sectors of the domestic economy were similar to those in mineral production and consumption rates. U.S. apparent mineral consumption (industrial) of 11 mineral commodities decreased substantially from 2005 to 2010 (aluminum, cadmium, cement, copper, iron, lead, salt, soda ash, steel, tin and zinc). Data for 2011 were not calculated, but the data show a sustained decrease (especially for the metals) preceding the recession through 2010, so consumption seems to be behaving differently than production and GDP. After continued decline following the 2008?2009 recession, the construction industry began to show signs of improvement during 2011, with increased production and consumption of cement, construction sand and gravel, and gypsum ? mineral commodities that are used almost exclusively in construction. Crushed stone production, however, continued to decline.

Jan 1, 2012

By M. Santillan

Minerales Monclova S.A. de C.V. (MIMOSA) has applied different methane gas drainage technologies, according to the top industry requirements in order to keep the methane gas at the lowest possible concentration in our operations, both in the development sections and longwall sections. Our staff has used the horizontal rotary technique. In 2004 MIMOSA bought a re-built drill machine and signed a contract with Resource Enterprises Inc. (REI), which included a training program in Horizontal Directional Drilling using the reflex system. The training system was developed for a period of three months in Mine VII, with very good performance by the MIMOSA staff. After the training the equipment was moved to Esmeralda Mine, where we had already drilled holes at the development section, 2,500 ft. It was the longest distance that could be reached with our original equipment, obviously; the directional drilling program is another challenge for us and our staff, but we are very confident that our result will be better every time. We will be evaluating each borehole and expect to improve our results in each progressive borehole, until we can drill up to the capacity of the equipment. We are in the process of buying another drill with an electronic monitoring device (DD DMecca) in the following months.

Jan 1, 2009