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By E. Topuz

The objective of mine ventilation is to provide suitable environmental conditions in working places at an economical cost. Maintaining a stable air flow, i.e., a flow quantity and the direction, is of vital importance. In practice, however, air flow quantity in underground openings varies continuously. Therefore, the stability of air flow means relative stability that is the flow in a branch moves along a certain direction while the variation in air quantity stays within acceptable limits. Many underground mines have low stability of mine air flow because almost all types of ventilation systems involve complex diagonal branches through which air flow quantity and, more importantly, the air flow direction may change easily. This creates extremely hazardous, unstable conditions, especially during emergencies. This paper deals with the directional stability of air flows in underground mines in single or multiple fan systems. It examines the rules of directional changes of air flows in diagonal branches, and proposes a method of calculating the stability conditions. It provides a criterion that may be used in designing new mine ventilation systems to ensure a desired degree of stability or in improving the existing systems.

Jan 1, 1986

By E. Topuz

This paper discusses factors affecting the productivity of continuous coal mining operations. It analyzes design and operational relationships in continuous mining systems, and investigates how their productivity can be improved by selecting the number of headings, the dimensions of pillars, and the depth of cuts as well as the miner loading rate and tramming speed, the shuttle car payload and hauling speed, and the roof bolting cycle time. A computer simulator has been found very efficient in analyzing effects of section layouts and equipment operating characteristics on the productivity of continuous coal mining systems.

Jan 1, 1987

By M. F. Vancas

The advantages of using vertical pulsed columns as replacements for conventional mixer/settlers in the uranium industry have been known for some time. The advantages of the columns offer include a reduction in real estate for the plant, elimination of diluent evaporation and crud formation. This paper presents the findings of laboratory tests of pulsed columns extracting copper from pregnant leach solutions and also discusses potential advantages of the pulse column in copper solvent extraction.

Jan 1, 1999

By Alfred C. Maevis

On October 27, 1972, ground was broken for the first section of the Second Avenue Subway, a two track underground rail system that was to extend from the south end of Manhattan at Broad Street, north to the Harlem River at 126th Street, a distance of eight miles. This ground breaking was the culmination of 67 years of planning for an east side subway in Manhattan. Following the successful opening of New York City's first subway on October 1904 there was a mass planning for additional subways throughout the City. In 1905 approval was requested of the Board of Estimate for a First Avenue route and Third Avenue route. The Third Avenue route was approved but when action was not taken to start construction, the approval in accordance with the conditions under which it was given was withdrawn. Further reports and plans for an east side subway, usually to be constructed on Third Avenue, were issued in 1920, in 1922, in 1924, etc. Those of us who had worked on the Sixth and Eighth Avenue subways in the thirites and early forties left to join the armed services of World War II in the expectation that we would return and start work on designing and constructing that east side subway. The reason that much of the thrust in those years was to construct on Third Avenue was that there was a Third Avenue "EL" and business interests of the City were in favor of its demolition. This demolition was accomplished in 1955 so one of the incentives to construct on Third Avenue was removed; but an east side subway was always part of the master plan of the City.

Jan 1, 1976

By R. P. Benson, D. H. MacDonald, D. R. McCreath

1 - INTRODUCTION The Canadian Shield is well known as being among the older exposed areas of the earth's surface. Except for local zones, its extent from the Arctic to central North America is characterized by strong and durable crystalline rocks. It is generally regarded as highly competent for tunnelling and underground excavation and, as a result, many openings are excavated in it with minimal temporary support. If hydraulic efficiency is not a factor, tunnels do not usually require continuous concrete linings. A high percentage of the crystalline rocks of the Shield are of metamorphic origin and as such one of the dominant characteristics is their foliation. Zones of sheared or faulted rock are common in the Canadian Shield, particularly in association with foliation. These zones may be created during the late stages of the metamorphic process, leaving shear zones as an integral feature of foliated rock. As foliation is a preferred direction of weakness, deformation and rupture during subsequent tectonism may also create parallel shear zones. These "foliation shear zones", as described by Deere (1973), are an adverse feature of the otherwise durable rocks of the Canadian Shield. The zones may range from faults of major proportions to seams only a fraction of an inch thick. If fault gouge or alteration products exist in the zone the strength of the rock mass may be great1y reduced. As foliation is usually continuous, large unstable wedges of rock may be created if the opening is subparallel to the foliation. The effect on the construction of underground openings in terms of excavations, support and scheduling can be significant.

Jan 1, 1974

By D. D. Murphy

The Bureau of Mines has studied the mechanism of shear-flocculation of silica with stearic acid. At pH 6 and 12, shear-flocculation of silica was not observed with up to 10-4M (5 lb/st) stearic acid. However, in the presence of 0.1 M NaCl at pH 6, shear-flocculation was observed at stearic acid concentrations 10-4 M (5 lb/st). Adsorption of stearic acid on silica was studied using stearic acids spin-labelled with a doxyl group. The presence of the spin-labelling group did not greatly affect the shear-flocculation properties of stearic acid. Adsorption of labelled stearic acid on silica was measured as a function of surfactant concentration with electron paramagnetic resonance (EPR) spectroscopy and gas chromatography (GC). The GC results indicate the stearic acid was predominately adsorbed on the surface at concentrations above 10-4 M. From the EPR spectra, the formation of aggregates of stearic acid was apparent at concentrations of approximately 10-414 (5 lb/st). The results are discussed in terms of a possible mechanism for shear-flocculation.

Jan 1, 1993

By M. E. Smith

Chile is the world's largest copper producer and as such sets the standard of practice in copper SX/EW design. The authors summarize the liner systems used at many of Chile's major copper producers both operating and planned. The evolution in the state of the art is also discussed, considering both economic factors and Chile's burgeoning environmentalism.

Jan 1, 1994

By Ingo Kaundinya

"INTRODUCTION Tunnels are important elements of the German federal road network which have to cope with an increasing traffic load especially of heavy goods vehicles. In order to ensure a high availability and safety level for these key infrastructures, big efforts are required by owners and operators in order to keep all infrastructures up to date. This mainly relates to current European regulations regarding tunnel safety (Directive 2004/54/EG) [1] and their national implementation, which must be fulfilled by many existing tunnels. In this context the German Federal Government spends more than 1.1 billion € for the structural and operational retrofitting of more than 120 existing road tunnels. As many of these projects have recently been finished or are still under progress, experiences and best practices could be reported. After the description of current requirements in national standards regarding structural fire protection, the paper gives an example for an upgrade of a tunnel’s fire protection by installing an additional fire protection system, which is a quite costly measure. Another possibility to fulfill current requirements regarding structural fire protection could be the numerical proof of sufficient bearing capacity of a structure. The influence of different fire loads and fire durations on the bearing capacity of typical road tunnel structures have been investigated in a research project funded by the German Federal Ministry of Transport (BMVI) and coordinated by the Federal Highway Research Institute (BASt). The results of this research project have been used to define a procedure how to investigate existing tunnels regarding structural fire protection. Finally, the research results have also been the basis for a current update of national standards for tunnel construction. REQUIREMENTS REGARDING STRUCTURAL FIRE PROTECTION The structural fire protection design of road tunnels is usually based on temperature-time curves of exposure to fire, for simplicity called ""fire curves"". The fire development after fire growth is illustrated with fire curves. Fire curves can be subdivided into a heating-up phase, a fully developed fire phase, and if applicable, into a cooling-off phase (cf. Figure 1). During the fully developed fire, the fire remains at a certain temperature level."

Jan 1, 2016

By Sadatoshi Ohmori, Simin Zhai, Devini Abeyawardena

A road tunnel is planned to be constructed in soft, high overburden ground of around 600 m in Japan by using the center drift advancing method. The dodging effect and early ring closure of the center drift were expected to reduce the displacement and deformation of tunnel and promote safe construction. The measurement result during construction was analyzed and those effects, which the displacement and deformation after the widening excavation decreased and its effect increased as the center drift radius increased, were confirmed by numerical analysis. Also, the effect of the early closure of center drift after widening excavation did not have much effect.

Jun 23, 2024

By Richard C. Marshall

The heightened concern over the environment which has developed in recent years has caused activities on National Forest lands to come under more intense public scrutiny. This has been especially true for activities oriented toward the production of commodities. Cattle grazing, mining, timber harvesting, and oil and gas leasing and drilling have all been increasingly subject to appeal and litigation. As a result, environmental analyses being conducted by the Forest Service have become more comprehensive, and measures to reduce or eliminate adverse impacts on resources have been given more attention. The costs of such environmental mitigation measures can be significant even when viewed in the context of the millions of dollars a company may spend, for example, to develop a mine. Using the Montanore Project in northwestern Montana as a case study, this paper examines the costs of alleviating some of the detrimental effects which may occur as a result of a mining operation. Although many of the general issues that have been raised about Montanore are common to other mineral projects, the scale of the project, as well as the fact that the ore body is within a wilderness area, the site is in grizzly bear habitat, and the surface waters are considered to be pristine, all combine to make Montanore particularly challenging from an environ- mental standpoint. Much of the information which follows is contained in the most recent version of the Draft Environmental Impact Statement (DEIS) which is scheduled to be published in several weeks. Based on agency and public comments, some of the information presented in the paper will change before the Final Environmental Impact Statement is issued in 1991.

Jan 1, 1991

By M. L. Matt

The Pittsburgh Safety and Health Technology Center of the Mine Safety and Health Administration has developed the Mine Emergency Responsiveness Development (MERD) program to improve the reaction and response of mine personnel in mine emergency situations. The MERD program simulates problems that may be encountered in underground mine fires, underground mine explosions or surface mine accidents. Since its inception in 1982, the MERD program has been presented to MSHA, Industry, Labor and State Government Personnel. The program is extremely versatile and is easily adapted to suit various training requirements. It gives the participants the opportunity to experience some of the emotions, frustrations and successes of a mine emergency in a controlled environment without having to be involved in one. Past participants have indicated that this training has better prepared them in actual emergency situations through increased awareness and advanced preparation of plans and resources. In 1992, a Mine Simulation Laboratory, which simulates a coal mine and metal/nonmetal mine, was built to improve training for mine emergencies and prevention and fighting of mine fires. This facility has been included in the MERD Program to provide realistic and practical training for mine rescue teams and MERD participants in advanced mine emergency operations. This paper presents an overview of the MERD program.

Jan 1, 1993

By R. L. Eppley

The Blacklick Creek Watershed Association was awarded a $158,000 Growing Greener grant from the Pennsylvania Department of Environmental Protection in 2002 for the design and construction of a sulfate reducing bioreactor (SRBR) cell to treat acidic discharge from the Judy 14 abandoned underground coal mine near Indiana, PA. The vertical flow SRBR was designed to treat 38 liters per minute of MIW containing elevated concentrations of aluminum and iron. Other treatment systems at this site plugged due to aluminum precipitates; this problem did not occur in the SRBR. The bioreactor has been periodically overloaded with flows up to six times the design rate. To date, the only maintenance performed on the unit has been the addition of hay to the surface of the unit in response to less than expected performance. The periodic hay additions appear to have restored the SRBR to nearly post-construction levels. Since construction, the SRBR has treated about 136,000 cubic meters (36 million US gallons) of MIW.

Jan 1, 2010

By Hongjie Yu, Rakshith Shetty, Claudio Cimiotti, Nick Karlin, Mike Mooney, Vitaly Proshchenko, Matt Kendall

This paper documents an effort to explain cutterhead torque behavior observed during slurry pressure balance TBM tunneling through soft ground on the Los Angeles Clearwater project. AI machine learning and mechanics model-based learning was used to characterize cutterhead torque behavior including the TBM operating and ground parameters that influence cutterhead torque. Also, key parameters were from the slurry circuit data, including fines content, in-situ density, pore water fraction and solids content were included. The paper details what was learned using these new data-driven approaches as well as limitations with AI machine learning.

Jun 23, 2024

The strength of anchorage of various types of roof bolts in permafrost depends on the types of rock in which they are installed. Variation in the mine thermal regime results in weakening of the roof and walls, and at times total loss of ice cement bonds takes place in the surrounding rockmass. In mines with positive ventilation air temperature, the wedge or expansion types of bolts may become weakened due to the transfer of heat into the anchorage through the metal rod and subsequent thawing of rocks. Effective operation and evaluation of roof bolt systems for mine workings in permafrost require predictions of the dynamics of wall thawing by warm ventilation air. This paper presents an analysis of the temperature distribution in the frozen host ground surrounding roof bolts, the area of interest being the vicinity of the anchors for point anchored bolt and the entire length for split set bolt

Jan 1, 1994

By Stanley A. Bunk, Desmond J. Bruyns

The purpose of roasting gold ores is to release for extraction, typically by cyanidation, the small particles of gold which are surrounded by refractory stone. The roasting simply opens up passages for the penetration of solution into the interior of the ore particles. This is accomplished by the removal by volatilization or formation of volatile oxides of certain constituents such as sulfur, arsenic or antimony. Temperature is an important parameter. High temperatures tend to form a dense iron particle rather than a "spongy" calcine. The dense iron particles result in lower gold recoveries. High temperature can cause melting of some components which also results in gold encapsulation. Roasting of refractory gold ore concentrates has been practiced for decades. Multiple hearth, rotary kiln and muffle reactors were first used for roasting. Fluid bed roasting provided a low capital cost, low maintenance technology with better process control and soon became the favored technology. The first fluid bed concentrate roasters were commissioned in the late 1940's. Early fluid beds were "bubbling" type. Environmental considerations did not significantly impact on the design. Feedstocks were highly exothermic and reaction rates were relatively rapid. Roasting today must compete with other technologies for treatment of refractory ores. Ore bodies which are not

Jan 1, 1993

By M. Deutsch, E. González, M. Williams

"There is uncertainty in ultimate pit limits due to geologic variation and unpredictable economic landscapes. In this work we show how this uncertainty affects the ultimate pit and how it can be analyzed to improve the mine planning process. A stochastic framework using geostatistical simulation and parametric analysis is used to model the effects of geologic and economic variation on ultimate pit limits and overall project economics. This analysis is made possible by a new, highly efficient pit optimization implementation which can be automated and set up to calculate ultimate pits for hundreds of different scenarios in a matter of hours. Quantifying ultimate pit uncertainty early in the mine planning process allows mining engineers to make informed decisions regarding infrastructure placement, and to mitigate the possibility of incurring substantial costs relocating critical mine facilities. INTRODUCTION The mining industry is increasingly concerned with the effects of risk and uncertainty. Uncertain prices, unpredictable global markets, and unknown foreign exchange rates can alter the economic viability of a mining project in substantial ways. This economic uncertainty is compounded by geologic uncertainty. The extent and quality of any given deposit cannot be fully measured and is not known before consequential decisions must be made. These two sources of uncertainty are responsible for the majority of deviation between what happens during operation and what was initially planned. Understanding and explicitly quantifying this uncertainty will lead to better decision making and allow mining engineers and investors to be aware of what may occur. It is unrealistic to believe that one model, estimated from sparse measurements, is enough to capture both geologic and economic uncertainty and allow for optimal decisions. The entire breadth of uncertainty should be considered, as both upside and downside risks have large impacts on the investment potential and operational efficiency of mining projects. The workflow presented here uses Monte Carlo simulation and parametric analysis together to explicitly analyze the breadth of geologic and economic uncertainty as it applies to ultimate pit calculation and long range mine planning."

Jan 1, 2015

By John Thella, Edward McNew, Christina Thella, Mends Emmanuel, Pengbo Chu

Ore sorting is an emerging technology in mineral processing that can produce a significant impact on the total mining and processing economics. The technology is capable of preconcentrating an ore based on differences in the mineralogical characteristics, which can include color, brightness, transparency, size, shape, density or near-infrared response. The current practice of conducting an ore sorting test typically requires large amounts of materials to be sent to a commercial testing facility, which is expensive and time-consuming. Here, we present a novel method to simulate commercial ore sorting on a laboratory scale using a rare earth ore.

Jan 1, 2025

When solid pillar is not left to separate different mining levels in underground mine with high dip angle deposit, waste rock in the backfilled stope could be a safety hazard to future mining activities on levels above or below the backfill. Different backfill methods can be used to eliminate this hazard according to the deposit shape and mining method. Building concrete pillar in ore drift of each mining level is one of them. Concrete pillar had been constructed in underground mines based on operational experience. Little design literature and pillar performance data can be found. At Great Basin Gold Hollister Mine, over two thousand feet of concrete pillar had been constructed. The project started with engineering design which combined civil engineering concrete design and the specialties of underground construction. Time Domain Reflectometry technique was installed to monitor the pillar movement and concrete cylinder samples were collected and tested for quality control. Engineering design, underground construction, quality control and concrete pillar monitoring, as well as precious concrete mixing data from years of experience are fully covered in this paper to give a general frame of concrete pillar method.

Jan 1, 2010

By Ehsan Alavi, Brian Hagan, Colin LaVassar, Glen Frank, Derek Dugan, Rick Capka, Lisa Mori

"Tunnel face instability is one of the most common issues in EPB tunneling. The evaluation of an ideal face support pressure is a critical element in the design and construction phases of EPB tunneling. In this study, measured tunnel face pressures in three EPB tunneling projects (University Link U230 and U220 projects and the Northgate Link Extension N125 Project) for Sound Transit in Seattle, WA are compared with the calculated analytical methods. This comparison shows that the analytical methods generally overestimate the required tunnel face support. The best practice for managing the face pressure in EPB tunneling operation is discussed based on the experience gained through these projects. Furthermore, the algorithm that is developed for identifying ground loss in these projects is addressed. INTRODUCTION Earth pressure balanced tunneling relies on using muck within the chamber to support the face. Muck is pressurized by controlling the advance rate of the tunnel boring machine and the speed of the screw conveyor. Target face pressure is typically calculated by using the geotechnical assumptions in the geotechnical baseline report. The concept behind EPB tunneling is that the application of sufficient face support pressure will prevent tunnel face instability and the resultant over excavation. Tunnel face instabilities caused by a lack of sufficient face support can lead to ground loss and surface settlement (Anagnostou & Kovári 1996, Kirsch 2010). A certain support pressure must be achieved to counteract water and earth pressure with an adequate factor of safety. While the water pressure can be predicted accurately, the determination of the resultant earth pressure on the face is less precise. This becomes manifested in the relatively high partial safety factors on the earth pressure."

Jan 1, 2016

By R. C. Berry

The Environmental Impact Statement (EIS) has become a routine requirement for mining operations on federal lands. A similar document is being required in developing countries. Baseline studies are needed prior to writing an EIS and these studies involve surface water, groundwater, air quality, and wildlife/ native plant evaluations. The required baseline hydrology and geochemical studies are often the most expensive and lengthy evaluations. This paper summarizes the hydrology and geochemical baseline studies required for .An EIS and presents suggested methods to expedite these studies and to shorten the time and the cost to complete the studies and the EIS.

Jan 1, 1999