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By Arun Patel, Diane Hirsch, Pamela Moran

The Metropolitan Washington Airports Authority (Authority) has undertaken a tremendous expansion of Washington Dulles International Airport in Fairfax, Virginia, including upgrading passenger transportation between concourses. The first stage of this expansion envisioned a shallow cut-and-cover pedestrian tunnel between the Main Terminal and Concourse B with associated vertical circulation structures. At the beginning of the design contract, the Authority’s consulting team of Earth Tech, formerly Kaiser Engineers, and the Dr. G. Sauer Corporation compared the cost and disruption of constructing the tunnel as a cut-and-cover structure to mining the tunnel using the New Austrian Tunneling Method (NATM). Upon review, the Authority endorsed the latter method.

Jan 1, 2003

By Randall C. Divito, Craig R. Eckdahl, Bruce D. Wagener, Joseph Klejwa

The existing Central City Tunnel was built primarily in the 1930s with a small portion as old as the 1880s. It conveys stormwater in downtown Minneapolis. It is a 4,400-ft long tunnel located 80 feet underground. The Central City Tunnel has experienced surcharging and surface overflows during heavy rainfall events. This paper presents the details of tunnel and shaft design for the new Central City Parallel Tunnel to mitigate the overflows. The design considered hydraulics and geotechnical engineering for the structural geologic conditions including the weak Saint Peter Sandstone and overlying strong Platteville Limestone. Ground conditions resulted in tunnel designs including large flat-back box tunnels and unique cathedral-shaped tunnel sections.

Jun 13, 2023

By J. E. Litz

The hydrometallurgy review did not arrive in time for publication in the May issue. 1992 was not a banner year for hydrometallurgical installations or new hydrometallurgical developments. Installation of copper solvent extraction/electrowinning circuits were under construction or began operation in Nevada (Yerrington ), Arizona (SilverBell), Chile (Copiapo and Escondida), Peru (Toquepala and Cuayone) and Australia (Girilambone). These installations will produce more than 100 kt/a (110,000 stpy) of cathode copper. Several new heap leach gold facilities using conventional technologies were announced or were put into operation. New technologies undergoing widespread testing include biological oxidation of low-grade ores in a heap leach mode and evaluation of new agglomerating agents.

Jan 1, 1993

By Arnold E. Lamm

The degree of economic, progress of a nation is measured by its possession and use of energy, sources. The future of coal in the West hinges on its ability to participate and grow in the energy market. A source of energy is, in the long run, only as good as the ability of the industry to develop its reserves economically. The economic development of the tremendous coal reserves, literally hundreds of billions of tons of coal in the States of Colorado, Utah, Wyoming, Montana, New Mexico, and Arizona, poses a very real question in the light of the known mining technology of our day. Basically in America today, coal is mined from the earth either by the strip mine or underground mine method; in the West, the large long-term, contracts now in force with utilities are mostly from coal mines utilizing the strip mine method. However, the preponderance of the known coal reserves of the West are located deep underground and will have to be mined by the various; underground mining processes. The problems encountered in the West with regard to underground mining vary from state to state but, on the whole, do not present what might be considered a miner's bonanza. I do not mean to' infer that the underground coal of the West is unmineable, but I do want to emphasize that the tremendous reserve figures do not present a true picture in the light of present day technology.

Jan 1, 1965

By Donald J. Donahue

Ladies and Gentlemen: As we begin these three crowded days of technical and economic discussion of problems faced by mining and metallurgical engineers, it seems appropriate at this Keynote Session to consider the future of this industry from which we derive our livelihood, It is also appropriate at this international meeting to view our industry on a world-wide basis. First, let us assess the world's future needs for minerals - the needs which it is our industry's task to meet. Next, let us look at what supplies of minerals may be available to meet those needs. I will speak of this first in terms of the physical availabilities of minerals. Finally, we can consider some of the social or institutional factors which will condition the world's mining industry as it goes about its task of discovering, developing, producing, and delivering the minerals needed to meet the world's demands. Let me give you a foretaste of my conclusions. First, future world demands upon our industry will be enormous, eclipsing anything that we have known up to this point. Second, there is strong evidence that our earth's crust contains a sufficient physical quantity and variety of minerals to meet forthcoming needs for as long a period ahead as one can envisage.

Jan 1, 1974

By Robert R. Dorfler

AMPS[. has completed a rationed grinding ball test in a 2.93 m x 2.93 m ball mill at Climax Molybdenum Company. The test consisted of purging the ball distribution formed by charging 100%, 76 mm carbon steel balls with a distribution formed by charging 50% 76 mm and 20% 51 mm alloy steel balls. The resulting change in ball surface area yielded improvements in both tons ground and fineness of grind with a significant reduction in total ball consumption. This paper summarizes preliminary studies leading to the plant test, grinding efficiency results, and future plans to optimize the ball charge.

Jan 1, 1981

By Ehsan Alavi, Sanjeer Yogendran, Savreet Singh

The Don River & Central Waterfront Coxwell Sanitary Bypass Tunnel Project in Toronto extends approximately 10.5 km from Ashbridges Bay Treatment Plant west under Lake Shore Boulevard, north under Bayview Avenue and east through the Don River park area to the Coxwell Ravine Park. This project includes the installation of five intake shafts connected by 10.5 km of 6.3 m internal diameter tunnel and eleven drop shafts and vent shafts, connected to the tunnel by a series of adits. During the excavation of one of five intake shafts (20 m in diameter and 52 m deep), significant volumes of free phase oil and hydrocarbons were encountered. Due to the heavy inflows of the contaminants, excavation was stopped at the transition depth. The initial support of excavation needed to be redesigned, shaft had to be backfilled with CDF and installation of deeper secant piles are in progress to cut off contaminants. This paper outlines the initial plan for excavation as well as the design changes to the plan. The current status of the shaft excavation and lessons learned will be discussed.

Jun 13, 2021

By André Vervoort

After the systematic closure of Europe’s coalfields in the late twentieth century, the emphasis is now clearly on industry’s environmental legacy. One aspect of the latter is the longterm surface movement above abandoned coal mines. The analysis of satellite data shows that the subsidence lasts longer than generally assumed. However, a few years after the flooding of the abandoned underground coal mines, a new phenomenon was observed, i.e., the direction of the surface movement was reversed. The phase of upsidence has already lasted for several decades, and only future measurements will tell how long it continues. A key conclusion is that the regions with maximum subsidence do not necessarily correspond to the greatest upsidence. In other words, buildings and infrastructure are subjected to a different loading from this upsidence than during the subsidence phase. The longterm surface movements have an impact on vulnerable structures in the densely populated regions of the former deep coal mining areas in Europe. These movements create additional damage. This new knowledge is also relevant for mines that are still in operation or future mines that are planned.

Feb 1, 2024

Mineral processing plant operators are faced with the necessity to choose between many different possibilities for plant improvement. Only a few such possibilities, however, can be tested on the industrial site. Steady-state simulators make it possible to assess the effects of several different flowsheet modifications in a few days, thus helping the process engineer to make his choice implement the solution that seems the most appropriate and check it. The example described here is the crushing and grinding circuit of the Shila Gold Mine, jointly owned by CEDIMIN SA and BUENAVENTURA SA, in Peru. Several possible modifications for the purpose of increasing capacity have been simulated and the results assessed in terms of technical quality, investment costs and energy consumption. The best solution indicated by the USIM PAC simulator was implemented and gave a 20% increase in capacity with a pay-back time of two months.

Jan 1, 1993

By Ehsan Alavi, Eren Kusdogan

The City of Toronto’s Coxwell Bypass Tunnel is currently being constructed by North Tunnel Constructors ULC, a joint venture of Jay Dee Canada, C&M McNally Tunnel Constructors and Michels Canada. This project includes construction of approximately 10.5 km of 6.3 meter finished diameter rock tunnel, five 20 meter diameter storage shafts and eleven tunnel connection drop shafts, along with associated deaeration and adit tunnels. This paper describes progress on the project to date and reviews the risk mitigation measures utilized on the project to move the project forward through tough geological conditions during shaft excavation and tunneling phase of the project.

Jun 13, 2023

By W.J. Atkinson

The first recorded discovery of diamonds in Australia was in 1851 from New South Wales. Subsequent prospecting has shown alluvial occurrences of diamond to be relatively widespread through much of the Tasman Fold Belts of Eastern Australia and production to date is estimated to be some 500 000 carats from a number of 'small alluvial fields. Despite extensive exploration though, no primary rock source carrying significant diamond contents has ever been confirmed in Eastern Australia. Conversely, diamond exploration of the older Western and Central Cratons of Australia over the past 30 years has discovered 12 fields containing 360 kimberlites, lamproites and lamprophyric volcanic pipes, dykes and other intrusives, of which 180 have been confirmed to be diamondiferous. Only one pipe however, the 1200 Ma high grade Argyle lamproite and associated near-by alluvials, has proved to be economically exploitable with current annual production of 40 million carats valued at approximately US$400 million. Production from the open-pit will be sustainable until at least 2003. This paper briefly summarizes the history of diamond discovery in Australia, principal diamondiferous provinces and deposits, current exploration activities and the potential for future discoveries.

Jan 1, 1995

By Jacques B. Wertz

However excellent the geologic map of an area is, it can only show what is exposed on the ground. It cannot and should not generalize the information nor complete the picture by inference: this is left to the examiner. Consequently, it becomes justified for him to use all expressions of geologic structure in order to gain an additional dimension in geologic interpretation, and particularly so in mineral exploration. In previous studies related to Arizona, the known faults were the starting points and a host of interpolated, supporting geologic factors described in earlier publications ascertained the presence of a series of structural trends and lineaments found to be rather continuous and persistent, even though unsubstantiated by geologic maps. In present studies pertaining to the humid environment, with the same aim of seeking major structural trends and lineaments, the starting points are morphologic expressions such as straight lakes and straight segments of rivers, among others, because there generally is not enough geology available. An example is given herewith for an area that straddles the International Border, north of Spokane. In both semi-arid and humid environments, one observes that mineral deposits quite often occur close to the intersection of a major fracture or lineament with some secondary trend.

Jan 1, 1971

By Jr. Garnar

Heavy mineral mining has been a relatively small but important Florida industry for over sixty years. Geology of the Florida heavy mineral deposits is similar. Each formed along active coastlines after which the titanium minerals were upgraded in TiO2 by post depositional oxidation and leaching of the iron. There are four heavy mineral plants currently Operating in Florida. Ore is mined by dredges and the heavy minerals concentrated by gravity separation. The heavy mineral concentrates are further processed with high tension and electromagnetic separators to Produce titanium mineral concentrates for TiO2 pigment manufacturing plants. Zircon sand is produced as a co-product at all of the Florida plants. Staurolite is produced by Du Pont and Titanium Enterprises. Du Pont also markets a kyanite-sillimanite product. (Monazite is produced by Humphreys and Titanium Enterprises). Reclamation of mined-out land is an important part of heavy mineral mining. At the Du Pont plants soil is removed ahead of the dredge and placed over the quartz sand tailings. Grass is planted after fertilizing. A year later the land is fertilized again and pine trees planted. Most of the heavy mineral deposits now being mined will be nearly exhausted by the end of the century. New deposits to be mined in the 21st century will probably be smaller and lower grade than those now being mined. Advances in mineral processing technology will have to be made to allow these lower grade deposits to be mined economically.

Jan 1, 1978

By D. Lelinski

Air-sparged hydrocyclone (ASH) flotation is one of the new promising technologies. Numerous applications have been successfully tested since its conception; nevertheless, research and development efforts have continued to provide for further improvements with respect to operating conditions and design considerations. Results from experimental studies on bubbles generation in the ASH system are presented in this paper. Bubble size distributions generated during ASH operation have been determined using a high-speed photographic technique. The influence of many factors including surfactant concentration, water flowrate, and porous tube pore size has been studied. Test results indicate that these process variables have a profound effect on the bubble size distribution. With an increase in surfactant concentration or water flowrate (shear field) the bubble size distributions become narrower and shift toward smaller average bubble diameters. However, the influence of pore size is more complicated. Depending on the experimental conditions the average bubble size was found to range from about 100 to 300 microns in diameter.

Jan 1, 1995

By NICHOLAS BELLUSCI, D. Erik Spiller, Patrick R. Taylor, VICTOR BRAMAN

Approximately 30% of the world’s production of soda ash comes from mining and processing of naturally occurring deposits of sodium carbonate containing species. Of these deposits, the largest and most profitable have been the trona beds found near Green River, Wyoming. Processing of trona ores is water-energy intensive, particularly due to unit operations of calcination, dissolution, and evaporative crystallization to wield a high-quality dense soda ash product and reject the insoluble gangue species, primarily in the form of oil shale. However, it is speculated that the glass-manufacturing industry, the largest consumer of soda ash, may be able to use a product of a lower grade and consistent level of the insoluble constituents. Thus, pre-concentration of trona ore was investigated using sensor-based sorting, to produce a beneficiated trona stream that would be fed to calcination. The study encompassed preparation of a run-of-mine (ROM) Green River ore sample, selection of 25–75-mm-sized specimens, imaging of the specimens by x-ray transmission (XRT), color, and laser-induced fluorescence (LIF)-based sensors, insoluble analysis of the specimens, and a bench-scale sorting test. Results of the study established that a correlation between the color of the individual ore particles and their insoluble content existed and that a surface detection-based sensor, particularly LIF, was apparently more suitable than XRT to produce a beneficiated trona stream. The bench-scale sorting test demonstrated that a 65% separation efficiency and a 70% recovery of trona could be achieved.

Aug 9, 2022

By M. L. W. Tuttle, B. R. Berger

Our study focuses on the geology, hydrology, and geochemistry of a variety of molybdenum (Mo) porphyry systems. The systems are either high fluorine, granite, Climax-type, systems (e.g. Mount Emmons/Redwell Mo deposit, Colorado and Questa Mo deposit, New Mexico) or low fluorine granodiorite systems (e.g. Buckingham Stockwork Mo deposit, Battle Mountain, Nevada and Cannivan Gulch Mo deposit, Montana). The water quality of streams, natural springs, mine discharge, and ground water from drill holes were assessed in the region of these deposits. The ultimate goal of our study is to understand the environ-mental behavior of these Mo porphyry systems in the context of geologic setting, hydrologic regime, and climate.

Jan 1, 2004

By Kurt Wiener

A major process control system is in some ways like a complex organism. The extremities, (that is, field instruments) are exposed to many hazards and suffer malfunctions of relatively minor and repetitive nature. Here I equate a stuck valve or dead transmitter with a skin abrasion or cut. The maintenance and repair of the extremities can be done by technicians with basic but thorough knowledge of relatively few problems and their solutions. Here I equate with administering Band-Aids and aspirin. On the other extreme, when the master control device (such as a computer) fails, one does not attempt home remedies. A "brain" specialist is called in. It is, however, crucial that the patient be able to clearly describe his symptoms. Getting down to the case at hand, a complex system consisting of field instruments, instrument racks, interface equipment, and perhaps a computer, may require maintenance at all levels. At the field equipment end where physical damage, corrosive atmospheres, reconfiguration, and routine calibration checks are common, the customer has the opportunity to develop a competent staff of maintenance people. The relatively high maintenance activity assures competence through repetition.

Jan 1, 1980

By S. Amirshenava, S. Nadimi

"Premature and unplanned mine closure can result in significant adverse impacts on the environment and community and need to be managed appropriately. Risk management techniques can reduce the negative impacts and risks of early mine closure. Risk Assessment 3D Model, is an efficient tool to quantify risk. The aim of this paper is to identify the mine closure risks in Choghart iron ore mine, and calculate the overall mine closure risk level. The result shows that 51.4% of assessed risks have low risk level and the overall risk level of early mine closure is low. Keywords: mine closure, risk assessment 3D model, Choghart iron ore mine INTRODUCTION The modern mining life-cycle can be divided into three main stages; exploration, mining (opening and production) and post mining (mine closure, and reclamation). Mine closure is the critical component of the modern mining life-cycle and it refers to the period of time when the operational stage of a mine has permanently ceases (Heikkinen et al, 2008). Planned closure occurs due to the depletion of ore reserves, but sometimes it is premature. Laurance (2006) shows that only 25% of mine closure in the past 30 years was due to resource depletion and in 75% of the cases the mines were closed for the other reasons. Ghanbari et al (2010) demonstrated that 48.6 % of copper mine closure in the past 100 years was due to resource depletion and 51.4 % of copper mines have been closed due to other reasons. The main reasons of premature mine closure are as follow (Laurance, 2006; Ghanbari et al, 2010; Maiti, 2013): • Economic, (low commodity prices or high costs) • Geological, (over-estimation of grade and tonnage) • Geotechnical (adverse geotechnical conditions) • Technical (equipment failure) • Regulatory, due to safety or environmental breaches • Social or community pressures • Closure of downstream industry or markets • Flooding or inrush Minaei Mobtaker and Osanloo (2013) developed a mine closure prediction model based on the data collected from closed iron ore mines in the past 100 years. They showed that economic factors, exhaustion of ore reserve and geological conditions are the main reasons of iron ore mine closure. They treated mine closure as a decision making problem in order to predict the causes of mine closure, including the uncertainties of some mine plan parameter such as iron ore price, production and consumption."

Jan 1, 2016

By VASU GANGRADE, Marcia Harris, Kumar Vaibhav Raj, Jim Addis, Khaled Mohamed, Snigdha Sarkar

The National Institute for Occupational Safety and Health (NIOSH) conducted a ventilation assessment for a recently established underground room-and-pillar stone mine implementing split-mine ventilation. The primary objective was to examine the impact of the length of the in-place stone stoppings on face ventilation efficiency. These stone stoppings serve to separate the intake and exhaust entries and align with the mining direction. To achieve this, computational fluid dynamics (CFD) modeling was utilized. The appropriate turbulence model was selected, and a mesh convergence analysis was conducted for the CFD model. Following that, the CFD model was validated using the conducted ventilation surveys. Two configurations of in-place stone stoppings, designated as Layout-I and Layout-II, were simulated using the validated CFD models. Layout-I featured a shorter in-place stone stopping, while Layout-II had a longer one. The results obtained from the CFD models demonstrated that the increased length of the in-place stone stopping in Layout-II resulted in a notable enhancement in ventilation efficiency at the advanced faces (last stopping), elevating it from 4% in Layout-I to 8.4% in Layout-II. However, no significant impact of the in-place stopping layouts was observed at other faces. In general, Layout-II exhibited a greater circulation of air at the outby stoppings.

Feb 1, 2024

By David R. Hargis

Large-scale groundwater withdrawals are necessary to depressurize a confined aquifer system allowing the dry open-pit mining of the overlying phosphate ore. The extent of the existing and planned groundwater development led to the establishment by the State of North Carolina of Capacity Use Area No. l. Groundwater use in the Capacity Use Area is regulated by a permitting system. A two-dimensional finite-difference ground- water flow model was developed for North Carolina Phosphate Corporation. The aim of the model is to aid the Corporation in matters relating to permitting by serving as a predictive tool. The model can be used to project regional water level impacts resulting from various scenarios of depressurization pumping.

Jan 1, 1983