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By Richard Crowell, James Gillaspie

A concentrate biooxidation process was successfully demon­strated in the field in a remote part of northwestern Mexico. A 275 tonne (300 st) biooxidation heap was constructed using GeoBiotics' proprietary GEOCOAT™ coated concentrate process. The pyrite/chalcopyrite/sphalerite concentrate was bioox­idized in the heap for 60 days. Cyanide leach recovery of the con­centrate increased from 68% gold recovery at a cyanide consump­tion of 1.6 kg NaCN/g Au (llO lbs/oz) in the as-received concen­trate, to 94% gold recovery at a cyanide consumption of 0.37 kg NaCN/g Au (27 lbs/oz) in the biooxidized concentrate. The heap was constructed at a rate of7 tonnes (7.5 st) concentrate per hour, using typical heap leach equipment and easily scalable methods. Heap operations demonstrated that energy dissipation in the humid summer environment was easily controlled by low pressure aeration and management of solution chemistry and application. Observations of the demonstration heap appear to support the presence of reflux of moisture within the biooxidation heap.

Jan 1, 1998

By Kirk Carlton

The Athabasca tar sands of Alberta are an increasingly important source of crude oil for the North American continent. Published figures indicate estimates of recoverable resources in the tar sands at some 300 billion barrels of synthetic crude of which some 86 billion barrels can be recovered by surface mining techniques. At the present time, two commercial plants are in operation, Great Canadian Oil Sands Limited and Syncrude Canada Ltd. Their present combined capacity is approximately 150,000 barrels per day. Some of the factors which will make this oil expensive will be noted here. The location of the present producing plants is 500 kilometres north of Edmonton at an elevation of approximately 320 metres. Recorded temperatures range from +38 to -55 degrees Celsius. Wind velocities are not high but the chill factor with even a slight breeze and minus 40 degrees is very uncomfortable.

Jan 1, 1979

By Peter Zhang, Todd Minoski, Gabriel Esterhuizen, Jack Trackemas, Berk Tulu, Morgan Sears

Roof stability in the belt entry is critical for safe and continuous production of coal during longwall mining. Previous studies of roof falls that occurred in belt entries have shown that the roof falls were largely associated with high in situ and longwall-induced horizontal stresses [1,2,3,4]. To properly support the roof in a belt entry, it is important to understand how longwall-induced horizontal stress changes can affect roof stability in the belt entry. Monitoring of horizontal stress changes was conducted in the belt entries of two Pittsburgh seam longwall panels oriented unfavorably to the major horizontal stress. Numerical models were also set up to investigate how horizontal stress concentrates and relieves in the belt-entry roof near the face as panel orientation changes. Both measurements and modeling results show that high horizontal stress concentrates in the belt entry roof within about 15 m outby the face. The study demonstrates that longwall-induced differential horizontal stress can be used to evaluate the horizontal stress concentration factors. The horizontal stress concentration factors change with panel orientation, resulting in high stress concentrations at orientations between 20 and 110° and low stress concentrations between 130 and 180°. Roof support strategies are given for the belt entries under the influence of high horizontal stress. For unfavorably oriented panels in weak roof conditions, supplementary support should be installed during development, and cable bolts should be anchored into a stable roof horizon. The bolting pattern should be designed to cover both entry corners and the entry center to prevent potential roof cutters and sagging.

Jan 1, 2023

By Steven R. Wardwell, Gerald G. Stokes

INTRODUCTION A compaction grouting program to control ground loss, and to minimize surface settlement, was developed for the West Tunnel of the Phoenix Storm Drain Tunnels. The West Tunnel was 4,200 m long, 7.56 m in excavated diameter, and was excavated with shallow cover through the central Phoenix business district. The tunnel could not have been successfully excavated without the compaction grouting program. HISTORY After heated political debate over a ten year period, the Arizona Department of Transportation (ADOT) was granted approval to build the Papago Freeway, an extension of Interstate 10, through central Phoenix. To comply with environmental constraints, a portion of the Freeway was depressed, requiring an excavation 10 meters in depth, thus intersecting surface run-off from the northern section of Phoenix. This required that ADOT and Project Design Consultant, Howard, Needles, Tammen & Bergendoff (HNTB) design a drain system to collect run-off and transport it approximately 4 kilometers to the Salt River through the City of Phoenix. Tunnels were chosen for the main discharge conduits because depth and location of the system made cut and cover construction impractical. A contract for construction of the tunnels was awarded to Shank-Artukovich-Ohbayashi (S-A-O) on May 24, 1984.

Jan 1, 1987

By Peter V. Avotins

During last year's AIME meeting in New Orleans, Deepak Malhotra and I were discussing some of the topics that would be presented in this Symposium. It seemed appropriate that along with papers on specific reagent and flocculant types, we should address research management aspects of new product development. This development is a long, arduous task that requires a significant technical and fiscal commitment by the chemical company and potential users. A flow chart depicting the research process is shown in Figure 1. The sequence of events are plotted on an undefined time line. Our experience has shown that it takes 3-5 years to complete a typical reagent development project. A new project starts with an idea of how to do something better. The ideas range from relatively simple product modifications to opportunities created by technological change. An example of this is the use of flocculants in tailings operations to close the water recycle loop. The change was brought about by the need to conserve water and comply with environmental statutes. The result was the development and wide-spread use of synthetic polymers to help in solid-liquid separation. More recently the ups and downs of oil prices have led to development of coal water slurries as an alternative to fuel oil. The slurries contain high levels of chemicals (up to 3%) to insure proper stability and burn characteristics. There are technical changes under way right now that may lead to ideas for other new products. One exciting source of new technology is the ability to manipulate genetic material of microbes to select for specific capabilities. This has evolved by leaps and bounds over the past 5 years. Biologically assisted leaching and removal of wastewater impurities are two possible end uses. I'm sure that there are many others. The ideas can originate anywhere and are often half-baked at first, but to lead to new products they must be refined to provide project definition and eventually a research plan. A chemical ,development project cannot be started without approval to commit the company's resources. The internal selling job is often very difficult. The company must see clear financial benefits in order to launch efforts that may not pay off for many years. It is critical to project the total market, profitability, eventual market share, and timing of introduction of the new product. There is much uncertainty in this and the research manager is often skating on thin ice to retain his credibility. Once we obtain support from upper management, the research team is assembled to start the project. The teams generally consist of organic chemists, research metallurgists, and technicians. They have access to analytical scientists and technicians for surface and analytical chemistry. The projects are often augmented by help from university staff and consultants. This is particularly true where there is a need to develop fundamental understanding of the technology in addition to synthesis of chemicals. The project now proceeds along two lines. First, there is an emphasis on understanding the prior art. Extensive literature and patent searches are undertaken to provide research leads and to keep from "reinventing the wheel" and infringing on someone else's patent. The scientists and technologists are qualified to conduct computer-assisted library searches. This process usually uncovers 80-90% of the relevant information. The remainder is very much harder to get and requires the help of professional library search staff with scientific backgrounds. Along with literature searching, the team begins synthesis of new compounds. These are screened by use of techniques such as microflotation or filtration in a Buchner funnel. The scientists are looking for the direction of response as they modify structural features . Inevitably, a large number of candidates reach the next stage, a laboratory bench test. At this point it is possible to set up a research plan and use project management techniques to monitor progress. The bench tests are conducted in larger equipment, usually requiring 100-1000 grams of test substrate. Typical laboratory flotation tests are run in Denver or Wemco cells.

Jan 1, 1986

By W. M. Ma, Daniel W. H. Su, K. Centofanti, Yi Luo, W. L. Zhong, Syd S. Peng

NTRODUCTION Surface subsidence monitoring is the most effective means for investigating the nature of, and developing the techniques for pre¬dicting the surface movement and deformation process. However, because of imperfection in survey equipment and field practices, the surface movement data collected from field survey are not error-free. Also due to lack of proper numerical techniques for computing surface deformation from the measured surface move¬ment data, a relatively large portion of the subsidence data col¬lected could not provide information other than surface movement. In a paper by Luo and Peng (1992), the sources and magnitude of errors in the measured surface movements using an electronic total station in subsidence survey are discussed. If the errors in the measured surface movement components are left untreated before calculation for deformation indices (i.e., slope, strain and curva¬ture), the errors will be carried over to the deformation indices and enlarged if improper numerical procedures are used in the calcu¬lation. It should be noticed that in protecting structures affected by ground subsidence, accurate surface deformation indices are much more important than surface movement. In order to improve the accuracy of the collected surface movement data and the calcu¬lated deformation indices, a number of numerical procedures are also proposed in the same paper. The proposed techniques include: a data smoothing technique for data pre-processing; and a number of numerical methods and/or procedures for calculating surface deformation indices from the measured surface movement data. DATA SMOOTHING Because of various factors, the measured surface movement data always contain errors, small or large. In order to better utilize the collected data, a data smoothing method is proposed to correct the errors in the measured movement data. The method uses the same concept as the influence function method (e.g., Knothe, 1957) on which many existing subsidence prediction methods are based. The data smoothing method makes necessary corrections on the measured movement for the point of interest according to not only the measured movement at this point but also those at the surrounding points. The contribution of a surrounding point in making the correction for the point of interest is inversely propor¬tional, in exponential form, to the distance between them. The new magnitude of a movement component at the point of interest (Zi*) is calculated by

Jan 1, 1992

By Ethan B. Eilertsen

Titanium solves corrosion, maintenance and environmental problems in many reactor and autoclave applications. Titanium clad construction permits autoclave designers a great deal of flexibility combined with significant cost reduction. Titanium alloys can be selectively applied in specific regions of the autoclave to accommodate local environmental conditions. Resistance to general corrosion, crevice corrosion, abrasion, and ignition conditions can be accomplished selectively and economically. Explosion clad pressure vessel fabrication and performance have been proven through three decades of experience.

Jan 1, 1997

By CAIJUN CHEN, MING ZHANG, ZHENWEI WU, FENG ZHOU, BOQUAN LI, XILIANG ZHANG, ZHOU PU

Traveling grate is a widely used process for iron ore pellet production, but the thermal state of pellets in the drying section is still unclear. In this study, the temperature distribution of the drying section was investigated using computational fluid dynamics (CFD). The results indicate there is a coupling effect in the drying section of a traveling grate. Gas with higher temperature in down-draught drying (DDD) transfers heat to the up-draught drying (UDD) through the gap of the insulation board, and the temperature gradient of the pellet bed changes before reaching the insulation board. The characteristics of pellet bed expected to appear in DDD are displayed in UDD in advance. To verify the model, a contrast experiment was conducted.

By Charles Bruce

Three years ago, at a reception given during the Steel Institute meeting in New York, I heard the remark, "A new formula must be found for foreign investment." This was immediately following the takeover of U. S. Steel's Matilde operation in Bolivia. Recently, at the World Mining Congress in Lima, Peru, the subject of foreign investment was still a lively topic of conversation. The nationalization of the copper mines in Chile and recent trends in the "Third World" have made all but a few extremely wary of investment anywhere other than in the ?stable? countries. Now, the fallibility of this philosophy has been demonstrated in such "stable" countries as Canada, Australia, and Ireland. Yet, nationalization is not new to us. The events in Chile were classified as disastrous to the affected companies, but so were the effects of nationalization to the majors in Bolivia in 1952. Mexicanization of the mining industry in Mexico was considered impractical by many. Now, those who accepted it are finding it to be workable.

Jan 1, 1975

By Robert S. Mayo

My subject today is "Drilling-and-Blasting of Small Rock Tunnels". I am sure that there will be some people, primarily college students but perhaps Consulting Engineers, who will say: "Drilling-and-Blasting? I thought that went out with the invention of the Tunnel Boring Machine". A few years ago I talked to Dick Robbins and he told me that they did not try to sell a "Robbin's Mole" unless the tunnel was two miles long. For easy calculations I use 10,000-ft. (3km) A Mole today costs about $2 million which works out to $200 per lineal foot. This is "front money". You cannot place the order unless you are the uncontested low-bidder and then you must wait at least six months for delivery. Of course you can use that time to square up your portals, ready to turn-the-eye, or maybe you have shafts to sink to reach the tunnel grade. But this is "dead-time" and it is a heck of a feeling to have a job and cannot get started on it until you get the Mole. I do not have the American figures on lengths of tunnels but there was an article a few years ago in a British magazine: NEW CIVIL ENGINEER, on this subject. This stated that 75% of the jobs in Britain which were bid were for small tunnels, 10-ft x 10-ft (3m x 3m) or smaller, and that they were less than 5,000-ft (1.5km) in length. This does not mean that 75% of the footage in Britain was less than 10-ft in diameter. It means that 75% of the jobs being bid were less than a mile in length. From my experience in the U.S. I believe that we have substantially the same ratio: so many of the jobs with which I was associated were short, 1,000-ft, 2,000-ft and sometimes 3,000-ft and the bores

Jan 1, 1981

By C. F. Curry

In the early 1940's Humphreys Mining Company in Florida pioneered heavy mineral mining with a dredge in the United States, In 1948 Du Pont, in conjunction with Humphreys, opened their first of two mining operations recovering a titanium dioxide product in Florida. Later on in 1952 Du Pont opened their second plant, both of which used a cutterhead suction type of operation. This process is also used in heavy mineral mining in Australia and Africa. In 1957 ASARCO started prospecting in New Jersey. Test borings indicated a large deposit of ilmenite bearing heavy mineral sands had been deposited and concentrated in an area near Lakehurst in central New Jersey. Humphreys Mining Company was contacted about the possibility of mining the ASARCO New Jersey property in much the same way as Du Pont and themselves were doing in Florida. An extensive study was made to determine the economic feasibility of mining the ASARCO property. During this study, extensive test drilling and samples for a pilot plant were taken.

Jan 1, 1975

By Q. Lin, D. Z. Wang

Molecular design plays an important role in development of new flotation reagents. Group electronegativity calculation is a main method of molecular design. It is commonly used in calculating the hydrophilic-hydrophobic balance of reagents, particularly in designing chain length of flotation reagents for located minerals. But there is a limit to group electronegativity method. The method can only apply to those of [Ø]known straight-chain compounds ([Ø] is the hydrophobic energy of each -CH2- , determined by experiment). In this Paper, we propose another new calculation method: fragment method of flotation reagent. The method could be used as a supplement of group electronegativity method to design and calculate flotation reagents without any limitation. With the fragment method, we can calculate the hydrophilic-hydrophobic performance of any known or unknown reagents including those complicate structure compounds such as cyclic, branch, heterocyclic and so on by summing the appropriate structural elements (fragment). The principle, calculation stages and some results of designing new-type flotation reagents by fragment method are presented in this paper.

Jan 1, 1995

By James A. Nunn

Location Xiaolangdi is located in the Henan province of the People’s Republic of China. The distance between Xiaolangdi and the capital of Henan, Zhengzhou, is about200 km. Xiaolangdi is located on the Yellow River at the end of its big characteristic knee. It can be easily found on the map by locating Luoyang. The closest big city to Xiaolangdi is Luoyang (about 45 km). This city has about1 million inhabitants and is well known also to foreigners for its famous historical past. It has been the capital of China through 10 dynasties in former times. Overview The Xiaolangdi Multipurpose Dam Project is located at the last gorge of the middle reach of the Yellow River. The main purposes of the project are: -flood control, - ice jam control, - sediment control, - irrigation, - water supply, - hydroelectric power generation. The project consists of many structures, these are 10 intake towers, 9 flood &sediment tunnels, 6 power tunnels, 1 underground powerhouse, and 1 zone dearth and rockfill dam with a sloping impervious core, 154m high, with a crest length of 1317m. The powerhouse mainly features 6 turbine and generator units of 300 MW, totalling installed capacity of 1800 MW and annual energy output of5.1 GWH. The total storage capacity of the reservoir is 12.65 billion m³ of which 5.1billion m³ is live storage. Of the Yellow River drainage basin, 694,000 km2 or 92,3percent is located upstream of Xiaolangdi Dam Site. Xiaolangdi is located in a key position for flood and sediment control of the Yellow River. Upon completion, Xiaolangdi Dam and Reservoir will effectively mitigate catastrophic floods, the control level will be increased from the present less than 100-year return period up to 10,000 years. Also, it will reduce severe flooding of the river bed of the lower

Jan 1, 1999

By Subhash Sethi

The WIPP (Waste Isolation Pilot Plant) Project near Carlsbad, New Mexico. is a research and development project sponsored by the U.S. Department of Energy, designed to demonstrate the safe disposal of radioactive waste. A mine (repository) is being developed 2150 feet below the surface in a thick salt bed, which will serve as the disposal medium. The underground ventilation system for the WIPP project was originally designed based on a fixed project scope. The design criteria and ventilation requirements were developed for the performance of various activities as then envisioned towards the achievement of this goal. However, in light of new information and actual site-specific experience at WIPP leading to a clearer definition of the scope-related programs and activities, it was realized that the existing ventilation system may need to be modified. A re-assessment of the ventilation requirements--based on the current status of the facility and a clearer definition of the scope of the experimental programs, waste storage methodology, mine developmental activities. and current equipment list--indicates a two- fold increase in underground airflows from 210,000 cubic feet per minute (cfm) to 425,000 cfm. Various options to provide the increased airflow to the underground facility were considered and analyzed. Based on the techno-economic analysis, safety and environ- mental considerations, and other conditions unique to a facility like WIPP, it was decided to construct a new shaft to serve as the primary fresh air intake, along with the installation of additional fans in parallel with the existing set up. Low cost and the ease with which the new design could be implemented and integrated into the existing ventilation system with minimum impact on current activities and projected schedules were the guiding factors in designing the shaft and related ventilation modifications.

Jan 1, 1987

By L. S. Fountain

A national survey, 1978-1980, found 180,973 waste impoundments used by industrial mining, municipal and other interests. Possibly 27,000 contain hazardous materials. The potential hazard of leaks polluting water supplies is a growing concern. An electrical technique was developed to efficiently and speedily detect and locate leaks in geomembrane-lined liquid impoundments without emptying the contents. A potential applied between the liquid and earth causes electric current to flow through leaks in the insulating geomembrane material to ground. The cur- rent density around the leak is used to detect and locate the leak. Field tests show single and multiple leaks 2.54 cm in diameter or less can be detected and located to within less than 30 cm.

Jan 1, 1986

By Liu Hongkang, M. J. Virnig, Yang Xianwan, Zhu Yun

A new technology for recovery of gold from loaded carbon developed by Kunming Institute of Technology is introduced. The principle, production practice and results are described.

Jan 1, 1993

By T. M. Biddle

If an accident occurs at a mine, the mining company, its parent and affiliates, and its supervisory employees may face substantial -- and sometimes unexpected -- liabilities and costs. This presentation surveys the likely sources for post-accident exposure, including wrongful death and personal injury claims, mine closure/operational disruptions, and government civil and criminal actions against the company and its employees.

Jan 1, 1986

By Julia Herhold

The demand for sustainable and profitable/efficient projects within the tunneling and other underground engineering sectors grows rapidly. Construction tasks play a key role within the project conduction, whether as primary (tunneling), secondary (e.g., mine securing) or tertiary processes (e.g., workshops). The construction tasks of primary processes create the main structures, such as tunnels, which resemble the main project goal. For the secondary and tertiary processes, the purpose of the task shifts. The main goal is to provide structures, such as the securing of the cavity and workshops, that enable the project and enhance the efficiency of the primary conduction underground. To plan and optimize the conduction of construction tasks underground, whether they are identified as primary, secondary or tertiary tasks, the work preparation can be used. This method, known from the above ground construction, can be adapted and used underground. The approach of a digital work preparation tool combines, connects and adapts the main tasks “choice of procedure,” “logistics” and “site planning.” In addition, the digital tool is connected with digital models (construction, site, surroundings). With the adaption and forward projection of the work preparation, underground constructions (e.g., tunneling) can provide a more sustainable and efficient outcome.

Jun 13, 2023

By John D. Smart, John W. Sager

The following paper is an evaluation of the instrumentation programs on recent Corps of Engineers tunneling projects. The authors have first-hand knowledge of the NORAD Cheyenne Mountain Complex (NCMC) Expansion Project. Information on the other projects comes from conversations with those directly involved in the instrumentation programs and from referenced reports. The specific objectives of this paper are: (1) to state the purposes of the instrumentation programs, (2) to discuss the benefits gained from the instrumentation, and (3) to present conclusions from this study that will provide guidance to those planning instrumentation on future projects. Presentation of detailed descriptions of the projects and instrumentation data is limited to that necessary to the accomplishment of the above objectives. NCMC EXPANSION PROJECT The NCMC is located at a depth of approximately 800 feet in Cheyenne Mountain near Colorado Springs, Colorado. For the current expansion project new chambers were mined to accommodate a new diesel power plant and associated cooling and air handling equipment. During 1971 some 55,000 yd3 of granite were mined through existing access tunnels for this expansion. A model of the new excavation is shown in Figure 1. The light shaded areas are new openings, and the dark areas are portions of the existing operating complex. The large chamber to the right is the power plant chamber and has a span of 67 ft, a height of 50 ft, and a length of 172 ft. The other large chamber on the lower level is the cooling tower chamber and has a span of 38 ft, a height of 45 ft and a length of 185 ft. The small chamber on the upper level has a span of 20 ft and is 27 ft high and 140 ft long. Other major excavations are the 18 ft diam air tunnel

Jan 1, 1997

By George E. Aikens

Prolonged subzero climatic conditions impose some unique engineering problems for the developer and operator of open-pit mines in the Far North. The remoteness of the job site and the extremely cold, long, dark winters severely tax both man and machine in the quest for the Arctic's rich mineral wealth. Undoubtedly the singular most troublesome problem for the engineer is Permafrost which underlies about 201o of the land area of the world and about 85% of the state of Alaska. Permafrost has its impact on building construction and mine excavation, while posing a more pervasive threat to the-delicate ecologic balance within the Arctic wilderness. Yet the difficulties associated with mining up North may not be as overwhelming as has been previously supposed. For example, the lowest temperature recorded at Point Barrow is -560F, whereas Montana has recorded -69.7° F.. There are no specially designed machines for mining and construction in the Arctic, and efficient equipment utilization is maintained through proper operation and servicing techniques. However, neither equipment or people can be assumed to function normally at -40°F. Special techniques in drilling, blasting, and ripping are being used to yield economically competitive ores. Overall, a fundamental understanding of the nature of Permafrost will allow the engineer to deal expeditiously with an Arctic mining venture and at the same time to deal fairly with Arctic environment.

Jan 1, 1972