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By Joseph P. Gildner, Michael S. Kucker, Robert A. Robinson

Considerable controversy seems to exist over the extent and nature of information that should be provided in design-build type contracts. Much of this controversy may relate to the types of owners, ranging from private industry to state and federal agencies that are implementing design-build. Philosophies for the development of geotechnical information ranges from no information to a thorough investigation approaching that needed for final design. Several recent projects, such as the Channel Tunnel in Europe, Whittier Tunnel in Alaska, Tren Urbano in Puerto Rico, and Sound Transit in Seattle have taken varying approaches to providing and interpreting geotechnical information for bidders. The pros and cons of these various methods are discussed and assessed.

Jan 1, 2001

By S. Rajan

Familiarity with NEMA standards and the influence of the power supply on the motor-load system permits the user to make the necessary decision as to whether a standard or special motor is needed for his particular application. This paper highlights the more important aspects of NEMA standards for ac induction motors from the application engineer's standpoint and the effect of the power supply on motor characteristics.

Jan 1, 1975

By Jacques L. Mauboussin

The EUROPEAN ORGANIZATION for NUCLEAR RESEARCH (CERN) has undertaken the construction of a LARGE ELECTRON POSITRON COLLIDER (LEP), near GENEVA (Switzerland). The facility includes the main 27 km long tunnelled ring, 18 shafts, 20 experimental caverns and many auxiliary galleries. Roughly 800 000 cu.m were excavated in the molasse at 50-140 m depths, using roadheaders for caverns and auxiliary tunnels and 3 WIRTH, 4.5 m diameter, fullface TBMs for the main circular tunnel. Each TBM performs 25-30 m/day. Provisory lining behind them uses either precast concrete elements or shotcrete. Works a e being carried out by a joint-venture of European contractors led by FOUGEROLLE (France).

Jan 1, 1987

By Thomas E. Krakowski

INTRODUCTION This paper presents a method of calculation of internal moments and thrusts in tunnel liners of any material. The method is intended for hand calculation, but as it is numerical in nature it can be programmed for use in computers. The information required for design or analysis is presumed active internal and external pressures, the effective moment of inertia and cross-sectional area of the tunnel liner, the liner's modulus of elasticity, and the coefficient of subgrade reaction of the material surrounding the tunnel. Starting with active external and internal pressures and following the procedure described herein using the structural properties of the liner and surrounding medium, external passive reactions and internal moments and thrusts are calculated. The method is intended for use by design engineers. GENERAL Experience has shown that flexible tunnel liners have less internal bending stresses than those calculated using classical structural theory applied to free-standing arches. In fact, liners which are very flexible in relation to the surrounding soil or rock have virtually no bending moments when compared to free-standing arches supporting equal active loads. In order for this phenomenon to occur, the original active pressure diagram must be "modified" by additional external reactions (passive pressures) from the surrounding material, so that the thrust line within the lining follows the centroid of the tunnel arch more closely than that of a similar free-standing arch. These passive pressures are reactions developed through outward deflection of the tunnel liner. Thus, the outward moving portions of a

Jan 1, 1979

By A. J. Hendron, L. L. Oriard

INTRODUCTION Controlled blasting is used at some time during most civil engineering projects where there is rock excavation. Controlled blasting is often necessary because the blasting must take place in the near proximity of adjacent structures. In other instances, the blasting is controlled because a smooth perimeter is desired to minimize rock support and overbreak. The construction of tunnels and shafts for subways, rock excavations for foundations and the excavation of road cuts for interstate highways, sometimes require blasting operations which must be conducted in an urban environment. Unfortunately, blasting operations produce unwanted sounds and vibration along with their beneficial effects. Thus, in the writing of specifications for blasting in an urban environment, potential damage to adjacent structures by ground vibrations must be considered, possible damage to windows from airblasts must be considered, potential damage from fly rock must be considered, and the discomfort to people from ground vibrations, airblast, and noise must be taken into account. The contractor or the owner's engineer is faced with determining the maximum weight of explosives which may be detonated without damage to structures on adjacent property. If the weight of explosive is overestimated, the resulting damage to adjacent structures may result in costly losses. But, if the engineer or contractor is too conservative, and the weight of explosive becomes too restrictive, progress of the project may be curtailed and the cost of excavation will increase accordingly. The potential for damaging adjacent property is becoming more important in construction operations today. In the past, the plaintiff had to prove negligence in some states in order

Jan 1, 1997

By C. J. Bise

Virtual reality (VR) is a concept in which the human experience of perceiving and interacting with a computer-modeled environment is achieved through the use of sensors and effectors. It is an advanced form of computer graphics. The images are generated based on where the user looks and how the user moves. As personal-computer-based (PC) instruction gains acceptance as an innovative approach to providing safety training, VR can provide a multisensory, rather than merely a multimedia, mode of presentation. New technology continues to be introduced into the mining industry to meet the productivity needs of coal and noncoal producers. There is also an increased need for more innovative training of mine workers. New technology and equipment designs often affect the basic causes of accidents. For example, the development of cabs and canopies for underground coal-mine equipment has reduced the number of accidents related to roof falls and rib rolls. However, safety-training specialists then had to focus on the machines themselves, because the modifications had the potential for causing "pinch-point" accidents. In fact, although the overall physical demands on mine workers have diminished, there has been an escalation in the concerns about trauma from repetitive physical activity. Thus, health-and-safety training specialists have shifted their atten¬tion to the recognition, evaluation and control of workplace hazards (Hancock and Hill, 1995). Recognizing that the spatial relationships of a workplace convey more information about hazards when experienced rather than described, trainers agree that simulation is the method of choice. Unfortunately, until recently, simulation systems were either simple software programs that did not come close to portraying the real experience or were complex hardware systems (such as flight simulators) that did, but at a cost of millions of dollars (Fritz, 1991). However, researchers and training specialists are excited about an emerging approach to work-force education based on virtual reality. VR is also described as cyberspace, immersive simulation, artificial reality, telepresence, virtual environment or virtual world (Meyer and Dunn-Roberts, 1992; Peterson, 1992). It represents a group of concurrent advances in computer and interface technologies. They enable an individual to interact in a multisensory way with a computer-generated environment. To achieve this, a typical VR system incorporates a computer that contains the necessary databases for producing realistic images and audio; a head-mounted display (HMD) or screen for viewing the images; and a three-dimensional controller, joystick or data glove for interacting with the computer-generated environment. If virtual reality is to become an effective tool for the safety training of mine workers, its attributes will have to be measured against other forms of delivery. Accordingly, Carr (1992) listed the following areas in which VR should be considered the method of choice: ? When training mistakes would be costly. ? When the necessary environment cannot be experienced in the real world. ? To build interfaces that are sensible and can be manipulated. ? To make training situations really "real." ?To make perceptible the imperceptible.

Jan 1, 1997

By J. Paraszczak

Underground metal mining involves many challenges. Economic slowdown, tough international competition and sometimes volatile metal prices put constant pressure on mine operators to increase productivity and to reduce production cost. At the same time, countries such as Canada, the United States and Australia are experiencing skilled labor shortages that might even stall development of certain mine projects. Furthermore, some stages of underground production take place in particularly hazardous environments where the safety and health of miners is at risk. Automation of some processes in underground mining is one of the promising avenues to alleviate some of these problems. Loading and haulage are among the most critical operations and areas where implementation of autonomous vehicles has been targeted. However, although health and safety issues are a primary driver to opt for automation, the latter should ensure an acceptable level of productivity and pro?tability. With this in mind, this article focuses on the factors affecting operational effectiveness of autonomous underground loading and haulage equipment and the means to maximize it.

By Simon J. McDonald

In late 2007 Neptune Minerals Plc. commissioned Genesis - a leading consultancy and engineering company affiliated to the Technip group - to undertake a Seafloor Mining Conceptual Study for mining of Seafloor Massive Sulphides (?SMS?) in Neptune?s New Zealand licenses. A key deliverable of the study was information to de-risk the perception of SMS mining for investors the minerals, and that deep-sea mining of SMS material is technically feasible, commercially viable and can safely be managed as a sustainable marine resource industry. The aim of the study, completed in April 2008, was to evaluate alternative existing marine technologies for seafloor mining, ore lifting, dewatering and surface offtake, considering the following parameters: ? Efficiency; ? Reliability; ? Safety; ? Environmental impact; and ? Cost

Jan 1, 2008

By W. P. Blacutt

A financial-economic model incorporating physical, market and policy variables has been developed for mining investment in Bolivia. Additional risk criteria emanating from political instability, new mining legislation, recent environmental regulations and a new minerals taxation system are accounted for and are integrated into the investment decision model. Results of the model indicate that geologic and market variables have the dominant effect on the investment-worth function. Among policy variables, exchange rate and taxation policies have the most significant influence. Depreciation allowance for infrastructure development has negligible weight in the investment-worth function. The business structure of the firm considering investing in the Bolivian Polymetallic Project, is found to be an instrumental factor in the investment-worth outcome.

Jan 1, 1995

By Dan Witkowsky

In an increasingly environmentally conscious world, mining's importance to society has often been misunderstood and even maligned by the public. Extreme and impractical ideas have often been presented to children because of the lack of accurate, timely resource materials available to educators. In the late 1960s. two mining engineers, S.P. "Pi" Warren and C.L. "Lindy" Barker, became aware of this situation. They proposed to develop a summer field course to provide a factual overview of the minerals industry for teachers. The pair believed that teachers could become better informed to educate students, and future generations, about mining. These two Colorado Mining Association (CMA) members felt that such a course could reduce much of the misunderstanding about this vital industry. This could be done by providing a balanced perspective of mining, not only for kindergarten-through-grade-12 teachers, but also for the students they would be teaching during their careers. Students who better understood the minerals industry could better formulate an unbiased view of it. The course would seek recognized authorities from industry, academia and government who would lecture in their respective fields of expertise. The course would provide a total concept of the coal, aggregate, metals and industrial minerals industries. It would include geology, geophysics, exploration, mining, processing, marketing, product applications, economic, mining history, careers, and environmental responsiblity. When possible, site visits would permit educators to view operations and to meet the men and women who are industry leaders. Teachers would pay a small tuition fee. The balance of the program expenses for each teacher would be paid through scholarships provided by industry and individuals. The "total concept" idea obtained the support of the minerals industry. The support of CMA's Education Committee and the Colorado School of Mines (CSM) was obtained in 1968. Colorado's Commission on Higher Education approved teacher recertification credits through CSM's Office of Special Progams and Continuing Education for those successfully completing the program. The first six-week series of classes presenting the total concept of the indus¬try was held at CSM in 1969. In 1977, the CMA Education Foundation Inc. (CMAEF) was established as a Colorado nonprofit corporation. The "Total Concept of the Mining Industry" (Total Concept) course was placed under its sponsorship. CMAEF is dedicated toward this continuing education program (Table 1). In 1994, the course was streamlined to four-weeks for six hours recertification credit.

Jan 1, 1997

By H. X. Li, A. Correa, M. M. Zhang, W. Xuan, M. Andrade

"With increasing demand for steel and depletion of high-grade iron ore deposits, more research efforts are being directed toward extending the life of existing ore reserves and developing technology to treat low-grade iron ore resources. Among all the reported technologies, biotechnologies in mineral processing – specifically bioleaching and microbially induced flotation – have emerged to be considered as low-cost, environmentally friendly potential alternatives to many of the current mineral processing techniques. This paper provides a comprehensive review of current research on the use of microorganisms for iron ore beneficiation and, further, discusses the applicability of bioleaching, bioflotation and bioflocculation for the beneficiation of low-grade iron ores.IntroductionIncreasing global demand for raw materials has led to diminishing resources of high-grade iron ore. As a result, the mining and utilization of low-grade hematite, limonite, specularite, siderite and goethite ores have attracted more and more attention. However, these types of iron ores are of complex paragenesis and fine disseminated grain size, and often contaminated by phosphorus in the form of solid solution. The distribution of phosphorus throughout the iron mineral crystals prevents the effective use of physical separation techniques, and these complex ores are at present largely untapped due to a lack of cost-effective and efficient processing methods. Chemical leaching and roasting-magnetic separation approaches have been mainly tested only on the laboratory scale and are all either cost prohibitive or ineffective when used on low-grade complex iron ores."

Jan 1, 2015

By S. A. G. Poppen, M. B. Mirza, A. I. Cooley

The U.S. Department of Energy (DOE) is responsible for siting and constructing a licensed geologic repository for commercially generated high-level nuclear waste. Within DOE, the Office of Civilian Radioactive Waste Management (OCRWM) Program has this responsibility. To accomplish this mission, the OCRWM Program is engaged in a multidisciplined effort to identify, qualify, and develop repository sites. The current strategy of the OCRWM Program is to identify candidate repository sites in basalt, tuff, and salt and to develop exploratory shafts at those sites. Within OCRWM, the Salt Repository Project Office (SRPO) identified the salt site for the development of exploratory shafts. The proposed Exploratory Shaft Facility (ESF) in salt will have several primary purposes. The shafts will provide access to the reference repository horizon to permit in situ testing of the salt horizons in order to satisfy the following data acquisition needs: • Verification of the salt repository design parameters and validation of performance assessment models • Demonstration of the constructibility • Capability to adequately seal penetrations into the salt An exploratory shaft is required by 10 CFR Part 60 for the conduct of in situ testing at depth prior to submittal of a license application for construction authorization of a repository. Therefore, construction of an ESF will also facilitate the licensing process.

Jan 1, 1987

By L. Thompsen

High-pressure grinding rolls (HPGR) offer capacity increases, savings in operating costs and metallurgical advantages. The first installation of the Polycom HPGR in a copper ore treatment plant occurred in July 1995 at Cyprus Sierrita’s mining complex near Green Valley, AZ (Fig. 1). Until that time, the benefits this technology offers for copper and gold ore were only demonstrated on testwork. In other industries, such as diamonds, HPGR have proven to be reliable in industrial-scale plants and have set a new standard for this kind of ore treatment plant. HPGR are also successfully used for the comminution of coal, blast furnace slag and in cement and pelletizing plants. The installation at the Cyprus Sierrita Mine should prove the economical benefits in commerical-scale copper mining, confirming the results of comprehensive testwork(Fig. 2).

Jan 1, 1996

By D. Symonds, A. J. Richins, M. G. Nelson

Mining activities at Kennecott and Park City are similar in that both districts began operation in the last half of the 18th century, and both operated on a large scale for many years. However, they are different for two important reasons. First, the mines in the Park City district were always underground. The city of Park City was above many of those mine workings. It remained in place after mining activity stopped, and as the town became an up-scale ski resort, property values increased and the tailings dumps became desirable building sites. In contrast, Kennecott eventually became an open pit mine, and the growing pit effectively consumed many of the small towns that had grown up around the underground workings. Even towns on the periphery of the open pit were razed to allow for the disposal of mine overburden. Second, almost all mining activity stopped in Park City in the early 1970s, just as the first rigorous environmental legislation in the United States was enacted. (The Ontario mine operated sporadically until 1982.) Many mine structures, waste dumps, tailings ponds and piles, and tunnels were simply abandoned as the mining companies ceased business or were bought out. Kennecott, on the other hand, has been in continuous operation for more than 120 years, so a closure plan hasn’t been finalized. Nonetheless, environmental and social problems have arisen, and the company has had to address them.

Mar 2, 2022

By William E. Mead

The process of selecting a building site for a major structure is a complex procedure involving the consideration of a multitude of factors. The approximate geographic location for a structure is usually fixed by its intended function, though often there may be several site alternatives. Socio-economic, logistic, marketing and political factors are the primary site determinants. Also critical in site planning, however, are the environmental factors, both natural and man-made. These factors will influence the precise siting location within the limits allowed by the primary determinants and will dictate some of the basic design criteria. This paper discusses environmental factors, principally those which are natural conditions, that must be analyzed for five different groups of structures. The importance of thorough site environmental analysis based upon the principles of applied earth science is described. Significant elements to be considered in an appraisal of the geology, hydrology, seismology and meteorology are outlined.

Jan 1, 1968

By James Watson Baxter

Fluxes are used to promote pyrometallurgical processes that rely on adhesion (soldering or brazing) or fusion (gas and arc welding) to join metallic surfaces. In the adhesive processes, the metal surfaces to be joined are not melted; the join is formed using a filler metal with lower melting point than the base metal. Fusion welding involves use of heat in excess of the melting point of the base metal. The fused joint may be achieved either by simply fusing together metal surfaces brought in contact with each other or by introducing additional molten metal of similar composition to form a fused joint. ADHESIVE PROCESSES--SOLDERING AND BRAZING In order for molten filler metal, solder or braze, to spread in a manner that creates a successful join; the work surfaces on the base metal must be thoroughly cleansed. Fluxes remove stubborn oxide films and other surface contaminants, promote wetting of the work surfaces, add fluidity to the solder or braze, and enhance workability and ease of spreading. Brazing processes involve higher temperatures than those reached in soldering. Brazing fluxes, which must remain active and effective at the higher temperatures, differ from those employed in soldering. Some common fluxes used in adhesive processes are rosin for soldering tin and electrical connections, hydrochloric acid for use in soldering galvanized iron and other zinc surfaces, and borax for brazing. Soldering and brazing are similar processes, the primary difference being the temperature at which the joining operation is carried out. Soldered joints, produced with low-melting-point fillers (solders) that melt and flow at temperature less that 450°C (Althouse et al., 1988) can sustain loads of 1 to 1.7 MPa for extended periods of time (Anon., 1966). Brazing involves the use of filler materials with melting points commonly above 500°C and generally provides stronger joints than those obtained with solder. Both processes require local application of heat to melt and spread the filler so that the molten filler can wet (adhere to) the base metals by alloying and diffusion. Soldering Soldering is a means of joining metals by adhesion using a metallic bonding alloy as the filler, commonly a mixture of lead and tin. However, the adhesion of solder depends more on its ability to be keyed into minute surface irregularities than on alloying. The most familiar application is to provide and secure electrical connections. Soft solders can range from 1 to 70% tin with the remainder mostly lead. However, for general-purpose, soft-solder work, the alloy is commonly 50% lead-50% tin. Higher lead contents provide a wider range in the melting temperature and, for this reason, a 60% lead-40% tin alloy, which yields a mushy mixture, is used for wiped joints in lead sheet and pipe work. Conversely, 40% lead-60% tin alloys are used in soldering tin and other low- melting-point materials for which a narrower range of melting temperature is required. There are numerous other solder compositions such as tin-silver, 95% tin-5% silver and antimony-tin, 95% tin and 5% antimony (Carlin, Jr., 1992). Heat needed to melt and spread the solders is commonly provided by electrically heated, copper-tipped soldering irons or by means of torches; the solder is applied by hand, usually face-fed by means of wire. For wiped joints in plumbing and lead-cable splicing, the solder is manipulated with cloth pads. The molten solder wets the joint surfaces and is drawn, by surface tension, into minute fissures and capillary openings. Other applications involve use of induction heaters and furnaces with pre-shaped solder appropriately placed prior to fluxing and heating. In some processes, the joints are immersed in molten solder. Constituents and Role of Soldering Fluxes: Soldering fluxes generally fall into one of three categories: highly corrosive fluxes, intermediate fluxes, and noncorrosive fluxes. These same categories are sometimes designated inorganic, organic and rosin-based respectively (Althouse et al., 1988). Common constituents of each group are discussed briefly below. Corrosive Fluxes (Inorganic). Work with aluminum, magnesium, stainless steel, high alloy steel, aluminum bronzes, and silicon bronzes is carried out at temperatures in the upper portion of the range for solder operations. Soldering these materials requires use of highly active, corrosive fluxes to remove and prevent the formation of the especially stubborn, hard, oxide films that form on these materials upon exposure to the atmosphere. The corrosive fluxes consist of inorganic acids and salts that are applied either as pastes or dry. They are active at elevated temperatures and, since they remain active after the soldering is completed, must be completely removed. The main constituent of most corrosive fluxes is zinc chloride with a melting temperature well above the solidus temperature of most commercial tin-lead solders. It is made by the action of hydrochloric acid on zinc. When zinc chloride is used alone, un- melted particles of this corrosive salt get caught up in the joint and weaken it. For this reason, other inorganic salts such as ammonium chloride (NH4Cl) or sodium chloride (NaCl) may be added to lower the melting temperature. A mixture of zinc chloride and ammonium chloride is very effective because the excellent oxide reducing properties of ammonium chloride and the protective action of the molten zinc chloride combine to produce a fluxing action superior to that achieved when either is used alone. In addition to zinc chloride, ammonium chloride, and sodium chloride; common con-

Jan 1, 1994

By D. Dimitriadis, T. Polglase, W. Phillips, R. Jenny, M. Botz

Cyanidation processes for the extraction of gold or silver frequently involve the processing of sulfur-containing solids which react with cyanide to form thiocyanate. The formation of thiocyanate is an undesired side-reaction, and in many cases thiocyanate formation results in a prohibitively high cyanide consumption. With the increasing number of gold and silver mining projects which involve the processing of sulfide ores or concentrates or which utilize a biological sulfur oxidation process, more attention has been focused on minimizing thiocyanate formation and in treating solutions to eliminate toxicity associated with thiocyanate. Though not yet commercially applied, there are several technologies available to recover cyanide from thiocyanate to both reduce tailings toxicity and allow the reuse of cyanide otherwise lost to thiocyanate formation. This paper presents an overview of technologies available for recovering cyanide from thiocyanate along with estimated operating costs for the technologies. Pilot testing data suggests that in some cases, cyanide can be recovered from thiocyanate for approximately the same cost as newly purchased cyanide.

Jan 1, 2000

By I. K. Kapageridis

Environmental management and planning requires the integration of large volumes of disparate information from many sources and the analysis of this information with efficient tools for assessment and evaluation. Effective methods of communication that allow interactive participation in the planning, assessment and decision-making processes are also very important. The VULCAN software package from Maptek (Pty) Ltd comprises a large number of 3D graphical tools within an interactive 3D interface called ENVISAGE. These tools are designed and developed to help engineers and scientists to identify and solve environmental problems. The combination of VULCAN 3D Software and the I-SiTE 3D Laser Imaging system leads to powerful solutions for environmental management. This paper presents the capabilities of this integrated system and its applications for environmental management.

Jan 1, 2002

By Victor F. Hollister

Skam deposits considered as porphyry copper deposits have been classified into three basic prospecting models: (I) the skam deposit associated with a mineralized intrusive (Pima-Mission), (2) the deposit associated with a barren igneous stock (Ertsberg), and (3) mineralized rock that seems to have no clear association with apluton (Phoenix). Pima-Mission, Christmas, and many other copper-bearing skarns developed in carbonate sequences near mineralized intrusives form an important part of the deposit. Historically, copper derived from the mineralized intrusion accounts for less than half of the metal produced by most porphyry mines, as most mineralization occurs in the intruded rocks. Skam mineralization is an important part of wall-rock metal deposition, because carbonate sequences are preferentially replaced by sulfide and skarn minerals. Exploration for skam mineralization is an important phase of porphyry copper exploration. Impure carbonate beds can become better host rocks for skam deposits than pure carbonates, and these in particular should be included in porphyry-exploration programs if the impure strata are cut by the stock. Skam deposits can also form near stocks that are barren of sulfide. In this model, the two best ore guides are strata favorable for mineralization (usually impure carbonate beds) and the intrusive contact. Faults can also act as important ore controls. Some skarn deposits form that have no clear genetic connection with a stock, although intrusive rocks are known in the district. In such cases, the best ore guides are strata and district-wide faulting. Dikes and sills are also common and mineralization can locally prefer their contacts even though the igneous rocks are barren. Skam minerals are influenced by the chemical composition of the carbonate. Forsterite, brucite, tremolite, and talc are common in skams developed in dolomitic beds. Skams derived from calcic beds often contain wollastonite, calcite, stilbite, or idocrase. Diopside, however, is a common accompaniment of copper sulfide in skam regardless of the original composition of the carbonates. Tremolite and possibly other amphiboles and chlorite can occur significantly in the zinc-lead portion of skams. Gamets occur in magnetite, copper, and zinc-lead zones of skams, but are not as diagnostic as diopside for the copper zone or tremolite for the zinc-lead zone. A general desciption of skam-deposit mineralogy can be used to construct prospecting models of porphyry copper skams. An abstract of such a description follows.

Jan 1, 1991

By K. T. Valsaraj, L. J. Thibodeaux

Solvent sublation, the separation process for the removal of two hydrophobic compounds (penta- and trichlorophenols) from the aqueous phase, is discussed, as is a steady-state mathematical model for fire process. Solvent Sublation "'as conducted in a continuous countercurrent mode. The underlying mechanisms, theory and experimental details on the effects of process variables on removal efficiency are reported.

Jan 1, 1994