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By Yannis Faitakis, Brenda M. Wright, Gail Powley, Mark Hamblin, Randy B. Paine

A major problem in the ore extraction process is the high degree of variation in the mix of materials that make up the mined ore. The mix of materials makes it extremely difficult to characterize and predict the behavior of the ore when it is processed. The Quality Production Database (QPD) tool was successfully used in order to predict and transfer information regarding the quality characteristics of the ore being delivered to the extraction and hydrotransport unit operators. This paper describes the use of QPD in the prediction of various ore characteristics at the Syncrude Canada Ltd. processing facility.

Jan 1, 2000

By Houston Kempton, David Atkins

Mining in semi-arid climates can produce environmental impacts that will not begin for hundreds of years, but once started, may continue for thousands of years. Pit lakes may eventually exceed toxicity thresholds as metals are evaporatively concentrated, and slow unsaturated flow through acid-generating waste can eventually load several kg-SO4/m2-yr to underlying water tables. U.S. regulations are poorly equipped to respond to delayed and long-term environmental impacts, delaying permits as operators and regulators grapple with uncertainty. Improved uncertainty analysis, additional long-term mitigation options, and explicit regulatory guidance offer solutions to this dilemma.

Jan 1, 2000

By John A. Herbst, K. Rajamani

Process improvement is probably the most widespread objective of mineral process plant operators in the late 1980's. An important part of such improvements is dynamic optimization which involves reacting to inevitable plant disturbances in such a way that productivity is maximized at every instant of time. This paper describes the way in which mathematical models can be and have been used in dynamic optimization. Both off-line and on-line model applications are described.

Jan 1, 1989

By Richard M. Bennett

Twelve linear test foundations were constructed over an advancing longwall panel in southern Illinois, six were located along the centerline, and six in the maximum tension zone. One footing in each set was a control foundation constructed according to conventional practice. It suffered severe damage. Footings with reinforcing bare and post-tensioning had much smaller elongations, with the post-tensioning preventing cracking of the footing. Footing-soil interface treatments of plastic-on-sand and plastic-on-soil served to reduce damage. The addition of steel fibers to the footing had about the same effect as an interface treatment. Sill plate construction (butt-jointed versus lap-jointed) appeared to significantly affect the behavior.

Jan 1, 1986

By David Rolley

The extended weakness of dollar-denominated commodity prices during the past four years has often been attributed to, among other factors, the strong rise in the value of the dollar, and many U. S. producers have hoped for a recovery in metals and minerals prices once the dollar weakened in foreign exchange markets. The recent turnaround in dollar strength may put this view to the test quite soon. Hence a review of the role of exchange rate changes in the determination of the prices of world-traded metals and minerals may be timely. This paper has three parts. Part I reviews the recent summary record of price movements in commodity and foreign exchange markets. Part 11 reviews the distinct ways in which exchange rate changes influence the supply and demand sides of a representative commodity market. Part III then more closely examines copper and aluminum prices to highlight the potential differences in the effects of exchange rate changes for commodities whose production is dominated by geology and commodities which are processing-dominated. The paper also contemplates the likely implications of these differences for commodity prices in the case of a decline in the trade-weighted dollar. The evidence suggests that the degree of recovery for dollar- measured commodity prices may be very different for differing goods. And it may be the case that some commodities whose prices appear to have been most affected by exchange rate influences may show the least recovery in response to a fall in the trade- weighted dollar.

Jan 1, 1986

By Joseph A. Dos Santos

The Expanded Conveyor Technology, a rationalization of the conventional conveyor technology, allows us to apply the theory and principles beyond the current (perceived) limits. This was first prompted by the writer's advancements in Sandwich Belt High Angle Conveyors. The introduction defines the Expanded Conveyor Technology and outlines the range of applicability for the wide variations in conventional and non-conventional conveyors. The writing deals with the theory and design of sandwich-belt, high-angle conveyors in the context of the Expanded Conveyor Technology, including the equations of friction, hugging pressure and the continuity of hugging principle; curvature constraints and criteria for tension, curvature, trough, and belt construction; and drive and tension analysis, load sharing and traction, including "derived load equivalents."

Jan 1, 2000

By D. T. Kinard, A. A. Schweizer

An operational 9 meter (30-foot) high gold heap leach pile was investigated by excavating test pits up to 6 meters (20 feet) deep, obtaining bulk and relatively undisturbed thin wall drive samples, and observing the ore distribution patterns exposed in the test pit walls. The clayey ore is crushed, agglomerated with lime and cement, and deposited on the leach pads using a radial stacker. Laboratory tests performed included moisture-density, gradation, compaction, Atterberg limits, permeability (constant and falling head), and triaxial strength tests. Discussion is presented on the effects of agglomeration on the permeability and strength characteristics of the in-place ore. Also discussed is the effect of deposition of the ore using the radial stacker.

Jan 1, 1987

The purpose of this paper is to describe two systems designed to provide estimations in stratigraphic orebodies for the purposes of detailed mine planning. The first is a completely geostatistical approach and the second is a combined geostatistical/deterministic approach. The essential features of both systems are the estimation of stratigraphic ore boundaries and the subsequent use of those boundaries to provide stratigraphic (or zonal) control for block and point grade estimation (kriging). Both systems are illustrated by application to a section of, the Hilton orebodies, Queensland, Australia.

Jan 1, 1989

By C. Waddell

PDMI mines five different grades of ore. Shovel operators were experiencing problems differentiating one material type from another. In 1997 PDMI decided to try GPS ore control to aid operators in identifying material boundaries. Computer generated ore control maps and GPS data defining the shovels' position is fed to a computer on board the shovel. A monitor, located near the shovel operator, displays material types, their boundaries, and the shovels' position and movement in relation to the mining face. This information has reduced errors in material identification by 50%.

Jan 1, 1998

By Todd L. Hollingsworth, Jeremy K. Hobbs

In 2001, the Radomiro Tomic Mine located near Calamq Chile, added a tertiary crushing facility. An 84" wide mobile tripper is used to fill their tertiary crushing storage facility. This paper is a we study to demonstrate the drive and control systems in use on the tripper. Of special note is the design concept used to allow the system to operate multiple motors in both demand and regenerative modes through a single VFD. Also noted is the use of touch screen local controls, handheld radio controls, starting/stopping/ braking philosophies, safety device interfaces, and the local to remote control interface.

Jan 1, 2004

By Anthony Harding, Rodolfo D. Aradas, Juan M. Fernandez, Darío Tsingas

"The adoption of tunneled combined sewerage interceptors and outfalls leads to design linings which are often subject to internal pressures that are larger than the external pressures, resulting in significant tension loads. The need to meet stringent durability conditions for the normal design life of 100 years often drives client specifications to require a double pass solution with a cast in situ secondary concrete lining. However, improvements in concrete technology and the need to seek efficiency in terms of time and costs, have driven designers to consider single pass segmental linings. The Riachuelo Sanitation project in Buenos Aires is subject to these constraints both upstream and downstream of a sewage treatment plant. This paper describes how the challenges of up to 2 bar pressure differential have been addressed by careful analysis of soil structure interaction to ensure that the full benefit of external ground pressure is realized, resulting in a more optimal design for the constructor both in terms of cost and time. INTRODUCTION The construction of long sewerage interceptors and outfalls is becoming an increasingly common piece of infrastructure for modern urban cities facing a large water front and estuarine conditions, which are under a significant environmental burden imposed by decades of sustained growth. Such works intercept most of the distributed sewage discharges to then divert them to a central treatment point from which it will be finally diffused via an outfall into a water body capable to accept these discharges under acceptable environmental conditions. Depending on the magnitude of the sewage load to be handled, the configuration of the urban environment and the conditions of the receiving water body, both in terms of oceanography forces and seabed conditions, these schemes will vary in length, conveyance capacity and design and construction requirements. When conditions permit, the current trend is the execution of long outfalls using flexible solutions (such as the use of HDPE pipes) which usually require some form of concrete ballasted weights to resist off shore dynamic forces when directly laid over the sea bed. However, this concept faces limitations when the conveyance requirements indicate the need for large diameters (typically above 3000 m) and also when the outfall needs to avoid deep features off shore such as navigation channels. When this occurs, tunneling, particularly segmentally lined tunnel constructed by TBM emerges as the most feasible approach for large diameter, long deep outfalls. The operating conditions often result in internal pressures that are larger than the external pressures, resulting in significant tension loads in the lining. The need to meet stringent durability conditions for the normal design life of 100 years often drives client specifications to require a double pass solution with a cast in situ secondary concrete lining."

Jan 1, 2016

By D. M. Smith, M. J. Meulendyke, P. J. Moroz

An extensive program of marked ball wear testing (MBWT), laboratory corrosion studies, and worn ball surface analyses has been used to gain insight about the role of corrosion in the overall wear process. In some environments, localized corrosion is observed; the actual wear mechanisms in such cases are pitting/spalling and abrasion. Factors affecting the occurrence of pitting include the abrasiveness of the ore, corrosivity of the slurry, corrosion resistance of the media, and galvanic coupling effects. Elimination of pitting substantially improves overall wear resistance. When pitting is not observed, the contributions of general corrosion are significantly less.

Jan 1, 1988

By Fernando de Oliveira Durão

A complete computer package for the steady-state simulation, either in analysis or in design mode, of mineral processing flowsheets is described. The main features of the simulation package are: modular architecture, flexible structure and sequential solution strategy. Different detail levels of mathematical models of several mineral processing unit operations have been developed and implemented as unit modules (FORTRAN routines). Unit operations currently modelled are: coarse/fine crushing, grinding, screening, hydrocyclone classification, gravity separation, heavy media separation, froth flotation, high gradient magnetic separation and solid-liquid separation. In design mode, a simulation study is stated as a general non linear optimization problem. The objective function is a weighted sum of square deviations between the design specification set points and the calculated values, subject to non linear equality and inequality constraints. The optimization problem solution is obtained solving successive Quadratic Programming subproblems followed by inexact line search of an exact penalty function (Powell algorithm). One non trivial example is discussed, illustrating the design capabilities of the simulation package.

Jan 1, 1992

By D. Piper, J. Noble, M. Richardson, J. Wojcik, L. W. Cope

L. Cope Welcome. I am pleased to see so many people interested enough to stay until this last session of the last afternoon of the convention. Of the people on the panel here, everyone has done everything in placer mining, but we have tried to sectionalize it with each one of us taking a particular portion. Any one of us could probably answer any question. I am very pleased to see some well experienced people in the audience. To start the discussion, Joe, can you give us a brief comparison of pit and drill sampling? J. Wojcik They both have their place. If you expect your deposit is something that is going to have widespread fairly uniform grades, then the pits may be the way to go. If you are going to have something you have to trace for several miles down the river valley, you can't do it with pits and do a proper sampling job. C. McLain Joe, the end result of all of this is to go ahead and mine it if it is a deposit. Do you try to relate your drilling results to something in mining itself against the recovery, because the drilling in different types of ground will give you different kinds of recoveries, and mining in the end is what you are going to do? Do you try to relate this to your mining method?

Jan 1, 1992

By Vicki Seppala

Phelps Dodge Mining Company operates some of the world’s largest open pit mines. Safely mining in these deep pits requires the commitment to a proactive integrated slope management process. The slope management process also includes the continued look for improved slope design, construction, and maintenance of slope faces. This paper discusses integration of such technology as electronic programmable detonators, 3D imaging using ground-based LiDAR scans, and reflectorless slope monitoring systems in a slope management program.

Jan 1, 2005

By D. A. Day, H. L. Marsh, P. J. Stephens, C. A. Wiggins

Lightweight cellular grout backfill behind pipe-in-tunnel has been gaining increased acceptance in the tunneling industry and has proved to be both practical and economical. Two successfully constructed projects, the Upper Scioto West Interceptor Sewer (USWIS), in Columbus, Ohio and the Benbrook Pipeline Tunnel Project in Fort Worth, Texas will be discussed. The projects represent two different but successful applications of lightweight cellular grout backfill. The USWIS placed the grout behind precast reinforced concrete pipe, in water bearing limestone, and in close proximity to residential water wells. The Benbrook Project placed grout behind 6,096 meters (20,000 feet) of steel pipe from just two locations, eliminating major surface disruption typically associated with the placement of pumped concrete.

Jan 1, 1999

By Ray E. Harris

All of the major raw materials (silica, soda ash, limestone, and feldspar) needed to manufacture most grades of glass are found in Wyoming. Additional advantages for the manufacture of glass include the state's geographic location, a well-developed transportation network, a favorable tax structure (no corporate or personal-income tax), and low energy costs. Inadequate local markets and prohibitive transportation costs to other markets have been the major obstacles to developing a glass industry in Wyoming, the least- populated state in the nation. The Rocky Mountain region only recently became a major market for glass, especially for the Colorado Front Range and Utah's Wasatch Front. Currently, changing costs of the production of glass, an increased market for con- tainer glass in the Colorado Front Range, and innovative production and transportation ideas (e.g., production of selected types of glass and bulk shipments of specification-glass pellets) favor developing a glass plant in Wyoming. Thus, the Wyoming State Geological Survey (WSGS) and other state agencies have been conducting studies and contacting investors in an effort to attract a glass-manufacturing plant to the state. Between 1987 and 1993, three locations of silica-sand and -rock deposits were studied in Wyoming (Cassa, Plumbago Creek, and John Blue). Funding was provided by the WSGS operating budget and local and state Department of Commerce economic- development grants. The reports on these areas were released between 1988 and 1993. In 1988-89, a California-based company conducted additional drilling and feasibility studies and prepared to construct a glass plant in Cheyenne, using the Cassa silica source. However, due to losses incurred by some of their other investments, the company did not proceed. In 1997, the Wyoming Science, Technology, and Energy Administration (STEA) contracted a market study for glass manufactured in Wyoming, using information provided by the WSGS. The STEA contacted several major glass producers, and a major glass-producing company began feasibility studies in January 1998, for the construction of a glass plant. In June 1998, bids to supply brown beer bottles to the Budweiser brewery northeast of Fort Collins, Colorado, were submitted by at least two companies that were considering glass-plant sites in Wyoming.

Jan 1, 1999

By Kenny Lo

"SummaryFor more than a century, ground freezing has been a construction technique used in stabilization of ground by means of lowering the temperature of surrounding soil strata. This technique is used in circumstances where conventional grouting method is unable to achieve the degree of consolidation required to prevent settlement and water ingress during the execution of underground excavation. Whilst ground freezing is effective in imparting self-supporting characteristics to the excavation profile, it poses significant challenges when it comes to the New Austrian Tunneling Method (NATM) where sprayed concrete is used to support the freshly excavated ground. Sprayed concrete, if used in an appropriate manner, provides a fast, efficient and structurally-reliable means of supporting the structure, especially in underground construction. The evolvement in sprayed concrete technology is attributed to the development of concrete know-how, improvement of spraying technique with the use of automation spraying equipment, more in-depth understanding of sprayed concrete behavior and enhancement of materials used in production of high quality sprayed concrete Not only has this markedly escalated the prominence of sprayed concrete on wider perspective,. the positive development has also pushed sprayed concrete beyond its boundaries, enabling it to be embarked on area of application not considered possible decades ago. Nevertheless, sprayed concrete, for all its placement versatility, still depends largely on the technicality provision very similar to concrete to achieve the required quality. Parameters such as raw material grading composition, curing temperature and cement quality are some of the factors that can easily sway the quality of concrete from one extreme to another. Conducive ambient temperature is critical in ensuring optimum hydration of concrete. This is more important in sprayed concrete where temperature plays a pivotal role in influencing the early strength and long term strength development. The low temperature imposed by ground freezing is everything but ideal for competent hydration to take place. This paper outlines how the innovative use of sprayed concrete helps to overcome the adverse ambient temperature in the construction of a 110m underground pedestrian walkway utilizing ground freezing technique in Hong Kong."

Jan 1, 2016

By Changwoo Lee, Jan M. Mutmansky

Introduction Recognition of Coal Workers' Pneumoconiosis (CWP) as a major occupational disease has affected various aspects of the coal mining industry in the United States as well as in almost all major coal producing countries. Regulations related to the control of coal mine dust forced mine operators to modify their mining and ventilation practices. As the coal production record of the last 15 years shows, this had both direct and indirect impacts on the productivity and production costs. To identify the causes of CWP, many research efforts have been made through- out the world. Most of these studies were epidemiological in nature, attempting to pinpoint exposure and seam variables that affected the incidence of the disease. Other studies have been oriented toward the elemental and mineralogical composition of the coal dust in the mine atmosphere and in the miners' lungs. These studies indicate that there may exist some relationships between the characteristics of the coal mine dust and the prevalence of the disease. Some of the variables that are thought to affect the occurrence of CWP are the mass of the dust in the working place, the rank of the coal, the existence of certain trace elements, the free silica content of the coal, and the existence of other minerals in the respirable dust. A more complete description of these previous re- search studies has appeared elsewhere (Mutmansky and Lee, 1984). The behavior of particles in the human lung is known to be governed by their aerodynamic diameter, which is defined as the diameter of a hypothetical spherical particle with unit density that exhibits the same settling velocity as the given particle. Because of this fact, the aerodynamic size distribution of coal mine dust is one of the parameters to be determined along with the other physical, elemental, and mineralogical characteristics. The objective of this paper is to establish a strategy for providing coal mine respirable dust samples for characterization purposes using instruments that classify according to the aerodynamic diameter. In addition, several findings concerning characterization methods will be presented. Choice of Samplers Most of the gravimetric dust collection devices that can be utilized in a mine environment can be

Jan 1, 1986

By Richard L. Coleman

El trabajo de ensayo metalúrgico para desarrollar un flujograma es el que ahora describimos, comenzando con una información experimentada requerida en todo momento hasta llegar a un esquema final de flujo de un proceso. Tanto las pruebas de laboratorio como de planta piloto son revisadas adecuadamente sobre las experiencias anteriores.

Jan 1, 1982