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By Edgar O. McAlister

Associated with cordilleran intrusives of intemediate to acidic composition, gold/silver ores are generally found in the intruded host rocks which are adjacent to these intrusives. Generally precious metal deposits lie further from the intrusives than allied base metal deposits. For vented intrusives, the associated volcanics may constitute the intruded rock and form the host for precious metal accumulation. Potential field methods, particularly magnetics, can help to define unseen boundaries of intrusive systems and thus can point to generalized prospecting targets. Other clues arise from the intrusive system type, its emplacement fracturing, the host rock type and local magnetic changes caused by mineralization processes.

Jan 1, 1984

By John W. Reddy

The C&NW Ore Dock at Escanaba, Michigan, is a major terminal on Lake Michigan for iron ore pellets arriving from the Marquette Iron Range located 112 km (70 miles) to the north. In an average year, the terminal handles in excess of 8 000 000 Mg (LT) of iron ore pellets consigned to a number of major steel companies. It is important to the steel companies for both cost control and operating efficiency that each cargo be sampled as accurately as possible in order to determine the physical and chemical properties of the pellets. This paper describes the equipment and operating procedures of the sampling facility and Presents some sampling data.

Jan 1, 1985

By R. J. Caine

Like most major firms engaged in project management, Dravo Corporation faces a constant challenge to keep its management systems in tune with the ever-increasing demands imposed by larger and more complex projects. This paper suggests that one of the key elements in meeting this challenge is more effective organization of project data. It reveals some of the details of a program at Dravo's Minerals 6 Metals Division which seeks, through better organization of project data, to improve Dravo's capabilities in estimating, cost control, scheduling, performance reporting and material control. In particular, this paper discusses ideas Dravo is developing for improved job numbering, codes of accounts, requisition and purchase order numbering, inventory cataloging, and employee/badge numbering.

Jan 1, 1980

By K. Dagdelen

The definition and shortcomings of traditional cutoff grades are discussed. The concept of optimum cutoff grade policy which maximizes the Net Present Value (NPV) of annual cash flows coming from a mining project is introduced within the basic framework outlined by K. F. Lane. Several examples are used to demonstrate the shortfalls of cutoff grade policies obtained by various heuristic optimization techniques. An algorithm to obtain an optimum cutoff grade policy which maximizes the NPV of a project is given and described in detail.

Jan 1, 1993

By Walter Meintrup

On Nov. 4, 1981 the newly installed 1000tph wet-process iron-ore ball mill of A/S Sydvaranger completed its first four months of uninterrupted, successful full-load operation in Kirkenes/Norway. This 6.5m diameter mill is driven by a gearless ring or wrap-around motor of 8100kW at 13.1RPM - a first of a kind in this segment of industry. (Fig. 1) This paper analyses the reasons that have led to the selection of this type of drive over more conventional schemes, lists specific advantages of such large mills, and describes in some detail the installation in Norway. General aspects of possible design variations, and application information for designers and users of such mills conclude the presentation.

Jan 1, 1982

By Robert A. Bauer

Two basic types of subsidence occur in Illinois: pit and sag / trough. Pits develop over mines less than 165 feet deep and where relatively incompetent strata are found over the mines. Sag subsidence is found over mines as shallow as 75 feet and more generally over mines of greater depths. The percentage of subsidence and angles of draw associated with sag subsidence appear to be controlled by the rock properties at each specific site. The percentage of subsidence and angles of draw are smaller where the sites are not affected by geologic structures. An investigation to determine if a time factor based on the time interval from the date of mining to the subsidence events has shown that simple correlations with time, percent extraction, average pillar stresses, and pillar dimensions is not evident in Illinois.

Jan 1, 1982

"Foreword by Emily SarverAssistant professor, Mining and Minerals Engineering, Virginia Tech, Blacksburg, VAThe Mineral Processing Division hosted its fifth Student Poster Contest during the 2014 SME Annual Meeting and Exhibit in Salt Lake City, UT – and, by all accounts, it was a huge success! This year, the contest more than doubled in numbers of individual entries and schools represented. A total of 30 students participated, including 23 graduates and 7 undergraduates, representing 13 US and international institutions: Colorado School of Mines, Michigan Tech, Missouri University of Science and Technology, Montana Tech, New Mexico Tech, South Dakota School of Mines, University of Kentucky, University of Utah, Virginia Tech, West Virginia University, Autonomous University of Chihuahua (Mexico), UNAL Medellin (Colombia), University of British Columbia (Canada). In addition to constructing their posters, students submitted abstracts and gave short oral presentations highlighting their research. Based on tallied scores from all three components of the contest, the judging panel selected 1st, 2nd and 3rd place winners at the undergraduate and graduate levels, which were announced during the MPD Luncheon on February 26.In the undergraduate division, University of Utah’s Lucas Pich was awarded the 1st place prize for his poster “Solid-liquid mixing studies in lab-scale flotation tank using electrical resistance tomography.” His extended abstract is included in this issue of Minerals & Metallurgical Processing. Joshua Chidester, also of Utah, won 2nd place for his poster presenting “Evaluation of detectors for radiotracer RTD measurement by MCNP.” And Lucas Rojas-Mendoza, of UNAL Medellin, took 3rd place for his poster on “Preg-robbing in Colombian gold ores.”In the graduate division, 1st place went to Caelen Anderson, of the Colorado School of Mines, who also placed in this contest in 2012 and 2013! The 2nd and 3rd place prizes were awarded to Jacob McDonald and Joseph Halt, respectively, both of Michigan Tech. Extended abstracts describing the work of these up-and-coming researchers are also included in this issue.The 2014 Contest was chaired by Emily Sarver (Virginia Tech) and Lisa Schlink (Freeport-McMoran Copper and Gold, Inc.). Aaron Noble (West Virginia University), David Perkins (Derrick Corporation) and Derek Novotny (Eriez) graciously served on the judging panel this year.Special thanks are extended to all sponsors of the 2014 MPD Student Poster Contest, and to all student participants. Please watch for upcoming details on the 2015 Contest. We look forward to seeing you in Denver!"

Jan 1, 2015

By Warren C. Gerler

An overland belt conveyor system is installed for only one reason to save money. It must pay its way on a ton-mile basis over a stated period of time, and do so in competition with other forms of transportation. Such a system with its economies has recently been installed at Simco-Peabody's mine near Coshocton, Ohio by Link-Belt Company. Three miles in length, this system carries coal from open pit and underground mining facilities to the Conesville Power Plant of Columbus & Southern Ohio Electric Company. The coal was formerly trucked from the mine direct to the power plant; but over the years the mining operations have moved progressively farther and farther from the plant, making the over-the-road hauling distance correspondingly greater. Simco-Peabody has mining operations over a considerable area just east of the Conesville Station. The majority of the coal is recovered by conventional strip mining. Some underground mining` is performed by the high wall method.

Jan 1, 1963

By Robert W. Holliday

Natural resources are the reservoir from which society draws its material sustenance. Although there is a growing awareness of the need for aesthetic resources such as space for recreation and natural beauty, the basic resources are soil, air, water, and minerals including fuel. Minera's and all sources of energy gain in relative importance with advancing technology and expanding industrilization. In the highly industrialized economy of the United States, almost every aspect of man's life is touched in some way by a product of, the mineral; industries. Agriculture owes much of its productivity to mineral-based fertilizers, insecticides, and mechanical equipment. Modern construction, manufacturing, communications, and transportation are all dependent on nonmetallic minerals, metals, and fuels. Throughout history, those nations with access to minerals, and the technology for using them, have gained ascendency. Before World War II the leading powers also were, leading coal producers. In order of declining rank the five leading' coal producers were the United States, the United Kingdom, Germany, the USSR, and Japan. That the military victory went to the side with the greater' capacity to convert iron and coal into tools of industry, and weapons, is' more than coincidence. It is a fundamental' fact of existence. It is axiomatic that the United States must have a continually increasing supply of minerals if we are to meet the needs of our burgeoning population for a comfortable standard of living and for national security.

Jan 1, 1968

By J. H. Mackey

"Where can I obtain a reclamation bond today?" "Who is writing your bonds?" These questions are common and heard frequently. The fact that the Society of Mining Engineers has determined that two of the five environmental topics reviewed at the 1989 Annual Meeting relate to reclamation bonding indicates to me that those who are involved in the coal industry, no matter what capacity, remain very cognizant of the reclamation bonding dilemma.

Jan 1, 1989

By M. Kane, O&apos

BHP Iron Ore initiated research programs in January of 1995 to develop long term plans for decommissioning of the waste rock material at their Mt. Whaleback operation. More than 2 billion tonnes of waste rock were deposited during the past 30 years. Ultimately, the operators will deposit a total of approximately 5 billion tonnes in waste rock dumps constructed near the open pit. The Mt. Whaleback operation is located in a semi-arid climate adjacent to Newman, Western Australia, approximately 1200km north-northeast of Perth, Western Australia. The primary research program includes the development of technology for the long term performance of the waste rock dumps with respect to vegetation, slope stability, surface runoff, erosion, and water infiltration. This paper focuses on the design and implementation of a cover system to prevent water infiltration to the underlying waste rock. A laboratory program and the soil-atmosphere modelling completed to design the horizontal field test plots are described. The construction of the horizontal surface field test plots are discussed together with the field instruments installed to monitor performance. The key components of the instrumentation program are the design and installation of large scale field lysimeters to measure the unsaturated flow of moisture into the waste rock from the base of the cover layer. The cover system is designed to maximize infiltration during wet periods for subsequent evapo-transpiration while minimizing surface runoff. The result is a near zero net infiltration to the underlying waste material. A key feature of the design is the use of pit run waste material as the cover material. Monitoring is in progress and will continue for at least two annual wet/dry cycles. The optimum cover system should minimize the net infiltration of water to the underlying waste rock while maintaining physical and ecological integrity for long term performance.

Jan 1, 1998

By J. L. Vanderbeek

Investigations have been conducted at Chino Mines Company into the effect that SAG mill recycle material (critical size) exerts on SAG mill throughput and specific energy requirements. Tests were conducted on the laboratory, pilot, and plant scales, to evaluate the merits of alternative treatment options. Removing critical size material from the SAG mill circuit has been shown to improve new feed rates by 34% with a reduction in specific energy (kWh/ton) of 33%. Test results obtained to date are presented.

Jan 1, 1985

By J. F. Cornelsen

Wheel loaders are currently being used in many mining applications for a variety of reasons. While they sometimes provide the lowest loading cost, a primary advantage of the wheel loader versus other loading systems is the increased versatility and mobility inherent in a wheeled vehicle. The advent of large wheel loaders with much greater digging capability enhanced wheel loader usage in severe loading applications. To match these severe conditions, machines offered today were designed to work in these rocky conditions. Soon after the introduction of large wheel loaders into rocky conditions, however, it became apparent to many users that tire costs could at times account for up to 50% of total hourly operating costs on large wheel loaders. In some applications, tire costs alone pushed wheel loader economics beyond the economic feasibility for these jobs, prohibiting their use. In an effort to combat high tire costs, several attempts have been made to put fast moving steel around the tires to provide a strong interface between vehicle and ground. Some earlier attempts involved wrapping tracks around tires. Mechanical difficulties with these systems limited their customer acceptance. Subsequently, the development of protective tire chains came into favor. While tire chains offered added protection to the tires, the cost and maintenance of the chains remains a problem in 1972, the Dystred arrangement was announced for usage on a 6 cu yd wheel loader from Caterpillar Tractor Co. (See Figure 1). The Dystred offered the advantages of greatly increased tread life over conventional tires, as well as resistance to tread puncture in most situations. The arrangement basically employed a track system similar to that used on track type loaders. Pin and bushing wear often caused high hourly operating costs and excessive machine downtime. In addition, the connection of shoes through the use of links, pins, and bushings forced a limitation on too speed of the vehicle.

Jan 1, 1976

By Reese E. Mallette

This paper makes five major points which may be contributions to the art of limestone sinkhole engineering. First, solution cavity development in limestones is dependent in great measure on pyrite contained within the limestone. Second, rock failure is rarely involved in sinkhole problems, while soil failures are almost always the mode of occurrence. Third, draw down, depression of the water table, is a primary causative factor in sinkhole development. Fourth, lateral movement of vadose water along the soil-rock interface, sub-soil erosion, is the mechanism by which soil is stoped, raveled, piped, or removed from the soil cavern. Fifth, the ultimate or triggering factor in localizing a sinkhole collapse is any superposed mechanism which disrupts the continuity of an impermeable clay soil overburden. The above theses are presented as extensions of our observation and of published literature, with the suggestion that additional study of these mechanisms is warranted.

Jan 1, 1975

By W. V. Bluck

Higher coal quality is being recognized in potentially lowering the cost of power as measured at the bus bar. Assessment of potential coal supplies for most any given power plant is now going beyond buying at the lowest delivered fuel cost and is now taking into consideration other factors such as handling, storage, pulverization cost, boiler fouling, post combustion cleanup, and waste disposal costs. New measurements of quality are being considered now by those producing and those consuming the fuel by assessing numerous variables in the total fuel cycle to achieve the lowest possible power costs.

Jan 1, 1983

By D. A. Bird

Water chemistry data were used to identify the sources of ground-water and surface-water inflow to the IOZ block cave mine. Water samples were collected to obtain vertical and lateral hydrochemical profiles within different levels of the underground workings. Water chemistry data were evaluated in conjunction with geologic and structural information to define controls on locations of ground-water inflows, and to select targets for drilling and interception of water. Drilling has intercepted water-producing zones that were previously unidentified through mapping and drilling. The program has resulted in a reduction in water inflows to the block cave area.

Jan 1, 1998

By Laurence B. James

The California Department of Water Resources is concerned with the development, distribution, and protection of the State's water resources. Geologic activities of the Department relate to planning, construction, and operation of water projects, supervision of the safety of over 900 dams under state jurisdiction, and investigation and control of ground water supply. The Department is engineering oriented, and the role of the geologist is to assist with the solution of engineering problems. Some of these problems require the integration of many talents, including not only those of geologists and engineers, but also those of economists, lawyers, seismologists, chemists, geophysicists, and hydrologists, Frequently, a task force of several disciplines will attack a problem as a team.

Jan 1, 1965

By Paul Piercy

Bougainville Copper Limited operates a porphyry copper mine in Papua New Guinea. The waste dumps will contain 400 to 500 million tomes of rock at the end of nine life. The paper describes investigations carried out over a period of en years and highlights the problems associated with waste lump leaching in a tropical and seismic active region. Aspects discussed include mineralogy, chemical reaction, leaching rates, microbiological activity, dump stability, dump structures, effects of tropical conditions, seismic activity and topography.

Jan 1, 1981

By B. M. Eiter

The impact of fatigue is seen not only in its effect on the job performance of haul truck operators but also on the health of the operator and the productivity at the mine site. Its impact can even extend outside of the mine site to the health and well-being of the surrounding community (Fourie et al., 2010). In this paper, a case study of a small, surface mining organization is presented. The goal is to highlight the fatigue risk management system implemented at the studied mine site. Mine safety personnel who were interviewed discuss the changes made to the infrastructure of the mine, to administrative areas such as the number of shifts and the use of vacation time, as well as the implementation of new technology into haulage vehicles. This paper reviews how these changes are supported in the research literature.

By W. D. Elston, A. E. McLaughlin, G. B. Hampton, W. L. Barham, J. F. Murphy, W. H. Cundiff, J. W. Mulloy, R. G. Breuer, J. W. Shaffer

Introduction Alumina (aluminum oxide) is the material from which all the world's aluminum is produced. In the Western World, all the alumina is made from bauxite by the Bayer process. In the nearly 150 years since aluminum was first isolated by Oersted, the metal has grown from a laboratory curiosity to a position of major importance in the world's commerce. In terms of annual production rates aluminum is first among nonferrous metals. Oersted's discovery-reduction of aluminum chloride with potas¬sium amalgam-was improved on by Ste. Claire Deville, whose so¬dium amalgam reduction of aluminum chloride led to the commercial production of aluminum in France in 1855. Ste. Claire Deville's method prevailed until 1886 when Charles Martin Hall and Paul T. Heroult each invented a process for the production of aluminum by the electrolysis of alumina dissolved in molten cryolite. The inven¬tion by Karl Josef Bayer in 1888 of an economical process for making very pure aluminum oxide (alumina) from bauxite established the necessary link between known ores and the Hall-Heroult reduction process. Bayer's work completed the scientific base-the ore bauxite refined to alumina by the Bayer process (U.S. Patent No. 515,895), the alumina reduced to aluminum in the Hall-Heroult cell (U.S. Patent No. 400,766--upon which today's aluminum industry is founded. Small-scale production of aluminum in the U.S. began in 1888 utilizing the Hall cell. By 1903, bauxite properties and a Bayer process refining step had been incorporated into the production activities. On this base the aluminum industry in the U.S. has grown at an annual compounded rate of 15%. Since 1946 the annual growth rate has been 10%.1 The rapid growth of the industry is the result of many factors among which are the existence of widespread bauxite ore deposits; a sound and economic production technology; and the properties of the metal-lightness, strength, ductility, good electrical and heat con¬ductivity, and pleasing appearance, which lead to ever greater de¬mands for aluminum in an industrializing society. At the inception of the industry, the only market that could be found for aluminum was in the production of cooking utensils. How¬ ever, the rapidly accelerating industrial and technological development of the Western World soon created new needs for aluminum, and today aluminum is marketed in a broad range of industrial, commer¬cial, and consumer applications. The principal uses for aluminum are:' building and construction, 22%; transportation, 18%; electrical, 13%; packaging, 11%; consumer durables, 10%; machinery and equipment, 7%; other, 19%. The 1974 production of primary alumi¬num in the world was 14.5 million short tons, which at an approximate ingot price of 40¢ per lb puts a value of $11.6 billion on the industry product prior to fabrication. While aluminum is widely distributed in the earth's crust and is a major constituent of many rocks and soils, to date no method of extraction of aluminum from such nonbauxite material has been brought to commercial practice in the Western World. In the USSR alumina is produced by the complex processing of nepheline syenite, but elsewhere all commercial production of alumina is from bauxite. A brief discussion of recent developments and other processes for alumina is included in the subsection "Other Processes for Alumina," page 19-15. In early 1973, a major U.S. aluminum producer announced the successful development of processes for the production of aluminum from aluminum chloride. This achievement promises to exert a major influence on the future of the aluminum industry. In the initial com¬mercial application of this new technology, Bayer alumina will be chlorinated, and the aluminum chloride then reduced by electrolysis. Important claims for the new processes are lower energy requirements (one-third less than obtainable in Hall cells) and reduced labor costs. Capital costs are said to be no greater than for conventional plants. While the announced intention is to produce the aluminum chlo¬ride from Bayer process alumina, the new chloride reduction process will eliminate the other raw materials, carbon and fluorides, required by the conventional Hall cells. The electrodes in the chloride cell will not be consumed on the reduction process and the electrolyte will have, as the name indicates, a chloride rather than a fluoride base. 2. Bauxite Definition and Origin. Bauxite is a naturally occurring raw material composed principally of a mixture of one or more of the hy¬drated aluminum oxide minerals gibbsite (Al2O2 3H2O), boehmite (Al2O3 H2O), and diaspore (Al2O, - H2O), and impurities of silica, iron oxide, titania, and other various elements in trace amounts. It is an end or near-end product of chemical weathering. Depending on the amount of iron impurities, the color of bauxite varies from dark red and brown to pink to white. Some bauxite is finely divided, free digging earthy material, while other forms are dense and rocky, requiring explosives in mining. Many gradational forms exist. It is one of the most variable of mineral raw materials in chemical composition and physical appearance. It is generally believed that bauxite deposits resulted from intense chemical weathering of aluminum-bearing rocks or formations under tropical or subtropical conditions with alternating wet and dry sea¬sons. Topographic conditions were favorable for drainage and the in-situ accumulation of aluminum, iron, and titanium oxides. There was low to moderate topographic relief with a minimum of erosion during long quiet periods in earth history.2 The occurrence of bauxite is widespread and it has been found on all continents except Antarctica. Production was reported from 27 countries in 1974, at which time total world production was over 79 million metric tons. Of this production 76% was from seven coun¬tries-Australia, Jamaica, Surinam, Guinea, USSR, Guyana, and Greece-which ranked in that order of production. In Table 1 are shown typical compositions of bauxite from some

Jan 1, 1985