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By C. G. Janes, N. Finkelstein, L. M. Jr. Johnson

In May, 1966, the General Services Administration (GSA) announced a program to encourage additional domestic production of copper in the interest of national security. Upon learning of the copper production expansion program, Duval Corporation entered into negotiations with GSA for development of the Sierrita copper-molybdenum property under the program. Agreements between the GSA and Duval Sierrita Corporation, a wholly owned subsidiary of Duval Corporation, were concluded in 1967, with the Sierrita Concentrator beginning operation in 1970 at a designed capacity of 72,000 STPD. Subsequent additions and modifications have expanded capacity to 90,000 STPD. This property, located approximately 20 miles south of Tucson, Arizona, represents an investment including working capital of about $200 million. These funds were provided from an $83 million loan from GSA, repayable in copper valued at 38 cents per pound, $48.75 million of bank loans subject to U. S. Government V- loan guarantees, and Company capital contributions. Current general operating statistics for the concentrator are listed below: Ore Grade 0.32% Cu., 0.030% Mo. Daily Tons Milled 90,000 STPD Annual Copper Production 94,600 Tons Annual Molybdenum Production 15,000,000 Lbs. Annual Silver Production 1,135,000 Ounces

Jan 1, 1976

By S. Henley

There is much in common between the requirements of open-pit mining and quarrying operations. Both involve the extraction of large volumes of material from surface excavations. The principal differences are of degree: open-pit mining of materials such as coal or gold generally involves the extraction of only small volumes of 'mineral' and large volumes of waste-they are operations with very high stripping ratios, and are made viable only because of the high unit value of the extracted mineral. In quarrying operations, the unit value of the mineral - sand, aggregate, limestone, or clay - is much lower, but stripping ration Are also lower. Thus the same techniques of geological modelling, reserve estimation, and pit planning are applicable, as is shown in two examples from the British quarrying industry. In each case, a primary requirement is the definition of production volume or tonnage. Sometimes, this need may be addressed simply by the use of a survey data processing package. However, in other cases, such as the two examples addressed in this paper, of sand and clay quarries, detailed assessment of the variation of mineral grades is a vital part of the exercise, and simple volumetric modelling cannot in itself be sufficient. In these cases, a block model approach using simple logical and numerical post-processing is also required to obtain required parameters for commercial classification of the products to be extracted. Pit designs themselves may be optimised by use of algorithms such as Lerchs-Grossmann, but the value of mineral produced can be dependent on factors other than its grade in any one part of a single pit, and the 'optimised' pit itself must be considered only a good sub-optimal. Given the right degree of healthy skepticism, and a software package with sufficient flexibility to be adapted readily to the rather different requirements of the quarrying industry, there is no reason why the quarrying industry should not benefit from the many years of investment in mining software technology.

Jan 1, 1989

By Biao Qiu

Longwall and/or room-and-pillar mining operations in multiple coal seams could not only induce subsurface and surface subsidence but also cause interactions between these mined coal seams. The interaction might destabilize mine structures and subsequently induce additional strata movements. Mechanical models to utilize the predicted subsurface deformations to assess the interactions and the consequences have been developed. The models are incorporated into a computer program, CISPM-MS, for predicting the final surface movements and deformations as well as the mining interactions associated with multi-seam coal mining operations. It predicts final surface movements and deformations caused by the individual mining operations and by the interactive effects. The program can also be used to assess mine structural stability in multi-seam mining operations. The paper presents the developed interaction models and their application in surface subsidence prediction caused by multi-seam mining operations. A case study involving mining in two coal seams, using longwall and room-and-pillar mining methods, respectively, will be used to validate the program.

Jan 1, 2013

Abraham E.M., 465 Adam K., 151, 203, 249 Agioutantis Z., 137, 389 Alley M.M., 301

Jan 1, 2007

By F. Woodcock, A. R. Laplante

A test to characterize the amount of gravity-recoverable gold (GRG) in an ore is described. Typical GRG results are given and possible uses are discussed. The overall database, which includes 68complete tests, is presented. The ore samples treated had an average GRG content of 63% of the total gold in the sample, with a standard deviation of 20% and a range of 3% to 97%. Both the F8(, of gold and the GRG content at a grind of 100% finer than 850 pm correlate well with the overall GRG content (at 80%finer than 75 pm). The primary use of the test is to determine whether gravity recovery should be used and how. Results can also be used to predict gravity recovery, as many of the ores tested are from plants employing gravity recovery. Gravity-circuit simulation can be used to refine recovery estimates or for optimization studies.

Jan 1, 2000

By B. Dabrowski, J. D. Miller, D. Halbe, J. Hupka

An air-sparged hydrocyclone (ASH) mobile system was evaluated for continuous stripping and recovery of cyanide (the AVR process) from process water at a gold plant site. The ASH unit performed exceptionally well as an absorber. HCN was removed from the gas phase in a single one second pass with an efficiency exceeding 99%. HCN concentration in the discharged gas phase was lower than 10 ppm, which provided for a safe working environment. The stripping efficiency, controlled by the Henry’s Law constant, exceeded 40% in one pass.

Jan 1, 2004

By Klaus Schönert, Martin Botsch

In common high intensity magnetic separators, the magnetic particles are deposited on ferromagnetic matrices, such as expanded metals, steel balls or grooved plates, inserted into a strong magnetic field. The nonmagnetic material is flushed through the matrix chamber. Discharging the magnetic particles is only possible if the magnetic field is reduced to zero (e.g. high gradient magnetic filtration for the purifying of kaolin) or the matrix chamber is moved out of the field by a rotor (e.g. the Jones Separator). Therefore, these separators perform only in a batch or semicontinuous mode. A real continuous operation requirs transport of the deposited magnetic material to an outlet where it can leave the separation chamber inside the field. One possibility for accomplishing such separation and transport is through the use of a rotating induction body with a certain shape, such as a spiral.

Jan 1, 1995

By Michael J. Mankosa

Increased emphasis has been placed on recycling consumer and industrial waste products. This trend has created a new industry that is focused on recovery/ separation of byproducts from waste material. As a result, interest has increased in the development of separation systems designed for the recycling industry. Much work has been done in this area. However, existing techniques developed for minerals beneficiation are often ignored. An example of is the foundry industry. There are currently more than 3,000 foundries in operation throughout the United States. Each consumes between 9 and 900 t/d (10 and 1,000 stpd) of sand for mold production. Either silica, chromite or zircon is, used in various combinations with chemical or clay binders. After casting, the sands are typically discarded into a landfill. This practice has become an environmental concern, especially the disposal of chromite and zircon. Silica sand is not environmentally sensitive. But it is used in greater abundance (6 to 7 Mt/a or 6.6 to 7.7 million stpy)and thus has prohibitive haulage and landfill costs. Current technology for sand reclamation involves thermal treatment to remove residual binders followed by dry mechanical attritioning (Leidel, 1993; Klein, 1994). This approach results in high losses due to fines generation and high costs associated with thermal treatment. As a result, this approach has shown only limited success. Stringent regulations are also affecting the disposal of secondary materials, such as plastics and metals. This is particularly true for the ferrous and nonferrous scrap metal industry. It plays a major role in industrial recycling of steel, aluminum and copper. Applications such as wire recycling present challenging problems since a hazardous byproduct (plastic insulation) is generated by the recycling.

Jan 1, 1997

By Raymond Sandiford, Kenneth Xu, Taehyun Moon

Tunnel approach structures situated in slow moving earth flows are subjected to significant earth pressures. The authors have developed a system, utilizing collapsible concrete columns, that limits such loading. The system uses an array of collapsible concrete columns in front of the structure to absorb downslope movement and limit-imposed loads. This concept has been modelled using 3D FEM analyses and a rudimental lab test. For implementation, the collapsible columns would be prefabricated in strengths to mimic the soil strength profile. This concept has merit, and analytical results demonstrate that collapsible columns are a viable means to limit loading.

Jun 23, 2024

By W. H. Andrews

DEFINITION OF BAUXITE The term "bauxite" (1) dates back to 1821, when it was assigned to a deposit of red earthy material outcropping near the village of Les Baux in Southern France. Chemical analysis indicated the presence of aluminium oxide, iron oxide and water. Deposits of bauxite are widespread throughout the world although the major developments occur within 30 degrees of the Equator. Essentially bauxite is the product of weathering and leaching of a variety of sediments or rocks, generally in a high-rainfall tropical or sub-tropical climate, resulting in the enrichment of the aluminium oxide content. It is characterised by the presence of one or more of the minerals, gibbsite, boehmite, and diaspore. The other constituents are usually clay, (typically kaolin), hematite and/or goethite (iron-oxides), anatase (titanium oxide), and possibly silica as quartz. A variety of minor elements may be present, such as calcium, magnesium, phosphorus, vanadium, gallium, manganese, and many others in very small quantities. Organic compounds are normally present from development in association with a soil horizon where vegetation may be encouraged by the high rainfall necessary for bauxitisition. The physical form depends upon the geological history of the deposit and correlation also exists with the mineralogy. Older deposits which have been subject to burial are invariably hard and compact with the alumina predominantly occurring as boehmite or diaspore, while the more recent, surface deposits are frequently less compacted and gibbsite is the dominant alumina mineral. In these later deposits, the physical form can vary from the fine red soil (terra rosa) of Jamaica to the Weipa pisolites to the cemented Arkansas type. The presence of concretionary structures is an important aid in identification in the field.

Jan 1, 1984

By Bruce K. Cantrell, Stephen W. Stein, Kenneth L. Williams, David Hassel, Harvey Patashnick

In June 1992, the Mine Safety and Health Administration (MSHA) published the 'Report of the Coal Mine Respirable Dust Task Group; Review of the Program to Control Respirable Coal Mine Dust in the United States." As one of its recommendations, the report called for the accelerated development of two mine dust monitors: (1) a fixed-site monitor capable of providing continuous information on dust levels to the miner, mine operator, and to MSHA, if necessary, and (2) a personal sampling device capable of providing both a short-term personal exposure measurement as well as a full-shift measurement. In response to this recommendation, the National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Research Center, initiated the development of a fixed-site machine-mounted continuous respirable dust monitor. The technology chosen for monitor development is the Rupprecht and Patashnick Co., Inc. tapered element oscillating microbalance. Laboratory and in- mine tests have indicated that, with modification, this sensor can meet the humidity and vibration requirements for underground coal mine use. NIOSH is continuing that effort by developing prototypes of a continuous dust monitor based on this technology. These prototypes are being evaluated in underground coal mines as they become available. This effort, conducted as a joint venture with MSHA, is nearing completion with every promise of success. The immediate benefit of this effort will be to researchers, regulatory personnel, and mine personnel, by permitting evaluation of specific mining practices to see which expose mine workers to excessive dust levels. Using this information, mine personnel can optimize mining procedures to reduce dust exposure. MSHA and the operators will also be able to use the dust concentration data to judge whether dust plan parameters are adequate to continuously maintaining environmental dust levels below the applicable standard. The second development recommended by the Dust Task Group was a person-wearable version of the continuous dust monitor. It will be a monitoring system designed to provide a measurement of worker exposure to respirable dust, both during and at the end of the shift.

Jan 1, 1997

By J. J. Moore

Combustion synthesis, or self-propagating high-temperature synthesis (SHS), reaction systems are discussed with respect to thermodynamics and kinetics. In particular, the effect of the process parameters, e.g. particle size, [All] ignition and combustion temperatures, on these self-sustaining reactions is discussed. Combustion theory is used to investigate the effect of the overall actuation energy of the SHS reaction on the combustion front propagation rate and in obtaining a clearer understanding of the transition from stable to unstable propagation. Finally, examples of the application of combustion synthesis to advanced materials processes are made, in particular the synthesis of Ni-Ti-X intermetallic shape memory alloys, TiC-AI2O3 and ZrB2-AI203 ceramic composite materials.

Jan 1, 1992

By E. Spyridonos

Sustainable development in the mineral industry requires a paradigm shift from purely economic to multi-objective decision-making, considering economic, social, environmental and governance criteria. The commonly accepted aim is responsible stewardship of non-renewable resources. State-of-the-art 3D geological and mine modeling software technology can contribute to meet this objective as reliable and accurate geological models form the basis for an optimum management. The benefits obtained by the application of computerized modeling are illustrated at hand of three studies. The examples cover global and local producers of industrial minerals in fully developed as well as development countries. They refer to different levels of planning, from initial resource assessment over long-term planning to the generation of rolling forecast for operative planning in a running mine.

Jan 1, 2003

By Morgan M. Sears

In recent years, one large mine collapse and numerous smaller bump events have resulted in a renewed interest in coal bump research. With numerical modeling, the Energy Release Rate (ERR) calculation quantifies the ?release? of the gravitational potential energy of the rock mass into the environment as mining progresses. This release of energy can occur passively in the form of heat and sound or dynamically in the form of pillar bumps or rock bursts. From the initial application of a calculated energy release rate in the deep hard-rock mines of South Africa, the ERR was found to have a significant correlation with the risk or potential of damaging coal bumps or rock bursts. In this research, an ERR calculation is incorporated into the modern LaModel program to facilitate the analysis for potential coal bumps. Initially the ERR calculations in LaModel are verified using a case study of cut sequences originally modeled using the MULSIM/NL program. Then, the ERR calculations are applied to a bump-prone mine in Southern Appalachia were a number of different pillar recovery cut sequences were used in order to minimize the risk of bumps.

Jan 1, 2009

By R. J. McGregor, Deepak Malhotra

Engineers frequently encounter situations where decisions that are counterintuitive to the logically trained engineering mind are made because of other influences, whether they be financial, social, cultural, or environmental. Such influences can overrule the "logical" decision-making process. The aim of this book is to explore some of the nontechnical issues, which most engineers don't learn about in school, that can have a major impact in the mining industry. This chapter gives a brief overview of this volume and introduces the topics that will be addressed.

Jan 1, 2001

By R. G. Reddy, A. E. Torma

Bio-treatment of uranium contaminated soils from Fernald using the bacterium Thiobacillus ferrooxidans was investigated. The experimental results showed that extraction of uranium upto 99 percent from soils were obtained with 10 percent pulp density suspension and with addition of iron (3000 mg/l) after bio-remediation time of seven days. Application of the results to industrial practices is discussed.

Jan 1, 1995

By Drew F. Holbrook

Most of the siliceous rocks of the Arkansas Novaculite are novaculite, but they also include some chert, siliceous shale and, rarely, sandstone. Novaculite is defined as a homogeneous mostly white or light-colored rock, translucent on thin edges, with a dull to waxy Juster, and comprised almost entirely of microcrystalline quartz. The most plausible theory of origin for novaculite is that primary silica from submarine volcanism was picked up by organisms and deposited as amorphous silica, which was subsequently converted to microcrystalline quartz (novaculite) through diagenesis. The Arkansas Novaculite crops out over an east-west distance of 200 miles in the Ouachita Mountains of Arkansas and Oklahoma. Three divisions of the formation have been defined: a Lower Division, almost entirely massive light-colored novaculite; a Middle Division of interbedded dark chert and shale; and an Upper Division of massive calcareous novaculite. The Lower Division and most of the Middle Division are Devonian in age, and the remainder of the Middle Division and all of the Upper Division are Mississippian. The massive novaculites of the Upper and Lower Division attain their maximum development along the southern and central outcrop belts of the formation in Arkansas, and it is these rocks that are the source of current silica production. The calcareous novaculite of the Upper Division weathers readily to a light-colored, porous, less brittle rock, and in places to tripoli deposits. Currently tripoli is mined from a single deposit near. Hot Springs, Arkansas, and the rock is processed for highly specialized filler and abrasive applications. In the vicinity of Hot Springs, Arkansas, certain novaculite layers from the Lower Division with unique textural characteristics are quarried and processed into whetstones. Several small quarries produce this rock for two local and one out-of-state whetstone-fabricating plants. Chemical analyses of composite samples of novaculite from both the Upper and Lower Divisions taken at widely separated localities average 99 percent SiOz indicating a substantial resource of high-silica rock.

Jan 1, 1978

By J. M. Keating, R. L. Wiegel

Those processing plants which depend on flotation for their mineral separations are always looking for reagents which are cheaper, more selective or in some other way may provide improved economic performance. This paper describes the rationale for and some results from applying a statistically based approach to reagent testing in those flotation plants which still rely on experienced operators for manual flotation control.

Jan 1, 1986

By A. T. Yu

Once exploration is complete, "winning" of the ore can be viewed as fundamentally a bulk handling proposition. Whether it is to strip, break, size, extract, load, haul, or even process, the success of each of these phases will depend upon how effectively one can utilize-the methods and tools that are available in bulk handling. Since as much as 30 to 60% of the total delivered price of raw materials can be attributed to handling and shipping (ref. 1), this expenditure may spell the success or failure of an entire mining venture. In fact, it has become increasingly evident that handling and shipping are so intimately associated with mining that only when they are duly considered throughout the mine-to -smelter master plan as an integral part of a total system can an optimum operation be expected and the most economical ton of ore obtained, this total systems approach should not only take in handling and haulage in and out of the mine, but also storage and transfer at the terminals (ref. 2,3,t), including ship and barge loading and unloading which are likewise a major consideration (ref. 5). Much has been developed during the past century in bulk handling, particularly in its expanding use in the mining industry. In view of the major role bulk handling has played and will continue to play in mining, in commemorating AIME's centennial, this paper will attempt to outline the state-of-the-art at this three-quarter point of the 20th century - one that is marked by its industrial revolution and rapidly accelerating technological advances. Bulk handling systems Although many developments in bulk handling are worth noting. The most significant during the past three-quarters of a century are: the total systems approach to solving problems, automation, the increase in speed and capacity.

Jan 1, 1971

By Gary Beerkirkcher

INTRODUCTION The mine hoisting equipment that is selected and installed at a mine is for the lifetime of the mine and, therefore, it is extremely important that a proper choice be made. Several types of mine hoist designs, including double drum hoists, single drum hoists, friction hoists, and various special designs of these, are available to¬day. Each has advantages and disadvantages and they should only be used in suitable applications. Drive systems for mine hoists must be evaluated together with the mechanical systems for each hoist application. It does not make sense to properly select the hoist mechanical system and then choose a drive system that turns out to be a bottleneck. MINE HOIST TYPES There are two basic types of mine hoists available in the world today: the drum hoist, on which the hoist rope is actually stored during the hoisting cycle, and the friction (Koepe) hoist, which merely passes the rope over the wheel during the hoisting process. Drum Hoists Single Drum Hoist: A single drum hoist (shown diagrammatically in Fig. 1) can be used as a service or production hoist with the cage or skip in balance with a counterweight (Figs. 2 and 3). It can efficiently service one or more levels, since the location of the counterweight at any time is not important. As a pro¬duction hoist with skips in balance, the single drum hoist is best used for single level hoisting. All rope adjustments for proper spotting must be done manually for the single drum hoist. This has to be done periodi¬cally to compensate for rope stretch. A variation of the single drum hoist is the divided drum hoist. If multilayer winding is necessary, the single drum hoist must have a divider to allow a sep¬arate compartment for each rope. If a counterweight is used with a divided drum application, the counter¬ weight rope can be wound on a smaller diameter (Fig. 4). Consequently, it moves a lesser distance than the main conveyance and rope adjustment problems are re¬duced. Double Drum Hoist: A double drum hoist in oper¬ation is shown in Fig. 5. Double Drum Hoist With One Drum Clutched: As a service hoist with cage and counterweight, a double drum hoist with one drum clutched (Fig. 6) can serve several levels efficiently. The advantage of having the clutched drum is that it allows rapid adjustment of ropes due to initial stretch. Some users may prefer the single drum hoist with manual rope adjustment, while others consider the added expense of the second drum and clutch is justified to make rope adjustments quickly. The value of this feature for a particular application should be discussed with the hoist manufacturer. As a production hoist with skips in balance for a multi¬level operation, the clutch can be adjusted for efficient hoisting from any level. Double Drum Hoists with Both Drums Clutched: There are also double drum hoists that have both drums clutched (Fig. 7). The main advantage claimed for this type of hoist is that if something happens in one of the two compartments, the hoist can operate in the other compartment to raise and lower men and sup¬plies. This feature is particularly favorable if there is only one shaft entrance to the mine. Multiple Drum Hoist: The multiple drum hoist, a South African innovation, is a type of drum hoist about which everyone should be aware. Basically, it uses two hoist ropes per conveyance which at great depths per¬mits use of smaller ropes and smaller drums. There are none in use in the United States today. However, they should be considered in very deep mines. Friction (Koepe) Hoists This hoist (Fig. 8) was introduced to the mining world by Frederick Koepe in 1877. The basic prin¬ciple of the friction hoist is that the hoist rope passing

Jan 1, 1982