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By A. Wright, R. L. Kastelic, W. C. Feyerabend

Gold Fields Mining Corp. is evaluating gold mineralization beneath thick, wet alluvium at the Chimney Creek project, Humboldt County, Nevada. Contamination of reverse-circulation samples has been visually apparent since drilling began in the area. Tests have shown that, while contamination can affect assays, reverse-circulation holes appear to define mineralized zones almost as well as diamond-drill holes. To improve reverse-circulation sample integrity, several techniques were tried (including a stiff-mud injection system) but with limited success. Diamond-core drilling continues to be used in conjunction with reverse-circulation drilling to further delineate the mineralization.

Jan 1, 1993

By Jerry W. Danni, John E. Hardaway

Corporations today must comply with an ever growing number of complex and increasingly stringent environmental laws and regulations. An environmental audit program is an effective means in which to uniformly and systematically assess compliance, and to assure management that environmental liabilities are being minimized. This paper describes the design and implementation of Homestake Mining Company's environmental audit program, which has as its primary focus the objective verification of compliance with external requirements and internal good management practices. Major elements of the audit program discussed in the paper include: pre-audit preparation; on-site audit activities; and the post-audit report.

Jan 1, 1992

By P. Lausch, R. A. Mercer, J. F. Archibald

An innovative, polyurethane-based, spray on rock-lining material, designated Mineguard™ by its developers, is being manufactured to provide rapidly deployable area support coverage for specific use in underground hardrock mines. This form of surface-coating agent is intended to replace both shotcrete and the screen component of bolt-and-screen support systems. Due to the rapid rate of application, ease of installation and ability to achieve a 90% cure within seconds of application, Mineguard™ has considerable potential for use in mining and excavation operations that require a rapid rate of advance and a high degree of automation.

Jan 1, 1996

By W. A. Rickelton, A. J. Robertson

The ability of triisobutylphosphine sulfides to selectively recover silver from acidic sulfate solutions containing zinc and copper is described. Selectivity is explained in terms of the concept of hard and son Lewis acids and bases. Silver is stripped from the solvent using a novel strip feed (thiosulfate salt), and the recovery of metallic silver from the strip liquor by electrolysis or cementation is suggested. The high selectivity of extraction for silver and the utility of the stripping reagent are demonstrated in continuous, countercurrent, mini-plant tests. Important reagent properties, such as hydrolytic stability and low aqueous solubility, are discussed.

Jan 1, 1988

By J. L. Ellenberger, P. W. Jeran

A deep longwall coal mine was instrumented with a three-dimensional microseismic system in order to help determine the exact strata mechanics associated with the rock failure, redistribution of stress and the associated gob formation from the longwall. Overall, 5,000 well calibrated seismic events were recorded during the mining of the panel. Analysis of these events showed a close correlation between the seismic activity and advance rate, and that the majority of the recorded seismic activity occurs in the immediate area of the advancing longwall face.

Jan 1, 2002

By Don L. Jensen

With the successful implementation of supervisory control on the Bagdad concentrator grinding circuits, steps have been taken to expand supervisory control to the flotation circuits. This paper discusses the design and installation of the slurry delivery systems, analyzing instruments, level control devices, reagent pumps and supervisory software. Emphasis is placed on the design and installation of a reliable slurry transport system to feed the Courier 30 online analyzing instruments. Total system availability has been measured at plus 95%. Phase 1 acceptance testing of the supervisory software indicates a notable increase in copper recovery with no significant change in final copper grade.

Jan 1, 1999

By J. S. Y. Wang, R. C. Trautz

To evaluate the potential for water seeping into an underground opening, a 9-m- (30-ft-) long drift was constructed in the unsaturated fractured tuff at Yucca Mountain. Forty seepage tests were performed by releasing finite volumes of water at a constant rate into short test intervals located in boreholes positioned above the drift. The seepage threshold flux, defined as the liquid-release flux at and below which water will not drip into the opening, was determined for 10 test intervals. The seepage data, observations and model results indicate that a seepage threshold exists because a capillary barrier diverts water around the opening.

Jan 1, 2002

By R. W. Smith, S. A. Davis, A. M. Raichur, M. Misra

The flocculation of coal is typically accomplished by the addition of commercially available polymeric flocculants. Recently it was shown that biopolymers derived from microorganisms can also be used. The biopolymers flocculate coal efficiently and make the coal more hydrophobic. This increase in hydrophobicity can be utilized to separate coal flocs and can be used for reducing the moisture content of the flocculated coal. In this regard, flocculation and settling tests using biopolymers and synthetic flocculants were performed on fine coal. The experimental results are discussed and a transport model is presented for the time-dependent settling of fine coal.

Jan 1, 1998

By Timothy J. Napier-Munn, David M. Weedon

A model of mineral liberation was developed using back calculation techniques to determine breakage/liberation parameters in a similar manner to the way breakage parameters are determined in the Population Balance Model (PBM). Comminution and liberation data was collected from grinding mills operating at Pasminco lead/zinc mine Broken Hill, and Mt. Isa Mines copper concentrator, Mt Isa, Australia. Laboratory scale single particle breakage tests on ore samples from these sites were undertaken using a twin pendulum breakage device. Break- age/liberation parameters were then determined for several mills using back calculation techniques. The liberation/breakage parameters were then used to simulate mill liberation performance under varying conditions.

Jan 1, 1996

By Norman F. Sweeney, H. John Hovland

Over one million yards of granite were excavated for the Helms Pumped Storage Project, including a large underground powerhouse complex. Site investigations and in situ stress measurements were essential elements of the project design and provided the necessary geologic parameters for executing a finite element study of the powerhouse. A construction monitoring program, of geologic mapping, field instrumentation, and rock mechanics testing was then designed and has been successfully implemented. This paper reports on the scope of this construction monitoring program and explicitly compares the measured deformations to those predicted. As a result of this recent field experience the assumptions used in the finite element program are reexamined.

Jan 1, 1981

By D. W. Fuerstenau, P. C. Kapur

A model equation is presented for breakage of single particles as a function of the impact energy. The model takes explicit cognizance of the distribution of feed particles in their resistance to breakage as well as of the weakening of particles under repeated impacts. With the proposed formulation, it is possible to simulate the size spectra of progeny particles, interrelate quantitatively the so-called ‘t’ family of curves, derive an energy-size reduction relationship, compute the primary, energy-free breakage distribution function, and predict the optimum level of impact energy for a given size reduction task. Published data on single-particle impact grinding are in agreement with the model.

Jan 1, 1995

By J. C. Cawley

Improvements in today's maintenance practices are mandatory as more complex and productive machines evolve in the mining industry. By keeping machine reliability high through improved maintenance procedures, overall mining costs can be reduced. The Bureau of Mines is investigating diagnostic maintenance systems for underground mining machinery. A hydraulic expert diagnostic system and an electric motor predictive diagnostic system have been designed and installed on a Joy 16CM continuous miner. An electrical diagnostic system has been designed and installed on a Joy 14CM continuous miner. Each system is functionally described and the relative merits of expert diagnostic systems versus algorithmic diagnostic systems are discussed.

Jan 1, 1992

By Emil O. Frind, David W. Blowes, K. Ulrich Mayer

The multicomponent reactive transport model MIN3P can be used to simulate the evolution of pore water, pore gas, and the mineralogical composition in mine waste environments. The model is formulated for variably-saturated conditions, considers transport of dissolved and gaseous species, and describes geochemical reactions based on a partial equilibrium formulation. Reaction processes included are complexation, oxidation-reduction, ion-exchange, mineral dissolution-precipitation and gas exsolution- dissolution reactions. An example application, describing the generation of acid mine drainage and subsequent reactive transport for a ID-vertical profile in a tailings impoundment near Elliot Lake, Ontario, is provided.

Jan 1, 2000

By Maxine Wiber, Ross D. Gallinger, Brain A. Lewis

Poirier was an underground copper and zinc mine located in Northern Quebec that operated between 1965 and 1975. There are 5 million tonnes of acid-generating tailings, which have contributed acidity and metals to the Kananewesig and Kistabiche Creeks. The final closure plan incorporates the placement of all reactive material into the tails basin, installation of a geomembrane liner over the tailings deposit and a one metre soil layer to protect the liner. The environmental effect of the residual seepage was assessed from an ecological risk perspective. The Reclamation Plan has been accepted, and work commenced in 1998 to restore the site.

Jan 1, 2000

By Por J. B. Evans

El mantener un beneficio óptimo sobre todo el conjunto de un emplazamiento minero necesita una constante puesta al día de las estrategias operativas. En esencia, cada estrategia es una combinación particular del gasto del capital previsto, el flujo de ingresos y el tiempo transcurrido. La selección de una estrategia basada en el beneficio potencial requiere que cada estrategia contemplada con un ordenador, un análisis tal puede ser engorroso. Este capítulo discute o desarrolla una técnica de "corte rápido" que asigna una relación de beneficio a las estrategias alternativas e identifica aquellos aspectos de una estrategia que producen mayor impacto sobre el beneficio. Esta técnica puede proporcionar valoraciones rápidas de suficiente precision para muchas de las decisiones de las estrategias operativas que se toman sobre la marcha en minas que se encuentran en explotación.

Jan 1, 1982

By Sangwhui Cho

In comminution processes including crushing, grinding and pulverizing, the efficiency of the comminution system is very low. Since the early 1980s, research has been conducted to increase the efficiency of pulverizing mills. Additionally, the application of microprocessors and Personal Computers to process control have come into general use. Given appropriate models of the process and control algorithms, these systems can economically control comminution processes. The ring-roller type mineral pulverizer is known as an energy saving mill. In this study, a control strategy to increase the efficiency of this type mill is explained.

Jan 1, 1992

By David Royston

Conventional straight-radial SAG mill pulp lifters suffer from incomplete discharge of the rock portion of the charge. The resulting backflow of undischarged rock limits pulp lifter performance and is the major source of wear in pulp lifters. Backflow is increased in pulp discharge cone systems where multiple channels converge towards the central diversion cone. This paper covers recent experience with pulp lifter and discharge cone design supported by a single particle motion model that illustrates the discharge and backflow characteristics of pulp lifters, including the impact of discharge cone configuration.

Jan 1, 2005

By D. R. Zhu, H. S. Chiang, Y. M. Jiang, S. S. Peng

Two types of underground tests on three types of shield supports, 2-leg, 4-leg, and chock shield, were con- ducted to measure the horizontal movement of the canopy against the immediate roof. In no friction tests, steel rollers were placed between roof and canopy top, while in friction tests normal direct contact was used. Results indicate that the canopy for 2-leg shields always moves forward during setting, whereas there was no forward movement for 4-leg or chock shields. Based on the test results, a model for active horizontal force was proposed.

Jan 1, 1990

By Geoff Beale

In terms of their hydrogeology, most open pit mines can be divided into three categories. There are mines that occur above the water table, mines that extend below the water table in high permeability rocks and mines that extend below the water table in low permeability, tight formations. Mines that occur above the water table do not experience major ground water seepage. It may some- times be necessary to construct in-pit trenches and sumps to remove water from precipitation. But dewatering or enhanced drainage measures are typically not required. Open pits that extend below the water table in high permeability rocks find it cost-effective to pump from dewatering wells. This is done to lower the water table below the working pit floors, creating dry or depressurized conditions in advance of mining. If the rocks in the mining area are homogenous, complete drainage of the entire mining area may be achievable by pumping from wells. In this case, it is not necessary to consider drain- age enhancement. However, there are many open pits and excava- [ ] tions that can lower the water table using conventional wells, but for which drainage enhancement is also an integral part of the dewatering system. The Sleeper Mine in Nevada is an example of this. Hydraulic layering at Sleeper has prevented downward drainage of water as the main water table is lowered. In addition, there are many mines that have areas of low permeability wall rocks that do not freely drain as the surrounding water table is lowered. Ground water seepage also creates difficulties in mines that occur below the water table but for which lowering of the water table using conventional wells is not feasible because of the overall low permeability of the rocks. The volumes of water involved may be small. However, it is necessary to deal with all of the water inside the pit as mining proceeds. It is not possible to dissipate pore pressures in the wall rocks in advance of excavation.

Jan 1, 1997

By R. A. Metz, James W. Clark, William C. Dixon, Kevin L. Wiley, Thomas R. Couzens

This paper is a description of certain geologic aspects of the Inspiration mining operation. It is not a geologic description of the Inspiration deposit nor an exposition of all the geologic work involved in the development and exploitation of the deposit. A few specific examples of the application of geology and geostatistics to the mining process are given to illustrate the progress that has been made in making the Inspiration Mine more efficient and cost effective, and a statement of the philosophy of geologic applications is offered.

Jan 1, 1992