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By James P. Rider, Charles D. Taylor, Edward D. Thimons

Research was conducted to investigate how ventilation of a mining face is affected when scrubber flow is greater or less than intake flow. Tests were conducted in a full-scale surface test gallery built to simulate a mining entry with a continuous mining ma- chine at the face. Methane gas was released at constant flow at the mining face. Gas measurements taken at six locations near the face were used to evaluate how well the face was being ventilated. Increasing scrubber flow resulted in lower methane levels even when scrubber flow was much greater than intake flow.

Jan 1, 1997

By J. C. May, G. M. Elliott, J. J. Brady

Increased clearance was required in two railroad tunnels that were built about the time of the Civil War. Clearance infringements, whether they be excavation tights or caused by ice accumulation, reduce tunnel serviceability. Achieving increased clearance often means disturbing the ground and old ground support structures. Access and transportation needs dictate how and when the work can be carried out, and strongly influence the design approach and the methods used by the contractor to execute the work. This paper explores the pertinent considerations of the owner, the designer, the field inspection team, and the contractor in bringing this project to a successful conclusion.

Jan 1, 1997

By M. J. Klishis

This paper presents the findings of a study on roof bolter's hazard exposure. A "microanalysis" of accident data was combined with ergonomic observations of roof bolter operators to categorize bolting-related injuries, and, from this, a checklist was constructed. Bolting-related problems were identified as situations that could expose bolter operators to hazards. Approaches to avoid these situations were applied at six mining operations to evaluate specific problems in root bolting operations. The research emphasized the importance of analyzing worker behaviors in the context of mining situations and equipment-design problems that lead to human-error accidents.

Jan 1, 1996

By Regina N. Tempel, Timothy E. Eastep, R. Craig Ford, Bryce R. Roming, Geoff Clothier, Maggy F. Lengke

The Climax Mine, near Leadville, Colorado treats acid drainage in a lime neutralization chemical treatment system. Chemical treatment has been successful in reducing the concentration of metals to below surface water discharge effluent limits, but lime usage has not been optimized. A geochemical modeling approach has been developed to increase the efficiency of lime neutralization. The modeling approach incorporates two steps: (1) calibration, and (2) calculation of amount of lime needed to increase pH and remove metals. Results of our work quantify the lime treatment process and improve our ability to predict overall water quality.

Jan 1, 2000

By R. Sawyer, M. Sadler, M. Holdworth

Greens Creek is a high grade Ag/Au/Pb/Zn deposit located in southeast Alaska. Maximizing the Net Smelter Return revenue from the fine grained mineralization is a dynamic process given changes in metal prices, smelting terms, ore grades and flotation characteristics. This paper discusses the evolving concentrate production strategy, and how it is affected by such factors as ore and concentrate specifications and by market conditions. Also described is the development of an on-line computer program that provides the mill operators with real time NSR data and a means for optimizing Net Smelter Return.

Jan 1, 2002

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 Regina N. Tempel, Laurie S. Balistrieri, Lisa L. Stillings, Maggy F. Lengke

The Dexter pit lake, within the Tuscarora volcanic field in Elko County, Nevada, formed after closure of the Dexter mine. Mineralogy at the Dexter mine is related to widespread feldspar, silica, and chlorite alteration. Major mineralogy includes quartz, alkali feldspar, albite, phlogopite-biotite, hornblende, iron-titanium oxide, chlorite, kaolinite, smectite, illite, and sericite, with lesser amounts of calcite, zircon, apatite, and rutile. Trace element geochemistry is characterized by high levels of As, Ba. Cr, Cu, V, Zn, B, Zr, Li, and U. Detailed mineralogy and geochemistry are required for geochemical models to accurately predict trace element concentrations in pit lake waters.

Jan 1, 2000

By Glenn Mallory, Margarete Kalin, Ben Romanin

A waste management area of a copper zinc mine which is expected to be generating acid exceeding 1000 years is used as a research facility to develop a passive treatment approach to decommissioning the site. One of the processes proposed to be implemented in a lake with a one million cubic metre volume is biological polishing. To determine the expected performance of the process, model is constructed from experimental data collected in the lake. The model results and the field data represent a weak fit, but the discrepancies are useful indicators of key factors affecting the process, such as iron cycling.

Jan 1, 1995

By Olice C. Carter, B. J. Scheiner

The Bureau of Mines investigated the removal of two toxic/heavy metals (cadmium (Cd) and lead (Pb)) from brass foundry wastewater. Polymers, copolymers, guars, and gums were used in conjunction with calcium hydroxide (Ca(OH)2) and magnesium oxide (MgO) to remove the metals from solution. Several polymers were successful in removing Cd and Pb from the wastewater. The concentrations of Cd and Pb were lowered from 19 to 0.01 ppm and from 20 to less than 0.01 ppm, respectively. The methods investigated could easily be adapted to many existing wastewater treatment facilities and/or be used independently.

Jan 1, 1991

By L. W. Ashton

Geochemical exploration guidelines were developed from a study of 460 rock chip samples collected at nine disseminated gold deposits in Nevada. Obtaining high grade Au samples is difficult because gold content is extremely variable, even over 8 m (25 ft) distances. For reconnaissance sampling, pathfinder elements are reliable indicators with threshold values of 100 ppm As, 1 ppm Hg, and 50 ppm Sb. Arsenic is the most reliable of the three elements, being significantly enriched in all deposits. If the pathfinder threshold levels are reached with low Au content, more samples should be collected. Successful disseminated gold exploration requires large numbers of samples.

Jan 1, 1990

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 A. G. Wylie

The dimensions and shape both airborne and bulk amphibole-asbestos fibers are different from those of both airborne and bulk of cleavage fragments of the amphiboles. These differences are related to the mineralogical properties unique to the habit of asbestos, including the fibrillar structure, small fibril widths and distinctive crystal-lographic faces of fibrils. Criteria for distinguishing amphi-bole cleavage fragments from amphibole-asbestos include mineralogical properties observable in bulk samples and the dimensions of particles collected on air filters. It would be it very helpful to the mining and mineral industry lf these properties were recognized in the regulation of asbestos.

Jan 1, 1987

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 Husheng Li, Zhongli Wu

This paper discusses the fundamental strategies adopted in the simulation package FIRES developed for ventilation simulation under mine fires. These fundamental strategies include (1) fire characteristic curves specifying the development of a mine fire with time, (2) simulation of fume spread in a ventilation system, (3) determination of the aerodynamic effects of mine fires on flows; and (4) dynamic simulation of flow state under mine fires. The major functions of the simulation package are also addressed. The package has been used to simulate an experiment of mine fire. A comparison is made between the simulation results and the measured data.

Jan 1, 1993

By Heinz Hoberg, Fred Ulrich Schneider, Rudolf Diegel

The risk of contamination of dumped tailings and ground water by coal flotation reagents has been investigated by using the 14C-radiotracer method for adsorption and desorption measurements. The results indicate, that a high amount of the reagent components adsorbed on the tailings if there was no coal in the pulp. In coal flotation however a competitive adsorption behaviour could be observed, with the effect that only a low quantity of reagents adsorbed on the tailings. Mobilization tests showed, that only small quantities of reagents could be desorbed by rinsing water. Therefore the contamination of ground water should be low.

Jan 1, 1995

By Carl P. Maronde, William P. Barnett, Patricia A. Rawls

The commercial deployment of advanced fine-coal cleaning technologies depends on cost-effective approaches for efficient separation and ancillary operations in handling, dewatering, drying, and transporting coal fines. As a result of two solicitations under the High-Efficiency Preparation component of the Department of Energy Coal Preparation Program, several projects were initiated for testing and evaluation of emerging technologies and equipment that address operational difficulties associated with coal fines. This paper will update the status of those projects and discuss how the technologies they represent can ameliorate some problems associated with coal fines in today's preparation plants.

Jan 1, 1995

By Vanessa M. Torres

Diagnostic leaching tests provide a good indication of gold deportation in its various occurrence phases. With the results of these tests, possible flowsheets for difficult ore treatment can be established for further evaluation and plant operation can be optimized. The use of this technique can be extended, including heap leach evaluation and complex copper-gold ores. The results on the use of diagnostic leaching tests in gold ores from Companhia Vale do Rio Doce (CVRD) are presented and discussed, as well as the methodology to select steps and interpret results used at CVRD Technology Center (Sutec).

Jan 1, 1998

By A. D. Unsted

The Premier mine has been in existence for over 75 years and is closely woven into the glamour of the history of South Africa. A note on the geological formation of the diamond pipe and the gabbro gives a clearer overall picture of the mine. Mining methods for operations above and below the gabbro sill are briefly discussed. Ventilation arrangements for mining above the sill are briefly described and possible ventilation arrangements for mining below the sill are discussed in more detail. Note: conversions to S.I. units are not exact as rounding has been done.

Jan 1, 1980

By Wilhelm J. Kogelmann

The concept and operation of novel shaft sinking systems utilizing roadheader-type cutter booms, including mucking, conveying, and hoisting installations, are described. Selection criteria, performance data, and economic considerations for various shaft excavators are presented. Various applications of this low-cost and flexible system for civil engineering and mining projects will be discussed. The cutter booms can work in both soft ground and competent rock. Furthermore, the novel excavator can operate in ground stabilized by grouting, cementing, and freezing. The flexible cutting system can be used both for excavation of shafts, foundation pits, slopes, and for tunneling (drifting).

Jan 1, 1989