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By G. H. Schnakenberg

In 1986, the US Bureau of Mines (USBM) embarked on a major research effort to develop technology that could substantially reduce worker exposure to face hazards by simply relocating the equipment operators to an area of relative safety. This reduced-exposure mining system (REMS) research effort enhances the USBM's ongoing health and safety efforts aimed at reducing and controlling dust and noise and reducing accidents through training and better mining practices. This paper reports on the progress made on the developing research and demonstrates the technologies required for the computer-assisted teleremote operation of continuous mining machines, haulage systems and roof bolting machines.

Jan 1, 1998

By Michael G. Nelson, Dot J. Helm, Edmond C. Jr. Packee

Under a Section 319 Water Quality grant from the U. S. Environmental Protection Agency, a working group of government agencies, mining industry representatives, and University of Alaska researchers undertook reclamation of an abandoned mine site on Birch Creek, near mile 101 of the Steese Highway. Stream hydrology, water quality, and the extent and nature of natural revegetation, were measured before the site was then recontoured to decrease the bedload deposition and bank erosion of the streams. Methods for stabilization of streams and rivers appear to have much in common with those for locations further south, but are subject to complications unique to the North, such as the formation of aufeiss, and to a lack of accurate climatological data. Natural revegetation appears to be possible for most northern placer mine sites. However, it may take place more slowly than required by public perception. Preliminary data indicate a surprising lack of nutrients in the floodplains of mined areas. Natural revegetation may be enhanced by selective planting of grasses and willows, which will contribute variously to soil quality, bank stabilization, and short-term appearance. Monitoring of hydrologic and water quality data, and of natural and artificially placed vegetation will continue at the .Birch Creek site through the summer of 1995,

Jan 1, 1995

By R. J. Miller

The current US national commitment to expanding the human presence into the solar system will clearly require major facilities in Earth orbit or possibly on the Moon. Such facilities will need large amounts of materials for structural modules, life support, propulsion and shielding. The heavy transportation costs in fuel required to lift materials from the Earth's surface make a terrestrial-based space system inherently inefficient. A more cost-effective approach would be to provide as much of the required materials as possible from other bodies in space not having the high cost of Earth launch. This paper identifies potential targets for space-based resource utilization, constraints on exploitation and relative benefits of various sources.

Jan 1, 1994

By P. H. Lu, M. J. DeMarco, J. R. Koehler

Beginning in late 1985 and continuing through 1987, US Bureau of Mines personnel investigated longwall chain pillar and entry design in two and three-entry gateroad systems at a deep underground coal mine in central Utah. To evaluate their respective stability characteristics, four chain pillars and two longwall panels within the two separate entry systems were instrumented with Bureau hydraulic borehole pressure cells to continuously monitor vertical and horizontal pillar and panel stresses through adjacent panel retreat. In addition, supplemental entry closure information was obtained from sites located in the vicinity of the instrumented pillars. The findings presented in this report demonstrate the practicality of evaluating mine pillar stability using in situ methods and support three significant conclusions regarding ground control aspects of the investigated two-entry system: (1) Total areal entry loading was considerably less for the two-entry system, as opposed to the three-entry system, (2) a smaller percentage of opened ground in the two-entry system contributed to a marked reduction in rooffalls, and (3) lower areal loading in the two-entry system suggests improved ground conditions when mining the underlying seam.

Jan 1, 1987

By A. Geoffrion, L. J. Cousineau

In underground powerhouse excavations, the access to the horizontal sections of the penstocks is most often critical. Other factors which influence the schedule include: the sequences of excavation, the interface dates between contracts, the type of support for the overhead cranes and whether the roof in the powerhouse is a reinforced concrete arch or a suspended prefabricated material. At Outardes 3, Churchill Falls and LG-2, these factors, along with the size of the powerhouse and the local topgraphy and geology were studied to produce the optimum schedule.

Jan 1, 1983

By Lit-Mian Chan, David H. Carlson, John H. Johnson

This paper presents an apparatus and procedures to implement a methodology for controlling ambient air quality in a confined working environment, such as an underground mine, an underground storage area, or a tunnel. The air quality control methodology is directed at limiting the quantities of exhaust pollutants emitted by diesel-powered vehicles into the confined space by identifying vehicles that are excessive polluters. The methodology is based on tailpipe and ambient air measurements in the confined space, and the ambient air threshold limit values (TLVs) for the various diesel exhaust pollutants. The methodology consists of two computational methods; a deterioration criteria computational method to identify excessive polluting vehicles, and an engine performance computational method to determine engine performance and to provide information needed to diagnose engine faults. The methodology is designed for implementation in conjunction with a preventive maintenance program. The first part of the paper describes the mine air and tailpipe emissions measurement apparatus and techniques used to obtain data. This is followed by sections discussing the deterioration criteria and the engine performance computational methods. A section discussing some common engine emissions-related faults is also presented. Lastly, a proposed procedure to implement the methodology including a possible hierarchical structure for mine personnel involved to implement the procedures is presented.

Jan 1, 1993

By Dave Watson

Henderson Mine personnel have more than 20 years experience and have placed more than 400,000 m3 (520,000 cu yd) of shotcrete and concrete. Over the last 20 years, the mine has used a variety of equipment to place concrete, wet shotcrete and dry shotcrete and is constantly trying to cut costs and increase efficiencies. Recently, the mine received a state-of-the-art wet shotcrete placer. The batch plant was automated, and a mobile concrete-form jumbo was fabricated. The mine will also receive a new concrete transport truck. Henderson’s background The Henderson Mine is owned by Climax Molybdenum Co., a unit of Amax, Inc. It is an underground, primary molybdenum producer near Empire, CO. The mill is located between Silverthome and Kremmling, CO and is connected to the mine by 16 km (10 miles) of underground and 8 km (5 miles) of surface track. Except for the ore haulage system which is powered by overhead trolley, all mobile equipment is rubber-tired and diesel-powered.

Jan 1, 1992

By C. B. Alcock

The control of high temperature processes requires the ability to measure significant variables during operations. With increasing automatic computerized control there is need for sensors which can provide on-line chemical analyses of all phases present in a reactor without the necessity to withdraw samples from the high temperature reaction zone. Probes using electrochemical cells and conductivity measuring devices have provided the answers to some of these problems, notably the measurement of oxygen in liquid metals, and similar potential systems based on the same fundamental principles for the analysis of non-metallic and metallic elements appear feasible. In this discussion, the state-of-the-art in chemical sensors will be discussed in terms of the potential materials of construction, and, in some cases, the limitations of upper temperature at which some promising systems can, at present, be applied. It is concluded that a new phase of basic research could improve the outlook substantially by providing solutions for some problems in chemical sensors which are now well-defined.

Jan 1, 1990

By B. P. Atkin, D. W. Brown

A handleability monitor was designed to provide a simple, rapid, on-site assessment of the whole or part consignment of a coal blend in its "as-received" condition. The monitor was evaluated at a number of coalhandling plants, which handle both metallurgical and power station coals from a variety of sources worldwide. The results can be used to predict which coals could routinely pass through a handling plant at line capacity without causing blockage or delay. Despite extensive analysis of the data, it was not possible to correlate the handleability index to the regular sample analysis of moisture, ash and size analyses of the coal blends.

Jan 1, 2002

By Bruno Paponetti, Luigi Toro, Carlo Abbruzzese, Maria Y. Duarte, Anna Marabini

A bioleaching process has been developed to extract manganese from low grade domestic resources not amenable to conventional mineral processing operations. Between the different strains of microrganisms tested, Thiobacillus ferrooxidans has appeared poor over manganese, Aspergillus niger allowed to obtain high recovery, probably due to the metabolic production of citric and oxalic acids, showing a remarkable complexing and reducing action. The growth of microflora has been correlated to the MnO dissolution as confirmed by SEM observation.

Jan 1, 1989

By Nora M. Hutt, Kevin A. Morin

One technique for controlling ongoing acidic drainage is to relocate and submerge net-acid-generating waste rock in a lake or water-retaining impoundment. This can lead to the overall improvement of water quality and the reduction In short-term environmental liabilities. A case study of this technique is the Eskay Creek Mine in northern British Columbia. Some findings of the study are: (1) the addition of lime to each truckload of rock, based on its rinse pH, neutralized the accumulated acidity and suppressed the accumulated-metal release, (2) only 10-20% of the dump's neutralization potential had been consumed when acidic drainage appeared, (3) water chemistry in the watershed recovered roughly three years after relocation, and (4) environmental liability was reduced due to the cessation of on-land acidic drainage with no degradation of lake chemistry.

Jan 1, 2000

By M. Mohammed, S. J. Jung

The prime criteria in the design of underground openings with complicated geological structures is ground control. Stability of underground openings for deep mines is critical because incorrect orientation or geometry of the shaft, stopes and accessways often results in the failure of openings due to high stress conditions. Current design procedures for complicated orientation and geometry of mines are rapidly becoming inadequate. In this study, the finite element method (ANSYS) has been used with optimization criteria to design safer, more stable underground openings.

Jan 1, 1995

By J. D. Miller, D. M. Catarious, F. L. Stanley

The quality of cleaned products from coal preparation plants is often variable due to natural fluctuations in the washability characteristics of the plant feed. To combat this problem, many modern plants have installed on-line analyzers that provide feedback for the real-time control of product quality via the adjustment of circuit cutpoints. Unfortunately, optimization studies show that this approach may actually lead to increased losses of saleable coal. This paper discusses the problems associated with the real-time manipulation of circuit cutpoints and suggests alternative modes of operation that are better suited for plant optimization. A case study involving an eastern U.S. coal plant has been used to compare the economic impacts of these different approaches for plantwide control.

Jan 1, 2000

By A. R. Laplante

In this paper, the performance of the Knelson Concentrator and of the batch and continuous Falcon Concentrators are compared. The units are based on different operating principles, and perform quite differently. The Knelson yields very high free gold recoveries over a wide size range of both the recovered and rejected species. It is less effective in recovering very fine (<15 μm) or very flaky gold, as encountered in flotation feeds, concentrates or tails. It is the preferred unit for gold recovery from grinding circuits. The batch Falcon is effective in the fine range, typically less than 37 μm for gold. Its recovery zone is quickly saturated when there is significant heavies in the feed. It works best as a pre-concentration unit, or when sulphide content is low. The continuous Falcon is a versatile unit which is capable of recovering fine heavies (density down to 5 g/cm 3), especially from coarser gangue.

Jan 1, 1993

By M. G. Ayat, J. Dasher

Having an interest in coal slurry pipelines from a decade of arguments with Ed Wasp and crew at Bechtel about pumping thicker slurries slower, I immediately read this article and found nothing in it pertinant to the title. Ayat and Scott pumped five unidentified coals at 9% solids (50%-60% is the area of interest) in a 25-mm (1-in.) pipe around two square elbows through a 76-mm (3-in.) cyclone for up to 60 minutes and sized a large number of samples of unstated size on an unidentified wet screening device. They did not measure power consumption, discharge pressure, flow rate, or give pump tip speed or impeller diameter. They siad the cyclone had a "high" pressure drop (unmeasured) and did much of the degradation (measured) but more or less per unit of energy expended? Hargrove was not measured, so there are no data as to whether it would correlate with degradation. The authors conclude, with no attempt, correlation is "hard to establish." Please experiment before concluding. I am at a loss to know what "increasingly smaller size" means, much less what theory says such particles take "exponentially larger quantities of energy," which the authors neglected to measure. If such experiments without pertinent data or justified conclusions must be published, please attach a pertinant title.

Jan 1, 1990

By F. M. Doyle, Jun Li, Milton E. Wadsworth, Ximeng Zhu, E. Peters

The electrochemical behavior of pyrite in borate/sulfate solutions was investigated using cyclic voltammetry. Three anodic peaks at approximately -0.8 V, -0.1 V and +0.5 V (SCE) were detected along with their corresponding reduction peaks. The first two peaks correspond to the oxidation of surface products. The third peak corresponds to the direct oxidation of pyrite with reaction products FeO oxides. sulfate ion and partially oxidized sulfur intermediates present as a surface film of polysulfides and So. The Few oxides and sulfur intermediates were reduced to ferrous hydroxide and HS during the negative-going scan. The HS interacted preferentially with Fe(OH), on the surface to form FeS. Excess fenous hydroxide continued to reduce to metallic iron. During the return positive-going scan, metallic iron was oxidized to ferrous hydroxide and FeS was oxidized to pyrite. These reactions are characterized by a unique double peak observed in the region -0.8 to -0.65 V. The growth kinetics of the surface sulfur film formed during anodic oxidation were studied using chronoarnperomeay. Potentiostatic measurements were well correlated by a paralinear rate equation, suggesting the formation of an intermediate passive film, associated with the simultaneous dissolution of the outer layer of the film. The reaction rates were affected by applied potential, solution pH and temperature, but were independent of electrode rotation speed. A reaction kinetics model which fitted well with experimental results, was developed.

Jan 1, 1993

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 G. Johnston, P. K. Chatterjee, S. Holguin

M. Gershon The article is an excellent one, providing a basis for the conduct of the major tasks in underground mine planning and scheduling. I object to only one word. Since that word is featured in the title, it is a strong objection. The word used erroneously is optimization. There is no optimization performed in the article. By definition, an optimization is an approach that yields the best of all possible solutions. We can limit this definition to its narrowest sense, the optimization techniques of operations research such as linear programming, or broaden it to include less sophisticated search procedures that find the best mine plan or schedule. No such claim is made in the article. No optimization of any kind is performed. The major tool used is a simulation, which, in truth, is probably more appropriate for this problem than any optimization. But simulation does not optimize. It only allows for quick evaluation of many options, leading to the selection of the best plan "of those tried," not "of all possible plans." This article, of course, is not the first mining paper to make this error. It seems that the word optimization is used more to impress people than to refer to any act of optimizing. It is used in a way that implies "try to optimize"or "come close to optimize," but not to really do it. It is usually appropriate to quietly ignore this error. But when Dr. Chatterjee, who has done so much good work in true optimization projects and whose work I have come to admire, makes such an error, it is time to publicly dispute it. Having discussed this very point with him in the past, I am sure that he will agree. If he can support this position in his response, perhaps people will start to listen and we can reduce the number of false claims of optimization. This should be easy for him in this case since the approach he used, simulation, is the more appropriate one anyway.

Jan 8, 1988

By William F. Kane, Eric C. Drumm

Rock slope failures in the Great Smoky Mountains of Tennessee are a continuing problem. A study of the geotechnical factors affecting such slopes was conducted in this geologically complex region. Seven rock slopes, five of which had undergone failure, were identified and mapped. Other parameters were mapped in addition to the standard geologic and geometric parameters. These were joint frequencies across and down the slope, and surface hardness from Schmidt hammer tests. Regression analysis on the various data revealed that Schmidt hammer hardness correlates very well with joint cohesion back-calculated from failure geometries. This approach suggests an alternative means for estimating joint strength.

Jan 1, 1986

ICMM’s vision is ‘a viable mining, minerals and metals industry that is widely recognised as essential for modern living and a key contributor to sustainable development’. The ICMM Sustainable Development Framework provides the basis for achieving this vision by assisting the industry to improve its performance. Two years on from the first SDIMI conference, significant progress has been made in further developing and implementing the Framework. To fulfill their commitment to implement and report performance against the ten sustainable development principles in the Framework, ICMM’s corporate members have committed to report ‘in accordance’ with the GRI 2002 Sustainability Reporting Guidelines and the Mining and Metals Sector Supplement, developed by the GRI and ICMM. While much remains to be done, development of the Supplement and the commitment to reporting mark an important milestone for ICMM and the sector.

Jan 1, 2005