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By R. L. F. Kay, T. A. Fletcher, A. J. Boyce, C. M. Rice

Paper presented at Mineralisation in the Caledonides, the Mike Gallagher memorial meeting held in Edinburgh, 27-28 June 1996. The synorogenic, mafic Ordovician intrusion comprises orthopyroxene-rich xenoliths and mafic-ultramafic cumulates with low-grade pyrrhotite, chalcopyrite and pentlandite mineralisation. Despite abundant textural, mineralogical and O isotope evidence for significant assimilation of country rocks, S isotopes indicate only a modest uptake and suggest that mineralisation is dominated by magmatic sulphur. The preferred explanantion is that the magma was close to S saturation on emplacement. Uptake of elements such as Si and O led to early crystallisation of orthopyroxene, resorption of olivine and early segregation of a sulphide liquid. Post-magmatic interaction with a high-temperature, surface-derived fluid, whose movement may have been controlled by regional shear zones, reset biotite and whole-rock O isotope values but not those of orthopyroxene. This model identifies the presence of olivine-rich rocks and evidence of extensive assimilation as guides to prospectivity

Jun 19, 1905

This study estimates costs of producing bituminous coal and lignite by strip-mining methods in 12 hypothetical mines. Basic costs are developed by geographic area, rank of coal, and output capacity. Seam thickness and depth and type of overburden are considered typical for the area in which the hypothetical mine would be located. The cost analyses are based on the use of new equipment, the prevailing union wage scales, and the payment of all miscellaneous costs including royalties, contributions to the miners' welfare fund, and license and permit fees. All model mines are considered to have a life span of 20 years. Capital costs of bituminous strip mines with a capacity of 1 million tons per year range from $12.7 million in the Appalachian region to $16.0 million in the Interior province. The corresponding selling price, assuming a discounted cash flow return of 12 percent on investment, is $5.40 and $6.95 per ton, respectively. For bituminous coal strip mines producing 3 million tons annually, a capital investment of $24.9 million will render a selling price of, $3.46 per ton in the Interior province, whereas a similar mine in the Appalachian region requires a capital investment of $28.0 million to produce coal selling for $4.01 per ton. Subbituminous strip mines of 5 million tons of output per year range in capital costs from $28.7 million in the Southwest to $13.9 million in Wyoming and Montana. Coal produced in the Southwest would sell for $3.03 per ton, while coal from Wyoming and Montana would sell for $1.83 and $1.64 per ton, respectively. The capital costs for the strip mining of lignite range from $6.4 million for an output capacity of 1 million tons annually to $20.7 million for an annual capacity of 5 million tons. The corresponding selling prices of $3.01 and $2.12 per ton, respectively, Indicate the advantages of a large-capacity strip mine.

Jan 1, 1972

By Robert G. Lenz

Control of ground water for construction purposes is an everyday occurrence in the U.S. Thousands of pumps are in service at any given time. Most of these applications simply consist of pumping water out of an excavation, generally with the aid of sumps. Modern hydraulic and electric submersible pumps permit these procedures because of their ability to pump solids and take air without losing their prime. These procedures work fine up to a point and permit the contractor to control his ground water problems adequately and at minimal cost. When that point is exceeded, the ground water problems sometimes are compounded. Over-application of open pumping techniques can result in slope failures, cofferdam instability, bottom heaving, boils, loss of ground, damage to adjacent structures and utilities, and assorted other maladys which could and should be avoided. This paper will deal with the options involved in ground water control, a discussion of the unwanted side effects of dewatering, and examples of ground water control projects in various cities around the U.S.

Jan 1, 1988

By Ernest J. Conway

This report presents engineering drawings for six material handling devices for underground coal mines. The devices were designed under a U.S. Bureau of Mines program to reduce injuries from material handling during mine and equipment maintenance. The six devices are (1) scoop-mounted 1411: boom, (2) swing-arm boom, (3) heavy-component lift-transport, (4) mine mud cart, (5) container-workstation vehicle, and (6) timber car. Each device is described briefly, and recommendations are made concerning the design of new devices.

Jan 1, 1989

By Manqiu Xu, Songtao Yang, Zongfu Dai, Robert Pelton, Carla Abarca

"Fine mineral particles are difficult to process by flotation because of their low collision efficiencies with air bubbles. Decreasing air bubble size and increasing mineral particle size through flocculation are the most common approaches to improve flotation efficiencies. Herein we demonstrate that nanoparticle flotation collectors can be engineered to selectively induce fine mineral particle aggregation and promote flotation.Flotation tests of clean fine pentlandite (Pn) and Clarabelle Mill (CBM) rock tails and pyrrhotite (Po) tails that contained significant amount of fine pentlandite have confirmed that the nanoparticles can serve as both collectors and selective flocculants for fine pentlandite. In the case of clean fine Pn, the nanoparticle collectors virtually can float almost all Pn fines. Scoping tests on CBM tails have shown significant improvement in nickel recovery. Addition of nanoparticles as a flotation aid can recover 20% of the nickel contained in the rock tails and 40% of the Pn contained in the Po tails compared to current mill operations giving 0% nickel recovery from rock tails and no Pn selectivity from Po tails. Ongoing work includes attempts to identify optimal strategies for employing nanoparticles in fines flotation.IntroductionFine particle flotation is an industry-wide challenge in mineral processing. Fine mineral particles are difficult to process by flotation because fine particles have low mass and thus low momentum, which results in their low collision efficiency with air bubbles (Dai, Fornasiero, & Ralston, 1999). In addition, fine particles have not only high specific surface area but also more active surface area, which causes high reagent consumption. For base metal sulphide minerals, particle size between 10 µm and 70 µm is a typical range where high flotation recoveries can be achieved with conventional flotation chemistry and acceptable cell residence times. For pentlandite, the flotation recoveries decrease sharply when the particle size is below 10 µm and hydraulic entrainment is the dominant mechanism, giving recoveries proportional to water recovery and no Pn enrichment. (Jameson, Nguyen, & Ata, 2007)"

Jan 1, 2015

By D. R. Brox, J. Levell

The Montana Tunnels Mine was mined out to a depth of 900 feet at the end of 1999. The first signs of instability were recognized in 1996 along the upper slope area of the northwest sector when the pit was mined out to a depth of approximately 500 feet. To extend the life of mining operations, it has been proposed to extend and steepen the northwest highwall to a depth of 1000 feet. Slope stability analyses were carried out using the UDEC software program to assess the stability and deformation of the proposed highwall design. Back analysis of an instability in 1997 along the upper slope section and highwall deformation to date has indicated reasonable agreement with the observed mode of failure and displacement monitoring results. The results of detailed analyses of the proposed highwall design have indicated very limited additional deformation, further development of tension cracks is unlikely and large-scale instability is not expected to occur. A total of 40% of additional mining has been completed and ongoing displacement monitoring to date has confirmed very limited additional movement and no further tension crack development.

Jan 1, 2001

By Kay E. Goldberg

The Bureau of Mines conducted a study to develop and evaluate a training workshop for mine safety training personnel. The workshop was based on the Instructional Development Institute (IDI) which has been used for nearly ten years to train educators and administrators in the application of a nine-step model for defining, developing, and evaluating instruction. The Mining Instructional Development Institute (MIDI) was developed by investigators at the University of Southern California as a two-phase project. Phase I involved the modification of the six-day IDI program (including audiovisual presentations, workbooks, games, and exercises) for use by mine safety trainers as a workshop lasting three and one-half days. Phase II involved the evaluation and validation of the prototype MIDI workshop by means of a two-stage jury of experts and a prototype field trial. On the basis of data collected in the validation process it was determined that the institute provided an effective and useful method of instruction in mine safety training and that the institute would be especially valuable for mine safety training administrators and supervisors.

Jan 1, 1980

By F. A. Jones

Increased mechanization .of coal mines has emphasized the need for study of actual power requirements of the various machines employed in the production of coal and losses in the distribution of power to these machines. These studies are being made in order that hazards, excessive use of power, and high maintenance cost of equipment resulting from these losses may be analyzed and eliminated where possible. Research on the use of electric power in-coal mines was suggested by the Advisory Committee of the Bureau of Mines in 1937, and it was decided to begin with a study of individual machines of various types under operating conditions in modern coal mines. The transmission of power, particularly line losses and inadequate return circuits, should be a part of the investigation. This report presents some of the data of an initial study in commercial mines. ACKNOWLEDGMENTS The superintendents, engineers, and other officials of the two mines studied cooperated fully and aided in setting up and transporting the test equipment, giving such information as was requested.

Jan 1, 1942

By J. A. L. Napier

It has been established that significant time-dependent stope convergence may occur over time periods of hours and days in certain hard-rock gold and platinum mines. The source of this time-dependent behaviour appears to be associated with both pre-existing discontinuities and with mining-induced fractures that form near the stope face. These induced fractures may be associated with blasting processes and may also be formed in response to high stress concentrations in the unmined regions immediately ahead of the stope face. In shallower platinum mining operations, time-dependent behaviour is, however, observed to be much less marked unless some form of specific mining-induced fracturing occurs. One particular case of considerable interest is the time-dependent behaviour that is found to be associated with the formation and deployment of crush pillars. The purpose of the paper is to present a simple limit-equilibrium computational model of this behaviour that is sensitive to both the formation sequence and the size of planned crush pillars in a mine layout. This model provides a useful means to optimize the sizing of crush pillars, and at the same time may be used to identify potentially hazardous circumstances in which pillars may not crush in a stable manner.

Jan 1, 2012

By Eder Salazar

El presente texto describe la optimización de la productividad en la empresa minera a través de la mejora contínua en la cadena de valor en SMEBSAA, los siete pasos de la calidad, proceso de mina, planta, soporte y la cuantiificación de dicha mejora en la cadena de valor en SMEBSAA. Asimismo, la implementación de los diversos sistemas de gestión refuerzan los resultados, siendo el Sistema de costeo basado en actividades el gran agrupador de toda la información de los módulos: Logístico, Control Patrimonial, Orden de Servicio, Planillas y Contabilidad.

Sep 12, 2005

As the chief field of the gold dredging industry in Otago is the district traversed by the Molyneux River (called above Cromwell the Clutha) and its tributaries, a brief reference to the geology of that region and the origin of its alluvial gold will not be out of place. The prevailing rocks are metamorphic schists, chiefly mica and quartz schists, pr.obably of Silurian age. Though these rocks do not contain many payable quartz reefs, gold appears to be distributed in small quantities all through them,chiefly associated with the quartz lamime and lenses. The river drift, however, contains numerous pebbles of quartzite, quartzoze conglomerate, and fme-grained slate. Seeing that these rocks are hardly known to occur in situ within the watershedof the Molyneux River, though Devonian and carboniferous rocks of similar character occur to the north-east and south-west, it seems probable that the schists were at one time overlaid by carboniferous and Devonian rocks, and that these have been removed by denuding agencies. Be this as it may, it is certain that the schists themselves have been greatly eroded by the action both of water and of ice, and that the resulting drifts have themselves, in many cases, been sorted and re-assorted by the same agents.Consequently the drifts are very varied in character and often developed on a grand scale. In geological age they vary from Early Tertiary (though some may be older) to Recent.

Jan 1, 1903

By R. D. Begley

This paper will present detailed design drawings of a flexible single floor residential superstructure proposed for both longwall and room and pillar mining conditions. All efforts were made to provide an immediately available economical alter- native for future home builders on subsidence prone land. Based on this fact, a basement was not included in the design because additional costs and measures would be required to minimize cracking and leakage. A cost comparison with a traditional superstructure demonstrated that this would be a cost effective alternative. The criteria used to determine the design of the residential structure was as follows: 1. The appearance should not be different then a typical three bedroom residence; 2. Only commercially available devices and present architectural and engineering technology should be used to achieve the required "flexibility" of the super- structure; 3. The structure as completed would be capable of resisting a predetermined amount of vertical and horizontal movement; and 4. If the structure was to experience stresses beyond its capabilities, it could be easily removed from the foundation and releveled.

Jan 1, 1986

By M. O. Serbousek

To further investigate the potential of precast concrete sets as a support medium for underground mines, the Bureau of Mines designed an eight-piece precast reinforced concrete drift set for a small opening. Twenty-two sets of three different member sizes were tested to destruction under two loading conditions. A discussion of the test results and typical failure patterns is presented.

Jan 1, 1969

By M J. Kindley

The Golden Cross Gold Mine Project is now fully operational and into its second year of operation. Because of its location in the sensitive Coromandel Peninsula , strict water management and environmental requirements had to be met. This led to the development of new technologies for cyanide recovery and the adoption of advanced water management and water treatment systems. This paper discusses the water management and treatment system adopted for contaminated water at Golden Cross and provides data on the operational history to date.

Jan 1, 1993

By Mike Ounpuu

"Locked cycle testing has become more common practice in the last 10 years. Reasons vary from a desire to avoid pilot plant testing, demand for more variability testing within deposits, and perhaps most importantly, a request from the financial institutions who invariably finance many of the projects. Surprisingly, many people don’t understand locked cycle testing, analysis and balancing. This paper provides a brief overview of locked cycle testing, and then progresses into a more detailed discussion on the analysis and balancing of locked cycle test data. The paper endeavors to educate CMP personnel on how to determine if the test was good and if a reasonable metallurgical projection was made. The paper uses case studies to illustrate the key points.INTRODUCTIONA locked cycle test is a repetitive batch used to simulate a continuous circuit. The basic procedure has a complete batch test performed in the first cycle which is then followed by similar batch tests which have “intermediate” material from the previous cycle added to the appropriate location in the current cycle. These batch tests, or cycles, are continued in this iterative manner for an arbitrary number of cycles. The final products from each cycle, i.e. final concentrate and final tailings, are filtered and thus removed from further processing. At the end of the test, all the products, final and intermediate, are dried, weighed and subjected to chemical analysis. The test is balanced and a metallurgical projection is made.This description can be found in many of our classical textbooks for the mineral engineer 1, 2, 3,4. Unfortunately, none of these textbooks provide any discussion beyond the basic procedure. Often, they provide comments such as in Taggart’ where he states; “It is questionable whether in any case it approximates mill results any more closely than the standard batch test”. It is truly surprising that our classic textbooks promote that locked cycle tests are more art than science, and suggest that they can be of dubious value. None of the textbooks provide meaningful insight or discussion in how to assess:"

Jan 1, 2001

By W. L. Cornell

The Missouri lead ores are the only domestic sources of cobalt presently being mined and processed for other materials. They represent the best short-term solution for meeting up to 13 pct of the Nation's strategic and critical cobalt needs from domestic sources. Presently, the cobalt is lost as an impurity in the copper, lead, and zinc concentrates and in the mill tailings because the technology to recover it with minium impact on present production does not exist. This paper presents results of research, built upon earlier Bureau of Mines laboratory research, to enumerate the problems encountered in cobalt recovery from the copper concentrate under actual mill conditions; to present alternative solutions to these problems; and finally, to describe the best available technology for cobalt recovery within the imposed constraints. Mineralogical analyses showed the cobalt present as a distinct mineral phase, predominately siegenite, amenable to a physical separation method such as froth flotation. Flotation was chosen for recovery because of easy adaptation by the mills. Unit processes of grinding, conditioning, and flotation were studied individually and in concert, and a series of continuous tests were run based on the parameters developed to obtain engineering data for subsequent economic analysis. Overall cobalt grades of 3.00 wt pct at a recovery of 64.0 pct were achieved.

Jan 1, 1987

With the exhaustion of orebodies close to the main haulage shaft of the Emperor mine, an increased rate of development, aimed at earlier investigation of values disclosed by exploration drill holes has been attained with an overall reduction in unit costs.This paper describes the techniques used in rates of advance up to and exceeding 1,000 ft per 28-day period.

Jan 1, 1966

By A. B. Hazar-Yoruç

Ferrochromium produced by smelting chromite ores is an important alloying component in the steel industry. Ore, coke and fluxes are mixed and reacted in an arc furnace for a smelting process of ferrochromium. In ad-dition to this process, pre-reduction of chromite ore with carbon is an important industrial process. In all these processes, the mechanism and kinetics of reduction of chromite with carbon play an important role. In this study, the reduction of Turkish chromite ore with carbon was investigated. Chromite and carbon were ground to three different particle size groups. Chromite was mixed with carbon in stoichiometric and excess ratios. The samples were reduced under argon atmosphere at temperatures between 1,200° and 1,350°C. The formed phases and alloy compositions of reduced chromite samples were analyzed by optical microscopy, scanning electron microscope (SEM) with EDAX and X-ray diffraction analysis (XRD). Experimental results showed that the degree of reduction and the reduction rate increased with increasing temperature and decreasing particle size. The highest degree of reduction, 61.4%, was obtained at 1,350°C. The reduction took place in three stages: Stage 1: transformation of Fe3+ to Fe2+ and formation of metallic nuclei, Stage 2: formation of metallic crust around the particles and Stage 3: growth of the metallic crust and coalescence of the metallic phase.

Jan 1, 2007

The recent paper by Bain (1981) contains an unfortunate, and potentially misleading typographic error. On page 9, second paragraph, Bain states that, "some samples of drill core from the (Candlow) Formation ... contain up to 90 ppm gold and 2 000 ppm arsenic". The gold value should read 90 ppb. In fact, in the original version of the paper (Bain, 1980), the gold value quoted was actually 60 ppb.Bain also refers briefly to some geochemical data which is attributed to me, and which I feel require some clarification.In addition, the paper contains some factual errors relating to the occurrence of carbonate and potential host rocks to Carlin-type gold deposits in the Candlow Formation.

Jan 1, 1981

By Felipe Calizaya

This study describes the principles involved in the design of a booster fan installation, the basic requirements, and the provisions needed to guarantee a safe operation of the unit. It also describes how a booster fan should be selected and what measures should be taken so that events such as uncontrolled recirculation of air in a mine can be avoided. A computer program called MFSELECT is presented to assist the ventilation engineer in the design process a For a given mine ventilation network, the program determines the duties of fans and regulators that will fulfill the airflow requirements of a mine and minimize the total power consumption. The application of the program is illustrated by the detailed solution of a sample problem. A Case Study based on the Jim Walter Resources' No. 7 Mine is utilized to describe the basic requirements for the design and operation of booster fans, and illustrate their potential benefits in mine ventilation. Finally, the study discusses a process control system designed to evaluate the safety conditions in the mine and report on the status of both surface fans and underground booster fans.

Jan 1, 1990