Search Documents

By D. Fleury

"This paper describes the challenges of mining a sill pillar under various types of paste backfill quality. From 1994 to 2002, Louvicourt mine produced approximately 12,600,000 t grading 3.5% Cu, 1.5% Zn, 27 g/mt Ag, and 0.85 g/mt Au. The mining method is transverse blasthole stoping, mining primary and secondary stopes. The production of this 4,300 t/d operation was accomplished using two mining horizons; from the 655 m level to the 415 m level and from the 860 m level to the 680 m level. The main sill pillar is between the 680 m level and the 655 m level. The second sill pillar is between the 885 m level and the 860 m level representing a quarter of the main sill pillar in size. Since 2002, production has gradually decreased and mining activities are expected to end in mid-2005. The sill pillar production will represent almost 25% of the total mine production. The overall recovery of the sill pillars stopes will be discussed in this paper. To recover the sill pillars, more than 1,500 m of development was planned in or under paste backfill. The first sill pillar stopes under paste backfill were mined out in 2002 with excellent results."

Jan 1, 2005

By Thomas J. Albin

U.S. Bureau of Mines research has found that maintenance of surface mining equipment is involved in slightly more than one-third (34.1 pct) of all surface mining accidents. Two groups of machines, haulage trucks and power shovels, accounted for over one-half of all surface mining mobile equipment maintenance accidents in 1978-84. Maintenance work-time histories for these machines were compared with accident records to identify the most hazardous-to-maintain systems within the machines. Recommendations to reduce the accident risk associated with maintenance of these hazardous systems are presented.

Jan 1, 1990

By John E. Tilton

During the past several years — much to the delight of producing firms and countries — copper prices have surged from under $1 to more than $3/lb. Anyone familiar with the industry also knows that since the early 1970s the long-run trend in real copper prices has been significantly downward. This sharp contrast between short-run and long-run trends raises the issue of the forces behind these developments. What has been driving short-run prices up and long-run prices down? Simple economics suggests that it is all a matter of supply and demand. When demand is rising faster than supply, prices will rise and vice versa.

Jan 1, 2006

By H. L. Gilbert

Improvements in production of high-purity chromium metal by magnesium reduction of anhydrous chlorides and by hydrogen treatment of electrolytic chromium are reported. Hydrogen-treated chromium has been arc-melted, and the arc-melted material has been successfully forged, rolled, and swaged. The material also has been forged at liquid-air temperatures. X-ray and metallographic studies indicate the recrystallization temperature of rolled chromium sheet to be about 750° C. Preliminary investigation of hot-bending characteristics of rolled chromium sheet shows the minimum bending temperature to be about 325° C. The heat resistance of chromium has been investigated.

Jan 1, 1952

By W. T. Wertman

A research program to aid development of better and more efficient methods for producing petroleum and increasing its ultimate recovery from underground formations is an integral part of the work of the Bureau of Mines on conservation of the Nation's natural resources. Economic, efficient production of recoverable oil and gas from a reservoir depends to a great extent upon the best and most accurate information that can be obtained from a study of the reservoir rock and its fluid contents. Information on oil and water saturation is pertinent and essential in wildcat, extension, and pool wells for good reservoir operations and prediction of performance. This report presents results of an investigation by the Bureau of Mines of core recovery and degree of drilling-fluid contamination occurring during cable-tool coring operations using oil-base mud. Representative core samples were obtained from 6 major oil-producing sands in 8 fields of West Virginia, Pennsylvania, and New York. Field-mixed, oil-base drilling mud was used for the first coring test, and lightweight, premixed oil-base mud, with an organic chloride tracer added, was used in coring eight other wells. Tracer analyses were made to determine contamination of core by drilling-fluid filtrate. Core analyses, including oil and water content and minimum interstitial water-saturation tests, were made on selected core samples to compare and evaluate water saturations determined by the two methods.

Jan 1, 1958

By BUREAU OF MINES

This report is submitted in accordance with provisions of the Synthetic Liquid Fuels Act of April 5, 1944 (30 U. S. C. 321-325, as amended), which require that: "The Secretary of the Interior shall render to Congress on or before the first day of January of each year a report on all operations under this Act." Owing to the broad scope of the content and the diversity of interests represented, the Annual Report for 1954 has been divided into two separate publications. Each is being published by the Bureau of Mines as a Report of Investigations, and the respective titles follow: R. I. 5118, Part I - R. I. 5119, Part II - 011 From Coal. 011 From 011 Shale. The introduction, identical in both reports, summarizes research progress in 1954 under the entire Synthetic Liquid Fuels program. A free copy of either publication may be obtained by writing to the Bureau of Mines, Publications Distribution Sec- tion, 4800 Forbes Street, Pittsburgh 13, Pa. The R. I. number and title of the publication desired should be indicated.

Mar 1, 1955

By Stephen Tadolini

A unique circumstance created by monitoring a pre-driven longwall recovery room permitted measuring the stresses of a coal pillar throughout its entire life cycle in less than a week. A fender pillar, created in approximately the middle of a longwall panel at a depth of 650 ft, transformed from a solid barrier pillar - to a yielding pillar - to a residual pillar as 3 ft slices were methodically removed with the longwall shearer. The complete transformation, or life cycle, took place in less than 12 hours. The stresses were quickly transferred from the pillar onto the standing pumpable concrete supports and into the outby pillars. Roof to floor closure measurements, combined with the timing of the pillar behavior, provides a detailed look at the uncontrollable convergence of underground mine openings. Pillars remain the most important form of ?primary support? and understanding these life cycles is vital for safe and efficient mine design, in both room and pillar and longwall panel extractions.

Jan 1, 2007

By P. Mokwena

Paper written on project work carried out in partial fulfilment of BSc (Hons) in Chemical Engineering Diamond synthesis has attracted a great deal of interest because of its exceptional properties and various applications. In this study, the chemical catalytic vapour deposition (CCVD) method was used to synthesize diamond films using acetylene as carbon source and hydrogen as carrier gas at a temperature of 1000°C, and their thermodynamic stability was studied. Photographic analysis revealed that these products are diamond films, Ramman spectroscopy confirmed that they are graphitic while confocal laser scanning microscopic image analyses proved that these diamonds films have structural defects due to iron impurity from the catalyst precursor. The quantity of diamonds films produced is also proportional to the acetylene to hydrogen ratio but these films are larger in size at lower acetylene to hydrogen ratio. Thermogravimetric analyses showed that transformation of these materials begins at 25°C but could not be used to determine if a temperature range below 25°C exists. The stability of these CCVD-synthesized diamonds also increases below 25°C when stored at different temperatures.

Jan 1, 2007

By Gene F. ] [Faufaul

This contract was concerned with the design, development, fabrication and testing of an improved tamper-proof filter cassette assembly for use in the, collection and evaluation of dust particulates, primarily in mining areas. This report presents the design effort, fabrication and tenting of five- prototypre unit$ as well as the design and production of 1000 filter cassettes with sampling heads. This new improved filter cassette has been tested and approved by NIOSH as meeting the requirements specified in the contract.

Jan 1, 1978

By P. Zhang

A multiyear, comprehensive study of flotation reagents used in phosphate beneficiation was conducted. The study involved the evaluation of pure fatty acid compounds, comparison of various anionic collectors and testing of iso-acids. Various C12 to C22 fatty acids were tested as Florida phosphate collectors. The saturated fatty acids were found to be very poor collectors when using the standard conditioning procedure, whereas the unsaturated C16 to C22 fatty acids showed fair to good phosphate collecting ability. The C18 fatty acids oleic, impure oleic and linoleic and the C20 eicosenoic acid were shown to be the best phosphate collectors. The best flotation results were obtained using Liqro GA tall oil and oleic acid. Four isostearic/iso oleic acid type fatty acid collectors were compared with a commercial grade oleic acid and with Liqro GA tall oil as phosphate collectors using standard laboratory conditioning and flotation procedures. The most selective collector evaluated was Century 1108, a high isostearic acid-type reagent. However, it was concluded that this excellent-performing reagent was too expensive for commercial use. Overall, the most promising reagent was probably Century MO-5. This collector is essentially an iso-oleic acid/stearic acid mixture (not isostearic acid), and it costs much less. This program laid a sound foundation for developing single collector, all anionic flotation processes.

Jan 1, 2009

By Philippe Dumont

?Lay out of the tunnel section ?General ?Geology ?Tunnels methods ?Stations constraints ?Impacts on tunnels ?Design ?Programs

By Tobias Hansson

The quality of Lime Cement (L/C) columns is to a great extent dependent on the installation procedure. At a site in the south of Sweden, the client reported problems with the installed columns. To evaluate the operator and equipment dependent part of the installation, Hercules Grundläggning AB was appointed as a competitor to the site contractor. The purpose was to install a number of L/C columns with equal installation parameters for both contractors. A total of 65 test columns were installed in June 1999. The geology is a typical Swedish organic soil profile with a top layer of peat overlying gyttja and clay. Two different binders were used in the comparison; blast furnace slag with cement and lime with cement. After installation, the quality of the columns was monitored by penetration tests and a column sampler for extracting whole columns. The column penetration test were performed 28 and 134 days after installation and extraction 134 days after installation. Inspection and tests of the extracted columns showed that by using a fully computer controlled procedure, the contractor produces columns of superior quality and homogeneity.

Jan 1, 2000

By H. F. Niemand, C. J. Postma, P. L. Crouse

"SynopsisThe separation of zirconium and hafnium is essential in the nuclear industry, since zirconium alloys for this application require hafnium concentrations of less than 100 ppm. The separation is, however, very difficult due to the numerous similarities in the chemical and physical properties of these two elements.Traditional methods for separation of zirconium and hafnium rely predominantly on wet chemical techniques, e.g. solvent extraction. In contrast to the traditional aqueous chloride systems, the AMI zirconium metal process developed by Necsa focuses on dry fluoride-based processes. Dry processes have the advantage of producing much less hazardous chemical waste.In the proposed AMI process, separation is effected by selective sublimation of the two tetrafluorides in an inert atmosphere under controlled conditions, and subsequent selective desublimation. Estimates are made for the sublimation rates of the two tetrafluorides based on the equilibrium vapour pressures. A sublimation model, based on the sublimation rates, was developed to determine if the concept of separation by sublimation and subsequent desublimation is theoretically possible.IntroductionZirconium requires several purification steps to conform to nuclear-grade specifications. Little information is available on the sublimation separation of Zr and Hf compounds, especially in the fluoride form, the majority of which deals with sublimation under vacuum conditions. On the industrial scale, only vacuum sublimation of ZrF4 has been reported. No records were found for the sublimation of ZrF4 in an inert atmosphere. Information on the sublimation rate of ZrF4 or HfF4 in an inert atmosphere is also limited. The rate is assumed to be dependent on several factors, of which temperature, area, and composition are considered the most important."

Jan 1, 2015

By Lawrence Williamson, Randall J. Essex, David P. Field

As part of a $2.2 Billion bridge project that will link Indiana and Kentucky, an interchange project northeast of Louisville will require the mining of a 6-lane tunnel system about 2,000 ft long in order to cross beneath the historic Drumanard Estate. This paper will discuss preliminary engineering that has been undertaken to compare two-bore and three-bore layouts, the planning of an exploratory tunnel facility, and the potential for including a test chamber to investigate the ability of high capacity roadheaders to mine the 22,000 psi limestones.

Jan 1, 2005

This report, the third in an annual series, outlines recent trends and developments in the minerals industry. Discussed are new methods, equipment, techniques, and systems used to more, effectively extract and process minerals and fuels. Environmental considerations, reduced ore grades, and the related increased quantities of material handled were the dominent concerns of the minerals industry in 1972. Productivity increased in most mineral commodities as equipment became more mobile, versatile, and sophisticated. Increasingly, equipment designs incorporated health and safety features. There was considerable interest in the field of energy and in pollution-free metallurgy processes.

Jan 1, 1973

By D. Bienstock

As part of the development of the hot-carbonate scrubbing process by the Bureau of Mines, the corrosion rates of steel in boiling solutions of potassium carbonate saturated with carbon dioxide and hydrogen sulfide were determined, and the effectiveness of various inhibitors was evaluated by Bureau researchers. The highly corrosive solution of carbonate saturated with carbon dioxide can be inhibited with a 0.2-percent concentration of either potassium chromate or sodium metavanadate. Solutions of carbonate saturated with carbon dioxide and hydrogen sulfide are mildly corrosive, 0.01 inch per year. Complete absence of corrosion is obtained with 0.2 percent sodium metavanadate or 0.15 percent vanadium pentoxide. Oxidizing inhibitors such as potassium chromate are destroyed in the alkaline sulfide mixture, N-alkyl trimethylene diamines, at a concentration of 0.1 percent, lower the corrosion rate to about 0.005. Sodium metasilicate, at a concentration of 0.6 percent, completely inhibits the corrosion but may deposit free silica in the system. Commercial cladding materials such as the epoxy coatings also prevent corrosion.

Jan 1, 1962

By L. Yuan, A. Smith

In order to provide insights for the optimization of ventilation systems for U. S. underground coal mines facing both methane control and spontaneous combustion issues, a computational fluid dynamics (CFD) study was conducted to model the potential for spontaneous heating in longwall gob areas. A two longwall panel district using a bleeder ventilation system was simulated. The permeability and porosity profiles for the longwall gob were generated from a geotechnical model and were used as inputs for the CFD modeling. In this study the effect of methane emissions from the mined coal seam, including the longwall face and overlying rider seam reservoirs on the gob gas distribution was considered. The spontaneous heating is modeled as the low-temperature oxidation of coal in the gob using kinetic data obtained from previous laboratory-scale spontaneous combustion studies. Unsteady state simulations were conducted and the effects of the coal’s apparent activation energy and reaction surface area on the spontaneous heating process were also examined. Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

Jan 1, 2007

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 S-L. Weeber

Ash fusion temperature is the temperature at which the mineral matter in coal begins to soften, flow and fuse. It is an important parameter relating to coal utilization. Optimum ash fusion temperatures derived from coal in the Witbank Coalfield region are approximately 1400°C, and higher, although temperatures above1300°C may be deemed acceptable. This study attempted to determine which factors, mineralogical or inorganic-chemical, influence variations in the ash fusion temperatures in certain coals. Coal was sampled from the Number 2 coal seam at opencast and underground workings at New Clydesdale Colliery, Witbank Coalfield, South Africa. The samples represented known low and high ash fusion temperature coal. Analyses performed included proximate analyses, calorific value determination, percentage sulphur, ash fusion temperatures, ash analyses (composition of ash), X-ray diffraction, scanning electron microscopy and petrographic studies. Results show that although a complex relationship exists between ash fusion temperature and the various geological and coal parameters, some positive correlative results were obtained. These indicate a possible relationship between low ash fusion temperatures and i) finer size fractions, ii) an increase in iron content present in the form of pyrite and iii) the form in which pyrite is present, namely cleats. High ash fusion temperatures tend to correlate with i) the absence of pyrite or ii) pyrite present as framboids.

Jan 1, 2000

To George Orwell the year of 1984 was the inspiration for a book. To most New Zealanders it was the year that the fourth Labour Government was elected to power. It was also the year that the review of mining legislation commenced. While Orwell's book and the election of Labour are clearly events of some historic note, one could be excused for classifying the review of minerals legislation somewhat differently in terms of its present achievements! Since the review began it has led a tortuous path through a rapidly evolving policy environment to a point three years hence where no major policies have been determined.

Jan 1, 1987