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By Robert Stefanko

A series of workshops were conducted -with invited participants from the coal mining industry to identify the most pressing research and development needs of the industry. Six workshops were held on the following subjects; Research Priorities for Mining-Oriented Universities, R&D Needs-for Surface Coal Mining, R&D Needs for Deep Coal Mining, R&D Needs for Anthracite Coal Mining, R&D Needs for Coal Mine Health and Safety, and R&D Needs far Environmental Control in Coal Mining.

Jan 1, 1975

By Jean-Sébastien Lambert, Joseph Kabuya, Richard Simon

Managing a highwall failure risk in an open pit mine by controlling and mitigating the impact of vibrations produced by blasting operations is key to achieving safe and cost-effective operations. The impetus behind this study was the risk of multiple bench failures in an open pit mine that was detected by Slope Stability Radar (SSR) following blasting at the foot of a highwall. The unstable high wall was over 140 meters(459.3 ft)high and 200 meters(656.2 ft)wide. The quantity of associated material was estimated at 3,000,000 metric tons(3,306,934 US tons). The overall slope angle was 44 degrees. In order to continue mining without causing the highwall to fail, this study was initiated as part of a risk management plan to mitigate this major risk by identifying mitigation measures related to blasting operations and assessing the response of the rock mass to each blast. Identifying blasting mitigation measures consisted of optimizing blasting parameters to avoid failure of the highwall. First, a signature hole operation was carried out to obtain seismic records that were georeferenced and associated with known single charges. The method used made it possible to determine the propagation velocity of the P-waves associated with the various lithologies studied and to calculate, from the geomechanical properties of the rock masses, the maximum peak particle velocities to be respected. Subsequently, the targeted area of operation was modelled with the I-Blast software in order to optimize the firing sequences to be used according to the different lithologies present. The model also made it possible to optimally predict the particle velocities associated with each blast and ensure compliance with the previously determined peak particle velocity limits. The assessment of the rock mass’s response using SSR consisted of defining alarm thresholds and an intervention plan for various possible alarms as well as quantifying the damage to the highwall from blasting. Controlling the impact of blast vibrations on the highwall’s stability was successful, as the mitigation measures used during mining did not accelerate the highwall’s movement. No upward trend in the stabilization time of the rock mass was observed by the SSR after each blast. Post-blast geotechnical inspections and analysis of post-blast deformations in the highwall also did not reveal significant damage to the highwall as a direct consequence of the blasting.

By G. Lyman

The cross-belt sampler is a device that is very widely used even though it has not been ratified by the Standards associations. This paper is concerned with the bias testing of two cross-belt sampler designs against stopped belt samples and a cross-stream cutter at the belt end. The bias analysis is carried out using size distribution as the analyte and conventional t-testing and the Hotelling T squared test, which are compared for their effectiveness. The paper considers the issue of detectable bias and the statistical planning of bias tests.

Jan 1, 2010

By R. O. Burt, D. J. Ottley

"SYNOPSISRecent developments in the use of the Bartles-Mozley table and the Bartles CTS screen are described for the gravity preconcentration of fine heavy mineral and metal particles present in low grade pulps. The B-M table is a relatively new device used for the recovery of particles of up to 100 micron size down to 5 microns or in the case of gold and platinum, down to 1 micron. The CTS screen is a wet screening device used for feed preparation ahead of the Bartles-Mozley table and will size effectively down to about 300 mesh. Results and operating data for a number of different materials are given including outline flowsheets; the effects of the major variables on the performance of the table are briefly discussed. The potential of the B-M table to treat a variety of different ores, coal, tailings, and waste products are considered. The utilization of the B-M table in association with other unit processes to improve overall results as well as to improve the economics of design and performance of plants are also mentioned.INTRODUCTIONA number of new gravity concentration devices have been developed in recent years for the recovery of fine heavy mineral and metal particles but for reasons which include low capacity, high capital or operating costs, competition from other and better processes, the absence of simplicity or reliability in operation etc., only a few which include the Bartles-Mozley table, have been proved to be of commercial application.The name of the machine is derived from the inventors name, Richard Mozley, who developed the B-M table at the University of Bristol in England. The table was subsequently taken up and patented, world-wide, by the National Research Development Corporation a British government agency. An exclusive license to manufacture the table was granted by NRDC to Bartles (Carn Brea) Ltd. in Cornwall, England."

Jan 1, 1973

By Elaine Araújo

Since the ancient times, clays were used as decolorant material for various types of oils. These clays were called ?decolorant clay?. They have the property to decolor dye materials present in mineral oils, plants and animals. Biofuel is a fuel derived from biomass of live organisms. As biodiesel is produced from renewable sources, the generation of employment due to industrial scale production may cause a reduction in the dependence on foreign diesel importing, as well as the reduction of air pollution by the addition of biodiesel to diesel. This study aimed to develop a technological process to decolor post- consumption oil to be applied as biofuel. The results were characterized by techniques of XRD (X-ray diffraction), X-ray fluorescence and FTIR (Fourier Transform Infrared). It was observed that the post-consumption oils presented a higher decoloration result after treatment with the Brazilian clay.

Jan 1, 2009

By James M. Harrington, A. Azra Bilgin, JoAnn Silverstein

The prevention of AMD in situ is more attractive compared to subsequent downgradient treatment alternatives that do not involve source control. AMD source control can be achieved by shifting the microbial activity in the sulfidic rock from pyrite oxidation to anaerobic heterotrophic activity. This is achieved by adding biodegradable organic carbon amendments to the sulfidic rock. This technique was applied in an abandoned mine pool with a pH of 3-3.5. Following treatment, near-neutral pH and decreased effluent heavy metal concentrations were achieved. In situ bioremediation by enhancement of bacterial iron and sulfate reduction is a promising technology for AMD prevention.

Jan 1, 2005

By Marcel Vallee, Fernand Dubuc

"The St-Honoré carbonatite complex, located 8 miles north of Chicoutimi, Quebec, was discovered in September 1967 as abnormal radioactivity was detected in the course of SOQUEM's aerial surveys. The complex, covered by a shallow layer of Trenton limestone, has been explored by aeromagnetic, ground gravimetric and magnetic surveys, and 12,013 feet of diamond drilling. Its age, from potassium-argon dating, is 650 million years. The carbonatite is approximately kidney-shaped and has a surface area of 6 square miles, 20 per cent of which is explored. It shows a central core of coarse-grained massive dolomitic carbonatite and an outer ring of foliated dolomitic carbonatite.The exploration work to date has resulted in the discovery, in the foliated carbonatite, of an incompletely drilled niobium (columbium) zone of pyrochlore-bearing carbonatite, at least 1,000 by 800 feet in size. This zone contains 5,000 tons per vertical foot grading 0.86 per cent Nb205 or at least 15,000 tons per vertical foot grading 0.66 per cent Nb205 or 45,000 tons grading 0.48 per cent Nb20s. The pyrochlore contains an average of 64 per cent Nb,Os. The central core contains a zone of rare-earth-bearing carbonatite (as monazite), grading up to 4.5 per cent rare-earth oxide, 3,500 ppm zinc and 290 ppm molybdenum. Stocks of nepheline syenite and magnetite diorite accompany the carbonatite. The total analysis and trace-element contents of typical rocks are presented."

Jan 1, 1970

By Melvin I. Esrig

Lime Cement column stabilization of soft clay and sand in Salt Lake City, Utah and in San Francisco California is described and discussed. Stabilization permitted the construction, in a single stage, of a 14 m MSE wall on "medium" clay in Salt Lake City. It was used to mitigate the potential for liquefaction in San Francisco and to stabilize the Young Bay Mud beneath the BART extension to San Francisco Airport. These applications are described and the field measurements of performance are reported.

Jan 1, 2000

By A. Rejeb, A. Millard

ABSTRACT: An evaluation of the importance of the thermo-hydro-mechanical couplings (THM) on the performance assessment of a deep underground storage design has been made as part of the international DECOVALEX III project. It is a numerical study that simulates a generic repository configuration in the near field in a granite medium. The thermo-hydro-mechanical evolution of the whole configuration is simulated over a period of 100 years. The model used to represent the unsaturated behaviour of the various porous media makes allowance for moisture transfers through the effect of thermal and water gradients. The paper presents a comparison of the temperature, water pressure and stress fields obtained by TM, TH, HM and THM coupled calculations. The results demonstrate that temperature is hardly affected by the couplings. In contrast the influence of the couplings on the mechanical stresses is considerable. This is attributed to the key role that water has on bentonite swelling or shrinkage effects that are dependent on its saturation level variations. KEY WORDS: Modelling, thermo-hydro-mechanical couplings, temperature, pressure, stress. ZUSAMMENFASSUNG : Im Rahmen des internationalen Projekts DECOVALEX III wurde untersucht, wie groß der Einfluss thermisch-hydraulisch-mechanischer Kopplungen (THM) auf die Leistungsfähigkeit eines Konzeptes zur Lagerung hoch radioaktiver Abfälle zu bewerten ist. Bei dieser numerischen Behandlung wird eine generelle Lagerungskonfiguration in granitartigem Milieu simuliert. Die thermisch-hydraulisch-mechanischen Prozesse werden für eine Dauer von 100 Jahren simuliert. Bei dem Modell, mit dem das Verhalten der verschiedenen, unterschiedlich porösen Milieus in ungesättigtem Zustand dargestellt werden soll, werden die Feuchtigkeitstransporte infolge thermischer und hydraulischer Vorgänge berücksichtigt. Verglichen werden in diesem Artikel verschiedene Temperatur-, Wasserdruck- und Beanspruchungsfelder, die sich aus TM-, TH-, HM- und THM gekoppelten Berechnungen ergaben. Dabei stellte sich heraus, dass die Temperatur nur gering von den Kopplungen berührt wird. Die Einflüsse der Kopplungen auf die Mechanik sind hingegen bedeutend; ausschlaggebend dafür ist der Faktor Wasser, der den Bentonit je nach Sättigungsgrad quellen oder trocknen lässt. SCHLÜSSELWÖRTER: Modellbildung, thermisch-hydraulisch-mechanische Kopplungen, Temperatur, Druck, Beanspruchung. RESUME : Dans le cadre du projet international DECOVALEX III, une évaluation de l’importance des couplages thermo-hydro-mécaniques (THM) sur les performances d’un concept de stockage de déchets fortement radioactifs a été menée. Il s’agit d’une étude numérique simulant une configuration générique de stockage en champ proche dans un milieu granitique. L’évolution thermo-hydro-mécanique de l’ensemble est simulée sur une période de 100 ans. Le modèle utilisé pour représenter le comportement non saturé des différents milieux poreux prend en compte les transferts d’humidité sous l’effet de gradients thermiques et hydriques. L'article présente une comparaison des champs de température, de pression d’eau et de contraintes obtenues par des calculs couplés TM, TH, HM et THM. Les résultats montrent que la température est peu affectée par les couplages. En revanche, l’incidence des couplages sur la mécanique est importante; ce qui est attribué au rôle majeur joué par l’eau à travers les effets de gonflement ou de retrait de la bentonite selon la variation de son degré de saturation. MOTS-CLEFS : modélisation, couplages thermo-hydro-mécanique, température, pression, contrainte.

Jan 1, 2003

By By Staff

"Acid mine drainage can be controlled by water treatment, retardation of the pyrite oxidation reaction system, or enhanced prediction that allows preventive action to be taken. The Bureau of Mines is conducting research in each of these areas; the results of this research are summarized in the eight papers that comprise this volume. Field work to evaluate overburden analysis, alkaline injection, and bactericidal control of acid formation is described, along with two new inexpensive methods to treat acid mine water. These papers were prepared for an acid mine drainage technology transfer meeting held in Pittsburgh, PA, on April 3 and 4, 1985. INTRODUCTIONAcid drainage from coal mines is one of the most persistent industrial pollution problems in the United States. Over 5,000 miles of streams and rivers are adversely affected, primarily by underground mines that have been abandoned for decades. Meanwhile, at active mining operations and at sites where mining occurred after 1977, discharge water must be treated to meet fairly stringent regulatory limits--at a cost to the industry of over $1 million per day.The Bureau of Mines has a special responsibility to facilitate integration of mining and mineral processing with environmental safeguards. This responsibility is twofold: the development of techniques to reduce or eliminate environmental degradation, and the improvement of existing pollution control processes to make them more efficient and more cost effective. Research in acid mine drainage exemplifies the Bureau's concern for these environmental aspects of mining.This collection of papers summarizes much of the Bureau's recent research on acid mine drainage and will give the reader a sense of where the research is headed, in addition to providing details regarding new technology and recently acquired knowledge. The research papers address four basic objectives:"

Jan 1, 1985

By Ken Dyck, Chuck Edwards

"Cameco's McArthur River is the world's largest high grade uranium mine. Production started in late 1999. Cameco carried out the engineering design and construction management for the McArthur River project, including all aspects of mining, ore handling and ore transportation. The ore composition was expected to vary dramatically (0 to 30% U3O8; 0 to 25% clay; etc). To cope with the composition swings, sizing screens were selected to provide classification in the grinding circuit. The grinding circuit started up close to the design to provide minus 500 micron slurry. The 50% solids (wt) ground ore slurry proved to be difficult to transport to and process at the Key Lake Mill. Slurry containing high concentrations of high density pitchblende (about spgr 8.0) and low concentration of stabilizing clays, would settle in containers. Ore transport efficiency to Key Lake was found to be unacceptable.A test classification cyclone was installed in the grinding circuit at McArthur River early in 2002. The cyclone operating parameters were not typical, but the cyclone was made to work very successfully. Transportation efficiency to Key Lake increased due to more stable slurry. Preferentially ground (fine) pitchblende particles were easier to leach at Key Lake. The radiation exposure for operators and maintenance personnel to handle the more stable slurry was also reduced.The classification sizing screens were removed from the McArthur River grinding circuit and replaced by permanent classification cyclones late in 2002.INTRODUCTIONThe McArthur River mine and Key Lake mill operations are located in northern Saskatchewan, approximately 650 and 720 kilometres from Saskatoon, respectively. Figure 1 is a location map. McArthur River is the world's largest, high-grade uranium mine, with a production capacity of 18.7 million pounds U3O8 annually. (Rosner and Edwards 1998, Dyck 2000, Jamrozek 2000, Rodgers 2001) Proven and probable reserves are more than 473 million pounds U3O8. McArthur River ore, grading on average 21% U3O8, is milled at Cameco's Key Lake operation, 80 kilometres southwest by road. McArthur River production began in December 1999."

Jan 1, 2004

By R. E. Head

[Surveys of the manganese situation conducted by the Geological Survey any other agencies have definitely established the, fact that the tonnage of high-grade manganese or in the United States is relatively small. It is therefore obvious that large-scale production of manganese is possible only through beneficiation of low-grade material. Deposits of low-grade manganese ore are being examined by engineers of the Mining Division of the Bureau of Mines to determine their size and possibilities as sources of manganese on a tonnage basis. The Metallurgical Division of the Bureau is developing and perfecting beneficiation processes with the objective of utilizing such low-grade ores. Microscopic study of these ores represents one phase of the research.]

Jan 1, 1941

By R. E. Head

[Surveys of the manganese situation conducted by the Geological Survey and other agencies have distinctly established the fact that the tonnage of high- grade manganese ore in the United States is relatively small. It is therefore obvious that large-scale production of manganese is possible only through beneficiation of low-grade material. ]

Jan 1, 1941

By G. B. Harris

It has long been appreciated that chloride chemistry has a number of advantages over the more traditional sulphate route for both extracting and separating metals. Modern materials of construction, coupled with the development of a more cost-effective and efficient hydrochloric acid regeneration technology mean that chloride-based processes are now more competitive and attractive. Such processing routes are able to recover more of the contained metal values in a feed, including iron in a benign and/or marketable form, and particularly the so-called rare and rare-earth elements which are increasing in demand in our electronic age. These factors, therefore, add appreciably both to the overall economics of a project, but also offer a much more sustainable approach to our dwindling natural resources. Additionally, chloride-based flowsheets can be much more environmentally-friendly, offering practical alternatives to two of the biggest headaches faced by the industry, namely cyanide usage and the generation of red muds. This paper presents a brief theoretical background, focusing on the latest developments of ferrous iron oxidation and the low-temperature, selective hydrochloric acid regeneration process, which is the key unit operation for any chloride flowsheet, and discusses in general the advantages of the chloride approach. Several recently-developed flowsheets, which have been tested at the miniplant level, are presented for gold, base metals, titaniferous magnetites and lead-silver ores wherein the advantages of considering a chloride approach are highlighted.

Jan 1, 2014

By P. Varona, L. Lorig, M. Board, E. Chacon

Geomechanical factors at the mine are important and will become even more relevant as the pit expands and deepens. To address these demands a team was assembled to collect geomechanical information and perform numerical analysis. The west wall is the largest and flattest of all the design sectors in the pit and rigorous studies were carried out on this wall. The wall behaviour is controlled mainly by a set of steeply dipping joints within the slope in the Fortuna Granodiorite and a weak zone, the Zona Plastica, that extends vertically near the pit bottom. These features lead to large toppling displacements in the upper portions of the wall. Two numerical models were used to reproduce the general features of failure observed in the wall. The modelling indicated that a toppling mode of failure results from shear on the steeply dipping joints. The toppling leads to slumping or landslides whereby the west wall flows slowly downslope as the Zona Plastica compresses

Apr 1, 1996

By Grant R. Brown

The report provides guidance for determining those environmental impacts associated with the surface mining of steeply pitching coal seams. In addition to the environmental impacts, four additional issues are addressed, namely (1) Time and motion studies of those coal mining systems employed in mining seams which pitch in excess of 25°, (2) Assessment of those mining techniques, (3) Development of rationale for the mining methods employed, (4) Identification of the reclamation practices and determine whether these practices were in compliance with appropriate Federal and State regulations. Five surface mines located in three geologically distinct basins of the United States were analyzed during the period of August through November 1979. The three basins include the Hanna Basin of Wyoming, the North Park Basin of Colorado and the Southern Anthracite Field of Pennsylvania.

Jan 1, 1980

By E. G. King

As low-temperature heat-capacity and entropy data were available for only one sesquisulfide (cerium sesquisulfide), it appeared desirable to augment the information for this class of compounds by measuring the sulfides of antimony and indium. In addition a pressing need existed for data on indium sulfide to supplement vaporization studies in progress in the Department of Mineral Technology, University of California. This Bureau of Mines paper reports low-temperature heat-capacity measurements and entropy evaluations at 298.15° R. of antimony sesquisulfide of stoiehiometric composition (Sb2S3) and of indium sesquisulfide which was somewhat deficient in sulfur (In2S2.93). The data for the latter substance were adjusted to correspond to the stoichiome tric composition (In2S3 ) . Indium sesquisulfide has a lower entropy at 298.15' K, than either antimony sesquisulfide or cerium sesquisulfide, in line with the higher atomic density of the indium compound.

Jan 1, 1962

By J. M. Ortiz

Grade control and short-term planning are usually based on the samples obtained from blastholes. These samples may carry a large sampling and sample preparation error. At El Tesoro copper mine in northern Chile, an advance drilling grid is used for short-term planning and grade control. These drill holes are sampled well in advance, and a short-term model that incorporates several variables and sophisticated estimation methods can be prepared for decisionmaking. An additional advantage of the advance drilling samples is that reverse circulation can be used instead of conventional down-the-hole equipment, and a very careful sampling and sample preparation process can be implemented, reducing the total sampling error. Advance drilling can be performed on a wider grid than blasthole drilling, hence the decision about the grid requires assessing the economic benefit of different sampling grids. Furthermore, this process allows the cost of poor sampling and the effect of different estimation procedures to be quantified. We demonstrate the optimization of the drilling grid for short-term planning and grade control at El Tesoro mine by means of the economic evaluation of the performance of different drilling grids, with different drilling techniques (which differ in the sampling error). The methodology is based on creating dense (exhaustive) geostatistical simulations of the grade distribution over a volume defined for a production period in respect of the geological model, and assuming each simulation as the true grade distribution. Then, samples are obtained from the exhaustive simulations at a spacing similar to the advance grid to be evaluated, and a sampling error is added. The short-term estimation procedures used on the mine are applied to determine the destination of each block and the profit obtained. This profit can be compared with the maximum profit (unachievable) and with the profit under different sampling errors and grids. The results show that the current 8 x 8 m drilling grid is appropriate and by reducing the sampling error, misclassification is also reduced, leading to an increase in profit of about US$ 5 million in 4 years.

Jan 1, 2012

By S R. La Brooy, T Giraudo, I C. Ritchie

The treatment plant at the Macraes Gold Project in New Zealand processes a carbonaceous, refractory sulphide gold ore. Since its commissioning in 1990, there has been a programme of continuous improvement of the plant, leading to higher recovery, increased throughput and low operating costs. During this time, a number of processes for treating both, or either, the preg-robbing carbonaceous fraction of the ore and the refractory sulfide fraction have been evaluated, trialed and utilised. The latest phase involves the installation by Minproc of plant utilising Newmont Gold's Pressure Oxidation Technology, a process which is anticipated to mitigate both problem factors when commissioned in 1999.

Jan 1, 1998

By B. Anderson, P. Churak, S. Dewar, A. Johnson, P. Eger

Although vegetation can be successfully established on fine taconite tailings, innovative approaches are needed to reclaim the coarse tailings used for dam construction. Through a series of cooperative projects with various government agencies and industries, EVTAC has been able to develop a unique closure plan. This plan will not only meet current reclamation standards, but also provide mitigation for a disturbed wetland and possibly create a tree plantation in the interior of the basin. By using waste products and exchanging materials, reclamation of the entire basin will be accomplised in a cost effective manner.

Jan 1, 2002