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By Dziurzyn&apos, W. ski

This article outlines the results of a computer simulation reproducing the transport of a mixture of air and methane following the outburst on 25 November, 2005 in transport gallery D-6, bed 409/4, at the ?Zofiówka? hard coal mine. Based on a mathematical model, numerical method and boundary conditions from the disturbance caused by the outburst, the Ventgraph system of computer simulation programs was adopted for the study. We performed a computer simulation of the influence exerted by the outburst on the propagation of the air and methane mixture, and compared the results of this simulation with those of the actual event as registered by sensors of the mine monitoring system. A validation of the model allowed us to present temporal changes in the concentration of methane and air along flow routes. Keywords: mine ventilation, outburst of methane, numerical simulation, monitoring system.

Jan 1, 2008

By William E. Ford, Edward Salisbury Dana

Secondary Twinning. - When there is reason to believe that the twinning has been produced subsequently to the original formation of the crystal, or crystalline mass, as, for example, by pressure, it is said to be secondary. Thus the calcite grains of a crystalline limestone often show such secondary twinning lamella?. The same are occasionally observed (Ilc, 001) in pyroxene crystals. Further, the polysynthetic twinning of the triclinic feldspars is often secondary in origin. This subject is further discussed on a later page, where it is also explained that in certain cases twinning may be produced artificially in a crystal individual - e.g., in calcite (see Art. 282).

Jan 1, 1922

By J. -M. Rescoussier

Due to Important settlements inducing major structural damages, the western part of the Grand Littoral shopping centre has been closed in 1997. The present paper describes the project of underpinning including not only micropiles under the structure of the building but also a reinforcement of the soil located between the shopping centre and the edge of the embankment surrounding the western part of the shopping centre. The aim of this reinforcement is to reduce existing horizontal movements to allowable values.

Jan 1, 2002

By E. LaRocque

"Denison Mines Limited has been processing uranium ore in the Elliot Lake area since May of 1957. The ore body is located i11 the Huronion sediments on the north limb of the Quirke Lake syncline. Minerals of metallurgical significance are brannerite, uraninite and monazite. Gangue minerals include quartz, chlorite, sericite, pyrite, pyrrhotite and rutile. Silica content of the ore is greater than 75 % and pyrite-pyrrhotite content around 7 %. Specific gravity of the ore is 2.75.The Denison flowsheet is based on sulphuric acid leaching to extract the uranium values from the ore followed by liquid-solid separation to wash the uranium-bearing solution from the barren ore. The resultant pregnant solution is concentrated and purified by ion exchange followed by two-stage precipitation with ammonia to produce an ammonium yellow-cake.Elliot Lake ores require high acid concentrations and high temperatures to extract the uranium from brannerite and monazite. Uraninite will leach at low acid concentrations as long as oxiclizing conditions exist. The whole ore must be treated so that these conditions do exist.This paper provides a description of the leaching process equipment as originally installed and major changes in that equipment to date. Process control refinements to economically improve extraction are also discussed."

Jan 1, 1979

By F. D. Ayhan

The aim of this study was to investigate desulfurization and de-ashing of a mixture of subbituminous coal and gangue minerals by the agglomeration method. For this purpose, experimental studies were conducted on a mixture containing subbituminous coal, pyrite, quartz and calcite. The effects of some parameters that markedly influence the effectiveness of selective oil agglomeration, such as solid concentration, pH, bridging liquid type and concentration, and depressant type and amount, were investigated. Agglomeration results showed that the usage of various depressants (Na2SiO3, FeCI3, corn starch, wheat starch) in the agglomeration medium has a positive effect on the reduction of ash and total sulfur content of agglomerates. It was found that an agglomerate product containing 3.03% total sulfur and 25.01% ash with a total sulfur reduction of 56.71% was obtained from a feed that contained 7% total sulfur and 43.58% ash when FeCI3 was used in the agglomeration medium. Key words: Desulfurization, De-ashing, Agglomeration, Coal, Gangue minerals

Jan 1, 2009

By Gary B. Petersen

The author has developed a seven-step process called the Applied Rock Mechanics (ARM) Protocol that the author has used to solve numerous roof stability problems in mines throughout North America since 1975. It is a practical evaluation process using trained observation, innovative data collection instrumentation, video borehole cameras, analytical processes, and controlled testing methods that have become highly effective in solving ground control problems in every type of underground mine. This paper will describe each of the steps of the protocol and how the rock mechanics engineer applies them to resolve a typical ground control problem.

Jan 1, 2012

Water quality standards for some of the substances likely to be discharged to natural waters by the mining industry are discussed. After briefly examining how uses of water can be affected by discharges, standards for suspended solids and turbidity, pH, and toxic materials are considered. Heavy metals are examined in some detail because of recent public concern regarding their discharge. Caution is given in connection with their analysis at the very low concentrations required for management of natural waters. Finally, the issues of what constitutes a water right concentration compliance breach, and the appropriateness of biological monitoring as a condition on a water right are raised.

Jan 1, 1986

Executive A R LEDOUX, Chairman ARTHUR S DWIGHT CHARLES F RAND E P MATHEWSON J V W REYNDERS Membership E DEGOLYER, Chairman W Y WESTERVELT, Vice-chairman WILLIAM H BASSETT H G MOULTON C MINOT WELD Finance WALTER H ALDRIDGE, Chairman GEORGE D BARRON GALEN H CLEVENGER Library GEORGE C STONE,' Chairman JOHN H JANEWAY ALEXANDER C HUMPHREYS, ROBERT LINTON FREDERICK F SHARPLESS

Jan 1, 1923

Surface subsidence caused by coal mining operations was the subject of a very successful symposium organised by the Illawarra Branch of The Australasian Institute of Mining and Metallurgy in February, 1973. This symposium dealt with the principles of subsidence and overseas experiences arising out of underground mining. Since that time the New South Wales Department of Mineral Resources and Development (formerly the Department of Mines) has incorporated in the approval for pillar extraction certain conditions related to the monitoring of surface movement. Surveys and plans are required to be kept at mines where total or partial extraction of coal takes place. This paper traces the monitoring of surface movement in the Northern Coalfields of New South Wales over the past ten years. Reference is made to the National Coal Board's Subsidence Engineers' Handbook (1975) and how the guidelines expressed therein have been beneficial. Mining engineers in Australia are able to plan underground workings where minimum subsidence is allowable and are in a position to foreshadow the surface effects where total pillar extraction is carried out. In certain cases such surface effects can be minimised by structural design in buildings or pipelines.

Jan 1, 1980

Mining is an inherently risky business; from the technical, environmental, social, and economic uncertainties associated with advancing an exploration prospect to a viable project to the operating, market, and safety risks and uncertainties attached to a developed mine. Since we cannot totally escape the risk and uncertainty related to resource projects, as an industry we should improve our presentation of the upside and downside risks in the context of the project?s development path and maturity. More transparent, consistent, and balanced views of technical confidence will better inform both internal and external stakeholders about the expected risk in the project. International reporting codes set out the minimum standards, recommendations, and guidelines for public reporting of Exploration Results, Mineral Resources, and Mineral Reserves. However, the reporting code principles of transparency and materiality are largely subject to the interpretation of the competent person(s), which may introduce a degree of subjectivity in reporting, particularly the level of disclosure regarding supporting information. It is fundamental that Mineral Resources, Mineral Reserves, and study outcomes are reported so as to unambiguously present the level of inherent technical uncertainty (or confidence) in a project, while conveying a balanced view of the opportunities a project presents. Reporting needs to consider various stakeholders who may rely on this information, and present the data in the context of the changing risk profile associated with project development paths and project maturity. This paper discusses the interdependence of resource-to-reserve conversion, the consideration of various technical-economic study types, and the level of confidence conveyed to stakeholders relying on these technical reports and other company public announcements.

Jan 1, 2014

By H. Sekimoto, T. Matsuoka, K. Yasuhara, M. Ota, S. Akutagawa

A magnetic anisotropy sensor is used for nondestructive measurement of stress on surfaces of a ferromagnetic material, such as steel. The sensor is built on the principle of the magneto-strictive effect in which changes in magnetic permeability due to deformation of the material is measured in a nondestructive manner, which then can be translated into the absolute values of stresses existing on the surface. This technique was applied to measure stresses of H-beams used in tunnels. The results show that this method could be one of the promising technologies for non-destructive stress measurement for safe construction of underground structures. Une sonde magnétique anisotropique est utilisée pour des mesures non-destructives de stress sur la surface d' unmétal ferromagnétique, comme l'acier. La sonde est construite sur le principe de l'effet magnéto-strictif dans lequel les changements dans la perméabilité magnétique due à la déformation du metal est mesurée avec une manière non-destructive, qui peut être alors traduite en valeurs absolues des stress existants à la surface. Cette technique a été appliquée pour la mesure de stress des poutres en H utilisées dans les tunnels. Les résultats montrent que cette méthode peut être l'une des technologies promet tantes concernant les mesures non-destructives de stress pour des constructions sûres de strcutures souterraines. Ein magnetischer Anisotropie-Sensor wird für die zerstörungsfreie Messung von Spannungen an Oberflächenvon ferromagnetischen Materialien wie z.B. Stahl verwendet. Der Sensor kann Änderungen in der magnetischen Durchlässigkeit auf Grund von Verformungen des Materials erkennen, die dann in Absolutwerte der Spannungen an der Oberfläche umgerechnet werden können. Die Methode wurde auf Messung von Spannungenvon H-Balken in Tunnels angewendet. Ergebnisse zeigen, dass dies eine vielversprechende Methode für diezerstörungefreie Messung im Tiefbau ist.

Jan 1, 2003

By T. Dlokweni

Several Rockmass classification systems have been developed and used in Civil Engineering design and for underground mining operations. Some of these rockmass classification systems have been modified and used in the South African coal mining industry to quantify descriptive geological information for use in coal mine design and roof support selection. The Coal Mine Roof Rating (CMRR) system developed in the USA has been investigated in detail as part of the study. Advantages and disadvantages of the system have been identified by means of underground and surface borehole testing. Investigations into the rating systems in South Africa found that most of the rating systems used in the South African coal mining industry are for planning purposes, and are conducted on borehole cores. This study also highlighted that the rating systems being used are based on geology, and that the human factor plays a major role in the rating systems. To overcome these problems, all the classification systems used in South African coal mines have been benchmarked against impact splitting technique and documented. The best elements of these systems are combined into a new standard system that will be easily used by all mine geologists and rock mechanics engineers. Plusieurs systèmes de classification de la masse rocheuse ont été développés et utilisés dans le Génie Civil et pour les opérations d'exploitation minière souterraine. Certains de ces systèmes de classification de la masse rocheuse ont été modifiés et utilisés dans l'industrie minière sud-africaine pour quantifier l'information géologique descriptive utilisée dans la conception de mines de charbon et la sélection de soutènement du toit. Le système d'Evaluation de Toit de Mine de Charbon (CMRR) développé aux USA a été examiné en détail, comme part de l'étude présente. Tests en surface de trous de mine ont permis d'identifier les avantages et inconvénients du système. Une étude des systèmes d'évaluation en Afrique du Sud a révélé que la plupart des systèmes d'évaluation utilisés dans l'industrie minière sud-africaine sont utilisés pour la planification, et sont menés sur les carottes de trous de mine. L'étude présente a aussi souligné que les systèmes d'évaluation utilisés sont basés sur la géologie, et que le facteur humain joue un rôle majeur dans les systèmes d'évaluation. Pour surmonter ces problèmes, tous les systèmes de classification utilisés en Afrique du Sud ont été référencés en termes de technique de fissuration sur choc, et documentés. Les meilleurs éléments de ces systèmes sont combinés dans un nouveau système standard qui sera utilisé aisément par tous les géologues de mine et les ingénieurs miniers. Verschiedene Gesteinsmassenklassifikationssysteme wurden entwickelt und kamen im Design für Hoch- und Tiefbau und Untertageabbau zum Einsatz. Einige dieser Gesteinsmassen-klassifikationssysteme wurden modifiziert und sind in der südafrikanischen Kohlebergbauindustrie in Verwendung, um beschreibende geologische Informationen für die Anwendung im Design von Kohlebergwerken und der Firstabstützungsauswahl quantitativ zu beschreiben. Das in den USA entwickelte Kohlengrubenfirstbewertungssystem (CMRR) wurde als Teil der Studie im Detail untersucht. Vorteile und Nachteile des Systems sind mittels der Untergrund- und Oberflächenbohrlochprüfung gekennzeichnet worden. Prüfungen der Bewertungssysteme in Südafrika ergaben, daß die meisten Bewertungssysteme die in der südafrikanischen Kohlebergbauindustrie benutzt werden, Planungszwecken dienen und werden anhand von Bohrlochkernen durchgeführt. Diese Studie hob auch hervor, daß die verwendeten Bewertungssysteme auf Geologie basieren und daß der menschliche Faktor eine Hauptrolle in den Bewertungssystemen spielt. Um diese Probleme zu überwinden, wurden alle in südafrikanischen Kohlengruben benutzte Klassifizierungssysteme vergleichsweise in Hinblick auf Spaltschlagtechnik überprüft und dokumentiert. Die besten Elemente dieser Systeme werden in ein neues Standardsystem kombiniert, das leicht von allen Grubengeologen und von Gebirgsmechanikingenieuren benutzt werden kann.

Jan 1, 2003

By Tim O’Neil

What prompted the merger of the two long-established American Mining Congress/National Coal Association (AMC/NCA) groups that combine the coal, hard-rock, industrial- and agricultural-minerals sectors of mining? Both associations have been facing similar stresses for several years - structural changes in their respective industries, the changing personality and role of government and well-financed and organized opposition groups. In 1993, the AMC board of directors undertook efforts at reorganizing the association. One board member, who serves on both boards, suggested it might be time to give serious consideration to merging the organizations. This is an idea that had been discussed more or less informally at least three times during my tenure at NCA. Negotiations toward a merger began after that and were consummated in February of this year.

Jan 1, 1995

By Norman O. Lotter, Dominic Fragomeni, Lori J. Kormos, Guy Comeau, Antonio Di Feo

"A performance opportunity was identified for the Raglan concentrator operation by changing the selection of xanthate from Potassium Amyl Xanthate (PAX) to Potassium Isobutyl Xanthate (PIBX). This opportunity was identified by a Statistical Benchmark Survey of the operation and QEMSCAN measurement of these survey samples, in which fine liberated pentlandite was found in the final tailings. This was confirmed by some laboratory scale flotation testwork using High- Confidence Flotation Testing. A statistically designed plant trial was implemented in 2007 to measure and confirm the performance gain. This trial design used on-off switching following a three-month reference distribution of normal operations using PAX. This layout provided both external and internal reference distributions on PAX to be established. These were used to evaluate the internal reference distributions on PIBX. This trial format was deliberately designed so as to block out the effects of autocorrelation in the operations data. In this way, small but significant metal recovery gains may be measured and proven in a plant trial. The paper describes the case study to show that this approach successfully blocks out autocorrelation in time, which is an obstacle in analysing concentrator operations data. The results showed that the PIBX had produced clear and statistically significant recovery gains for Ni, Cu, Pt and Pd. Adjusted for feed and concentrate grades, these recovery gains were: Ni: 1.00, Cu: 0.96, Pt: 5.07 and Pd: 1.90%.INTRODUCTIONConcentrator OperationsMilling and flotation, sometimes accompanied by gravity separation, are well-established unit processes. These have traditionally been used to treat ore that has been mined, producing a lowbulk concentrate containing a high percentage of the paymetal(s) in the ore mined. These concentrates are more economically treated in subsequent beneficiation processes than the ore from which they were produced.This choice of a concentration process results in a significant and variable paymetal loss to the concentrator tailing. This tailing is discarded and disposed of in an impoundment area, and has no immediate business use. This paymetal loss forms the largest loss of paymetal in the entire flowsheet by which refined, or saleable, metal(s) are produced [Cramer, 2001]. The question arises as to whether any particular concentrator is performing at its full potential, and how this answer may be determined. In a concentrator operation, there is always an ongoing performance improvement programme for this reason."

Jan 1, 2009

By Dave Bulled, Khiratt Husain

"The use of High Pressure Grinding Rolls is gaining significant interest as a replacement for SAG milling in the comminution of hard rock ores because of the potential for reduced costs in terms of energy and grinding ball consumption. Estimation of expected energy consumption for fullscale operations has conventionally involved the testing of a few fairly large samples in pilot scale HPGRs. This paper describes the development of a small-scale batch test method for determining a work index for HPGR of a large number of samples that can be used to show the variability of the ore as an integral part of a geometallurgical approach to circuit design and production forecasting.The test equipment that was developed comprises a hydraulic press with adjustable pressure operating on small batches of ore in a locked cycle test procedure. A work index measurement was determined that links the specific energy consumed in the test to the breakage achieved such that the index can be used to predict comminution energy requirements.The measurements were calibrated against laboratory scale HPGR equipment to develop a model for design and forecasting that includes crushers, HPGRs and ball mills in a complete comminution circuit.INTRODUCTIONEstimation of the expected energy consumption for full-scale HPGR operations has conventionally involved the testing of a few fairly large samples in laboratory and pilot scale machines (Danilkewich, 2006). With the financial input of five mining corporations, SGS Lakefield Research has developed a small scale test capable of providing relevant information on the variability of energy consumption and size reduction from drill core samples. It is our intention that the values measured in the test will be scaled up, through benchmark comparison with pilot sized and full sized HPGR units, to allow plant design and throughput forecast on a block by block basis of the mine plan using a new CEET program. CEET® (an acronym for Comminution Economic Evaluation Tool) is an advanced grinding design and performance predicting tool that uses energy relationships to model the performance of SAG / Ball mill circuits."

Jan 1, 2008

By W. Blake, J. Whyatt

Sixty years of rockbursting in the Coeur d’Alene district has taught painful lessons and led to a number of practical advances in controlling rockburst hazards. This paper summarizes those lessons, concentrating on practical measures that have been successfully adopted to reduce hazards. These lessons are explained in the context of district mining history and current understanding of rockburst phenomena. Overall, the paper provides the practicing mine engineer with an appreciation of rockburst hazards and an overview of practical measures that can be used to control these hazards in the context of Coeur d’Alene district experience.

Jan 1, 2002

By M. J. Nicol

Mr Vegter has analysed, in some depth, the approximations made in the treatment of the kinetic data presented in the original by ourselves (ref.1) and has come to the conclusion that ?under the experimental conditions used by Adams and Nicol (1986) the steady-state assumption was inaccurate?. We are acutely aware of the fact that the experimental method adopted does not permit the attainment of a true steady-state in the elution reactor. However, this does not eliminate the attainment of a pseudo steady-state by a suitable choice of the experimental parameters with the accompanying simplification of the analysis of the data with the aim of drawing the reader?s attention to the most important objective of the paper viz. the effect of various operating parameters on the rate of elution of gold.

Jan 1, 1997

By T. A. Ngcobo

Paper written on project work carried out in partial fulfilment of BSc Eng (Mining)degree The purpose of this report is to assess the risks faced by mines in dolomitic compartments in particular Kloof 8 shaft. The dolomites of the West Rand comprise one of South Africa?s most natural water resources, and overlie the reefs of the richest gold mines in the world. The pumping of water from the dolomitic aquifers to prevent flooding has caused the natural water table to subside, and the resulting cavities within the dolomite rock formations that overlie many gold deposits sometimes collapse, causing sinkholes. These impacts of the mining industry could worsen over time if preventative measures are not taken. This report discusses these impacts in detail, more specifically the risks to which operations in dolomitic compartments are exposed. A risk analysis was carried out to access the risks that the organization could face and it was this analysis that allowed one to examine the best methods to combat the problems. Other factors such as geological features and seismic events were also considered for the evaluation. To aid with the completion of this work various resources were utilized. A literature study was undertaken, information was gathered from various experts who specialize in dolomitic studies, evaluations were conducted and conclusions reached. The results from the project indicated that preventative measures should be implemented and correct procedures put in place to prevent any disasters.

Jan 1, 2006

By F. M. McEvoy, E. J. Steadman, R. Murfin

In England, the provision of aggregate is determined by the historical relationship between construction and aggregate consumption. This approach does not necessarily lead to sustainable decision-making and can be seen as being driven by political expediency, rather than reasonable environmental consideration. The introduction of the statutory requirement for Strategic Environmental Assessment (SEA) in the UK has provided the opportunity to examine this issue on a more rational basis. This paper provides a practical application of a SEA based approach, to the provision of aggregates at a regional level. The process, underpinned by relevant information on resources and environmental assets, suggests that alternative supply scenarios for aggregate provision are tested in a transparent, consistent manner with increased genuine stakeholder consultation. It supports a move away from "predict and provide" approaches to one where aggregates are sourced with the best balance of environmental costs and benefits.

Jan 1, 2005

Media Type Effect on Grinding Efficiency

Sep 13, 2010