Search Documents

By G. W. Bonnell, D. A. Young, D. G. Genter

Through 1996 and 1997, CANMET and the Cape Breton Development Corporation (CBDC) conducted a project to study the Phalen Mine’s 7 East longwall ventilation network to help determine methane emission patterns that were having a negative impact on coal production. Increased methane emissions were primarily related to mining depth and were also affected by the influence of a large sandstone body located above the worked seam. The research included the installation of tube bundle systems to monitor waste (gob) methane and pressure differentials. The focus of this paper is on the novel use of tracer gas techniques that helped shed light on the performance of the ventilation system and in determining the methane migration paths in the waste.

Jan 1, 2001

By P. H. S. W. Kulatilake, B. Malama

To simulate brittle rocks, a mixture of glastone, sand and water was used as a model material. Thin galvanized sheets were used to create joints in blocks made out of the model material. To investigate the failure modes and strength, both the intact material blocks as well as jointed model material blocks of size 35.6 × 17.8 × 2.5 cm having different joint geometry configurations were subjected to uniaxial and biaxial compressive loadings. Results obtained from the intact model material blocks are used to validate a new intact rock failure criterion for biaxial loading. Results obtained from both the intact and jointed model material blocks are used to develop a strongly non-linear new rock mass failure criterion for biaxial loading. In this failure criterion, the fracture tensor component is used to incorporate the directional effect of fracture geometry system on jointed block strength. The failure criterion shows the important role the intermediate principal stress plays on rock mass strength. Zur Simulation spröder Gesteinsarten wurde ein Modellmaterial aus Dentalgips, Sand und Wasser hergestellt. Daraus wurden Blöcke gegossen, in denen mittels dünnen, galvanisierten Blechen Trennflächen erzeugt wurden. Die Blöcke mit Abmessungen von 35.6 × 17.8 × 2.5 cm wurden in einaxialen und biaxialen Druckversuchen belastet. Es wurde das Versagensverhalten und die Festigkeit von intakten Blöcken sowie durchtrennten Blöcken mit unterschiedlicher Trennflächengeometrie untersucht. Aus den Ergebnissen der Versuche an intaktem Material wurde ein neues Versagenskriterium für biaxiale Belastungen validiert. Die Ergebnisse der Versuche an intakten und durchtrennten Blöcken wurden verwendet, um ein neues stark nicht-lineares Versagenskriterium für geklüftetes Gebirge unter biaxialer Belastung abzuleiten. Darin wird der Bruchtensor verwendet, um den Einfluss der Trennflächengeometrie auf die Festigkeit zu erfassen. Das Versagenskriterium stellt heraus, welche Bedeutung die mittlere Hauptspannung für die Gebirgsfestigkeit hat. Un mélange de platre dentaire, de sable et d’eau a été utilisé pour développer un matériau analogue des roches fragiles. De fines feuilles galvanisées permettent de créer des discontinuités représentatives des discontinuités naturelles dans des bloques fabriqués avec ce matériau analogue. Les modes de rupture et la résistance, tant pour le matériau intact que pour le matériau avec ses discontinuités, ont été étudiés sur des blocs de 35.6 × 17.8 × 2.5 cm soumis à des efforts de compression uniaxiaux et biaxiaux. Différentes configurations de géométrie de discontinuités ont été considérées. Les résultats obtenus à partir des blocs intacts permettent de vérifier un nouveau critère de rupture pour les roches intactes soumises à des efforts biaxiaux. Les résultats obtenus, tant avec les blocs intacts qu’avec les blocs avec discontinuités, sont utilisés pour développer un nouveau critère de rupture, fortement non linéaire, pour les massifs rocheux soumis à des chargements biaxiaux. Dans ce critère de rupture, un tenseur de fractures est introduit pour caractériser les effets directionnels de la géométrie des systèmes de discontinuité sur la résistance des blocs avec discontinuités. Ce critère de rupture démontre le rôle important de la contrainte principale intermédiaire sur la résistance des massifs rocheux.

Jan 1, 2003

Detailed characteristics of gold from Pliocene auriferous quartz gravels from Waimumu (Southland) have been studied using a combination of optical microscopy, energy dispersive microprobe analysis and scanning electron microscopy techniques. The gold at Waimumu is classified as either: 1. detrital gold, or 2. irregular gold. A number of different morphologies a recognisable within each 'gold type'. Evidence is given for an predominently authigenic origin for some of the gold at Waimumu.

Jan 1, 1987

By Juan Carlos Salas

In this paper, a collaborative R&D model which has been successfully applied by a global mining companies association is presented and analysed both from the conceptual and practical point of view and an example of these collaborative initiatives, the Copper Technology Roadmap recently generated by a group of the most relevant copper mining companies, is presented, including an analysis of strategic opportunities and challenges in the Latin American region.

Sep 9, 2007

A mineral grain finder is described which is easily constructed to fit onto the stage of a standard reflected light ore microscope.The device is most useful in relocating particular grains or mineral associations on 30 mm diameter polished sections. The use of the grain finder in the teaching of ore microscopy is outlined.

Jan 1, 1988

By Brian M. Harney

The technique of remote sensing, used for many years by earth scientists, is being applied to the detection and monitoring of air pollution. Instrumentation being developed is of a very diverse nature and is effective, Fn varying degrees, at ranges from 1,000 meters to the altitude of a space satellite. This paper describes a number of the recent developments in this new field. Instruments based on spectroscopic, laser, and photographic systems are discussed. Sensors are being developed which utilize correlation spectrometry, interferometry, Raman scattering, Mie scattering, laser line absorption, and simple photographic detection.

Jan 1, 1973

By G. A. Kosick, G. S. Dobby

"This paper presents the principles and application of a recently developed control system for flotation columns and column circuits. The control system uses triple pressure sensors to directly sense zone densities and level, and to help in characterizing the operating behaviour of individual columns. A complete expert system development tool is incorporated within the system to provide the facility for full operator training, an on-line help facility, and a means for incorporating the column behavioural patterns into decision making rules. The system is configurable to any number of columns and can be run in either supervisory mode or direct control through Minnovex PIO software. Additional process signals can be interfaced with the system if desired. Operating experience with the control system on the Minnovex column flotation pilot plant is described.I: INTRODUCTIONColumn flotation cells have been more difficult to control and are more sensitive to circuit changes than conventional mechanical flotation cells. This susceptibility encouraged investigation into various types of control strategies ranging from inexpensive single pressure measurements for level control, to highly instrumented and expensive systems using a variety of control methods.Flotation operators, in many cases, do not understand the column control philosophy or have not been trained to deal with this new type of cell. Some operators have subsequently absolved themselves of the column operating responsibility. Some column cells, for example, have run for hours with slurry pouring over the top or no froth coming off at all.ColumnEX is a column flotation control system which was developed from the viewpoint of an operating shift foreman who wishes to:1. control the column or column circuit through a genuine understanding of what is happening inside the columns, and2. to share this knowledge with his flotation operators and be available to guide them through times of circuit upsets."

Jan 1, 1990

This paper reviews recent positive developments in Europe on the regulation of gold mining. However, it also examines the problem that while gold projects may be bankable and technically and environmental defensible, the odds tend to be stacked against granting of an environmental permit. The historic background to this situation is examined and current developments and initiatives are critically analysed. Standards and benchmarks for the industry have been established across the community and these have a strong influence in European Union accession (and aspiring) states as well. While this is welcome in regard to improving environmental performance, it also represents a significant milestone with mining (and particularly gold mining) now æon the mapÆ as a legitimate enterprise, a situation that was patently not the case prior to 2003. At the project level, very frequently, the difficult biophysical problems are addressed and satisfactorily dealt with according to the new regulations, but still there are problems regards trust and acceptance that underpin a æsocial licenceÆ. What goes wrong and how can companies deal with the social/environmental issues that lead to entrenched views and concerns, irrespective of any amount of demonstration of good practice and corporate social responsibility? What is the role of the non-governmental organisation (NGO) and are they as accountable and responsible as they should be? The findings presented draw upon recent experience with the environmental permitting of projects in Spain, Greece, Romania, Bulgaria and Serbia on behalf of Australian, Canadian and British companies as well as international funding institutions.

Jan 1, 2007

By Mayfield P. L J, Honeyands T. A

BHP's two million tonne per annum nominal capacity Hot Briquetted Iron (HBI) plant at Port Hedland in the Pilbara region of Western Australia is based on FINMET¦¦ direct reduction technology. The FINMET¦¦ process produces direct reduced iron (DRI) by reacting fine iron ore with reformed natural gas in a series of fluid bed reactors and then hot briquetting this DRI into dense, high quality iron briquettes. The Port Hedland HBI project represents a major investment in the chemical processing of Australian minerals to higher value products prior to export to Asian markets. This paper describes the FINMET" process and technical aspects of the high-quality HBI product, and provides an update of the current status of the project.

Jan 1, 1999

By Silver EA

The Finisterre Range on the north coast of Papua New Guinea is the uplifted forearc riagio.n. of a modern arc-continent collision. The core of the range is composed of the P- nisterre Volcanics, an Oligocene''-arc terrane. The southern flank of the range consists of a clastic sedimentary sequence which is an uplifted accretionary wedge and collision complex. This clastic sequence can be subdivided into three distinct units. To the south of aiid structurally below the Finisterre Valcanics are the Mebu beds, an Oligocene- $arly Miocene sequence of volcanolithic turbidites. The Erap Structural Complex is south of, and structurally below the Mebu 43eds. , It consists of three subunits; the 3rly Pliocene micaceous turbidites of the Sukurum unit, contemporaneous pillow basalts AF{ the Basalt unit, and Late Pliocene to Pleistocene volcanolithic turbidites of the -Nariawang unit. The Quaternary Leron Formation, a fluvial to shallow marine 'clastic unit, is the southernmdst. and structurally lowest unit of the clastic -sequence The Finisterre Range is dominated by a fold-and-thrust belt with most thrusts "dipping steeply N. Melange fabric _ is developed in the vicinity of major thrusts. "ffle thrust belt strikes NW, oblique to the regional convergence direction, but no strike-slip motion is observed along NW striking faults.

Jan 1, 1991

By Kenneth G. Skinner

The rapid growth of the metallurgical, chemical, and allied industries on the Pacific coast just prior to and during the war caused a sudden increase in the demand for refractories, which was the immediate cause of a revival in interest in refractory clays available on the Pacific coast, particularly in the Pacific Northwest. Population increases and shortage of shipping facilities caused an increase in the amount of various ceramic materials and products used and produced on the Pacific coast, with accompanying demand for information regarding sources of clay. In an effort to supply part of this information, the Bureau of Mines, in cooperation with the College of Mines, University of Washington, started a program in 1944 to test the refractory and other properties of clays from seven Pacific Northwest deposits that had been drilled and sampled as part of the Bureau of Mines alumina from clay investigation. Figure 1 shows the location of these deposits.

Jan 1, 1949

Jan 1, 1995

A preliminary program dated April 25, 1974 was prepared for Development Engineering, Inc. (D.E.I.) on research and development, laboratory; field and other engineering studies for the disposal of retorted oil shale. This program was revised and published as a final document dated December 17, 1974. The document included a discussion on the peculiarity of retorted shale materials to be investigated and a discussion of the various laboratory and field tests which would need to be conducted to define their physical and chemical properties. The proposed research and development program was divided into eight work phases as follows: I - Program Development II - Exploratory Laboratory tests on old U.S.B.M., retored shale III - Laboratory tests on Pilot Plant retorted shale IV - Laboratory tests on retorted shale from Semi-Works Plant, and field and test plots and ponds. V - Field compaction tests

Jan 1, 1975

By Xintan Chang

MFIRE is a computer simulation program that performs normal ventilation network planning calculations and dynamic transient-state simulation of ventilation networks under a variety of conditions. The program is useful for the analysis of ventilation networks under the influence of natural ventilation, fans, fires, or any combination of these. MFIRE simulates a mine's ventilation system and its response to altered ventilation parameters such as the development of new mine workings or changes in ventilation control structures, external influences (varying outside temperatures), and internal influences (fires). Extensive output enables detailed, quantitative analysis of the effects that the alteration will cause to the ventilation system. The program was developed at Michigan Technological University (MTU), Houghton, MI, with support from the Bureau of Mines. A personal computer (PC) version of the program was completed under contract for the Bureau by MTU. The purpose of this report is to document the installation and use of the PC version of the program MFIRE.

Jan 1, 1990

The Fraser Range is composed dominantly of basic pyroxene granulites derived from basalts, many of which appear to have been vesicular and pillowed. Acidic and basic garnet-bearing granulites are important in the west, and acidic granulites and narrow anorthosite layers are dominant in some regions east of the Fraser Range. An extensive flat-lying olivine gabbro sheet cuts the granulites, and in places has been converted to spineI-bearingmeta-gabbros and pyroxene granulites. The granulites of the Fraser Range (Proterozoic) are separated from the gneisses and schists of the goldfields regions (Archaean) by the Fraser Fault, over which there is a large gravity anomaly (gradient 20 milligals per mile). Some of the problems associated with the concentration of Cu, and Ni liberated from mineral lattices during metamorphism, and other principles of metal concentration in granulite terranes, are discussed. The recognition of vesicular and pillowed zones, even though highly metamorphosed, is of fundamental importance.

Jan 1, 1969

By K. Leutwyler

The key to realistic casing stress analysis in thermal recovery installations is accurate knowledge of the temperatures involved. Much information leading to prediction of heat losses from tubing string to wellbore has been published. This .same information permits calculation of casing temperature under certain conditions. This paper reviews the basis for most of the published work, the line source solution to the diflusivity equation and examines some of its application criteria in the light of unsteady-state conditions. An alternate finite differences method is presented for correlation, and experimental data pertaining to the heat transfer mechanism in the annulus is reported. In the light of the information presented in the paper, it appears that the assumption of a line source for the tubing-wellbore system is valid even for reasonably short periods of heat flow, .such as "steam soak" operations. The empirically modified equation presented earlier matches computer derived results of the finite differences approach lor periods as short as 50 hours. Previously predicted cas ing temperatures and the associated stress levels are thus verified based on these correlative computations and the reported experimental information. Fall out from the computer output resulting in some studies of the influence of insulating cement properties on casing temperature, and experimentally studied effects of nitrogen placed in the annulus at various pressures., are described. INTRODUCTION Generally speaking, predictions of average casing temperatures have been based on an idealized model involving a centralized tubing string at uniform constant temperature radiating energy towards the casing under steady-state conditions.'. ' Heat is transferred away from the casing to the formation by unsteady-state conduction across thermal barriers consisting of cement and the mud sheath. Heat balances written on the casing permit prediction of instantaneous casing temperatures. During early periods of injection, casing temperature varies appreciably as a function of time; however, for long injection times this variation decays as heat flow from the wellbore to the formation stabilizes, and it becomes virtually negligible as conditions surrounding the wellbore become quasi-steady-state (Fig. 1). Carslaw and Jaeger -escribe a solution to the diffusivity equation for a line source (Fig. 2). A constant supply of heat is introduced into the medium from the line placed into the origin of the x-y coordinate system and parallel to the z-axis. Heat spreads outward in the infinite cylindrical solid and the temperature increase on a line going through point (x, y) parallel to the z-axis at a distance r can be predicted by: The following criterion must be considered: the Carslaw and Jaeger equation is obtained on the basis of a large

Jan 1, 1967

By Dunkin H. H

Flotation tests in a laboratory flotation cell at pH 8-8.5 and other sui}plementary tests were carried out on sphalerite-quartz and sphalerite-pyrite-'quartz mixtures. Depression of sphalerite resulted vvhen the addition of copper sulphate exceeded an optimum value. Evidence that this depression was due to collector deficiency because of reaction between copper sulphate and collector is presented. It was not found possible to devise a direct analytical method suitable for .plant control of reagent addition. A possible means of control using potassium cyanide and a higher pH is discussed.INTRODUCTIONAt the Rosebery mill of Electrolytic Zinc Co. of Australasia Ltd., recovery 'of sphalerite in the zinc concentrate occasionally drops unexpectedly. Experiment in the mill and mill laboratory has suggested that one of the factors causing this may be the addition of more than an optimum amount of copper sulphate. On such occasions, an increase in the collector addition improves zinc recovery in the zinc concentrate, but only at the expense of sphalerite-pyrite selectivity.To examine the phenomenon more thoroughly, and if possible to find some means of determining the optimum addition of cepper sulphate and controlling the actual addition at this optimum, one of the authors (W. J. T.) was employed by the Electrolytic Zinc Co. of Australasia' to carry out investigations in the Mining Department, University of Melbourne, under the joint direction of R. B...

Jan 1, 1954

By W. L. Connell, O&apos

The properties of some heavy liquids which can be used in sink-float separations are discussed with major emphasis being given to the halogenated hydrocarbons. Data are presented on density, viscosity, thermal characteristics and the effects of moisture and temperature on the corrosiveness of the liquids towards various materials of construction. The toxicity of these materials, the hazards involved in handling them, and the procedures for handling them safely are also discussed. True liquids have certain advantages over colloidal suspensions for sink-float separation of minerals which makes their use especially advantageous when close separations, fine particle sizes or water-soluble minerals are to be treated. For best separating results, the medium should have an easily controlled, uniform, stable density. Here, true liquids have the advantages of allowing closer control of density and of not requiring agitation to maintain a uniform den- sity in the equipment. Low viscosities are desired in a separating liquid so that rapid separations of fine material can be made. Many liquids have lower viscosities than the colloidal suspensions at operating gravities of 1.4 to 5.0. For economic reasons and to prevent contamination of the product, the separating medium must be easily and completely removed from the ore. Normally, true liquids must be more completely removed than the cheaper suspensions and thus cause more problems in this area. The fact that the medium should not react with the minerals, air, water or the common materials of construction limits the choice of liquids which can be used, but many are available which are sufficiently stable. A more serious objection to the use of true liquids is that many of them present a toxic hazard to operating personnel and users of the product. Most true liquids are toxic to some extent, but modem knowledge of toxicity allows us to recognize the hazards inherent in handling them and enables us to design around them. Three types of true liquids are available for this use: 1) Halogenated hydrocarbons cover the gravity range from 1.2 to 3.3. They are generally more volatile and less viscous than the other liquids.

Jan 1, 1963

By J. C. Edwards

A series of four coal combustion experiments (I)' was conducted at the National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory in the Safety Research Coal Mine to evaluate the response of optical and ionization smoke and CO sensors to a small 0.61 m square smoldering coal fire which transitions to flaming combustion in the presence of diesel emissions. With the increased utilization of diesel engines in underground coal mines, it is important to be able to discriminate fire products-of-combustion (POC) from diesel emissions. One proposed method to accomplish this is the deployment and interpretation of multiple sensors.

Jan 1, 2010

By R. B. Pedersen, A. Filipa, A. Marques

"Shallow-depth (<200m) high temperature submarine hydrothermal systems are not commonly observed on mid-ocean ridge settings, as most known systems are located within arc - island-arc volcanic settings, often proximal to coastal areas (meteoric waters added). In 2013, during the Centre for Geobiology’s 2013 oceanographic cruise (R/V G.O. Sars), a dredge successfully sampled massive sulfides and hydrothermally altered rocks from the top of a volcanic edifice (~144-284 m depth) located on the northern sector of the Kolbeinsey Ridge. Dredged samples include vesicular altered basalts, and matrix supported anhydrite, barite and barite-pyrite-anhydrite volcaniclastic breccias. Sulfidesulfate breccias depict complex zoning where numerous small vent orifices are distributed with large blades of marcasite that appear intergrown with barite. Native sulfur was observed in one of these small vent orifices. On a microscopic scale, numerous spherical silica-rich structures appear associated to these breccias. These rocks are evidence for the presence of a relatively high temperature (minimum 150ºC) shallow-water seafloor hydrothermal system in the Arctic mid-ocean ridge, far from mainland influence. This new discovery presents a unique opportunity to study the dynamics of fluid chemistry, metal mobility and precipitation in shallow hydrothermal systems. The remote location of this system dictates that fluid recharge will be influenced solely by seawater and magmatic fluids, In July-August 2014 we expect to survey this new field and acquire new and comprehensive data."

Sep 1, 2014