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By J. Whitford

The established crown pillar extraction method at Gold Fields Australia Ltd.’s Crusader Mine, leads to the significant dilution and poor recovery of ore due to caving of the overlying loose rockfill. The application of selectively injecting specifically developed ‘FB200’ ettringite (calcium sulphoaluminate hydrate) type cement grout into loose rockfill to form a stabilised rockfill material, enables an artificial crown pillar to stabilise the surrounding rock mass and prevent caving of the overlying loose rockfill during crown pillar extraction. Investigation of the geomechanical criteria for crown pillar extraction beneath stabilised rockfill has enabled the safe and efficient extraction of two crown pillars at the Crusader Mine. La méthode actuelle d'extraction des piliers horizontaux à la mine Crusader dont la propriétaire est le Goldfields Australia Ltd amène à une dilution sensible du minerai, à cause de l'effondrement du remblai peu compacté qui se trouve au-dessus. Par moyen d'injection sélective du coulis de ciment FB200 ettringite (sulfoaluminate de calcium hydraté) qui a été développé spécifiquement pour cette application, un pilier artificiel est crée et celui-ci empêche l'effondrement du remblai pendant l'extraction du pilier de minerai au-dessous. A la suite des études géotechniques de la méthode, deux piliers horizontaux à la mine Crusader ont été extraites, de manière efficace et sûr. Die feststehende Krone Pfeiler Extraktionsmethode beim Crusader Mine von Gold Fields Australien GmbH, führt wegen caving des overlying lockerer rockfill zur bedeutungsvollen Verdünnung und schlechtem Wiederfinden des Erzes. Der Antrag, ausdrücklich entwickelten 'FB200' ettringite selektiv zu spritzen, (Kalzium-sulphoaluminate-Hydrat) Art kittet Mörtelschlamm in lockeren rockfill, um ein stabilisiertes rockfill-Material zu bilden, ermöglicht einem künstlichen Kronenpfeiler, die umliegende Steinmasse zu stabilisieren und caving des overlying während des Kronenpfeilerherausziehens lockeren rockfill zu verhindern. Untersuchung der geomechanical-Kriterien für Kronenpfeilerherausziehen unter stabilisiertem rockfill hat dem sicheren und tüchtigen Herausziehen von zwei Kronenpfeilern beim Crusader Mine ermöglicht.

Jan 1, 2003

By B. H. Kim

It is hypothesized that the standard approach adopted to characterize the ground and to determine the rock strength properties at depth are flawed and generally tend to underestimate the rock strength and possibly the stiffness, particularly when the rock mass is characterized as massive to moderately jointed or blocky to very blocky. It is therefore necessary to conclusively established that the hypothesis, that the rock strength in highly confined rocks is greater than generally anticipated, is actually valid and generally applicable, and then to develop new procedures to establish rock parameters that can be reliably used for the design of deep excavation.

May 1, 2009

By Michael P. Sudbury

Non-ferrous slags are granulated and stockpiled as an alternative to pit cooling or transporting molten slag to a dump. The chemical composition of such slag is determined by the pyrometallurgical process in which it is produced, while the size distribution is set by safety concerns or a desire to reduce wear of pumps, pipelines and other equipment. Relatively few operations give consideration to the effect of granulation conditions on other properties of the granulate as the material is typically accumulated on the smelter site. It is becoming recognized that slag has many potential commercial uses and carries much of the energy applied to the smelting operation. This paper outlines the findings of extensive work to identify uses for granulated non-ferrous slag, the importance of preparation conditions on the properties, impediments to more extensive use of granulated slag, the real costs of slag stockpiling and the opportunities for further productive research.

Jan 1, 2006

The first part (lH of this work dealt with the process of recrystallization of single crystals of lead after deformation by creep, as revealed by macroscopical examination. It was shown that when recrystallization commenced, a crystal, termed the primary crystal, started to grow at the edge of the specimen and extended into the body of the specimen along the slip planes. At some stage during the growth of this crystal, other crystals appeared at the boundary of this first crystal and fragments of the parent crystal. From thispoint, recrystallization was accelerated with relatively rapid necking down of the specimen until fracture occurred.All those crystals formed after the primary crystal were given the term secondary crystals. In the present paper is given a detailed account of the orientations of the primary and secondary crystals.EXPERIMENTAL METHODThe size of the test pieces and the manner of loading were given in the previous paper (1). X-ray back reflection photographs were taken of the individual primary and secondary crystals and from them were determined the orientations. The path of the X-ray beam was perpendicular to the surface of the creep specimen.In view of the large number of photographs needed, gold...

Jan 1, 1940

THE ore treated is almost pure copper pyrites (chalcopyrite) in a gangue of quartz and quartz-felsite. Very little free iron sulphide (pyrite) occurs, and at the time of the erection of the flotation plant the stopes in the oxidized zone had been almostentirely depleted. This zone only extends to a shallow depth, and, below the l00-ft. level, the sulphide for the most part is clean and bright but in the crushed and brecciated parts of the ore channel, where surface water has circulated freely, the gangue is decomposed and kaolinized, and the copper sulphide badly tarnished. This class of ore gave considerable trouble at the mill, but unfortunately, was very limited in quantity. A sample of rich ore assayed-Copper, 21.2 %; iron, 24:.3 %; silica, 28.9 %; sulphur, 25.1%.The concentration in the original mill was effected by handpicking, jigging, and tabling. A considerable portion of the copper mineral arrives at the surface in the form of large lumps of very pure quality, eminently suitable for sorting out by hand.The rich ore is tipped over a grizzly at the shaft bins; the oversize hand-picked, and the undersize bagged direct.

Jan 1, 1912

By Damon C. Gray

This report contains a recommended program of acoustic research to be conducted by the U. S. Bureau of Mines. The program is directed toward the abatement and control of machinery noise in underground coal mining operations. The study conclusions and specific problem areas which led to the definition of the recommended program are also briefly described.

Jan 1, 1971

By Grant J. Goddard

"The Iron Ore Company of Canada (IOC) has been in operation for over 30 years. Today, and in the future, technology and its application will play an ever more critical role in the company’s business success.The Carol Mining and Concentrating (CMC) division of IOC is energetically applying technology today to enhance performance and results, and is aggressively exploring opportunities to apply technology to support improved business results in the future.A critical area of focus is the application of technology to maintenance management performance. CMC has taken a “back to basics” approach to the fundamentals of maintenance management in 1995 and 1996. In parallel, the mine is aggressively implementing its Vision 2000 maintenance integration plan. This plan is targeted at levering the energies applied to sound maintenance management fundamentals as the company moves to a fully condition based maintenance approach.This paper discusses some of the strategies, key technologies and objectives of theVision 2000 maintenance integration plan at the mining operations of IOC."

Jan 1, 1996

By M Armstrong, S J. Coward, A Galli

Mine management is often expected to make rapid evaluation decisions at different stages of projects based on limited and uncertain data. The challenge is exacerbated by having to distil technical complexity into a financial model that is usually designed to produce only one or two key indicators, eg net present value (NPV), internal rate of return (IRR). Mining is a complex environment with many sources of uncertainty ranging from sampling to economics. In order to optimise investment decision-making, an appropriately structured evaluation framework must be utilised. An evaluation framework should be designed to encapsulate and integrate the complexity across the evaluation cycle, ie sampling, resource estimation, mine planning and treatment, and financial and economic modelling. This complexity is diverse and ranges from sampling support, scale effects to understanding the impact of variability, uncertainty and flexibility on operational efficiency and economic viability. These complexities, combined with time and capital constraints, usually do not allow all facets of evaluation to be integrated into the model. The model must strike a balance between simplified estimation techniques and sufficient incorporation of aspects of the project that will make a material difference to the investment decision. This paper demonstrates the impact of the scale of measurement on the valuation of a mineral project. Comparisons are made between global estimation averages using a top-down approach and local estimates using a bottom-up approach. Three sampling campaigns were conducted on a virtual orebody to compare the relative NPV accuracies. Stochastic forward models were run on foreign exchange rates and are compared with the results from a fixed foreign exchange rate model.

Jan 1, 2006

By Roy Woodall

Successful mineral exploration is the lifeblood of the mining industry. Contrary to what the environmental lobby would have the world believe, the industry is replacing the metals it is extracting. The reserve base has not changed significantly in 20 years (Fig. 1.) Mineral exploration is a research activity. First there is the idea, the vision or the intuitive thought. The experiments follow. These involve repeated phases of data gathering, data interpretation and concept testing through drilling. For many companies, exploration is the main investment in scientific research. Each mineral exploration experiment may involve years of costly work. Despite the improving tools of science and technology, the investment remains high-risk. Only the promise of high rewards, or desire to survive as a mining company, will stimulate the necessary commitment and level of investment. Confidence that an economic return can be achieved, confidence in the science and technology being applied and confidence in the people involved are the foundations upon which successful mineral exploration is built (Woodall, 1984). The challenges facing the explorationist in the 1990s fall into two categories: - the challenge to make the activity economic; and - the challenge to make the activity socially and, therefore, politically acceptable.

Jan 1, 1992

By Deno M. Pappas

This report presents results of a U.S. Bureau of Mines study of longwall gob material. The objective of this work was to determine material stiffness properties of the gob for use in numerical models of rock mass response to longwall mining, Photographs of actual mine gob were digitized to obtain approximate particle size gradations of gob material. The gradation curve was shifted down to a laboratory scale, and 20 uniaxial compression tests were conducted. Varying the maximum particle size was not found to affect the stress-strain behavior, but changing the gradation appeared to influence the stress-strain behavior. The stress-strain relationship of the simulated gob material was nonlinear, the stress-secant-modulus relationship was approximately linear, and the stress-tangent-modulus relationship was approximately a second-order polynomial function. Equations were generated from these curves, providing numerical modelers with a means to estimate gob moduli based on the stress level. In addition, the experimental data were statistically evaluated using multiple regression analyses, producing a series of equations to predict the secant and tangent moduli from the given stress level, bulking factor, rock strength, and thickness-to-width shape ratio of the particles.

Jan 1, 2010

By G. E. Perry, R. D. Seba

The steam soak process is the most widely applied and most successful thermal supplemental recovery process in use today. This process, which consists of injection of steam in various quantities into a well that is subsequently used as a producer, can be repeatedly applied to the same well. The treatment, if successful, will increase the production rate of the well for a given period. For this reason, the steam soak process should be considered primarily as an acceleration method rather than as a method for producing oil that could not be recovered by primary means. However, application of this process to reservoirs containing viscous crude may produce oil that otherwise would have zero present value or would be produced at such low rates by primary methods that it would not be profitable. A major necessity for the successful application of the steam soak process is a source of natural energy. This source of energy may exist in one or more of the following forms: expansion of fluids, compaction, gravity drainage. This study was undertaken to determine the effect of gravity drainage on steam soak production and recovery and to develop a method for predicting production rates, ultimate recovery, and heat requirements when applying this process to a reservoir in which the primary driving mechanism is gravity drainage. (For additional discussion of some of the factors that affect recovery of viscous oils by the steam soak process, see Ref. 5.) Model The model developed for analyzing the performance of the steam soak process in gravity drainage reservoirs is a modified form of that developed by Matthews and Lefkovits.1,2 The model used in this study consists of two concentric cylindrical volumes of productive formation with cap and base rock of impermeable material. The inner cylinder, extending from the radius of the wellbore to some predetermined radius, is referred to as the hot zone; and the outer cylinder extending from the exterior boundary of the hot zone to the outer drainage boundary will be referred to as the partially heated zone. Fig. 1 is a schematic cross-section of the model, indicating its thermal properties. Horizontally the reservoir is divided into two regions, the upper region having a high gas saturation and residual liquid saturation, and the lower region containing a high liquid saturation. The boundary between these two regions is referred to as the free surface, which drops and changes shape as fluid is produced from the reservoir. The model was used to analyze the steam soak process by applying the following assumptions: 1. The horizontal formation is composed of one or more homogeneous noninterconnected layers containing incompressible fluids. Each layer is treated separately. 2. The hot zone is heated by the initial soak and is maintained at the steam temperature corresponding to atmospheric pressure by resoaking. 3. The height of the free surface at the producing well is at all times zero (producing well is pumped off). 4. The position of the free surface at the start of

Jan 1, 1970

By Neil Westoll

But First, An Overview of the Selwyn Basin and Its Resources ?World-renowned sedimentary-exhalative (SEDEX) deposits of zinc, lead, silver +/-barite ?Significant reserves/resources remain and vast tracts of prospective stratigraphyremain under-explored and untested. ?More details are at the Yukon Geological Survey?s Selwyn Basin Metallogenysite:http://www.geology.gov.yk.ca/metallogeny/selwyn/ Overview of Metal Price and Demand Trends ?The pace of economic change in China has been extremely rapid since the start of economic reforms just over 25 years ago. According to official statistics, economic growth has averaged 9.5% over the past two decades and seems likely to continue at that pace for some time. National income has been doubling every eight years. Such an increase in output represents one of the most sustained and rapid economic transformations seen in the world economy in the past 50 years.? Organization for Economic Co-operation and Development 16-Dec-2005

May 1, 2006

By B. Erdem

This article introduces a computer model, which emphasizes panel design for draglines deployed in direct side-casting mode. The study covers flat and inclined coal-seam conditions with the dragline operating along the strike-line. Two casting methods are embedded in the model: material is placed in the open set adjacent to the one on which the dragline is located (the DNS method) and material is placed in the open set adjacent to the one the dragline excavates (the DND method). While in the first method the unproductive walking time is reduced as the set is enlarged, in the second method the cycle time is lessened as the dragline swings along an acute angle. The side-casting model is shaped so as to provide several panel configurations instead of a single one to conform to the characteristics for an opencast mine. This is achieved by assigning the pit width an interval of values ranging from a minimum to a maximum. The model includes solutions to other critical design parameters such as: set length, swing angles at key cut and main cut positions, and required dragline reach at key cut and main cut positions. The model outcomes reveal the following: the stripping operation is largely affected when the coal-seam is inclined. The downhill spoiling mode should be applied wherever possible. The DNS pattern allows wider pit width intervals as well as longer sets and longer reaches.

Jan 1, 2004

By Gordon B. French, Donald E. Garrett

INTRODUCTION Crude oil reserves in the United States are still very large, even though for many years they have not been sufficient to supply our entire domestic requirements. They are continuously being depleted as oil is pumped from the ground, but new discoveries and improved secondary and tertiary recovery methods are helping to reduce the rate of depletion. It is thus a slowly diminishing resource, but even as it is being consumed, immense reserves of oil are left behind as the so called "un-recoverable" portion of petroleum formations. Most oil fields can only obtain a 15 to 40% recovery of the original reservoir, and it is widely quoted that there are still about 300 billion barrels of this un-recoverable oil still in place (Mauch, 1980, etc.). With the present comparatively high oil prices, and the possibility of even higher future prices and short supply, this oil becomes an interesting potential reserve. Mining the petroleum formation would be one means of recovering at least a portion of this oil. The concept of oil mining is neither new nor limited to conventional oil fields, since the procedure could be equally employed with the otherwise difficult to produce heavy oil deposits, and the solid or semi-solid tar sands and diatomaceous hydrocarbon formations. Estimates place the U.S. tar sand resource at about 30 billion barrels, and heavy oil at 5-10 billion barrels (Unitar, 1982). Figure 1 graphically summarizes the heavy oil reserves based upon formation depth and characteristics, while Figure 2 shows their location. It is apparent that the preponderance of reserves are in California and Texas, but that they also occur in many other states. The major companies engaged in oil recovery from the heavy

Jan 1, 1983

By Silvano Morelli, Giovanna Cassani, Renzo Bindi, Antonio Nicola

More than 70 km of main line and service tunnels have been excavated to date for crossing the Apennines between Bologna and Florence. A new design and construction approach, known as Analysis of the Controlled Deformation in Rock and Soils, (ADECO-RS), was adopted to tackle the extreme heterogeneity of the ground and the particular stress-strain conditions. The goal of this system is to obtain constant and predictable full section advance rates, even in very poor geology, with the highest possible level of safety and reliability. The execution of this gigantic project required the mobilization of 21 job-sites, with the concurrent operation of 30 excavation headings. The global production rates confirm the high quality of the design and the high level of industrialization reached during the construction stage, levels not previously obtained in similar conditions, using other approaches such as NATM.

Jan 1, 2003

The Cowarra gold mine is at latitude 36°O'S. and longitude 149°19'E. which is roughly 20 miles north-north-east of Cooma.The deposit was· originally worked towards the end of the last century, but the presence of sulphides associated with the gold in the primary zone caused cessation of work when that zone was reached.GEOLOGY AND MINERALIZATIONThe principal country rocks are sandstones and shales of Silurian and Ordovician age, both very strongly folded with structural pitches ranging from a few degrees to almost vertical. The mine proper is within Silurian rocks and the main orebody (there are several minor parallel bodies) is developed within a shear striking approximately north, dipping approximately 70° east, and ranging in width from 2 ft to 15 ft but averaging about 4 ft.This shear is impregnated with quartz and sulphides with which the gold is associated. The predominant sulphide is pyrite though pyrrhotite is commonly present in quantity.Arsenopyrite and bornite are present in smaller amounts.Stillwell (1936, 1937a, 1937b, 1938, 1941) has published five mineragraphic reports on the ore.The various levels have been mapped in detail (Figs. 1-3) and the No. 2 level plan (Fig. 1) shows the general relationship of shearing, as now indicated by mineralization, and faulting. There is no apparent connection between the fold structures and mineralization.Fig. 3 is a longitudinal projection showing the distribution of gold expressed as inch-ounces. The estimation of...

Jan 1, 1965

By Nikhil Dhawan, Veeranjaneyulu Rayapudi

This study investigates upgrading of low-grade banded hematite quartzite iron ore (Fe ~31%). Conventional beneficiation was found to be futile. The susceptibility of iron phases to microwave exposure and their selective absorption assists in the liberation of iron values. Microwave exposure of coarse particles at 540 W for 10 min yielded a concentrate with Fe 56.30% and recovery of 50.68%. Conventional carbothermic reduction at 500 °C, 60 min and 9% charcoal yielded a concentrate with Fe 57.6% and iron recovery of 68%. The presence of sufficiently bonded silica leads to an easy formation of a fayalite phase. The microwave reduction design yielded FeG of 57.6%, FeR of 47% and a yield of 24% at an optimal condition of 540 W, 8 min and 6% charcoal. It was found that a small fraction of microwave-irradiated ore-charcoal mixture melted rapidly, and pure ferrite balls were observed within 8 min. An optical micrograph of a ferrite ball reveals the retained austenite and martensite phase.

By S. L. R. Lenharo, H. Kahn, H. Born

Different ore types result from the irregular spatial distribution of the associated alkaline/carbonatite rocks and the zoned alteration profile within which apatite may have undergone reprecipitation. Different flotation responses are caused by their mineralogy, iron oxide impregnation and grain-size characteristics. Samples from seven deposits were crushed, screened and separated before being studied by chemical analysis, optical microscopy, X-ray diffraction, FTIR spectroscopy, cathodoluminescence and scanning electron microscopy. Two main apatite varieties with peculiar crystal morphology were identified: hydroxy-fluorapatite as the primary phase and carbonate-fluorapatite as the reprecipitated phase. The former occurs as prismatic or ovoid grains and the latter as polycrystalline aggregates or crusts on the primary grains; both are associated with iron oxide coatings (primary) or intergrowths (secondary). Microflotation tests showed variations in flotability for particular apatite associations as well as intensity of iron oxide coatings. The differences in flotation behaviour can be related to morphological properties and chemical substitution in the apatite structure

Aug 1, 1996

By McHenry Mosier

The Bureau of Mines, United States Department of the Interior, has established a testing adit on the Government reservation at Mount Weather, Virginia, to facility to research on the fundamental tats of mining under actual metal-mining conditions. A number of sites in several Eastern States were investigated, out Mount Weather was selected because the rock seemed best suited for rock drilling and other mining tests and because the ground was already owned by the Federal Government, the site having been acquired in 1902 for use of the Weather Bureau. The testing edit has an advantage over en active metal mine for certain investigations because variable conditions affecting any particular research problem can be controlled and maintained in a fixed status, whereas in an operating mine this seldom is feasible. Operations were begin September 1935, with a crew of four laborers under a resident engineer. The laborers were recruited from, nearby farms, and. although they had no previous mining experience, they have developed into satisfactory miners.

Jan 1, 1939

Editor’s note: As usual, the June issue features an industrial minerals review. And some thanks are in order. Thank you to the industrial minerals annual-review editor, to the technical committees chair and vice chairs and to the authors of the individual commodity profiles. Jim Norman of GeoTrans Inc. is the industrial minerals annual-review editor. Lucy McCartan, US Geological Survey, was the chair of the SME industrial minerals technical committees. She also served as the vice chair for agricultural minerals. Other technical committee vice chairs were: •Gary Tomaino, Specialty Minerals Inc., ceramics and refractory materials. •Srinivas (Vas) Veeramasuneni, US Gypsum, chemical raw materials. •William Langer, US Geological Survey, construction materials. •Vanessa Santos, Independent, fillers and pigments. •Richard Berg, Montana College of Mineral Science and Technology, specialty minerals. Their help makes possible this June industrial minerals issue. On behalf of the readers, the editors thank them.

Jan 1, 2002