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By John H. Fowler

"Most of the aggregate used in Nova Scotia is produced from numerous glaciofluvial and ice-contact deposits scattered throughout the province. Production from bedrock sources is increasing, with most of the coarse aggregate used in the Halifax-Dartmouth area coming from quarries operating within the metro area.A recently completed provincial sand and gravel inventory mapping program has identified some ""resource-poor"" areas where comprehensive aggregate evaluation programs are underway. Although some areas of the province are experiencing aggregate supply problems, large volumes are exported to markets as far away as Bermuda.IntroductionThe Nova Scotia Department of Mines and Energy has been involved with aggregate resource studies for several years, although sand, gravel and crushed stone are not designated as minerals under the Mineral Resources Act of Nova Scotia. Our role has been to provide the aggregate industry with resource data as well as provide similar information to governmental agencies involved with municipal planning, water resource studies and environmental protection regulations. Several private consulting firms use the information in many of their site development studies.We became involved with aggregates in a rather roundabout way. Several years ago, an outcry from inhabitants of a small coastal community over the removal of sand and gravel from a local beach moved the provincial Department of Lands and Forests to take action to protect provincial beaches. We were asked by the Department to provide information and to suggest alternative sources here operators extracting sand and gravel from beaches could relocate. This request initiated an aggregate inventory survey in southeastern Cape Breton, which was later extended to cover the entire province. The initial provincial sand z and gravel inventory survey provided a series of 1:50,000 maps showing the distribution of sand and gravel deposits in the province."

Jan 1, 1982

By T. Baker

The Eloise Cu-Au deposit is 60 km SE of Cloncurry in NW Queensland and has a current indicated reserve of 3.2 Mt @ 5.8 per cent Cu, 1.5gA Au and I9g/t Ag. It is hosted by metasediments and metabasic rocks that underwent amphibolite facies metamorphism at 550-600¦C and less than 3.5 kb. Peak metamorphism coincided with the regional D2 event which produced an S2 foliation with north-south strike and variable sub-vertical to steep east or west dip. The deposit is associated with several major shear zones parallel to the S2 foliation. The lodes form part of a large alteration system that is localised by the retrograde shear zones. Homblende-biotite-quartz with minor sulphides occur early in the alteration paragenesis which is overprinted by chlorite-muscovite-pyrrhotite-chalcopyrite ¦calcite+¦nagnetite. The later assemblage replaces the earlier Fe-K alteration as well as Fe-rich metamorphic assemblages such as homblende, biotite and staurolite indicating a post peak metamorphism timing for ore formation. Although replacive textures are the most common, the alteration can display open space infill and brecciation as well as durchbewegung and mylonite textures indicating that mineralisation occurred during ongoing ductile deformation. All these features are crosscut by a later brittle phase of calcite-chlorite-quartz¦pyrite alteration.

Jan 1, 1994

By L Mollison, K W. Mills, N R. P Baczynski, M F. Lee, I A. de Bruyn

This is the first of two papers concerned with rock stress inputs to various mine design issues at the large Ok Tedi open pit mine in Papua New Guinea. The companion paper (also published at this conference) is ‘The Application of Rock Stress Inputs to Stability Assessments at Ok Tedi Mine, Papua New Guinea’ (de Bruyn et al, 2014).Stresses are a required input for numerical modelling of mine design issues. However, for some operations, like the very large Ok Tedi open pit mine in remote rugged mountainous terrain, direct and representative measurement of rock stresses can be technically difficult and expensive. In such situations, development of an appropriate and sufficient understanding of rock stresses can be challenging.This was addressed for Ok Tedi by considering the following:The tectonic and regional geologic setting of the mine.Results from three different programs of rock stress measurement over 19 years, including hydraulic fracturing (1991), acoustic emission (2007) and overcoring (2010). Some interesting results of the overcoring work are discussed. It was done in a 4 km long drainage tunnel, which intersected a thick monzodiorite intrusive that has metamorphosed contacts to host contact Ieru Formation siltstones; anomalously low horizontal stresses were measured within the monzodiorite.Compilation of rock stress measurements from other New Guinea mines and prospects, both in Papua New Guinea and Indonesian West Papua.Comparisons between the variable Ok Tedi rock stresses and similar data from other porphyry copper deposits.CITATION:Lee, M F, Baczynski, N R P, Mills, K W, de Bruyn, I A and Mollison, L, 2014. Rock stresses at Ok Tedi, Papua New Guinea, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 337–346 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

A localized nonlinear recoverable resource estimate technique has been applied using typical feasibility or new mining drilling data configurations drawn from a massive database from a mined-out area on a hydrothermal gold deposit. The results were then compared with the corresponding 8 m x 5 m grid grade-control data in order to determine the efficiency of the approach and the validity of the recoverable resource estimates for mine planning and financial forecasts.

Jan 1, 2014

By Hämäläinen M., O. Hyvärinen, E. Jääskeläinen

HydroCopperTM is a new hydrometallurgical process for the treatment of copper sulphide concentrates, which has been developed by Outokumpu. The process includes chloride leaching of copper concentrate, solution purification and precipitation of copper(I) oxide, an intermediate product, which is reduced and cast into copper products. The reduction can be carried out by pyrometallurgical methods or hydrometallurgically in an autoclave. This paper discusses the thermodynamic and kinetic aspects of the hydrogen reduction of copper(I) oxide in an autoclave. The results of the laboratory tests are presented and discussed. Finally, the autoclave method is compared with other options.

Jan 1, 2004

By John A. Ferguson

John Ferguson of Phelps Dodge provides us with a case study of how his company approaches its computing and hardware decisions. Senior management is the target audience for this contribution which discusses computer employment strategy at Phelps Dodge and how it may differ from the practices followed by other companies. The computer professional is well advised to read this subsection also to gain insight into the way in which management looks at computers in support of company operations. The following pages take us through a progression of developments and expectations brought about by the computer: the tremendous versatility of this new tool and its swift development; the widespread changes and problems it introduced; the new and revolutionary management theories it prompted and the widely supported centralized service concept it introduced to information processing. It continues with a discussion of Phelps Dodge's early experience, its ,operating environment, and its strategy development-attention to operating units and later headquarters with stress on service needs of users. It concludes that for computing to be effective it must fit in with the bay in which the company operates and must be sensitive to the needs of the people it serves.

Jan 1, 1979

By Howard I. Smith

THE mineral trona was discovered on Government land in 1938, about 18 miles west of the town of Green River, Wyo., in the core of the John Hay, Jr., well, a test well drilled for oil by the Mountain Fuel Supply Co. in sec. 2, T. 18 N., R. 110 W., sixth principal meridian. Although no oil or gas was reported, the drilling led to a discovery of great potential economic importance and exceptional scientific interest. Trona is a relatively rare mineral found at various places in playa deposits but not previously found at any great depth. It is composed of hydrous sodium carbonate and sodium bicarbonate (Na2CO3.NaHCO3.2H20). Pure trona contains the equivalent of 70.35 per cent of sodium carbonate. Total sodium computed to carbonate times 1.42 equals the percentage of trona in the absence of other sodium carbonate minerals in the sample. ANALYSES Two short pieces of core sent to the author a few days after the completion of the Hay well were analyzed by R. C. Wells[t] and found to be exceptionally pure trona. A brief article on this discovery has already been published.1 Arrangements were then made through W. T. Nightengale[$] for the author to inspect and sample the core. The company log of the well included notations of sodium salt crystals from a depth of 1190 to 1820 ft. Not being able to identify all the minerals present, the author selected several specimens of the core for petrographic examinations and sampled the sections of trona for analysis. J. J. Fahey, of the Geological Survey, examined the specimens and reported most of the crystals to be a new anhydrous sodium carbonate and calcium carbonate mineral (Na2CO3.2CaCO3), which he named shortite,2 after Maxwell N. Short.* He analyzed the samples of trona, with the results shown in Table I. [ ] In addition to the 10 ft. I in. of trona in the first section, it is reasonable to assume that the 9 ft. 8 in. for which no core was available for sampling is either mostly trona or some other soluble salt, but it should not be included in calculating reserves. In the part of the core between 1590 ft. 3 in. and I600 ft. 4 in. the material insoluble in cold water, amounting to about 5 per cent, was estimated petrographically to contain 70 per cent clay, 25 per cent shortite, and 5 per cent pyrite. ACCOMPANYING MINERALS Fahey later secured about 600 ft. of the core for a detailed examination and study

Jan 1, 1942

By M. P. Adamson, Bryson D. Trexler, R. V. Ramani, Mark L. Koenig, V. Rajaram, Alan Burton, C. S. Crocker, Kim. Y. C., A. G. Law, William C. Larson

Another record year vas experienced by the mining industry as the value of nonfuel minerals production soared to $23.5 billion-up 15% from the previous year. Based on preliminary estimates by the Bureau of Mines, US mine output was the basis for about $225 billion worth of minerals-derived materials. Metal mining accounted for $8.5 billion, or 36%, of the total. Of the 22 metals produced in the US, 11 showed quantity increases, while 16 had value increases. Business Week's survey of 1200 companies (Mar. 17, 1980, pg. 81) revealed that 21 metals and mining companies had sales increases of 30% with earnings up 104%. Higher prices and increased demand for metals were primary factors behind the improved performance. The steel sector reported a 30% decrease in earnings for the year, but the slump was primarily the result of a $383-million loss for US Steel coupled with a 17% decrease in earnings at Inland Steel. Other firms did well in 1979, with earnings up 279% at Interlake and 269% at Kaiser Steel. Major obstacles facing the steel industry included substantial tonnages of dumped and subsidized imports, environmental expenditures, runaway inflation, and price controls. Turning to nonmetallic production, of the 49 commodities reported by the US Bureau of Mines, 29 had higher outputs and 39 had increased values. While production statistics may seem encouraging, government regulations continued to stifle industry efforts to develop needed new capacity. A case in point may be publication of the Environmental Protection Agency's simplified procedure to streamline five permit programs by consolidating them into one. The five included: hazardous waste management, national pollution discharge elimination, dredge and fill, underground injection control, and prevention of significant deterioration. The new procedure, published by EPA in the Federal Register, took 149 pages. AMC's J.A. Overton, Jr., noted that (MCJ, Nov. 1979, p. 39) to visually depict the complexity of the proposed regulations, Sell Oil Co. developed a flow chart mapping a path through one section. The chart required 10 days to map and two weeks for two draftsmen, using computerized drafting techniques, to plot the results. Overton said, "Perhaps the greatest service EPA has performed in preparing its proposal is to demonstrate again that federal regulations have become a complexity compounded by confu¬sion that culminates in a conundrum." While regulatory agencies promulgate new regulations, the lack of a cohesive government minerals policy remained a matter of significant importance to mine management. A non-fuel minerals study to provide input to the Administration for a national minerals policy program was a dismal shock, according to Rep. Jim D. Santini (D-NV). He said the first phase of the program, which was to identify industry problems, failed to come to grips with the hard decisions necessary regarding these problems, their impact, and their interrelationship. Santini said the report failed to acknowledge government's role in the process and absolved the government of any adverse influence on the domestic minerals industry. In response to the phase one report, eight senior mining executives testified before Santini's House Subcommittee on Mines and Mining concerning mineral supply, access to foreign sources, environmental protection, conservation and recycling, national security, and capital formation. By year's end, Rep. Santini promised to prepare a hard-hitting committee report on problems affecting the non-fuel minerals industry to provide a better base for subsequent policy recommendations (MCJ, Jan. 1980, p. 34). On the technological front, interest again centered on mechanization, automation, and scaleup to improve and expand production. Computer use increased for calculation of ore reserves, mine planning, operations research, and mineral processing.

Jan 5, 1980

By J. M. Schisler

In the last five years Eldorado Resources Ltd. (ERL) has undergone a major expansion and modernization of its uranium refining and conversion plants. A new refinery for processing yellow cake to UO3 was constructed at Blind River in northern Ontario and started up in 1985. Its rated capacity is 18,000 t/a uranium as UO3. At Port Hope, Ontario, ERL's new UF6 conversion plant has been constructed. This plant started up in 1984. It utilizes the novel, wet-way process to produce UF4 and gives the company a UF6 production capacity of 14,500 t/a U. Also at Port Hope is Eldorado's ceramic UO2 powder production facility, commissioned in late 1980. It has a capacity of 1700 t/a uranium as UO8. With the completion of these capital projects, Eldorado has the largest and most up-to-date refining and conversion facilities in the western world. This paper reviews the refining process and process design. The methodology used to start up the Blind River plant is described as are some startup difficulties, solutions that were developed, and the resultant current operation.

Jan 1, 1987

By G. R. Brophy, A. J. Miller

The Grossmann principle1 for the calculation of hardenability of steel from composition is attractive because of its simplicity. It postulates that the hardenability of a steel for any particular grain size may be expressed in terms of an ideal critical diameter, which is the product of an ideal critical diameter for a "pure" iron-carbon base multiplied by a succession of factors for each element of composition contained, including the incidentals. It infers that the multiplying factor for a given quantity of an element is constant for all combinations of composition. Gross-mann has stated that in the great majority of cases the experimental values of hardenability are found to be well within 10 per cent of the calculated values. The validity of the scheme has been confirmed in principle by Crafts and Lamont2,3 and by Kramer et al.4 Their results differ from the original in the magnitude of the effect of some elements but, since they accepted the product concept and followed its direction, it is to be ex~ected that similar results would be obtained. Crafts and Lamont, in their second Paper, recognized that the factor relations for manganese and nickel were not continuously linear, but beyond certain critical amounts increase sharply. Austin, Van Note and Prater6 demonstrated nonlinear relations between hardenability and alloy contents. Their curves for chromium, silicon, manganese and nickel were all convex upward to show decreasing incremental effects. They concluded that Grossmann's factors under-evaluate the hardening effect of low percentage additions of these elements, and overevaluate the larger additions. More recently W. Stevens has found that the factor method fails when applied to complex steels containing two or three principal alloying elements other than carbon. Multiplying factors derived from his results bear a complex relation to composition and are not constant for a given amount of an element as the base composition varies. C. A. Liedholm7 found that, using either the Grossmann or the Crafts-Lamont multiplying factor values, not only were the relative hardenabilities of two heats of S.A.E. 6130 chromium-vanadium steel

Jan 1, 1947

By A. J. Miller, G. R. Brophy

The Grossmann principle1 for the calculation of hardenability of steel from composition is attractive because of its simplicity. It postulates that the hardenability of a steel for any particular grain size may be expressed in terms of an ideal critical diameter, which is the product of an ideal critical diameter for a "pure" iron-carbon base multiplied by a succession of factors for each element of composition contained, including the incidentals. It infers that the multiplying factor for a given quantity of an element is constant for all combinations of composition. Gross-mann has stated that in the great majority of cases the experimental values of hardenability are found to be well within 10 per cent of the calculated values. The validity of the scheme has been confirmed in principle by Crafts and Lamont2,3 and by Kramer et al.4 Their results differ from the original in the magnitude of the effect of some elements but, since they accepted the product concept and followed its direction, it is to be ex~ected that similar results would be obtained. Crafts and Lamont, in their second Paper, recognized that the factor relations for manganese and nickel were not continuously linear, but beyond certain critical amounts increase sharply. Austin, Van Note and Prater6 demonstrated nonlinear relations between hardenability and alloy contents. Their curves for chromium, silicon, manganese and nickel were all convex upward to show decreasing incremental effects. They concluded that Grossmann's factors under-evaluate the hardening effect of low percentage additions of these elements, and overevaluate the larger additions. More recently W. Stevens has found that the factor method fails when applied to complex steels containing two or three principal alloying elements other than carbon. Multiplying factors derived from his results bear a complex relation to composition and are not constant for a given amount of an element as the base composition varies. C. A. Liedholm7 found that, using either the Grossmann or the Crafts-Lamont multiplying factor values, not only were the relative hardenabilities of two heats of S.A.E. 6130 chromium-vanadium steel

Jan 1, 1947

By Kéiko H. Hattori, Neil T. Pettigrew

"Abstract- The Legris Lake Complex is a northeast-trending, 7.3 km long by 3.5 km wide, maficultramafic intrusive complex located in the western Wabigoon Subprovince of the Archean Superior Province. It is one of a series of mafic-ultramafic igneous complexes, the most notable of which is the Lac des Iles Complex, host to Canada’s only producing Pd mine with reserves of 93.5 Mt grading 1.53 g/t Pd as of December 2001 (North American Palladium Ltd., Annual Report 2001). Cu-Ni- PGE mineralization was first discovered in the Legris Lake Complex by a local prospector late in 1999. Shortly thereafter, the property was jointly optioned by Avalon Ventures Ltd. and Starcore Resources Ltd., who continue to discover significant Cu-Ni-PGE mineralization.One of the most notable features of the Legris Lake Complex is the occurrence of extensive brecciation caused by multiple injections of volatile-rich magma. The Cu-Ni-PGE mineralization is hosted by leucogabbro within a 2 km long by 600 m wide, highly brecciated area in the northwestern area of the Complex. The mineralized rocks contain disseminated to blebby sulfides (1 to 5 vol.%), comprising chalcopyrite + pyrite ± pyrrhotite + millerite ± pentlandite, typically surrounded by epidote. The majority of the Cu-Ni-PGE mineralization displays low ratios of Pt/Pd (~0.20) and high ratios of Cu/Ni (~2.9), which are similar to those of the Lac des Iles and the River Valley mafic-ultramafic complexes. The lithologies in Legris Lake Complex bear similarities to the heterolithic gabbro of the Twilight and Roby Zone deposits at the nearby Lac des Iles mine. However, the mineralization at Legris Lake, which is restricted to leucogabbro overlying unmineralized clinopyroxenite, is similar to that of stratiform deposits such as the Stillwater and Munni Munni complexes. The mineralization at Legris Lake is best explained by the late-stage, immiscible separation of a sulfide melt from volatile-rich parental magmas and the subsequent minor redistribution of metals by deuteric fluids."

Jan 1, 2001

By J. Guzman

Introduction The Carlin Trend is North America's premier gold producing district. It is located in northeastern Nevada's Elko and Eureka Counties along a northwest trending belt about 65 km (40 miles) long and 8 km (5 miles) wide (Thorstad, 1989; Jones, 1989). This trend is the worldwide reference site for epithermal, sedimentary rock-hosted microscopic gold deposits. At least 19 deposits have been discovered to date, varying in size from 933 kg to 1.08 kt (30,000 to 35 million contained oz) of gold (Fig. 1). Newmont Gold Co. and its parent, Newmont Mining Corp., jointly constitute the largest mineral right holders in the district. They own or control more than 1000 km' (386 sq miles) in and around the Carlin Trend and own all or part of I6out of the 19 mines and prospects identified to date. Since the initiation of Newmont's exploration activities in the Carlin Trend in 1961, 2.24 kt (72 million oz) of cumulative gold resources have been identified. Cumulative production from all mines since the start-up of Newmont's Carlin mine in 1965 to the end of 1989 was about 202 t (6.5 million oz) (Jones, 1989). The incentive of sustained high gold prices and innovation in processing technology resulted in a significant acceleration of gold output over the last few years. Newmont Gold alone produced more than 43.5 t (1.4 million oz) in 1989. That is equal to 22% of the cumulative 1965 to 1988 output, and an almost 200% increase over its 1986 output. The same incentives produced even more spectacular exploration results. In each of the last five years, net additions to reserves and resources outpaced current production by substantial margins. These facts demonstrate the spectacular past prospectiveness of the Carlin Trend and the success of focused, multi-disciplinary exploration methods that made it possible to more than offset the recent accelerated depletion of gold resources. However, is this situation sustainable? How long can the mining companies along the Carlin Trend keep on finding resources faster than they deplete them? These are some of the questions that motivated this study. The authors have not quantified the future potential for gold exploration in the Carlin Trend nor established a deposit discovery path. But strong indications were discovered that the [ ] Carlin Trend remains a relatively immature exploration district and that the potential for significant new discoveries is high. Methodology and data The approach chosen to address the above questions was simple. The authors compiled deposit size data, measured in contained ounces of gold resources, for all known deposits along the Carlin Trend (Table 1). The resource information was obtained by adding cumulative historical production (adjusted for mining losses and metallurgical recovery) to 1989 year-end published resource inventories. In a mature exploration area, where most deposits have been discovered, this distribution would be expected to approximate lognormality and would plot along a straight line on a lognormal probability scale. This result was found in previous work by Allais (1957) and recently confirmed by Cox and Singer (USGS, 1986) in regard to various types of mineral deposits in several regions of the world. It was also found to hold true for oil and gas pool size distributions (Arps and Roberts, 1958; Kaufman, 1962; McCrossan, 1969). [ ] The data used were compiled by Newmont Exploration geologists. The purpose of the study is to make inferences about the underlying geologic processes in the district and the maturity of the exploration effort. Therefore, deposits were not classified according to ownership but according to geologic occurrence as known from current information. Newmont's Post and Barrick's Goldstrike and Betze deposits, for example, are shown as a single occurrence to reflect the actual geologic setting. The cumulative frequency distribution of deposit sizes was plotted on lognormal probability paper (Fig. 2). The abscissa shows the cumulative fraction of deposits at or below a certain deposit size and the ordinate shows the deposit size in thousands of ounces of contained gold resources.

Jan 1, 1992

In-pit crushing and conveying (IPCC) is being increasingly considered as an alternative to traditional truck-shovel mining methods. The move towards IPCC is driven by a number of factors including the potential to reduce greenhouse gas emissions, the availability of skilled labour and the need to increase extraction rates to levels that present significant challenges to traditional methods.When considering the relative performance of IPCC and truck-shovel methods, the outcome can be inadvertently impacted by either the use of different simulation approaches, or techniques that do not adequately model the processes in sufficient detail.A simulation approach is proposed that models both IPCC and truck-shovel using the same software platform and is capable of functioning at a wide range of resolutions from life-of-mine scale through to second-by-second asset tracking level. The simulation framework also holds models of processing equipment and hence the mining simulations can be extended to gauge the impact on downstream plant.The approach, known as mine-process operational simulation (MPOS), can be tailored to the level of information available and hence the type of study required, ie order of magnitude, prefeasibility, feasibility, or detailed design.Using information from block models and a range of detailed equipment and process models, MPOS can span major system discontinuities, typified by the mine-plant interface, to allow the estimation of final mine and plant product specifications.

Dec 6, 2010

By C. Erichsen, J. Werfling

ABSTRACT: A three-dimensional elastic constitutive model for rock salt is proposed. This stress strain law takes into account the three phases of creep (transient, steady state and accelerated creep), dilatancy, as well as the failure and post failure behaviour. The model was implemented into a finite element program and validated on the results of laboratory tests and in situ measurements. A good qualitative and quantitative agreement with the test and measurement results is achieved. A stability analysis for an underground repository in rock salt is presented. ZUSAMMENFASSUNG: Es wird ein dreidimensionales elastisch-viskoplastisches Stoffgesetz für Steinsalz vorgestellt. Mit diesem Stoffgesetz können die drei Kriechphasen (primäres, sekundäres und tertiäres Kriechen), Dilatanz sowie das Bruch- und Nachbruchverhalten erfaßt werden. Dieses Modell wurde in ein Rechenprogramm, das auf der Methode der finiten Elemente basiert, implementiert und an Ergebnissen von Laborversuchen und in-situ-Messungen validiert. Die Versuchs- und Meßergebnisse lassen sich mit diesem Stoffgesetz qualitativ und quantitativ gut nachvollziehen. Als Anwendungsbeispiel wird der Standsicherheitsnachweis für eine Untertagedeponie im Steinsalz erläutert. RÉSUMÉ: Cet article présente un modéle constitutive élastique/viscoplastique à trois dimensions pour sel gemme. Ce modéle comprend les trois stade de fluage (fluage primaire, secondaire et tertiaire), la dilatation, le comportement de défaillance et d'après défaillance. Il est implanté dans un programme de calcul aux éléments finis. À l'aide des essais laboratoire et des mésures in situ, le modéle a été validé. Les résultats des essais et des mesures concordent qualitatifs et quantitatifs aux résultats des calculations.

Jan 1, 2003

By J. Crummy, I. K. Anderson, A. J. Hall, R. S. Haszeldine

Bedrock gold mineralisation has been located in association with an extensive float train 25 km west of known alluvial gold. It is in the form of open, matrix-supported breccias comprising pyritic quartz/sericite clasts in a vuggy, cherty chalcedonic and crystalline quartz matrix. Fluid inclusions in pyritic clasts indicate trapping temperatures for gold mineralising hydrothermal fluid of 170-240 degrees C. This mineralisation could represent the upper part of a feeder zone to an exhalative hydrothermal system. It is possible that other high-level feeder zones could be preserved elsewhere in the area. Deep weathering of such a system could provide a source for the alluvial gold localities near Helmsdale. It is suggested that east and central Sutherland presents good prospects for exhalative epithermal gold mineralisation and the associated feeder zones

Jun 19, 1905

By H Bleuler

A new portal and access drift was constructed by Concrete Constructions for BHPÆs Elouera Colliery, south of Wollongong.The portal area at the base of the Illawarra Escarpment is in soft colluvium material, underlain by highly to moderately weathered sandstone. The area has a well documented history of slope movement or slope creep and one of the main criteria for the design was to minimise disturbance to the unstable slope by limiting the excavation for the portal establishment. This was achieved by incorporating a sloped headwall and gabion wingwalls to accommodate the anticipated creep and groundwater seepage.Main features of the design process also included the provision of both primary and secondary support in a single shell application and the use of canopy tubes to provide support ahead of the tunnel face.The active involvement of the designer during the construction phase and the flexibility of the design concept allowed changes to the support methodology to be carried out as excavation proceeded.This paper describes the design process undertaken for portal establishment and access drift to cater for the variability of the exposed ground conditions along the drift alignment.

Jan 1, 1999

By Snehanshu Pal

"Concrete understanding of fluid dynamics properties inside basic oxygen furnace (LD converter) and hot-metal surface deformation due to impinging oxygen jet is important for optimization of reaction kinetics and maximization of productivity and refractory lining life. In this study various k-å turbulence models and volume of fluid (VOF) method have been used to model fluid flow and interaction of impinging oxygen jet with hot metal for an industrial scale top blown LD converter.RNG, standard and realizable k-å turbulence models are used to study velocity magnitude, stream function, turbulence intensity profiles. Turbulence kinetic energy, turbulence eddy dissipation, velocity magnitude and probable mixing time have been calculated in three locations inside the converter.The average rate of oxygen jet penetration, location of vortex formation, centre line and superficial velocity of impinging oxygen jet, probability of emulsifícation are studied by VOF method.These simulation studies provide better understanding of phenomena inside LD converterIntroductionComputational fluid dynamics (CFD) modeling in the field of basic oxygen steelmaking can improve substantially the understanding of existing processes where investigation of liquid steel flow measurement is hardly possible due to the rough ambient circumstances. In order to reasonably predict gas stirring operations and emulsifícation, mass, momentum, energy transfer and dynamic interaction among ions, atoms, molecules in the bath, detailed information on flow patterns, fluid velocities, and turbulent properties is essential. Concrete understanding of bath fluid dynamics inside basic oxygen furnace is also important for optimization of reaction kinetics inside the bath and maximization of LD converter lining life."

Jan 1, 2012

By Edward A. Metz, R. Larry Grayson, Douglas F. Scott

We describe inconsistencies in disease and illness reporting in U.S. mining, identify under-reporting of disease and illness in U.S. mining, and summarize selected disease and illness in U.S. mining from 1983 through 2001. Methods: We summarized information on mining-related disease and illness data for the years 1983-2001 from the Mining Safety and Health Administration database (MSHA). Results: Discrepancies exist in types of information collected by the Centers for Disease and Control, the National Institute for Occupational Safety and Health, and the Mining Safety and Health Admin¬istration database. Several factors, including a worker's fear of losing his or her job, health insurance, or other job-related benefits contribute to under-reporting of disease and illness information in the US mining industry. Conclusions: Since 1997, both number of workers employed in mining and disease and illness rates have decreased; however, the highest disease and illness rates in mining continue to be coal worker's pneumoconiosis and hearing loss.

By G. R. Leverant

RECENT investigations1,2 of the low-cycle fatigue behavior of pure copper under strain cycling conditions have shown that a unique saturation stress level is eventually attained for each value of applied plastic strain amplitude. The dislocation substructure of copper at the saturation stress level is in the form of cells whose diameter decreases with increasing saturation stress level, i.e., plastic strain amplitude. In addition, both the saturation stress level and the cellular substructure are completely reversible. That is, the saturation stress level and accompanying cell size are determined solely by the present conditions of testing and are, therefore, independent of any previous cyclic history. The mechanical and substructural reversibility observed in pure copper, which has a relatively high stacking fault energy, is not observedz for Cu-7.5A1 which has a much lower stacking fault energy. This implies that easy cross slip (wavy slip) is a prerequisite for reversible fatigue behavior. A dispersion of fine, nondeformable particles of a second phase in a metal matrix tends to stabilize substruc- tures introduced by forming operations during subsequent elevated-temperature heat treatments.3 This raises the question as to whether a finely dispersed second phase can induce an element of irre-versibility into the cyclic deformation behavior of a wavy slip material at room temperature, due to partial stabilization of the initially introduced substructure. Since nickel has a higher stacking fault energy than copper,6 pure nickel should be characterized by cyclic reversibility. Therefore, TD-nickel* (Ni-2ThO.r) was

Jan 1, 1968