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By T. Lenarcic, R. Svrkota, J. M. McNeal, E. Prohic, S. Pirc

Paper presented at the 28th International Geological Congress held in Washington DC, July 1989 (International geochemical mapping sessions). Surface drainage samples, the usual media employed in mapping national territories, cannot be used for the geochemical mapping of carbonate terrains because there is no regular surface-drainage pattern on karst. Suitable sampling media have been studied in Yugoslavia, one-third of which consists of karst terrain. Sampling designs for the work were based on analysis of variance techniques. During initial investigations of various sampling materials in NW Yugoslavia sediment and aquatic moss from karst springs, along with soil, were established as the most appropriate media. Modified sampling procedures were then carefully applied along the entire Yugoslav karst belt, which includes terrains of contrasting topography, climate, pedology and vegetation. The studies indicate that climate and relief do not systematically influence the geochemical composition of soil. Regional and local variability was assessed for 21 chemical elements and the feasibility of producing stable regional geochemical maps was determined for a number of elements on the basis of sampling aquatic moss and sediment from karst springs and soil

Jul 1, 1991

By H. Agnerian

"A survey of 925 mineral property transactions worldwide was carried out between 1987 and 2004. These mineral properties with reported Mineral Resources include 457 gold properties, 322 base metal properties, and five platinum group element (PGE) properties. Based on constant Canadian dollars, the results of the survey indicate that:• In general, unit metal values in the ground (e.g. $/oz Au or $/lb Cu) have kept pace with the changes in the respective metal prices during the period of the survey.• A general decrease in unit gold values in the ground has occurred from about $57/oz Au in 1987 to about $11/oz Au in 2002 for Canadian mineral properties, with the exception of a peak of $58/oz Au in 1996.• A similar trend for mineral properties has occurred in the United States, but with lower unit values, in the range from $1/oz Au to $10/oz Au during the last three years of the survey. • Unit metal values in the ground for gold properties in Canada were higher than for those in the rest of the world.• Unit metal values in the ground for copper properties in Canada were in the mid-range compared with other countries in the rest of the world; the United States and Australia were higher and Latin America, Asia, Africa, and Europe were lower than in Canada.• Unit metal values in the ground for zinc properties in Canada were also in the mid-range compared with other countries in the rest of the world; Latin America and Europe were higher and the United States, Australia, and Asia were lower than in Canada.• Unit metal values for nickel properties in Canada were highest compared with other countries in the rest of the world, followed by the United States, Australia, Africa, and Asia.• Gold values in the ground in Canada have ranged from 6% to 14% (with an average of approximately 10%) of the gold price.• The unit values of base metals in the ground have been in the order of 2% of the quoted metal price, during the period of the survey."

Jan 1, 2006

By C. L. Reichardt

Mining companies are increasingly looking to the developing world for the next generation of mining projects, often in countries that have little or no previous history of large-scale mining. One of the major challenges for such projects is hiring?and retaining?personnel that have technical skills and experience in mining-related disciplines. Staffing a mine with an expatriate workforce is neither cost-effective nor sustainable, and many countries now insist that mining companies ?transform? the profile of their workforce to more closely mirror the demographic profile of the host population. The need to nurture mining-related skills in emerging mining nations is not solely limited to the workforce: there are also pressing economic and sustainability imperatives to develop capacity within local service providers such as consultants and contractors, as well as to facilitate informed engagement between mining companies, government and civil society. However, few educational institutions in emerging mining nations currently have the ability to offer practical training in mining-related disciplines. Local employees who are sponsored by companies to develop their skills through international study maybe impeded by language and cultural barriers, and may also be taught using course content that is of limited relevance to the specific challenges of their future working environment. This paper addresses the challenge of skills development and retention in emerging mining nations and uses examples from sub-Saharan Africa and the Asia Pacific region to explore practical means of developing capacity in mining-related disciplines. It examines the need for companies to implement strategies to develop local technical capacity in countries where they envisage a long-term operational future and also highlights the need to foster partnerships between academia, developmental institutions, mining companies, governments and civil society to establish the critical mass of mining-related skills required to nurture the development of a sustainable mining industry.

Jan 1, 2009

By Anna M. Ferrero

Stability condition of underground excavations have to be assessed to guarantee safe operations within the quarrying working areas. This objective requires a reliable assessment of the rock mass natural state of stress and of the stress redistribution induced by the excavations. This goal is often complicated by difficult geological conditions induced by tectonic stresses, complex topographies and large and irregular excavation geometries. Consequently, the acting state of stress needs to be measured by specific in situ measurement devices. This work refers on an in situ measurements campaign carried out by CSIRO tests in an underground quarry located in the Carrara marble basin. The difficult path carried out for interpretation of the measurements is described in this paper. In particular, the numerical modeling performed using the Boundary Element Method (BEM) first, to study the influence of both surface topography and excavation geometry and then the Distinct Element Method (DEM) to evaluate the influence of rock discontinuities in the measurement zone are illustrated in this work. Parametrical analysis of the rock mass mechanical features is also described in order to calibrate the numerical models and analyze the experimental results. The work has been carried out trough several phases, which are: characterization of the rock mass through geostructural surveys: this allowed us to classify the rock mass and determine the mechanical and physical parameters necessary for modeling; on-site measurement of stress levels through the application of over coring techniques; numerical analyses for the simulation of excavation phases, using the Examine3D (BEM) engineering analysis code. comparison between the measured stress levels and those numerically calculated and subsequent calibration of the BEM model; Numerical model of the forecasted excavation based on the calibrated (BEM) model.

May 1, 2009

INTRODUCTION ò World coal production, Exporters and Importers òNew Zealand Exports, Markets and Products ò Types of Markets and Price Setting ò Bench Mark Prices and Exchange Rate ò Transport ò International Marketing - Key Factors ò Coal New Zealand , the Challenges

Jan 1, 1996

By W. L. Cornell

The Missouri lead ores are the only domestic sources of cobalt presently being mined and processed for other materials. They represent the best short-term solution for meeting up to 13 pct of the Nation's strategic and critical cobalt needs from domestic sources. Presently, the cobalt is lost as an impurity in the copper, lead, and zinc concentrates and in the mill tailings because the technology to recover it with minium impact on present production does not exist. This paper presents results of research, built upon earlier Bureau of Mines laboratory research, to enumerate the problems encountered in cobalt recovery from the copper concentrate under actual mill conditions; to present alternative solutions to these problems; and finally, to describe the best available technology for cobalt recovery within the imposed constraints. Mineralogical analyses showed the cobalt present as a distinct mineral phase, predominately siegenite, amenable to a physical separation method such as froth flotation. Flotation was chosen for recovery because of easy adaptation by the mills. Unit processes of grinding, conditioning, and flotation were studied individually and in concert, and a series of continuous tests were run based on the parameters developed to obtain engineering data for subsequent economic analysis. Overall cobalt grades of 3.00 wt pct at a recovery of 64.0 pct were achieved.

Jan 1, 1987

By Tracy Brettmann

The use of rock-socketed Augered Cast-In-Place (ACIP) piles is new to the Austin and central Texas region. This case history describes the design methodology, load test results, quality control procedures and the rate of production pile installation for the first large commercial project where ACIP piles were used in Austin. The piles were 24 inches in diameter and extended through about 45 ft of alluvial materials to be socketed 6 ft into limestone. A full-scale instrumented load test was performed on a test pile that was loaded to 452 tons and held for 24 hours. Telltales were installed in the middle and the tip of the test pile. As part of the overall quality control procedures, singlehole sonic integrity logging was performed on the production piles to verify structural integrity during pile installation. During pile production, an average of 14 piles per day were installed, which is approximately seven times faster than the original design that consisted of drilled shaft foundations.

Jan 1, 1998

By F. M. C. C. Vieira

The DEEPMINE Research Programme sought to develop the technology and competence to mine gold safely and profitably at depths of 3 to 5 km. Among the many issues addressed was the stability and support of rockpasses at ultra-depth. It was found that high virgin and mining-induced stresses could cause the walls of rockpasses to spall, leading to the deterioration and failure. A comprehensive programme of numerical modelling was conducted to investigate alternative mining layouts and sequences to ameliorate the problem.

Jan 1, 2005

By M. B. Shongwe

Pt-based alloys are being developed for high-temperature applications with the aim of replacing some of the currently used Ni-based superalloys (NBSAs) in the highest temperature applications. The Pt-based alloys have a similar structure to the NBSAs, and since Pt is more chemically inert than nickel and has a higher melting point, they can potentially be used at higher temperatures, up to 1300°C, and in more aggressive environments. Several experimental Pt-based alloys were studied at Mintek, and an optimum composition was found to be Pt84:Ahi:Ru2:Cr3 (at.%). On the basis of hardness and microstructure, a later study identified a new optimum: Ptr8:A111:Ru5:Cr6 (at.%). There are at least two Pt3A1 allotropes, and the high-temperature cubic structure has better properties than the lower temperature tetragonal form, and so needs to be stabilized. This work describes the latest results obtained in transmission electron microscopy (TEM) studies of the quaternary Pt-based superalloys. These results are both interesting and important, because the samples have a higher precipitate density compared to those from earlier work. The precipitate morphology is mainly cubic, with minor areas having irregular-shaped precipitates. The high volume fraction of the precipitates is a major breakthrough, since the objective of this work is to improve the alloys. A prior disadvantage was that the proportion of the precipitates was too low in samples before this work, especially compared with the work from Germany on Pt-Al-Cr-Ni¬-based alloys as well as the NBSAs. TEM -Pt3A1 diffraction patterns were studied, and for each diffraction pattern, many possible lattice point combinations were tried, with the angle between the lattice spots as well as interplanar spacings being calculated for each phase (cubic or tetragonal) to match the measured results. An overall analysis of the diffraction results indicates that the cubic phase fitted the experimental lattice points with much lower errors compared to the tetragonal phase. Thus, with the close match achieved with the cubic structure, the structure of -Pt3A1 precipitates is likely to be cubic. X-ray diffraction has been carried out on selected samples, and the results confirmed the presence of cubic -Pt3A1 and (Pt). Different X¬ray diffractometers were used to further verify the results, and the results were also compared with those from TEM.

Jan 1, 2012

IN 1906, soon after his arrival in New Zealand, a brief article was prepared by the writer on "The Salient Features of the Economic Geology of New Zealand," for the Journal of Economic Geology. In November, 1907, a somewhat similar paper, entitled "The Mineral Wealth of New Zealand," was read at the Royal Colonial Institute in London. The present contribution to the Transactions...

Jan 1, 1909

The contiguous Kotre Basantpur and Pachmo (KBP) coal blocks in the Hazaribagh District of Jharkhand State in east India are being developed by Tata Steel Limited (Tata Steel) to supply coking coal to a new steel mill at Kalinganagar in Orissa.The planning challenges are many. The multiple coal seams range in thickness up to 6 m and extend to nearly 500 m depth, with dips up to 25¦ and highly variable quality. Several normal faults with throws up to 150 m intersect the deposit. There is little room for waste dumping on the lease, several large nalas (seasonal creeks) cross the blocks, and the KBP leases are not contiguous with Tata Steel's existing mining operations at West Bokaro. Geotechnical conditions, while not well defined at this stage, are largely unfavourable. There are several villages on the blocks, and extensive paddy fields. In 2009, Adelaide Mining Consultants Pty Ltd (AMC) completed a Detailed Project Report (DPR) for a production level of 8 Mt/a. A terrace mining system was proposed using 28 m3 hydraulic excavators and 185 t trucks working horizontal up-dip slices. Subsequently the viability of in-pit crushing and conveying was assessed, but the full results were not available for this paper.It is planned to extract a total of 147 Mt of raw coal at a strip ratio of 5.2 bank cubic metres per tonne (bcm/t). The planned maximum pit depth is over 300 m.The project includes a washery, a 2 + 25 MW fluidised bed power station to utilise all the coarse washery rejects, and a railway spur line to carry the washed coal to the railhead some 7 km distant.

Dec 6, 2010

By Patrick E. Durnal

The Richmond-San Rafael Bridge was built in the early 50s' and was first opened to traffic on August 31, 1956. Among California's longest steel bridges, it spans more than 21,000 feet across the northern portion of San Francisco Bay. It is one of six toll bridges currently undergoing seismic retrofit in the Bay area. Current retrofit criteria require the structure not to collapse in a Magnitude 8.3 earthquake lasting 45 seconds on the San Andreas Fault. The earthquake epicenter is 10 miles to the west of the Bridge, near the mouth of San Francisco Bay. Another major fault is the Hayward Fault, with a potential of a 7.5 magnitude earthquake. It is only 4 miles east of the eastern end of the bridge. The retrofit criterion is that the structure survives these earthquakes without collapse or loss of life, and that they are capable of repair within a period of one year. Therefore an energy absorbing, ductility and nominal resistance based approach to the retrofit design have been adopted for the retrofit of this bridge. Foundation Retrofit The foundation retrofits were designed to satisfy of drift criteria of 6 inches at the base of the footings, and to keep the existing H-piles from experiencing unacceptable levels of permanent soil displacement and /or structural rupture. Full-scale structural lateral load testing of BP14x89 piling, to rupture, has helped to determine the drift criteria. However recent non-linear analytical results, have led to a redesign, which may allow for 12 inches of drift. The as-built analysis of the Micropile piers determined that those piers would not exceed the 6-inch drift criteria so lateral resisting shear piles were not needed at those piers.

Jan 1, 1998

By E. A. Gulbransen, K. F. Andrew

THIS paper. will present the results of our studies on the kinetics of the gas phase reactions of co-lumbium and tantalum with O2, N2 and H2. Studies on zirconium and titanium have been previously reported.9,11 Due to their high melting points and their many excellent physical and chemical properties, colurn-bium and tantalum have been finding their places as useful metals in science and industry. Chemically the metals are very inert to gas and liquid phase corrosion at room temperature. However, at moderate temperatures of 250°C and higher the metals react readily with oxygen and hydrogen. It is of interest to study the gas phase reactions of these metals for the following reasons: (1) to compare the rates of the several reactions with those of other metals and to correlate the rate data with theory and structure predictions, (2) to add basic information on the practical difficulties of the reduction, refining and working of columbium and tantalum, (3) to anticipate new uses for the metals and (4) to understand the role that the metals play as components in high temperature alloys. Literature Survey A number of papers exist in the literature on the gas phase reactions of columbium and tantalum with O2, N2 and H2; however, only fragmentary data have been reported on the kinetics of these reactions. Although the free energy of formation of the oxide Ta2O520at 25°C has been determined and some thermodynamic work has been reported on columbium and its oxides, the data are not sufficient to make equilibria calculations at elevated temperatures. Oxidation: 1. Kinetics: The rate of oxidation of columbium and tantalum has been studied by McAdam and Geil23 using the interference color method. Tantalum is reported to oxidize more slowly than columbium, zirconium and iron. The amounts of oxidation of columbium after 20 hr in air for several temperatures are reported by the Fansteel Metallurgical Corporation.36 Columbium starts to oxidize in air at about 200°C. The oxide is said to be adherent and prevents further oxidation until the temperature is raised. Columbium is reported not to become brittle on heating in air for short periods like tantalum because the oxide film prevents further reaction. The columbium oxides dissolve into the metal when heated in a vacuum at temperatures between red heat and 1200°C. Above 1200°C the oxides are reported to evaporate. Columbium, in the oxide free state, is an active getter in vacuum tubes. 2. Preparation and Structure: G. Grube, O. Kuba-schewski and K. Zwiauer15 have studied the decomposition of Cb2O5 in argon. They find that CbO2 is formed slowly at 1150° and rapidly at 1300°C. Cb2O5 can be reduced to CbO2 by moist H2. The reduction of this dioxide to the lower oxides is rapid. By varying conditions CbO2, Cb2O3, CbO and Cb2O can be formed. CbO2, CbO and Cb2O have independent lattices while Cb2O3 is a stoichiometric mixture of CbO and CbO2. In a later paper O. Kuba-schewski" has shown that CbO is cubic and that CbO2 has a rutile type of lattice. The most exhaustive work on the oxides of columbium is that of G. Brauer.8 The number and constitution of the solid phases in the binary system Cb-O were investigated by the preparative, analytical and X ray methods. He indicates that only the oxides Cb2O5, CbO2 and CbO exist with limited regions of homogeneity. The solid oxide Cb,O, exists

Jan 1, 1951

By Mark E. Hammele

A number of new thoughts have recently emerged concerning the role of air decks, stemming, gas confinement and gross motion in specific blasting environments and applications. Field research in full-scale production environments is based on the theoret ical work f i rst proposed at the Universi ty of Maryland’s Fracture Mechanics Laboratory.

Jan 1, 1989

By Eduardo Nunez, Asim Tuzun, Dan Graffi, Glenn MacPherson

"In preparation for the milling of a new nickel and copper mine ore, Nickel Rim South, Xstrata’s Strathcona Mill is undertaking numerous process improvement projects. Within the grinding circuit, several projects are under development and an automated grinding control strategy, consistent with the operating objectives, was identified as a key requirement. The grinding strategy is to maximize the throughput (quantitative objective) while maintaining the cyclone overflow within specifications (qualitative objective).This paper describes the implementation of a robust grinding control strategy using the existing control system. The implemented controls maintain the cyclone overflow density at the desired target, while continually optimising the rod mill feed rate to allow maximum throughput. This approach has the added benefit of improving the stability of the rougher flotation circuit down stream of the grinding and improving energy efficiency of the rod and primary ball mills. This paper discusses the comparison of the before and after the implementation of results.INTRODUCTIONThe grinding process is a size reduction operation used in the mining industry to liberate the valuable minerals from the gangue. Grinding is one of the most important and expensive processes in a concentrator (Xi-song, 2007; Pomerleau 2000; Najim 1995), often accounting for around half of the total operating costs in base metal concentrators (Wills, 1990), which has led to a focus on development and implementation of control and optimisation strategies. The grinding process prepares the ore for the subsequent concentration step, which for sulphide base metal operations, is predominantly flotation. The performance of the concentration (flotation) is very much determined by the feed characteristics of the slurry coming from grinding. The valuable minerals recovery process in flotation is very much influenced by the grinding process and the liberation of the desired minerals from the gangue minerals (McIvor, 1991).The true objective of grinding is to obtain a proper liberation of the minerals as defined by a particle size distribution referenced typically by d80 (80% passing size of product). Besides achieving the desired mineral d80 size, it is clearly desirable to produce as narrow a size distribution as possible to squeeze the maximum amount of the mineral value into the highest recovery region (McIvor, 1991). This is an important criterion for the mill in economically optimizing the grade and recovery for the concentrate product. It is important not to over or under grind, while keeping the specific comminution energy as low as possible (Nunez, 2005) to achieve the target liberation. In other words, maintain an optimal throughput depending on the ore conditions to the capacity of the grinding mills, while providing the flotation process with a constant and narrow size distribution, at a cut size selected to meet the metallurgical requirements (Bascur, 1991)."

Jan 1, 2009

By J. J. Wallace

This report describes the initial phase of Bureau of Mines research in the hydraulic mining of bituminous coal. The mining site and equipment are described, and the test procedures and results obtained with a bar-mounted monitor are given. Tests showed that hard Pittsburgh-bed coal can be mined hydraulically from a solid face at water pressures of 4,000 pounds per square inch.4 Coal was penetrated to a depth of 4 feet in 20 seconds with 225 gallons of water per minute coming from a 3/8-inch nozzle at 4,000 pounds per square inch pressure. Some difficulty was encountered in cutting the binders occurring in the coal; it was not possible Lu penetrate directly the overlying draw slate.

Jan 1, 1961

By Ycaro Jorge Maia da Costa

O desenvolvimento de estruturas com dimensionamento confiável requer o monitoramento de seus materiais, entretanto alguns processos de fabricação muitas vezes induzem modificações em seu comportamento mecânico. Isso faz com que as estruturas sejam menos confiáveis podendo causar redução da vida útil. Um dos processos onde isso acontece é a soldagem. Seu aporte térmico, modifica a microestrutura do material de tal forma a gerar três regiões mecanicamente distintas na junta soldada: Metal de Solda (MS), Zona Afetada pelo Calor (ZAC) e Metal de Base (MB), fazendo com que haja concentração de tensão na região afetada. Este trabalho se deteve em analisar o comportamento mecânico de uma junta soldada de aço inoxidável AISI 304 em comparação com o mesmo material não-soldado através da identificação dos gradientes de deformação, utilizando da Correlação Digital de Imagens (CDI) aplicada ao ensaio de tração. Os resultados provaram a capacidade da técnica de CDI em identificar campos de deformação mesmo em materiais anisotrópicos, como uma junta soldada.

Aug 17, 2017

By Vu Van Dong

Resource estimation is the science of determining the amount and quality of a given material in the ground that has the potential to be mined at a profit. This is because during this time computers have become more widely available and more powerful and software packages have become more comprehensive and user friendly. Over the past three years The Mining Geology Company with the support from Vinacomin Group has developed the Coal Geological Modelling and Reserve Estimation ? VMG system. The VMG system enables the geological and mining engineer to start at the reserve estimation for the mine design and planning. The VMG system enables the national and international standards (NI43-101, CIM-Canada; SAMREC Code, Africa, and JORC Code, Australia) and user friendly with menu driven thereby permitting the engineer with minimal computer training to rapidly learn and utilize the system. Geological and mining data input through digitized map files and drill-holes information files stored in the database that is an integral part of the VMG system with the main function for collection, validation, and recording, storing and processing of data will include both ?primary? (observation and measurement) and ?interpreted? data. It is recommend that data be stored digitally, using a documented, standard format and a reliable storage medium that allows for easy and complete retrieval of the data. The coal reserve estimation through standard polygon methods with the increased use of these mathematical techniques (geometrical modelling, geostatistical method, least square method, ?) over the last ten years corresponds, to some degree, to a decrease in both the amount of the coal deposit mapping and, in particular, coal seam structural interpretation and modelling, and permit rapidly evaluation of coal seam and overburden quality and quantity. The understanding of the relationship between the coal mineralization of interest and the likely related complicate geological processes and structure that govern its emplacement and geometry within the geological framework is essential to the establishment of the geological controls for coal mineralization. System outputs includes: drillholes summary reports, stratigraphy, cross-sections, isopach maps, structure, contour maps, premining and post mining topography maps, and 3D perspective view on coal seam structure.

Oct 1, 2009

By G. B. Harris, A. R. Laplante

Fine tungsten was used to mimic gold and fine and coarse silica and magnetite to mimic gangue. The optimum flow rate of fluidisation water varied from 1.7 l/min for fine silica to 5.6 l/min for coarse magnetite. Overloading at optimum flow rate was then investigated. With fine silica gangue no overload occurred under any of the conditions studied, and there was very little overload with fine magnetite. Coarse silica caused appreciable overload, but only after a significant bed of tungsten had been formed; with fine magnetite gangue the onset of overloading occurred earlier. Finally, with coarse magnetite severe overloading occurred almost immediately. Overloading was modelled using a first-order kinetic rate constant for erosion of the concentrate bed and a critical mass of constant above which it takes place. The results clearly demonstrate the importance of removing oversize to maximise recovery, particularly with a high-density gangue

Jun 18, 1905

Shortly after Denny, Robson, and Irwin published their first paper in 1937, on the prevention of silicosis by metallic aluminium, experiments were begun on the practical application of the discovery.It was thought at that time that aluminium powder, to be effective in aluminium therapy, would have to be intimately admixed with siliceous dust at the latter's source. There followed several years of experimental work underground, during which the application of aluminium powder was tested in:(1) Speakers on machine columns, vibrated by drills.(2) Vials placed in drill holes to be blasted.(3) Both homogeneous and heterogeneous mixture with explosives.(4) Packages with tamping.(5) Compressed-air lines.(6) Special compressed-air ejectors for use while drilling and after blasting.(7) The discharge of ventilation fans.(8) The filters of respirators.It was concluded from this research that any adequate method of introducing aluminium powder into a mine atmosphere would require too much extra gear, supervision, and aluminium p;wder, and would interfere unduly with underground routine.Later, animal experiments by Denny, Robson, and Irwin2 showed that aluminium powder provided effective therapy when inhaled independent of silica dust. Therefore, some means of surface treatment was deemed more practical.APPARATUS USED IN THE DEVELOPMENT OF ALUMINIUM PROPHYLAXIS SAMPLINGA basic requirement was a method of sampling to assess accurately the particle-size concentrations of dispersed aluminium powder. Konimetry, though regularly practised at McIrityre, was inadequate for the research in mind. On the other hand, the efficiency of the thermal precipitator was recognized as being very high. Accordingly, the latter instrument was chosen as best suited to our needs. Through the courtesy of the Ontario...

Jan 1, 1945