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By Brian D?Olier

Much of the aggregate that is being exploited at present from these areas is a ?relic? deposit. It was originally eroded from primary source rocks and transported to a depositional centre by processes that are now either greatly reduced in effectiveness or are largely absent at the present time. Following the retreat of the Devensian ice sheet, the subsequent rise of sealevel and the drowning of large areas of the continental shelf along with the lower reaches of many rivers, a fresh sequence of sediment sources, pathways and sinks now exist. Sediment is being eroded from several, pre-existing source areas and transported along different, well - defined pathways to a number of new depositional sinks. Some of the present, licenced, aggregate dredging areas lie close to these sources, pathways and sinks with the consequent dredging activity being perceived by some as interfering with the ?natural process? that links the offshore and the coastal / littoral zones. With this perception in mind, the principal, sources, pathways and sinks between Flamborough Head and Beachy Head will be highlighted and the relationship of dredging activity upon them, evaluated. It will be demonstrated that offshore dredging activity has no effect upon supplies of sediment to coastal beaches.

Jan 1, 2004

The cement industry requires large quan- tities of limestone, its main raw material. It is the major consumer of this mineral. Limestone is widely distributed throughout Australia but location in relation to major markets, and transport considerations render most deposits of no economic value. Of those which are sufficiently close to the major me- tropolitan markets many are rejected as being unsuitable on grounds of quality, inadequate size for major development, or other reasons such as environmental considerations. Detailed geological investigations are necessary, not only to prove raw material sources prior to establishment of a cement works but also to permit planned extraction programmes and satisfactory grade control during subsequent development. Conventional field techniques have generally proved adequate for raw material exploration. Data assessment and reserves estimation also are by conventional methods although the specific requirements of the industry relating to raw material and cement quality, the type of manufacturing process and fuel used are relevant. A number of case studies from different geological environ- ments are examined and comparisons made bet- ween the predictions of the exploration stage and subsequent experience in quarrying prac- Tice.

Jan 1, 1979

By Charles Tkaczuk

Key issues ? No business tool has greater potential to effect change and enhance profitability than process control. ? Successful businesses see process control as an integrated engineered system, designed and built into their business models from day one. ? The integration and use of process control sets the stage for years of compounded returns. ? Has been used for years to optimizing recoveries and minimizing waste. ? However, the mining/ore extraction sector has been slow to adopt integrated process control. What is the problem? ? Most executives and engineers do not clearly understand process control when applied to mining/extraction activities. ? Common approach has been to apply generic process control strategies as a blanket cure all and wait for it to pay off. ? No central focus which results in multiple group involvement, overlap and inconsistent application of questionable technology. ? Considered a low priority until production activities commence. ? Comfort in using brute force mining methods. ? An off-the-shelf integrated under ground mining process control architecture has not until recently been available.

May 1, 2004

By G. E. McElroy

The purpose of tins paper is not to present new date on the pressure losses due to bends and chances of area in mine openings through which air flows, but rather to correlate existing data, determined mainly on small duct systems and expressed in a variety of ways, according to uniform methods that facilitate their use in pressure-loss computations. These are required in such, air-flow problems as determining the quantity that will flow through is mine openings under a certain pressure difference or, conversely, the pressure difference that will be required to maintain a certain rate of flow. Air flowing through h ducts, such as mine airways, encounters resistance to flow due to interference of the individual air streams with each other caused by the wall surfaces. The result is that part of the kinetic energy of the flowing stream is converted to heat; and constant renewal of the kinetic energy from the total energy of the flow is required to maintain it. This process manifests itself by a decrease of the total pressure (static pressure plus velocity pressure; of the air in the direction of flow; in order that flow pray occur, there must necessarily be a differences in total pressure between the two cads of the air-ay equivalent to the pressure losses occasioned by the flow, which automatically adjusts itself in magnitude to the pressure difference maintained.

Jan 1, 1932

By R. R. Culbert

Several thousand parts per billion of uranium are present in some alkaline lake and ground waters of the Okanagan region, British Columbia. To a major extent the uranium content of these highly anomalous waters is controlled by their levels of dissolved bicarbonate. In lakes, dissolved bicarbonate and the organic content of the sediment largely control the partitioning of uranium between sediment and water. This relationship is found to a lesser extent in alkaline creeks, and transported geochemical anomalies in soils appear where uranium-bearing alkaline ground waters have encountered organic materials. There is a possibility that young, near-surface deposits (with very low radioactivity) are forming from these uraniferous waters.

Jan 1, 1978

By David J. Howard, Christine Broadbridge, David C. Paine

"High pressure vapor/solid reactions offer an opportunity for novel synthesis and processing of thin film materials and structures for electronic, optical, and magnetic applications. In this paper we review the use of two high pressure techniques that operate from 25 to 1000 atm (2.5 to 100 MPa) to fabricate thin film oxide structures from Si1-xGex deposited on Si wafers. High pressure synthesis enables temperature-independent control of reaction rates in the oxidation of this multicomponent semiconductor system and hence offers the opportunity to form thennodynamically metastable Si1-xGex<h from the alloy. The thermodynamics of the Si-Ge-0 system are reviewed and a method is described that utilizes selective chemical reduction (via H2 gas) of Si1-xGcx<h to form Ge precipitates in an SiO2 matrix. IntroductionAlloys of Si1-xGex grown epitaxially on Si substrates by chemical vapor deposition (CYD) and molecular beam epitaxy (MBE) have been used to create high performance microelectronic devices1. These devices show improved performance over conventional Si technology because they exploit the Si/Si 1-xGex band-gap discontinuity and take advantage of higher hole mobilities in the Ge containing alloys. While a range of devices based on heteroepitaxial systems have been demonstrated, the Si1_xGex alloys are of particular interest because they are most closely compatable with standard Si device processing. One disadvantage of Si-based materials systems is that they are not typically useful emitters of light. This is important since the use of light (rather than electrons) for transmitting and processing signals into, out of, and within Si-based microelectronics would represent a major technological advance in microelectronics-based communication and computer technologies. Nevertheless, through the use of innovative processing techniques it may be possible to use the Si1_xGex/Si heteroepitaxial system in integrated microelectronic/light-wave technologies."

Jan 1, 1994

By Q. G. Reynolds

The dual-electrode DC arc furnace, an alternative design using an anode and cathode electrode instead of a hearth anode, was studied at small scale using computational modelling methods. Particular attention was paid to the effect of two key design variables, the arc length and the electrode separation, on the furnace behaviour. It was found that reducing the arc length to brush arc conditions was a valid means of overcoming several of the limitations of the dual-electrode design, namely high voltages and arc deflection.

Jan 1, 2012

By Gordon Revey

In construction and mining work, situations occasionally occur where hard rock or concrete must be excavated at locations near critical structures or utilities. Fearing damage from blasting, contractors and engineers often explore the viability of using mechanical methods or expansive concrete to facilitate the excavation work. However, for moderate to large excavations, the prolonged duration and high cost of using these methods is often impractical. In these situations, under the right conditions, controlled blasting and blast-management methods can be used to speed up the work and lessen costs. The process of determining whether or not blasting is practical is ofien complex, particularly when risks are high.

Jan 1, 2001

By B. W. Christ, P. M. Giles

Mossbauer effect measurewents have been made on I-mil-thick foils of commercial 1 wt pct C steel and Fe-2 wt pct C alloy. The experimental method required about 3 to 5 vol pct of a phase in the nzultiphase steel sample for detection. Room-temperature Md&apos;ssbauer patterns obtained on austenitized atid quenched samples exhibit fifteen, and possibly twenty-one, lines. A sharp parama&tetic singlet and a quadrupole doublet, poorly resolued from the singlet, are attributed to austenite. Remaining lines are due to tnartensite. Accurate evaluation of austenite line paranzeters is not feasible if significant amounts of other phases such as carbides or martensite occur simultaneously with austenite. This is demonstrated by comparison of hyperfine interactions determined for austenite in multiphase high-carbon samples with those reported for Fe-C austenite in a nearly 100 pct austenitic sanple. Lines from carbides are incompletely resolced from austenite lines, as demonstrated by comparison of austenite line positions with carbide line positions calculated frow published values of hyperfine interactions. One martensite line overlaps an austenite line in the pattern for commercial 1 wt pct C steel. Results of this study suggest that the usefulness of e M6ssbauer pectroscopy for quantitatizle analysis of austenite in bulk samples of quenched and tempered high-carbon steels is restricted by poor resolution. Use of Mossbauer spectroscopy for phase identification and for evaluation of atomic and electronic structures appears quite feasible, however, The Mijssbauer effect has been widely discssed,&apos;-and e Mossbauer effect measurements have been reported on materials of metallurgical interest.7"20 In particular, it has been proposed that e Mossbauer patterns of commercial steels and laboratory-made Fe-C alloys, in the quenched condition, are composed of lines originating in two phases, Fe-C austenite and Fe-C martenite.-&apos; Evidence accumulated in this study demonstrates that three absorption lines found in the central region of the e Mossbauer pattern obtained on quenched steels are attributable to retained austenite. This interpretation is supported by parallel decreases in the intensity of these three lines caused by subambient cooling of commercial 1 wt pct C steel samples after water quenching to room temperature. A second result of this study is to clarify effects of line resolution and sensitivity in the Mossbauer patterns of multiphase steels on the accu- rate determination of austenite line parameters. Experimental line widths (full width at half height) are generally 1.5 to 3 times larger than the natural line width of 0.19 mm per sec. At least two lines, and sometimes more, from a single phase such as cementite (Fe3C), other carbides, martensite, and austenite fall in the energy band, i0.85 mm per sec. hhis band width is employed simply for convenient reference. It represents approximately the energy interval between the + 112 to 112 transitions in ferrite and is expressed as the velocity needed to Doppler shift a 14.4kev 7 ray to the aforementioned ferrite energy levels. This energy band is referred to as "the central region of the Mossbauer atttern:: in this paper. Hence, due to the large number of lines from different phases in a multiphase steel falling in a relatively narrow energy band, absorption lines from the different phases may overlap. Analysis of available data, presented below, indicates that this occurs to a significant extent for phases which commonly occur in quenched and quenched and tempered high-carbon steels. One consequence of limited resolution in the Mdssbauer patterns from multiphase steels is difficulty in accurate determination of such line parameters as position, width, and intensity. In fact, it appears that quantitative analysis for retained austenite in quenched and tempered high-carbon steels is not practical with the present experimental method. Line resolution is influenced to some extent by sensitivity. We point out below that atom or volume fractions of less than about 3 to 5 pct are not detected by the present experimental method. Thus, the presence of a multiplicity of phases does not always lead to impaired resolution. Finally, we report in this paper room-temperature MGssbauer parameters determined for austenite in a freshly quenched, commercial 1 wt pct C steel and in a freshly quenched laboratory heat of an Fe-2 wt pct C alloy. These parameters are compared with others reported in the literature. Three types of hyperfine interactions are detectable in a Mossbauer effect measurement: isomer shift, quadrupole interaction, and magnetic dipole interaction. These interactions are evidenced by one, two, and six line patterns, respectively.&apos;-4 More than one type of interaction has been reported in certain metallurgical phases thus far studied by this method. Isomer shift is the experimentally measured displacement of line position from some arbitrarily defined reference position. In the case of a multiline pattern, isomer shift is given by the displacement of the centroid (center of gravity) of that pattern from the reference position. All isomer shifts measured at finite temperatures contain a second-order Doppler effect characteristic of that temperature. The isomer shift is related to the total s electron density at the nucleus, becoming more negative with increasing s electron density. The first-order quadrupole effect arises from the interaction between the nuclear quadrupole moment and any axially symmetric electric field gradient in

Jan 1, 1969

By D. Hugh Trollope, L. A. Fekete

L.A. Fekete (Project Engineer, Johnson B & Assoc. Engineers, Houston.) - The author tries to classify rock slopes in: a) homogeneous monolith, b) random, c) block-jointed systems. This may be practical at a specific mine, but it does not describe the mechanical behavior of the slopes in general. The difficulty with the problems of earth mechanics is the same, as with other structural problems: To

Jan 1, 1963

By S. S. Peng

To prevent mine floor heave, the mechanisms of floor heave must be fully understood. Based on the field study, the mechanisms of two types of floor heaves are analyzed in this paper. The mechanical models for the two types of floor heaves are developed. The floor heave can be predicted by the developed mechanical models and the control measures are recommended.

Jan 1, 1995

By David R. Shields, Michael T. Bracher

"The $330 million (U.S.) Dana-Farber Cancer Institute’s Yawkey Center for Cancer Care (Yawkey Center) sits in the heart of Boston’s Longwood Medical Area. The Yawkey Center is a cutting-edge cancer care facility that houses Dana-Farber’s adult clinical care and clinical research programs. Standing 14 stories above grade, it includes 7 stories of underground parking extending 75 ft (23 m) below ground. The structure is on a 198 by 186 ft (60 by 57 m) site sandwiched between Dana-Farber’s 13-story Richard A. and Susan F. Smith Research Laboratories Building, the Medical Area Total Energy Plant (MATEP), Jimmy Fund Way, and Brookline Avenue, a busy four lane artery through the heart of the Longwood Medical Area. Together with Simon Design Engineering, the project structural engineer, GEI Consultants designed an innovative foundation and excavation support system to isolate the building from ground vibrations generated by the adjacent MATEP power plant. In effect, the Yawkey Center is a 21-story free-standing structure that starts 7 stories below grade.The MATEP facility provides power for 9 million sq ft (840,000 sq m) of occupied space in the medical area. There are six 32-cylinder diesel engine generators in the facility that produce low-frequency ground vibrations in the 10 Hz range, similar to the natural frequency of typical building elements. The resonant response of the Yawkey Center building structure to these ground vibrations would affect the performance of sensitive medical research equipment and cause an unacceptable environment for clinical care.The soil profile at the site consists of stiff clay, fine sand, glacial till, and bedrock consisting of hard metamorphosed conglomerate. In-situ measurements of ground vibrations performed in boreholes showed that there was little attenuation of the vibrations with depth in the soil layers overlying the bedrock, but the vibration amplitude in the bedrock was markedly lower than in the overlying soil. Based on this data, an innovative foundation system was designed to support the building on bedrock located up to 110 ft (34 m) below ground surface, while isolating it from the surrounding soil. This was done by physically separating the below-grade parking garage floors from the perimeter foundation walls to create a free-standing structure supported on the bedrock"

Jan 1, 2012

By Smith Z, Huppert P, Charbucinski J

The paper describes a spectrometric method and apparatus developed for lithology logging in brown coal formations. The nuclear spectromet- ric technique developed is able to delineate coal/sand/clay seams. One requirement was to log inside drilling rods, as well as cased or open holes. The method described is based on combined natural gamma and gamma- gamma techniques using a spectrometric system for signal acquisition and subsequent computer based on-line data analysis and interpretation.

Jan 1, 1989

By J. S. Berber

Bastnasite is a natural fluocarbonate of the cerium group and affords an abundant and high-grade source of the lighter rare-earth elements. As part of a broad research program in rare-earth element technology, the Federal Bureau of Mines directed extensive experimental work to separating and purifying the rare-earth elements in bastnasite. By the use of a combination of techniques--classical chemical, ion exchange, and solvent extraction--the processing of a bastnasite concentrate to obtain the individual rare-earth elements, or groups of elements, was accomplished. A bastnasite concentrate, containing about 60 percent rare-earth oxides, was sulfated with concentrated sulfuric acid to eliminate the carbon dioxide, fluorine, and silica. Calcination at 1,200° F. made the gangue matter insoluble, thus permitting the separation of the soluble rare-earth sulfates. Essentially 100 percent of the rare-earth elements were recovered by this procedure. Since the rare-earth sulfate solution contained only trace amounts of nonrare-earth elements, subsequent separation procedures were simplified.

Jan 1, 1960

By Harry Perry

The Bureau of Mines is glad to have this opportunity to discuss its present Coal Research Program and its significance to the industry with a group which has for many years been representative of the coal producing community. We believe we have a dynamic program that will help our vast coal resources to find their proper place in the U. S, economy. The present coal research activities of the Bureau are conducted in three organizational subdivisions: Minerals Research, Mineral Resource Development, and Health and Safety. All investigations are carried out in Bureau research facilities located in different sections of the country, Since its creation by the Organic Act of 1910 and subsequent amendments, the Bureau has worked closely with the coal industry--first by providing assistance in mine safety for anthracite and bituminous coal mining, and since that time, in providing information on conservation, safety, mining, preparation, and utilization.

Jan 1, 1966

By R. W. Heckel

The densification of molybdenum powder by hot pressing has been studied as a function of time (up to about 3 x 104 sec) at pressures of 5000, 15,000, and 30,000 psi in the temperature range from 3700o to 1200°C. Excluding results below 2 to 5 x 10 sec, the density (D) - pressure (P) - time (t) data followed the general form:

Jan 1, 1965

By P. Klossek

It is estimated that China accounts for 94% of the world supply of rare earths (Roskill, 2011). This fact, together with the impact of China?s export policy, poses a substantial risk to the security of the rare earth supply as well as a rare earth price risk. This situation has motivated an increase in the number of rare earth projects under development, i.e., there are currently more than 440 worldwide (Technology Metals Research, 2012). However, economically and environmentally acceptable processing technology to produce tradable products from rare earths (e.g., separated rare earth oxides) is not freely available on the market at the moment. In this respect, a lot of research and development has been initiated on this topic, in academia as well as in industry. Using a proprietary model and scenario-based analysis, we studied the impact that the development of rare earth processing technologies would have on the rare earth market and the economic feasibility of rare earth projects mentioned before. The analysis showed that this impact varies depending on the technology type (e.g., technology can affect project production volume, cost structure or both) and the legal context of the invention (e.g., free or limited by patenting availability of a new technology). The effect of a technology which influences project production volume is not the same as of a technology which changes project cost structure. The impact of a patented processing technology differs from the impact of a processing technology which is freely available on the market. In the case of a new technology which is limited by patenting, its impact depends on the market position (?producing?, ?next-coming?, or ?not producing? project) of the patent holder. The paper contributes to existing research by studying the dependence of the expected micro- and macroeconomic impact of rare earth processing technology developments on the properties of a new technology (e.g., costs, legal framework etc.). By this means, the paper adds to existing knowledge and attempts to make the rare earths market more transparent and predictable from a perspective outside China.

Aug 1, 2013

By Oliver Q. Leone

Electrorefining tests using titanium-nitrogen alloys as anode material showed that no significant quantity of nitrogen was transferred to the cathode deposit. The nitrogen of the anode remained in the scale, and the titanium-nitrogen alloy was anodically insoluble in the electrolyte when the nitrogen content was 11 weight-percent.

Jan 1, 1966

By F Farías, D Villa

Codelco’s Salvador Project has been operating a block/panel caving mine for more than 50 years. This underground mining method dynamically mixes the ore and dilution. As a result, forecasting grades is difficult and achieving 100 per cent extraction of the reserves is practically impossible. A substantial volume of the ore mixed with dilution becomes remnant ore and remains to be subsequently extracted.A potential open pit mine is under evaluation at Codelco’s Salvador Project, which includes the extraction of remnant ore post-block caving extraction. An effective methodology has been implemented to estimate what is left behind once the underground mine has closed. A new mixing method using the Cellular Automata (Alfaro and Saavedra, 2004) approach has been used to allow estimation of the remnant ore with a sufficient level of confidence to be included as part of the open pit reserve.A remnant block model is created using elements such as in situ block model, drawpoint layouts, historical production records and the drawpoint extraction. Using this information, simulations of the extraction of the mine by month from 1959 to 2019 were completed, using different mixing scenarios and trying to replicate the tonnage and grade extracted.Finally, the remnant block model is categorised using a score card with four inputs to assess the risk of the estimation of this material into a category class (measured, indicated and inferred).CITATION:Villa, D and Far&#237;as, F, 2016. Remnant ore model generation and categorisation post-block caving extraction at Salvador Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 461–470 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By H. W. Graham

The young metallurgist of today who thinks casually of the technical literature of the steel industry might conclude that little has been published concerning the Bessemer process. This conclusion is true as relating to the last decade or two, but there is a fairly voluminous Bessemer literature in the period of 1860 to 1910. Since that time, however, an entirely new level of metallurgical knowledge of steelmaking has been reached; and the present paper is simply an effort to look broadly from this new level and to bring the recorded history of the process up to date. It is an effort to appraise the acid Bessemer method of steelmaking in the light of today&apos;s technical knowledge thereof. In this paper matters of history will be dealt with only insofar as they contribute to an understanding of today&apos;s situation. Attention will be directed to the apparent causes of past developments in seeking to perceive the true direction of trends now in existence and effective as bearing upon future developments. The paper will discuss the economics of the Bessemer process, but only to the extent that will bear upon the metallurgist&apos;s understanding of his responsibility. The problem of the quality of Bessemer steel will be reviewed and examples will be given of the technical data upon which the reasoning of the paper is based. Matters of engineering design, mechanical maintenance, operation and metallurgical investigation will be surveyed. Comparisons will be made between the Bessemer and open-hearth processes for the sake of clear and ready understanding. Production First of all it is considered logical and informative to show how much Bessemer steel has been and is being produced, and the relation of that production to the tonllage made by the open-hearth process. Table 1 shows the tonnages made by the two processes in representative years. It is to be noted that these figures are in net tons of 2000, lb., whereas previous to 1940 the Institute figures were compiled in gross tons. id open-hearth production and steel going into castings are included, since separated data are not available for the early years of the period covered. The ratio shown in Table I is merely the Bessemer tonnage for a given year divided by the open-hearth tonnage of the same

Jan 1, 1941