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By George Boucher, Simon Williams, Neil McBride

"The aim of these analyses was to utilise the latest available production information for the Wandoooperation to determine the optimal blasting parameters, costing’information and predicted results(fragmentation, muckpile shape and vibra.tton). Much of the data used as input was made availablefrom the information gathered during the excavation of the test pits during 1995. As with any“planning stage” analyses, many assumptions were required to fill gaps in the available data."

Jan 1, 1998

By E. R. Dean

A wire-feed mechanism has been employed to fabricute metal alloy film resistors to various sheet resistivities on oxidized silicon substrates. The effect of several thousand hours storage in air at elevated temperatures on the resistance and temperature coefficient of resistance is presented. Unprotected films of- sheet resistivity between 100 and 500 ohms per sq fabricated at 300°C substrate tenzperatures were unstable when stored at 150°Cfor extended periods. The higher sheet resistivity films exhibited the greatest instability; however, even the 100 ohms per sq films drijted excessively for device application. When stored at still higher temperatures, the normalized resistance increases to maximum, then decreases until a minimum value is obtained, then finally increases in resistance until open. The use of a protective overcoating of SiO has had considerable benejicial effects on the film stability, so that 250 ohms per sq films deposited on 300°C substrates are now stable after 1000 hr storage at 250°C and possess a temperature coefficient of resistance less than 200 ppm per C. The use of a low substrate temperature during depositon (100°C) enables the preparation oj resistors with very low tenperature coefficients of resistance (10 to 20 ppnl per 'C). However, these films are less stable than their higher substrate temperatuve counterparts. During extended storage, the resistance of the protected films always decreases with lower substrate films exhibiting larger normalized resistance decreases. This resistance decrease is accompanied by a linearly related increase in the temperature coefficient of resistance. The electrical behavior of these films may be explained by postulating That the structure of the films is in the transition region between thick continuous films and ultrathin island structure films so that the conductivity is the restlt of both electron scattering and tunneling-activated charge carrier creation between neighboring grains. The annealing behavior when thermally aged is the result of defect anneal, grain growth, and selective oxidation. TheRE is a considerable interest in thin metallic films for use as resistor elements in microelectronic circuits.1,2 These resistor films must be stable when exposed to elevated-temperature storage or operating ambient, possess low temperature coefficients of resistance (hereafter referred to as T.C.R.), and be of a high enough sheet resistivity to be useful. The resistivity and T.C.R. of a thin metallic film are determined by the structure and thickness of the film. Hence the stability of the film when exposed to stress would depend on the stability of the structure. The resistivity of a thin film is the result of the electrons' interaction with the lattice vibrations (electron-phonon scattering), scattering of electrons due to impurities, defects, and grain boundaries and specula reflection from the film surfaces.3' All of these effects serve to reduce the electron mean free path and result in a resistivity higher than the ideal bulk. In ultrathin films possessing essentially an island structure consisting of a planar array of aggregates separated by a few to a few tens of angstroms, conduction is dominated by a combination of tunneling and activated charge carrier reation. Thin films would be characterized by relatively low resistivity, positive T.C.R., and reasonable structure stability whereas ultrathin films possess unstable structures, negative T.C.R., and exhibit high resistivity. Feldman6 has investigated films intermediate between the two regions and postulates that the resistivity of a film in the transition region is composed of two linearly additive parts: that due to the resistance of the grains and that due to the gaps. The grain resistivity would represent the scattering of the conduction electrons by defects, surfaces, and phonon interaction while the gap term represents the tunneling contribution. For gold and platinum films, he found as the film structure becomes progressively less continuous, corresponding to thinner films, the absolute value of the T.C.R. becomes progressively smaller until negative values are observed with respective zero T.C.R.'s at about 35 and 150 ohm per sq, respectively. Recently the author7 investigated the behavior of a multicomponent alloy of nickel, chromium, and iron and found the T.C.R.'s of these films decrease with decreasing substrate temperature during deposition. The lower T.C.A. associated with lower substrate temperatures was attributed to an increased contribution to the total resistivity from the negatively temperature-dependent gap tunneling since it is well-known that thin films deposited on low-temperature substrates consist of a higher density of smaller grains than the same sheet resistivity films deposited on higher-temperature substrates. Under conditions of thermal anneal, the author found that, when various sheet resistivity films fabricated at 300°C substrate temperature are exposed to extended storage in air at 300°C, the thinner films increase in resistance until open, while the thicker films

Jan 1, 1967

By Frank E. Cash, John A. Johnson

"INTRODUCTION The operators of the Lake Superior district iron-ore mines have made tremendous progress in the past 25 years in the transportation of broken ore from the working places to the surface. This progress has paid divi¬dends in increased production and in lower accident-frequency rates. The trend has been toward more efficient use of mechanical and electrical power and abolishment of many of the backbraking tasks formerly required of min¬ers and trammers.ScopeTransportation of iron ore as described in this paper covers (1) movement from the working place to ore raises by scrapers, shaker,conveyors, and belt conveyors, and, loading underground cars from chutes or-by scraping from loading drifts; (2) underground haulage, which includes underground cars trains, locomotives, and tracks; (3) shaft station's and hoisting shafts, which. Includes dumping cars, storage-pockets; auxiliary storage trenches, and shafts; (4) hoisting, which consists of skips, cages and hoists; and (5) head frames, loading into railroad cars, and stock-pile haulage.The 19 underground iron-ore mines discussed in this paper, situated in the Menominee, Marquette, Gogebic, Guyana, Mesabi, and Vermilion iron ranges of Michigan, Wisconsin, and Minnesota., shipped about 9,000,000 tons of iron ore in 1945, which constituted 56 percent of the underground iron ore taken from the Lake Superior district."

Nov 1, 1947

By A. Golshani, M. Oda, K. Suzuki, T. Takemura

Anisotropic behaviours of OhshimaOshima granite were investigated by carrying out uniaxial compression tests, together with observations of microcracks under an optical microscope. The elastic modulus tensor of Oshima granite at 10 per cent strength,E10, were calculated using theoretically formulation of elastic modulus tensor in terms of the second-rank crack tensor for pre-existing open microcracks. Furthermore, with the assumption of orthorhombic elasticity, the nine moduli of Oshima granite E10were determined by uniaxial compression test. Twenty-onemoduli of samples, calculated without assuming any symmetry, also showed orthorhombic features. Direction of the symmetry axes agreed well with the orientation of preexisting cracks. Comparison of crack tensor-based formulation results with the experimentally determined one show that the anisotropy of elasticity of Oshima granite is caused by pre-existing open microcracks, not by pre-existing healed microcracks and also crack tensor formulation can be used, as a first-order approximation at least, to describe the anisotropy of Oshima granite induced by pre-existing open microcracks. ZUSAMMENFASSUNG: Das anisotrope Verhalten des Oshima-Granits wurde mit Hilfe voneinachsigen Kompressionstests und durch die Betrachtung von Mikrorissen unter einem optischenLichtmikroskop untersucht. Das Elastizitätsmodul von Oshima-Granit bei 10 Prozent Kraft E10wurde berechnet, indem man die Formulierung des Elastizitätsmodultensors, ausgedrückt alsRisstensor zweiter Ordnung theoretisch auf bereits existierende Mikrorisse angewandt hat.Außerdem wurden die neun Module des Oshima-Granits unter der Annahme orthorhombischerElastizität E10mit einem einachsigen Kompressionstest bestimmt. Einundzwanzig Stichproben,die ohne die Annahme irgendeiner Symmetrie genommen wurden, zeigten ebenfallsorthorhombische Merkmale. Die Richtung der Symmetrieachsen stimmte mit der Orientierungbereits vorhandener Risse überein. Der Vergleich der Ergebnisse der auf dem Risstensorbasierenden Formulierung mit der experimentell bestimmten Formulierung zeigt, dass dieAnisotropie der Elastizität von Oshima-Granit von bereits vorhandenen offenen Mikrorissenverursacht wird, und nicht von vorhandenen vernarbten Mikrorissen, und dass dieRisstensorformulierung auch zumindest für eine Annäherung erster Ordnung benutzt werdenkann, um die durch vorhandene offene Mikrorisse induzierte Anisotropie des Oshima-Granits zubeschreiben. RESUME: Les comportements anisotropes du granit d’Oshima ont été étudiés en réalisant destests de compression simple, et en observant les microfissures au microscope optique. Le tenseurdu module d’élasticité du granit d’Oshima sous une résistance de 10 pourcents, E10, a été calculéen se servant de la formule théorique du tenseur de module d’élasticité basé sur le tenseur defissures de second ordre des microfissures ouvertes préexistantes. En outre, sur base del’hypothèse de l’élasticité orthorhombique, les neuf modules du granit d’Oshima ont étédéterminés par des tests de compression simple. Vingt et un modules d’échantillons, calculés endehors de toute hypothèse de symétrie, ont aussi montré des caractéristiques orthorhombiques. Ladirection des axes de symétrie correspondait bien à l’orientation des fissures préexistantes. Lacomparaison des résultats de la formule basée sur le tenseur de fissures avec les résultatsdéterminés expérimentalement montrent que l’anisotropie de l’élasticité du granit d’Oshimaprovient des microfissures ouvertes préexistantes, et non de microfissures préexistantes referméeset que la formule du tenseur de fissures peut servir, au moins comme première approximation, àdécrire l’anisotropie du granit d’Oshima marqué par des microfissures ouvertes préexistantes.

Jan 1, 2003

By Douglas A. Anderson

Mine the Internet? You bet. Precious information resources are there to be found by those willing to explore. Of course, the stratigraphy and the exploration tools must be learned. This article is is designed to help learn those tools and how to find the information that can help the reader. However, beware the Internet. It can be addicting. On the other hand, information can be found that you never suspected. And users can make contact with people who might otherwise never have crossed their paths.

Jan 1, 1996

By M. V. Sowmya

Batch biosorption experiments were carried out for the bio-remediation of Cr (VI) ions from aqueous solutions using Serratia marcescens, a Gram negative, heterotroph and Gram positive bacterial isolates from a chromite mine. The influence of various experimental parameters such as contact time, pH, concentration of Cr (VI) ions and amount of biomass was evaluated with respect to the uptake of Cr (VI). The bio-sorption of Cr (VI) was found to be quite rapid and the percentage biosortion was found to increase with increase in the equilibrium chromium concentration. The free energy of biosorption of Cr (VI) was estimated to be in the range of -23 to -25 kJ/mol for the chosen bacteria. The uptake of chromium by the bacteria was confirmed by EDX and FTIR spectroscopy. As a follow up of this study, bacterial strains resistant to hexavalent chromium were isolated from a chromite mine in Karnataka, India and identified as Arthrobacter sp., Micrococcus sp. and Exiguobacterium sp. using 16s rRNA sequencing. The efficacy of the bacterial isolates for Cr (VI) uptake was assessed and over 90% bioremoval could be achieved for Serratia marcescens and Micrococcus sp. isolate. Possible mechanisms of chromium uptake by the microorganism are discussed. Keywords: bioremediation, hexavalent chromium, biosorption, bioreduction

Sep 1, 2012

By Alla D. Mah

Compilation of data on materials of metallurgical interest is one of the important activities of the Berkeley Thermodynamics Laboratory of the Bureau of Mines. Recent renewed interest in metallurgy of vanadium renders the present compilation a timely guide for experimentation to improve present methods or to develop better methods of extractive metallurgy. Thermodynamic data for vanadium and its inorganic compounds have been critically surveyed, selected, and compiled into one convenient reference from which information can be readily obtained for evaluating heat balances, determining trends, and establishing limits of metallurgical processes. By indicating the direction of experimentation, this report enables the saving of time, effort, and expense which would otherwise be necessary for trial and error experimentation. Much of the data has been obtained experimentally at the Berkeley laboratory. Other data were collected through an extensive survey of worldwide literature through April 1965. Estimates were made when no data were avail-able. Data on the vanadium halides was sparse, and the results derived from existing data were at times divergent. Some of the selected values for the halides may need modification as more or better experimental data become available.

Jan 1, 1966

By Arthur Baker III

The orebodies are long bedding-plane lenses of chalcopyrite and sphalerite, associated with garnetite masses. Most of the orebodies are within a 50-ft thickness of Cambrian limestone; other Paleozoic limestones and dolomites are locally metamorphosed but only slightly mineralized. Pre-mineral faults are numerous, but shallow folds were the main ore-localizing structures. JOHNSON camp is in the northwestern part of Cochise County, Ariz., about 50 miles east of Tucson. The nearest major mining districts are Tombstone and Bisbee, respectively 27 and 50 miles to the south, and the Superior-Miami-Globe-Ray porphyry copper group, about 90 miles northwest. Like many mining camps of the Southwest, Johnson camp is said to have been worked by the Spaniards. The first production on record was in the early 1880's, when an unknown amount of oxidized copper-silver ore in the Peabody mine was mined from replacement orebodies in the Pennsyl-vanian Naco formation. From 1904 to 1911 outcropping oxidized ores in the Cambrian Abrigo formation were worked, and an estimated 100,000 tons of copper ore were shipped. In 1912 the first large sulphide orebody of the district, the Republic Manto orebody, was discovered, and in the following few years some 250,000 tons of predominantly sulphide ore were shipped. The average grade of this ore was approximately 4.5 pct Cu, 6 pct Zn, 0.8 oz. Ag, and 0.001 oz Au. The Republic, Copper Chief, and Mammoth mines were the principal producers during this period. Mining ceased in the district after 1920, and until 1943 only small-scale leasing operations were carried on. In 1943 all the mines that had been productive were acquired by the Coronado Copper and Zinc Co., the present operators, and in the 10 years since that time the district production has amounted to approximately 350,000 tons of milling ore averaging 2 pct Cu and 6 pct Zn. Most of this ore was produced from the Republic and Mammoth mines, but since 1950 a large part of the production has been from the new Moore mine. The total known production from the district, then, is about 3/4 million tons of copper and copper-zinc ore of low grade. All of this ore was produced from orebodies associated with garnetite in the middle member of the Cambrian Abrigo formation. In addition to this known production, an unknown tonnage of ore was extracted from the Peabody mine orebodies that lie in the Pennsylvanian Naco formation. Published information on the geology of the district is limited. Aside from brief references in various mining journals, only three papers on the district have been published.1-3 One of these is a U. S. Bureau of Mines report on a diamond drilling program, one is a brief paper on the general geology of the district, and the third is a report on geochemical experiments, with a section on the occurrence of the orebodies. The last two are by John Cooper, of the United States Geological Survey, who has done much detailed work in the area. Stratigraphy The rocks of the mineralized area are Paleozoic sediments ranging in age from Cambrian to Penn-sylvanian. Several disconformities are present in the stratigraphic column, the most important one being between the Cambrian Abrigo formation and the Devonian Martin formation. There are no angular unconformities. Within the district, the Paleozoic sediments lie in a fairly uniform monocline, striking northwest and dipping 30" to 50" northeast. This local monocline is part of a domal struc-ture centered in the Little Dragoon mountains to the southwest. The Texas Canyon stock, a quartz monzonite body intruded probably during the Laramide revolution, lies south of the mineralized area (Ref. 2, p. 33). The Paleozoic rocks dip away from the stock, and on the surface are separated from it by at least 1500 ft of Pre-Cambrian rocks. The outcrop pattern of the northeastern edge of the stock suggests that it may dip gently northeastward, passing below the mineralized area at moderate depth. No quartz monzonite has been found in mine workings or diamond drill holes, which reach to depths of 1000 ft. The only igneous rock found in the mineralized area is a lamprophyre dike cutting the Naco limestone in and near workings of the Peabody mine. With the exception of the lowermost beds—the Bolsa quartzite and the shaly lower member of the Abrigo formation—the Paleozoic sediments are predominantly carbonate rocks, Fig. 1. The middle member of the Abrigo formation, which contains the principal ore-bearing beds, is limestone, with thin shale partings throughout most of its 250-ft thick-ness. Near the top of this member is a sandy bed some 25 ft thick. The upper member of the Abrigo formation and the lower half of the overlying Devonian Martin formation are dolomitic, with num-

Jan 1, 1954

By R-H Yoon

The thin film pressure balance (TFPB) technique was used to measure the kinetics of thinning of single foam films and disjoining pressures in the presence of sodium dodecyl sulfate (SDS) and electrolyte (NaCl). The results were analysed in view of the Reynolds equation to determine the role of surface forces in film thinning. It was found that film thinning is controlled by surface forces at thicknesses below approximately 200 nm. It was also found that hydrophobic force plays an important role particularly at low SDS and NaCl concentrations. The values of the hydrophobic force constant (K232) estimated from the film thinning experiments were used to predict the disjoining pressure isotherm using the extended DLVO theory, which were found to be in excellent agreement with experiment. The TFPB technique was also used to measure the equilibrium thicknesses (He) of the foam films stabilised by a non-ionic surfactant, n-octanol, in the presence of NaCl. At a given ionic strength, He increased noticeably with increasing octanol concentration at very low concentrations. This observation suggests that hydrophobic force is at its maximum level in the absence of surfactant and decreases with increasing surfactant concentration. The results obtained with the single foam films were used to explain the stability of the three-dimensional foams.

Jan 1, 2005

By R. M. G. Machunter

The presence of ultra-fine particles affects the separation performance of wet gravity separation equipment. Several studies have been undertaken to establish the maximum level of these particulates that can be tolerated by spiral separators and it has been found that unless the ultra-fine material is effectively processed, relatively low proportions in the ROM material combined with high feed rates can result in degradation in plant performance and/or excessive water consumption. The maximum level of particulate material in the process water has been determined by examination of separation performance of spiral separators under varying slime loading. This work has been conducted utilizing various feed sources and a robust ‘rule-of-thumb’ has been derived.

Jan 1, 2005

By Paul L. Michael

This report presents a discussion of perforance parameters for electronic or active hearing protectors that will meet the needs of underground coal miners. This information is incorporated into a proposed set of specifications that can be used to judge the suitability of a particular electronic hearing protector for the coal mine application. Acoustic and electrical tests were performed on a developmental model of an electronic hearing protector built by the U. S. Bureau of Mines. This model showed only a slight reduction in speech intelligibility which was traced to poorly matched components and in particular to the transducers. Tests of alternative components showed the Knowles BL-1671 microphone to be suitable for this application because of its performance and extremely small size. The Roan-well H-143/AIC earphone was found to have a good frequency response but has the disadvantage of being rather bulky which causes a slight degradation of a low frequency attenuation of the hearing protector. A satisfactory installation of these components in a hearing protector muff was demonstrated and tested. Results of tests of several methods of controlling the sound level under the hearing protector muff showed that a simple diode clipper circuit can be used with only a negligible loss in speech intelligibility for normal-hearing listeners. A commercially available active hearing protector, the British-built ACOS A-9000/2 was examined. This hearing protector provides sound level limiting through a saturating amplifier. Preliminary tests have shown that the performance characteristics of this commercial unit meet many of the proposed specifications so further testing and evaluation should be performed to determine its suitability for use 1n underground coal mines. The recommended test of intelligibility for electronic hearing protectors and other communication systems as used in a coal mine setting is the Modified Rhyme Test (MRT) developed by House et al. in 1965. The suitability and method of administering this test are discussed.

Jan 1, 1976

By C. A. Rawlins

INTRODUCTION Radcont is a program designed by the author of this paper for the industry to use as an instrument for radiation contamination evaluation and ventilation planning system. Radiation in mines are associated with the mining of gold and gold bearing minerals, as uranium and thorium is incorporated in the mining of these minerals. Radiation contamination in South African mines is not a new concept as it was investigated by the Chamber of Mines in the early 1960's and found not to be hazardous at the time. Since some of our mines export scrap metal to customers abroad, it came to light (1991) that some of the scrap metal was radioactive. The authority that oversees the nuclear aspects in South Africa is the Council for Nuclear Safety (CNS). They investigated these matters and found that the mines needed further information regarding radioactive material and the handling of these contaminated materials. As the various mines were licensed (with various conditions incorporated) thereafter, the mines had to do their own investigations as to what extent their properties (Surface and underground) were radioactively contaminated. Some mines were found to be highly contaminated over the years of operation and controlling conditions were installed and measures installed to reduce the contamination levels. One of the conditions when issuing a licence by the Council for Nuclear Safety (CNS), is that a screening survey be carried out to determine the radiation exposure levels and corrective action to be taken if necessary. These surveys must be done by a person trained in the required procedures for such a survey. The person must also measure the risk correctly and assess the results properly. In such a survey, the internal and external exposure levels must be determined to assess the total exposure of persons working in those conditions and take appropriate action if necessary. When doing such a survey, hundreds and more likely, thou- sands of data points are recorded. In order to assess the data recorded, various integrated and difficult calculations need to be made, and takes up enormous amounts of time. (This excludes the interpretation of the results ) The following explanation of the program shows the different parts of such a survey assessment calculations to be done. The paper details the program layout and the different sub- sections within the primary program. It must be stated that the program, as with any other program, is as accurate as the data inserted into the data base. The program and details thereof are given under the following headings: 1. TOTAL EFFECTIVE DOSAGE WITH REGARDS TO: • GME required gravimetric results obtained (mg/m3) • Thick layer or total contamination measured (Bq/m2) • Dry condition surveys with dust loads taken as a Standard l0mg/m3 • Wet conditions survey with dust loads taken as l mg/m3 • Airborne long lived alpha and beta activities as determined by analysis in Bg/m3 • LTD (Thermoluminescent Dosimeter). Results as obtained from the SABS (South African Buro of Standards) are recorded in this section for each month of the year for each individual worker. An average dose is then determined at the end of the year. • Bucket measurements as recorded. • Smear samples (Loose contamination). As determined by Electra or by analysis • Occupational factors for Metallurgical and Engineering occupations in and around the Metallurgical facilities of your mine. • All underground dosage determination and calculations. (Radon and Thoron) 2. INFORMATION REQUIRED WHEN PROGRAM IS INITIALISED: As the program is started, it opens up on the contents page. Here there are various options to choose from, but one is cautioned as a beginner in operating the program, not to perform any tasks before carefully reading these instructions. Firstly, one must go to the 'Information required" pushbutton. Press this button. The information required page is shown where the cursor can be moved to the block where one can enter the specific mines name. To enter a mines name, put the cursor in the block provided and just insert the mines name with the normal keyboard keys and press the enter button on the computer keyboard. To enter the other information required such as Alpha and Beta instrument efficiency, ALI (Annual limit of intake) and probe area, one can either press the 'Data required" button for a dialog box information or enter it manually by just putting the cursor in the block provided and entering as did above. In order to insert all the required information for the pro- gram to calculate the information required, one must proceed further by entering the area names surveyed in the spaces provided. There are 20 spaces to enter 20 different areas surveyed. One must further also provide the amount of days worked in each area (i.8. 250) in the block provided. The de- fault is 250 days. There are also standard information given in the information data page such as breathing rate (1,2 m31h), 8 hours worked per day, 5 days per week and 50 weeks per

Jan 1, 1997

By J. C. Bierlein, R. A. Dodd

Endurance strengths at 10' cycles, fatigue-hardening rates, and endurance strength/0.2 pct proof stress ratios have been determined jbr a range of Cu(Ni), Cu(Si), and S.R.0. Cu(Au) solid solutions. Some douht is cast on simple cross slip models of fatigue hardening in view of opposite composition dependencies of hardening displayed by Cu(Si) and Cu(Au). The temperature dependencies of hardening also are the opposite of predictions made on the basis of a cross slip model. A correlation apparently exists between the fatigue strength/0.2 Pc~ proof s1.re.s~ ratios and rates of fatigue hardening. An increase in PS/PS due to alloying or temperature change is accompanied by a decrease in hardening rate, and vice versa. In recent years there has been much interest in the determination of the dislocation structure of fatigued metals and alloys. The accumulated evidence, e.g., Refs. 1 to 5, suggests that the structure may be dependent on the stacking fault energy, 7, of the fatigued metal in the same way that fatigue hardening rates have also been shown to apparently depend on u .6' 7 The above research followed the various earlier theories relating crack nucleation to ease of cross slip, e.g., Refs. 8 to 131 so "ggesting that y may indeed be the parameter of principal significance in all facets of the fatigue process. However, comparatively little attention has been paid to correlating engineering fatigue data with observations of the above type. Certainly, it would be useful if potential engineering fatigue performance could be assessed from a knowledge of easily determined alloy properties, and the present research originated from this standpoint. TO investigate the widest Possible range of 7 would require the use of two solvent bases, e.g., aluminum and copper, but a reasonable coverage can be provided by copper-based solutions alone. Therefore, it was decided to work with Cu(Ni) and Cu(Si) solid solutions, the approximate stackillg fault energies of which are given in Table I. The y range extends from low, Cu(7.5 at- Pet Si), to moderately high in Cu(2-5 at. ~ct ~i) and two of the Cu(Ni) alloys. The values listed in Table I should be regarded as qualitative only, being derived as follows. Dillamore and smallman14 quote a value of 85 i 30 erg.cm-2 for the stacking fault energy of pure copper, based on an earlier value due to Howie and swannl5 corrected by Brown's formula.'' Since the ratios (alloy)h(pure copper) have been reported17,18 for Cu(Ni) alloys containing up to 30 pct Ni, approximate ) values for these alloys can be computed, and a rough estimate of 7 for Cu(50 at. pct Ni) obtained by extrapolation. The relatively low y value obtained in this way for Cu(50 at. pct Ni) coincides with the observation of Nakajima19 that the stacking fault probability is a maximum at this composition. Likewise, the y values for the three ~u(~i) alloys are estimates based on values given by Swann and Nuttingo corrected on the basis Of Brown's estimate that the true 7 values are probably 2.3 times greater than those originally computed. In addition to the above alloys it was decided to investigate short-range ordered (s.R.O.) CU(AU) alloys containing up to 25 at. pct Au. This last alloy has been shown to have a well-defined planar arrangement of dislocations when deformed,21,22 probably due to cross slip being restricted by the S.R.O. Engineering fatigue data was to be represented by the determination of endurance strengths, and these were to be correlated with fatigue hardening and mechanical property data. EXPERIMENTAL I, order to study the desired properties and property changes, the following alloys were prepared: Cu(2.5 at. pct Si), Cu(5.0 at. pct Si), Cu(7.5 at. pct Si), Cu(5.0 at. pct Ni), Cu(25.0 at. pct Nil, Cu(50.0 at. pct Ni), Cu(5.0 at. pct AU), Cu(15.0 at. pct AU), Cu(25.0 at. pct AU). The copper and gold were zone-refined, while the silicon was semiconductor grade. The nickel was of 99.95 p,t. purity.* All alloys were induction-melted in a *Kindly supplied by the International Nickel co. helium atmosphere, appropriate precautions being taken to avoid segregation in the Cu-Au series. Rod stock was obtained by rolling and swag,ng. A few Bridgman single crystals were grown for fatigue-hardening studies, but most material was machined into polycrystalline fatigue speciments of the design shown in Fig. 1, and into polycrystalline tensile and fatigue-hardening specimens of simple cylindrical design. All specimens except Cu(Au) were annealed; the latter were quenched from above T, to produce short-range order. A few of the quenched alloys were examined for long-range order by step-scanning over

Jan 1, 1969

The mining industry continues to experience a skills shortage and this is having an impact on the ability of mining companies to operate sustainably. Apart from a few exceptions, there is a dearth of geologists, mining engineers, metallurgists as well as environmental scientists and other professionals in the global mining industry. This relates to both quantity and quality. It makes good business sense for mining companies to employ local professionals rather than expensive expatriate staff. In some cases a mining company could employ more than 10 local mining engineers for the cost of one expatriate. However, in many countries local professionals are not always equipped professionally to work on mine sites. The result is that many companies are not operated optimally due to human resources gaps. In some cases, particularly in key areas such as mine planning, this threatens the sustainability of the operation or at the very least results in sub-optimal resource utilisation. This paper briefly presents some of the issues and strategies being implemented and that might be implemented to maintain a sustainable supply of quality minerals graduates to the industry in 2011 and beyond.

Jan 1, 2011

By S M. Aminossadati, R Bagherpour, F Hasheminasab

Mine ventilation is an essential part of underground mining operations used to provide fresh and cool air, as well as to dilute and remove contaminants from the work environment. This paper presents an overview of the ventilation and gas management systems in one of the underground coalmines in Iran: Parvadeh_1 mine. The mine is located in the Tabas coalfield in the South Khorasan province. It is the only fully mechanised mine in Iran utilising the longwall retreat technique. The mine produces 1.1 to 1.3 Mt of coking coal annually. The mine ventilation system currently utilises two 630 kW exhaust surface fans. The gas management system includes surface to in seam (SIS) predrainage boreholes. The underground mine is equipped with an underground gas reticulation pipeline that is connected to a surface plant for the production of methane gas. This study shows that the ventilation and gas management systems of the Parvadeh_1 mine are in line with the standards of Australian underground mines.CITATION:Hasheminasab, F, Aminossadati, S M and Bagherpour, R, 2017. An overview of ventilation and gas management systems in an underground coalmine in Iran, in Proceedings Australian Mine Vent Conference 2017, pp 41–46 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By Charlie Adcock, Rob Farnfield, Andy Wetherelt

The ISEE Blasters Handbook gives guidance on the level of air overpressure likely to cause occasional window breakage (151dB) and general window breakage (171dB). A long-term safe level of 140dB is also suggested. This guidance is widely used by demolition and other contractors to assess damage zones in the region of explosive applications employing unconfined charges. Other reference material gives more detailed guidance relating to window area, aspect ratio and glass thickness. Despite the guidance given in these references, complaints by members of the public regarding window breakage continue to be received by explosives engineers from air overpressure levels well below the longterm safe limit. Such complaints are not limited to the use of unconfined charges but can even be generated from the highly confined use of explosives in quarry blasting. This paper describes a series of experiments with explosive charges fired in unconfined conditions close to various window configurations. The aim of the work was to test the existing guidance levels and to extend the knowledge base in this area. Topics covered include the role of differential pressure across windows in the walls of an enclosed space such as a room.

Jan 1, 2006

By G. A. Zeito

Detailed visua1 examination of outcrops was used to ob-tain data on the lateral extent of shale breaks. Thirty vertical exposures belonging to maritie, deltaic and channel depositiorral environrrrents were exatmind, surveyed and photographed. The dimensions of the outcrops ranged from 356- to 8,240-ft long and 25- to 265-ft thick. Shale breaks were found to extend laterally for significant distances. and in some sands terminates by joining other break v much more frequently than by disappearance. Consequently with regard to flaw, a gross sand consisted of both continuous and discontinuous subunits. The degree of continuity of shale breaks as well as the occurrence and spatial distribution of discontinuities were different for the three depositional environments. Statistical eva1uations were performed to determine the confidence level with which estimates derived from outcrops can be applied to reservoir sands. Results of these evaluations revealed that: (I) the lateral continuity of shale breaks in marine. sands is si~nificatit, and the estimates of lateral extent can he applied to reservoir sands with a high degree of confidence (80 to 99 per cent of the shale breaks continued more than 500 ft, with a confidence of 86 per cent); and (2) the tendency for adjacent shale breaks to converge upon each other over small distances in deltaic and channel sands is highly significant (62 to 70 per cent of the shale breaks converged in less than 250 ft, with a confidence of 50 per cent), hut the probable magnitude of the resulting sand discontinuities cannot yet he predicted with adequate confidence. INTRODUCTION Almost all of the efforts devoted to characterization of the variable nature of reservoir sands have been focussed on permeability variations. Among the widely used concepts that have emerged from these efforts are those of stratified permeabilities, random permeabilities, and communicating and noncommunicating layers of different permeabilities. This study is concerned with the presence of interbedded shales and silt laminations. These features are impermeable or only slightly permeable to flow. Therefore, knowledge of the extent to which they continue laterally and the manner in which they terminate within the bodies of gross sands is important for proper description of reservoir flow. Initial field observations made on outcrops revealed that shale breaks and the relatively thinner silt laminae have impressive lateral continuity. They appeared to divide sand sections into separate individual sand layers. Although most of the layers were continuous across the total lengths of the outcrops, some were discontinuous because the- bounding shale breaks converged. Furthermore, the discontinuous layers appeared more prevalent in channel and deltaic sands than in marine sands. Based on these initial findings, a detailed investigation was carried out to determine, quantitatively: (1) the degree of continuity of shale breaks in marine. deltaic and channel sands; and (2) the frequency and spatial distribution of discontinuities in the three environments. PROCEDURE The procedure used to obtain field data from outcrops included visual examination, surveying and photographing each outcrop. The photographs were examined carefully and important outcrop features were traced, measured and recorded. The selection of outcrops for this study was made on the basis that each outcrop should be exposed clearly to permit detailed visual examination of vertical lithology. and it should also be sufficiently long (over 200 ft) to provide useful data on the lateral continuity of lithology. Identification of the depositional environment for each outcrop was made on the basis of bedding characteristics, vertical sequence of lithology and the presence of indicative sedimentary features. Whenever possible, hand specimens of associated shales were collected to determine depositional origin. Almost one-half of the outcrops used in this study required environmental identification; the remainder had already been identified by previous investigators. Several photographs of each outcrop were usually required to cover the entire length of the outcrop. These photographs were taken from one station or several, depending on the terrain, size of the outcrop and distance to the outcrop. A Hasselblad camera, with a standard 80-mm lens and a 250-mm telephoto lens, was used. The telephoto lens permitted photographing outcrops as far as two miles away. Slow-speed films were used. either Panatomic-X or Plus-X. The final operation conducted in the field was that of surveying the outcrops. The distance of an outcrop from a point of observation was determined by a triangulation method using the plane table. The measured distance was then combined with the angle of view of the camera lens to establish a scale to be used on the photographs. Films were processed using standard processing techniques and 4.5X enlargements made. The enlargements of each outcrop were butted together to form a single panorama. Slides were also prepared on several outcrops; these were used whenever greater magnification (wall projection) was required to bring out maximum lithologic detail. The shale breaks and bedding planes in each outcrop were traced on transparent acetate film superimposed on

Jan 1, 1966

The Dynamics and Thermodynamics of Absorbing Lithium of Ion Sieve Preparing Pollymetallic Nodules

Sep 13, 2010

By D K. Weatherley, G R. Ballantyne, S Ali, M Yahyaei, M S. Powell

This paper explores development of a novel ore characterisation method for the precise measurement of practical minimum comminution energy. A monolayer of particles with a narrow size distribution is broken using a precision rolls crusher (PRC); an ore characterisation device developed to overcome the shortcomings of conventional tests. For energy measurement, PRC uses two shaftmounted rotary torque transducers. These transducers acquire precise torque and angular speed data in response to the load applied to the rotating shafts during breakage events, which is converted into energy. The test progressively crushes feed particles down to final product size in many controlled breakage stages. The generation of fines in each breakage stage is then plotted as a function of input energy. The inverse of the gradient of this plot provides the size specific energy (SSE) in kWh/t of material generated below a predefined marker size; -75 μm in this case. The PRC has potential to evolve as a geometallurgical ore characterisation test—it is simple, fast, requires small sample mass (200–300 g), covers a wide feed particle size range (10 mm to 115 µm), and provides ideal SSE measurements that can be used for the calibration of on-site production equipment.

Aug 24, 2022

By P. Dupeuble

Diaphragm walls, owing to their method of construction are discontinuous structures. A new technology for the construction of joints between panels has been developed. This new process allows for the construction of diaphragm walls with mechanical and watertight continuity.

Jan 1, 2010