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By Nicholas J. Grant, Italo S. Servi

Extensive data of minimum creep rates and rupture times for high purity and commercial aluminum confirm the existence of a transition range from the low temperature-type to the high temperature-type behavior. The data are analyzed in line with the suggested theories of deformation of metals. CONSIDERABLY more work has been done on the rupture and creep behavior of commercial alloys than on the less complex, high purity metals. As a result, certain fundamental behaviors are overlooked. One of the lesser known variables affecting the high temperature behavior of metals is the impurity content (or alloy content). Impurities are known to affect strongly the recrystallization temperature, electrical resistivity, and other properties of metals, but the effect on creep and other high temperature mechanical properties has been determined for very few materials. In view of these facts aluminum appears to be a fairly ideal metal, since it is available in a wide range of purity contents from 99.995+ down through the 2s (99.0 + Al) and 3s (1.2 Mn) grades in small steps. It is highly resistant to oxidation and other surface instabilities, leaving recrystallization and grain growth as virtually the only instabilities. Control of grain size is also well standardized. Limited data on the creep of aluminum have been obtained by Dushman et a1.l for high purity aluminum; by Sherby2 on 2s aluminum of variable grain size; and by Dorn and Tietz³ on cold-worked 3s aluminum. Experimental Procedure The apparatus consisted of a constant stress, creep testing unit similar to the type described by Hop-kin.' The specimens were held at temperature for 30 min before loading. The loading time was less than 2 min. Factors affecting the accuracy of the data were: 1-—the temperature gradient and control, ± 3°F; 2-the stress determinations, ± 1.5 pct; and 3—elongation measurements (1 in. gage), ? 0.001 in. Three grades of aluminum were tested: 1— high purity (99.995 pct Al), 2—2s (99.3 pct Al), and 3—3s (98.2 pct Al). The spectrographic analyses of these materials are reported in Table I. The specimens were annealed then electropolished in a perchloric-acetic mixture before testing. Data on heat treatments and grain size obtained appear in Table 11. The entire creep curve was determined for almost all of the tests. A few tests were interrupted after the beginning of the third stage of creep, and in these cases the rupture time was estimated. Experimental Results Constant stress creep-rupture testing gives a much longer, more accurately measurable second stage of creep than constant load testing. This behavior is in agreement with the results obtained by Andrade for lead (see Fig. 1). If the test is run to completion, the third stage of creep appears as soon as stress intensification occurs. In the case of specimens which fail in a ductile manner, the stress intensification begins when the sample starts "necking". This differs from the "high temperature brittle" specimens in which the stress intensification is caused by intercrystalline cracking. These specimens

Jan 1, 1952

By John Nagy

A study was made in the Bureau of Mines experimental coal mine of factors affecting gas ignition by a cutoff explosive charge. Experiments showed that, although gas could be ignited under some circumstances, the probability under normal mining conditions would be low. The use of permissible explosives, relatively short-delay intervals in firing adjacent holes, blasting to a 6-inch kerf, and reasonable care in the placement of the holes favor safe blasting and are current practice in mining. The experiments also showed that the weight of the charge is not a primary factor in the ignition of gas by a cutoff charge. The quenching action of a first charge on the igniting action of a second was verified in a supplementary study. Related experiments have shown that gas at the face may be ignited by a single charge of explosive when fired with a light coal burden. Permissible explosives were less hazardous under these conditions than nonpermissible explosives. The frequency of gas ignition in cutoff and single-charge experiments increased as the linear distance between the sheared face and the opposing mine rib increased.

Jan 1, 1960

By Fitzhugh T. Lee

Results from the first part of a two-part investigation of the stability of highwalls in open-pit coal mines in the Paleocene Fort Union Formation of the western Powder River Basin of Wyoming and Montana indicate that these highwalls are subject to time-dependent deformation. Field investigations and laboratory physical properties tests of coal and overburden rocks suggest that several factors influence highwall stability. Some of these factors are rebound of overconsolidated rocks, desiccation, water, orientation and spacing of fractures, and strength and deformation properties. Factors of safety for a typical highwall in the study area (calculated by the finite element method) may be less than 1.0 when open fractures are present and the highwall has degraded. Although it is concluded that most open-pit highwalls in the Fort Union Formation within the study area have adequate short-term stability, these highwalls do deteriorate and become progressively less stable. Because of this, postmining failures are common and stability conditions could become critical if mining were delayed and then resumed after a period of several months. The second part of the investigation will utilize field measurements of rock-mass properties and instrumentation of actively mined highwalls to obtain data for comparison with the results of the initial investigation. Because the height of highwalls will increase as the more shallow coal is exhausted, these data will also be used to predict the behavior of slopes higher than those presently found in the western Powder River Basin.

Jan 1, 1977

By Leonard L. Fischman

It is important to define "adequacy," and the most useful definition is a continuing availability of mineral materials under cost and other conditions which imply no significant burden on the achievement of otherwise attainable levels of consumption and well-being. For current decision making, it is sufficient to consider adequacy just to the end of the century, with some regard being given to then remaining mineral inventory. A comparison of cumulative demand projections to the year 2000 with already identified reserves ( economically recoverable amounts in known deposits) suggests little reason for concern with world adequacy of iron ore, aluminum, manganese, chromium or potash. Conservative estimates of "prospective" reserves (amounts producible at today's prices, but yet to be discovered) suggests that there are ample quantities of virtually all other mineral resources as well. A probable exception is oil and gas, of which there may be scant amounts remaining after the turn of the century. However, there is an evident sufficiency of substitute forms of energy, though it is difficult to see just where developing technology will take us. The critical questions have to do with the increasing dependence of the industrialized countries on external sources of supply , coupled with a new international politic s which complicates the problem of insuring timely development of, and access to, remaining deposits. In this context, Canada, a still mineral-rich nation, is in one of the more favorable positions.

Jan 1, 1977

CONTENTSIntroductionGeneral GeologyCoral Reef-Volcanic Set'iesRock TypesMicaceous Sandstone and MudstoneLimestoneVolcanic RocksChertsDepositionDiatremesEarth MovementsRelation of Ore Bodies to StructureINTRODUCTIONThe author encountered the problems discussed in this paper in 1947 while surveying the mining centres of Mungana and Redcap for Broken Hill South Ltd. After his resignation from that company he made a semi-regional survey to investigate the regional problems raised by the preliminary study. Broken Hill South Ltd. continued its studies on the known ore bodies while the author's investigation was going on, and he is indebted to the staff of this company for assistance during his field work.The area mapped is part of a larger area mapped in reconnaissance by the Aerial, Geological and Geophysical Survey of Northern Australia by a party headed by Dr. H. I. Jensen...

Jan 1, 1952

"A commercially available through-the-earth (TTE) communications system was evaluated at an underground coal mine in eastern Kentucky. This field study was conducted as part of a larger multisite evaluation of available TTE systems. The mine detailed in this paper was idled at the time of the study, which provided the nearest practical representation of a postevent mine shutdown environment. For this study, surface-to-underground and undergroundto- surface communications were tested. Standard deployments of the TTE system using the manufacturer’s recommended procedures were able to achieve clear communications between underground and surface locations. Other arrangements of the units yielded mixed results. Future experimentation is planned to further examine the phenomena observed at this mine IntroductionThe ability to establish effective communication between surface and underground personnel after a mine event is essential for both evacuation and rescue efforts. Current wireless underground communication technologies are reliant on intermediary physical infrastructure, such as antennas and repeaters, to enable underground communications. As such, communications are easily disabled during a mine event because of the inherent vulnerabilities to physical damage (Damiano, 2012; National Academy of Engineers, 1970; Yenchek et al., 2011). A true emergency communications system would function regardless of a mine’s physical state. Through-the-earth (TTE) wireless communication technology only requires the use of a single transmitter and a single receiver to achieve point-to-point communication through solid strata. With this capability, TTE systems have the potential to serve as a true emergency communications platform."

Apr 1, 2016

By Fred Delabbio

There are presently several issues that the mining industry is facing, such as underground air quality, deep mining and green house gas emissions, which could be addressed by the application of alternate energies. Several aspects must be considered by the industry in any drive to introduce new technologies within the context of a producing underground mine. This article presents several operational and support aspects that will evaluate the relevance of alternate energies, with emphasis on hydrogen power systems: operational drivers, commercial supply of technology, site supply system requirements, health and safety, capital and operating costs, mine production, corporate philosophy, and role of government. It is concluded that introduction of alternate energy technology requires a step-wise progression: Applicability to the industry, proof of concept testing, development of generic infrastructure, power systems and regulations, whole system studies and detailed studies of cost and risk versus benefits. The current initiative to apply fuel cells is at the proof of concept stage, entering the generic infrastructure stage.

May 1, 2007

By Richard D. Grove

The on-stream analysis of phosphorus and silica has not been possible by XRF techniques and only recently has some success been indicated with quantitative XRD for P. Yet there has been a recognized need for an on-stream analysis of P and acid insoluble to permit the automatic control of phosphate rock flotation plants which produce some 30-40 million tons of concentrate each year in the southeastern U.S. IMC Fertilizer, Inc., the largest U.S. phosphate rock producer, embarked on a program to develop such an on-stream analysis capability several years ago. Following many months of lab and prototype development, the first commercial installations started in December 1986 and now have completed some 400,000 analyses with surprising accuracy, precision and reliability. The use of these devices in the improved control of the phosphate flotation plant is currently receiving some very serious attention at IMC.

Jan 1, 1989

By M. Z. Sukiennik

A static method for vapor pressure measurement up to 1450 K and above 1 hPa is presented. The method is designed for equilibrium and kinetic studies of metallic systems, including those with a chemical reaction. Application examples are given for determination of activities in condensed phases, and heterogeneous reaction rates and equilibrium constants.

Jan 1, 1993

An AFM has been applied to study in situ the adsorption of oleic acid on fluorite in aqueous solutions. The AFM images show that fluorite surface becomes smoother with the adsorption of 7 × 10-5 M oleic acid solution at pH 9. Force measurement shows that fluorite is strongly positively charged in water at pH 6, suggesting a neglectable surface carbonation of fluorite. The adsorption of oleic acid at pH 9 renders fluorite more and more negatively charged. The surface morphology change of fluorite as shown by the AFM images suggests that oleic acid chemisorbs on fluorite at pH 9. Increasing temperature can help increase the adsorption of oleic acid on fluorite. It may also improve the lateral polymerization of unsaturated oleic acid on fluorite as suggested by the smoother mineral surface in oleic acid solutions at an elevated temperature.

Feb 23, 2014

By George H. C. Norman

A NUMBER of methods have been developed for the determination of the dust concentration in air, some of which have been reported as very efficient and for research may be more satisfactory than the method about to be described. In practical mine use, however, the accurate research equipment is unwieldy and requires a high degree of technical skill to manipulate it. Also, it gives less general practical information to the operator in the same length of time than the method described here. Moreover, it is doubtful whether at the present stage of affairs the results obtained from the precise methods have any more practical significance than those obtained with simpler and more portable apparatus, which can rapidly give a sufficiently reliable indication of the relative dust hazard. HISTORY OF DUST DETERMINATION IN ONTARIO The first record of mine-dust determination in Ontario is given in an article by Dr. J. H. Elliott,' in which he records a few dust counts made with the Palmer spray apparatus. There were insufficient data from which to draw any definite conclusions or reasonably compare with present-day counts using the konimeter. The first konimeter dust sampling was started in the Porcupine district in 1926, using light-field counting without adhesive and with no sample treatment before counting. A method of semidark-field counting was used from about 1928 to 1931 and dark-field illumination was adopted permanently about December 1931. The konimeter has been continued as the principal means of dust sampling in the mines of Ontario, where South African practice has been adopted because in South Africa most careful study has been given the problem of silicosis, and very complete records of work done there are

Jan 1, 1937

By J-P Franzidis, E V. Manl, K Runge

Over recent years a number of techniques have been developed as part of the Australian Minerals Industries Research Association (AMIRA) P9 project to represent mathematically or measure directly subprocesses occurring in flotation cells. These include the determination of a:machine parameter (bubble surface area flux, Sb); froth parameter (froth recovery, Rf); entrainment and drainage parameters; and ore floatability parameter (Pi). A cost-effective methodology was developed for using these techniques to derive models of flotation circuits. This methodology was applied to derive a model of the flotation circuit at the Western Mining Corporation (WMC) Ltd Mt Keith Nickel Concentrator. The model was used to simulate a number of minor circuit flowsheet changes, the results of which are discussed in this paper. One year later, a second study of this plant was conducted. In this second study, data were collected while operating the plant in the flowsheet configurations that were simulated from the model developed from the first study. The results obtained from the second study showed reasonable agreement with the trends predicted from the first study model; discrepancies can be explained in terms of the model assumptions. This suggests that this simple circuit modelling methodology can be useful in assisting plant engineers to optimise flotation circuits.

Jan 1, 2000

By David Chadwick, Paul Marsden, Chris Hughes, Mathias Delapille

"Following damage caused by the 2011 Christchurch earthquakes, the NZ$127.5million Christchurch Town Hall Restoration project is due for completion in 2018. The building is undergoing extensive repairs and a strengthening regime to meet New Zealand’s New Building Standard. One major aspect of the project is the stabilisation of the soil directly beneath the building using interconnected jetgrouting columns installed a cellular configuration, the purpose of this being to decrease the likelihood and severity of foundation movements caused by earthquake-induced soil liquefaction and lateral spreading. The soils encountered on the site ranged from cobbles and gravels through to sandy silts with a significant quantity of timber and rootlets. This wide variation of soil types presented a number of challenges with regard to effective and consistent treatment by jet grouting. The paper presents an overview of the quality assurance practices and also the testing regime adopted on this project.INTRODUCTIONMost of the deformation experienced by the Christchurch Town Hall structure over the course of the Canterbury earthquakes was caused by movement of the underlying ground. Two primary mechanisms of ground deformation were observed:- Liquefaction of the soils underlying the building foundation- Lateral spread of surface soils towards the free face at the river edge which runs 20 metres from the building. This mechanism also resulted in additional vertical settlement of the building foundations.The overall foundation design philosophy adopted by the project team for the Christchurch Town Hall Conservation Project has been to improve the ground directly beneath the structure to mitigate against these two mechanisms of ground movement. Additionally, a robust raft slab is proposed to distribute the foundation loading more evenly and increase the ability of the structure to resist lateral stretch of the underlying ground.The ground improvement system proposed by the Client’s geotechnical consultants, Tonkin &Taylor, comprised a cellular arrangement of interlocking jet grout columns, this arrangement would effectively encapsulate the soil within the cells preventing lateral spread.In total 1,097 interlocking jet grout columns, extending over the entire floor plan of the structure, were required to satisfy the design requirements."

Jan 1, 1900

By Lucien Eaton

This paper describing the mining practices at Mine No. 1, Menominee Range, Mich., is one of a. series being prepared by the Bureau of Mines on mining practices, methods, and costs in the various mining districts of the United States. It is felt that the publication of this information will be of interest and value to the mining industry at large and especially to operators whose mining conditions are similar to those described. ACKNOWLEDGMENTS The author is indebted to the superintendent, engineer, and mining captain of Mine No. 1 for much of the information presented.

Jan 1, 1929

By Liaqat Ali, Robert Chapman, Asghar Ali, Mohammad Tahir Shah, Seema AnjumKhattak, Mohammad Farhan

Alluvial gold is abundant in the Quaternary deposits of the Kabul and Indus rivers in District Nowshera, Khyber Pakhtunkhwa, Pakistan. Understanding the provenance of alluvial gold using morphology and elemental composition could be helpful in developing an exploration strategy of regional benefit. Detailed morphological studies of gold grains revealed high flatness index values which are indicative of a distal source. Compositional studies of 58 gold grains using SEM and EMPA showed broadly similar Ag ranges (1– 15 wt%) for each sample and occasional Cu values in individual gold particles to 0.4 wt%.Whilst the Ag profile is not diagnostic, the Cu values are compatible with derivation from either porphyry systems or ultrabasic rocks. The complex geology of the drainage catchments could host gold mineralization of other styles, but larger sample suites would be required to refine the current interpretation to establish whether particles which are simple Au-Ag alloys could be derived fromorogenic or epithermal sources. This scoping study has demonstrated that the compositional and morphological studies of gold grains are useful in providing information regarding the nature and location of the source of placer gold in areas where there is limited information on the nature and location of in situ mineralization.

Oct 6, 2020

By E. E. Jones

The lignites of Arkansas, Louisiana and Texas are typically described as muitiseam deposits which contain quantities of day and sand in thin lenses or in admixture with the fuel itself. These materials are often included in the run-of-mine fuel and can have very adverse effects in the end use. Since May of 1982 the Dow Chemical Co. has operated a pilot plant for the beneficiation of lignites. This facility has successfully removed sand, clays and petrified wood from the lignite producing a fuel comparable to or better than the selectively harvested run-of-mine materials. The design, operation and results from this plant were presented by J. H. Everitt at the 1984 Coal Technology Conference.

Jan 1, 1986

By G. A. Gamble

Fans used to ventilate subway, passenger rail and vehicular tunnels are similar to the fans used to ventilate underground mines. However, tunnel ventilation fan systems are typically designed to meet NFPA 130 or 502 standards, while mine ventilation fan systems must comply with the appropriate federal mine safety regulations. As a result, fan operation requirements and performance criteria, as well as typical fan and duct configurations differ significantly for tunnel and mine ventilation applications. Variations in environmental conditions in tunnels as compared to mines also result in differences in fan performance and material specifications. The need to enclose tunnel fans within building structures creates space restrictions impacting fan size selection that are not commonly encountered in mine fan installations, resulting in different approaches to selecting fans for the two types of tunnels. This paper discusses the various similarities and differences in design considerations for tunnel and mine ventilation fans.

Jan 1, 2009

By S. Neven

The smelting of copper anode slimes, a material which contains mostly lead, silver, copper and selenium, has been practiced for many years with a view to recovering the silver and associated small amounts of gold. However, a theoretical understanding of the process has been lacking and this handicaps efforts to improve and intensify smelting operations. In the past few years work has been done in this area and this work will be reviewed in the paper. The underlying thermodynamics of the oxidation of silver-copper selenide mattes has been developed and used as a basis for the construction of a computational thermodynamics model which attempts to predict the composition of all condensed phases during the course of smelting. The model will be outlined and its successes in matching experimental data, as well as its current deficiencies, will be considered. Supporting work on the thermodynamics of silver solubility in slags, on activity-composition relationships in the Ag-Se system and work in progress on the oxidation state of copper in the slags will be reviewed. These projects are designed to provide further detailed data which will improve the robustness of the thermodynamic model.

Jan 1, 1999

By Y. Shiraishi, Y. Sakurai

A new method, the gliding cylinder method, was proposed as a wide range viscometer for the measurements of molten salts, slags, and glasses. The method consists of two coaxial cylinders, cylindrical bob and a vessel containing a liquid sample. There is a narrow gap between bob and vessel. When the vessel moves against the bob, the generated force on the bob consists of three types of resistance: (1) Stokes’s resistance on the bob, (2) a capillary flow resistance though an annular gap between vessel and bob, and (3) lubricating resistance in a gap. The last two can be calculated on a theoretical basis but the first cannot be estimated by a simple calculation since a wall effect did not calculate easily. However, it can be assumed that the generated force depends on both the viscosity of a liquid and velocity of the vessel. Thus, the relation between viscosity and a force at desired velocity of the vessel was measured using several standard reference materials including glycerol aqueous solutions and standard reference oils. The results depended on the magnitude of the gap between the bob and the vessel. For the wider gap, it was shown that the viscosity is a linear function of a gradient of force with respect to a vessel velocity. In contrast, if the gap is small, the viscosity depends on the gradient (of force with respect to velocity). This implies that the non-linear phenomena would occur in Stokes resistance. Though detailed analysis is in a further investigation, a calibration method can be applied to determine the viscosity by this method, because good correlation was obtained among these quantities. Viscosity of molten salts, such as NaNO3and ZnCl2was measured by this method as high temperature demonstration. Keywords: viscometer, viscosity, sphere pull-up method, fused salts, molten slags, glass melts

Jan 1, 2004

By E. G. Davis

The Bureau of Mines studied tailings samples from 11 large-scale western copper operations to determine the potential for recovery of rutile and other critical and strategic minerals. Up to 15 pounds per short ton (lb/st) Ti02 was found ion these samples; however, only 9 to 44 pct of the Ti02 was liberated rutile. For one sample, gravity preconcentra-tion, grinding, and flotation recovered 34 pct of the Ti02 in a 54.8-pct-Ti02 concentrate. Over 0.38 Ib/st W was found in some of the tailings sampleso Scheelite was identified as the major W mineral. Nine of the eleven samples contained about 0.02 to 0.18 Ib/st Co. Pyrite was the principal Co-bearing sulfide mineral, with Co contained in about one-fifth of the pyrite grains. Up to 30 pct of the Co was concentrated in a bulk sulfide flotation concentrate.

Jan 1, 1988