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By Melinda Bissinger, Frederic Berube

Environmental considerations are important in the aerospace industry. To that effect, several elements such as engine emission, noise and materials are identified by the industry and the society as requiring significant improvements for future and current products in order to be aligned with current expectations. In this context, the industry is addressing this opportunity by investing significantly in new engineering solutions that will meet greener targets. To this effect, the impact of material choice is significant and will make a difference in the forth coming solutions. Several opportunities to develop more efficient products, quieter aircrafts using materials and manufacturing processes that will be more respectful of environmental considerations exist. The presentation will cover those elements and provide an overview of the upcoming solutions.

Jan 1, 2010

By G. D. Hibbard

New regions of material property space can be accessed by combining microstructural design at the nm-scale with architectural design at the µm- or mm-scale. In the first case, large strength increases associated with grain size reduction to below 50 nm have driven extensive research efforts into the development of nanocrystalline materials [e.g. 1-3]. For many potential structural applications, however, the density of a nanocrystalline material is just as important as its strength. In fact, reducing the density is more important than increasing the strength for certain weight specific materials performance indices, and it is especially critical for applying structural nanomaterials in the aerospace and automotive sectors. We have developed a new type of structural nanomaterial wherein the effective density of the parent metal is reduced by more than an order of magnitude by incorporating an internal periodic cellular architecture of open space. In one example a low density cellular nanocrystalline material was created by electroforming nanocrystalline Ni around a rapid-prototyped acrylic photopolymer microtruss, Figure 1 [4]. Microtruss materials have periodic cellular architectures that are specifically designed to undergo stretching-dominated deformation as opposed to the bending-dominated deformation in conventional open cell metal foams [5,6]. This new cellular nanocrystalline hybrid material combined the structural efficiency of microtruss architectures with the ultra-high strength that can be achieved by grain size reduction to the nm-scale. Although it played a critical role as a cathode support during the initial stages of nanocrystalline electrodeposition, the polymer core did not contribute significantly to the inelastic buckling resistance of the composite metal/polymer struts and it may therefore be desirable to remove it post deposition by means of chemical dissolution or thermal decomposition [4]. Nanocrystalline electrodeposition can also be used to reinforce conventional cellular metals (Figure 2), creating new types of cellular composites such as metal/metal microtruss hybrids [7-10] and metal/metal foam hybrids [11,12]. For example, nanocrystalline Ni-Fe alloy sleeve thicknesses of up to 400 µm were used to reinforce an aluminum alloy microtruss that had been fabricated using a stretch-bend approach; the nanocrystalline sleeves had the effect of increasing the microtruss strength by up to a factor of twelve and the specific strength by a factor of three [8]. Alternatively, much thinner sleeves can be electroplated to produce structural coatings. In one example, a nanocrystalline Ni coating was designed to provide both corrosion protection and inelastic buckling resistance [10]. Because the ultra-high strength material was optimally located at the furthest distance from the neutral bending axis, only a thin coating of 50 µm was needed to double the inelastic buckling resistance of the 1.13 mm x 0.63 mm cross-section plain carbon steel struts [10]. Overall, the mechanical performance increase that can be obtained through electrodeposition depends on a complex interaction between the starting cellular architecture and the nanocrystalline sleeves.

Jan 1, 2010

By D. R. Tweeton

The U.S. Bureau of Mines, the University of Arizona, Sandia National Laboratories, and Zonge Engineering and Research Organization, Inc., conducted cooperative field tests of six electromagnetic (EM) geophysical methods to compare their effectiveness in locating a brine solution simulating in situ leach solution or a high-conductivity plume of contamination. The brine was approximately 160 m below the surface. The testsite was the University's San Xavier experimental mine near Tucson, AZ. Geo- physical surveys using surface and surface-borehole, time-domain electromagnetic (TEM) induction; surface controlled-source audiofrequency magnetotellurics (CSAMT); surface-borehole, frequency- domain electromagnetic (FEM) induction; crosshole FEM; and surface magnetic field ellipticity were conducted before and during brine injection. The surface TEM data showed a broad decrease in resistivity. CSAMT measurements with the conventional orientation did not detect the brine, but measurements with another orientation indicated some decrease in resistivity. The surface-borehole and crosshole methods located a known fracture and other fracture zones inferred from borehole induction logs. Surface magnetic field ellipticity data showed a broad decrease in resistivity at depth following brine injection.

Jan 1, 2010

By ISEE

Micrometer Crack Response to Vibration and Weather, by Prof. Charles H. Dowding of Northwestern University, adds to Prof. Dowding’s already important contributions to the industry with his “Construction Vibrations” books. This new book reports and interprets important data on crack response that are essential for differentiating the unseen effect of weather on structural cracking from the usually much smaller effect of vibration. In addition, the book contains detailed descriptions of data collection methodology.

Jan 1, 2010

By Henk van Muijen

From an interesting and intriguing scientific research topic, deep sea mining has altered into an interesting mining prospect over the last years. Ten years ago most of the focus was on geological investigations, searching for typical deep sea deposits and getting answers on where we can find them and how these deposits were formed. At this moment we know much more about the interesting deposit possibilities and with our quest for minerals, metals and other materials to feed global economic growth, answers as to the technical and economic feasibility to mine these deposits are sought. This is not a new phenomenon as we already witnessed such question late 1970?s and early 1980?s. Most of the focus was on mining manganese nodules and brines in the Red Sea driven by the report of the Club of Rome that predicted shortages in near future at that time. Development went different, but later in the 1990?s a rival of interest could be noticed for mining deep sea deposits.

Jan 1, 2010

By D. P. Desmond

The U.S. Bureau of Mines investigated leaching automobile catalysts with sodium cyanide (NaCN) solutions at high temperatures to recover platinum-group metals (PGM). The feed was virgin monolith rejects, used monolith, and used pellet catalysts. Leaching with a 5-pct NaCN solution for 1 h at 160° C dissolved over 97 pct of the PGM in the virgin monolith, over 85 pct of the PGM in the used monolith, and over 90 pct of the PGM in the used pellet catalyst. Over 99.8 pct of the dissolved PGM was recovered as a precipitate by heating the solution to 250° C for 1 h in an autoclave. The cyanide complexes were decomposed, and free cyanide was destroyed.

Jan 1, 2010

By Michael R. Yenchek

The U.S. Bureau of Mines investigated the operational characteristics of spliced portable power cables. This research had a dual purpose: (1) to determine the thermal and mechanical performance of repaired trailing cables and compare them with undamaged cables and (2) to gauge the impact of long-term, localized heating on the insulating and jacketing materials contained in cable splice kits accepted or approved by the Mine Safety and Health Administration. The ranges of splice joint resistance and tensile breaking strength were determined from laboratory measurements. The choice of crimping tools affected the strength of the splice under tension. Thermal profiles of energized spliced cables were constructed, which showed that spliced conductor joints operated 5 to 20°C hotter than the intact cable at rated currents. Accelerated life tests of thermally aged samples of splice kit insulation and jacket materials confirmed a deficiency in the thermal rating of the insulating tape. The recommendations in this report may be utilized to revise splice kit design, splice kit approval criteria, and trailing cable loading guidelines. Characterizing the thermal operating limits of spliced trailing cables may help to minimize the associated risks from explosions, fires, personnel burns, and shock.

Jan 1, 2010

As metal prices fluctuated over the years, so too have the fortunes of many of those mining in Canada?s Yukon province. With a rich mining history that dates back to the Klondike gold rush of 1896 to 1898 and continues to thrive today, Yukon has experienced several ?boom-and-bust? cycles. However, during the world?s most recent mining ?bust? Yukon has held strong and has re-mained one of the world?s hottest destinations for mineral exploration. In fact, the area even exceeded forecasts in 2009, more than doubling last year. And the near-future looks just as bright.

Jan 1, 2010

By L C. Taylor, H U. Lesiste

This is a preliminary study of the statistical variation of the pressures on a target above a buried explosion. The data were taken at various distances from the charge centerline for three heights of the target above the soil and one charge depth of burial. All tests were conducted in saturated sand. They show that peak pressures and times of peaks are neither repeatable from shot to shot nor rotationally symmetric within a single shot. The peak pressure and time of peak at each location can be represented by cumulative normal distributions. The paper describes the means and standard deviations of these distributions at eight distances from the charge center for each height of target. These are used to determine the change in standard deviation of the distribution with distance from the charge centerline and height of target. The effect of scale on the mean peak pressures and times of peaks and on their standard deviations at a single scaled distance from the centerline of the charge are explored using various charge weights.

Jan 1, 2010

By D. K. Steele

The domestic primary copper industry generates in excess of 600 million t of mining and mineral-processing waste annually. Most of the waste poses negligible environmental threat, but a small fraction, because of toxic or corrosive characteristics, may be subject to regulation under Subtitle C of the Resource Conservation and Recovery Act (RCRA) or other pertinent regulations. Among the wastes generated by various copper producers are flue dusts, slags, refinery-bleed solutions, and. acid-plant wastes. The U.S. Bureau of Mines (USBM) has researched methods to mitigate the environmental threat posed by copper-processing wastes while recovering valuable metals from these materials. Acid-leach processing of flue dusts has been demonstrated feasible along with sulfide treatment of liquid refinery wastes and acid-plant-bleed and gas-cleaning solutions to precipitate dissolved metals. In, addition, the feasibility of removing copper and molybdenum from slag, as well as stabilization of precipitated sulfide wastes by vitrification, have been investigated.

Jan 1, 2010

By David Leidel, James Stuart

The 50 ohm resistorized electric detonator is commonly used in the oilfield for initiation of wireline conveyed perforating guns and other downhole explosive tools. This type of electric detonator provides some degree of safety above that of the conventional one ohm electric detonator, since a higher current level is required to initiate the device. In order to obtain the necessary data to develop safe distance tables from RF sources for the 50 ohm electric detonator, laboratory tests were conducted to determine the detonator’s “no-fire” current, AC impedance, and its susceptibility to ESD. The results were surprising as two types of failure modes were observed. The “no-fire’ current levels determined from Langlie “One-Shot” Test Methods were determined for the devices tested providing values for the 0.999 probability “no-fire” power level at a 95% confidence level. This data will serve as the basis for sets of safe distance tables from RF sources that will appear in the forthcoming edition of the Institute of Makers of Explosives Safety Library Publication 20, “Safety Guide for the Prevention of Radio Frequency Radiation Hazards in the Use of Commercial Electric Detonators, (Blasting Caps)”.

Jan 1, 2010

By J. Hendry, K. Brady, J. Yorzyk

Drawing from the experience of nickel, copper, aluminum and mineral borates, this paper illustrates the business value that the mining, minerals and metals industry as a whole can gain from applying life cycle assessment (LCA) to products and operations. Through the use of case studies, the paper explores how companies and industry associations have used LCA to their advantage: from evaluating capital investments, meeting customer information needs, supporting new product applications, and developing credible marketing information on the environmental performance of their products. It also explores the dynamics of LCA adoption and integration within companies, and provides recommendations to further strengthen institutionalization of LCA.

Jan 1, 2010

By Brian Ulrich

The majority of individuals involved in the mining industry can appreciate and under-stand that mining is an activity that is necessary to satisfy the very basic needs of society, and to assist in accommodating our ever-changing world. As the expression goes, ?if it can?t be grown, it has to be mined.? And at this point in time, society has granted the mining industry the right to go about the business of mining, with the general anticipation that the work will be carried out without causing undue harm to the environment or populations in and around the mining operation. The term ?sustainable development? is gaining momentum as a popular concept, and indeed it has become something of a catch-all phrase, but it is important that the idea behind the term is not cast aside as a nonsense buzz word, as it simply is an indication that development (e.g. mining) can be satisfactorily carried out with an eye toward stewardship of the environment and society. On Feb. 19, 2010, a round-table discussion (Roundtable 2010) on ?Strides Toward Sustainability in Mining? was hosted by Knight Piésold and Co. (Knight Piésold) at the Red Lion Inn and Casino in Elko, NV. Knight Piésold had local representatives (Bryan Ulrich and Steve Boyce), as well as representatives from other office locations (Cynthia Parnow and Rick Damiani from Denver, CO, and Rick Frechette from Tucson, AZ) to help facilitate the discussion. The meeting played host to 30 attendees from five states. Attendees included personnel from nine mining properties and various corporate offices. The majority of participants were people who are directly involved with environmental work on a day-to-day basis. Others were project managers whose jobs involve some level of environmental focus.

Jan 1, 2010

By Hector Carreon

Due to elevated temperatures, excessive stresses and severed corrosion conditions, turbine engine components are subject to creep processes that limit the components life such as a turbine bucket. The failure mechanism of a turbine bucket is related primarily to creep and corrosion and secondarily to thermal fatigue. As a result, it is desirable to assess the current condition of such turbine component. By using eddy current images, it was shown that the eddy current technique could be used to monitor creep damage in a nickel base super-alloy. The eddy current results also show a significative variation in the electrical conductivity on the creep damage zone with respect to the background zone in nickel-base super-alloy samples. In addition, the absolute thermoelectric power coefficient show also a strong dependence associated with creep damage in nickel base super-alloy samples using a copper hot tip reference. The eddy current and thermoelectric power techniques seems to show promise as nondestructive evaluation tools for monitoring the level of creep damage in metallic alloys.

Jan 1, 2010

By Jay F. Colinet

Respirable dust exposure has long been known to be a serious health threat to workers in many industries. In coal mining, overexposure to respirable coal mine dust can lead to coal workers? pneumoconiosis (CWP). CWP is a lung disease that can be disabling and fatal in its most severe form. In addition, miners can be exposed to high levels of respirable silica dust, which can cause silicosis, another disabling and/or fatal lung disease. Once contracted, there is no cure for CWP or silicosis. The goal, therefore, is to limit worker exposure to respirable dust to prevent development of these diseases. The passage of the Federal Coal Mine Health and Safety Act of 1969 established respirable dust exposure limits, dust sampling requirements for inspectors and mine operators, a voluntary x-ray surveillance program to identify CWP in underground coal miners, and a benefits program to provide compensation to affected workers and their families. The tremen­dous human and financial costs resulting from CWP and silicosis in the U.S. underground coal mine workforce are shown by the following statistics: ? During 1970?2004, CWP was a direct or contributing cause of 69,377 deaths of U.S. underground coal mine workers. ? During 1980?2005, over $39 billion in CWP benefits were paid to underground coal miners and their families. ? Recent x-ray surveillance data for 2000?2006 show an increase in CWP cases. Nearly 8% of examined underground coal miners with 25 or more years of experience were diagnosed with CWP. ? ?Continuous miner operator? is the most frequently listed occupation on death certificates that record silicosis as the cause of death.

Jan 1, 2010

By J. J. Geraghty

U.S. Bureau of Mines researchers investigated the development of an innovative transport system for underground coal mining. A one-half commercial-scale bench model was constructed. Novel magnetic levitation (mag-lev) technology was developed. Frictionless and contact-free transport of a prototype materials container and payload has been demonstrated.

Jan 1, 2010

By Q. G. Reynolds

The problem of direct-current plasma arc behaviour, interaction, and dynamics is considered in the context of metallurgical DC arc furnace applications. Particular attention is paid to the transient flow behaviour of arc systems. A mathematical formulation of the physics used to describe the arc system is presented, and includes the spatial and temporal evolution of fluid flow, heat transfer, and electromagnetism. Based on this formulation, a numerical model is developed using a finite difference approach on a regular cartesian grid in both two and three dimensions, with a special focus on robust stability, high resolution modelling, and high performance. A collection of results produced using the numerical model to study pilot plant-scale furnaces is then presented. These address a range of process and design variables and their effect on the numerical model?s results. Where possible, the qualitative behaviour of the model is compared to available experimental data. A number of novel effects and phenomena are seen in the dynamic behaviour of the DC plasma arc model for both single and multiple arc systems, which may lead to improved understanding, control, and manipulation of such systems where they occur in industrial applications. Keywords Pyrometallurgy, direct-current furnace, plasma arc, modelling.

Jan 1, 2010

By T. Hollingsworth

The Boddington Gold Mine, located near Perth in Western Australia, has recently completed the construction of a new process plant. An overland conveyor system was installed to convey the ore from the primary crusher to the process plant. This paper will discuss the overland conveyor?s mechanical design including dynamic analysis and the selection of primary mechanical and electrical components.

Jan 1, 2010

By C. C. Clark

This report presents the results of tests conducted by the U.S. Bureau of Mines to determine the transport characteristics of highly concentrated paste backfill mixes made from dewatered total mine tailings. The slurry concentrations of the mixes were all above 78 pct by weight with slumps ranging from 6.4 to 16.5 cm (2.5 to 6.5 in). Laboratory material property tests and full-scale pumping tests were conducted using pipe diameters of 102, 128, and 154 mm (4, 5, and 6 in) and a positive-displacement pump. The results indicated that the tested backfill mixes can be successfully transported as a stiff paste and identified the influence of and the interaction among the various mix and system variables.

Jan 1, 2010

By Aline Maria dos Santos Teixeira

Serpentinite is an ultra basic and metamorphic rock consisting mainly of magnesium, calcium and silicon oxides. The rock under study is a host rock of chromite mine located in Andorinha, BA. The objective of this paper is to evaluate the rock's physical and chemical characteristics to be used as an additional fertilizer of acid soils. After comminution, rock samples were submitted to chemical analysis, XRD, SEM-EDS and TGA. Afterwards, particle size distribution was determined. Result analysis confirms that our rock consists mainly of dolomite, calcite and diopside. According to the result obtained, it can be said that the serpentinite rock has promising applications in agriculture for the correction and additional fertilization of acid soils. However, it is necessary to study the characteristics of the rock such as its dangers and toxicity as well as evaluate them according to the legislation for corrective acidity.

Jan 1, 2010