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By Linda Gaines

Use of vehicles with electric drive, which could reduce our oil dependence, will depend on lithium-ion batteries. But is there enough lithium? Will we need to import it from a new cartel? Are there other materials with supply constraints? We project the maximum demand for lithium and other materials if electric-drive vehicles expanded their market share rapidly, estimating material demand per vehicle for four battery chemistries. Total demand for the United States is based on market shares from an Argonne scenario that reflects high demand for electric-drive vehicles, and total demand for the rest of the world is based on a similar International Energy Agency scenario. Total material demand is then compared to estimates of production and reserves, and the quantity that could be recovered by recycling, to evaluate the adequacy of supply. We also identify producing countries to examine potential dependencies on unstable regions or future cartels.

Jan 1, 2010

By Liming Yuan

Barometric pressure changes affect air density, leading to change in the mass of the gas in the gob. When the barometric pressure decreases, the volume of gas in the gob expands, while the volume of gas contracts when the barometric pressure increases, causing the gob to breathe out and in. Although the concept of gob ?breathing? is simple, its effect on spontaneous heating of coal in the gob area is not clear. In this study, computational fluid dynamics (CFD) simulations were conducted to model the spontaneous heating of coal in longwall gob area under measured barometric pressure changes. A single longwall panel using a bleederless ventilation system was simulated. If there is no barometric pressure change, the intake airflow rate is equal to the return airflow rate. When the barometric pressure changes, these two airflow rates are no longer equal, and the difference between the two airflow rates represents the airflow rate the gob breathes in and out. The effect of inflow and outflow of gas on the potential spontaneous heating in the gob was investigated using the CFD model developed in our previous study. The effect of barometric pressure changes on the spontaneous heating was found to be dependent on the gob permeability and the coal oxidation rate. The effect of barometric pressure changes on oxygen concentrations in the gob was also examined.

Jan 1, 2010

By Jay W. Hawkins

Under an approved remining program, mine operators can remine abandoned coal mines without assuming legal responsibility for treatment of the previously degraded water, as long as the discharging waters are not further degraded and other regulatory requirements are satisfied. A U.S. Bureau of Mines review of 105 remining permits in Pennsylvania indicates that remining results in substantial reclamation of abandoned mine lands, utilization of significant quantities of coal, and reduction of contaminant loads (acidity and iron) from degraded mine drainage discharges. Normality tests performed on the water quality and flow data indicate generally nonnormal distributions and extreme right-skewness, tending toward lower values. The water quality of underground coal mines was observed to be more highly degraded in terms of acidity, iron, and sulfate than that of surface coal mines. The optimum baseline sampling scenario is 12 months in duration at a frequency of one sample per month. Analysis of water quality and flow rates before and after remining indicates that a majority of the mines exhibited either no change or a significant decrease in pollution rate because of remining. The discharge flow rate was the dominant controlling factor when the post-remining contaminant load was significantly better or worse than the baseline (pre-remining) load.

Jan 1, 2010

By J. W. Bridge

Triaxial compression tests at various confining pressures and temperatures, as well as tangent modulus tests using ultrasonic waves, were conducted for wax-coated granular composite materials. The material used is a surface for Thoroughbred horse racing. The purpose of these tests is to examine how track shear strength and tangent modulus at a range of loads respond to changing temperatures. Previous work has shown that a wide range of operational temperatures are experienced which have been reproduced in the lab. Using differential scanning calorimetry, it is confirmed that these operational temperatures correspond to distinct thermal transition regions for the wax that is used to coat the sand in these surfaces. Preliminary results show that both shear strength and tangent modulus are sensitive to temperature changes with maximum strength and modulus correlating with major DSC wax transition regions.

Jan 1, 2010

By H. Maleki

This paper recognizes the 100th year of research accomplishments by the mining industry resulting from close cooperation among mining companies, geotechnical consultants and researchers from the former United States Bureau of Mines in stability assessments and development of improved and productive mine designs. The paper provides an overview of dramatic developments in geotechnical instrumentation, and its applications in the U.S. and around the world for enhancing the understanding of ground response to mining-induced changes in stress, resulting in improvements in ground control technologies.

Jan 1, 2010

By Gabrielle Gaustad

For aluminum, substitution of primary with secondary resources decreases energy consumption; this energy advantage creates a strong economic incentive to recycle. Several authors have raised concerns that the current sinks for secondary materials may soon be saturated, impeding subsequent expansion of recycling. This work combines dynamic material flow analysis with optimal batch planning models to quantify the significance and drivers of these pending limits under several scenarios, and thereby explore potential opportunities to increase recycling. An aluminum recycling system case was developed that includes containers and packaging, automotive, and construction products and scraps. The impacts on aggregate scrap utilization and materials cost are explored in the context of changing alloy demand and lifetime. Insights drawn from this specific case study could be applied to multi-stakeholder, systemic models.

Jan 1, 2010

By M. Steyn

This article captures the intrinsic differences of thermal coal products, their utilization and their substitution characteristics. South Africa produces approximately 245 million tonnes of coal annually. Eskom consumes 46% (approximately 112 million tonnes), 26% (approximately 65 million tonnes) is exported, and SASOL Synthetic Fuels consumes 18% (approximately 44 million tonnes) and a further 9% (approximately 22 million tonnes) is consumed by domestic users in various different industries. Marketing theory contributes significantly to understanding the importance of technical product and quality appreciation and comprehension, encompassing elements of price, distribution, and promotion. Coal product specification is determined by the inherent geology of a resource and the number of complex actions to market the product to a specific consuming market. Sampling, analyses, beneficiation application, and an array of parameters contribute to matching thermal coal products to the value-in-use it provides to the different markets and its consuming industries. Coal producer shave come under increased scrutiny since South Africa has been experiencing electricity shortages since early 2008. General misunderstandings were declared on public forums and in the media by both legislators and the South African public since a perception developed that South African coal producers are exporting coal that could be utilized by Eskom.

Jan 1, 2010

By D. J. MacDonald

As part of a U.S. Bureau of Mines program seeking improvements to the Bayer process, a typical Jamaican bauxite was heated at temperatures up to 500° C in hydrogen, and its leachability under Bayer process conditions was measured and properties of its leached residue were observed. The objectives were to find ways to decrease the amount of organic carbon in bauxite or in leach liquor derived from it without impairing its leachability, and to improve the leached residue's filterability. Techniques employed included heating bauxite under pressure in an autoclave with hydrogen, and in flowing hydrogen at ambient pressure in a tube furnace. Leaching tests were done with a 600-mL stirred reactor. In some of the leaching tests, ferrous sulfate (FeS04) was introduced before leaching to produce a partially magnetic product. Results showed that exposure to hydrogen at temperatures from 160° to 360° C progressively diminished the bauxite's content of organic carbon and decreased the ratio of organic carbon to aluminum in leach liquor, an improvement that would allow a process using hydrogen-treated bauxite to be operated at a smaller recycle ratio, thereby consuming less energy and allowing greater throughput for a plant of given capacity. The bauxite's leachability was not impaired by high-temperature pretreatments, except at temperatures higher than 280° C. Pretreatments in hydrogen produced black, partially reduced bauxite which upon leaching gave a residue that was attracted to a magnetic field and was amenable to separation from green liquor by a magnetic filtration method.

Jan 1, 2010

By C. Butcher

Numerical simulations of straight tube hydroforming of a dual phase steel were performed using both upper and lower bound constitutive models for porous ductile materials. The Gurson model is based upon an upper bound approximation to the material behavior and thus overestimates formability. Conversely, a lower bound solution to Gurson's unit cell geometry was developed by Sun and Wang to provide a conservative estimate of formability. The effect of a compressive axial load (end-feed) on damage development and tube formability is investigated. The resulting upper and lower bound models successfully captured the experimentally determined burst pressure, formability and failure location.

Jan 1, 2010

By B. Clermont

Ball mills are usually the largest consumers of energy within a mineral concentrator. Comminution is responsible for 50% of the total mineral processing cost. In today?s global markets, expanding mining groups are trying to optimize mill performances. Since comminution is concerned with liberating valuable minerals for recovery in the separation process, it is crucial to run the mills at the best operating conditions which lead to good liberation at competitive throughputs with minimum costs (energy and wear). The high availability of the equipment is also essential to maximize production and profit. To reach this key objective, continuous and reliable information about the mill operation is vital. An innovative tool which can deliver information about in-mill dynamics has been developed by Magotteaux. It can provide online and accurate measurements of the degree of grinding ball fill and pulp position for timely decision making and actions. This tool could be used on its own or linked to an automatic grinding ball loading system named Magoload. Therefore, ball load could be kept constant by using direct measurement. This article describes the Sensomag and presents some of the major improvements that can be achieved with it. Some other promising avenues are still to be explored. Keywords: Comminution, process control, process optimization, process instrumentation, online analysis.

Jan 1, 2010

By V. R. Shea-Albin

This U.S. Bureau of Mines report discusses elastic wave velocity and attenuation behavior as an indicator for changes in load and structural integrity of coal samples. Measuring changes in compressional (P)-wave and shear (S)-wave attenuation and velocity under uniaxial and triaxial compression tests revealed their effectiveness for distinguishing changes in applied load and structural failure of samples. The velocity and attenuation values were used in further calculations such as ratios of P-wave to S-wave values, dynamic elastic constants, normalized velocities, and attenuation coefficients to reveal trends for loading and failure. The behavior of both P-wave and S-wave attenuation and velocity together define distinct and consistent phases of load change and failure for uniaxial and triaxial tests. The S-wave velocity and attenuation illustrate changing axial load and initial development of microfractures within the sample preceding structural failure more clearly than those of the P-wave. The attenuation and velocity ratios and dynamic elastic constants (except the bulk modulus) respond to closure of small preexisting fractures within the coal sample with initial loading to failure of coal samples. The attenuation coefficients and normalized velocities reveal trends similar to those shown by velocity and attenuation.

Jan 1, 2010

By Lucas Lopes da Costa

In this work, a natural foam extracted from the Amazon buriti palm tree is investigated as possible substitute for synthetic foams. The basic physical and mechanical properties of this biofoam were evaluated. Its sponge-like structure was characterized by the amount of pores and morphological aspects. It was found that the buriti biofoam displays a very low density of the order of 0.1 g/cm3 with a relatively good compressive strength. This would be suitable for several engineering applications and as a new material with the potential for replacing currently applied synthetic polymeric foams.

Jan 1, 2010

By Gerard McAlinden, Daniel Frost, Patrick McAlinden, James McAlinden

In an effort to recover Polychlorinated biphenyls (PCB’s) that had leached into bedrock below the Hudson River in Upstate New York, a shaft and tunnel complex was designed that would allow installation of inclined and vertical wells into the zones of contamination to recover PCB’s by gravity. A joint venture of Merco Inc., of Lebanon, NJ, and Obayashi Corporation, of San Francisco, CA, was awarded the contract for constructing the first Tunnel Drain Collection System in the world. Conventional drill and blast techniques were the most economical method to construct the project but due to the presence of PCB’s and community concerns, innovative drill and blast practices were needed.

Jan 1, 2010

By Brian Hart, Stamen Dimov

"The Time of Flight Secondary Ion Mass Spectrometer (ToF-SIMS) is unique in that it measures the outermost atomic layers of any material. The technique is particularly suited for determining surface chemical composition of mineral particles. It is most commonly used as a diagnostic tool to measure mineral surface chemical variability in plant and bench top flotation separation processes. Recently, research towards understanding the full capability of the instrument has resulted in the development of new diagnostic applications related to various Au extraction technologies and the development of the ToF-SIMS as a predictive tool for assessing the chemical reactivity of the ore.In this paper we will present a brief review of the ToF-SIMS technique with recent advances in instrumentation and methodologies including:•,?recent developments and advances towards a semi-quantitative approach to the evaluation of mineral surface modifiers (ex. Cu),•,?flotation case studies investigating activator, depressant and collector loading variability within a flotation process,•,?the recently developed chemical reactivity test which we believe has the potential to predict the behaviour of minerals in a flotation test in response to chemical transfer during grinding,•,recent applications for determination of surface Au preg-robbed in carbonaceous materials.A portion of this material has been recently presented at the COM 2009 meeting and at SIMS XVII (see Dimov et al 2009 and Hart et al, 2009).INTRODUCTIONIn flotation seperation surface chemistry is the principal determinant for selective separation of the various mineral phases (Ralston, 1994, Smart et al, 2003). Determination of this hydrophobic/hydrophilic balance by particle therefore requires correct identification and selection of the particular mineral phase(s) followed by a statistical analysis of the surface chemical characteristics of the particles with an estimation of the spread of values (Smart et al, 2003)."

Jan 1, 2010

By T. G. Sitharam, P. B. Choudhury

Prediction of ground vibration (peak particle velocity, PPV) and frequency is an important task in geoscience. Till date, many empirical equations are derived from conducting trial blasts in the mines, to arrive at attenuation predictors. These predictors are usually site dependant and hold good for one particular type of rock/strata. These predictors cannot be used for geologically different rocks/strata. This paper presents the application of support vector machine (SVM) model, for predicting blast induced ground vibration and frequency, using a one comprehensive model for three different types of rock. Inputs to the SVM model formulation involve twenty one parameters consisting of geotechnical properties of the rock mass, blast design geometry and explosive properties, and the output of the formulated model is peak particle velocity and its associated frequency. The data has been acquired from eight limestone mine, five coal mine and two manganese mines. The comprehensive SVM model is formulated using 400 datasets and tested with 143 datasets. The performance indicators to the model not only justify its formulation but also the advantages it has over site specific predictor models. The SVM model not only predicts PPV, with higher correlation coefficients as compared to predictor equations, but also the associated frequency.

Jan 1, 2010

By Z. G. Lin

In Xian, China, compaction by means of soil (or lime-soil) piles is one of the effective methods widely used for densifying loess and eliminating its collapsibility. However, as a result of groundwater table rising, it is no longer applicable in many areas. This paper is the summary of the first-time use in Xian of sand-gravel compaction piles aimed at densifying the miscellaneous fill (already partially under water) and saturated loess at a certain project site. In-situ tests, conducted before and after the treatment and including several kinds of penetration tests backed up and confirmed by a set of plate loading tests, yielded very satisfactory results, strongly testifying to the viability of the method.

Jan 1, 2010

By S. L. de Moraes

This study aimed to identify a way to reduce the use of bentonite in the pelletization of magnetite. With this goal, different combinations of binders were compared to bentonite by examining the quality of pellets obtained by balling drum agglomeration. Pellets were subjected to routine tests that included simple compression of the wet and dry 105°C pellets, dropping wet pellets to determine their ability to survive handling and submitting pellets to thermal shock to determine how they tolerate drying and preheating. The best results use sodium silicate (1.5%) as a binder and show that it is possible to pelletize iron ore without using bentonite.

Jan 1, 2010

By Kewal K. Kohli, Stefanie Self

"Three cases of surface subsidence investigated over abandoned coal mines after flooding in one case and dcwatering in two cases are presented in this paper. Mining was conducted by the room and- pillar method at all the mines leaving stable pillars. This paper will discuss the background chain of events and the likely causes of the pillar failure resulting in surface subsidence.CASE NO.1BackgroundThe Pittsburgh scam was mined in 1960 by the room-and- pillar method, leaving pillars (Figure I) through Mine A. located in Monongalia County. West Virginia.The mining height in U1is area was 1.83 m (6 ft) with an average mining depth of 140 m (460 ft). The mining recovery was 62% and the safety factor of the pillars was calculated at 1.15 using the Bieniawski ( 1984) fom1ula. For stable pillar design. a 1.5 safety factor is recommended. A 1.15 safety factor is considered marginal. Pumping continued after the mine was shut down in 1960 to prevent water seeping into an adjoining mine owned by the same company. The pumping ceased on December 12. 2003, and the mine was allowed to flood. The water level rose about 17 m (55 ft) by August 3 1, 2004, based on observations in a nearby borehole. On September 3, 2004 surface subsidence occurred above this area causing damage 10 a residence (Figure 2).Summary of InvestigationThe floor of the Pittsburgh coal scam played a strong role in the pillar failure. In this area, the immediate floor of the Pittsburgh seam consists of about two feet of fireclay. Extensive damage to the surface house was an indication that a major collapse below the surface had occurred. The pillars supporting the overlying strata were evaluated to find the cause of their failure. The pillars in the Pittsburgh seam (sec Figure I) had a marginal safety factor of 1.15 before flooding and were stable for 26 years. Once the mine was flooded the water level in the Pittsburgh seam rose by 17 m (55 ft). Shortly thereafter the fireclay in the floor weakened, resulting in several pillars punching into the floor unevenly making the immediate roof unstable. The overburden strata supported by these pillars also subsided do"" n into the mine, causing damage to several house on the surface."

Jan 1, 2010

By Karel Van Acker

The automotive is a sector where energy consumption during the use phase prevails over the production and the end-of-life phase. Therefore, a lot of research and innovations at replacing classical steel parts by lighter materials like light metals and polymer composites. While composites are very attractive for the use phase of cars, their introduction suffers from the limited end-of-life options for composite structures. An extensive life cycle analysis for a reference car design has been conducted to study the effects of replacement of conventional steel structures by lightweight carbon fibre composite alternatives. The study also takes second order effects in the design of the car into account. The opportunities and treats of the trend towards more intensive use of carbon-fibre composites in car design are identified. A discussion on the potential of other types of composites for the automotive in terms of sustainability considerations is added.

Jan 1, 2010

By D. N. Ferguson

The separation of certain minerals by electrostatic techniques can be difficult due to their similar electrical conductivity, and any technique to improve this can be useful in certain difficult separation applications. Triboelectric differences between mineral scan result in certain minerals acquiring small positive or negative charges prior to inductive electrostatic separation. By changing the polarity of inductive separation, relative changes in mineral recovery can be observed, which may be beneficial. In this brief study a JKTech mineral liberation analyser (MLA) was used to evaluate the effect of polarity change on selected minerals present in the Richards Bay Minerals deposit, and an approximate triboelectric series based on this behaviour is presented.

Jan 1, 2010