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With mine activity dating back to 1792, the Lehigh Valley, about 80 km (50 miles) northeast of the historic Allentown/Bethlehem steel mills and about 160 km (100 miles) northeast of Philadelphia, PA, defined early-day coal mining. Coal mining began just nine years after the end of America?s Revolutionary War. The high-carbon, clean-burning anthracite coal that was hand-dug from the Pennsylvania hills fueled the steam engines that powered the Industrial Revolution, helping build early steam ships and even the first automobiles. Around 1910, at the peak of the U.S.?s early mining effort, there were more than 250,000 men working underground ? 10,000 of them in the Lehigh Valley.

Jan 1, 2012

In this paper we present the results of preliminary investigations into the applicability of new laboratory scale tests for the prediction of operating gap and specific throughput in high pressure grinding rolls (HPGR). The work is a part of the CAMIRO HPGR research program being conducted at the University of British Columbia, which aims to develop a suite of small-scale tests and procedures for the selection and sizing of HPGRs. A focus of the presented study is to test sample types in terms of their terra-mechanics based characteristics and relate them to specific throughput and gap results from pilot HPGR testing on the same samples.

Jan 1, 2012

By E. Bakhtavar

There are many near-surface deposits with considerable vertical extent that have the potential to be mined by a combined method of open-pit and underground methods. In this regard, there is often a point called ?transition depth? where a decision has to be made whether to continue deepening the pit or change to underground methods. Recently, optimization of the transition from open-pit to underground operation has become an important challenge in mining engineering. Optimally, to model the transition problem on the basis of maximization of the profit from open-pit and underground mining, (0-1) integer programming has been used. In this method, block economic values of open-pit and underground methods should be imported to the transition model. A hypothetical example is presented in order to assess the model in detail.

Jan 1, 2012

By Russell R. McLellan

Under the Heavy Metals Program, investigations were conducted at the old Badger dill placer mini in Nevada County California to collect data and information regarding drilling and sampling methods and deposit characteristics. The studies contributed to a team effort by five Bureau of Mines research groups to develop new or improved placer mining technology in the Tertiary gold-bearing channel gravel of northern California. This report describes the techniques used and the results obtained in the sampling and drilling stage of deposit delineation studies that were conducted by the Denver Mine Systems Engineering Group. Sampling included the collection and processing of 400 tons of largo and small volume samples from drill holes, underground workings, surface pits, and blast hole rounds. A total of 355 samples averaging 2,296 pounds per sample provided reasonably accurate data for analysis of the gold distribution. These studies indicate that the bulk of the gold is within 40 foot of bedrock in stacked, lenticular zones of cemented gravel that are largely confined to the relatively narrow, meandering course of the deepest portion of the bedrock channel. Drilling studies involved the testing of three types of truck-mounted drills including rotary, bucket and vibratory, none of which proved to be a completely versatile tool for sampling quickly and reliably both consolidated and unconsolidated gravel.

Jan 1, 2012

Deciding on plant-scale reagent dosage regimes and air rates is a topic of ongoing investigation and high importance. The current work explains some techniques that have proven useful in deciding on plant-scale flotation operating regimes. Specific focus has been placed on the reagents: frother and depressant, as well as some discussion around the control of air rate and froth depth. Air rate has been selected based on its effects on the froth phase. Froth velocity and froth height above the cell lip are the two variables measured and used to select the operating air rate. Pulp level is then adjusted to increase or decrease mass pull. A technique has been developed using the Anglo Platinum Bubble Sizer on an industrial flotation cell to determine the relationship between bubble size and frother concentration. This technique has been extended to measure the equivalent frother concentration or frothabilities of various streams on a rougher bank. A mass balance for frother was performed successfully, and this provided a better understanding of the way frother moved in the rougher bank. With this knowledge, more informed decisions can be made about frother addition required in subsequent flotation stages. For depressant, a new protocol for deciding on dosage rate has been developed. The depressant dosage should be based on the amount of fresh feed material reporting to a bank. Currently 400 g/t of fresh feed has been assumed a reasonable starting point with promising results. Improved froth stability and grades were observed. There is scope for more accurately defining the optimal dosage rate. Importantly, the combined effect of changing the chemistry and the hydrodynamics together has been demonstrated. A significant upward shift in the grade-recovery relationship for a cleaner bank was observed.

Jan 1, 2012

By D. Van Tonder

ABSTRACT The comparative economics of ion exchange and direct precipitation have been analyzed by developing indicative CAPEX/OPEX models for typical alkaline leach uranium circuits. An agitated tank ore leach application is considered, comparing resin-in-pulp and direct precipitation as recovery options. Capital and operating cost estimates are derived from rates and factors used in recent studies and projects. The analysis showed the main economic drivers to be the ore grade and resin loading. The resin loading is impacted by the prevalence of competing ions, especially chloride. At resin-in-pulp solution chloride concentrations below 3 g/L and uranium grade below 640 g/t U3O8, resin-in-pulp is more economical, whereas at chloride concentrations above 3 g/L, direct precipitation is more economical.

Jan 1, 2012

By M. Moagabo

CO2 emissions from carbonate laden reclaimed mine spoil has been shown to pose a hazard to residents in homes built on or adjacent to such land. The objective of this project was to develop a soil CO2 flux survey protocol for assessing reclaimed mine land. The research involved CO2 chamber accumulation flux surveys; stable carbon isotope ratio analysis; statistical hypothesis testing to examine correlation between CO2 flux and soil temperature and moisture as well as spatial dependence; and geostatistics to map CO2 and delineate high flux zones. Soil temperature was observed to have a positive correlation with fluxes while soil moisture was observed to be negatively correlated. Spatial dependence of CO2 fluxes on reclaimed mine land was observed on one of the two study sites. The research suggests that macro-porosity and gas permeability may be important factors that explain CO2 migration in mine spoil. A flux survey protocol has been developed, based on these results, for reclaimed mine lands. The work demonstrates the capability of geostatistical methods to delineate high flux fields. Further research will be required to determine suitable thresholds for such analysis.

Jan 1, 2012

By Thomas Brynjulfsen, Merete Tangstad

"Manganese ore fines, generated during mining and transportation, can not be added to the submerged arc furnace directly as they will prevent even gas flow through the burden. Low gas permeability in the burden will lower the degree of pre-reduction of ore and subsequently increase the carbon and energy consumption of the process. In order to utilize manganese ore fines in the furnace they are agglomerated into sinter, pellet or briquettes. The agglomeration process will however change the reduction properties of the ore. In this work the melting and reduction properties of sinter has been investigated.The melting temperature and melting mechanisms has been studied. The mineralogy of the raw ores and agglomerated has been found using XRD, and the composition established using EPMA(WDS). The effect of adding fluxes such as dolomite and quartz has also been investigated.IntroductionManganese metal is produced in a submerged electric arc furnace or in blast furnaces. The reduction of manganese oxide in blast furnace has in the recent years become more unusual due to the high consumption of reducing carbon material[5]. Manganese metal for alloying in steel usually contains silicon and iron, and are therefore called ferro manganese and silicomanganese.During mining, transportation and handling the manganese ore is broken up into different size fractions. The larger lump are used directly in the electric arc furnace, but the finer materials can not be added without treatment. The fine ore can disrupt the flow of CO and CO2 gas through the burden, subsequently reducing the degree of pre-reduction. The fine fractions must therefore be agglomerated into larger lumps, in order to promote gas flow. This can be achieved through a number of different processes. The agglomerate used in this work has been sintered, which means that is has been partly molten and reduced, in order to create bigger lumps."

Jan 1, 2012

When a company like Lonmin, the third largest platinum producer in the world, is mining one of the most precious metals in the world, time is money. Every piece of equipment is expected to be in top shape because every minute of downtime can add up to lost profit. Two different types of platinum ore are mined and processed by Lonmin, namely Merensky and UG2. Merensky has a grade of 3.5 g/t (0.1 oz/st) and UG2 has a grade of 4.5 g/t (0.13 oz/st). The mine also produces platinum group metals (PGM), which consist of platinum, osmium, palladium, rhodium, iridium and ruthenium. Although South Africa has more than 80 percent of the world?s PGM reserves, these minerals are very scarce. Lonmin is considered a low-cost producer of these minerals, generating 21.5 t (694,000 oz) of platinum and 18.6 t (600,000 oz) of PGMs in 2012. So when the company?s Karee K3 concentrator plant in Rustenburg, North West Province, South Africa, was experiencing high operating costs on the transfer points, a solution was needed.

Jan 1, 2012

By Wen-Ming Chien, Vamsi Krishna Kamisetty, Amrita Mishra, Ivan Gantan, Prathyusha Mekala, Dhanesh Chandra

"The phase equilibrium and characterization studies by using high temperature X-ray diffraction (XRD) and differential scanning calorimetric (DSC) methods have been performed for binary organic thermal energy storage materials. The organic thermal energy storage materials undergo a solid-solid state phase transition before melting which stores large amounts of thermal energy. Two materials [tris(hydroxymethyl)aminomethane(TRIS) and 2-Amino-2-methyl-l, 3- propanediol(AMPL)] were used for this study. Binary samples of AMPL-TRIS were prepared to perform high temperature XRD characterization and DSC studies and the binary AMPL-TRIS phase diagram was developed. The high temperature solid-state phases of AMPL and TRIS were characterized as a disordered BCC structure. It was found there is virtually no solubility of TRIS in AMPL or vice versa below -75 °C. The maximum solubility of TRIS in AMPL is 11% TRIS at 75 °C. The eutectoid transformation was shown at 19%TRIS-81%AMPL composition and at a temperature of 75°C. Lattice expansion calculations on single phase of TRIS and AMPL have been performed.IntroductionThermal energy storage materials can store a large amount of heat due to the presence of thermal transitions from the orientationally ordered to disordered phases occurring before melting. These molecules (such as amine and alcohol derivatives of neopentane) can reorient as a whole about the central carbon atom to form orientationally disordered crystals (ODIC) and their spherical shape makes them reorient relatively easier. Thermal energy storage materials are becoming increasingly important as a renewable energy resource. These molecules undergo large changes in enthalpies at solid-solid transitions. The presence of these compounds with large enthalpy changes are identified as potential thermal energy materials and some of die applications are solar cell systems [1-3]. Binary mixtures have been found as a way to adjust the transition properties in addition to pure compounds [4]. Tris(hydroxyrnethyl)aminomethane (TRIS, C(CH2OH)3NH2) and AMPL, CH3C(CH2OH)2NH2) are two important thermal energy storage materials."

Jan 1, 2012

By Chri Rule

"This paper tells the story of the rapid commercial application of stirred milling technology at Anglo American Platinum’s many Concentrators. The first stirred mill – a 10 000 litre IsaMillTM; the largest at the time, was commissioned in late 2003. The project development work was presented at SAG 2001. This operation was “proof of concept” and vindicated the decision to scale up the technology; allowing a rapid and extensive roll-out of mainstream regrind mills as well as several further flotation concentrate regrind mills, over the next six years.Currently 23 stirred mills are in operation with 64 MW of installed drive capacity – this paper describes the projects’ roll-out and the significant results achieved to date. Many operational problems have been solved along the way, some of these will be described. The introduction of the technology has seen a step change in metallurgical results and progressively decreasing operating costs."

Jan 1, 2012

Two new inorganic-organic hybrid polymers, Al(OH)3-polyacrylamide (Al(OH)3-PAM) and Mg(OH)2-polyacrylamide (Mg(OH)2-PAM) were synthesized and successfully applied for the treatment of oil sand tailings. The results indicate that both Mg(OH)2-PAM and Al(OH)3-PAM were unaffected by the change in pH, and could be applied to oil sand tailings with varying sand-to-fine ratio (SFR). The optimum dosages for the Mg(OH)2-PAM and Al(OH)3-PAM were about 330 g/ton and 650 g/ton, respectively for SFR 3.75. The flocculated oil sand tailings dewater quickly producing 66-68% solids. The flocculated tailings produced similar filtration rate before and after shear. Mg(OH)2-PAM treated oil sand tailings produced twice the filtration rates (220 ml/min) compared with Al(OH)3-PAM. This study clearly indicates that Mg(OH)2-PAM and Al(OH)3-PAM is a viable solution while decreasing the mass-production of tailings and increasing the rate of water-recycle.

Jan 1, 2012

By Michael Wieland

Smoke/fume measurements from rapid transitory charge reactions are not wholly comparable with thermodynamic reaction code (TDRC) results, since quenched chemical reactions yield nonequilibrium concentrations. Though the work output and major reaction products are usually rendered with minor deviations, the toxic fumes and other minor concentrations reveal some major discrepancies. Work output for charge formulations in underwater or fixture tests were theoretically resolved with work-principal models that form a rough thermodynamic trajectory. Stalled nonequilibrium concentrations are rationalized by finding the underlying quenched reaction(s). The wide relevance of the Zeldovich radical-chain mechanism that transforms nitrogen oxide was previously recognized. The work-principal model (WPM) represents reaction quenching with off-trajectory constraints to render the fumes, without noticeably readjusting the work process. When restraints that characterize the confinement are WPM tractable, the resolution of critical reaction mechanisms is worthwhile, since they remain useful, regardless of the rich, neutral or lean stoichiometry of the charge formulation.

Jan 1, 2012

By Y. Mudryk, D. Paudyal, K. A. Gschneidner, V. K. Pecharsky, M. Khan

"Rare earth intermetallic compounds are utilized commercially as magnetic and battery materials, electron gun electrodes, etc. Several of these intermetallics will be briefly discussed. There are many other rare earth intermetallic compounds which are not utilized industrially but have unusual properties which are of fundamental interest and may have future technological applications. Several of these materials are discussed as well.INTRODUCTIONTens of thousands of rare earth intermetallic compounds exist, but physical properties (primarily their magnetic behaviors), other than their crystal structures have been measured for only a small percentage of these materials. Among these are the commercially important compounds: Nd2Fe14B, and the SmCo5 – Sm2Co17 family – well known high strength permanent magnets; (Tb0.3Dy0.7)Fe2, Terfenol-D, a giant magnetostrictive material; LaNi5Hx a critical component of the rechargeable Ni metal hydride batteries; and LaB6 an electron emitter. There are, however, many other intermetallic compounds which are not utilized industrially, but none-the-less, exhibit interesting, and sometimes, exotic physical properties which are of fundamental interest and may have some future technological significance. These include: the giant magnetocaloric effect compounds Gd5Si2Ge2 and La(Fe13-xSix)Hy; the RCu and RAg families of ductile intermetallics; the mixed intra-lanthanide (R,R')Al2 compounds in which magnetic transitions disappear and reappear as one R is substituted for by R'; and GdNi which exhibits large dilations along two crystallographic directions and a larger contraction in the third direction at the Curie temperature resulting in zero volume change as GdNi orders magnetically via a second order phase transition.COMMERCIALLY IMPORTANT INTERMETALLICSNdFeB Permanent MagnetsThe Nd2Fe14B permanent magnets were discovered in 1984 independently in the USA and Japan. It is a ferromagnet and with proper heat treatment and processing Nd2Fe14B is the strongest near room temperature permanent magnetic material known today. This intermetallic compound is utilized as a permanent magnet in many applications, such as electric motors (e.g. the modern automobile contains up to 35 electric motors), spindles for computer hard disc drives, microphones and speaker magnets for cell phones and other audio equipment, direct drive wind turbines, actuators, and Magnetic Resonance Imaging (MRI) units. There are two kinds of NdFeB permanent magnets – bonded and sintered. The bonded magnets have a lower magnetic strength than the sintered magnet. The highest strength magnets are obtained by small substitutions of Dy (up to a maximum of 10%) for Nd, because Dy can significantly increase the coercivity and thus the energy product (a measure of the magnetic strength or hardness). The bonded magnets account for about 12% of the NdFeB market (~82 metric kt per year, containing ~20 kt/a of Nd). The NdFeB permanent magnet market is growing at a rate of about 15% per year. (Burzo & Kirchmayr, 1989; Kobayashi & Hirosawa, 2001; Coey, 2011)."

Jan 1, 2012

By Peng Peng, Ouo Cheng, Guodong Lai, Lijuan Chu, Zebiao Zhang

"The pressure acid leaching residue of zinc concentrate contains a large quantity of sulfur. The present study attempts to leach sulfur using a mixture of ammonium sulfide and water solution at 25°C. Effects of three leaching variables: ammonium sulfide concentration, leaching time, liquid/solid ratio on the sulfur leaching rate were investigated. The process conditions were optimized using response surface methodology based on the central composite design. From the analysis of variance (ANOVA), the significant factors on response were identified. The optimum conditions for leaching elemental sulfur from pressure acid leaching residue of zinc concentrate were obtained using an ammonium sulfide concentration of 2.5 mol/L, leaching liquid-solid ratio of 6.5:1 and leaching time of 7 min. Under the optimum experimental conditions, a maximum of 98.50% of total sulfur was extracted. The experimental results obtained agreed satisfactorily with the model predictions, with a correlation coefficient (R2) of 0.99.IntroductionSulfur is widely used in agriculture, medicine, rubber, building materials, gunpowder, wine and sugar, and other fields [1]. Currently the world sulfur production is 40Mt, out of which more than 90% is recovered from industrial processes, and 10% is natural [2], This highlights the importance of sulfur recovery. As the pressure leaching technologies [3] continue to mature and are increasingly applied to refining, a large quantity of high-sulfur residue is produced [4-5]. It is desirable to recover sulfur from this residue, so that it is economically advantageous, and reduces environmental pollution [6]."

Jan 1, 2012

By A. Yazadni-Chamzini

Risk ranking of projects is one of the importance parts of the complicated risk management procedure. Recognizing the riskiest criteria enable the managers to plan for risk reduction. The first stage for meeting this aim is defining the risky parameters and then working to establish order between them. There are variety methods for risk ranking. The ELECTRE method is one of the best among the multi criteria decision making methods. In this paper with implementing the fuzzy ELECTRE, The risky criteria in the Tehran Subway project are being ranked. The result of this research presents damage and accident of machineries as well as the lack of labor and equipment safety is located in the first order. Collapse factors and local prices are in second rank. Also wrong design, pollution, urban facilities damageable are in third to fifth respectively. Delay and ? are located in the last positions.

Jan 1, 2012

By Ihsan Berk Tulu

In the Analysis of Retreat Mining Pillar Stability (ARMPS) program, the magnitude of the abutment loading adjacent to a gob area is calculated using an ?abutment angle? concept. The extent of the abutment loading is determined solely as a function of depth from an empirically derived equation. In the recommended calibration method for LaModel, it was believed that the empirical equations for calculating the magnitude and extent of the abutment load, as used in ARMPS, were the best available methods for determining these critical overburden loading values. Therefore, similar calculations were implemented in the LaModel calibration method. However, the latest in situ stress measurements of abutment loading performed in the United States and Australia have shown that there can be significant deviations in the measured abutment magnitude and extent as compared to the predicted values from the empirical formulas used in ARMPS and LaModel. It seems reasonable that the overburden geology, depth, extraction panel width, and mining height should have a significant effect on the extent and magnitude of the abutment load. However, the current empirical formulas do not incorporate many of these significant parameters into determining the abutment load on the pillars. In this paper, stress measurements from US and Australian mines were back-analyzed by using analytical and numerical methods to investigate the measured abutment extent and loading. Ultimately, it was determined that the original empirical abutment extent formula in conjunction with the original ALPS square-decay stress distribution function was supported by the case histories in this paper. Also, for depths less than 900 ft, the average 21° abutment angle was supported by the case histories; however, at depths greater than 900 ft, the abutment angle was found to be significantly less than 21° and should be calculated with a new proposed equation.

Jan 1, 2012

By M. B. Shongwe

Pt-based alloys are being developed for high-temperature applications with the aim of replacing some of the currently used Ni-based superalloys (NBSAs) in the highest temperature applications. The Pt-based alloys have a similar structure to the NBSAs, and since Pt is more chemically inert than nickel and has a higher melting point, they can potentially be used at higher temperatures, up to 1300°C, and in more aggressive environments. Several experimental Pt-based alloys were studied at Mintek, and an optimum composition was found to be Pt84:Ahi:Ru2:Cr3 (at.%). On the basis of hardness and microstructure, a later study identified a new optimum: Ptr8:A111:Ru5:Cr6 (at.%). There are at least two Pt3A1 allotropes, and the high-temperature cubic structure has better properties than the lower temperature tetragonal form, and so needs to be stabilized. This work describes the latest results obtained in transmission electron microscopy (TEM) studies of the quaternary Pt-based superalloys. These results are both interesting and important, because the samples have a higher precipitate density compared to those from earlier work. The precipitate morphology is mainly cubic, with minor areas having irregular-shaped precipitates. The high volume fraction of the precipitates is a major breakthrough, since the objective of this work is to improve the alloys. A prior disadvantage was that the proportion of the precipitates was too low in samples before this work, especially compared with the work from Germany on Pt-Al-Cr-Ni¬based alloys as well as the NBSAs. TEM -Pt3A1 diffraction patterns were studied, and for each diffraction pattern, many possible lattice point combinations were tried, with the angle between the lattice spots as well as interplanar spacings being calculated for each phase (cubic or tetragonal) to match the measured results. An overall analysis of the diffraction results indicates that the cubic phase fitted the experimental lattice points with much lower errors compared to the tetragonal phase. Thus, with the close match achieved with the cubic structure, the structure of -Pt3A1 precipitates is likely to be cubic. X-ray diffraction has been carried out on selected samples, and the results confirmed the presence of cubic -Pt3A1 and (Pt). Different X-ray diffractometers were used to further verify the results, and the results were also compared with those from TEM.

Jan 1, 2012

By Cynthia Belt

"Energy management is critical to aluminum processing given the high energy requirements of melting and processing aluminum. Energy costs have always been a high percentage of the total production costs within this industry. Energy management at many plants relied on better technology that many times required high capital. As carbon management has grown in importance and project payback becomes more critical, a larger view of a plant's process is required. This paper looks at the energy requirement due to current typical practices in overall product recovery, metal loss, utilization, and technology to understand potential methods of reducing overall energy within a plant and within the aluminum processing industry.IntroductionFor many companies that process aluminum, energy is a major portion of their costs that can surpass the cost oflabor. Aluminum processing can include secondary processing of scrap and prime aluminum into sows and/or molten aluminum or casting aluminum by various methods such as direct chill, continuous casting, low or high pressure casting, mold casting, and extrusions. In the case of this paper, we are considering only plants that include the melting process as a portion of their process. The process of melting aluminum takes energy. In most cases, the aluminum must then be heat treated one or more times. Post processing of the aluminum includes rolling mills used for making sheet, extrusion lines, and machining such as saw cuts, drilling, or surface finishes that all take additional energy.While these high energy costs directly affect the profits of the company, energy management within the metals industry is still not widespread. A co=on misconception is that the solution to high energy costs is high cost capital equipment. While state-of-the-art equipment can certainly improve energy efficiency, it is not the only solution. To obtain a truly energy efficient plant, several directions needs to be addressed through an energy management thought process with a wider scope. Impact on potential savings is possible through: product recovery, metal loss, utilization, and new technologies. An understanding of the potential costs and savings from these means is important. Several of these methods provide low cost approaches to saving energy.The background data used in this paper is not a random sample within aluminum processing but yearly averages from various plants in different aluminum processing industries. As is normal in this industry, the plants have been under different corporate management over the years with different strategies for energy management. This data is not meant to be accurate for the entire industry but to suggest areas for energy efficiency work."

Jan 1, 2012

By M. T. Webster

Views about the proper aim of public policy are, of course, matters of perspective and debate. Regardless of perspective, one would assume some consensus around the view that public policy ought to encourage mine operators to seek independent and critical assessments of worker safety and health at their operations through voluntary auditing. However, a review of the law on this topic shows that there is little to no manifestation of such a policy. Indeed, the balance of this paper, with a couple of exceptions, is devoted to the existing legal pitfalls that should be considered before a safety and health audit is conducted at a mine. While attorneys, particularly litigators like the author, might tend to focus on the potential problems that could arise from any given situation, the fact that most of this paper is devoted to potential legal concerns associated with auditing is a realistic reflection of the current state of the law. Specifically, this paper addresses the interplay between voluntary safety and health audits conducted at mines regulated by the Mine Safety and Health Administration (MSHA), and the administrative and civil legal issues related to such audits. The paper first provides an explanation of how and by whom an audit is conducted. The paper also addresses whether voluntary safety and health audits may be considered privileged and kept confidential in administrative and civil proceedings. Finally, selected legal issues related to such audits that could arise in administrative and civil litigation are discussed.1

Jan 1, 2012