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By Michael Karmis

"In December 2011, the U.S. Attorney’s Office for the Southern District of West Virginia, the U.S. Department of Justice, Alpha Natural Resources (ANR) and Alpha Appalachia Holdings entered into a nonprosecution agreement related to the explosion at the Upper Big Branch Mine (UBB) that killed 29 miners. This coal operation was owned by Performance Coal Co., an affiliate of Massey Energy Co., which was acquired by ANR in June 2011, more than a year after the UBB explosion. Pursuant to the agreement, ANR agreed to:• Establish a trust within 120 days.• Pay a total of US$48 million into the trust to be used solely to fund and administer research and development (R&D) projects to improve mine health and safety.• Administer the trust by three highly qualified individuals with academic and/or professional backgrounds in mine health and safety.In April 2012, the Alpha Foundation for the Improvement of Mine Safety and Health was created. The three directors - Michael Karmis, president; David Wegman, vice presidenttreasurer, and Keith Heasley, vice presidentsecretary - approved a plan to expend both the interest and principal of the trust, aiming at an 8-10 year research horizon. The foundation also appointed David Belden, an experienced manager of nonprofits and professional associations, as the first executive director of the foundation. The IRS approved the foundation’s tax-exempt application, as described in Section 501c(3) of the Internal Revenue Code, on Dec. 18, 2012. The board established guiding principles of the foundation, which are as follows:• Mission: to improve mine health and safety through funding R&D projects to qualified academic institutions and other not-for-profit organizations.• Vision: to enable miners in the future to be free of work related injury or disease by the implementation of the results of the projects funded by the foundation and undertaken by the best researchers from any discipline that can contribute. The foundation is now approaching its third year and regularly posts updates, including semi-annual reports, to its website (www.http.alpha-foundation.org/), which serves as the main medium for communication with the broader stakeholder community"

Jan 1, 2014

By Kozlov Andrey, Matveeva Tamara

"The results of mineralogical and technological studies of platiniferous dunites from Svetloborsky zonal massif (Urals platinum belt) are presented and the basic typomorphic signs of productive mineral assemblages are substantiated. The characteristic features of platinum ore mineralization are revealed: a wide range of iron-platinum alloys, enrichment of ore-formed system by the elements Os, Ir, Rh and activity of the S and As in it, intrusion of Fe-Ni sulfides in platinum and its fusion with magnetite. More than 80% of PGM mineral grains has size less than 100 microns, that determines the possibility of significant losses of platinum in the process of gravity separation and the need for additional recovery processes for small and fine fractions of platinum tailings and sludge products. Summarized results of laboratory tests of small-volume sample processing of platiniferous dunites are presented and the processing flow sheet is developed and tested. The flow sheet incorporates several stages, including stage-wise grinding and gravity separation of ore using the centrifugal concentrator Knelson KS-MD for differently sized material and flotation treatment of tailing products using new classes of reagents for additional recovery of PGM fines."

Jan 1, 2014

By A. Alfantazi, L. Choudhary

Gold leaching in thiosulfate solution has attracted widespread research interest through the last two decades primarily due to its perceived environmental benefits in comparison to the conventional gold cyanidation technique. However, the data on the corrosion and/or corrosion-induced failures of plant infrastructure materials in the solutions relevant to thiosulfate gold leaching are very limited. Accordingly, this study aims to characterize the electrochemical corrosion behavior of stainless steel 316L in the thiosulfate gold leaching solutions. Electrochemical corrosion response was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy. The morphology of corroded specimens was analyzed using scanning electron microscopy.

Jan 1, 2014

By Fangtian Wang

The fully mechanized longwall mining was employed in a shallow coal seam that was under the gobs of room and pillar mining and overlain by thin bedrock and thick loose sands. Operational practices have demonstrated that severe accidents would occur including roof structure instability, roof steps, damages of shield supports, and face bumps triggered by the large area roof weighting, resulting in serious threats to the safety of underground miners and equipment. This paper uses Shigetai Mine, located in the Ordos area, Inner Mongolia, as the study site. It fully considers the geological conditions of 3-1-2 coal seam and employs theoretical analysis, 3DEC numerical simulation, and field measurements to analyze the overlying strata movement for the shallow seams under an abandoned room and pillar mine without pillar extraction. The research results serve as an excellent guide to mining in similar geological and mining conditions.

Jan 1, 2014

By Luis Bergh, Iván Rojas, Juan Yianatos, Luis Vinnett

"At present, flotation rate characterization follows standard measurements to identify the overall flotation performance looking at the feed, tailings and concentrate in flotation cells or banks. This classical approach does not take into account the evolution of the true collection rate down the flotation banks explicitly. The potential for identifying the impact of the mineral characteristics (size and liberation) as well as the effect of different manipulated variables (reagents, froth depth, gas dispersion) on the true flotation process remains hindered. Top-of-froth (TOF) measurements, which consist of sampling the first layer on the froth surface, have been used to characterize the mineral collected by true flotation in rougher banks. The information provided by TOF samples allows evaluating the floatable mineral evolution (grade, particle size, liberation) down the bank. In this work, an indirect approach to estimate the flotation rate along rougher flotation banks is proposed. The new approach is based on the decreasing of collected mineral grades (on top of froth) and the feed characteristics. Flotation rates per liberation classes were used to reconstruct the TOF grades from the feed information. This approach requires a simple froth surface sampling, without constraints typically observed during mass balance surveys and uncertainties on the mineral recovery estimation. The proposed methodology was successfully applied at industrial scale using TOF measurements together with QEMSCAN information."

Jan 1, 2014

By Al Cropp, Julie Hunt, Will Goodall, Ron Berry, Dee Bradshaw

Geometallurgy aids the understanding of ore body variability but has the most value if the data is easily available along the entire mining value chain. This requires cross-discipline communication and collaboration across traditional silos, and an organizational culture that encourages that to flourish. Data that are collected by the numerous groups (i.e. mining, geology, milling, processing, refining, smelting, marketing, environmental etc.) involved in the mining process may have relevance to other stakeholders; mineralogical and textural data for example has value to all these groups. Data required for modeling comminution or identifying acid potential from waste rock may already exist, however it needs to be made available to all the relevant stakeholders in the right format at the right time. As part of the GeM (AMIRA P843 & P843A) project the opportunity has been taken during the sponsor meetings, short courses, case studies etc. to ask the question: ‚What information do you want from further up the chain?? For example, to metallurgists ‚What information would you like from the geology group before the ore enters the mill?? The geology group may already have information important to mineral processing but not know it is of interest. This could, for example, be in the form of a geometallurgical drill core log that contains quantitative measured values. This paper focuses on the interaction between the mining, geology, mineral processing and environmental groups, using ore properties resulting from geological alteration to identify potential impacts throughout the mining process and discusses how a cross discipline approach can benefit all.

Jan 1, 2014

By Emily Wortman-Wunder

While the mood at the 2013 annual joint meeting between the Pittsburgh Coal Mining Institute of America (127th Annual Meeting) and SME Pittsburgh Section (68th Annual Off-the-Record Meeting) in Canonsburg, PA was subdued following a rocky year in the coal industry, attendance was down only slightly, to 300, and overall, the meeting?s focus was optimistic about the future of coal. The conference began by addressing one of the central challenges of coal mining head-on with a keynote address on the status of safety in the mining industry. Noting that two more U.S. miners had died in 2013 than by the same date in 2012, the National Mining Association?s (NMA) Senior Vice President of Regulatory Affairs Bruce Watzman made a plea for a new approach to safety. He described the NMA CORESafety initiative, a program that promotes proactive safety measures versus a compliance-driven model. CORESafety, described in more detail on pp. 29 of this issue, focuses on developing successful ways to change company cultures of safety and behavior. Other industries that have adopted this approach have seen dramatic drops in fatalities, including the Australian mining industry, which has seen its annual fatality rate drop to nearly zero even while the number of people employed in the industry has soared. The rest of the morning?s sessions explored what is arguably the industry?s biggest challenge right now ? maintaining the social license to operate.

Jan 1, 2014

By F. Bello, R. Yanez, M. Pinto, T. Errazuriz

"Throughout its operation, Minera Esperanza (ME) will deposit one of the largest tonnages rates of high density tailings in the world with a solids concentration of close to 67% by weight. The tailings presently being deposited have a solids concentration of approximately 62% - 64%, and so cannot be used to directly characterize the flow and deposition characteristics of the higher concentration tailings. To increase the knowledge of the behaviour of their tailings, ME, with the support of Golder Associates, developed a large scale tailings deposition test with a capacity of 30,000 tonnes per day (1,200 m3/h). The test was carried out by depositing tailings into two large cells or paddocks in five stages. Multiple spigots were used to allow different flows to be deposited. At each stage, topographical surveys of the natural terrain and the geometry of the deposited tailings, as well as continuous flow measurement and periodical rheological characterization of the discharged tailings were conducted to create a data set against which beach slope models could be calibrated and then used to predict performance of the higher concentration tailings under different deposition scenarios. This study adopted the beach slope prediction model proposed by A.L. Li (Li, 2011). The model was successfully adjusted to the observations made during this large scale field test by applying the values measured in-situ. This paper presents the application of the model, the results obtained, the findings, and the analysis of possible future scenarios. The model was applied, using the discharge flow rate, the geometrical characteristics of the discharge area, and the rheology with its variation along the beach to estimate the development of the beach formation and the steady state of the beach slopes. Through the use of dimensionless variables, the model was applied to higher solids concentration scenarios, obtaining results that would allow beach slope estimation at different deposition stages in multiple scenarios of varying parameters such as flow, rheology and geometry of discharge area."

Jan 1, 2014

By Jihoe Kwon, Daeyang Lee, Mario Fujimura-Kashiwagui, Heechan Cho

"Calcium carbonate is one of the most widely used mineral in today's industries such as plastic, paper and pigment. There are many essential physicochemical properties required by each industry field but the most common requisite is size. One way to achieve appropriate size is grinding. Grinding is typically an energy intensive process, consuming about 40% of total energy cost in mineral process. Due to that reason, optimization of grinding process is a critical element to achieve price competitiveness. Two different type of grinding apparatus were hired to find out optimum condition in terms of energy efficiency. Utilizing samples containing 10, 20, 30 and 40% solids concentrations, a 1l batch type attrition mill was operated as the first grinding step at various operating speed with 1? to 5? grinding media in order to study the optimum operating conditions to reach submicron particles. Next, a 0.15l vertical beads mill was tested as next step with 100? to 500? grinding media to study the optimum conditions in the submicron range. Net energy and the specific energy input was measured to reach stated size ranges. Also, using a back-calculation based on the population balance model further operating conditions were studied. There were several competitive combinations which showed significant energy efficiency improvement when compared with the single step grinding."

Jan 1, 2014

By Deirdre Bradshaw, Cornelius Vos

"The detailed understanding of the variability in process performance parameters within an ore body forms a key aspect of ensuring that proper decisions are made with regards to the economic viability of that ore body. To gain this understanding, various tools have been developed over the years, of which the batch flotation test is the most well-known and applied technique for investigating the flotation separation of ores. In this paper, the Julius Kruttschnitt Mineral Separability Indicator (JKMSI) is put forward as a small-scale test, suitable for the characterization of the flotation separability of copper porphyry ores. It is demonstrated that the JKMSI can be a complementary technique to the batch flotation test, with the capability to further improve the knowledge of ore body variability. The response from this test has been shown to be sensitive to particle size and modal mineralogy, providing a critical link between flotation and upstream comminution activities. The trade-off between the fineness of grind and the recovery target can thus be evaluated to determine the minimum energy application required for optimal separation economics. The test is designed to utilize small sample quantities of various sizes, providing an opportunity to increase our understanding of ore variability through increased tests. This complements our ore body knowledge and combining this with efforts in comminution (Powell, 2013) provides a platform for extending the concept of flexible circuit design."

Jan 1, 2014

By Andries Van Wyk, Steven Bradshaw, Guven Akdogan, Jacques Eksteen, Cornelius Snyders, Cleophace Mpinga

"In order to exploit lower grade and complex platinum group metal resources, cheaper and more efficient alternatives to the conventional mill-float-smelt-refine route are being sought, particularly for resources’ in areas that are water-scarce and where electrification is costly and problematic. Leaching with cyanide is a promising process option and although recoveries are lower than in the conventional process routes, progress into the understanding of cyanide leaching of PGM containing ore and concentrate has been made. Research regarding the feasibility of upgrading the pregnant PGM leach solution using activated carbon has, however, been lacking and hence forms the focus of this paper. Bottle roll adsorption tests for dilute PGM solutions (0.15ppm Pt, 0.38 ppm Pd, 0.1 ppm Au) onto granular activated carbon showed high rates within the first 60 minutes (giving more than 90% recovery of precious metals). Comparison of the Pt isotherm to Au isotherms from literature indicated a similar loading capacity, while that of Pd was found to be significantly lower. The effects of solution pH, temperature, base metal concentration, free cyanide concentration, thiocyanate concentration, initial PGM concentration and activated carbon concentration were investigated and are discussed. Elution of the Pt and Pd, with the AARL elution process, was found to be effective with recoveries of 95% after 5 bed volumes of eluant at the optimum pre-treatment concentrations and a temperature of 80°C. Temperature, NaCN and NaOH pre-treatment concentration and the ionic strength of the eluant were found to be the most important factors affecting elution while base metals concentration, acid-pre-treatment, carbon loading and thiocyanate concentrations to a lesser extent. Simplified combined flow sheets are suggested and the corresponding mass balances are compared."

Jan 1, 2014

By Peter Scales, Ricardo Jeldres, Fernando Concha, Pedro Toledo, Shane Usher, Anthony Stickland

The impact of several electrolytes present in seawater on the rheological properties of flocculated mineral suspensions was assessed using the creep test. Flocculated suspensions were obtained by adding polymer flocculant to a cylinder of mineral suspension and aggregating the suspension using the plunger method. The suspension was allowed to sediment and the supernatant liquid decanted prior to tests for the viscoelastic properties of the resulting sediment. The solid used was alumina AKP-30 both, below and above the isoelectric point. The polymer used was AN934SH, an anionic flocculant with high molecular weight. Salts analyzed were MgCl2, CaCl2 and NaCl, known as water structure makers, and KI and KCl, known as water structure breakers. A high salt concentration of 0.5 M was used to approach the ionic strength of seawater. For both pH’s studied, the sediments demonstrated a viscoelastic non-linear behavior observed as a non-linear relationship between yield strain and applied stress. In the absence of flocculant, it was observed that the viscosity and yield stress of a suspension increase in the presence of structure maker salts for the case of both silica suspensions and alumina suspensions. These results were explained using hypernetted chain statistical mechanics models describing the interaction of ions with solvated surfaces. In contrast, with the presence of flocculant, the shear yield strain of alumina suspensions increases with the breaker character of the salts, however, this result has been explained by an extension of the results from the models. The work has significant implications for the flocculation of mineral suspensions in the presence of seawater.

Jan 1, 2014

By David I. Verrelli, Peter T. L. Koh

"Recent experimental measurements of induction time made by direct observation with the ‘Milli-Timer’ indicated that angular particles were able to attach much more rapidly than spherical particles. There was around a tenfold difference in the respective induction periods for particle-bubble attachment. For industrial application, a more holistic comparison is needed, with the induction period for attachment being just one input. Over the years, CSIRO has developed a CFD-flotation model that incorporates both rigorous hydrodynamics, to simulate real industrial cell geometries, and a detailed model of the embedded flotation process, in which the induction period is an important parameter. We conducted transient modelling of batch flotation. First, spherical particles were modelled, as a ‘baseline’, for different particle sizes and levels of hydrophobicity. In the second set of results, the induction period was decreased by a factor of up to ten, simulating flotation of angular particles. Flotation recovery was found to depend upon induction period in a complex manner. For highly hydrophobic or fine particles, the induction period for spheres was already so low that recovery was limited by other factors (e.g. bubble-particle collision frequency). Further decreases in induction period, as for angular particles, did not have a significant effect on recovery in these cases. By contrast, when weakly hydrophobic or coarse particles were modelled, the recovery was predicted to be greatly enhanced for angular particles, in comparison to spheres. For these particles the induction period was limiting recovery, so that the flotation rate constant could be improved directly by reducing the induction period. This is consistent with batch flotation experiments using Ballotini reported earlier. Therefore, when dealing with weakly hydrophobic particles or relatively large particles that are to be floated, an enhancement can be expected for more angular particle shapes. In such cases, judicious specification of the grinding circuit may improve the overall efficiency."

Jan 1, 2014

By Maurício Torem, Gabriela Huaman, Antonio Merma

The purpose of this review paper is to succinctly present the most significant works related to Mineral Processing and Environmental Bioremediation and developed by the Mineral and Environmental Technology Group (METG) of the Materials Engineering Department of the Pontifical Catholic University of Rio de Janeiro (PUC-Rio). In mineral processing it was emphasized the use of the Rhodococcus opacus bacteria as a bioreagent in the bioflotation of some mineral samples (magnesite, calcite, hematite, quartz and apatite). The adsorption of the bacterial cells on the mineral surface can be due to specific and/or non-specific interactions, which will depend on several factors, as their surface charge and hydrophobic character. The zeta potential evaluation of the mineral particles before and after interaction with the R. opacus cells showed that the biomass modified the zeta potential profiles of the minerals, which confirm the adsorption of bacterial cells on the mineral surface. Moreover, the bacterial cells adsorbed caused a change in the mineral flotability which is related to a change in their hydrophobic character, thus, the mineral bioflotability was found to be dependent on the pH and the bacterial concentration. On the other hand, the environmental bioremetiation assessed the biosorption potential of three metal ions (lead, copper, and cobalt) by four different biomass Streptomyces lunalinharesii, Rhodococcus opacus, Rhodococcus ruber and coconut shell powder. For this purpose, biosorption process was characterized under different operating conditions such as initial pH and biosorbent dosage. The Freundlich and Langmuir isotherm models were applied to the equilibrium data obtained at different concentration.

Jan 1, 2014

By V. A. Chanturiya

In Pt- and Au-keeping complex ores processing, about 10% ~ 15% of noble metals are lost with true tailings that are due to low floatability of Pt- and Au-keeping minerals by the conventional collectors. With the aim to achieve the effective recovery of noble metals at flotation of Pt-Cu-Ni and Au-keeping ores organic complex reagents keeping electron-donating atoms of nitrogen, oxygen, sulfur or phosphorus may be offered as selective collectors for the indicated minerals. These rea-gents tend to form complex compounds with PGM. Besides this, Cu-Ni-Pt and complex Pt and Au carbonated mica ores are characterized by finely disseminated (up to nanometer size) mineral forms of Pt in multivalent states. In this connection, the use of a combination of the strong ionic collectors with nonionic reactants that are capable to derivate complex compounds with multivalent PGM seems to be expedient for this type of ores. In the research new complex reactants were tested such as cyclic alkylene-trithiocarbonates, oxyalkyl butylxanthogen acid ethers, a combination of the collectors ? mercaptobenzothiazole (MBT) and dialkyldithiophosphates (DTP). Sorption and flotation tests were made with monomine-ralic samples of chalcopyrite, pentlandite, pyrrhotite, pyrite, and Pt-Cu-Ni sulfide ore samples. Sorption properties were examined by the extractive UV spectrophotometric method and potentiometric measurements. To indicate a structure of modified xanthate solutions the method of a thin-layer chromatography (TLC) was applied. The chromatographic behavior of the basic components of modified xanthate solution ? ButX, cyclic propylene-trithiocarbonate (PTTC), diethyl-dithiocarbamate (DEDC) and the product of its modification ? oxypropyl-S-ether of dithiocarbamatic acid was studied on plates ?Silufol UV ? 254?. The composition of organic solvents and its ratio in a mobile phase was deter-mined for simultaneous chromatography of the main components of a reaction mixture. It was found that operating selectivity of MBT, DTP and cyclic alkylene-trithiocarbonates incorporated in modified xanthate in relation to Pt-Cu-Ni and Au-containing sulfide minerals might be explained by an electoral sorption of this nonionic collector on a surface of the minerals studied. It was demonstrated that the application new reagent modes with the use of a combination of designed complex reactants helped to increase the extraction index of Pt- and Au-keeping minerals from complicated ores.

Jan 1, 2014

By F. Y. Kang

Graphite with layers structure is easily to form graphite intercalation compounds (GICs) by means of intercalation reactions due to the weak cohesion force among carbon layers, van der Waal?s interactions. By controlling the oxidation-intercalation, high quality exfoliated graphite with low residual sulfur content and MClx-GICs (M=Fe, Co, Ni, Cu, Zn) powder for electromagnetic wave absorbing and shielding materials have been invented. The expansion volume of expandable graphite can be larger than 160 mL/g while the residual sulfur content is less than 800 ppm. The MClx-GICs powder can shield infrared ray and laser completely up to 15 min. We have also in-vented exfoliated graphite for heavy oil adsorption and mild-expansion exfoliated graphite for anode materials in lithium ion battery by controlling the intercalation/de-intercalation. The exfoliated graphite can adsorb heavy oil up to 80 g/g, it also exhibits better performance than commercial active carbon in sewage treatment. The mild-expansion exfoliated graphite as anode material shows high capacity of 370 mAh/g and good cycle performance.

Jan 1, 2014

By C. H. Zhou

Cryogenic grinding of Printed Circuit Board will bring less pollution, reduce energy costs, smaller particles, regular particle size, efficient process, separation various materials due to different fracture toughness. Systemic studies of recycling discarded Printed Circuit Board (PCB) by low-temperature modification and cryogenic grinding have been made in this paper. Firstly test mechanical property of PCB at different low-temperature, including impact strength, flexural strength, and shear strength. Do experiment on the power consumption of different cooling temperature, The results show that the average power consumption is lower between -30? to -60? and the average power is decrease in evidence at -30?. Use ZKB type double roll shear crusher to crush PCB to 20mm×20mm particle size, in a temperature range of -10 ~ -30? Used R type mill to grind sample to minus 3mm under different working condition, the average power consumption is decrease in evidence from -10 ? to -30 ?, power consumption is the lest at rotational speed is 1180rpm.

Jan 1, 2014

By Tyler Acorn, Tristan Worsey

A dozer operator at a surface gold mine accidentally drove a D10 off the side of a highwall. The blade of the dozer caught on the lip of a catch bench 60 ft. (18.3 m), down stopping its descent. The operator scrambled to safety in fear that the dozer would not hold.

Jan 1, 2014

By C. Lemmer

The resolution with which the different categories of resources are forecast for Witwatersrand gold reefs should ideally tie in with block sizes that are optimal in terms of the variability structures of the reefs. A tool, called the ?variancegram?, is proposed as a basis for block size choice. A variancegram is intrinsic to the particular reef and mine concerned. A further requirement is the ability to attach global confidence limits to weighted average estimates built up from combinations of local kriged estimates. Approximations to derive global kriging variances based on variables derived from local kriging deliver hugely inflated results if ordinary kriging is used, and markedly better, but not accurate, values if simple kriging is used. These approximations improve as the number of samples used in kriging each block is increased. It is shown that the behaviour of the different components of the global kriging variance with increasing number of samples, all differs, but they all link to the variancegram for the particular reef. The variancegram can thus be used to correct the different components to the values they would have had if all samples were used in kriging each block, and so deliver the ?correct? global kriging variance, even though only a limited number of samples were used in kriging each block. The desirability of having very stable solutions implemented in production systems is taken into account in the proposals. It is anticipated that the same variancegram findings will also hold for other densely sampled deposits, but this remains to be investigated.

Jan 1, 2014

By J. Gotor, C. Frias, E. Delgado

The Iberian Pyrite Belt (IPB) is one of the world's largest reserves of primary sulphides containing base metals (Cu, Zn, Pb), precious metals and some special metals such as indium. Estimated resources are over 1,500 million tonnes of volcanogenic massive sulphide ores. From 1980´s Europe lives the decline in its mines mainly motivated by the low price of the metals. One aspect that contributed equally to this was the ecological disaster produced by the discharge of more than seven million tonnes from the tailings dam of Boliden-Apirsa (Aznalcollar) in 1998. Today the situation is different; the companies present in the IPB have given evidence that it is possible to reconcile mining projects and care on the environment, and the regional authorities are opening a public tender to re-start Aznalcollar mine. A new challenging era has been started at this Spanish/Portuguese mining area. This paper presents the results and preliminary economics of a project devoted to IPB primary sulphides processing through different technology approach, e.g. conventional selective flotation against bulk flotation or mixed metals flotation combined with hydrometallurgical processing.

Jan 1, 2014