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By S M. Gover

Estimating the probability of failure for embankments is not intuitive. It requires not only an appreciation of the strength of the embankment, but an understanding of the variability and uncertainty in the strength parameters as well. These additional aspects are, in themselves, relatively new to most practicing engineers, and therefore require some discussion.This paper discusses the concepts of probability and uncertainty, and presents a reliability-based numerical experiment, together with a literary study and collation of some of the author’s historical slope stability analyses, to investigate whether a direct relationship between safety factors and probabilities of failure exists for certain levels of uncertainty in strength parameters. In doing so, a useful tool is presented whereby knowing the safety factor of a simple slope or embankment with a consistent level of uncertainty, one can infer an approximate probability of failure.CITATION:Gover, S M, 2018. Linking safety factor to probability of failure, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 384–396 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By W Ludlow, C Harrington

This paper presents an overview of the design and construction challenges to implement capping systems on Tailings Storage Facility’s (TSF) based on recent projects in Australia. Key aspects discussed include the cover design and barrier system to encapsulate the tailings, designing for a service life of 1,000 years, water management considerations. construction on tailings, vegetation selection and agronomy of the available capping soils plus the Health, Safety and Enivornmental challenges faced in working on tailings. Lessons learned from experience in capping TSFs are also presented. CITATION:Ludlow, W and Harrington, C, 2018. Experience with Capping of Tailings Storage Facilities for Decommissioning Projects in Australia, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 157–165 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By Julio Cesar Tremolada

La lixiviación con tiosulfato de amonio (ATS) puede ser considerada como una alternativa ecológica viable para lixiviar metales preciosos, por comparación con la alta toxicidad del proceso convencional de cianuración, especialmente en el caso de algunos minerales refractarios con presencia de impurezas que provocan baja recuperación de oro y altos consumos de cianuro. En este estudio se evaluó un mineral aurífero asociado a carbón para confirmar los óptimos resultados de la tecnología innovadora ATS, cuyos principales compuestos son amonio tiosulfato, sulfato de amonio, ion cúprico y metabisulfito. De acuerdo con el estudio reseñado en este artículo, la concentración cuprífera a un ratio de 0.5 Kg/Tm proporciona una óptima extracción de oro de 75.20% con 8.60 Kg/Tm de ratio de consumo de tiosulfato (escala de tratamiento: 10,000 Tm en pads de lixiviación a granulometría de 90% <2.5 pulgadas, en 45 días de lixiviación); y extracción de oro de 81.20% con 6.5 Kg/Tm de consumo de tiosulfato en mineral aurífero limpio y de características dóciles (escala de tratamiento: 20,000 Tm en pilas de lixiviación en similares tamaños granulométrico y tiempo de lixiviación). En tanques agitadores, las extracciones de oro son del orden de 90.75% en minerales refractarios (en 120 horas de lixiviación a granulometría de 80% <325 mallas), con ratio de tiosulfato de 7.4 Kg/Tm; y en minerales limpios/dóciles las extracciones de oro alcanzan 93.6% (en 120 horas de tratamiento a granulometría de 80% <325 mallas), con ratio de tiosulfato de 6.3 Kg /Tm. En cambio, la lixiviación convencional con cianuro en este tipo de minerales refractarios no supera al 10% de la recuperación metalúrgica del oro.

May 30, 2018

By Jorge Cangahuala

La neurociencia ha cobrado un papel muy importante en las organizaciones en las últimas décadas. En ese contexto, la neuroprevención busca determinar las potencialidades y limitaciones del cerebro al momento de enfrentar situaciones con potencial de algún incidente o accidente laboral. Identificando estos indicadores y conexiones neuro-centrales podemos tener mapeado cómo se comporta nuestro cerebro, cómo lo refleja en el comportamiento (acto seguro o inseguro) y cuáles técnicas implementar en cada proceso, para asegurar una cultura de seguridad preventiva y sostenible en el tiempo que se orienta primero al factor humano como generador de conductas que pueden ser remodeladas hacia acciones seguras.

Apr 30, 2018

By Gustavo De la Torre

Más allá de contar con las certificaciones ISO 9001, ISO 14001, Y OHSAS 18001, la planta concentradora de Cerro Lindo busca ser catalogada como un desempeño de categoría mundial, lo que implica usar la capacidad total del área (procesos, tecnología y talento humano) basado en un equipo de alta performance-EAR, y gestionar de forma sistemática seguridad, salud ocupacional, medio ambiente, costos, productividad, calidad y confiabilidad, además del proceso productivo. En el presente artículo se analiza información recopilada durante la fase de crecimiento, se presentan diferentes etapas en desarrollo y se describen los estudios realizados en la planta de beneficio, a nivel técnico y de gestión, con óptimos resultados de producción, eficiencia e indicadores metalúrgicos.

Apr 30, 2018

By Xueqin Li, Xuewei Lv, Yu Zhang, Wenchao He

In order to make full use of the chromium-bearing vanadium titanium magnetite with chromium, a new process of “direct reduction-electric furnace smelting separation” has been developed for recovering the iron, vanadium, titanium and chromium in recent years. In this paper, FactSage, one of the most frequently-used thermodynamic calculation software, was used to calculate the reduction degree of Fe, V and Cr with different n C/nO (mole ratio of carbon and oxygen). It was found that the suitable operating conditions of direct reduction process were n C/nO > 1.07 and T > 1473 K. In addition, the direct reduction experiment of Hongge vanadium titanium magnetite was carried out and the obtained samples after direct reduction were analyzed by XRD and chemical composition. The result shows that the metallization rate of carbon-containing pellet is nearly 90%.

Mar 1, 2018

By Kun Wang, Weipeng Luan, Qingbo Yu, Qin Qin

The oxygen uncoupling property of the oxygen carrier is essential for the chemical looping gasification process. In this paper,the combined Cu-based oxygen carrier were prepared by mechanical mixing method. XRD and SEM were used to characterize the oxygen carrier prepared. TG experiments were performed in a thermal analyzer to investigate the oxygen uncoupling property. The XRD pattern of the fresh oxygen carriers showed that the phases of the oxygen carriers were stable.The active phase of oxygen carrier was CuMnO. With the increasing of x 3-x 4 heating rate, the starting and ending temperatures of the reduction reaction increased. However, the reaction time decreased and the reduction rate increased. With the increasing of oxygen concentration, the starting temperatures of the reduction reaction shifted to high level. Temperature had great effect on the reduction rate and the reduction rate increased with increasing of the reduction temperatures.

Mar 1, 2018

By Ahmad Ghahreman, James McNeice

Separation of rare earth elements (REE) is often achieved by acid leaching of mineral concentrates followed by subsequent solvent extraction (SX), to purify individual rare earth metals (REM). Cerium, the most abundant REE, is usually the largest component of these ores. Demand for less prevalent REE, such as praseodymium and dysprosium; have led to a market saturation and price collapse of cerium. One method of improving the economics of REE separation is to remove cerium from solution prior to SX. This is accomplished via the oxidation of cerium (III) to cerium (IV), which precipitates as cerium hydroxides. This study probes the efficacy of four oxidants; hydrogen peroxide, sodium hypochlorite, potassium permanganate, and Caro’s Acid with the goal of improving cerium removal whilst minimizing REE and reagent losses. The effect of oxidant type and dosage, pH, cerium concentration, and temperature on the kinetics of the process will be discussed.

Mar 1, 2018

By Pamela Bogust, York R. Smith

Photovoltaic (PV) modules are becoming an ever increasingly larger part of our energy portfolio. As more and more PV modules are installed and come on-line, management of end-of-life (EOL) modules becomes an important issue. Currently, management of overburden EOL PV modules is not an issue, but is anticipated to be by 2030. Recovery and recycling of valuable metals in PV modules presents several environmental and economic advantages. In this brief review, we will describe processes for refurbishing and recycling of PV silicon. These processes involve some combination of mechanical, thermal, and chemical processing, all of which all have their oPV) modules have become wn respective challenges. Also, projections of PV module material streams are also highlighted.

Mar 1, 2018

By Mairyanne S. S. Souza, Sergio Neves Monteiro, Victor Tomazinho Bartolazzi, Dienifer Daiana Konzen

Clay is used in the production and manufacture of materials for the construction of buildings from remote periods. Advances and improvements of its properties have allowed several applications to this raw material. In this work the quality of four types of ceramic tiles manufactured or used in the northwest of the state of Rio de Janeiro and in the southeastern state of Minas Gerais was evaluated. Geometric, physical and mechanical aspects were evaluated according to the Brazilian standard NBR 15310:2009. The results indicate numerous nonconfor- mities with highlights for geometric parameters, surface flatness and yield tests. The nonconformities found in the samples indicate that there was a failure in the production control of the product and in the approval of the control of the lots.

Mar 1, 2018

By Ozgul Keles, Dila Sivlin

Lithium ion batteries are potential energy source of next generation electric vehicles (EVs). However, some problems such as safety, durability, low capacity, cycle life etc. restrict their use in EVs. These problems mostly related with cathode materials, an improvement in cathode materials may cause significant changes in battery performance. In this work, to overcome cycle life problem Al2O3 coating on LiNi0.5Mn0.3Co0.2O2 cathode material produced by sol-gel method. The surface modification of LiNi0.5Mn0.3Co0,2O2 was started by adding LiNi0.5Mn0.3Co0.2O2 powders into alumina sol. Then, sonication was started and two different sonication powers were tested (45, 100%). After the second gel is obtained, last heat treatment for Al2O3 crystallization was done at 600 °C for 4 h. X-ray diffraction (XRD) measurements showed that the material had a well-ordered layered structure and Al was not in the LiNi0.5Mn0.3Co0.2O2. Al2O3 coated materials show better cycling performance compared to the pristine material. It is believed that, this improvement is caused by the fact that Al2O3 layer prevents direct contact between active material and electrolyte and reducing decomposition reactions.

Mar 1, 2018

By Feng Wang, Guojing Shi, Yangyang Xie, Zizong Zhu, Qiang Wu

The coal chars from northwestern part of China are characterized with high reactivity and low strength after reaction. Four type of coke-making coals selected from northwestern part of China were studied by proximate analysis, ultimate analysis, vitrinite reflectance analysis, and FTIR with curve-fitting analysis to obtain information on their chemical composition and chemical structure. The results show that the studied coals have relatively high values of final contraction of coke residue index (x) and relatively low values of maximum thickness of plastic layer (y) and average vitrinite reflectance. Based on the curve-fitting analysis of FTIR spectra, the aliphatic carbon (Cal), the aromatic carbon (Car), and the molecular structural parameters such as CH2/CH3, fa, Hal/Har, and (R/C)u are determined. The results of curve-fitting analysis indicate that the studied coals are characterized by a large amount of oxygen-containing functional groups and aliphatic side chains.

Mar 1, 2018

By Shengli Wu, Yuandong Pei, Shaoguo Chen, Zhixing Zhao, Haijun Kang, Jiangshan Shi, Wen Pan, Zhengming Cheng, Yaosheng Luo

Grate bar is the key component of the sinter machine used for loading sinter and raw materials. Bar channels are sometimes bonded into blocks, which affects the service life of bar, and more importantly reduces the effective ventilation area of the sintering, affecting the normal production of sintering, resulting in unstable negative pressure, higher electricity consumption, and lower production and quality of sinter. In order to solve this problem, the systematic study was done on bonding materials of bars, based on which bonding mechanism of sinter grate bars was obtained. The KCl is an important characterization of bonding. Control standard of blending ore that prevents bonding is K2O content below 0.06% and Cl content below 0.05%.

Mar 1, 2018

By Qiang Guo, Zongliang Zuo, Mengqi Wei, Qingbo Yu, Qin Qin

Activated carbons, derived from waste ion-exchange resin by CO2 physical activation, were applied to separate CO2 from flue gas against global warming. The BET specific surface areas of activated carbons at different activation temperatures and times were investigated. The CO2 adsorption capacity was tested under non-isothermal and isothermal conditions. The experimental results show that when keeping the activation temperature constant, the specific surface area increases firstly and then decreases with increasing activation time. For the given activation time, the specific surface area rises firstly and then declines with increasing activation temperature. The adsorption capacity decreases with increasing temperature. The maximum adsorption capacity is 51.46 mg/g under the condition of 298 K and pure CO2. Fractional order kinetic model is the best one to describe the kinetics of CO2 adsorption. The activated carbons show the potential to be an effective adsorbent for the removal of CO2 from flue gas.

Mar 1, 2018

By Leizhang Gao, Zhengfeng Qu, Pingsheng Lai, Chenguang Bai, Meilong Hu

FFC process could be used to prepare titanium foams. The mixed oxides CaO-TiO2 with mole ratio 1:2 were sintered into CaTiO3-TiO2 mixture. CaTiO3-TiO2 was then used as cathode and electrolyzed in molten CaCl2 to prepare porous titanium. The porous titanium with the porosity of about 72.15% was first fabricated. The internal pores are in the presence of circular cavities and the pore size is in the range of 50–100 lm. Compared with the powder metallurgy technique using the space-holder this method promises to be lower cost and less processing. It is potential to fabricate titanium foams using FFC process.

Mar 1, 2018

By Mohammad Mokmeli, Colin Oloman, Rod McElroy, William McWilliam, Bruce Downing, David Trueman, David Dreisinger

Lithium is anticipated to be a key, strategic material in the clean tech- nology economy. The majority of lithium reserves are contained in continental brines and sea water (>60%). Currently the most economical approach to recover lithium from such resources is through selective adsorption. Spinel type lithium manganese oxide and lithium titanium oxide have demonstrated to be excellent candidate materials (after de-lithiation). However, due to the small size of the powders, they have limited industrial application and require immobilization. In this work, we examine the application of novel manganese oxide nanowire composites for the extraction of lithium from dilute solutions. Manganese oxide nanowires were synthesized and simultaneously immobilized on diatomaceous earth via hydrothermal method. Lithium manganese oxide were then formed by solid-state reaction, de-lithiated and tested for lithium ion adsorption.

Mar 1, 2018

By Timothy W. Ellis, John A. Howes, Roger D. Feldman

The new generation of more powerful, energy-intensive devices for communications, industrial production, energy storage and other purposes is creating new challenges to guard against environmental harm and protect national security. Many devices are designed, used and disposed of in a linear, rather than circular manner. This causes scientific, legal and economic issues because the life-cycle costs of components are not adequately considered. Dealing with these issues in isolation from each other can lead to unintended consequences. New models to confront these issues are being defined. This paper suggests a fundamental tool for dealing with material science issues while taking into account the engineering, economic and policy perspectives. That tool is the development of a true, levelized cost of energy storage model with a wide spectrum of inputs for comprehensive analysis. This paper will discuss inputs and the process which can yield meaningful, useful comparisons among batteries and energy-intensive products.

Mar 1, 2018

By James C. Withers

There is no production of rare earth metals in the U.S. in spite that the U.S. is the largest consumer of rare earths in some form that includes consumer and Department of Defense (DoD) devices. The one U.S. mine has been purchased by the Chinese that even enhances their monopoly on rare earths. A research effort has demonstrated rare earth oxides can be extracted from bastnaesite ore as well as coal ash at efficiencies in the upper 90s percent. The rare earth oxide can be carbothermically treated to produce an oxycarbide which is highly electrically conductive. The rare earth oxycarbide can be used as an anode in anhydrous fused salts electrolysis to produce a highly purified rare earth powdered metal. It is also possible to electrofractionate the individual metals which can be combined with co-deposition of iron and boron to produce the highly magnetic alloy Nd2Fe14B.

Mar 1, 2018

By Kevin Trumble, David Johnson, Kyungjean Min

The electrolytic manganese dioxide (EMD) production through electrodeposition from manganese nodules by reduction leaching in H2SO4 medium using sucrose as reductant followed by purification through 2-stage precipitation methods is described. The purified leach liquor was the starting solution for electrodeposition. Influence of in situ addition of a cationic surfactant Cetyltri-methylammonium bromide (CTAB) (0–500 mg dm −3) on the surface morphology and electrochemical properties of the EMD was examined. The XRD patterns of the deposited material were indexed to the c-MnO2 phase. FESEM results demonstrated that in the presence of CTAB uniform nanofibrous type grains were formed. Higher concentration of CTAB in the electrolytic bath however, drastically decreased the current efficiency (CE) and increased the energy consumption (EC) during electrodeposition. Under the optimum CTAB concentration of 100 mg dm −3 the obtained CE and EC values were 87.64% and 1.70 kWh/Kg respectively.

Mar 1, 2018

By Ming Li, Li Ma, Yunqing Tian, Haoyu Cai, Luyao Zhao, Wenwang Liu, Wenbin Huang, Gele Qing, Yan Zhang

In this paper, study on the in fluences of different Ti-bearing materials on MgO-bearing pellets metallurgical properties was carried out. The results show that, pellets compression strength will decrease while using ilmenite. However, TiO2 reagents help to improve pellets compression strength. The reduction swelling decreases while using TiO2 reagents, but different ilmenites have diverse impacts on the reduction swelling. Pellets compression strength will decrease and reduction swelling will be improved while adding magnesium additives. In order to produce qualified Magnesium-Titanium bearing pellets, the firing temperature should be no less than 1270 °C.

Mar 1, 2018