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By Francoi Robert, Andre J. Audet, Alex C. Brown

"The Sigma gold deposit is in a band of deformed metavolcanic rocks that are cut by an irregular mass of porphyritic diorite and by narrow undeformed feldspar porphyry dykes. The gold is in veins consisting mainly of quartz and tourmaline with minor pyrite, carbonate, chlorite, scheelite and free gold. The results presented here concern the structural setting of the ore and are based on a study of the mode of emplacement.Two principal types of veins have been recognized: subvertical and oblique veins. Both types are contemporaneous, mechanically linked and postdate regional deformation. The sub-vertical veins are composed of numerous mineralized lenses that occupy the central part of ductile shear zones of great lateral and vertical extent. Normally, several lenses occur in the same shear zone. The vein material seems to have resulted from incremental filling of openings by repeated vertical movement along rupture planes developed in the central part of the shear zones.The oblique veins are small elliptical lenses of ribboned vein material which formed essentially by progressive vertical opening of oblique fractures. Two types of oblique veins are known: one is restricted to feldspar porphyry dykes, within which they are arranged in an en-echelon fashion; the other is of greater extent and is not restricted to one rock type, but tends, however, to occur in the more competent porphyritic diorite.Vein orientation and mode of formation suggest that both sub-vertical and oblique veins developed during progressive deformation associated with the formation of the ductile shear zones. The latter probably formed in response to a compression that took place late in the tectonic history of the host rocks at Sigma."

Jan 1, 1983

By J. Dufour

Although the recovery of nitric and hydrofluoric acids from stainless steel pickle liquors has been solved by several methods, such as solvent extraction, acid retardation, evaporation or pyrohydrolysis, metals (mainly iron, chromium and nickel) are usually obtained as a waste or by-product that has to be disposed. Alternatively, the treatment requires a high liquor flow to be economical, as is the case for pyrohydrolysis. A new process has been developed for metals recovery, that produces metal oxides with a low fluoride content. This new technique is based on a selective precipitation mechanism, which produces nickel hydroxide with a purity of 90%, separate from a mixture of iron and chromium oxides and hydroxides suitable for recycling. The reaction mechanism is based on the precipitation of fluoride compounds of iron and chromium, K2FeF5 and CrF3. For this purpose, free fluoride must be added as potassium fluoride. Also, solid fluoride compounds are hydrolysed, releasing free fluoride. A part of the fluoride is recycled to the selective precipitation operation and the remainder is fed to the acid recovery stage. Nickel does not react in this operation; it remains in solution giving a high separation yield.

Jan 1, 2006

By K. K. Panthi, P. K. Shrestha

"Displacement of rock mass around a tunnel opening varies according to the rock mass properties, insitu stress conditions and applied support in the tunnel. Such displacement is also altered by presence of bands of rock mass that differ in properties. This paper focuses on the deformation behavior of rock mass around tunnel openings at four tunnel sections in Kaligandaki headrace tunnel where extensive instrumentation was done. Based on the actually measured tunnel displacement records and actually measured support pressure; back analysis has been done to estimate rock mass properties and insitu stresses. Numerical analysis has been done to analyze and assess the deformation behavior of the rock mass around the tunnel sections.INTRODUCTION Instrumentation and monitoring of tunnel convergences have significant importance in evaluation of tunnel stability. One of the key aspects of monitored data is that early convergences can be used in estimation of long term convergence. In addition, these data can also be used in evaluation of rock mass parameters and in-situ stresses around the tunnel. Convergence around a tunnel periphery may vary according to rock mass quality. Presence of bands of different rock mass may hinder the displacement pattern in the tunnel. Particularly, displacement characteristic of tunnel periphery in schistose, foliated and deformed rock mass is altered by presence of bands of comparatively stronger rock mass, e.g., quartz veins or presence of shear seams or faults. Similar observations were also recorded in monitored tunnel sections in Kaligandaki headrace tunnel, located in the Nepal Himalayas. Extensive monitoring was done by installing multiple point borehole extensometers (MPBX) at three different locations of the tunnel periphery at four different tunnel sections. In addition, convergence measurements by tape extensometers and installation of pressure cells to record support pressures were also carried out at each of the tunnel sections. Observations showed that the tunnel convergences varied according to rock mass quality, in-situ stress and effective support pressure.Rock mass parameters and stresses have significant role in the extent of tunnel deformation, but these parameters are often unknown or difficult to predict. Back analysis based on actual tunnel displacement records and known support pressure is believed to be an important method in such endeavor. This paper performs back analysis to evaluate rock mass parameters and discusses correlation of rock mass behavior with tunnel deformation and applied support. For this purpose, the rock mass parameters are estimated from actual tunnel displacement records, mapped rock mass quality records and laboratory tested data. Then, numerical modelling is conducted to correlate post peak behavior of the rock mass with actual tunnel displacement."

Jan 1, 2015

By D. R. Boyle

"The basal type uranium deposits in south central British Columbia occur within unconsolidated, late Miocene fluvial paleochannel sediments that overlie major fault zones within the Okanagan Highlands Intrusive Complex. Prior to the formation of mineralization, paleovalleys containing host sediments were flooded by Pliocene valley basalts of the Plateau Basalt Formation. Five uranium deposits have been outlined to date, of which the Blizzard (4020 tonnes U) and TYee (650 tonnes U) are the largest. The basement intrusive complex underlying the deposits varies in age from early Cretaceous to Eocene and is comprised of quartz monzonite, granodiorite, Coryell monzonite, porphyritic granite and pegmatite.The mineralized host sediments comprise a complex sequence of interfingering conglomerates, arkosic sandstones and mudstones. Organic material is abundant in many, but not all, mineralized beds. Uranium mineralization is present in the form of uranous (ningyoite) or uranyl (saleeite, autunite) phosphates coating clastic grains and filling voids. Because of very strong reducing conditions related to large concentrations of marcasite and organic material, ningyoite is the only uranium mineral in the Tyee deposit, whereas the Blizzard deposit contains a more complex assemblage of minerals (saleeite, autunite, ningyoite). The observed paragenetic sequence of mineral precipitation in the Blizzard deposit (autunite-saleeite-ningyoite) indicates that the uranyl minerals, saleeite and autunite, are primary. Small amounts of Zn, Ni, Co and Mo have been introduced into the Blizzard deposit whereas Mo is the only non ore-forming element enriched in the Tyee deposit. Mn is the only depleted element in both deposits."

Jan 1, 1986

By T Nakamura, M. Itoh

Most of the used cathode ray tube (CRT) glass in Japan, which contains lead oxide, was exported and recycled in overseas factories of new CRTs. However, domestic treatment and recycling of waste CRT glass has become necessary because overseas CRT factories have shut down and exports of CRT glass have stopped. Some of the waste CRT glass recycled domestically is charged in lead blast furnaces instead of silica flux, because there is no local reproduction route for glass that contains lead. However, the mass of CRT glass that can be treated in this manner is limited because of its high silica content. Consequently, additional treatment methods for waste CRT glass are required so that more can be used as a lead smelting material. In this study, waste CRT glass was treated with hydrofluoric acid to dissolve the silica contained in the glass, and the dissolved lead was recovered by precipitation. Lead metal was recovered by electrodeposition from the prepared hexafluorosilicic acid solution.

Jan 1, 2011

By O. Engler, J. Friis, S. J. Andersen, C. D. Marioara, Y. Aruga

"This work investigates the early stages of precipitation in Al-Mg-Si alloys using a combination of high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), selected area electron diffraction (SAED) and density functional theory (DFT) calculations. Quenching from a high temperature (solution) treatment leaves an alloy in a high-energy unstable state, with solute and vacancies in supersaturation. Thus, already at room temperature (RT) a large driving force exists for solute atoms to cluster and order on the Al matrix positions. DFT calculations indicate that strain alleviation is important at this stage. We observe larger regions of Mg-dominated L10 ordering together with a Si-dominated ordering of smaller clusters in a particular geometry connected to the Si-network found in all the precipitates. In addition, building blocks of the main hardening phase ?'', stabilized by vacancies, are observed at higher, typical pre-aging temperatures.INTRODUCTION Al-Mg-Si (6xxx) alloys are widely used in industry due to a combination of favorable properties such as strength, ductility, corrosion resistance and lightweight. They undergo a complex production route, usually consisting of the following thermo-mechanical steps: casting, homogenization, extrusion or rolling, solution heat treatment (SHT) and artificial aging (AA). The SHT takes place at temperatures above the solvus line in the phase diagram, usually between 500°C and 570°C, followed by a rapid cooling to RT. This ensures that high amounts of solute atoms, uniformly distributed on the cubic face-centered (FCC) Al lattice, together with a large amount of vacancies, are quenched-in. The material is therefore in a super-saturated and unstable state. During the subsequent AA, at temperatures usually between 150°C and 220°C, the solute atoms diffuse and cluster, forming metastable precipitates with needle/ lath/ rod morphologies having the main growth direction along <100>Al. With a maximum alloy solute level (Mg + Si) of only 2%, these precipitates increase material strength up to three times that of pure Al, and are essential for the final material properties. To understand and make better use of this phenomenon, it is imperative to research the nature of the precipitates (such as their atomic structure), measure their key parameters (number density, size, volume fraction) and connect it to material properties (Marioara, Andersen, Zandbergen & Holmestad, 2005; Marioara et al., 2014). The following precipitation sequence is given for the Al-Mg-Si system:"

Jan 1, 2018

By I. Raheb, M. Y. Debili

"A set of Al-Co binary alloys (with respectively in weight percent 10%, 20%, 30%, 40%, 50% and 60% Co) have been studied by X-ray diffraction at the as compacted state. The structural evolution according to cobalt addition shows special features as the apparition of fcc cobalt and hcp cobalt beside aluminium in some cobalt compositions of the Al-Co mixtures using only cold compaction without sintering at high temperature. Figure 1 Cobalt is not a common alloying element in aluminium because its solubility is very low [1]. According to the pressure-temperature phase diagram, Co is known to exist in two allotropic forms: a low-temperature hcp phase and a high-temperature fcc phase [2-3]. At room temperature, Co is stable in the hcp form but it transforms to the fcc form when it is heated to above the transition temperature 695K. Powder aluminium and cobalt (99.999 %) were used in the proportions defined according to the required compositions. The total mass of the samples to be elaborated was between 8 g and 10 g. Cold compaction of mixed powder (Al-Co) under an uniaxial load of 10 MPa has been achieved to obtain a dense product (60%)."

Jan 1, 2015

By Ben C. McLellan, Philip J. Bangerter, Andrew Murphy, Glen D. Corder, Damien Giurco

Sustainability now forms a critical part of metallurgical plant design. In addition to compliance with requirements and corporate principles, design engineers must also consider how community and societal responses to the metallurgical industry affect the way they design and build plants. Three broad areas to consider are: the design engineer’s contribution to sustainability through the design process and the relationship to the social license to operate (SLO)—the unwritten license communities give companies to safely and responsibly operate the plant and equitably share benefits; the realization of sustainability goals through methodologies emerging in the design activities; and the integration of design frameworks into a contemporary project design context and its investment objectives. This chapter explores sustainability in metallurgical plant design in the context of SLO, design tools and frameworks, and community and societal influences.

Jan 1, 2015

By J. P. Piguet, A. Hosni, J. P. Josien, H. Baroudi, R. Hadadou

"The iron ore mines in the Lorraine region of north-eastern France cover a surface area of approximately 3,900 km2 and involve more than 150 cities. A total extraction method was usually used during exploitation, but this technique was sometimes replaced by the room and abandoned pillar technique when it was necessary to protect surface buildings and infrastructure. Rooms and abandoned pillars were initially designed to ensure long-term mine stability. However, this aim was not always reached and numerous collapses occurred in the Lorraine iron basin, either during production or several years after closure. Several subsidence events were identified during a period of one century; the most recent event occurred in 2012. Two groups of events were identified. The first group represents events characterized by sudden surface movement, and the second group includes event characterized by progressive subsidence.Numerous studies conducted during the last decade helped improve our understanding the origin mechanism of spontaneous or progressive (slow) events. These studies led to identifying long-term potentially unstable underground zones (hazard zones), particularly deep zones located under buildings and infrastructure. The latest are currently monitored by microseismic networks. A similar high requirement level is needed for unstable zones without taking into account the kinetics of the subsidence, which is very important for safety. Thus, GEODERIS initiated this study, primarily to acquire a better understanding of the kinetics of the progressive events group and identify the main parameters that could explain why some pillars zones developed a maximum amplitude subsidence on surface within a few hours or days, while it took several weeks to months for others. In practice, the results of this study will facilitate adapting the requirement level of microseismic monitoring system to the kinetics of pillar collapse.To retrieve the real kinetics for each event, historical and sparse documentation was used. Firstly, archives research was conducted, especially testimonies and newspaper articles published during the events. This work helped to gather useful information that sometimes contained a precise description of subsidence duration. The archives research helped to classify some progressive events according to the subsidence kinetics. Secondly, a diagnostic of geotechnical and geomechanical parameters of historic events was realized, combined with a cross analysis of the data. The analysis took into account dimensions of underground workings (e.g., pillar lengths, widths, heights, introduction of a “pillar shape factor”, and stress amount). An original expression was highlighted to connect the pillar geometry to the stress state. The kinetics expression was calibrated to classify the historic events taken into account according to the kinetics of movements. The kinetic criterion was applied to predict subsidence kinetics for the potential unstable zones currently monitored by a microseismic system."

Jan 1, 2015

By B. Yamamoto, D. Post, J. De Leon, A. Meike

"This paper describes the theory, design, building, and testing of the passive magnetic bearing stabilizing system which is the core of the passive magnetic bearing system. The stabilizing system is made up of two large magnetic disks opposing themselves with a stabilizing disk in the center which allows the system to self-locate in a null position without the need for external power sources or sensors. When outside forces act upon the stabilizer, the magnetic fields interact with the stabilizing plate to return the system to its null position. Collaboration between two industry leaders has allowed an actual prototype to be built and tested providing real data to prove out the theory.INTRODUCTIONMagnetic bearing/stabilizer systems have many advantages over conventional mechanical bearing systems. These include near-zero drag losses and no need for lubrication since the rotating elements make no mechanical contact with the stationary elements of the bearing system. However all magnetic bearing systems must contend with a constraint known as Earnshaw’s Theorem in the early 1800’s, this theorem asserts the impossibility of constructing a stable, non-contacting, electrostatic or magnetostatic levitation system using only fixed charges or fixed magnetic poles, such as those produced by permanent magnets. Because of the constraint imposed by Earnshaw’s Theorem virtually all present-day commercial magnetic bearing systems are of the “active” type. That is, they employ electromagnets that are powered by amplifiers the inputs to which come from sensors embedded in the bearing system. These sensors are a part of a feedback loop that operates to keep the levitated rotating parts of the bearing stable and centered. The resulting complexity means that active magnetic bearings are expensive, require periodic maintenance, and continuously consume electrical power to energize their amplifiers and their electromagnets.Passive magnetic bearings are, of course, also subject to the constraints imposed by Earnshaw’s Theorem but they solve this problem in a straightforward and simple way, with only “passive” elements that take advantage of a loophole implicit in the derivation of Earnshaw’s Theorem. This loophole is that Earnshaw’s Theorem as derived applies only to static systems, i.e. an assembly of stationary permanent magnets arranged so as to levitate an object containing other permanent magnets. The theorem can be overcome if dynamic effects are taken into account. In active magnetic bearings the “dynamic effects” involve the afore-mentioned sensors, amplifiers, and electromagnets."

Jan 1, 2012

By Sabine Noelte, Mikko Petteri Rantamäki, Christopher Robben, Anssi Takala, Karl-Erik Rånman

"Sensor-based ore sorting is on its way to establish as a standard option for physical separation. The increasing number of installations in coal, iron ore, industrial minerals and hard-rock metal mining segments underlines the technological and financial potential that is beginning to be untapped. The Ma’aden Phosphate installation with 1.650 t/h sensor-based ore sorter feed sets a new benchmark for the possible capacity of stationary installations. Besides stationary installations, including multiple sorters parallel in different size ranges and multiple stages, containerised semi-mobile plants are applied. These offer two advantages, first being the reduction of transport costs when applied close to the mining face. The second is that semi-mobile systems enable processing of tens of thousands of tonnes of ore in a piloting phase with an approximate duration of 0.5 to six months, verifying the results laboratory mini-bulk tests on 5–10 tonnes of sample. This is especially important for low-grade metal ores because of the inherent Fundamental Sampling Error, as well as the Grouping and Segregation Error. The paper elaborates the results achieved within the I2MINE project, treating polymetallic ore at the Boliden Concentrator in Sweden.INTRODUCTIONSensor-based ore sorting (SBS) is becoming a standard option for physical separation, applied in all segments of mineral production. The Umm Wu’al project sets the bar for stationary SBS installations with 1,650 t/h feed (TOMRA, 2015). TOMRA Sorting Solutions has finalised an agreement in cooperation with Outotec to supply Outotec-branded sorting solutions for the mining and metallurgical industry (TOMRA, 2014). Especially for low-grade hard rock metal ores, an interdisciplinary approach is necessary applying experts for all aspects of mineral production. Due to the impact on the whole process stream, it is important on the end user side to have high level managerial support and involve all disciplines to ensure that all stake holders are involved in the analysis."

Jan 1, 2016

By A. Gauthier, J .. E. Muir, M. Cormier

Falconbridge's Lac Shortt gold deposit is located in Gand Township, some 25 km north-east of Desmaraisville, The deposit was outlined in i980 by a drilling program me conducted by Falconbridge Ltd. in a joint venture with Corporation Falconbridge Copper after three years of systematic exploration by Falconbridge Ltd. in the Desmaraisville area. The gold bearing structure had previously been drilled by three other exploration companies. As based on an underground development programme conducted by Corporation Falconbridge Copper, the "in-si tu" mineral inventory to a depth of 500 metres at a cut-off grade of 3.0 g/t is estimated at 1 937 605 tonnes at a grade of 6.4 g/t (uncut) and 6.0 g/t (cut). Regionally, the stratigraphy consists of thick sequences of volcanic and volcanosedimentary rocks intruded by numerous and voluminous mafic (gabbro), felsic (granodiorite, syenite) and anorthositic intrusions. Structurally, at least two fold sets and one major fault system (E-NE) are present. Minor fault systems oriented E-NE and N-NW also occur. Mine stratigraphy can be divided into 1) - the hangingwall; 2) - ore zone; 3) - footwall. Hanging wall rocks include: a) green lapilli and blocky tuff b) transition zone c) green mica crystal tuff and d) red dolomitic tuff. Ore zone rocks include: a) bleached mafic tuff b) barren carbonates, c) pyritic dolomitic tuff (?) and d) brick-red syenite. Footwall rocks include: a) magnetic lava (so-called diorite), b) mafic lapilli and blocky tuff and c) alkali basalt, Native gold is the only gold mineral so far identified and it occurs both as free grains in gangue and as micro-inclusions in pyrite. Two geochemical groups were identified in the main rock units: 1) Alkali-rich rocks cons is ting of the ore zone and foot wall rocks and 2) Subalkaline group consisting of the hanging wall rocks. Ore analysis also shows Ba, Sr, W, Zr, REE and F enrichment in the ore zone. Footwall rocks are enriched in Na20. Present geological and geochemical data do not permit a clear interpretation of the formation for the Lac Shortt gold deposit but suggest it is a volcanic-hosted stratabound type. The bulk of the mineralization is associated with an exhalative phase following alkalic, carbonic, hydrothermal activity and part of the mineralization is associated with a late intrusive phase.

Jan 1, 1984

By J. Karonen, M. Tiihonen, J. Guentner, L. Haavanlammi, Outotec GmbH, E. Kolehmainen

"Rare earth elements have obtained significant attention during the last few years due to predicted increase in their demand. Several projects worldwide are at pre-feasibility or feasibility stage aiming to commence production. Deposits of rare earth elements are typically complex and multi-metallic of nature. This means that production processes are often also complex and therefore, various metallurgical unit processes are needed. Outotec’s equipment and technology portfolio is very comprehensive and includes hydrometallurgical and pyrometallurgical apparatus and processes applicable to the efficient exploitation of rare earth deposits. Outotec has gained useful experience relevant to the processing of rare earths through several assignments including those for Alkane Resources Ltd. (Dubbo Zirconia Project), Greenland Minerals and Energy Ltd (Kvanefjeld Project), Frontier Rare Earths Limited (Zandkopsdrift project), Tantalus Rare Earths AG (Madagascar), Quest Rare Metals (Strange Lake project) and Orbite Aluminae Inc. (HPA project). The hydrometallurgical test work of two process flowsheets is presented in the paper. A roasting or acid baking step is common to several proposed rare earth projects. In the past, rotary kilns have been used, but Outotec has developed a new process concept to handle the rare earth material in fluid bed reactors. The basis for this development is long experience in fluid bed technology of Outotec in Germany. One advantage of fluid bed roasting is the higher throughput per unit. In combination with the roasting and baking, Outotec offers the gas cleaning and acid plant and provides a complete and closed concept.INTRODUCTIONRecovery of rare earth elements (REE) has obtained significant attention during recent years. It has been estimated that their demand will be boosted because of their need in many technology areas. REE can be utilized in magnets, batteries, displays, catalysts, optical devices etc. (Jordens, Cheng, & Waters, 2013; Zhang & Edwards, 2013). The production of REE is focused in China, which means that production outside of China is very scarce. However, there are multiple active development projects worldwide working towards production of REE containing products outside of China (Chen, 2011)."

Jan 1, 2016

By Antonio Segatori, Bjørn Holmedal, Kai Zhang, Trond Aukrust, Knut Marthinsen

"The visual appearance and mechanical properties of aluminium alloy extrusions are strongly dependent on the microstructure and texture of the extruded profiles, where the desired microstructure and texture may depend on the specific applications. In the present work, the evolution of deformation, as well as recrystallization textures during extrusion of AA6xxx aluminium alloys, have been experimentally and numerically investigated. Extrusion trials were performed in a laboratory extrusion set-up, which enabled immediate water-quenching of the profiles at the exit of the die, and thus the possibility to capture the deformation texture prior to post-extrusion recrystallization. The textures and their through-thickness variations were experimentally measured by the electron back-scatter diffraction technique (EBSD, and the deformation textures numerically modelled by coupling FEM flow simulations and crystal plasticity (CP) simulations. Different CP models as well as different choices of model parameters were employed and evaluated for texture predictions. With an appropriate choice of crystal plasticity model and model parameters, the deformation texture can mainly be predicted, although the accurate intensities are hard to reproduce. The corresponding recrystallization textures, either generated through spontaneous recrystallization of the extruded profiles or through post-extrusion annealing, are far more challenging to reproduce with available recrystallization models.INTRODUCTION Extrusion is a widely applied thermal-mechanical process to produce aluminium profiles. The properties of the profiles, for example mechanical, fatigue, fracture, corrosion as well surface appearance, are strongly dependent on the underlying microstructure and texture, and the requirements with respect to these aspects may vary with applications (Ralston et al., 2010; Dumoulin et al., 2012; Donati et al., 2013). Moreover, it is often a challenge to produce extrusions with a consistent and homogenous grain structure and texture along as well as through the cross section of the profiles. It is thus vital to understand and be able to predict (model) how different microstructures and textures are formed and how they evolve during and after extrusion, as basis for controlling the final appearance and properties of extruded profiles."

Jan 1, 2018

By Brian W. Mackenkzie, Jozef Lajzerowicz

This paper is intended to familiarize planners in the noncommunist world with the district planning approach used in eastern Europe for mining development. It deals generally with the basic nature of the district planning problem, the planning process for mining development and the state organization for the planning of mining districts. A number of applications of district planning techniques to both established and new eastern European mining districts are described.

Jan 1, 1971

By Y. Chino

Cross-rolling, in which the roll axis is tilted by 7.5 degrees against the transverse direction, was carried out on a commercial magnesium alloy. The (0002) texture intensity of the cross-rolled specimen was lower than that of the unidirectionally rolled specimen. Also, the grain size of the cross-rolled specimen was smaller than that of the unidirectionally rolled specimen. As a result of the Erichsen tests at 433 ? 493 K, the press formability of the cross-rolled specimen was higher than that of the unidirectionally rolled specimen. The high formability of the cross-rolled specimen is attributed to both the reduction in (0002) texture intensity and the enhancement of grain refinement by the cross-rolling.

Jan 1, 2006

By H. H. Wang

Construction safety documents regulate significant safety actions and requirements by which construction workers or employees should abide in order to secure them from occupational hazard events. Therefore, facilitating faster identification of applicable safety requirements from the documents has become an important topic in the construction safety domain. To address the need in this regard, tools and techniques have been developed and research efforts have been made. One of the research efforts is to utilize ontology, a knowledge representation and reasoning approach, as the methodology to achieve the goal of identifying applicable safety requirements. In such ontology-based researches, the development and construction of the safety concept ontology is an essential task as the concepts and the relationships between the concepts both representing key safety knowledge need to be carefully identified. In this paper, the author focuses on the safety documents without predefined concept structure and aims to address the concept and relationship identification difficulties. Specifically, the author leverages the Formal Concept Analysis (FCA) methodology, a theory of data analysis that identifies conceptual structures among data sets, to mine and analyze the documents in order to discover safety concept structure and to further assist the development of the concept ontology for the construction safety documents. The author expects the application of FCA to construction safety domain can eventually benefit the ontology-based approaches for identification of applicable safety requirements.

Aug 1, 2013

By Ye Chen, Jianhua Chen, Xianhao Long, Qingxia Liu, Zhenghe Xu

"It is crucial to understand the mechanism of the collector interacting with the mineral surface in the presence of water molecules, which could influence the relaxation and electronic properties of sulphide mineral surface due to the proximity effect for narrow band gap of semiconductors. The adsorptions of three typical collector molecules (xanthate, dithiocarbamate and dithiophosphate) on the sulphide mineral surfaces in the absence and presence of water molecule have been simulated by density-functional theory (DFT). The calculated results show that the adsorptions of collectors on clean mineral surface in vacuum are not in agreement with the observed flotation behaviours. The presence of water molecules has a great influence on the adsorption of collectors. The analysis of density of states of the mineral surface atom suggests that the adsorption of water molecules could influence the electronic properties of mineral surface and consequently influence the adsorption between the surface and the collector molecule.INTRODUCTIONIn the separation of multi-metal sulphide ores, the selectivity of a collector is a key factor for the efficient recovery of the aimed mineral. Xanthate, dithiocarbamate (DTC) and dithiophosphate (DTP) are the most common collectors used in the flotation of sulfide minerals. Generally, xanthate exhibits powerful collecting property but lack of selectivity. While dithiophosphate and dithiocarbamate show the good selectivity in the lead and copper sulphide mineral flotation. The mechanisms of these collectors interacting with the sulphide mineral had been attracted many attentions and several mechanism based on experimental results had been reported (Chander & Fuerstenau, 1974; Fuerstenau, 1990; Raju & Forsling, 1991; Crozier, 1991; Bradshaw, Cruywagen & O’Connor, 1995; Guler, Hicyilmaz, Gokagac & Emekci, 2006). However, the micro-mechanisms of the selectivity of these three thiol collectors on different sulphide mineral surfaces are not fully understood."

Jan 1, 2016

By A. F. Abd El-Rehim

The behavior of both transient and steady state creep of Al-4.5 wt% Cu and Al-4.5 wt% Cu-0.1 wt% In alloys was investigated using a constant stress where torsional oscillations of different frequencies and shear strain amplitudes were operated at various working temperatures. An augment in both transient and steady state creep rates was observed by increasing both frequency and shear strain amplitude of the applied oscillations. The mean values of the activation energy of both alloys for both creep stages were found to be equal to that quoted for dislocation intersection mechanism.

Jan 1, 2006

"Energy efficiency in mining and minerals processing has attracted considerable public and industry attention because of the significant quantities of energy consumption involved. In this context the question of what are worthwhile targets for energy efficiency improvements ought to be of the highest priority. It is however worth taking a step back to avoid falling in the trap of taking preconceived ideas that have been reiterated repeatedly before as gospel. The aim of this paper is to highlight areas where new or alternative approaches could potentially be the better way forward. Some may come as a surprise to conventional industry thinking. Ultimately any such solutions are attractive to practitioners not just in an environmental but also in an economic sense, and hence should be targeted through applied research and development efforts. This paper highlights key aspects of each group of opportunities and some of the individual approaches to provide an overview of the current status quo.MINING INDUSTRY POWER UTILISATION – WHERE IS THE BIGGEST BANG FOR THE BUCK?The question of where is the biggest bang for the buck when trying to determine worthwhile targets for energy efficiency improvements has not always been reported on broadly enough, typically because industry practitioners operate in specific areas of expertise and comfort zone. Looking beyond the familiar doesn’t always come easy. Any technology or methodology consideration to address energy efficiency needs to take into account the context of alternative opportunities of superior value or risks not achieving desired uptake. The following sub-chapters have been ordered by magnitude of improvement potential as best as is possible, starting with the biggest first, and the smallest last. Some may be a surprise relative to conventional mining industry thinking."

Jan 1, 2016