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By N. Depountis, Th. Rondoyanni, N. Sabtakakis, K. Kavoura, G. Tsiambaos

"Some typical landslide phenomena in Western Greece, in terms of the geological composition and structure of the affected materials, induced by heavy rainfalls are thoroughly studied and analyzed. The studied cases involved composite landslides on Flysch and Neogene weak rock materials that constitute the most critical landslide prone geological formations in Greece. The studied cases named Platanos, Platanitis and Karya include representative landslide sites as regards to the geological composition and structure of the displaced formations. Thus: (a) flysch formation includes different lithological units as shales, marls, siltstones, sandstones and conglomerates and is closely related to the Alpine orogenesis, suffering intense past tectonic movements and (b) the Plio-Pleistocene sediments include clayey marls, marlstones and siltstones. The investigated landslides , affecting mainly transportation routes, are closely related to heavy rainfalls induced by extreme meteorological events and are controlled by active fault tectonics. Long term movement monitoring using borehole inclinometers and surface benchmarks showed that landslides control was effective only when the proper stabilization measures were taken.INTRODUCTIONLandslides represent a major threat to human life, property, infrastructure and natural environment in most regions of the world. They are recognized by the scientific and politic authorities as having a major socio-economic impact and they represent a significant hazard for the population and the properties in particular locations. Landslide hazard expressed as the probability of occurrence within a reference time period and is a function of the spatial and temporal probability (Varnes, 1984; Guzzetti et al. 1999; Lee and Jones, 2004). The spatial probability of landslide initiation (susceptibility) is mainly related to static causal factors (slope inclination, material properties, etc.), while temporal probability is mainly related to dynamic causal factors such as rain input, increased groundwater levels and drainage, earthquakes, etc. (Van Westen et al. 2005)."

Jan 1, 2015

By L. Shasko, M. Hurlbert

As climate change is increasingly perceived as a problem, and fossil fuel based power production options are increasingly limited through regulatory restrictions and public distaste, future options become constricted. Reflexivity and social learning elicited through qualitative and mixed research methods offer important insight into what future power production pathways might be. Given factors of cost, baseload requirements, and energy density, options such as nuclear may be increasingly accepted. This paper explores this literature and possible methods of pursuing the reluctant acceptance of nuclear energy.

Jan 1, 2020

By R. Sharma, I. Miskovic, S. Miskovic

Solvent extraction (SX) is a widely used method for the extraction of copper from pregnant leach solutions or other ionic solutions in hydrometallurgical applications. About 17% of total refined copper production worldwide is produced using SX followed by electrowinning (EW). Conventional SX units, such as mixer-settlers, consume a large amount of extractant, offer poor process control and yield low extraction efficiency. Extraction efficiency is poor due to low specific interface area, crud formation, emulsification, and slow phase separation stage. Micro solvent extraction (micro-SX) is a rapidly developing technology that provides an opportunity for improved process control, higher extraction efficiency, lower residence time and, as such, has a potential to reduce the environmental footprint of SX operation. In this research, extraction of copper ions in an acetate buffer media is investigated using D2EHPA with kerosene as a diluent. Chemical factors such as extractant concentration and ionic concentration of aqueous phase are varied to determine the optimum conditions. Subsequently, the extraction efficiency and reaction time of new micro-SX reactors are compared against previous bulk SX studies. Extraction in the microfluidic reactor was observed to be faster with a residence time more than an order of magnitude lesser than bulk SX. This study forms a prelude for developing new modular micro-SX units which will enable continuous, effective, and safe operation on a large scale. In future studies, numerical and analytical models validated through this work will help eliminate rigorous experimentation and enable faster design and fabrication of micro-SX units. INTRODUCTION Conventional industrial solvent extraction (SX) units such as mixer-settlers, extraction columns present various disadvantages. Low specific interfacial area, crud formation, and emulsification in industrial reactors lead to long extraction times and severely hamper extraction efficiency (Priest et al., 2011; Chen et al., 2017). Microfluidic extraction considerably improves upon the current extraction practices by (1) creating a large surface to volume ratio that enables rapid mass transfer across the interface, (2) better process control, and (3) easier separation of phases (Kashid, Renken, & Kiwi-Minsker, 2011; Ciceri, Perera, & Stevens, 2014). These factors establish micro-SX as a crucial mode for process intensification. Although, a micro SX unit has significantly low processing volume than conventional extraction methods, their throughput can be increased via massive parallelisation (‘numbering up’), which is an area of active research (Darekar, Singh, Mukhopadhyay, & Shenoy, 2016a; Kriel, Woollam, Gordon, Grant, & Priest, 2016).

Jan 1, 2019

By M. Fujikawa

The Kamioka Zinc Smelter was converted from the jarosite process to the goethite process in the year 2000. The reasons for the conversion of the process were that the silica content of the raw material increased and the iron content decreased. The silica easily turns to a gel in sulfuric acid solutions and this causes the solid-liquid separation characteristics to deteriorate. The basic behavior of silica in sulfuric acid solution was investigated and it was found that the goethite process is the most suitable to effectively separate and remove silica from solution. Furthermore, Fe has the capability to remove elements such as Ge that have an adverse effect on zinc electrolysis. This means that, when the Fe content of the raw material decreased, the impurity removal capability also decreased and there was a risk of a build-up of impurities in the process. Iron precipitates in many forms in sulfuric acid solutions. The capability to remove elements such as Ge differs depending on the compound precipitated. Goethite has a higher capability than jarosite to remove elements such as Ge. In this report, the results of applying the process established by investigations of the basic behavior of Fe, silica and Ge in the zinc refining plant are presented.

Jan 1, 2006

By K. Nikkhah, N. Dhadli, G. Freeman

Ammoniacal pressure leaching operations have been in commercial use at the Fort Saskatchewan refinery of Sherritt International Corporation since 1954. Recent improvements have significantly increased the capacity of this circuit. The computer modeling of this process has proved to be a valuable tool in facilitating the evaluation of different operating scenarios in an effective manner. Reagent response in the ammonia leach of nickel and cobalt sulphides is examined using the dynamic process simulation capabilities of IDEAS(TM) software. The dynamic simulation enables accurate measurement of the sensitivity of the process to variables such as temperature, feed rate and ammonia concentration as well as compartmental analysis of metals concentration, pulp density, vent gas composition, and the formation of specific complexes. The complexity of the ammonia leach process makes it a logical choice for evaluation by computational analysis. The methodology for dynamic modeling of a pressure leach process is presented.

Jan 1, 2005

By Torsten Zeller

Due to the increasing worldwide demand for raw materials and the resulting rise in commodity prices more expensive processing that is able to utilize complex ores becomes economically viable. This and increasing ecological awareness is why the interest in recycling and urban mining is steadily growing in Germany. In addition to that; landfills do also contain elements, which were not targeted over the period, when they were being accumulated. Examples are rare earths, indium, gallium, cadmium, arsenic, selenium and tellurium. Also copper, zinc and lead, the target components of ancient mining, can be obtained due to more effective processing and smelting technologies. Funding by the German Federal Ministry for Education and Research, entitled "r³ ? Strategic Metals and Minerals ? Innovative Technologies for Resource Efficiency" also indicates the high level of strategic interest. It is against this background that the research project "Exploitation of the Raw Material Potential of Mining and Metallurgical Tips in Respect of Sustainability as Exemplified in the West Harz Mountains (ROBEHA)" has been implemented. A major concern of this project is the possible transfer of results to landfills in other areas. Therefore the development of an expert system based on the innovative processing methods and a method manual for urban mining are the central components of the investigation. This will provide an important contribution to the cost optimization of ensuing urban mining projects. To ensure the success of landfill mining projects it is necessary to record the composition and quality of the deposits accurately. Also the environmental impact caused by landfill mining and changes in the natural and cultural landscape will be considered in a multicriteria evaluation method. Depending on their origin the tips are divided into the categories mining, processing, and smelting. The content of a landfill and thus the economic potential in terms of urban mining is dependent on the type and composition of the deposits (host rock, gangue, and ore mineral), the available processing and smelting technology, and the target components at the time of mining. Zinc, for example, was not been processed until the 19th century, when it gained attention as being material of economic importance. After such knowledge about a landfill is obtained the decision for further investigations can be made. For a total of 158 landfills in the Harz Mountains, both the volume and the approximate contents of copper, zinc, and lead has been estimated for the different types of tips within past research projects. Based on the prices of the London Metal Exchange (LME) and a euro/dollar exchange rate of 0.76 (as of 03/05/2012) and assuming a minimum density of ? ? 1.5 t/m³ a average value of 1.6 billion ? in copper, zinc, and lead can be obtained. Although only these three metals are considered in this first estimate, it demonstrates the potential of landfill mining and the need for further research. KEYWORDS Urban Mining,

Aug 1, 2013

By H. Wotruba, K. Neubert

Dual-energy X-ray transmission (DE-XRT) imaging is known from safety luggage inspections at airports. The use of DE-XRT technology for sorting applications in the primary raw materials industry has been the subject of numerous investigations. Beside other metal ores, X-ray transmission sorting is already used for the preconcentration of tungsten ore, gold ore and coal. The applicability of DE-XRT sorting is limited to ore types where differences in metal concentrations are measurable, based on an interpretation of X-ray images. Metal contents in particles occur in large varieties in terms of concentration, grain sizes, spatial distribution and mineralogy and therefore influence the X-ray absorption. As a result, each ore has to be tested individually for its suitability for DE-XRT sorting. The objective of current research at the Department of Mineral Processing (AMR) at RWTH Aachen University is to assess parameters influencing the detectability of rare earth oxides. Two approaches were followed: (1) Practical test work, based on artificial ore samples of defined compositions and (2) Computer-based simulation of absorption features of identical particle compositions. In total, more than 300 artificial samples of various compositions and metal grades were produced and X-ray images from DE-XRT sorting were analyzed. Results from the DE-XRT sensor were put into correlation with metal grades and particle sizes, to analyze influences and limits on the detectability of rare earth oxides. In addition, a new approach was tested in which the X-ray absorption of particles of various compositions was determined based on a Monte Carlo (MCNP) simulation. During the simulation, similar compositions, as used for the artificial samples, were tested and the X-ray absorption behavior during DE-XRT sorting was determined. A comparison of results from both approaches is used to assess the applicability of the MCNP-simulation for the prediction of the X-ray attenuation behavior during DE-XRT sorting.

Jan 1, 2016

By S. M. Fatemi-Varzaneh

The AZ31 magnesium alloy is considered as a promising alloy in various applications and industries. Furthermore, to design a proper hot working process (rolling, forging and extrusion), the assessment of hot working behaviour of the alloy is necessitated. Accordingly, the hot deformation behaviour of AZ31 alloy was studied through hot compression testing method. The latter was carried out in a wide range of temperature (523 K to 783 K) and strain rates. The obtained true stress-true strain curves and final microstructures were examined and a partial melting was realized at 740 K. It was concluded that the presence of liquid did change the deformation mechanisms thereby affecting the flow behaviour.

Jan 1, 2005

By J. C. Kurnia

Methane is recognized as one of the prime causes of underground mine disasters around the globe. A cost-effective mine ventilation system and methane control is required to ensure a safe and productive environment in an underground mine whilst keeping energy usage and operating cost at minimum. Typically methane enters a mine environment or tunnel from localized distributed sources at high initial concentration. Hence, an understanding of its dispersion from discrete sources is important to design a methane management system via effective ventilation. This study employs computational fluid dynamics to model methane dispersion in an underground tunnel which has a number of discrete sources of methane and effective ways to dilute and or disperse it. Air flow distribution within the tunnel as well as methane dispersion is simulated by solving the governing transport equations subject to appropriate boundary conditions. First, the effectiveness of ventilation duct placement is examined. Several possibilities are explored and investigated. It is found that the common configuration utilized in underground mine performs best as compared to other configurations in maintaining the concentration of methane below permissible levels. Next, a novel intermittent airflow ventilation system is proposed and evaluated via simulation with the goal of reducing the energy cost whilst maintaining methane level in the mining face below the allowable level. Parametric studies are conducted to investigate effects of various factors influencing the effectiveness and performance of this novel intermittent ventilation system. This study will provide some new ideas for designing an efficient and effective underground mine ventilation system by lowering the net average amount of air that needs to be circulated in the tunnel for a safe operation. KEYWORDS

Aug 1, 2013

By X. F. Liu, O. Buzzi, Y. Sieffert

This study falls in the context of underground coal fires (UCF) where burning coal can elevate the temperature of a rock mass in excess of thousand degrees. The objective of the research was to experimentally investigate the change in mechanical behavior of a rock when subjected to temperatures up to 900 °C. Several blocks of an Australian mudstone were collected from a mining site in New South Wales, Australia. X-ray diffraction and thermal-gravimetric analysis were conducted on powdered rock in order to determine the critical temperatures at which the main mineralogical changes occur. Then, cylindrical specimens were prepared from intact rock blocks for unconfined compression tests. These rock specimens were then treated by heating in a temperature-controlled furnace at temperatures varying from 100 °C to 900 °C. The heating process consisted of two stages: raising temperature with very slow rate of 1 °C per hour followed by a holding period of 24 hours and then a slow cooling process to room temperature. The compression tests were carried out on treated rock specimens to characterize the change in compressive strength. The macroscopical study was complemented by microstructural investigations via optical microscope, scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP). Results show that the unconfined compressive strength of mudstone decreases with increasing heating temperature up to 450 °C, beyond which it increases. This can be explained by the combined effects of micro cracks and mineral thermal reactions caused by heating process.

Jan 1, 2015

By J. J. Benitez

MIBC (methyl-isobuthyl carbinol) was previously shown to enhance significantly sylvite flotation when used at the stage of preparation of amine dispersions. In this paper Atomic Force Microscopy (AFM) is used to study the effect of MIBC on deposition of octadecylamine (ODA) on the surface of mica. The AFM images indicate that amino terminated, and therefore hydrophilic, deposits of ODA are observed on the mica surface in the ODA dispersions free of MIBC. In the presence of MIBC a methyl terminated (hydrophobic) monolayer is obtained on the mica surface. The transition between the monolayer and bilayer phases is due to the presence of MIBC. Experiments carried out in distilled water reproduced the results obtained from the brine. Working in pure water instead of brine simplifies the preparation conditions and the analysis by AFM.

Jan 1, 2006

By L. Voisin, K. Mühlenbrock

A new pyrometallurgical process is proposed for cleaning complex copper matte and for recovering copper from copper scrap containing lead. In the process, a given amount of pig iron is added to the complex material under a reducing condition to produce two or three liquid phases at the equilibrium, depending on the content of sulfur in system, of copper-rich and iron-rich alloys, and matte, respectively. The novel process is proposed based on the experimental results obtained by performing laboratory scale tests in an electrical furnace at 1473 K followed by a quenching method on the final stage. The samples obtained from the experiments were analyzed by using Atomic Absorption Spectroscopy (AAS), Inductively Couple Plasma (ICP) and Carbon Infrared Spectrometry (CIS) techniques. The results were discussed on the basis of the distribution of lead as impurity in the miscibility gap where equilibrated phases coexist. According to the mass balance calculations, the elimination of lead into the iron-rich alloy phase as a harmless and smaller deposit might be feasible and the process proposed for cleaning the complex matte would be promising.

Jan 1, 2014

By E. E. Mueser

As Mr. Lundberg has already ably covered the theory of various methods of electrical prospecting, I shall confine my remarks to a consideration of the features which must obtain in an electrical prospecting method in order that it may be useful from a practical standpoint. These remarks I shall make with particular reference to the Elbof method. The successful application of all these methods rests, in the first place, upon the possibility of correlating theory, or empirically established facts, with the field data. Their practical usefulness, however, requires that the technique of making the field observations, and the procedure itself, be such that the method may be applied to large areas, under normal average conditions. The method, therefore, should not involve excessive preliminary labour costs to prepare the ground for actual prospecting work, nor should the prospecting work itself be so slow that its cost, when applied to extensive areas, becomes prohibitive. Moreover, it should be possible to apply the method even under difficult terrain conditions, such as rough topography and dense vegetation. It may be said of most of the methods referred to in the preceding paper, that, while they are interesting and theoretically sound, they fail to meet such practical requirements as I have outlined.

Jan 1, 1926

From 1999 to 2008 rock related accidents accounted for 75 fatalities, nearly 6,000 injuries and almost 14,000 incidents (Pappas and Mark, 2011). Clearly this shows that rock related safety on coal mines remains a serious issue and more effort is needed to address this hazard. This paper reviews support design considerations and monitoring needed to improve rock related safety in room and pillar coal mines in the USA. From the present study design considerations continue to evolve and improvements in technology and a better understanding of failure mechanisms and methods to prevent these failures from occurring are in place. At first glance, the design of safe and efficient underground openings appears simple until the designer begins to realize the complexities and variability of geometries, geology, loading and stress influences, support designs and other factors such as corrosion and economics. Ultimately the goal of all designs is to ensure that it can be completed safely, last for the duration of the design life and it is economically feasible.

Aug 1, 2013

By M. Potesser

In the past, different furnace types have been developed for use within the copper industry, with two common anode furnace designs typically used in copper smelting plants worldwide: the tiltable reverberatory furnace (KPO) generally used for the secondary copper industry and the cylindrical or drum type anode furnace (TRO) for handling a liquid blister charge generated in primary copper production. The disadvantage of the KPO is its design related to the longer refining period, because of the low bath depth, however it provides good conditions in the melting period due to its large bath surface. On the other hand, small amounts of scrap charged into the TRO increase the melting and dissolution period, but it provides good conditions for the refining period. The newly-developed elliptical furnace concept (TRE) offers the advantages of each of these furnace types. The special design allows melting of the scrap more efficiently than in the KPO and refining the liquid copper more efficiently than the TRO. This paper shows a metallurgical comparison of the three furnace types in regard to the melting period by heat technological considerations (optimized arch design) and of the refining period done by CFD with concentration on current, recirculation and dwell time of the gas in the melt. The paper outlines the possibilities for a reduction of the tap-to-tap time and energy consumption as well as for an increase of the production capacity, which can be achieved by applying the TRE instead of the conventional furnace designs.

Jan 1, 2007

By W. N. Roman

This paper will examine the challenges involved in ventilating and cooling South African mines, with particular emphasis on solutions to the issues of heat (generally associated with depth), mechanization and energy efficiency. Comparisons will be made with other international mining areas. Some of the deepest mines in the world are to be found in the South African goldfields. The Mponeng mine is approaching 4,000 m below surface, with virgin rock temperatures (VRT) of between 60°C and 70°C. Mining at these depths has only been possible with the use of large refrigeration plants supplying cold air, water and ice to the workings. In the Bushveld Igneous Complex, where most of South Africa?s platinum mines are located, similar VRTs are being experienced at significantly shallower depths. This is due to the different geothermal properties of the host rock between the two areas. Existing mines are being forced to go deeper and new underground mines are being planned and constructed in other areas with widely differing thermal conditions. South African metal mining has traditionally been labour intensive for historical reasons as well as for the narrow tabular nature of many ore bodies. Due to cost pressures and labour problems, some mines have been investigating the possibility of using mechanized equipment, both diesel and electric, to increase production and to improve efficiency. Studies have been carried out to determine the effect of the additional equipment on the overall ventilation system and some of the conclusions are discussed. The use of diesel equipment adds heat and pollutants to the ventilation air but, although electrical equipment has a lesser effect on the ventilation systems, it is generally less favoured due to claims of lower flexibility/manoeuvrability. Mechanization holds the promise of more concentrated mining activities but, with higher localized ventilation and cooling needs. Systems which will control the provision of air and cooling more effectively are required and are being implemented. In the 1990s and early 2000s, the South African economy experienced significant growth which was not matched by the growth in infrastructure. Consequently, at present there is a shortage of electricity generation capacity which affects large industrial consumers, including mines. Increasing levels of heat and mechanization will require more electrical energy for ventilation and cooling. There are many initiatives underway to save power or to shift consumption to periods of national low demand and these will be described.

Aug 1, 2013

By Z. Trojanová

The deformation behaviour of ternary magnesium alloys AJ (Mg-Al-Sr) and AX (Mg-Al-Ca) were investigated in tension as well as compression tests. The samples were deformed at temperatures between 20 and 300 °C and at an initial strain rate of the order 10-4 s 1. The flow stress decreases with increasing temperature. The macroscopic work hardening rate decreases with increasing flow stress and temperature. The stress and temperature dependence of the work hardening rate is a result of the hardening and softening processes. Stress relaxation experiments were performed in order to reveal features of the thermally activated dislocation motion. Internal and effective stress components of the applied stress were estimated. A decrease in the internal stress was observed at elevated temperatures, which indicates recovery process (-es). A more detailed analysis of the estimated values of the activation volume and activation energy helped to interpret the thermally activated processes during plastic deformation. It is concluded that the deformation behaviour of the alloys depends on the activity of non-basal slip that is strongly influenced by temperature.

Jan 1, 2007

By I. Ciabatti

Inorganic salts of hexavalent iron (ferrate (VI)) are versatile reagents for water and industrial effluent treatment because of the strong oxidising effect of the ferrate ion (FeO42-) and the well-known coagulation properties of the resulting ferric ion. Among other applications, ferrate can effectively remove arsenic, cyanide and phenols from industrial effluents. Furthermore, ferrate salts can be prepared from ferrous sulphate, a common byproduct of the steel and titanium industries, and possibly from other iron wastes. Notwithstanding their many potential advantages, the industrial-scale application of ferrate salts, such as potassium ferrate (K2FeO4), for effluent treatment has been hindered by the difficulties inherent in their synthesis and stabilisation. Within a project co-funded by the European Commission, the large-scale synthesis of stabilised potassium ferrate was realised through a new synthesis process, and different applications of the resulting ferrate to effluent and wastewater treatment are under investigation. This paper reports the results of the application of stabilised potassium ferrate for the purification of textile effluents. Laboratory and pilot-scale tests were carried out and the performance of the ferrate was compared to that of chemicals currently used in wastewater treatment. According to these experiments, potassium ferrate is a promising reagent for an effective treatment of textile and other industrial effluents.

Jan 1, 2006

By A. M. L. Cushing, S. Kelebek, A. Ghahreman

Iron sulfides are part of many ore deposits affecting flotation separation of non-ferrous base metals from them. Open-circuit potential (OCP), potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) measurements were carried out with pyrite and pyrrhotite electrodes to investigate their reactivity under various flotation conditions, which involved the use of TETA, SMBS, and their combination. TETA was found to adsorb on the electrode surfaces causing a significant increase in charge transfer resistance of the product formed, which was most significant at OCP. This effect is much less with SMBS, indicating its greater surface reactivity compared to TETA. The combined use of these reagents decreases charge transfer resistance to a greater degree than that experienced with their individual uses. Addition of Cu2+ as a potential activator to this system nearly eliminates the action of TETA on the electrode surface, which can be attributed to sequestration/chelate formation in liquid phase. The relative effects of these reagents on pyrrhotite electrode are similar to that of pyrite. The main difference between the pyrite and pyrrhotite electrodes is that the observed charge transfer resistance on the pyrrhotite surface with each reagent case is significantly lower by 3 to 4 fold. This is compatible with its anodic nature and ease of oxidation since the OCP value of pyrrhotite is lower than that of pyrite. Results are discussed in relation to flotation/depression behavior of these iron sulfide minerals in mineral separation processes.

Jan 1, 2017

By M. S. Badollet

"IntroductionAsbestos as received by the manufacturer of asbestos products is •in the •form of either crudes or milled fibres processed to different degrees of texture. Frequently, the manufacturer finds that l:ihe fibres as he buys them are not adaptable to his plant processes, and, therefore, it is necessary for him either to contact the mine supplying the material and request a specific texture for the :fibre or to reprocess the fibre in his own plant.When the mine or mill manager is requested to change his milling equipment to produce a special grade of fibre with a specific texture, he would like to comply. However, if he began to make special fibre grades for each customer, he would be in the position of constantly rearranging his milling technique, adding more equipment, or building a new mill. In the end, his mill would he producing hundreds of different fibre grades of varying degrees of texture, which is a difficult accomplishment if he desires to maintain any quantity of production."

Jan 1, 1950