Search Documents

By D. A. Akinlade, N. L. Richards, D. C. Murray, W. F. Caley

To investigate the effect of adding Ti to a Ni-Cr-Fe powder metallurgy alloy, a thermodynamic software package was used to predict the phase transformations that occurred during thermal processing. Specifically, the effect of adding 3w/o Ti to a 6w/o Al modified ternary Ni-Cr-Fe alloy (the quaternary) was simulated and the phase transformations that might occur in the material on sintering were obtained using the thermodynamic modeling tool. These predictions were subsequently compared with experimental results obtained by X-ray diffraction and metallography. For comparison, selected compacts were prepared containing only the ternary + 3w/o Ti (no Al). Based upon compressibility curves, the optimum pressure for producing the new Ti compacts was 500 MPa vs 600 MPa for the quaternary composition with Ti. In each case, hardness of the base alloy was enhanced by the Ti addition whereas the residual porosity remained relatively constant at about 19%. Finally, although SEM/EDS failed to confirm the presence of Ti in the gamma prime intermetallic, XRD spectra showed a shift in lattice parameter on addition of Ti, suggesting that the intermetallic was of the form Ni3(Al,Ti).

Jan 1, 2010

By Jan Drzymala, Przemyslaw B. Kowalczuk

"Flotation is possible when the forces operating between a bubble and the attached particle are properly balanced. There are many forces operating in the bubble-particle aggregate. The magnitude, location and direction of the forces depend on the type of process. The simplest arrangement in flotation is when a spherical bubble is attached to a spherical particle and both are immersed in water. In such a system there are four essential forces which shape the stability of the bubble-particle aggregate. They are excess pressure and interfacial solid/liquid, solid/gas and liquid/gas forces. A proper analysis and balance of the size, location and direction of these four principal forces lead to a general equation delineating the stability of the spherical particle–attached bubble system. Specific cross sections of the system and solution of the general equation lead to different relationships including the Young formula as well as the well-known geometrical relation between contact angle, particle and bubble radiuses. The arrangement of forces in the proposed graphical representation of the Young law is different from that presently used in literature for a bubble attached to an unmovable solid particle. Many real solid/liquid/gas systems are more complex due to the presence of additional forces which change the regular curvature of the liquid/gas interface leading to advancing and receding contact angles.INTRODUCTIONThere are numerous papers (Athukorallage, Aulisa, Iyer & Zhang, 2015; Chau, Bruckard, Koh & Nguyen, 2009; Drzymala, 1994; Lubarda, 2012; Pellicer, Manzanares & Mafe, 1995; Wang, Cui, Zhou, Xu, Sun, & Zhu, 2014; Young, 1804) and books (Davies & Rideal, 1963; Defay & Prigogine, 1966; Lee, 2013; Lyklema, 2000) dealing with the solid/liquid/gas system. Many of them concern the three involved phases having the shape of a sphere or spherical cap and the formed contact angle. The contact angle is usually measured through the liquid phase and can be either smaller or greater than 90o. The essential part of these publications is a graphical representation of the system with the Young equation shown as a result of balance of only three forces that is the excess Gibbs (or Helmholz) free energy per unit area of the three involved interfaces (Davies & Rideal, 1963; Defay & Prigogine, 1966; Israelachvili, 1985) (Figs. 1a-c). The Young equation, when the gravity force/buoyancy is neglected, is:"

Jan 1, 2016

By Youngsoo Song, Hyunjung Kim, Junhyun Choi, Siyoung Q. Choi, Gahee Kim

In this study, for the first time, to confirm the effect of bacterial growth phase on the malachite flotation were investigated in a well-controlled Hallimond tube system. The test results showed that the bacteria in the stationary phase exhibit two-fold greater floatability than those in mid-exponential phase. To understand the observed flotation behavior, complementary cell characterization tests and cell attachment tests were conducted. Interestingly, the bacteria at both phases exhibited similar surface properties as well as almost identical amount of cells attached onto the malachite, suggesting that the growth phasedependent flotation behavior cannot be attributed to the variation of cell surface properties and the extent of cell adsorption. On the other hand, cell detachment tests revealed that the amount of cells detached from the malachite surface is greater for the mid-exponential phase than the stationary phase due to the higher fluid drag applied to the cells at the mid-exponential phase, which was explained by the differences in the size and shape of attached bacteria onto the malachite surface. These morphological characteristics were found to cause the bacteria of mid-exponential phase to be separated highly sensitive and easy from malachite surface due to the fluid flow. Second, scale-up selective bioflotation tests were carried out in a 1 L Denver cell in malachite–silica binary mixture systems. Through the tests, we optimized the cell concentration and the malachite fraction in the feed. Overall, high malachite selectively was observed under optimized conditions (both recovery and grade showed more than 90%). The trend was in agreement with classical DLVO interaction energy profiles, which show the relative magnitudes of the adhesive forces between the mineral and the attached cell under equal hydrodynamic conditions.

Jan 1, 2016

By A. G. Beer

The evolution of microstructure is examined during the annealing of hot worked magnesium alloy AZ31. The influences of deformation and annealing conditions on the developed microstructures are assessed. It is found that annealing at a low temperature (300 °C), after deformation at a low temperature and strain rate (300 °C and 0.001 5-1 respectively), results in the development of abnormally large grains. With increasing values of Z (lower temperatures, higher strain rates), static recrystallization of the dynamically recrystallised structure takes place; smaller annealed grain sizes are attained and the time at which coarsening begins is reduced. Whilst both the deformation and annealing conditions influence the time it takes to reach a stable annealed microstructure, the grain size attained is governed solely by the prior deformation conditions employed.

Jan 1, 2006

By Z. Zhang, X. -G. Chen, F. Breton, A. Arici

"The microstructure of Al-10Si-0.3Mg-0.5Mn alloy with 0.27% Zr and 0.19% V addition was quantitatively analysed and compared to the base material. The addition of Zr and V in the AlSi10Mg alloy exhibit a beneficial effect on the Si modification, resulting in the reduction of the size of eutectic Si particles on both as-cast and T6 conditions. The quantitative image analysis results show that the Zr and V addition and T6 treatment can reduce the size of the intermetallic phases. In addition, the presence of Zr and V is favour to the partial dissolution of the intermetallic phases during the T6 treatment. Different heat treatment procedures were tested to optimize treatment parameters. The mechanical properties of the alloys were evaluated using hardness measurements and tensile tests. The results show that the addition of Zr and V can remarkably improve the mechanical properties on as-cast and T6-treated conditions. The correlation between the microstructure and mechanical properties of the alloys is discussed.INTRODUCTION Al-Si-Mg foundry alloys have been widely used in automotive and aerospace industries due to their high strength-to-weight ratio, heat-treatable capability and excellent castability. The alloying elements such as Cu, Mn, Fe are traditionally added into Al-Si-Mg alloys to improve their mechanical properties (Mohamed, Samuel, Samuel & Doty, 2009). In recent years, the attention has been paid to the effect of the transition elements such as Zr, V, Ti, etc, as minor alloying additives, on the properties of aluminum alloys (Elhadari, Patel, Chen, & Kasprzak, 2011; Kasprzak, Amirkhiz & Niewczas, 2014; Shaha, Czerwinski, Kasprzak, Friedman & Chen, 2015; Shaha, Czerwinski, Kasprzak & Chen, 2014; Mahmudi, Sepehrband, Ghasemi & 2006; Meng, Cui, Zhao & Zuo, 2013). Kasprzak et al., (2014) and Shaha et al., (2015) reported that additions of Zr, V, and Ti in Al-Si-Cu-Mg cast alloys can improve the alloy mechanical properties at high temperature by forming stable intermetallics and precipitates on as-cast and heat treatment conditions. On the other hand, the mechanical properties of near-eutectic and eutectic Al–Si cast alloys depend not only on the chemical composition but also, even more importantly, on microstructural features such as the morphology and size of eutectic silicon and intermetallic particles, which are present on both as-cast and heat treatment conditions (Mohamed et al., 2009). However, there is rather limited information on the effect of Zr and V on the microstructure features and mechanical properties of near-eutectic Al-Si-Mg cast alloys."

Jan 1, 2018

By I-H. Jung, J. Kim

"Mg alloys are extensively used as light structural materials in modern industry. Mn and RE (rareearth) metals are effectively used as alloying elements to enhance the properties of Mg alloys. Therefore, the thermodynamic database of those alloys is important in the Mg alloy design and processing. Critical evaluation and optimization of all available literature data for the Mn-RE systems were conducted to obtain reliable thermodynamic functions. The Mn-RE systems shows systematic changes in the phase diagrams and thermodynamic properties with increasing atomic number in the lanthanide series. This systematic approach for all RE elements allows to resolve inconsistencies in the available experimental data. INTRODUCTIONRare Earth (RE) metals are widely used in many industrial fields including permanent magnet, electronic materials and structural materials. As a small addition of RE can enhance magnetic, electronic, optical and mechanical properties of numerous materials, the usage of the RE is still expanding regardless of the strategic control of their supply.Magnesium alloys are getting great scientific and industrial attention as the lightest structural materials. One of the drawbacks of Mg alloys is their poor formability at room temperature due to the limited slip system with hcp crystal structure. Recently, several studies (Farzadfar et al., 2011; Sandloebes et al., 2010; Stanford, 2010; Stanford et al., 2008; Yan et al., 2010) show that the additions of small amounts of RE can considerably enhance the ductility of Mg alloys. Therefore, a lot of research on Mg-RE alloys is undergoing to clarify the role of RE on the enhanced deformation mechanism and to find out the most optimum Mg alloy compositions. In order to respond to the need of Mg-RE alloy development, a large thermodynamic database for Mg alloys containing RE has been developed with critical systematic analysis and optimization of the entire RE series data. This includes the thermodynamic database of the Mg-RE (Kang et al., 2009), Mg-RE-RE (Kang et al., 2009), Mg-Al-RE (Jin et al., 2011; Jin et al., 2010), Mg-Zn-RE and Mg-Mn-RE systems."

Jan 1, 2012

By N. Musee, N. Kornelius

This study presents a neural network approach to modelling the liberation of gold bearing ores. A complete mineralogical analysis of unmilled and milled ores, including gold deportment and gangue content are used as inputs to a self-organising neural net which generates order preserving topological maps. The arrangement and shapes of these clusters are coupled to unmilled free gold data to predict gold liberation in milled ores (absolute error: 4.2%). Moreover, the self-organising maps were diagnostic of the quality of data used, indicating that the relationship between particle size and gangue material content requires further investigation.

Jan 1, 2005

Productivity and efficiency of diesel-powered underground trucks and LHDs can be enhanced through the application of a range of advanced technologies. In addition, these machines are subject to ever more stringent emissions control requirements. This paper will review how various technologies can improve usability, maintainability, and performance of LHDs, through a number of examples. The use of instrumentation and monitoring to understand the role of operator practice on mucking efficiency, as well as the use of finite-element analysis to evaluate structural design, and the use of control techniques to modify operator inputs and hence decrease power consumption, will be presented.

May 1, 2002

By J. Chlan

"Dryer DescriptionProctor and Schwartz Continuous Conveyor DryerThe Proctor and Schwartz Continuous Conveyor Dryer has been in operation since July 1958, and comprises six unit• - an 8• wide single conveyor with roller extruder, insulated housing, type 304 stainless steel circulating and exhaust fall system, steam heating coils, temperature controls and discharge crusher rolls. Entire dryer dimensions are 52’ x 12'0""weighing 53,000 lbs,Extruder rolls - setting is 1/8"" (Drive 3 HP 1800 RPM) clearance off the extruder screen.Conveyor - consists of 151 interlocking pans, measuring 8"" x 8' (2 HP 1200 RPM) One Exhaust Fan (5HP - 900 RPM)Steam Coils -- l"" steel pipe - with steel fins -- each coil measures 16' 2’’- 64 coils in the No, 1 Compartment- 64 coils in the No, 2 CompartmentDryer OperationThe yellowcake slurry at 28% solids is pumped to an 81 x 8' Peterson Filter. The filter media presently being used is a Neotex 4372 blanket, being 100% staple fibre nylon, 12 oz per square yard with air porosity of 9 CFM's. The cake discharge at 45 - 50% moisture falls into the roller extruder. Extrusions are formed by forcing the material by rolls through a perforated plate moving back and forth and depositing the spaghetti-like extrusion on onto the dryer-conveyor.The conveyor now carries the extruded material through the heating chamber•, The feed end of the dryer will be referred to as No. 1 Compartment, with temperature control set at 280""F. The circulating fans take the hot air off the coils and circulate the heated air through the perforated openings in the dryer conveyor pane, After passing through the set of steam coils and circulating fan in No, 1 Compartment, the material then goes through No, 2 Compartment where the temperature is set at 305'F, Final material then discharges through a set of crusher rolls set at ~"". Moisture of final dried product runs at less than 2%.The dryer conveyor load is usually run to a 3"" - 4"" depth load. Conveyor speed at approximately 90 minutes for load to pass through. Load onto the conveyor is controlled by boot level and speed of the 8' x 8' filter. The dryer steam coils are water-washed twice a month."

Jan 1, 1972

By D. A. Whitley, R. P. Carone

"Shaft sinking by blind shaft drilling offers the mining industry a different approach to shaft construction. Benefits of blind drilling include less construction time and fewer safety problems while being economically competitive with conventional sinking methods under certain conditions in soft water-bearing formations.Technology and equipment are available today to drill blind shafts up to 20 feet in diameter and over 3,000 feet deep. This is an extension of proven techniques developed by private industry. To drill a 20-foot-diameter hole requires a specially manufactured hydraulic drill unit with a rated hoist of 2 million pounds and 500,000 ft/lb of torque.This brief paper will discuss the following aspects of blind shaft drilling:• benefits;• equipment f or drilling;• circulation methods;• circulation rates;• shaft alignment; and• progress rates to be expected.IntroductionShaft sinking by blind shaft drilling offers the mining industry an improved alternative method for shaft construction. The drilling of 20-foot -diameter shafts to depth s in excess of 3,000 feet can be done by utilizing equipment specifically designed and manufactured for this purpose. This equipment is a distant cousin, at best, to standard oil well drilling rigs. The actual configuration of these drilling machines will be discussed in a following section.To most people, the drilling of mine shafts may seem to be a new or at least recent technology. However, as early as the I920s, German and Dutch miners were drilling 24-foot diameter shafts for coal mines. What led ""miners to resort to drilling were ground conditions that still plague conventional shaft sinkers today: soft , water-bearing formations. The major drawback to these early attempts was a low penetration rate due to poor bit cleaning. This, however, was not the end of early shaft drilling activity. From 1936 to 1950, a number of mine shafts were drilled by the calyx or coring method. This method employs a bit with a large bore down the center. As it drills, it cuts a core. When 5 to 10 feet have been drilled, the core is removed. The disadvantages of this method were the time and work involved in breaking the core free, and it was inadequate in soft water-bearing ground."

Jan 1, 1981

By D. Song

In this paper, the differential equations governing the mass transport and the electrochemical reaction in a cathode catalyst layer of polymer electrolyte membrane fuel cells are solved based on the polynomial series expansion method. Explicit expressions for the polarization curve as well as for the distributions of oxygen, current density and overpotential are obtained when a quadratic, cubic or quartic polynomial is employed to approximate the oxygen concentration distribution. These kinds of explicit solutions are desirable for MEA design and diagnosis purposes. The comparison between the conventional numerical approach and the explicit solution approach proposed here shows that satisfactory accuracy can be reached by the first four terms of the polynomial series. The effect of the catalyst layer thickness on the accuracy of the obtained explicit polynomial solutions is also discussed.

Jan 1, 2005

By J. Ouellet

The authors participated in a study for a new mine shaft in Saskatchewan?s Athabasca Basin where ground freezing is desired to reduce water inflows. Constraints were imposed on the design in terms of permissible water leakage (less than 10 m3 / hour) inside the shaft. Since the shaft goes through highly permeable formations, water control measures had to be incorporated into the design. Ground freezing was selected as the most reliable and proven method for the sinking and a hydrostatic liner design was implemented. While exploring various technological options available for providing a fully hydrostatic liner, the authors came up with a new design concept that offers a more cost effective solution while meeting all the design constraints. The new liner concept is a composite design using concrete and a sprayed-on membrane system. A proof of concept program comprising laboratory testing and field testing was successfully implemented. This paper presents the innovative liner design, as well as the adapted sinking methodology, developed for this type of project. The new concept offers a new cost effective high performance hydrostatic mine shaft liner comparing favorably with traditional methods. RESUME: Les auteurs ont réalisé une étude pour un nouveau puits de mine dans le Bassin de l?Athabasca en Saskatchewan. Des limites sévères sont imposées sur le design en terme de volume d?infiltration d?eau acceptable (moins de 10 m3 / heure). Comme ce puits de mine traverse des formations très perméables la congélation des terrains a été sélectionnée, une méthode éprouvée et fiable. Un design hydrostatique a été choisi pour le revêtement du puits. Dans le processus de design, les différentes technologies disponibles ont été étudiées. Les auteurs ont développé un nouveau concept de revêtement composite offrant un rapport performance/prix plus avantageux que les technologies conventionnelles. Le nouveau design proposé est composé de béton et d?une membrane projetée. Un programme expérimental a été réalisé pour démontrer la faisabilité du concept. Cet article présente le nouveau concept ainsi que la méthodologie de fonçage de puits adaptée. Ce concept innovateur offre un revêtement hydrostatique performant à un cout avantageux par rapport aux techniques de construction utilisées jusqu'à maintenant.

Jun 1, 2012

By P. J. Oakley, W. M. Thomas, S. W. Kallee, D. G. Staines

A Friction stir welding (FSW) is now extensively used in aluminium industries for joining and material processing applications. The (FSW) technology has gained increasing interest and importance since its invention at TWI almost 15 years ago. The basic principle, recent applications and the continuing development of the FSW technology are described. The paper will introduce some of the variants of FSW, such as Dual-rotation, Twin-stir(TM), and the Stir-lock(TM) technique.

Jan 1, 2006

By A. Ehsani

"Seas and oceans constitute about 70% of the earth’s surface. They contain an enormous stock of various mineral resources such as sedimentary (marine placers), massive sulfide ore deposits, manganese nodules and cobalt-rich ferromanganese crusts. Sea and ocean floor ore deposits could well contribute to the meeting of ever-rising demand for raw materials in the metal industry. In this regard, more research and development in science and technology appear to be required to ensure maximum benefit from the mineral resources of seas and oceans. Since the 1960s, a variety of mineral and metallurgical processes have been studied and developed to deal with marine ores and to extract metals such as gold, nickel, copper, cobalt, manganese, tin, platinum group metals (PGM), zirconium, thorium, etc.In marine environments, there are many parameters which can affect the selection of the mineral and metallurgical processes. These include the extent and grade of the deposit, mineralogical and chemical properties of the deposit, and physical properties of minerals present with particular reference to particle size distribution and mineral liberation size.In this paper, we briefly review the latest trends in processing and extraction of marine mineral resources. Mineral processing technology is mostly applied for recovery of precious metals i.e. gold and PGM, in particular, from marine placers. In general, pre-treatment (sizing, classification, dewatering), gravity concentration techniques (shaking tables, spirals, jigs, etc.,), flotation, magnetic, and electrostatic separation are the options for enrichment of marine placer ore deposits. In the case of massive sulfides, manganese nodules/cobalt-rich crusts, hydrometallurgical and pyrometallurgical methods (as proven technological methods) can be exploited for extraction of metals from concentrates after physical separation or directly from marine ores. The hydrometallurgical treatments involve acid (e.g., sulfurichydrochloric) and alkaline (e.g., ammonia) leaching with different reducing agents and pre-treatments such as roasting. Alternatively, pyrometallurgical treatments involve mostly smelting, chlorination and segregation processes."

Jan 1, 2016

By Maurice Morton

THE use of organic and inorganic stains has found wide application as a means of detection and estimation of organic fibres. Such stains have enabled the analyst to distinguish between organic fibres of different type and even between wood fibres produced by different processes. Among these stains, aqueous iodine solutions have figured prominently, as in the case of the well-known Sutermeister and Herzberg stains. At the Johns-Manville laboratories, the idea of applying a stain to asbestos fibres was first considered solely as a visual aid in the microscopic examination of such fibres. The staining medium used in this work consisted of a 1 per cent solution of iodine in C.P. glycerine, the latter being used extensively here as a dispersing and mounting liquid for asbestos fibre. This iodine solution was found to have distinct staining properties when used on the local chrysotile fibres, and to improve greatly their visibility under the microscope. It was soon revealed, however, that this staining is apparently limited to the chrysotile variety of asbestos, as against other varieties. It can be readily seen that, if such were the case, the staining test would become a very useful tool in differentiating between chrysotile fibre and the other mineral fibres, without recourse to a lengthy chemical analysis. Hence this investigation was launched, with the purpose of obtaining more information as to the selectivity of this stain as well as its mechanism. The only previous work of this nature that could be found in the literature was that of Van Winsen and Graham (1, 2, 3) on the adsorption of erioviolet dye by serpentine and related magnesia minerals. However, these authors did not refer to any specific behaviour of chrysotile as against other types of asbestos fibre.

Jan 1, 1941

By A. Kapoor, L. Morin, S. Mortazavi, P. Béedard, Gould. W. D., A. Kuiper

The degradation of thiocyanate in a simulated gold mill effluent was studied using a laboratory scale rotating biological contactor (RBC). Complete SCN- removal was obtained at temperatures of 8 and 12°C, and a hydraulic retention time of approximately 3.3 h. The NH4+ produced by thiocyanate hydrolysis was oxidized by nitrifying bacteria to NO2 and NO3-. The HS- produced by thiocyanate hydrolysis was chemically and biologically oxidized to elemental S, which was subsequently biologically oxidized to sulfate. Incomplete sulfur oxidation occurred in the RBC, particularly at 8°C and elemental sulfur deposition was observed on the RBC disks. The RBC feed exhibited toxicity to rainbow trout but the RBC was effective in removing the acute toxicity of thiocyanate.

Jan 1, 2005

By A. P. Paiva

The solvent extraction properties exhibited by some /V,N'-tetrasubstituted malonamides to efficiently and selectively recover iron(III) from concentrated chloride leaching solutions can be found in the recent literature. The iron(III) extractive chemistry exhibited by some of these derivatives is revisited, in order to compare their chemistry with that shown by a few of the new malonamide compounds. The generally good extraction efficiency towards Fe(III), from >4 M hydrochloric acid solutions, and the relative ease of Fe(III) stripping by distilled water are remarkable findings that are confirmed for the malonamide derivatives described in this work. Furthermore, additional data regarding their selectivity towards Fe(III) extraction over several base metal ions and their behavior when subjected to successive Fe(III) extraction-stripping tests are also presented and discussed.

Jan 1, 2006

By I. I. Bethcherman

Introduction 1.-lmportance of Physical Nature of Condensates The metals of commercial interest which have reasonably high vapour pressures below 1,200° C. are mercury, cadmium, sodium, zinc, magnesium, lithium, and calcium. With the exception of mercury, these metals occupy high positions on the electrochemical series and form compounds with very high negative free-energies of formation. It is highly desirable that such metals should not be produced in a form which is finely divided, on account of their reactivity with atmospheric gases. Powders of magnesium, calcium, and even zinc (blue powder) are dangerous to handle and cannot be coalesced by simple melting techniques. Vaporization in vacuo forms a convenient method of handling and purifying the alkaline earth metals in particular and a previous paper by the authors dealt with some of the factors controlling the separation of metals by this technique (12). An essential part of the operation is the condensation of the vapour to produce a massive deposit which may be conveniently melted and handled by established metallurgical techniques. This investigation sought to determine the conditions affecting the nature of solid condensates.

Jan 1, 1951

By N. Shi, T. G. Joseph

ABSTRACT A revised equilibrium approach to evaluate dipper-ground interactions during the dig cycle of ultra-class mining shovels operating in soft unblasted uniform ground conditions is presented. A review of previous approaches, leading to an outline of the modifications and ground condition considerations, is made in support of the reasoning and basis for the derivation presented. An analytical solution is provided to the scenario of a cable shovel dipper digging in soft ground material such as oil sands.

Jan 1, 2012

By Kazem Oraee

Implementing stable final pit walls in open pit mines during the open pit design phase and mine exploitation has become one of the most important concerns of mining engineers in recent years. Failure of mine walls can potentially cause loss of life, roads blocks, and damage to mining machinery, temporarily or permanently halt production at the face and in the worst case scenario, close the mine. Thus, the role of creating stable mine walls is crucial to safety and general operations of mines and any effort to optimize this process has great economic value for mine operators. This paper aims to illustrate the technical aspects of use of the successful presplit blasting method in metal open pit mines. It also shows that using this approach not only increases safety in mines through wall stabilization, but also will boost economic profits by savings in stripping ratio. In this regard, appropriate practical concepts for designing the drilling and blasting patterns and the role of selecting the correct drilling rigs are elaborated in detail through conducting a case study in Chador Malu iron ore mine in Iran.

Aug 1, 2013