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By O. A. Ojo, D. L. Chen, N. Zhou, J. Q. Zhang, A. K. Khan

Dual phase (DP) steels are designed to consist of hard martensite dispersed in a relatively soft ferrite matrix, which offers a favorable combination of high strength with good deformability. Fiber laser welding (FLW) is becoming increasingly important for joining advanced materials due to its flexibility and deep penetration. In this study, the microstructure of a dual phase steel, DP980, welded by FLW technique was carefully analysed. Gleeble thermo-mechanical simulation coupled with analytical transmission electron microscopy (TEM) revealed that the FLW process produced significant microstructural changes in a narrow heat affected zone (HAZ) and fusion zone (FZ), which can result in dramatic changes in mechanical properties. This is reflected in the micro-hardness profile obtained across the welded material. The salient phase transitions induced by the FLW, including the formation of new martensite grains in the upper-critical HAZ and FZ, are discussed.

Jan 1, 2014

By S. Papanakli, Th. Rondoyanni, N. Sabatakakis, K. Kavoura, G. Tsiambaos

"A representative composite fault-related landslide of the Corinth Gulf graben named “Panagopoula” is reported that considered to be one of the most prone to slope instability sites along the main motorway and railway connecting Athens with the city of Patras. The presence of tectonically highly sheared and weathered geological formations, including Alpine basement (mainly flysch) contributes to the site instability, triggered/reactivated by seismic activity and heavy rainfalls. Although a series of remedial measures have been already constructed, the inclinometer readings during the last twenty years time period show a continuous very slow movement which indicates that the landslide is still ""active"". This fact has resulted to divert the axes of the new motorway and railway through twin tunnels which are under construction. INTRODUCTIONThe spatial and temporal evolution of landslides in the case of structurally complex slopes is lithologically and often structurally controlled while their type and frequency are mainly related to tectonic and lithological anisotropy (Baron et al. 2005; Hradecky et al. 2007). The triggering mechanisms mainly include: (a) excessive rainfall generating high pore pressure and (b) strong earthquakes resulting in dynamic loading conditions at the failure surface. Data such as past earthquakes or the precipitation records are useful to be gathered when a landslide model is examined since they could act as a landslide triggering mechanism. Recording of the movement through surface and inclinometer measurements as well as combination of the above information with historical records of failure could lead to a more accurate estimation of the location of the failure surface and understanding of the landslide mechanism.Slope instability in the southern segment of the Gulf of Corinth, Northern Peloponnesus, Greece, is ubiquitous and ranges from deep-seated bedrock failure to secondary earth flows in recent deposits. In this part of Greece, the periodically induced landslide events triggered by heavy rainfall, earthquake and anthropogenic activity are closely related to active fault tectonics. The Gulf of Corinth is considered as a typical example of a relatively simple asymmetric half-graben with major border faults to the south and a flexure of the northern shore. Panagopoula landslide is located along the trace of a WNW trending normal fault (dipping northwards) (Figure 1). The area is considered to be one of those most prone to slope instability along the E95 motorway and railway connecting Athens with the city of Patras."

Jan 1, 2015

By O. Hyvärinen

Outokumpu has developed a new chloride leaching process called HydroCopper®. In this process copper sulfide concentrates are leached at atmospheric pressure in concentrated sodium chloride solution using cupric ions as the oxidant. Copper is recovered from the purified leach solution by precipitating cuprous oxide, which is then reduced to pure copper and further melted and cast directly into copper products. The key reactants: sodium hydroxide, hydrogen and chlorine are generated from the spent sodium chloride using chlor-alkali technology. An important feature in the HydroCopperTM process is that the gold contained in copper concentrates is leached as chloride complexes and recovered from solution by activated carbon. Conditions for the leaching of gold-bearing pyrite can also be achieved in the chloride system by optimizing the redox conditions. This paper deals with the basic factors affecting gold leaching from copper sulfide concentrates. Opportunities for the recovery of refractory gold associated with arsenopyrite and pyrite will also be discussed.

Jan 1, 2005

When selecting a method for monitoring crack growth in pipeline steel, the sensitivity or crack-size resolution plays a dominant role. Even though there are several visual and non-visual methods, the direct current potential drop (DCPD) method is very effective for monitoring crack growth because of its resolution. This method has been used for the past few decades and has gained increasingly wide acceptance in fracture research as one of the most accurate and efficient methods for monitoring the propagation of cracks. Furthermore, most R&D experience has proven that the electrical potential method can be used in most "aggressive" environments. For these reasons, the DCPD method was selected to design a testing machine to monitor corrosion fatigue crack growth. The use of finite-element modelling is shown to facilitate the application of the DCPD method for monitoring crack growth in steels. The 2D model calibration provided a good description of the test data and proved more accurate than the analytic Johnson's formula.

Jan 1, 2005

By H. Kroog

"This contribution reports recent mineral sorting experience and lists the possibilities of the newest generation of automatic mineral sorters with a special focus on electromagnetic detection, optoelectronic technology and the latest innovative X- Ray transmission units. In industry, mineral and ore are still hand-picked and current automation potential is only utilised in a handful of specific applications. Recently a number of technological developments took place that may increase sorting potential, save mill costs and lead to lower overall tonnage costs. The mentioned technologies provide automatic dry separation of minerals and rock as an alternative for conventional processing. The MikroSort technology is environmentally friendly:•,The remaining waste is free of contaminations•,The dump volume is reduced•,The concentration of the high grade material•,at an early stage saves resources"

Jan 1, 2005

By F. J. Macias, A. Bruland, F. E. Dahl

"Tunnelling by use of Tunnel Boring Machine (TBM) is gaining a greater presence as a suitable excavation method. Disc cutter consumption has a strong influence on performance and cost when using TBMs and the influence becomes even more relevant in hard rock. Furthermore, good predictions of TBM performance and cost facilitate the control of risk as well as avoiding delays and budget overruns. Since abrasive wear is the most common process affecting cutter consumption, good laboratory assessments are needed. A new abrasivity test method called Rolling Indentation Abrasion Test was developed. The goal of the new test design and procedure is to reproduce wear behaviour on hard rock tunnel boring in a more realistic way than traditionally used methods by introducing wear by rolling contact on intact rock samples. INTRODUCTIONHigh investments are involved in the tunnelling industry, especially in Tunnel Boring Machines (TBMs) projects. Performance predictions and cost estimations are crucial for planning and risk management of TBM projects. Cutter consumption has a large influence in terms of time and cost, and an even greater effect in case of hard rock projects. Many factors are influencing the amount of cutters consumed in hard rock TBMs. Normal TBM operation results mainly in abrasive wear on the cutters and appropriate methods for abrasivity assessment are needed. Rock abrasiveness cannot be considered as an intrinsic property and the complete tribological system should be considered in addition to the geological properties of the rock.In the present paper, a new test method for abrasivity assessment in tunnel boring called Rolling Indentation Abrasion Test (RIAT) is presented. The traditionally used test methods for determination of rock abrasiveness uses sliding or impact contact in order to cause wear while the RIAT introduces rolling contact on intact rock samples. The ambition of the new test device is to have a reliable method to evaluate the cutter wear in hard rock tunnel boring by reproducing wear behaviour on rolling disc cutters in a more realistic way. It has been established by many authors that the abrasion of a cutter ring is proportional to its rolling distance (Rostami, 1997; Bruland, 1998). In the present work, the weight loss of a mini-cutter ring is measured subsequent to testing in order to evaluate wear in the rolling process and could hence be related to cutter ring wear. Indentation of the tools in the intact rock sample is considered as an indication of the surface hardness of the rock or the resistance to indentation by rolling."

Jan 1, 2015

By Qing-hua Tian, Li-then Cheng, Xue-yi Guo

In order to recycle valuable metals from silver separated residue, a novel method using alkaline smelting at low temperature was proposed. The main factors affecting the main metal recovery such as the smelting temperature, smelting time, liquid-to-solid ratio and alkali addition were investigated comprehensively. The behavior of the main metal elements, such as Pb, Sn, Sb and Bi in silver separated residue was also discussed. The results indicated that amphoteric metals such as Pb and Sn can be smelted into the melt, while other metal elements, such as Sb and Bi were left in the residue.

Jan 1, 2011

By M. Mirzazadeh

Air cooled crackable and conventional forged steel specimens were tested under reversed push-pull conditions to examine the effect of shot-peening on their high cycle fatigue behaviour (-106 cycles). The steels were tested in the normalized as well as shot-peened conditions. The results showed that shot-peening smooth specimens had little effect on the fatigue limit of the air cooled forged steels and the detrimental effect of the rougher peened surface was not apparent. Microhardness profiles indicated that the shot peening produced a gradient of compressive residual stresses that was greater than that of the loading stresses, suppressing the anticipated beneficial effect on fatigue life. Crack initiation was more likely to occur below the surface. The results indicate that the surface roughness was not a significant factor in controlling the fatigue lives, since they were essentially the same for the non shot-peened and shot-peened steels.

Jan 1, 2010

By T. G. Joseph

ABSTRACT: The Canadian oil sands provide some of the harshest mining conditions in the world. Asoperations demand ever bigger tools, the toll on large mobile mining equipment is high, with structural life often half of that expected. Soft ground conditions predominantly lead to fatigue failure scenarios, poor stability, and inconsistent payload evaluations. These challenges are not solely a concern for Canadian oil sands mines; there are far-reaching implications for surface mining equipment in any poor ground-operating environment. This paper focuses on the basics of payload evaluation, motion response, and a simple estimate of structural life for haulers.

Jan 1, 2011

By D. Michaud, C. Bazin, S. Lévesque, L. Pérez-Barnuevo, H. Longuepée

In recent years, with the emergence of Geometallurgy, a great effort has been made to characterize ore resources as early and accurately as possible, to allow better design and a more efficient operation of mineral processing circuits. In this context, core logging plays an important role, since drill cores provide the first insight into the ore characteristics. However, to satisfy geometallurgical requirements, traditional core logging does not suffice. New tools and methodologies need to be developed for the automation of core logging and the acquisition of mineralogical data better related to mineral processing performances. In this paper, a methodology for the geometallurgical characterization of drill cores is proposed, based on the drill core textural patterns. Textural pattern is defined here as the macroscopic spatial arrangement of minerals. The Mont-Wright iron ore deposit (Quebec, Canada) is used as a case study. The first part of this work aimed at analyzing the potential link between the iron ores textural patterns observed in drill cores and their response to ore processing, namely comminution and concentration. Preliminary results show similar performances in terms of energy consumption and heavy liquid separation for samples showing the same textural pattern. In the second part, this work seeks to develop a methodology for the automated identification of drill core textural patterns by the application of digital image analysis and discriminant function analysis. The results obtained show that this methodology is able to discriminate between the textural patterns identified at Mont-Wright with a good rate of success. Therefore, this work lays the foundation for the development of a new drill core characterization tool, which would allow for the early prediction of the iron ore behaviour during mineral processing through the identification of drill core textural patterns.

Jan 1, 2016

By I. M. R. Duarte, J. A. Rodrigues-Carvalho, F. R. S. Rosa, A. B. Pinho

"This paper aims to contribute to the knowledge of the mechanical properties of the shales and greywackes which constitute the flysch-type deposits of the Baixo Alentejo Flysch Group, in the south of Portugal. These formations are flysch-type deposits constituted by sequences of usually thick greywacke beds alternating with thin shale beds, which include sometimes intercalations of conglomerate beds. All the sedimentation of these flysch formations was controlled by tectonics. At the same time, should have occurred along with the first Hercynian deformation phase, a low-grade metamorphic event (chlorite zone), that affected these flysch deposits. This study highlights the influence of anisotropy and heterogeneity of these flysch rocks on their physical and mechanical characteristics. The anisotropy verified in some physical properties and on mechanical properties, due to the foliation makes difficult the sample preparation for the laboratory tests. Besides, it induces a scattering of the properties values measured, as for example, the strength and the deformability. The heterogeneity is related to the main features of these geological formations, which are constituted mostly by thinly stratified greywackes and shale beds, which sometimes may affect the results of the laboratory tests making them less representative. The study is made by using both shales and greywackes that constitute these flysch-type deposits in order to evaluate their geotechnical properties, mainly of the shales. Samples of these two rock materials, are tested accordingly a laboratory testing programme, which includes which included mineralogical analysis (X-ray diffraction), physical tests (bulk density, porosity, and void index) and mechanical tests (uniaxial compression, and deformability tests). INTRODUCTIONOne of the factors that most influence the geomechanical behavior of rocks, as well as rock masses is the anisotropy. The word anisotropy comes from two Greek words ""anisos"" (meaning uneven) and ""tropos"" (meaning direction). A body or material is considered to be anisotropic, where the same property has different values depending in which direction it is measured, therefore, an anisotropic material is one whose magnitude of the properties depends on the direction in which these are studied or measured. Otherwise, it is about an isotropic material. However, the fully isotropic materials are quite rare in nature."

Jan 1, 2015

By Louis Frost

MINE ventilation has for many years been the subject of intensive study by numerous investigators who have presented their findings in forms that are understandable to the average mining man, and all this writer hopes to do is to review those findings in relation to the 'manager's' problem in mine ventilation. It would not, perhaps, be wholly correct to acclaim practical mine ventilation as an exact science, because of the many variables entering into the problem. Each mine has its own particular problem and ventilation characteristics. Fan design, in contra distinction to mine ventilation, is an exact science, but the designer cannot always take into proper consideration the practical variations to which each mine is subject. Fan designers, accordingly, are forced to base their design on such data as the mine manager or engineer is able to supply, and, when it is borne in mind that the mine characteristic is constantly changing, it is not at all surprising that fans do not always show efficiencies hoped for. In many instances, fans work far beyond the de-signer's limitations, and, in consequence, are an economic disability in the colliery cost-sheet, and it is of paramount importance that the colliery manager evaluate all the factors involved in relation to fan performance for the colliery to receive full benefit from its investment.

Jan 1, 1941

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 J. Font

The RAF or copper fire refining process at the Caletones smelter of CodelcoChile consists of several pyrorefining stages that successively lowers the levels of S, Fe, Pb, As, Sb, Te, Se and to some extent 0 in the copper melt, allowing the production of high quality fire-refined copper of 99.93 % purity (RAF copper). This chemical feature of the RAF copper is only achieved by quite long processing times, and a considerable consumption of fluxes and fuels in the RAF vessels. The main goal of this study was to improve the RAF process performance by thermodynamic considerations and industrial scale tests, i.e., an in situ approach for the process as featured by intensive sampling, characterization and subsequent modifications. Thus, both theoretical and industrial data were derived, and based on kinetic and thermodynamic evaluations, a higher operational standard was achieved for the RAF process. These new operational practices allowed enhancing the overall economic of the RAF process, by reducing the time and operational costs, and consequently increasing the availability of the vessels.

Jan 1, 2007

By John Taylor

"The Highvale Mine in Alberta is owned by TransAlta Utilities Corpora/ion and operated by Mana/fa Coal Lid. It is the largest coal mine in Canada and in 1982 supplied 8.6 million 1onnes of sub-bituminous ""B"" coal to TransAlta's Sundance Ceneraling Plan/. Annual produclion is scheduled to increase in 1983 when the firs/ unit of the new Keephil/s Generating Plant comes on stream and is expec/ed to exceed 11 million tonnes by 1985 when the second unit is commissioned. Coal is mined from several pits in a multi-seam operation. Comprehensive maintenance, drainage and environmental programs form a major part of the operation.IntroductionThe Highvale Mine is located eighty kilometres west of Edmonton, Alberta on the south shore of Lake Wabamun (Fig. I). The mine is owned by TransAlta Utilities Corporation (T.A.U.) and is operated by Manalta Coal Ltd. In 1982, 8.6 million tonnes of coal were supplied to T.A.U.'s 2100 MW Sundance Generating Plant, making it the largest producing coal mine in Canada. By 1985, with two 375 MW units on line at T.A. U .'s new Keephills Generating Plant, annual production is estimated to exceed eleven million tonnes. The generating plants accept crushed unwashed coal from the mine via the coal handling plant system conveyor belts. The coal is classified as sub-bituminous ""B"" and has an average heating capacity of 18.6 MJ I kg.HistoryPrior to 1943 only small scale mining took place in the Highvale area. Between 1943 and 1961 two strip mining companies, Mount Royal Collieries and Continental Collieries operated on the present mine site. Both operations excavated coal along the south shore of Lake Wabamun."

Jan 1, 1985

By Matthew Violot

Vale Canada?s Birchtree Mine, located in Thompson Manitoba, has been experiencing problems with hanging wall / footwall dilution, as well as sloughing off of adjacent stopes and temporary stope block backs. Birchtree Mine is interested in determining how time affects the stability of their open stope blocks. Many factors simultaneously influence open stope stability (rock mass quality, joint condition, stress condition). This makes it challenging to determine the influence of a single parameter such as exposure time or stand-up time. This study focuses on determining the effect of exposure time on open stope dilution and combines stress analysis and empirical based approaches.

Jun 1, 2012

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 M. Pierce

Empirical relations exist for the estimation of rock block strength at scales larger than standard core sizes. Two recently published relations account for the significant impact that microflaws (pores, open cracks, veins) and weathering/alteration can have on scale effect. These relations were used to estimate the rock block strength of heavily microfractured quartzite from the Bingham Canyon Mine. Predictions were compared to the results of Uniaxial Compressive Strength (UCS) tests conducted on cylindrical core samples of varying microfracture intensity and diameter. The comparison confirms the sensitivity to microfracturing suggested by existing relations and suggests that they would benefit from more detailed consideration of microfracture strength, density and persistence over a range of scales. The results of a numerical study illustrate how Synthetic Rock Mass (SRM) modeling techniques could be used to complement empirical data in the development of such relations.

May 1, 2009

By H. Thalenhorst

For an advanced mineral exploration project that has a ?nugget? issue making the assessment of the deposit grade difficult, a bulk sampling program using a sample tower can provide information that is otherwise not obtainable prior to actual production. This information includes the verification of predicted resource grades for the bulk sample tonnage (and, indirectly, of the methods and parameters used for the grade estimate), confirmation of the physical and grade continuity of the mineralization, and geotechnical data for a future mining operation. The information gathered will improve the input of a feasibility study, particularly with respect to expected mining grades, which are the key economic parameter for most mining projects. The bulk sample rejects can be used for pilotscale metallurgical testwork. Bulk sampling is also useful in cases of potentially biased drill-hole assay results and in the reliable determination of ore grade before shipment of ore from production or development operations to an external beneficiation plant. This paper presents a practical bulk sampling and sample preparation protocol, lists design features for the sample tower, examines the sampling errors that will be encountered, provides information on quality control procedures, and looks at the costs and benefits of such a program, based on the experience of undertaking bulk sampling programs during the period of 1985 to 2008.

May 1, 2010

RÉSUMÉ L’estimation la plus précise possible des coûts de minage est d’extrême importance pour les études de préfaisabilité afin de diminuer les risques financiers des projets miniers. Les méthodologies existantes d’évaluation des coûts de minage ne permettent pas de les évaluer avec des marges d’erreur acceptables tout au long de l’évolution des projets miniers. Elles visent à évaluer les coûts unitaires de minage des études préliminaires de faisabilité, pour les principales méthodes d’exploitation, en prenant pour l’hypothèse que ces coûts dépendent principalement du taux d’extraction journalière. Si cette hypothèse peut être justifiée pour l’évaluation du coût d’opération, elle est fort discutable pour l’évaluation des coûts de minage. Pour démontrer que cette hypothèse est inadéquate nous avons analysé la méthode d’exploitation la plus populaire sur le continent nord-américain c’est à dire celle par chambres vides avec retrait horizontal (Hr – Horizontal retreat), ou « Longhole » et celle avec retrait vertical (VCr - Vertical Crater retreat). Il ressort de cette analyse que les coûts unitaires de minage dépendent principalement des conditions géotechniques du massif rocheux et de la largeur du gisement et non pas du taux d’extraction journalière du minerai.

Jan 1, 2010