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By S. M. Grillo, M. Fiori, R. Bornioli, C. Marini, S. Fadda

The Na-feldspar orebodies in Sardinia occur along structures belonging to a regional ENE-WSW system that developed during the late stages of the Hercynian orogeny, and that was reactived during the Alpine orogeny. The main petrographic facies include granitoids, albitized granitoids, albitites (more or less rich in quartz), and albitites containing Mg minerals. Field observations and petrological and geochemical data point toward a metasomatic origin for the albitite orebodies. Albitization involved depletion of K from K-feldspar and biotite, dissolution of free quartz, and a lowering of Sr/Na2O and CaO/Na2O ratios in the protolith, under conditions of a positive thermal gradient. The absence of later K-metasomatism implies that, during a subsequent decline in temperature, the composition of the albitizing fuids was modified by an influx of meteoric or other waters. Copyright © 1996 Canadian Institute of Mining, Metallurgy and Petroleum.

Jan 1, 1997

By J. Fellowes, V. Landais, J. Robson, J. Carr

"Aerospace Al-Zn-Mg-Cu (7xxx) alloys are known to be susceptible to environmentally assisted cracking (EAC). This phenomenon has been studied intensively for many decades, leading to empirically adopted methods to mitigate this problem through overaging and composition design. In parallel, many theories have been developed to explain EAC in 7xxx, but none is yet universally accepted. Today, a number of emerging techniques offer potential to shed new light on EAC in 7xxx. The purpose of the present paper is to demonstrate how X-ray tomography (XCT) combined with electron microscopy can be used to identify the true crack path in 3-dimensions, and hence identify material for site specific electron microscopy analysis. Composition mapping over large areas to high accuracy has been performed using a modern electron microprobe analysis system. This has been combined with transmission electron microscopy to investigate local composition in matrix and precipitates at high resolution. This combination of techniques across length scales offers the potential to provide new insights into the links between local composition, microstructure, and EAC resistance.INTRODUCTION Environmentally-assisted cracking (EAC) is a phenomenon which dramatically decreases the performance of metals and can cause premature failure of large structures. Observed in situations where components were not subjected to critical loads and no widespread corrosion was involved, this type of brittle failure is extremely difficult to predict. The EAC designation covers a number of phenomena, e.g. stress corrosion cracking (SCC), hydrogen embrittlement (HE), corrosion fatigue (CF), etc. Initially identified in steels, EAC can also affect other metals such as high-performance aerospace aluminium alloys, and this phenomenon has been a concern for industries for decades. Extensive research has been conducted on the effects of various environments (moist air, saline water, dry hydrogen gas, etc.) on microstructures and crack propagation, however no consensus has been reached and the exact nature of the mechanisms that control EAC is still being debated (Birnbaum & Sofronis, 1994; Gangloff, 2007; Holroyd & Scamans, 2013; Lynch, 2012; Oriani, 1972; Scamans, Alani & Swann, 1976, Young & Scully, 2002)."

Jan 1, 2018

By C. Langer

Although the existence of precious metals, particularly those of the platinum group, in the nickel ores in the Sudbury district has been known for a good many years- almost as long as the ore deposits themselves- the Mond Nickel Company were the first to effect their recovery on a commercial scale. The precious metals values of the different Sudbury ores vary considerably, and are generally higher in the copper-rich ores. These values are so very small that a direct determination in the ores gives quite unreliable results. This is not surprising if one considers that some of the ores contain on1y one unit of total precious metals in about two million units of ore, and that this one unit will consist of seven different metals, each with a different chemical behaviour. It is only after the ores have been smelted to a Bessemer matte containing about 80 per cent combined copper and nickel that the precious metals content can be determined with some degree of certainty. From the figures thus obtained, the precious metals content of the ores can be calculated, provided the tonnage of ore used to produce one ton of matte is known. The recovery of these minute quantities of precious metals out of ?such a large amount of gangue and sulphides of iron, copper, and nickel seems at first glance a commercial and technical impossibility. Nevertheless, science has found a way to conquer all the difficulties, and quite substantial quantities of the precious metals contained in the Sudbury nickel-copper ores have been regu1arly recovered for many years by the Mond Nickel Company.

Jan 1, 1927

By Andreas Gaich

COMBINED 3D IMAGES _ Highly detailed 3D geometry _ Identification of fine fractures together with a general impression of the situation _ Dealing with unfavourable outcrop geometries

May 1, 2009

"Successive seismic waves may cause progressive weakening of a fault zone, which has been recognized as the mechanism of earthquake aftershocks. However, it is unclear that how a fault zone slips under each wave cycle and how slip displacement accumulates under continuous wave cycles. This laboratory study provides direct evidences on the slip process of a simulated granular fault zone dynamically induced by an incident wave without the effects of late-arriving and reflected waves. The experimental observations show forward and backward slip paths of the fault zone and partially recovered slip displacement after a wave incidence. The unrecovered slip displacement after each wave cycle can be accumulated until it reaches a critical slip distance for seismic faulting, which may reinterpret delayed triggering in earthquake dynamics. The limited interseismic period restricts fault self-healing in strength. The experimental results also indicate that the dynamically induced frictional slip on the fault zone is associated with a complex frictional system, including seismic wave radiation, frictional slip initiation and normal stress vibration. Different from the dynamically induced frictional slip on the fault zone, the statically induced frictional slip causes a permanent increase of slip displacement along the shear loading direction. INTRODUCTIONAn earthquake mainshock may induce aftershocks by suddenly changing external stresses applied to another fault zone in the near field (Kilb et al., 2000) and by slightly perturbing a fault zone from a critical steady state to stick-slip faulting in the far field (Gomberg and Davis, 1996). The dynamically induced frictional slip on a fault zone has been recognized as the mechanism of earthquake aftershocks (Marsan and Lengliné, 2008; van der Elst and Brodsky, 2010). Although earthquake aftershocks have been extensively studied by many seismological methods, a simplified laboratory fault zone can provide possible interpretation on real faulting and detailed analysis on a friction process (Dieterich, 1979; Nielsen at al., 2010). According to a few laboratory experiments related to the dynamically induced frictional slip on a simulated fault zone (e.g., Uenishi et al., 1999; Johnson et al., 2012), the slip process induced by successive seismic waves exhibits continuous motions. However, it is unclear that fault slip response under each wave cycle and slip displacement accumulation under continuous wave cycles."

Jan 1, 2015

By J. M. Belland

This paper deals with the geology of the Smallwood mine in relation to its influence on mining and milling operations. Structure within the orebody, and variations in ore grade and material types, will be described and associated with the various drilling, blasting and milling operations. The orientation of planes of weakness, either bedding or jointing planes, and contacts between extremes in material types influence the size of the broken material. Generally speaking, variations in grinding rates and recovery can be associated with stratigraphic sequence and metamorphism.

Jan 1, 1966

By A. C. de Araujo, M. G. Barbosa, R. Martino, S. Gaydardzhiev

The Iron Quadrangle district is a world-class iron ore mining district in the region of Belo Horizonte, capital of Minas Gerais state, in Brazil. Many mining companies have been mining high-grade hematite ores for decades throughout the region. The mines reserves often include itabirite ores which are available in high volumes, but have lower iron grades than hematite ores and require elaborated mineral processing to meet the requirements of downstream steelmaking. Itabirite ores have acquired importance, with the depletion of high-grade hematite reserves due to their intensive mining. The objective of this paper is to propose a geometallurgical model for the processing of itabirite ores from an Iron Quadrangle deposit, which will allow predicting the behaviour of ores throughout the deposit, according to their local variations. An initial step consists in characterizing representative samples of the different ores to acquire mineralogical and textural data. Then, itabirite ores of known characteristics are processed with different techniques, in order to extract the trends and key parameters upon which the geometallurgical model is developed. At first, the model takes into account the particle size distribution and its shift during mining and screening, as well as the chemistry and mineralogy of the material. Then, using the previously identified key parameters such as iron recovery, the model predicts the composition of the processing products. Finally, this data is used to model the mineralogy and mass recovery of the products. The geometallurgical model is of great importance, as it is able to model the processing of any sampled ore throughout the deposit. The incorporation of the results in a mining block model will assist mine planning and opens new opportunities for an optimized mining schedule.

Jan 1, 2016

By Ki-Bok Min, Seokwon Jeon, Seung-Beum Choi, Taehyun Kim

"In order to investigate anisotropic characteristics of Boryeong shale in Korea, which clearly shows transverse isotropy, a series of experimental tests were carried out. Using Brazilian test, five elastic constants and tensile strength of the shale were evaluated. Elastic constants were determined by iterative procedure and in order to perform this procedure, constitutive model was modified to fit the experimental condition. The anisotropic ratios of elastic constants were evaluated and the applicability of the methodology was assessed. Apparent Brazilian tensile strength profile was investigated and the ratio of the maximum to minimum tensile strength was estimated. Results showed that the tested rock type had low to moderate anisotropic characteristics.INTRODUCTIONMechanical, thermal and hydraulic characteristics of many rocks vary according to direction, which is known as inherent anisotropy, and it is originated from stratified and/or foliated structure of intact rock and discontinuity of rock mass. Anisotropy is one of the long standing issues of rock mechanics field and it has to be taken into account in several engineering fields such as civil, mining and petroleum engineering. An anisotropic medium has 21 independent elastic constants without any assumption of symmetry. If a material has any symmetry, the number of elastic constants required to define its behavior reduces and eventually two constants are necessary if it has complete symmetry, which is known as isotropy. An anisotropic medium that has remarkable planar structure due to its stratification and foliation such as bedding is often called as a transversely isotropic medium. Transversely isotropic model is frequently adopted in many applications especially for sedimentary rock formation and five elastic constants are required to establish the constitutive model."

Jan 1, 2015

By A. Saki, P. Gebski, W. Ying

Industrial smelting furnaces are subjected to significant structural changes and deterioration caused by the conditions under which they operate. The current methods for the structural assessment of furnaces include visual inspections, analysis of thermal data, acousto ultrasonic-echo (AU-E) of the refractory lining and surveying of the key structural elements. Acoustic Emission (AE) non-destructive testing (NDT) technique has proven its capabilities for continuous monitoring of industrial installations and structures. Recently, Hatch Ltd. has been successful in applying acoustic emission for monitoring furnace tapblocks, and expanding the scope of the acoustic emission monitoring to the structural integrity of the entire furnace. The capability of detecting emissions related to the fracture development in the furnace shell, movement of the refractory, electrode arcing, combined with efficient source location algorithms makes an acoustic emission system a comprehensive tool for the real-time furnace integrity monitoring. In this paper the concept of such state of the art system for structural integrity assessment is presented. The initial results of the acoustic emission monitoring together with data analysis techniques are discussed.

Jan 1, 2011

By I. Filzwieser, M. B. Hanel, A. Filzwieser

The paper describes the current density increase within the last 150 years. From the beginning in 1885 at 30 A/m² up to the highest used current densities nowadays at 420 A/m² towards future pathways were even 1000 A/m² can be achievable. A short tour through history will highlight the milestones of the process of electrolytic refining of copper. Besides the improvement of the existing technology, the biggest changes leading to higher possible current densities are linked to the introduction of the ISA stainless steel plates and the introduction of the parallel flow principle. Furthermore, the parameters influencing the limitations regarding current density and therefore the practical used current density as well as the influence from the chemical composition of the electrolyte is discussed. Finally, the possibility of further increasing the current densities by enhancing the relative movement between electrolyte and electrode will give an outlook about the future of the copper electrolysis process. INTRODUCTION The current density is the most important characteristic to describe the productivity of a copper refining electrolysis besides the characteristic number for the electrical efficiency. Over the last 150 years, current density has risen from a few amperes per square meter to over 400 A/m² without any significant change in the principle of electrolytic refining. This increase in current density is documented exemplary by the electrolysis of Montanwerke Brixlegg in Austria (Brixlegg, 1963, 2013). The very beginning of the technology of electrolytic refining of copper was first patented in England by James Elkington in 1865 and the first electrolytic copper refinery was built in Newark, New Jersey, in 1883 (Armstrong, 1999). The secondary smelter Montanwerke Brixlegg, Austria, has been operating an electrolysis plant since 1884. In 1988, the third "Mount Isa" electrolysis plant worldwide and the first in Europe was put into operation in Brixlegg. Since 2010, the so-called high-current electrolysis (parallel flow METTOP-BRX Technology) with a current density of approx. 400 A/m² has been operated in half of the electrolysis process.

Jan 1, 2019

By Nirmal Weerasekara

Mill liners serve the dual purpose of protecting the shell from wear and transferring the rotary motion of the mill to an effective grinding action. As the liners wear, the efficiency of energy transfer changes, so there is balance between liner profile for wear and for milling efficiency. A tool that can simultaneously predict the evolution of the liner profile and the associated change in milling efficiency should prove most useful in optimal liner design. This paper presents such an approach, based on measured 3D liner profile data informing 3D DEM simulations of charge motion and liner wear modelling.

Jan 1, 2012

By M. N. Vu, G. Armand, A. Noiret, D. Seyedi

Extensive experimental observations have been performed around drifts and shafts at the Meuse Haute-Marne (North-Eastern France) Underground Research Laboratory (URL) to assess the extent and pattern of the induced fracture networks in Callovo-Oxfordian claystone. Two types of fractures can be distinguished, namely; shear (mode II) and extension unloading (mode I) fractures. The main goal of the present paper is to provide insights on the extent of damaged zone around the drifts by numerical simulations. A two-step approach is considered. First, 2D elastic calculations are performed for simulating the excavation of a drift following the direction of the major in situ horizontal stress. The evolution of the stress and strain tensors around drifts are calculated by applying an elliptic convergence function on the drift wall. Two failure criteria are then verified for the induced damage. An equivalent strain and an elastic energy based damage criteria are considered. The obtained results show that the employed simplified approach provides rather good results for the extent of the damaged zone for drifts parallel to major horizontal stress. However, post-processing elastic results leads to overestimating the vertical extent of the damage zone and underestimating its lateral extent, where the in situ stress state is quasi-isotropic in a section of drift. Nevertheless, the obtained results show that an energy based damage criterion could be considered as a potential way for reproducing the extent of the damaged zones if a convergence function can be defined for the drift.

Jan 1, 2015

By A. K. Alzo?ubi

Block toppling in natural rock slopes has been under investigation since the 1970?s. De Freitas and Watters (1973) introduced the term ?toppling? to describe the movements of rock slopes by rotation in steeply dipping beds. The Lornex pit case history from British Columbia (Canada) was chosen to study the effect of mining on the stability of toppling rock slopes. A discrete element approach that allows fracturing of intact material was applied successfully to model the composite rock slide-rock topple movement. Three main movement modes were observed in the field and the numerical model; the sliding of the top of the slope exposed normal scarps, the toppling at the middle part of the slope exposed obsequent scarps facing opposite to the slope face, and dilation of the rock caused by fracturing at the toe formed loose material. The development of the rupture surface at the toe of the slope was traced and did not evolve into a continuous rupture surface throughout the slope both in the field and the numerical simulation. Good agreement was achieved between the deformations recorded in the field and the numerical simulation.

Jun 1, 2012

By A. J. Rigby

The wear mechanisms of the tuyere lines of Peirce-Smith and Hoboken converters are a subject of endless debate and speculation. However, there has been an indication that one of the primary factors in the deterioration of tuyere lines is due to the batch operation of the converting process. The cooling of the brick in the tuyere line during out-of-stack times leads to shrinkage of the brick and resultant opening of the joints. Subsequently, on re-entry of the tuyere line into the bath, the joints become penetrated with matte and re- expansion of the brick is prevented. It is thought that this regular cycle of exiting the batch for slag skimming and replenishment of matte and re-entering for further blowing leads to a gradual “ratcheting” of the tuyere brick lining. If no expansion allowance is furnished between the endplate and the endwall of the lining, then the generation of damaging compressive stress is unavoidable. INTRODUCTION It is generally accepted industry-wide that the integrity of a refractory lined vessel is determined by an inextricable combination of refractory brick quality, the caliber of the lining design and installation, and the severity of the process inflicted upon the high wear areas of the vessel lining. Rigby has summarized the concentrated attempt, over the past several years, to optimize the microstructural, chemical, and fracture properties of the refractories used in non-ferrous pyrometallurgical vessels. Furthermore, lining design concepts involving larger and longer brick and the extent and positioning of expansion allowance in the joints have been extensively trialed. All these efforts have provided some, but not startling, improvements. The simple fact is that a vessel lining composed of bricks with an optimized microstructure and chemical inertness must installed with a well-conceived design to decompress the lining stresses that are generated by the batch operation of copper converters. REFRACTORY QUALITY Converting is conducted by injecting air into the molten matte and white metal for the very purpose of generating iron and copper oxide slags. These slags must be contained by a refractory which, by its mineralogical formulation, is optimized for chemical inertness.

Jan 1, 2019

By M. E. Holter

"Limestone-bearing strata are exposed in seven areas of Alberta, each situated adjacent to rail and road facilities. Six of these centers are located along the eastern edge of the Foothills and Front Ranges of the Rocky Mountains in western Alberta. The other is in northeastern Alberta, along the eastern margin of the Alberta Basin. High-grade limestones are present in Middle Cambrian, Upper Devonian and Mississippian strata. Middle Cambrian (Eldon Formation) limestones have been exploited only in the Exshaw area west of Calgary, where they formerly were used for lime production. Limestone beds of the Upper Devonian Palliser Formation are exploited at Exshaw and at Cadomin in west-central Alberta for the manufacture of cement. Reserves of high-grade limestone also are available in the Palliser Formation near Crowsnest Lake in southwestern Alberta and near BrUle, west of Edmonton. Upper Devonian limestones of the Waterways Formation are widespread in the Fort McMurray area of northeastern Alberta, but available data indicate they are of inferior quality to the limestone deposits of the Rocky Mountains regions. The Mississippian Livingstone Formation contains large reserves of high-grade limestone at several localities in the Rocky Mountains and Foothills. Commercial development of the unit is now underway at Crowsnest Lake and at Exshaw for lime production, and future exploitation of these beds is feasible at Blairmore and Nordegg."

Jan 1, 1973

By Iain G. Bruce

The need to improve supply reliability while improving our environmental record during the past half decade of low metal prices has required the mining industry to prioritise expenditures. Quantitative Risk Assessments using third party reviewers and specialist risk management teams have assisted in identifying hazards that can both disrupt supply and impact the receiving environment. Graphical displays using risk ellipses can simplify the presentation of the results in a Probability-Consequence (PC) graph. Development of risk acceptability envelopes using readily available financial data superimposed onto the same PC space assists management to prioritise their risks and focus on risk reduction measures. Development of this system and examples of the successful implementation of the system from several recent projects are described.

May 1, 2003

By A. I. Gorshkov, Y. A. Bogdanov, O. Y. Bogdanova

Abstract - Detailed crystal-chemical study of iron and manganese oxides and some other minerals from low-temperature hydrothermal deposits in a newly discovered inactive mound in the TAG hydrothermal field were used to determine the precipitation sequence of mineral phases during lowtemperature processes and their post-sedimentary transformations. Particles of primary sedimentary X-ray amorphous proto-ferrihydrite with high silica content were replaced in situ by nontronite, ferrihydrite, or goethite during alteration. Ferrihydrite is the only proto-hematite phase. The transformation of the iron minerals, related to change in the physicochemical environment, is an important characteristic of low-temperature hydrothermal processes. The occurrence of hydrogenetic Fe vernadite and Mn feroxyhyte in the uppermost part of low-temperature deposits and bottom sediments near the base of the mound is evidence for cessation of low-temperature hydrothermal processes. Among the investigated mineral phases, goethite, nontronite, and hematite are stable in reduced sediments only.

Jan 1, 1999

By Horace Freeman

Introduction This paper is an amplification of the paper presented by the writer at the last (1930) Annual Meeting of the Institute (1), and is somewhat in the nature of a progress report upon the introduction of pyrite into the field of Canadian consumption. The burner installed at the plant of the Canada Power & Paper Corporation, St. Maurice division, has been slightly changed in dimensions and has been put into continuous operation during the past year. As predicted, it has been possible to somewhat increase the steam consumption and at the same time decrease the amount of sulphur remaining in the calcine. The grade of the sulphur-dioxide gas produced has been maintained very steadily at 12 per cent, and sufficient experience has been obtained to determine the renewal cost of continuous operation. The object of this paper now is to encourage the development of pyrite, particularly by-product flotation pyrite, as it is shown that there is a very definite field in Canada for this material and that all the previous objections to the use of pyrite have been overcome, and that the use of the material in practice in paper mills has been developed to such a point that the operation of manufacturing the sulphite cooking-liquor is as simple as, or simpler than, the present style of operation with the use of sulphur.

Jan 1, 1931

By J. T. Birkholzer, M. Rutenberg, K. -H. Lux, R. Wolters, J. Rutqvist, L. Blanco Martin

In this paper, we present numerical results corresponding to the Thermal Simulation for Drift Emplacement (TSDE) test, conducted in the Asse salt mine (Germany) between 1990 and 1999 to simulate reference repository conditions for spent nuclear fuel in rock salt. This test is of significant relevance for nuclear waste disposal in salt because extensive research and measurement programs were set up for the experiment. In our numerical study, we use two sequential simulators, TOUGH-FLAC and FLAC-TOUGH, and we investigate two-way coupled processes, focusing on thermo-mechanical analyses due to the main effect of heating. The two simulators used have recently been updated and are able to deal with large strains and creep processes. Moreover, specific constitutive relationships and coupling functions for rock salt and crushed salt under repository conditions are available. Within the framework of a benchmark exercise between Lawrence Berkeley National Laboratory and Clausthal University of Technology, the same scenario has been modeled in three dimensions using the two simulators mentioned. The main objective of the current, first stage of the benchmark is to evaluate the capabilities of these two simulators to predict relevant processes under repository conditions for high-level nuclear waste in saliniferous media. The comparison of the numerical predictions between them is very satisfactory, leading to a successful code-to-code verification. The comparison between measurements and numerical results shows that the most important processes are captured by the codes and constitutive models used. However, some differences exist between measurements and numerical results. These differences will be addressed in the next stage of the benchmark exercise, in which a parameter fitting effort will be undertaken. Overall, from the results obtained it can be concluded that TOUGH-FLAC and FLAC-TOUGH have the necessary capabilities to reproduce relevant processes under repository conditions for high-level nuclear waste in saliniferous formations.

Jan 1, 2015

By Hrayr Agnerian

The fair market value of an exploration property is determined by its potential to host a mineral deposit. This potential is gauged by the results of previous exploration, exploration stage, meaningful past expenditures and remaining targets that are not yet tested. Values of exploration properties can be viewed as distinct points in a three-dimensional space defined by orthogonal axes, namely: Exploration Stage (x-axis); Cumulative Expenditures (y-axis); and Property Value (z-axis). In general, these values are estimated by applying activity factors on previous exploration expenditures, e.g. an activity factor of 100% for an active property with good potential and a factor of 50% for an active property but past expenditures have not upgraded the property. At certain periods, a market factor may also be applied to reflect the activity of mineral property acquisitions. For properties that do not exhibit any exploration potential, only nominal values are applied.

Jan 1, 1996