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By Denis J. Kemp

The 20th Century saw changes in the mining and metallurgical industry not only technically but also in social and environmental expectations. As projects continue to become larger to maintain competitiveness the visibility of their potential impacts raise concerns among many groups. The need for transparency, openness and early engagement of all parties are fundamental to assure success. An equally important task is to anticipate the standards that will be required to meet society?s expectations in the 21st Century. Historical Observations The mining industry of the 18 and 19th Century was dominated by opportunistic Companies and individuals with an entrepreneurial flair for adventure and risk. Those who promoted had the chance of great reward, while those willing to risk their life were assured a short one for their efforts because of the physical and health dangers that abounded. Disregarding conditions miners rewards were high even in those days, with an average Cornish miner known to be earning two pound a month in 1800. Coal and iron ore mines were driven by the needs of the industrial revolution and were the first to embark on larger scale output. Base metal mines were smaller as industrial demands for their use did not start to expand greatly till the late 19th Century. Electrification, the automobile and the 1st World War drove the increased demand for a variety of metals. Early mines were foul smelling and dusty and what was taken from below ground left spoil piles around the surface countryside after recovery of the coal or concentrate. The image of barren blackened hills is one that is easily conjured up and is an environmental legacy that still lives with us today.

May 1, 2002

By T. T. Chen, J. E. Dutrizac, G. Poirier

In the Waelz kiln process, EAF dust is converted to an Fe-rich slag, a (Zn, Fe)-rich dust that is recycled to the kiln and the Zn-rich Waelz oxide which is subsequently up-graded for the recovery of zinc. To clarify the reactions occurring, the Waelz kiln products from a European Waelz plant were characterized mineralogically to determine the mineral species present, their micro-textures and the metal carriers. The EAF dust contains 27 % Zn, and consists mainly of ZnFe2O4 and ZnO, together with minor to trace amounts of NaCl, PbCl2, KCl, CaO, Ca2Fe2O5, Fe203, FRO, Pb oxide and various Ca-Fe-Al-Mn silicates. The KCI and NaCI sometimes agglomerate the other particles. The slag consists of nodules which often exhibit colloform structures. The slag contains of variable amounts of Fe, FeO(OH), FeO, gypsum, Ca(OH)2, Ca2SiO4 and various Ca-Fe¬Al-Mg-Mn silicates as well as minor to trace amounts of ZnFe2O4, Cr-Fe oxide, Mn-Fe oxide and other species. The Waelz oxide contains 57-61 % Zn, and consists predominantly of ZnO, with minor to trace amounts of KCI NaCl, Pb(OH)Cl, Pb20(SO4), Pb chloride, ZnSO4, ZnFe2O4, Ca2SiO4, Ca2Fe2O5, Ca-Fe silicate and NaZn4(SO4)(OH)6Cl.6H2O. The KCI agglomerates the other particles in the Waelz oxide. The recycled dust appears to be a mixture of EAF dust and Waelz oxide, but it contains relatively more coarser-grained metallic Pb and Pb oxide particles.

Jan 1, 2004

By H. C. Cooke

"The Part of the Eastern Townships dealt with in this paper is shown in the accompanying figure. Each rectangle represents one of the topographic maps published by the Department of National Defence on a scale of one mile to one inch. Each sheet covers an area approximately 24 miles long and 17 miles wide, or slightly more than 400 square miles. The north-western part of the area figured, comprising the Upton, Aston, Becancour, and the two unnamed sheets, (Three Rivers and Yamaska), together with most of the Lyster, Drummondville, and St. Hyacinthe sheets, is largely covered by clays and sands deposited in interglacial and post-glacial time in the Champlain estuary, so that outcrops are widely scattered and in-formation is correspondingly sketchy. In the remainder of the area figured, comprising more than 4,000 square miles, outcrops are reasonably numerous and have been mapped on a scale of one mile to one inch, and the structure is moderately well understood.The Eastern Townships was an area of intense orogenic disturbance, apparently beginning late in the Cambrian or early in the Ordovician, and continuing till well on in the Devonian period. During this long period, which may have lasted for a hundred million years or more, the area was subjected from time to time to intense thrusts from the east and southeast. Each of these caused folding of the rocks, accompanied by faulting, raised parts of the area above sea-level, and presumably created ranges of mountains. Long periods of erosion cut away the mountains and reduced the area nearly to sea-level after which subsidence carried it below sea-level, and permitted further sediments to accumulate before the next thrust initiated the next cycle.The first of these movements, as stated, appears to have been in late Cambrian or early Ordovician time. The group of rocks known as Caldwell was folded and, south and east of the town of Asbestos, was thrown into great drag-folds before deposition of the next overlying series, termed the Beauceville, began. Unfortunately, the date of this orogeny is very imperfectly known, because both series of rocks have been so crushed and sheared that almost all fossil remains have been destroyed. Graptolites, found in one place in slates generally considered Beauceville, give that series a tentative Middle Ordovician age. In the Caldwell rocks, which underlie the Beauceville with great unconformity, no fossils whatever have yet been found. Thus, if the Beauceville rocks are correctly dated as mid-Ordovician, the best that can be said of the movement folding the Caldwell is that it took place at some time before Middle Ordovician."

Jan 1, 1949

By J. W. Reynolds

This paper describes the function of the research and development department of a large mining organization and the benefits which can be derived over the years. Examples are given of work done in rock drilling, ventilation, noise control and the development of backfill stowing machinery.

Jan 1, 1970

By Martin Irving

Adding Value to Canadian Diamonds - A Changing Diamond Industry - Diamond Mining - Diamond Manufacturing - Diamond Jewellery Markets - NWT Diamonds Changing Diamond Industry - De Beers ? privatization - Oppenheimers (45%), Anglo-American (45%), Botswana (10%) ? going retail - LVMH joint venture - New Players ? jurisdictions - Canada ? companies - BHP-Billiton - Aber Diamonds

May 1, 2002

By Y. -B. Kang

New databases are being developed to provide the capability to evaluate the suitability of present and potential new Mg alloys for automotive applications through cost-effective calculations. An extensive and complete thermodynamic database is being prepared for Mg alloys formed from among 25 present and potential alloying elements. The database is being developed by critical evaluation, modeling and optimization of available phase equilibrium and thermodynamic data. It contains model parameters giving the thermodynamic properties as functions of temperature and composition. Using the FactSage thermodynamic software, users can access the database to calculate the amounts and compositions of all phases at equilibrium at any temperature and composition or to calculate any phase diagram section in multicomponent alloys, to follow the course of equilibrium or non-equilibrium cooling, to calculate corresponding heat effects, etc. A database of densities and lattice parameters of Mg alloys and intermetallics (as functions of temperature and composition) is also being developed in order to permit the calculation of volume changes during cooling and phase transformations, c/a ratios of the hcp phase, etc.

Jan 1, 2006

By Amin Jafari

Macrosegregation has always been an important issue with the solidification processes, particularly in Direct-Chill Casting of Aluminum alloys, where uneven properties, surface and bulk defects and limitations in productivity can be arisen due to macrosegregation in the cast product. Following the global attempts to practically predict the macrosegregation, in the present work, a numerical model was developed based on an industrial scale DC casting process to simulate the solidification and macrosegregation in an Al-4.5%Cu billet. Interesting aspects of this investigation are concerned with an efficient numerical scheme to keep simplicity, consistency and desired physical resolution of the solidification phenomena together. In the mathematical model, coupled conservation equations of mass, momentum, energy and species were solved numerically using finite volume method. A different numerical scheme, called SIMTLE, was introduced to link the energy and species equations with the phase diagram of the alloy. Calculations were performed on an industrial case and obtained results were compared to available experimental data to assure the performance of the model. Different macrosegregation features were predicted and discussed on the solidifying Al-alloy billet.

Oct 1, 2011

By M. C. Bluteau, G. P. Demopoulos

Arsenic reports in the effluents of many non-ferrous metallurgical operations. The production of scorodite, a crystalline ferric arsenate, is considered as an attractive option for the fixation of arsenic from aqueous effluents. However, scorodite solubility and long-term stability in the pH region of interest for tailings disposal have not been thoroughly investigated. In this study the long-term stability of scorodite in the pH 5 to 9 region and the mechanism of scorodite dissolution were studied. Construction of eh-pH diagrams indicated that scorodite stability is highly dependant on the nature (stability) of co-existing iron-hydroxide/oxyhydroxide. It was also found that when scorodite dissolves, a ferrihydrite phase having very small particles size (nano-scale) forms and that the growth and crystallization of this material are delayed by the presence of arsenate even under accelerated (75°C) ageing conditions. Around neutral pH and ambiant temperature (22°C) scorodite seems to reach an equilibrium with ferrihydrite after 48 weeks yielding soluble arsenic concentrations < 5 ppm.

Jan 1, 2004

By L. Cifuentes

The temperature dependence of: a) electrolyte density, viscosity and electrical conductivity and b) the equilibrium constants of formation for all relevant species have been determined as part of an effort to model the operation of a copper electrowinning cell based on reactive electrodialysis. The studied ranges were: 1.01 to 1.25 g/cm3 for density, 4.9x10-4 to 16.4x10-4 kg m-1 s-1 for viscosity and 0.02 to 86.0 Sri m-1 for electrical conductivity. Density and the electrical conductivity of the catholyte increased linearly with temperature whereas the viscosity increase was exponential. The main effect of ionic speciation was to decrease the electrical conductivity with increasing metal concentration due to ion association (mainly the formation of bisulphate ion) which lowered the concentration of protons (the most mobile species) in solution. This effect was specially noticeable in the anolyte. Mathematical relationships with correlation coefficients between 0.959 and 1.000 have been found for all the studied variables.

Jan 1, 2007

Despite the claims of energy efficiency and the considerable development that has gone into dramatically extending rolls’ life and facilitating rolls’ change-out, in the six years since the last SAG conference, only a few HPGR operations have entered the realm of mineral processing. Risk barriers to the take-up of new equipment or processes are: a massive increase in materials handling issues as well as in the number of pieces of equipment required, low total circuit potential energy savings, and similar or higher capital costs. An alternative route is to make use of the complementary strengths of the HPGR and SAG in hybrid circuits. Minimising materials handling issues, providing an ideal balanced feed to the AG or SAG mill, and improving controllability through shifting grinding load as the RoM feed changes, are all potential major advantages to this approach. Conceptual circuit layouts, based on real measured ore and equipment data, are presented here to illustrate the potential production upside, the reduction in operating costs and the reduction in the physical and energy footprints.

Jan 1, 2012

By . A. C. Atenas

Control of arsenic in the Potrerillos&apos; Refinery electrolyte has been obtained by withdrawing a bleed stream of circulating electrolyte and ensuring the ratio of [O]/[As] in the cast anodes is maintained between 0.9 and 1.0. In order to achieve this control the anode oxygen must be adjusted, depending on the arsenic level in the cast anodes. It has been necessary to modify the time of the reduction step in the anode furnace refining process. Control of this ratio has permitted electro refining of anodes with high levels of arsenic, up to 3000 ppm, while minimizing the volume of electrolyte that must be removed for impurity control so as not to affect the copper concentration in the electrolyte. However this control strategy is not useful when the arsenic concentration in the cast anode is too high, because it is limited by the maximum oxygen concentration allowable for a good quality anodic. Costs have been reduced in anode furnace refining because it is no longer necessary to use alkaline flux injection to remove the arsenic in cast anodes.

Jan 1, 2007

By K. Morikawa, K. Asano, J. Yoshitomi

The quality requirements for ladle shrouds have become stricter year by year to the pursuit of higher productivity and improved quality in the continuous casting of steel. The ladle shrouds must be sufficiently durable under severe conditions, such as operation without preheating and during several sequential castings. The consideration is that ceramic fibres, which have been applied in shrouds for thermal insulation during casting, could pose a risk to the worker&apos;s health. We realized materials for the ladle shrouds which show high strength and low elasticity. At the same time pursuing effective insulation, a coating which contains no fibres (Foaming Coat) has been developed, replacing the conventional one containing fibres. These materials are durable under conditions of repetitive use and consequently satisfy the customer&apos;s demands. The ladle shrouds which were improved in this way have achieved an excellent durable life in hot service of three times that of conventional ones. This paper reports the recent technological developments in ladle shrouds as well as their performance under hot operating conditions.

Jan 1, 2004

By R. V. Kumar, F. Tailoka

In order to use ZnO laden dust as a possible desulphurization reagent, it is important to evaluate thermodynamics of the Zn-O-S system. At temperatures greater than 1450 K, there is an uncertainty in the thermodynamic data for the reaction of zinc with sulfur to form Zinc sulfide. In this work, the standard free energy has been determined using an electrochemical cell: Pt, Mo, MoO2/YSZ/ZnO, ZnS, S02, Pt., between 1198 and 1602 K. AG° varies from -145,880 to -88,100 J (± 2500) , with a phase change to ZnS (g) by sublimation occurring between 1450 and 1460 K. This is supported by thermogravimetric analysis which shows about 80% weight loss in ZnS from 1273 to 1473 K. Feasibility reactions were also performed and confirmed that ZnS (g) is formed when ZnO reacts with FeS (1473 to 1653 K) or with Fe-Csat-S(1473-1673 K). There is therefore potential for the utilization of ZnO laden waste as an additional or alternative reagent for desulfurisation.

Jan 1, 2004

By T. Cutard, E. Yeugo Fogaing, C. Gault, H. Marzagui, N. Prompt, M. Huger, C. Deteuf

This paper deals with studies made in the field of the French research network PROMETHEREF. Several refractory castables are considered in this program. In the present paper, one of these materials is considered, it is a low cement castable based on andalusite aggregates. A particular attention is paid to microstructural changes during the first heating and on their effects on the high temperature mechanical behavior. Microstructural evolutions have been characterized by the way of dilatometry, scanning electron microcopy and X-ray diffraction. In-situ observations by environmental scanning electron microscopy gave complementary results on these high temperature microstructural changes. They deal with microcrack formation, phase changes, crystallization, liquid phase formation and sintering. By propagation of ultrasonic waves, high temperature continuous measurements of the Young&apos;s modulus have been made. Results confirm the existence of microstructural changes and allow to quantify the Young&apos;s modulus variations all along specific thermal cycles. High temperature four point bending tests and room temperature tensile tests were made in the same temperature range. Behavior evolutions could be found and interpreted with the help of previously mentioned results.

Jan 1, 2004

By M. Mahdi Aboutalebi, Roderick I. L. Guthrie, Mihaiela Isac

"A preliminary computational fluid flow model has been developed to simulate the flow field of liquid steel in the mold region of billet mold casting. This study reports the effect of different Submerged Entry Nozzles (SEN) on the fluid flow in round and square billet, curved mold, casters. In this study, ANSYS Fluent 14.5 software was used to model the 3-D turbulent flow of liquid steel. The standard k-0 model was used to simulate turbulence in the mold region. Similarly, the species transport equations were discretized to simulate the dye injection test into the mold cavity. The behavior of flow in the mold region was validated against previous experimental work. Predicted results showed that different nozzle types plus the slight curvatures in the molds can significantly influence the flow patterns generated within the mold region, and thereby affect the finished quality of the billet products.INTRODUCTIONConventional Continuous Casting (C.C) processes are presently used to solidify more than 95% of the 1.5 billion tons of steel now produced in the world annually (World Steel in Figure, 2014). This overwhelming contribution of C.C processes for steel production is the prime motivation for this study, in order to understand and optimize the casting processes and thereby reduce internal defects and minimize energy consumption. The primary objective of all C.C processes is to maintain liquid metal purity during the casting process and to create a uniform flow within the caster so as to avoid internal and external defects. In this regard, studying fluid flows in the mold region of continuous caster has attracted many research groups, in both academia and industry, in recent years. The mold region is one of the most critical parts of the C.C. process, in which the transport phenomena associated with this region can significantly affect the quality of the final products. Thus, proper control of fluid flows within this region can be expected to greatly decrease both internal and surface defects such as Oscillation Marks (OM), inclusion entrapment, and Mold Powder Entrapment (MPE). In the casting process, the fluid flow in the mold region can be affected by a number of variables, such as; the flow control system (stopper rod or slide gate), nozzle geometry, SEN (Submerged Entry Nozzle) depth, casting speed, mold dimensions, gas injection, and the application of electromagnetic fields. One of the most influential and easily-changed fluid flows are the jets of steel issuing from the SEN. Nozzle geometries are variable, consisting of a number of exit ports, different port angles, and/or port sizes, the bottom shape of the nozzle, and the SEN immersion depth (Thomas, 2001). The SEN characteristics can markedly affect meniscus surface velocities, surface level profiles, and turbulence levels that can vary in terms of the frequency and the magnitude of their fluctuations."

Jan 1, 2016

By Fernando Canales

In the last decade a great dealt of attention has been paid to the chemistry of polynuclear gold derivatives with a central heteroatom, not only from the experimental and structural but also from the theoretical standpoint (1). Interesting hypercoordinated species of the type [C(AuPR3)5]+, [C(AuPR3)6]2+, [N(AuPR3)5]2+, [P(AuPR3)5]2+ and [P(AuPR3)6]3+ have been described (2), apart from other complexes with more conventional stoichiometry, and all have in common the presence of gold-gold interactions of ca. 3 Å. Usually, the chemistry of the first row elements of the p-block is known to follow classical rules of bonding, and only in cases of extreme electron-deficiency has the traditional electron count to be reconsidered to account for special types of molecular or solid state structures. Many of these heteroatomcentered complexes are electron-deficient and the gold-gold interactions provide a significant contribution to their stability. The attraction between these closed-shell systems has recently captured the attention in inorganic and organometallic chemistry (1). P. Pyykkö has summarized the available theoretical and experimental evidence of intra- and inter-molecular interactions between heavy metal atoms, such as Au(I) (3). In general, when heavy metals are involved in such interaction, the closed-shell attractions are of metallophilic or van der Waals type, as has been found for d8, d10 coinage-metals, and d10s2 centers. Experimental evidence for the aurophilic Au(I)???Au(I) attraction is available from crystallography, NMR and Raman spectroscopies, and optical spectroscopic measurements of the interaction strength (4). It is manifested in molecular conformations with relatively close Au???Au interactions of ca. 3 Å, whose strength has been estimated at ca. 25-50 kJ/mol (5). These attractions are weaker than most covalent or ionic bonds, but stronger than other van der Waals bonds and comparable in strength to typical hydrogen bonds. The phenomenon cannot be satisfactorily explained by classical theories such as hybridization (3). From a theoretical point of view, the attractions close to equilibrium distances are caused by dispersive interactions together with relativistic effects (6). The attractive contributions are dominated by pair-excitations from the heavy metal, such as gold, strengthened by relativistic effects. In all the cases where there are inter- or intramolecular metal-metal attractions, the correlation effects are essential; if they are omitted, at the Hartree-Fock (HF) level, repulsive interactions are obtained (6). Hence, it is necessary to use at least second-order Møller-Plesset level (MP2) methods for the dispersive forces, which are included in the electronic correlation effects (7).

Oct 1, 2003

By Poul Hansen

"In mid-1986, a world-class mining enterprise was created in Highland Valley, British Columbia, bringing together the copper mining operations of Lomex and Cominco . In 1988, Highmont joined the new partnership.Highland Valley Copper is the largest copper mine in North America in terms of both tonnage mined and tonnage milled, and it is one of the largest in the world. Due to its relatively low ore grade its production of copper in concentrate ranks about ninth in the Western World.The current eighteen year mine plan is based on ore reserves of 761 million tonnes. The daily milling rate is 133 000 tonnes. At the end of mine life, a total area of approximately 6500 hectares will have been disturbed. At this time, vegetation has been established on about 600 hectares and while work will be done during the operating years, it will not be until the end of mine life, about 2008, that the last half of the land can be reclaimed and revegetated.Once final reclamation has been accomplished, Highland Valley Copper will have completed its "" temporary use of the land"". In the meantime, about 1250people have had employment for about 50 000 man years, at wages ranking among the best in Canada.IntroductionTo provide and sustain our way of life, we need steel, copper, aluminum, zinc and many other minerals.To sustain mining, we must have adequate ore reserves and replacement of reserves as they are mined. Each year the search becomes more difficult as more of the Earth&apos;s surface is investigated and depo sits are mined. This calls for aggressive and sustained efforts.In British Columbia, past and present mining activities have disturbed less than one-tenth of one per cent of the land.With today’s technology, mining operations can be substantially reclaimed and thus complete the cycle of ""A Temporary Use of the Land""."

Jan 1, 1992

By Andrea R. Gerson, Roger St. C. Smart, Russell Schumann, Joan E. Thomas, Warwick Stewart, Stuart Miller

Sequential Net Acid Generation (NAG) accelerated oxidation testing using peroxide was carried out on single sulfide mineral samples. The calculation of the nett acid production potential (NAPP) assumes that all the sulfide is present as pyrite and that dissolution results in a 2:1 ratio of H+:SO42-. NAPP as kg H2SO4/t is calculated as 30.6 x wt.% S present. To test whether this calculation is valid a NAPP* value was defined in which instead of using the wt.% S present for the calculation the wt.% S dissolved is used. Stoichiometric analysis of the dissolution products of the sulfide minerals as they would occur at pH 7 indicates, that in all cases, the ratio of H+:SO42- of 2:1 is viable. The NAG to pH 7 and NAPP* closely coincided for pyrite, bornite, chalcocite and covellite. For the three Cu-containing minerals, the NAG to pH 4.5 value was 0 as is predicted on the basis of the speciation likely to be present at pH 4.5. Acid generation is due to hydroxylation of the dissolved Cu between pH 4.5 and 7.0. The NAG to pH 7 and NAPP* values for chalcopyrite, arsenopyrite and pyrrhotite were in reasonable agreement but were not for either sphalerite or galena. Zn is not completely hydroxylated at pH 7 as is assumed by the calculation. For galena, surface analysis identified polysulfide formation on of the leach residue polysulfide. The formation of polysulfide is an acid consuming reaction. Therefore under conditions of accelerated oxidation the NAPP value is a reasonable estimate of the possible acid production in all cases except for sphalerite and galena. However, under conditions of less intense oxidation, for instance in columns, waste rock and tailings dumps, the formation of polysulfides is likely to be more widespread thus reducing the correlation between NAPP and the maximum possible acid production.

Jan 1, 2004

By T. Shariff

Titanium alloys have found increasingly wide range of applications in aerospace, chemical, medical, sporting, power generation, oil and gas extraction industries mainly due to the low density, high mechanical property characteristics, biocompatibility, and excellent corrosion resistance. In the manufacturing routes of their finished products, welding has been a key technique used and always been a main concern requiring the stringent compliance to the well defined process. Conventionally, gas tungstenarc (TIG), gas metal-arc (MG), plasma arc, and electron beam welding processes have been used to weld titanium alloys. Nowadays, laser beam welding has provided great challenging applications for titanium alloys due to the low and precise heat input, deep and narrow fusion zone, small heataffected zone, low thermal distortion and high productivity. At the NRC Institute for Aerospace Research, some R&D work has been undertaken for titanium alloys using laser beam welding process. These investigations have mainly concentrated on optimizing the welding process as well as understanding the fundamental process-structure-property relationships. In this invited keynote presentation, the research progresses obtained and the main issues encountered in laser welding of titanium alloys will be briefly summarized.

Jan 1, 2011

By Alan L. Sangster

Abstract -Auriferous, bedding-parallel veins occur in zones of carbonaceous, argillaceous and sulfidic turbidites in the Lower to Middle Cambrian sandy flysch of the Goldenville Formation. The ?34S values for vein and wall-rock arsenopyrite and pyrrhotite, and for regional pyrite and pyrrhotite, are highly positive. The values are similar to those from Cambro-Ordovician sediment-hosted deposits of other types, and display trends that increase upward in the stratigraphic sequence. The similarity in composition of vein and wallrock sulfides indicates a seawater-sulfate source for sulfur, derived from the enclosing rocks at the time of vein formation. The upward increase in ?34S values is consistent with closed system sulfate reduction in the anoxic portion of a stratified water-column. Published ?18C and ?18O values for Meguma Group vein carbonates are unlike those of other gold-vein carbonates, but are similar to those of diagenetic-metamorphic carbonates from the Meguma Group and elsewhere. These data indicate that the source for the vein-related sulfides and carbonates may be the host strata; possibly the arsenic and gold were derived from the same source.

Jan 1, 1992