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By A. Haldar

The major problem encountered in the casting of hypereutectic Al-Si alloys is the stoppage of flow below the rigidity level of solid fraction. In this study, the flow stoppage mechanism was studied using three Al-Si alloys with 14%, 18% and 22% silicon. The horizontal foam patterns used were 12.50 mm (0.50 inch) wide with two section thicknesses 12.50 mm (0.50 inch) and 6.25 mm (0.25 inch) with a common sprue. The primary silicon distribution along the length of the casting was studied to determine the mechanism of flow stoppage. It was found that the surface of the flow tip of Al-14%Si alloy was smooth with a few undulations. As the silicon level increased, undulations at the flow tip increased. The number and size of undulations were maximum for the Al-22%Si alloy. Microstructural analysis using optical image analyzer revealed that the flow tip consisted mainly of eutectic silicon in the aluminum matrix and a few primary silicon crystals (PSC). The PSC were in the interlocked condition few centimeters behind the flow tip. It was also found that the gap between the flow tip and the PSC concentrated area increased with an increase in silicon level. Phase characterization was done with SEM-EDX to identify the precipitating phases.

Jan 1, 2007

By John E. Udd

I N Part I of this paper, Professor Morrison suggested that our technique of causing cracks to develop around openings in a sheet of photoe1ashc plastic is, in effect, a laboratory-scale rockburst. Our investigations have indicated that the location and direction of these cracks are predictable, and that their growth can be controlled. On several occasions, we have been able to cause these cracks to propagate sufficiently slowly to be followed, with the naked eye. In practice, the rate of growth, gradual or sudden, would depend upon rock properties. This part of the paper presents an analysis of the stresses surrounding the openings before and after failure and also this author's views on the causes and after-effects of cracking. An attempt is made to correlate the stress patterns with those deter-mined from pure mathematics. Considering that the openings, except for the central enlargement, are long apertures with somewhat rounded corners, they might be compared with elongated ellipses having axes ratios of about 20:1 or with

Jan 1, 1963

By Timothy W. Ellis, Abbas H. Mirza, R. David Prengaman

Recycled lead, i.e. material produced by the recycling of lead-acid batteries, has become the primary source of lead in much of the world. This has been important to the recycled lead industry as other uses have dwindled, e.g. lead based pigments, chemicals, fuel additives, solders and CRT glasses. Presently, battery manufacturing accounts for greater than 85% of lead consumption worldwide while recycled lead accounts for approximately the same market share of lead supply. Battery manufacturing and production of recycled lead are intimately coupled. In 2007, of all the industrial base metals, lead from lead-acid batteries had the highest recycling rate in North America at greater than 95%. In this paper we will review some of the processes and technologies used in a modern lead acid battery recycling facility, and how recycled lead has become the material of choice for battery construction through the development of a recovery and refining process that exceeds the industry requirements. We will also briefly review an advanced air emissions treatment system in a modern lead recycling plant that demonstrates the feasibility of a new maximum available control technology (MACT) for secondary lead smelters.

Jan 1, 2011

By K. Thuro, H. Käsling, C. Wieser, G. Nuijten

"The time-dependent behavior of brittle rocks during stress relaxation is of great interest for mining industry, nuclear waste disposal as well as tunneling and underground construction. Several studies have shown that both elastic as well as inelastic deformation occur during stress relaxation (Emery, 1964; Zang & Berckhemer, 1989). While elastic strain occurs already during the drilling process, inelastic deformation is time-dependent and can endure for hours, days or weeks. To investigate the evolution of microcracks during core relaxation, two crystalline core samples were recovered from high in situ stress conditions in Europe’s deepest mine in Pyhäsalmi (Finland). Samples were prepared for testing within one hour after coring such that a large portion of the time-dependent component of relaxation could be recorded over several days using ultrasonic velocity as well as acoustic emission (AE) measurements.Results from AE analysis show an exponential decrease in the number of events over a period of several hours. Repeated sudden increases of acoustic events can be related to the propagation or the interaction of cracks. In the first hours of recording also the signal energies reached the highest values and the increases in signal energy correlate well with increased event rates. On additional drill cores, P-wave velocities were measured parallel and in 45° distances perpendicular to the core axis. After core recovery, stress-induced microcracking caused an exponential decrease in wave velocities similar to AE rates. Lowest compressional wave velocities were measured parallel to the core axis and thus normal to the foliation and in the direction of the maximum in situ stress component. The highest measured velocities occurred parallel to the foliation plane. Within the samples, the anisotropy ratios were up to 1.37 at the beginning of the measurements and increased to values of up to 1.8 after 45 days. The wave velocity anisotropy is in agreement with the in situ stress orientations."

Jan 1, 2015

By R. J. Rotzinger

The Gibraltar Mine and Mill facility were commissioned in 1972 by Gibraltar Mines Ltd utilizing a flowsheet consisting of two stages of crushing followed by a rod mill / ball mill grinding circuit. During operations a number of opportunities were evaluated to expand the mill capacity; however, the economics of the day did not allow any of these projects to proceed. The mine continued to operate until late 1998 when it was shutdown and put on care and maintenance due to low commodity prices. Taseko Mines acquired Gibraltar in 1999 and in 2004, with the improvement in the metal markets, made the decision to restart operations. During the restart planning a number of opportunities for mill improvements and upgrades were identified and, after operations were successfully restarted, the decision was made to once again review expansion opportunities for Gibraltar. Taseko evaluated various expansion alternatives eventually deciding to install a SAG Mill, convert the existing rod mills to ball mills and distribute the SAG discharge to the resultant six 6 parallel ball mills. This paper discusses the design, implementation and commissioning of the SAG mill grinding circuit.

Jan 1, 2012

By L Munholand, G. Soucy, P. Quintal

This work presents early results from the first study to optimize the hydrodynamics of a Plasma Lift Reactor (PLR). The PLR is designed to break down organic contaminants in aqueous solutions. New experimental results are presented for air/water tests and for plasma degradation of organic contaminants in Bayer liquor. In addition, a multiphase Computational Fluid Dynamics (CFD) model has been developed which predicts the hydrodynamic behavior in the PLR. These results of this work suggest the PLR is effective at reducing contaminants in the Bayer liquor and that the CFD model adequately describes the hydrodynamic flow.

Jan 1, 2005

By P. Cheung, J. Gulyas, R. Clary

Over the past 50 years, the use of autoclaves in the metallurgical industry has evolved from final metal recovery (hydrogen reduction) and purification (sulphide precipitate oxidation) to treating whole ores and concentrates. Recent process developments, such as the use of autoclaves for laterite leaching, have necessitated higher temperature and pressure operations, which in turn have seen marked advancements in technology and manufacturing capabilities to keep in step with process demands. This paper will discuss the advances in technology in terms of design, materials and construction of autoclaves and liners, typical dip tube design and geometric layout. This paper will also address specific auxiliary equipment, such as acid and steam injection systems, and components, such as agitator seal systems.

Jan 1, 2004

By N. Bahrani

Knowledge of the state of stress in the Earth?s crust is very important to the safe and efficient development of underground excavations in mining and civil engineering projects. A number of methods have been developed over the past 40 years to assess the stress field in the rock mass. These range from local estimates derived from compilation of regional stress databases to back-analysis of field observations to dedicated in situ measurements. The Geomechanics Research Centre (GRC) at MIRARCO has a long history of undertaking in situ stress characterization and measurement. In this paper, the stress measurement techniques used by the GRC, including overcoring and undercoring in addition to borehole breakout back-analysis, are briefly reviewed. The limitations and application of each technique for different ground conditions and the challenges involved during the field work and in interpretation of the results are discussed. A successful stress measurement campaign is not limited to acquiring valid local measurement, but must include a careful interpretation and integration of the measurement with other geological and geotechnical context information. Based on our experience, it is suggested that all available stress indicators and data are combined and integrated with the local geological and geomechanical conditions to derive a consistent stress characterization for a given site.

Aug 1, 2013

By C. A. Pickles, K. Mackowiak, D. Gajonera

"Shake-flask oxidation tests were performed on Red Dog mine waste to study the initial dissolution behaviours of lead, zinc, and iron. The conditions for accelerated acid generation in terms of Eh and pH were determined. Each mineral behaved distinctly, with galena dissolving first, followed by sphalerite, then pyrite, although there was some overlap in behaviour. Iron was not detected in solution until approximately day 40 and was present at low concentrations. The experimental conditions and the theoretical model results indicated the formation of iron oxyhydroxides at low weathering times and jarosite at longer times.RÉSUMÉ Des tests d’oxydation par agitation en flacon ont été effectués sur les déchets miniers de l’exploitation Red Dog afin d’étudier les comportements initiaux de dissolution du plomb, du zinc et du fer. Les conditions entraînant la production accélérée d’acide en termes d’eH (potentiel d’oxydoréduction) et de pH (potentiel d’hydrogène) ont été déterminées. Chaque minerai se comportait différemment ; la galène a été la première à se dissoudre, suivie de la sphalérite, puis de la pyrite, mais un certain chevauchement des comportements a été observé. La présence de fer en solution n’a été détectée qu’après environ 40 jours et ce, à de faibles concentrations. Les conditions expérimentales et les résultats du modèle théorique signalaient la formation d’oxyde-hydroxyde de fer sur de courtes périodes d’altération atmosphérique, et de jarosite sur des périodes plus longues."

Jan 1, 2017

By W. van der Merwe

ABSTRACT With the gold industry processing more complex ores, the online measurement and control of cyanide addition to the gold leaching circuit has become more critical. This paper compares the two commonly employed ‘free’ cyanide online analysis methods (amperometric and potentiometric endpoint silver nitrate titration) with the rhodanine endpoint silver nitrate titration and ion selective electrode methods common at site laboratories. Measurement differences between these methods are presented and discussed for cyanide solutions containing copper and zinc with varying cyanide to metal ion ratios. The resulting cyanide available to leach gold is also compared using these measurement techniques.

Jan 1, 2013

By Francois Charette

Corrosion is a significant factor affecting the capacity and working life of ground support. The paper explores a relatively simple method to predict the load capacity of a support system using a Monte Carlo stochastic approach. The analysis uses published field data on existing ground support to evaluate the applicability of the method and its predictive performance. Discussion on corrosion rates found in the field and predicted from laboratory measurement is provided.

Jun 1, 2012

By V. Panayotov, M. Panayotova, R. Villas-Bôas

The "United Nations Framework Classification (UNFC-2009) for Fossil Energy and Mineral Resources 2009” is the international system designed to meet (to the extent possible) the needs and to support the decision making and resources management of private industry investment, governments, policymakers, bank investment, scientists. There are different international and national systems classifying commodities (resources, reserves, possibility and feasibility to extract them, etc.) with their own definitions and reporting terminology which often do not overlap entirely or even differ significantly - thus creating difficulties and problems among stakeholders to understand each other. The UNFC-2009 is developed to allow “speaking in one language”. The paper presents briefly the UNFC-2009. The UNFC-2009 applies simultaneously three fundamental criteria to classify projects: economic and social viability, field project status and feasibility, and geological knowledge (so called E, F and G axes), thus creating a visualized, easily understandable three dimensional system. The E, F and G axis categories are divided to subcategories, using additional criteria. The UNFC-2009 is already applicable to solid minerals, nuclear fuel resources, petroleum. The amounts of solid waste generated by metals production from ores (mining, minerals beneficiation, extraction metallurgy) and its metals content are discussed from the viewpoint of using the waste as resource. An attempt is made to apply the UNFC-2009 to technogenic waste from metals production from ores - both to old engineering constructions (historic mining dumps and reclaimed beneficiation tailings ponds) and new (currently in use) dumps and ponds.

Jan 1, 2016

By E. L. Martheleur

The use of electricity in coal mines dates almost from the time when it was realized chat it could be used to produce mechanical power. The first motor put in service underground was installed to drive a small pump nearly 40 years ago, and since then the use of electricity in mines has reached an extent undreamed of at that time. We now find its universal adoption in all the mining countries of the world. Great progress has been made in the development of mining electrical apparatus in the last decade, and excellent and adequate material is now available for the use of electricity underground. Although mining accidents, due to the use of electricity, are not frequent, the miner is justified in demanding chat all electrical apparatus for installation below ground be constructed with a greater degree of safety than that used on the surface. That this view is shared by the authorities of the different mining countries is evidenced by governmental regulations relative to the use, erection, and maintenance of electrical apparatus below ground. Those with which we are specially concerned are the regulations for the installation and use of electricity in the coal mines of Nova Scotia. The potential dangers of electricity in coal mines are: Shock or burns by contact from live parts. Shock or burns by contact with parts which, although normally dead, have become accidentally alive. Fire. Explosion of gas or coal-dust Explosion of apparatus.

Jan 1, 1928

By A. Roy MacLean

"Cape Breton is an island on the eastern extremity of Nova Scotia, Canada. Here, coal mining under the Atlantic Ocean has been a way of life since the early French militia mined coal for heating purposes in 1720. Despite many ups and downs over the intervening years, the coal industry has survived and is now in a favourable position to benefit from the upswing in international coal usage.Mining in Cape Breton Early mining in Cape Breton was done by hand picks and shovels. The coal was loaded into mine cars which were hauled by horses to the main haulage system for transport to surface. Later, compressed-air cutting machines and drills led to the use of explosives to blast the coal so that it could be loaded by hand and transported as above. In 1923, longwall mining (by hand) was introduced. In 1950, the Dominion Coal Company developed the Dosco continuous miner in order to mechanize the longwall coal-getting operation. At this time, conveyor belts came into wide-spread use, along with diesel locomotives to haul mine cars from the longwall face to the main transport system. During this period, coal was also mined by conventional mechanized room-and-pillar equipment such as cutting machines, loaders, roof bolters, etc. This system evolved into the use of the continuous ·miners of today, which are employed in the Lingan Mine room-and-pillar section. However, this method is only satisfactory at shallow depths and gradients. For these reasons, almost all the coal in this coal field will be mined by longwall methods. In 1968, the Government of Canada expropriated the assets of the Dominion Coal Company on Cape Breton Island in order to prevent complete closure of an uneconomic industry by its owners. The government created, by an Act of Parliament, the Cape Breton Development Corporation which now operates the coal mines, coal preparation plants, railway, shipping pier and ancillary services (Fig. 2). Since its inception, the Corporation has closed three mines, opened two new mines, is in the process of developing a third new mine, and has invested heavily in the one mine which remains from its previous owners."

Jan 1, 1985

By B. Schulz, T. Leißner, R. G. Merker

"Ores enriched in critical rare earth elements (CREE) keep on being of particular interest. The CREE are Nd, Eu, Tb, Dy, including Y. In conjunction with beneficiation tests on Y-mineral bearing flotation tailings of complicated mineralogy, the Mineral Liberation Analyses (MLA) was used to work out processing characteristics fraction-wise in terms of modal mineralogy, mineral recovery, locking and liberation, and particle size.Size fractions from mechanical sieving (“real fractions”) as well as fractions created virtually by using filters on the MLA-data of the unsieved head material (“virtual fractions”) were investigated comparatively thereby. The ""virtual-sizing-approach"" features a much simpler sample preparation procedure and considerably lower cost if a fraction-wise investigation of a head sample is needed. It can be conveniently applied to intimately locked ores needing a fine grinding to a particle size distribution (PSD) range below 25 microns for instance. However, its practical use is sometimes disputed in terms of the reliability of the results. Results are shown for the main Y-bearing mineral xenotime and selected main gangue minerals of a low grade REE-ore.The influence of sample representativeness, sample preparation and particle counting statistics turned out to be of crucial importance. Given that all preconditions for reliable results are met, locking characteristics, modal mineralogy, and even PSD trends can be read from virtual fractions.The authors encourage processing engineers to use the virtual approach. They propose practical measures to improve the reliability of the MLA results, identify and tackle conflicting results, and mitigate evaluation problems that may arise."

Jan 1, 2016

By G. Scamans, J. Lazaro-Nebreda, Z. Fan, J. B. Patel

"Melt quality is crucial for both continuous and shape casting of light alloys and in order to improve it, removal of excessive inclusions, accumulated impurities and unwanted gases becomes necessary. To address this problem, a new multi-purpose high shear liquid metal treatment technology, based on intensive melt shearing by a rotor/stator unit, has been developed. The device ensures achieving uniform temperature and chemical composition and an efficient dispersion of gas and solid phases in the melt with minimal disturbance of melt surface, and can be used, among other things, for de-gassing and de-ironing of Al-alloy melts. Efficient degassing is achieved by dispersing each argon bubble into many small ones, which significantly increases the overall surface area of the bubbles and the time they remain in the melt capturing hydrogen before reaching the surface. This allows using much lower inert gas flow and mixing times than conventional rotary degassing. When applied to Al-alloy scrap, with accumulated iron, the high shear melt treatment speeds up the nucleation and growth of primary Fe-rich intermetallic particles, allowing a faster removal rate. Therefore it reduces processing times, increasing recycling productivity, and facilitates full metal circulation of secondary Al-alloys.INTRODUCTION Aluminium and magnesium alloys are widely considered in various industrial sectors for the purpose of weight saving (Polmear, 1995). In particular, they are used in the automotive sector, where components are mostly manufactured by high pressure die casting (HPDC) because of its simplicity and relatively low cost, but efficiency and mechanical properties are quite low compared with other processes. To date, the main focus to overcome this problem has been for improving the HPDC machinery (Dahle, 2001) but little attention has been paid to the opportunities of controlling the nature and quality of the molten metal supplied to the die. In this way, liquid metal treatment, which involves a variety of physical and/or chemical processing methods to improve melt quality prior casting, is crucial for both continuous and shape casting products."

Jan 1, 2018

By E. C. Roper

THE Britannia Mining & Smelting Company, Limited, have been operating their property at Britannia Beach, B.C., continuously for nearly forty years and have mined over 33,000,000 tons of ore from orebodies within a belt of highly sheared rocks, five miles long by 2,000 feet wide. The property is in the Coast Range mountains, about twenty miles due north of Vancouver. The mountains rise abruptly from sea level to elevations of 4, 500 feet within a horizontal distance of 7,000 feet. The topography has enabled the orebodies to be developed by adit tunnels. The active mining levels are connected to the adits by incline and vertical service shafts. The main service adits are the 2200, 2700, and 4100 levels (see Figure 1). The mine surface shops, three bunk-houses, and over one hundred dwellings form the townsite camp at the portal of the 2200 level adit. A small camp of one bunk-house and a few dwellings is situated at the 2700 level portal. The beach surface shops and camp, adjacent to the 4100 level adit, service the mill, foundry, and other beach installations as well as the mining from the 4100 level. The ore mined from the various orebodies is delivered to the 4100 main haulage level through a system of rock raises and intermediate tramming levels and is hauled on the 4100 level to the mill.

Jan 1, 1945

By E. Ghali, B. Arsenault

Aluminum alloys play an important role in the manufacturing of air and ground vehicles. However, with such alloys, corrosion damage is often found on structural components subjected to fatigue loading. The alloying provides large benefit in terms of the high specific tensile strength (ultimate strength/density ratio) to the aluminum alloy but causes the aluminum alloy to be more sensitive to localized corrosion due to complex microscopic heterogeneities such as secondary phases. This paper investigates thermal spray coating namely arc spraying to evaluate the protection against environmentally assisted cracking (EAC) and localized corrosion on Aircraft structural 7075 T651 aluminum alloys. In particular, EAC and pitting corrosion at the interface coating-substrate are a challenge for thermal spray protective coatings on aluminum alloys under cyclic load and immersion. To address these issues, different surface preparation techniques prior to arc spraying were considered such as chemical de-oxidation, laser ablation, shot peening and grit blasting. Results indicate that surface preparation and improved coating process parameters play an important role to provide a coating conferring a protection against both localized corrosion and EAC.

Jan 1, 2006

By R. R. Culbert

Several thousand parts per billion of uranium are present in some alkaline lake and ground waters of the Okanagan region, British Columbia. To a major extent the uranium content of these highly anomalous waters is controlled by their levels of dissolved bicarbonate. In lakes, dissolved bicarbonate and the organic content of the sediment largely control the partitioning of uranium between sediment and water. This relationship is found to a lesser extent in alkaline creeks, and transported geochemical anomalies in soils appear where uranium-bearing alkaline ground waters have encountered organic materials. There is a possibility that young, near-surface deposits (with very low radioactivity) are forming from these uraniferous waters.

Jan 1, 1978

By George P. Demopoulos, Nima Parsi Benehkohal, Marianna Uceda

Lithium-ion batteries (LIBs) find wide range of applications from portable electronics to electric cars and stationary storage or renewable energy. LIB electrode fabrication is done through mixing the active material (Li-ion host) with carbon (conductive component) and polyvinylidene fluoride (PVDF), which acts as a binder. These components are dissolved in N-methyl-2-pyrrolidone (NMP) to form a paste which is then doctor bladed onto the aluminum current collector. NMP is a toxic chemical and the overall fabrication process remains costly. Efforts are made of eliminating NMP by (1) replacing the binder and (2) using a new fabrication method. Of particular interest among these new methods is electrophoretic deposition (EPD). Via the application of DC potential, particles in suspension can be electrophoretically deposited on different conductive substrates in a relatively fast rate rendering EPD feasible for industrial application. A key aspect for successful application of EPD is the formulation of a stable suspension. Within the McGill HydroMET group, we explore the potential of EPD in fabricating LIB electrodes having demonstrated its effectiveness in the case of P25 nanotitania/carbon anodes. The performance of EPD fabricated TiO2/C electrodes is compared to standard PVDF-based electrodes and shown to have comparable charge capacity. This method is now being extended to other electrode materials. In this paper an introduction to the EPD method will be made and subsequently its use in fabricating LIB electrodes will be described. The performance of the fabricated batteries is evaluated via galvanostatic charging/discharging and cycling tests.

Jan 1, 2016