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By Maurice Lauzon

"Aerial surveys of the open pits have been conducted regularly at Lake Asbestos of Quebec, Ltd. -a subsidiary of American Smelting and Re-fining Company -since 1958. Ground controls are supplied by Lake Asbestos, and a topographic map of the pits at a scale of 1 in. to 50 ft., with 2-foot contour intervals, is obtained by aerial photography. The information from the topographic map is then transferred by the Lake Asbestos engineering staff to sections from which the volumes removed are calculated. Considering the size and complexity of the operation, this system has proved to be the cheapest, fastest and most accurate way of determining the quantities of rock and overburden removed. More than 11,000,000 tons of ore and waste are mined each year in three different pits. Further-more, the nature, shape and extent of the orebodies make it necessary to mine on many (up to eight) benches of a pit during a single year. In addition, there are sections of the pits where it is impossible or un-safe to survey the crest of some benches by standard ground methods. For these reasons, the tonnages obtained by truck count are checked and adjusted by aerial survey. These surveys are now taking place every six months. With this system, it is possible for a two-man surveying crew to look after all field work in the mine area."

Jan 1, 1967

By Silvana Costa

The quality of life in remote mining communities is a significant factor that impacts the mining industry?s ability to attract and retain high quality workers in remote areas. The rapid growth of mining development, along with the shortage of skills and training globally are reflected in an increasing need to identify the ideal conditions for employee wellbeing and investigate ways to improve quality of life of miners and their families in remote locations.

May 1, 2007

By J. Baz-Dresch

"The most cost-effective method of placement of the high strength fill used in the Cannon Mine' s overhand cut-and-f ill bench stopes was determined to be truck haulage. Constraint s imposed by the mine layout dictated the use of a truck which could dump its load in a fifteen-foot high drift. The Dux Teledumper truck was selected as the most suitable unit for this application based upon operational and maintenance parameters which included a telescoping, tilting dump box; large load capacity; and robust construction. Development of the truck continues through the cooperation between the manufacturer and user. INTRODUCTIONThe Cannon Mine is situated in the centre of Washington state, approximately midway between the cities of Spokane on the east and Seattle on the west. The mine complex is located three block s south of the Wenatchee city limits at the eastern base of the Cascade Mountain range.Asam era Minerals (U.S.) Inc., with 5I% ownership, operates the Cannon Mine. Breakwater Resources, Ltd. holds the remaining 49%.Annual paroduction is 520 000 tons per year, presently on a 21-shift per week operating schedule for both the mine and the mill.All production is presently won by overhand bench stoping with backfill. Stoping starts with 15-ft high by 24- or 30-ft wide sill cuts driven above and below a stope block . A drop rai se and slot are used to open a bench which is then slabbed toward the open slot. Truck-placed backfill is dumped into the mined - out stope from the upper sill cut. This stoping sequence is repeated until the top of the ore block is reached . The top sill cut is then tightly filled with backfill to minimize subsidence and to provide adequate roof support during extraction of the pillars.Mining equipment consists of hydraulic drills and rubber-tired, diesel scoops and trucks."

Jan 1, 1989

By N. Maleki

In recent years, research and development of magnesium alloys have been greatly promoted by the lightweight requirements in critical industries. The use of these alloys, however, has been restricted by their limited mechanical properties especially at high temperatures. The disadvantages can be overcome by producing Mg matrix composites. The Mg?Si alloys containing in situ Mg2Si particles have found a great potential as structural materials. Unfortunately, Mg2Si compounds are prone to form undesirable coarse Chinese script morphologies, which would deteriorate the properties of the materials. Refinement of microstructure is performed for improvement of wear and corrosion resistance. This paper investigates the microstructure and corrosion behavior of pure magnesium, unmodified and modified magnesium matrix composites reinforced with Mg2Si particles. The Mg2Si/Mg composite was prepared via a normal cast route, and then various amount of zinc was added to melt in order to modify the Mg2Si reinforcement particle morphologies. The microstrucrures were characterized by optical and scanning electron microscopy followed by EDX analysis. The corrosion behavior of Mg/Mg2Si composite was investigated by using potentiodynamic polarization measurements. The results showed that by addition of zinc, the average size of the primary Mg2Si became significantly decreased from about 100µm to about 20µm, as well as its morphology changed from dendritic to a polyhedral shape. However, by adding extra amount of zinc many primary Mg2Si particles become coarse again. It was also found proper amount Zn addition increased the corrosion resistance of Mg/Mg2Si composite.

Oct 1, 2011

By H. L. Gibson, T. N. Setterfield, J. J. Watkins, R. W. Hodder

"Abstract - The McDougall-Despina fault set in the Noranda district of northwestern Quebec defines the eastern margin of the Despina cauldron, nested within the district-scale Noranda cauldron. The faults are stratabound in that they displace stratigraphy of the cauldron fill, but do not off-set the cauldron cover. The faults are occupied by dikes that acted as eruptive centers to volcanic members of the cauldron-filling sequence. Measurable displacement across the McDougall-Despina fault set is greater than 750 m, and coincident with post-cauldron volcanism. Feeder dikes cross-cut each other and are typically depleted in Na2O and CaO, and enriched in MgO, K2O, Fe2O3 and MnO relative to fresh flows. Economic and subeconomic massive sulfide deposits occur adjacent to the McDougall-Despina fault set at different levels over a stratigraphic thickness of 3000 m. These include the Corbet deposit, the subeconomic D-68 Zone deposits, and the subeconomic stringer zones of South Rusty Hill and Bedford Hill. Numerous copper occurrences and abundant hydrothermal alteration occur in and immediately adjacent to the fault set.The McDougall, Despina, and adjacent, parallel, ancillary faults define a synvolcanic fault set which controlled the location of magmatism, hydrothermal alteration and mineral deposition during the early evolution of the Noranda cauldron. Significant sulfide mineral deposition commonly occurred in proximity to the intersection of the McDougall-Despina fault set with northeast-trending synvolcanic faults. Recognition of synvolcanic faults is therefore a major objective of exploration programs for volcanic-associated massive sulfide deposits."

Jan 1, 1995

By Alfred C. Lane

Reference to the original use of the terms Laurentian and Huronian (and its extension), shows that the former was applied to granitized sedimentary and metamorphic pre-Cambrian rocks, and the gneissoid igneous rocks associated therewith, and the latter to non-fossiliferous rocks supposed to be later. But it appears from the work of Collins, Quirke and others that there is more or less of an overlap, and that of the original Laurentian the Grenville limestone, and some of the granites, may be later than the lowest part of the original Huronian. Before we can decide whether to abandon one or the other of the two terms, or how to delimit them, it is important to know the extent of this overlap. The Pb :U ratio, though not to be depended upon too minutely, does give a real idea of the age of a mineral as it increases with the decay of uranium, and so is greater the longer the time since the uranium was separated: and there are reasonable prospects of help there from in getting a knowledge of the relative age of different granites to assist in solving the problem, as facts already collected show. 1. Historical review of the use of the words Laurentian and Huronian: 2. Difficulty encountered: 3. Popular account of atomic disintegration: 4. Methods of estimating age by it: 5. Applications.

Jan 1, 1925

By H. L. Gibson, T. N. Setterfield, J. J. Watkins, R. W. Hodder

"The McDougall-Despina fault set in the Noranda district of northwestern Quebec defines the eastern margin of the Despina cauldron, nested within the district-scale Noranda cauldron. The faults are stratabound in that they displace stratigraphy of the cauldron fill, but do not off-set the cauldron cover. The faults are occupied by dikes that acted as eruptive centers to volcanic members of the cauldron-filling sequence. Measurable displacement across the McDougall-Despina fault set is greater than 750 m, and coincident with post-cauldron volcanism. Feeder dikes cross-cut each other and are typically depleted in Na2O and CaO, and enriched in MgO, K2O, Fe2O3and MnO relative to fresh flows. Economic and subeconomic massive sulfide deposits occur adjacent to the McDougall-Despina fault set at different levels over a stratigraphic thickness of 3000 m. These include the Corbet deposit, the subeconomic D-68 Zone deposits, and the subeconomic stringer zones of South Rusty Hill and Bedford Hill. Numerous copper occurrences and abundant hydrothermal alteration occur in and immediately adjacent to the fault set.The McDougall, Despina, and adjacent, parallel, ancillary faults define a synvolcanic fault set which controlled the location of magmatism, hydrothermal alteration and mineral deposition during the early evolution of the Noranda cauldron. Significant sulfide mineral deposition commonly occurred in proximity to the intersection of the McDougall-Despina fault set with northeast-trending synvolcanic faults. Recognition of synvolcanic faults is therefore a major objective of exploration programs for volcanic-associated massive sulfide deposits."

Jan 1, 1995

By Gonzalo Mato, Colin Godwin, G. Ditson

"The mid-Cretaceous Seagull batholith intruded Mississippian sedimentary and volcanic rocks and Jurassic(?) granitic and ultramafic rocks within the Omineca Crystalline Belt in the Yuk on Territory near the British Columbia boundary. Leucoerotic fluorine- and boron-rich granites of the batholith exhibit many textural variations from aplite to pegmatite, but are dominated by a coarse-grained seriate unit and a fine-grained porphyritic unit.Four distinctive tin vein occurrences within and near the batholith are described, the most interesting of which is the MC showing of quartz-calcite-chlorite-cassiterite veins in intensely fractured zones of sedimentary and volcanic rocks. Three other showings occur within the batholith:J) the EC showing of quartz-fluorite-cassiterite-sulphide veins with prominent muscovite-illite alteration;2) the DU showing of quartz-hematite-fluorite-sulphide- sulphide-cassiterite with considerable manganese staining and sericitic alteration; and3) the VAL showing of quartz-tourmaline-cassiterite-fluorite-arsenopyrite veins with little associated alteration.Most cassiterite occurrences are within easterly-trending, vertical structures and all occurrences are thought to represent parts of a single system. These mineralogical and physical variations are apparently related to the distance from the upper contact of the batholith.For the Seagull batholith, Rb-Sr isotopic data give a 100±1.4 Ma isochron age that is concordant with the K-Ar model age from biotite of 101±4 Ma. Initial Sr isotopic ratios for the batholith are high at 0.712, indicating an old, sialic crustal source for this pluton. This initial ratio is similar to values for granitic rocks associated with tungsten deposits in the Yukon Territory. The high initial ratio for Sr, the high Si02 content, the high s/I index, the presence of normative corundum. leucogranitic composition and associated lithophile-tungsten mineralization demonstrate that the Seagull batholith is probably an S-type granitic body. This factor is significant to regional exploration jar tin and tungsten in the Canadian Cordillera."

Jan 1, 1983

By I. Thobadi, C. Pawlik, K. Bisaka, S. Mokoena, M. Erwee

The PyEarth™ process developed at Mintek has been demonstrated successfully at pilot scale. Nine tons of ore containing 2.3 mass % of total rare earth oxides (TREO) from a dormant mineralogically complex iron-rich ore deposit, was subjected to a concentrating smelting step in a 200 kW DC open-arc pilot furnace and the rare earths from the resulting slag were extracted via a hydrometallurgical route. This ore deposit is practically not amenable to extraction by conventional methods. The testwork results proved that the PyEarth™ process was able to optimize the extraction of rare earths while minimizing waste through the removal of iron as a saleable iron alloy. Reduction of iron to the alloy in the smelting step was found flexible, efficient, and controllable, while rare earths were left virtually unreduced in the slag phase. The slag chemistry is selected to optimize both the smelting and leaching performances as well as the alloy composition. Leaching of the resulting slag was found possible and most efficient in hydrochloric acid amongst other lixiviants tested.

Jan 1, 2017

By N. A. Duke, R. L. Carpenter

Abstract - The West Meliadine area is underlain by structurally interleaved panels of mafic and minor ultramafic metavolcanic rocks and metasedimentary rocks that occur along the northern margin of the Neoarchean Rankin Inlet greenstone belt. Three structural and metamorphic domains are recognized: (1) the easterly Wesmeg domain; (2) the central Barracuda-Ridge domain; and (3) the westerly Peter Lake domain. The Wesmeg domain is characterized by a series of southeast-trending, north-dipping, foliation-parallel panels of greenschist facies mafic metavolcanic and metasedimentary rocks. The Barracuda-Ridge domain is comprised of greenschist to amphibolite facies mafic metavolcanic rocks that define an east-northeast-trending structural grain. The Peter Lake domain consists of amphibolite facies mafic metavolcanic rocks and minor metasedimentary rocks intruded by a monzonite pluton. West Meliadine hosts the economically significant Wesmeg gold deposits, as well as other important gold showings across the Barracuda-Ridge and Peter Lake domains. The geological setting of the Wesmeg gold deposits resembles that of a break or fault zone. The Pyke Break is a major geophysical discontinuity (>65-km strike length) and is the first-order structural control on gold mineralization at West Meliadine. It is several kilometers wide and characterized by polyphase deformation and shear zone development accompanied by lode-gold mineralization. In general, gold concentration is related to quartz and iron-carbonate veining, iron sulfides (mainly arsenopyrite and pyrrhotite), and accompanying silicate alteration minerals that overprint favorable chemical and structural traps late in the history of deformation.

Jan 1, 2004

By J. D. Campbell

"Coal is one of Alberta's major fuel resources, but its distribution, especially in the flat plains region, has been somewhat obscured by surficial deposits. After a period of neglect, easily strippable plains coal is presently approaching a position of dominance in electrical power production, a position it is likely to retain for a number of decades in the face of strong competition from hydro and nuclear power. Accordingly, the Research Council of Alberta has undertaken an inventory survey of the province's supplies of this resource.In the southern part of the province and in the north-central forest-fringe area, some strippable coal is found in the Belly River Formation and its equivalents, but major strippable coal reserves in large areas of central Alberta occur within the Edmonton Formation. The survey is planned on a reconnaissance scale, drilling test holes at 2-mile intervals in selected large areas. It appears to show that, in well-settled regions, large reserves of strippable coal are only to be expected where they have long been known; major presently unknown bodies of coal must be sought in unsettled regions or at depths too great for strip mining. However, such bodies might still be economically competitive with hydro and nuclear power in the production of electric power for some time to come."

Jan 1, 1967

By C. Tissot, R. Palmer

"Due to the low concentrations of gold, direct measurement of gold concentration in ore on belt has not been seriously considered to now. Pre-concentration or sorting strategies have largely consisted of particle sorting based on secondary characteristics such as colour, which can be successful in select cases. CSIRO has produced sample measurement results using gamma activation analysis of ~300 gm samples with accuracies of around 30 ppb at best. With this encouragement, a feasibility study into gold ore measurement on belt for the purpose of sorting pods of gold ore has been undertaken. The study described here included, prototype design options with existing industrial Linacs, extensive Monte Carlo modelling of measurement sensitivity and shielding, further sample measurement, a study of the interaction of target measurement accuracy and sorting efficiency, and a rough estimation of potential economic benefit. The projected model sensitivity of around 0.1-0.15 ppm (1 standard deviation) in 10 seconds for 1 ppm average feed result in good bulk sorting performance and intriguing economic potential.INTRODUCTION Pre-concentration or sorting strategies for gold ores have largely consisted of particle sorting based on secondary characteristics such as colour or density, which can be successful in select cases (Klein, 2010). No method is available to measure gold content for sorting in particles or even in bulk on belt, principally due to the low concentrations of gold present. In fact, in many cases it is difficult to do rapid bulk grade measurements of base metal ores with concentrations many orders of magnitude higher. By a fortunate quirk of nature gold is particularly amenable to gamma activation analysis (GAA). CSIRO has performed extensive work in GAA of samples of crushed ore (Tickner, 2017). This has resulted in the Photon AssayTM technique that is currently being commercialised through the CSIRO spinoff company Chrysos. The technique relies on the recent availability of industrial high intensity X-ray sources such as Linacs which are currently being used in industry for security, medical and sterilisation applications. This development has led to CRC ORE funding a feasibility study to determine whether on-belt measurement of gold concentration is possible at a rate and accuracy sufficient to be useful for bulk sorting, where pods of ore are diverted rather than individual rocks. The study in the first instance is based on Monte Carlo modelling that has successfully predicted the performance of the sample based gold measurements. As well as the measurement feasibility consideration was also given to the likely heterogeneity of gold ores and hence the degree to which useful separation could be achieved. This is then tied to a back of the envelope evaluation of the order of magnitude economics of bulk sorting in an example deposit."

Jan 1, 2017

By Chenming Liu, Xiao Lin, Bo Wang, Hongbin Cao, Xingang Li

Over 2 million tons of NH3-N were discharged in China per year recently, rare earth industry contributed 7.03% of NH3-N pollutant from industrial wastewater in 2007. Wastewater containing NH3-N and heavy metals mainly produced in RE extraction saponificated with ammonia and precipitated by ammonia bicarbonate. Generally, 1 ton REO cost 0.6-1.2 ton ammonia for extraction and 1.6 ton ammonia bicarbonate for precipitation, and produce 35-100 ton wastewater. Processes, like Na-saponificated, Ca-saponificated and Non-saponificated technique, are widely studied to reduce the adverse environmental effect of RE industry, while traditional processes still have advantage in production cost, process stability and product quality. In this study, a novel process that combines distillation and air-stripping is developed. NH3-N is removed and recovered based on relative volatility difference of NH3 and H2O. Phase equilibrium, heat equilibrium are calculated to determine process parameters. Hydrodynamic performance like flow field distribution is also simulated. Then, design parameters for distillation trays or structured packing are determined based on calculations and simulations. Besides, the phase diagram of (NH4)2SO4-NH4Cl-H2O in 30°C - 100°C, the typical salts composition of nonferrous wastewater, is studied to ensure commercial plants’ continuous operation. Ammonia removal tower (ART) with different high efficient column internals is designed to fit RE wastewater treatment requirement. The novel process has been commercialized in RE industry in Jiangxi, China. The commercial project operation results show the novel process reached a nearly zero-emission with >99.5% NH3-N was removed and then recovered as ammonia. Combined the novel process, the traditional REO separation process using ammonia and ammonia bicarbonate could achieve NH3-N reuse and the effluent quality meets the discharge standards.

Jan 1, 2016

By Vincent Doyon

For several years, the GDD SSW EM Probe is being used in nickel?s mines in Canada and Brazil to define ore limits, reduce dilution and predict nickel grades. It is used with success to test most if not all percussion blast holes at all Falconbridge Mines in Sudbury and Raglan and all Inco?s Thompson mines. However, after testing the SSW Probe in other metal mines, we realized that EM conductivity does not define ore limits by testing blast holes for copper, zinc or gold. For non-conductive ores, no instrumentation is yet available on the market to reduce dilution, by outlining quickly and inexpensively the real shape of an orebody. To that effect, Instrumentation GDD Inc has developed a new revolutionary photonic probe that will make the reduction of dilution possible by probing blast holes. Once surveyed with the probe, a computer draws graphs of the ore grade as a function of depth for each blast hole. A contribution by Canada Economic Development made possible the development of this new technology. Canmet and Soredem also cautioned this technology developed by Instrumentation GDD Inc. This new photonic probe will allow: 1) to better understand the shape of the orebody 2) to raise the grade of the ore fed to the mill 3) a more complete extraction of the ore 4) to raise the competitiveness of mines

Oct 1, 2004

By B. D. H. Knights, N. B. du Preez

The recovery of the economy of the Democratic Republic of Congo has allowed for the rapid increase in production of copper from this region, while the increased price of cobalt continues to support the recovery of that country’s economy. This has enabled the modernization of the process technology used, particularly the change from direct electrowinning of copper to solvent extraction-electrowinning. With this change has come a variety of technical challenges in optimizing the recovery of cobalt from these sources. In this paper, we discuss aspects of the flowsheets for the production of cobalt from the ores of the DRC and Zambia, highlighting the technological improvements that have been made. Following this description of the practice, we assess the challenges of further improving the recovery and purity of cobalt from these sources. INTRODUCTION The African Copperbelt (Figure 1) is by far the biggest producer and holds the greatest reserves of cobalt (Sheed, 2015). However, the ores of this great mining region are extracted primarily for their copper content, and cobalt is a by-product. The ratio of copper-to-cobalt is between 6 and 20 to 1, with the ores from the DRC richer in cobalt than those from Zambia. The overall supply of cobalt, shown in Figure 2, is increasing due to an increase in demand for its use as a battery material. Cobalt is used in superalloys, hard metals, pigments, catalysts magnets, tyre adhesives, lithium-ion rechargeable batteries, and wear-resistant coatings, amongst others. Although these generic categories persist, Figure 3 shows how the relative usage of cobalt is changing due to the uptake of electric vehicles in China and Europe. Cobalt is a key element in lithium-ion batteries, and because it is widely anticipated that electric vehicles will be legislatively encouraged, it is anticipated that the demand for cobalt will rise. This anticipated increase in demand resulted in an increase in the price for cobalt, to which suppliers responded over-eagerly, and the price has dropped dramatically in the first few months of 2019, as shown in Figure 4. However, there is a clear cycle of price peaks in cobalt’s history.

Jan 1, 2019

By J. W. Senn

A magnesium alloy modeled after commercial alloy WE54 was thermomechanically processed and characterized to understand the mechanisms by which its texture can be randomized, as reported by Ball and Prangnell [1]. Samples were deformed in plane strain compression to prescribed strain levels at temperatures high enough to prevent cracking and then recrystallized. The deformation texture is very similar to that observed after plane strain compression (e.g., rolling) of other Mg alloys, such as common AZ31. However, the texture can radically evolve during recrystallization. Annealing above the precipitate solvus temperature results in a nearly random recrystallization texture where the initially strong basal texture is completely eliminated. Annealing below the solvus temperature produces a recrystallized texture similar to conventional Mg alloys, i.e., a weakened basal texture. If this same material is then annealed above the solvus to promote grain growth, a randomized texture evolves, which is similar that of samples simply recrystallized above the solvus. It is hypothesized that a sort of preferred growth mechanism, whereby grains with random orientation grow faster than those with the original basal texture, contributes significantly to the texture randomization observed in wrought magnesium alloys containing rare earth elements.

Jan 1, 2006

By T. Billotte, G. Tirand, J. Zollinger, V. Robin, B. Rouat, D. Daloz

The grain structure prediction of metallic alloys during a welding process is often an issue. In addition to the welding parameters and the alloy nominal composition and properties, the base metal grain structure and chemical homogeneity also play an important role in the formation of the final microstructure. In this paper intensive characterisation of solidification structure in gas tungsten arc welding of Ni base alloy 600 are described. It is shown that in transverse section of the weld, while the grain structure shows some texture following constrained solidification growth, grain density in the weld is similar or greater than grain density in the heat affected zone. This suggests that simulation of the welding structure needs, in order to be predictive, to take into account : epitaxial growth, secondary nucleation events and 3D growth inside the weld pool.

Jan 1, 2015

By Akiyoshi Horiuchi, Manabu Kanno, Shigeki Sato, Taro Aichi

"AKITA ZINC Co., Ltd. (Iijima Zinc Refinery), jointly owned by DOWA METALS & MINING Co., Ltd.(DMM), has used the company’s own hematite process for iron control since the beginning of operations in 1971. The hematite process consists of reductive leaching with SO2 gas and iron removal in autoclaves by high temperature hydrolysis. This process enhances not only zinc recovery but also the recovery of gold, silver, copper, lead and rare metals, which is carried out at another DOWA metallurgical plant. All by-products produced in the hematite process are marketed and sold. This paper presents an overview of the hematite process and the recent process improvements made.INTRODUCTION DMM carries out mining and smelting activities for precious metals, PGMs, rare metals and base metals such as copper, lead and zinc. It owns KOSAKA SMELTING & REFINING, producing copper and lead, and the AKITA ZINC Co., Ltd. (AZC) in Akita Prefecture. DOWA is a specialized smelting company which has established a metallurgical complex for copper, lead and zinc, including a recycling business. AZC was established in 1971 at a production capacity of 72,000 t/y zinc; it is jointly owned by DMM and five other non-ferrous metal companies. AZC has increased its capacity continuously and now produces 210,000 t/y of zinc. Figure 1 shows the changes in zinc production and capacity at AZC."

Jan 1, 2016

By Frank Mucciardi, Louca Gourtsoyannis

"Low and inconsistent recoveries of aluminum in the production of aluminum-killed steels triggered an extensive research program on the aluminum dissolution kinetics at McGill University. This research program led to the understanding of the melting kinetics and the hydrodynamics of making additions to liquid steel. It showed the necessity of gradually releasing liquid aluminum at the bottom of the ladle to increase aluminum recoveries.This knowledge was verified in practice at Sidbec-Dosco, where a prototype aluminum wire injector was developed and installed for the first time in Canada. The industrial application showed the validity of the theoretical and experimental results and provided further data for the mathematical modelling of the process.The development of the theoretical understanding, the industrial results, and the interaction between university and industry are presented.IntroductionAluminum is an extremely effective deoxidizer of molten steel; nevertheless, an efficient method of adding it to steel has eluded steelmakers for many years. It is well known that the recovery of aluminum used in the production of aluminum killed steel is both low and eratic, especially when the aluminum is added in the form of bars or lumps from chutes into filling ladles, a practice still common in many of today's steelmaking operations.As the density of aluminum is only about 40010 that of molten steel, it is conceivable that loose bars of aluminum simply ""thrown"" into a filling ladle will resurface before any appreciable dissolution of the aluminum has occurred, particularly if the depth of penetration of the additions is small. Before one can conclude that this is indeed the case, it is necessary to know the melting kinetics of an aluminum addition. Back in 1972, this information was not available; hence an extensive research program which focused on melting kinetics was initiated at McGill University."

Jan 1, 1982

By Shuo Zhang, Wenying Liu

"In dump leaching, the efficiency of metal extraction from ores is strongly influenced by the mechanisms of fluid flow. Particle size distribution acts as a fundamental parameter in the determination of fluid flow properties in packed ore beds. In this study, we investigated the particle size distribution in dump leaching by using image analysis technique. The results showed that the particles in the dump varied from smaller than 2 cm to larger than 200 cm in diameter. P80 was calculated to be 200 cm, which was significantly higher than the historical data used by the operation. P25, P50 and P80 were found to increase non-linearly with increasing depth towards the toe of the dump, suggesting the segregation of fine and coarse particles. The image analysis results were verified by applying the rock fragmentation models. The model with the Swebrec function was found to be in better agreement with the image analysis results. Future research will investigate the effect of particle size distribution on the behaviour of fluid flow.INTRODUCTION Fluid flow plays an essential role in the extraction of valuable metals using heap/dump leaching (Amos et al., 2009). The rates of the chemical leaching reactions and microbial activities determine metal concentrations in the leachates and therefore the efficiency of the metal extraction. The reaction rates are influenced by two fundamental processes: transport phenomenon and reaction kinetics (Bouffard & Dixon, 2001). The transport phenomenon refers to the percolation of fluids through channels and pores in a packed ore bed, which carries lixiviants and reaction products to/from ore surfaces by convection and diffusion. The percolation rate of the leaching solution is determined by the hydraulic conductivity of the packed ore bed, which is a function of the permeability and the degree of saturation (Guzman et al., 2008). Permeability, an intrinsic property of a packed ore bed, is strongly influenced by the particle size distribution of the ore grains (Bouffard & Dixon, 2001). Hence, the objective of this study was to investigate the particle size distribution in dump leaching."

Jan 1, 2017