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By Jae-Chun Lee, Sadia Ilyas

"The present study was carried out to develop an economically feasible and environmentally friendly technique to extract metals such as Al, Fe, Cu, Zn and Ni from electronic scrap by employing Penicillium chrysogenum strain KBS3. Studies were carried out in various leaching modes, including one-step leaching with combined growth and leaching phases (Mode 1), two-step leaching with alternative growth and leaching phases (Mode 2), spent medium leaching with separated growth and leaching phases (Mode 3), leaching with fresh growth medium without fungal culture (Mode 4), leaching with deionized water (Mode 5) and leaching with commercial organic acids (Mode 6). The main lixiviants produced in leaching Mode 1 were citric, tartaric, oxalic and gluconic acids in concentrations of 12, 2.5, 1.8 and 152 mM, whereas in leaching Mode 2, the concentrations were 15, 0.5, 1.0 and 1,162 mM, respectively. In leaching Mode 3, 63 mM citric acid, 23 mM tartaric acid and 29 mM oxalic acid was observed. At 5% pulp density, both leaching Modes 1 and 2 showed similar metal extraction yields from the electronic scrap at 35º C. Approximately 96% Al, 98% Zn, 48% Cu, 25% Fe, 66% Pb and 73% Ni were extracted in leaching Mode 1 in 14 days. In leaching Mode 3, 85% Al, 81% Zn, 97% Cu, 22% Fe, 50% Pb and 63% Ni were extracted in 14 days. The extraction yield of Cu was much lower in leaching Modes 1 and 2 (48- 50%) than in leaching Mode 3 (97%), as well as in leaching Mode 6 (98%) with organic acids, including citric, tartaric, oxalic and gluconic acids.IntroductionTechnical innovations in electrical and electronic equipment with new functionalities and designs stimulate consumer purchasing and lead a rapid increase in the production of waste materials. Terazono et al. (2006) have reviewed the data on electronic waste generation in different parts of the world. Studies by Bertram et al. (2002) have also affirmed that waste electrical and electronic components are the fastest growing waste category, which emphasizes the need for efficient recycling strategies. The recycling of electronic waste is an important subject, not only from the perspective of waste treatment, but also from the perspective of the recovery of valuable materials. However, the recycling of electronic scrap is still limited, due to the heterogeneity of the materials present in the products (Veit et al., 2005).Bioleaching-based processes offer a number of advantages over conventional pyro or hydrometallurgical methods (Lee et al. 2007; Lee and Pandey, 2012). These advantages include simple, inexpensive (in some cases) and ecofriendly approaches and the generation of less active leach residue relative to other metallurgical processes. Although biohydrometallurgical processes have been successfully applied to the leaching of metals from ores (Olson et al., 2003; Rawlings, 2002), data pertaining to the application of these processes for the extraction of electronic scrap are still scarce. Recently, a few studies have been undertaken for the extraction of metals from electronic scrap/ printed circuit boards (Brandl et al., 2001; Faramarzi et al., 2004; Ilyas et al., 2007; Ilyas et al., 2010). These studies were conducted with mesophilic chemolithotrophic bacteria (Acidithiobacillus ferooxidans and Acidithiobacillus thiooxidans), cyanogenic bacteria (Chromobacterium violaceum) or moderate thermophilic bacteria (Sulfobacillus thermosulfidooxidans). However, compared to bacterial leaching, fungal leaching has several advantages, including (i) the ability to grow at a higher pH, thus making it more suitable for the bioleaching of alkaline solid waste; (ii) a generally faster leaching process with a shorter lag phase and (iii) the chelation of excreted metabolites (e.g., organic acids) with metal ions, thus reducing toxicity to the biomass (Burgstaller and Schinner, 1993; Aung and Ting, 2005)."

Jan 1, 2015

By R. C. Rowe

THIS paper is an endeavour to analyse the ideal and practical functions of government technical mining services, and their relationship to the National Domain, as well as to one another. its spirit is not critical, even though at times it may appear to besoin fact. It is a serious effort to divert a trend in public thought which delights in calling itself practical whereas it is really merely short-sighted. The author refers particularly to the idea that governmental research is a luxury which should be curtailed in the interests of economy, and turned over to private enterprise or the provinces. In order that we obtain the proper perspective of the question, it is advisable to indulge in a little history. In the year 1842, the Geological Survey of Canada was formed under the guidance of William (later Sir William) Edmund Logan. The literature on the founding and history of the Geological Survey of Canada is extensive, and therefore it is unnecessary to go into detail here regarding it. It might be mentioned, however, that the Geological Survey of Canada is only seven years younger than the Geological Survey of Great Britain (founded in 1835), and is only exceeded in age on the American continent by the State Geological Surveys of New York, Pennsylvania, Massachusetts, and Michigan, which were founded between 1833 and 1836. In 1877, the Geological Survey became a permanent government institution as a branch of the Department of the Interior. It should be noted, however, that the Director of the Survey ranked as a Deputy Minister and reported direct to the Minister. This continued until 1907. In 1886, the Mineral Resources and Statistics Division of the Geological Survey was formed. Some years later, the Canadian Institute of Mining and Metallurgy (then the Canadian Mining Institute), backed by the mining press, began to agitate for the establishment of a Dominion Department of Mines, and in 1907 such a department was founded by the Geology and Mines Act of that year, with a separate Cabinet portfolio for the position of Minister of Mines.

Jan 1, 1939

By Anand Anupam

Conventionally, beneficiation in Indian coal washeries is done using dense medium cyclones upto the size of 0.5 mm. Coal fines below 0.5 mm size are extensively cleaned by froth flotation. There are many problems associated with flotation of Indian coals, e.g. poor response of coal particles to flotation, misplacement of fine high-ash material to froth, loss of good quality coarser coals (within ?0.5 mm size range) to tailing streams, high cost of reagents, water contamination, etc. In addition, sophisticated control systems for efficient management of the fines washing circuits are needed. Thus, there is an escalation in the capital and processing costs. In view of these facts, studies were carried out to establish the cleaning potential of dense medium cyclones for beneficiation of fine coal down to a size of 0.1 mm, essentially aimed at reducing the load on fine coal circuits mainly comprising of flotation. ROM Coal (in the size range of -2 + 0.1 mm) obtained from JogtaOCM,Jharia coalfield possessing relatively low ash (about 21%) was used in this study. Purpose for using low ash coal was to further lower, its ash content down to 8% which is comparable, to the ash content of imported coal. After characterization studies, nine tests were carried out on the prepared feed sample for its beneficiation using a dense medium cyclone of non-conventional design (very low cone angle and longer barrel), by varying its apex and vortex finder diameters. The efficiency of separation has been evaluated using Tromp curves. It could be established that it is possible to produce a clean coal of 8% ash, with Ep value of 0.044, using Jogta OCM coal by treating it in a modified dense medium cyclone. These results are summarized and discussed in detail in the present paper. Keywords: dense medium, cyclone, fine coal, beneficiation, Jharia coal

Sep 1, 2012

By Scott A. Anderson, Benjamin S. Rivers, Derrick D. Dasenbrock, Silas Nichols

Unknown geotechnical conditions are a major source of risk. Unexplored places vastly outnumber the sampled and tested ones, and widely spaced boreholes with intermittent tests and samples are the norm. Sometimes site-specific planning and thought goes into locating these special, tested places, such as basing them on the geologic understanding or anticipated key locations for the structure; more often they are simply evenly distributed. We demonstrate a holographic model that allows viewers to see real data in real space, scaled or not, and to visualize where measurements are taken, what those values are indicating, and where there exists more unknown and more risk. The holographic model shows in an intuitive way, values from Standard Penetration and Cone Penetration tests, and surface geophysics. The mixed reality of this future is that a wide audience – owners, designers, project managers, contractors, and stakeholders interact together in a real space where they see and talk to each other, while at the same time are individually looking all around below or above ground, like a gopher, in a virtual one. Risk in the future will be better managed through more thoughtfully designed investigations and better communication of 3D data in a world of augmented reality. INTRODUCTION This paper explores the use of augmented reality to convey understanding of the subsurface conditions of a bridge site. This is in contrast with the current state of practice where this information is contained in a geotechnical report, and the ideas are also applicable to other structures, earthworks, and excavations. “Augmented reality” describes a situation where a 3D holographic model is displayed for users in such a way that the users experience both the model and the real environment of their setting- such as at a desk, in a meeting room, or in an open space at a project site (Figure 1). The 3D holographic model is used to directly visualize underground features, to see through the earth to the actual locations where explorations are made, samples are obtained, or measurements are taken, design values are assigned, or construction is planned. An immersive model provides the following three powerful functions for users:

Jan 1, 2019

The effects of additives, sodium hydroxide, sodium carbonate, sodium oleate, oleic acid and polyacrylic acid, on stirred media milling of limestone have been investigated. The results are evaluated in terms of specific surface area, specific energy and energy efficiency as a function of additive dosage, polymer molecular weight, solids concentration and relevant operating variables. Use of additives generally results in changes in specific surface area and energy efficiency, while under certain conditions a more than 100% increase in these parameters can occur. Relevant interfacial properties have been measured and milling mechanisms involved are explored particularly in terms of the effect of additives on the flow patterns at higher solids concentration.

Jan 1, 1996

By Daniel Hiroshi Taira Anese

O objetivo desse trabalho consiste no estudo do grau de sensitização do aço UNS S31803 envelhecido a 700ºC por ensaios de reativação potenciodinâmica de duplo loop (DL-EPR). Para isso corpos de prova do aço em estudo foram solubilizados a 1175ºC e envelhecidos a 700ºC em tempos entre 10 min e 360 h. Corpos de prova metalográficos foram utilizados para caracterização microestrutural que foi realizada por meio de técnicas de estereologia quantitativa a partir de imagens de elétrons retroespalhados e análises magnéticas usando o ferritoscópio. Os ensaios DL-EPR foram conduzidos em solução 2M H2SO4 + 0,5M NaCl + 0,01M KSCN à 30ºC em amostras polidas. Observou-se que o comportamento eletroquímico do aço UNS S31803 possui forte influência da microestrutura, já que o grau de sensitização (GS) aumenta com o aumento do tempo de envelhecimento, devido à formação de fases intermetálicas que empobrecem as regiões adjacentes em Cr e Mo.

Aug 7, 2018

By Etiene Pereira de Andrade

Este trabalho avaliou a influência da deformação na formação de martensita e consequente resistência à corrosão do aço inoxidável austenítico AISI 304. O aço foi deformado em cisalhamento de 10%, 25%, 30%, 50% e 55% de deformação efetiva e em seguida mergulhado em solução contendo água do mar natural e artificial. As amostras imersas em solução de água do mar artificial exibiram aumento da massa enquanto as mergulhadas em água natural, redução. Esses resultados podem ser associados com a aderência inicial e estável de íons metálicos advindos dos cloretos, à superfície do material mergulhado em água do mar artificial.

Aug 17, 2017

By Cesar Giron Camerini

Os aços inoxidáveis bifásicos superduplex estão presentes em diversos setores da engenharia devido a versatilidade oferecida em termos de propriedades mecânicas e resistência à corrosão. Para garantir a qualidade destes aços, avaliar o teor de ferrita presente na microestrutura é de grande relevância para indústria uma vez que diversas propriedades do material dependem do controle deste teor. Durante a fabricação de equipamentos ou inspeções de campo uma das formas mais viáveis de monitorar o teor de ferrita é através do ferritoscópio, dada sua portabilidade e fácil interpretação. No entanto, observou-se que a forma usual de calibração do ferritoscópio pode levar a medidas imprecisas, principalmente na avaliação dos aços superduplex. A fim de analisar esta influência, foram realizados diferentes testes de caracterização microestrutural através de microscopia ótica, difração de raio-x e o magnetômetro de amostra vibrante, para confrontar com medidas obtidas com ferritoscópio. Conclui-se que para elevados teores de ferrita, a calibração do ferritoscópio realizada a partir dos padrões fornecidos pelos fabricantes apresentam desvios significativos dos teores encontrados a partir da caracterização com equipamentos de laboratório. O presente trabalho apresenta uma solução para utilização do ferritoscópio para uma quantificação mais acurada do teor de ferrita nos aços inoxidáveis superduplex.

Oct 30, 2017

By J P. van Dyk

A new crude ilmenite beneficiation process was recently proposed that allowed for the preparation of a smelter grade ilmenite from ilmenite with elevated chromium content. Magnetising roasting was not utilised in the process. As part of this circuit an ilmenite low susceptible reject stream was produced that had a low magnetic susceptibility. In this article a magnetising roasting process was investigated to beneficiate this material. Tests were conducted on material produced by pilot scale simulations on a typical South African East Coast heavy mineral reserve. The results obtained were compared to those published in literature for crude ilmenite. The small-scale experiments were used to define approximate operational limits for the oxidising roasting of a low susceptible ilmenite low susceptible reject stream, although industrial roasting conditions may differ significantly from those obtained in laboratory units. In a next phase these results will be confirmed on pilot plant scale.

Jan 1, 2001

By Stephen C. Tadolini

The Bureau of Mines conducted field investigations in two underground mines to determine the actual loads to which bearing plates were subjected when installed in conjunction with full-column resin-grouted bolts and the roof movements generated by the applied loads. Measured loads indicate that the bearing plate is an integral part of the support system. Vertical displacement gauges installed to monitor roof displacements in the test sites show that the highest degrees of loading occur in conjunction with the largest amounts of movement.

Jan 1, 1986

By J. B. Davis

Isotope analyses distinguish biogenic sulfur ores from non-biogenic ores, but do not distinguish bioepigenetic from biosyngenetic ores. Sulfur deposits of salt dome caprocks and of bedded Permian evaporites of west Texas, however, are clearly bioepigenetic. Anhydrite, introduced by salt diapirs into geologically younger sediments, is converted biogenically to sulfur and calcite in the presence of petroleum; for example, in Challenger Knoll, a salt dome at a water depth of 3600 m in the Gulf of Mexico. Bedded evaporites of west Texas in association with petroleum show an obvious epigenetic replacement of the anhydrite layers by biogenic sulfur and calcite

Jan 1, 1978

By M. Kumral, S. Hmoud

Optimising the configuration of infill drill holes is an important step during mineral exploration campaigns. However, this optimisation process encompassing all possible drilling configurations within a mineral deposit is highly combinatorial and hard to solve in a reasonable time. This paper proposes using spatial clustering algorithms to divide the orebody into contiguous zones and target the best zones with infill drilling in order to reduce the size of this optimisation problem. Several clustering algorithms are assessed in a spatial context on hypothetical datasets. This evaluation shows that the hierarchical density-based spatial clustering application with noise (HDBSCAN) algorithm can be used in combination with the uniform manifold approximation and projection (UMAP) dimensionality reduction algorithm to identify contiguous zones in the orebody.

Sep 1, 2021

By C. Dan Kealy

Recent antipollution legislation for the control of mine tailings and waste-water has required an increasing number of tailings ponds. Many of these new waste-retention ponds are being constructed in congested locations, or the older ponds have reached such a size that--if failure occurs--they pose a threat to human life and public property. Although the typical tailings-disposal embankment represents--to the casual-, observer or the economy-minded mine official--a rather ugly but benign and stable pile of waste, they are in fact an extremely sensitive structural mass, retained behind the frailest of dikes. Failure of the waste mass requires only a minor change in water retention or weather conditions, erosion or piping of the ground strata, shifts in load or slight earth tremors. When failures occur, the results can be disastrous. In the U.S., we have been fortunate that, so far, pond failures have not caused loss of life. Thus, failures in this country have attracted little public attention. Present tailings-pond construction methods used by the mining industry require the barest money investment, and little engineering effort. Unfortunately, this superficial approach may increase short-term profits, but the practice may be conducive to the construction of needlessly weak structures. In coming years many of these designs will probaly become corporate liabilities. A typical pond is portrayed in Figure IA. This particular pond in Arizona is 1 mile long and 3/4 mile wide. Illustrated in Figure lB is a representative pond in cross section. This paper in concerned with two basic features common to all tailings disposal: (1) location of the phreatic surface within a tailings-pond embankment because of its influence on embankment-slope stability, and (2) prediction of

Jan 1, 1971

By Amy Anderson

The Silica (SME) Technology has been utilized on three separate projects focusing upon the stabilization of mercury-contaminated materials: at the Mother Lode Mine in Oregon, the Sulfur Bank Mercury Mine in California and at a former chloralkali plant in British Columbia. Each of the projects relied primarily on the results collected via EPA Method 1311 TCLP, with additional tests such as SPLP, humidity cell tests and other supporting tests employed as well. Both technical and economic performance of the silica-based technology was evaluated as well as that of competing technologies in some cases. Results established that in each of the three projects an SME chemical dosage rate of 3% chemical by weight of soil/sludge was the optimal ratio required to achieve project treatment objectives, TCLP test results exhibited a reduction in the leachable mercury from the treated materials ranging between 75% and 99% as compared to untreated material, satisfying the technical objectives for each project, Project costs ranged from $l5.00 - $18.26 per metric ton.

Jan 1, 2003

By J. A. Halt, E. Larsen

"The Sydvaranger magnetite mine closed in 1996 due to low iron ore prices and was reopened in 2009. The flowsheet has remained more or less as in the old plant, based upon two grinding steps followed by magnetic separation. The magnetite is free of harmful elements and should be attractive on the high quality market. This requires a concentrate containing less than 2% SiO2, which previously was achieved by amine flotation. Amine was preferred because it could be used with sea water. The use of amine is now restricted by the Norwegian Climate and Pollution Agency. Therefore, testwork to replace cationic with anionic flotation was done. Activation of quartz with Ca or Mg ions prior to anionic flotation was shown by research from 1960 to 1980 to be effective under laboratory conditions. The old research results have been followed up in order to make a commercial process for Sydvaranger. Calcium activation works excellently with all Sydvaranger ores, including the ones containing amphibole minerals, but Ca activation requires the high and not environmentally friendly pH of 12.4. Magnesium activation at pH 10.5 is a little more challenging, because the maximum concentration of MgOH+ is about 100 times lower than that of CaOH+. Fortunately, the major impurity in the main Bjornevatn orebody is quartz, which responds well to Mg activation. The process does not appear to depend much upon water quality, as the silicates may already be activated during grinding and magnetic separation in recycled water. The new process is environmentally friendly, as only well-known household reagents are used; oleic acid or tall oil, dextrin, sodium hydroxide and magnesium chloride at pH 10.5.IntroductionThe processing plant of Sydvaranger Gruve AS (SVG) is located in the port town of Kirkenes in the northernmost part of Norway, 10 km by rail from the high-grade deposit of Bjornevatn. This plant has been able to beneficiate magnetite ore to up to 99.5% purity, as described by Sandvik and Malvik (2001). Using the magnetic properties of the ore and making the most out of its enviable liberation characteristics, the original plant consisted of ball mills and 600-mm magnetic separators. The plant was shut down due to market conditions in 1996 but reopened in 2009."

Jan 1, 2015

By R. L. Grayson

"Compliance standards for respirable dust, which are reduced because of high quart: concentrations, have become an industry-wide problem. Research on the physical and chemical character of quart-classified particles in respirable coal mine dusts indicates that they may exist in intermixed layers or may be coated by clay or coal material. The relative amount of intermixing varies with the coal seam being mined. If most of the quart: particles of a mine dust are ""pure,"" then the dust may have a high fibrogenic risk potential because of truly free silica and the compliance standard should be lowered. lf, however, quart: is locked inside another material matrix, or coated, a reduced compliance standard may not be appropriate.Although much research has been done on coal workers' pneumoconiosis (CWP) over the past decades, the etiologic agents of the disease still have not been pinpointed. The predominant methods of characterizing respirable coal mine dusts were bulk analysis techniques for determination of elemental and mineralogical concentrations, the results of which were used in statistical analyses to determine relationships between dust composition and the occurrence of CWP. These methods are incapable of finding the etiologic agents in the dust primarily because of complicated and confounding physiochemical factors, which may be discovered if the focus of characterization was done on a dust particle level.The SEM/EDXA-based research discussed here shows a significant difference in the number of ""pure"" quartz particles in respirable dusts collected from different mines. Some of the results have been reported previously (Grayson, Andre, and Simonyi, 1988). Concurrent research by other investigators (Wallace et al., 1989) demonstrates an SEM/EDXA-based methodology to pinpoint the location of the ""contaminating"" substance(s ) in a quartz-classified particle. The research of the European Economic Community has also begun analyses on the respirable-dust-particle level (Robock and Bauer, 1988).Since the compensatory and intangible costs of CWP are substantial in the United States, it is important that the etiologic agents be determined and then either controlled or neutralized in a cost-effective way. This line of research is especially important consid-ering the forecasted. near-term growth of coal production and the evolution of high productivity longwall panels (an immediate problem in compliance) and continuous mining sections ( a probable future problem).This need has been accentuated now that nearly all respirable dust samples submitted to MSHA are analyzed for free silica (Tomb, Parobeck, and Gem, 1986). Today a real problem exists in the coal industry, both underground and surface, because of high quartz levels in respirable dusts causing substantially reduced compliance standards (Murphy, 1989).The combined results of the respirable dust particle investigators indicate that conventional bulk sample analyses may not faithfully represent the amount of biologically available or active quartz in all mines with a high level (greater than 5% ) of quartz in the dust For example, some mine dusts might contain predominantly occluded (or coated) quartz particles where bulk analysis would result in anomalously high ""free silica"" measurements. The same result would occur when quartz particles are intermixed substantially with other minerals that can alter the surface of the composite particle away from a quartz-behaving character."

Mar 1, 1992

By Santiago Gómez, Pablo Segarra, José A. Sanchidrián

In-hole detonation pressure measurements are unusual in the production environment of a mining operation, partly owing to the hostile conditions to which recording equipment and pertinent probes must be subjected and, partly by the constraints of the production cycle. In recent decades, detonation pressure measurement techniques have been developed using low carbon resistors (LCR)-based gauges. They are cheap, relatively easy-to-operate, robust and with a high percentage of success in both open-pit and underground mining. Detonation pressure measurements are extremely important when carrying out numerical modelling to simulate explosive induced vibrations, since simulation results are highly dependent on the pressure-time history applied on the blasthole wall. Analytical equations have typically been used to model the pressure-time history; however, they usually do not adequately represent the behaviour of the explosive in terms of: peak pressure reached, rise time, mean frequency, decay and shape of the signal. Experimental records may be directly used instead of utilizing synthetic signals if they are available. In this work, (LCR)-based gauges are used to measure detonation pressure inside a production blasthole. The operation principle of the gauges utilized and the instrumentation layout is described in detail. A flexible resolution USB oscilloscope with high sampling rate has been used to catch the elusive pressure peak event. Measurements were carried out in production blasts fired with ANFO (0.86 g/cm3) in an underground mine––this also includes velocity of detonation (VOD) records––. A procedure based on the shock impedance matching has been developed to calculate the detonation pressure due to the characteristics of the gauges prevent its direct measurement. Detonation pressures obtained range from 1.71 to 2.97 GPa (248.01 to 430.76 ksi) which are in line with pressures calculated from the VOD records. Mean frequency and rise time analysis shows that 2 of 3 signals cannot be described using typical analytical equations.

Feb 6, 2023

By S. G. Zahony

The Moris gold deposit resides in a massive ridge-forming sulfide-poor epithermal quartz and calcite vein system and consists of a mineable reserve of four million tons of 2.1gm Au/ton. Post-mineral normal faulting along the hanging wall of the main fissure has caused a hogback-like exposure of the vein, allowing for inexpensive opencut mining. The vein formed between pre-Cretaceous(?) phyllitic clastic sedimentary units in the footwall and Tertiary andesitic volcanic rocks in the hanging wall. Part of the ore reserve is hosted in a Tertiary conglomerate that rests unconformably atop the phyllitic footwall sequence. The original unoxidized vein material contained substantially less than 1 gram Au/ton. A four-fold upgrading of gold occurred by enrichment when gold recrystallization took place in the electric fields of oxidizing pyrite cubes.

Jan 1, 1993

By T. S. Grewal, S. C. Gupta, H. Natarajan, T. W. McQuade, N. Nejibulloev-Mamedov

Cigar Lake is one of the world’s largest high-grade uranium mines. The ore mined at Cigar Lake is milled at Orano Canada Inc’s (Orano) McClean Lake mill. The average Cigar Lake ore uranium grade since the start of mining activities in 2014 is 17.8% U (range 8– 28%). To achieve budgeted production of 18 M lbs U3O8/yr the required average feed tonnage to the mill is about 45 kt/yr. Arsenic, occurring as arsenides and sulpharsenides, is one of the major elements of concern associated with Cigar Lake ore. The leaching process is a sulphuric acid leach under oxidizing conditions at near atmospheric pressure. The presence of arsenic in the ore consumes oxidant in leaching as well as ferric sulphate in tailings preparation for arsenic sequestration. The average arsenic grade since the start of mining at Cigar Lake is 0.57% As. Further, the ore is hosted in a matrix of sandstone and clay, which results in poor settling in CCD. The average uranium grade for the balance of Cigar Lake Phase 1 ore is expected to drop to 12.5% U and the average arsenic grade is expected to increase to 1.6 % As, with an annual average peak of 2.5%. Therefore the tonnage throughput required to sustainably meet the production target will increase to 55 kt per year. Orano partnered with Hatch Ltd. (Hatch) to perform a gap analysis study to identify key circuits and equipment in the mill that would require debottlenecking. A METSIM mass balance model of the McClean Lake mill was generated and validated with actual mill operating data. Various feed scenarios were then studied, and the outcome was a traffic light table, which highlighted feed scenarios that exceeded installed capacity of major equipment and circuits. The results provided the basis for the PDC for the pre-feasibility study. This paper will outline the results of the gap analysis, the mass balance model, the feed scenarios and the study undertaken to prepare the McClean Lake mill for the change in ore quality from Cigar Lake.

Jan 1, 2020

By Joerg Hammerschmidt, Marcus Runkel, Andreas Wirtz, Kent Pope

"Fluidized bed reactor systems in the minerals industry have been progressively developed and widely implemented over a period of more than sixty years for a multitude of process applications. Their versatility is manifested in calcining, roasting and combustion treatment of minerals including solid fuels. Experiences from metallurgical processes have expanded to new applications in the oil shale processing, biomass combustion and renewable energy sector. This paper focuses on the most important aspects of fluidized bed technology for a variety of Outotec processes. Energy recovery is a major topic for all applications and will be addressed, as well as environmental aspects, particularly regarding the off-gas treatment. Outotec is one of the pioneers of roasting and the fluidized bed process including gas cleaning and sulphuric acid production where applicable. Process development is strongly supported by significant investment in R&D, thus enabling process adaptation and scale-up to meet specific customer/market requirements.Introduction to Fluidized Bed TechnologyThe early days of fluidized bed technology were characterized by the use of bubbling fluidized bed reactors (BFB). This technology was popular for roasting zinc and copper ores. The introduction of circulating fluidized bed technology led to increased plant capacities and improved process control for the traditional processes. Furthermore, the technology has been applied in many other industries, including the renewable energy industry, which will be part of this design and process comparison. The paper starts out with the fundamentals on particle fluidization as the main common design parameter, leading to the importance of heat recovery and offgas treatment.In fluidized reactor systems, the particle concentrations can reach several hundred kilograms per cubic meter of fluidization gas. This high solid concentration leads to large surface areas and enables direct contact of gas molecules with particle surface molecules. Excellent conditions for enhanced heat and mass transfer thus provide nearly ""ideal"" heat exchange conditions and better reaction kinetics. The bubbling bed exhibits a better heat transfer coefficient within the bed in comparison to the circulating fluidized bed (CFB). The different conditions of gas velocities and solid concentrations allowing the classification of fluidization reaction regimes are shown in the Reh diagram in Figure 1."

Jan 1, 2014