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By J. Stachulak

In recent years more emphasis has been placed on the control of nitrogen dioxide (NO2) emissions from mining diesel equipment. Worldwide, diesel engine regulations to control emission and protect the environment are also driving the development of the diesel engine technology to reduce oxides of nitrogen NOx (Nitric oxide, NO + NO2). NOx are toxic gases produced in mines during the operation of diesel equipment. Most of the diesel equipment used in underground operations are equipped with Diesel Oxidization Catalysts (DOCs) designed to reduce carbon monoxide (CO) and hydrocarbons (HC). The effects of DOCs on NO2 production from diesel powered equipment is not well understood. DOCs do not alter NOx concentration, but may promote the oxidization of engine exhaust NO to the more toxic NO2, thus increasing the undesirable NO2 exposure of workers in the mine environment. In 2012, the ACGIH reduced the NO2 TLV concentration value from 3 ppm to 0.2 ppm. Vale and CanmetMINING have been involved in several research projects to reduce diesel emissions exposure to workers. One aspect of the current program is to determine the effects of in-use DOCs on NO2 production. Several in-use DOCs taken from mining equipment were selected for testing in the laboratory using ISO 8178-C1 and mine LHD transient test cycles. The paper presents the laboratory test results and effects of DOCs on NO2 production. The results indicate significant reductions in CO concentration, by over 77%, while increases in NO2 varied from 46% to 315% based on the ISO 8178-C1 8-mode steady state test cycle. The mine LHD transient test cycle showed the same pattern, although the magnitude of CO reduction was less. Consequently, it is recommended the use of only those DOCs that have been properly evaluated and shown not to significantly increase NO2 emission in the environment be used on mine equipment.

Aug 1, 2013

By D. C. Brady

"Within six months from award of a project management contract, Les Mines Dumagami Limitée, Cadillac, Quebec, was operating its new hoisting facility. This was accomplished with less than a six-week shutdown of mine production while still maintaining shaft access for underground maintenance.The work involved installing a refurbished /3.5 ft diameter double drum hoist, replacing a timber headframe with a newsteel headframe, increasing the ore bin capacity from 500tons to 1000 tons, constructing a new substation, and upgrading related facilities.This paper describes the work and methods used by various contractors, Les Mines Dumagami Limitée and J.S. Redpath Mining Consultants Limited to bring this project to a successful completion. It discusses the history of the project from proposal stage through to the design, procurement, scheduling, and construction management. The paper also comments on problems that were encountered and the methods used to overcome them.IntroductionThe Donald J. Laronde Mine of Les Mines Dumagami Limitée (Dumagarni), a gold and copper producer, is located in northwestern Quebec, approximately half way between Val d'Or and Rouyn. The mine started production in the spring of 1988 and the first gold bar was poured in June 1988.Following a request by Dumagami, on February 22, 1989, J.S. Redpath Mining Consultants Limited(Redpath) delivered a proposal to increase hoisting capabilities from 1500 tpd to a minimum of 2500tpd. Although various concepts were considered, Redpath proposed a new hoist house along the same shaft axis as the existing hoist, and located on the site of the existing substation. They would then provide a new substation, replace the headframe with a largersteel structure , gain extra storage capacities by increasing the bin heights, and raising the roof of the bin house accordingly.Although underground mining would have to be stopped for a month, the mill production would be maintained by feed from Dumagami's open pit.Figure 1 shows the original plant layout and Figure 2 represents the general arrangement after the project was completed . Table 1 compares the original hoisting facilities to the new facilities.On March 2, Dumagami awarded Redpath a contract that included preliminary engineering, detailed engineering, procurement and contract administration, and later added construction management. The preliminary engineering refined the initialconcept, selected major equipment, and prepared schedules and capital cost estimates for the total project."

Jan 1, 1991

By A. B. Parsons, P. G. Howes

"This article discusses how recent changes in the federal and Quebec .income tax laws have contributed to an improved investment climate for mineral exploration in the Province of Quebec. Individual investors who are resident in Quebec and who are in the highest tax bracket (1984-60.4% marginal rate) may obtain tax benefits that result in only nine cents of each invested dollar being at risk.IntroductionIn a recent submission by the Mining Association of Canada to the Royal Commission on the Economic Union, it was stated that the mining industry ""is no longer discovering and opening new mines at rates sufficient to offset the depletion of existing orebodies and to maintain pre sent output"". With world metal prices still in a depressed state following the prolonged 1981-82 recession, moreover, the continuing success of Canadian mining in world markets will depend on this country's ability to compete in a new environment characterized by subsidized Third World production . For the most part, this new competitive environment will encourage the development of cost-efficient mines that are better equipped to withstand the troughs and valleys of international metals prices."

Jan 1, 1984

By A. Elsayed

Lightweight metals such as magnesium show potential in replacing aluminum alloy castings for engine cradles, cylinder heads and transmission cases. Unfortunately, magnesium alloys are susceptible to entrapping oxides and other impurities during casting that hinder strength and ductility. The current study examined various filter sizes and configurations with the aim of improving the mechanical properties of permanent mould cast AZ91E. The unfiltered casting had a yield strength, tensile strength and ductility of 93.3 MPa, 153.3 MPa and 2.2 % respectively and increased to 96.5 MPa, 167.0 MPa and 3.1 % with the use of a fine mesh filter within the well of the mould. The increased strength and ductility was likely due to the filtered castings containing fewer inclusions on their fracture surfaces as compared to the unfiltered castings.

Jan 1, 2011

By Grant Small, Jessica Kinal, Christopher J. Greet

"The conversion from an electrochemically reactive grinding media (forged steel) to a more electrochemically inert alloy (high chrome white iron) not only reduces the wear rate of the grinding media, but also has an impact on the grinding chemistry. Typically the grinding chemistry becomes more oxidising, with less reducing Eh values and more dissolved oxygen in the pulp. There is also a decrease in the EDTA extractable iron, which is an indication of the change in the media corrosion. These changes are indicative of alterations in the surface chemistry of the minerals that the operator is trying to separate. For porphyry copper ores the changes in the pulp and surface chemistry not only affect the copper sulphide minerals, but also impact the iron sulphides (i.e. pyrite and pyrrhotite). Generally, with more oxidising pulp chemical conditions during grinding there is an increase in the oxidation of the iron sulphides which renders their surfaces hydrophilic, thereby depressing flotation. This leads to improved selectivity for copper sulphides against iron sulphides.INTRODUCTIONPorphyry copper deposits are the dominant source of copper that is mined today to satisfy global demand. These style of deposits typically contain one percent copper mostly as chalcopyrite, but may contain other copper bearing minerals (for example, bornite, chalcocite, azurite, malachite), small quantities of pyrite and quartz. Porphyry copper deposits also contain economically significant quantities of gold, silver and molybdenum. Interestingly, the majority of the world’s porphyry copper deposits are concentrated along tectonic plate boundaries (Figure 1)."

Jan 1, 2016

By Amir Asadi

Various damage modes that evolve with time in polymer composite laminates, such as transverse cracking, vertical cracking, delamination, and fiber fracture, as well as the interaction among them, influence the time-dependent degradation in modulus (creep) and strength (creep rupture) of polymer composite laminates. This study is focused on modeling the time-dependent evolution of transverse cracking in [90] plies of a multidirectional polymer composite laminate [0m/190n]. This model uses a two-dimensional variational analysis to determine the stress state at any given creep time. The elastic stored energy, determined using this stress state, is compared with a critical energy for fracture to determine the crack evolution with creep time. Model predictions are compared with experimental results to validate the model.

Jan 1, 2010

By A. Danaei, A. McLean, M. Barati, C. Ravindran

"The aluminum industry generates about 90 million tonnes of red mud each year. Previous research shows it could be utilized as a refining flux with a high capacity to absorb phosphorus and sulphur from hot metal in the steel industry. The present study was undertaken to evaluate the melting properties of such fluxes, as it affects the effectiveness of the flux. The results show that the melting behavior of red mud is strongly affected by lime addition and the characteristic melting/softening temperatures reach minimum VALUES (at 32.7 wt% CaO. From these findings, a correlation was established between melting behavior and optical basicity. This allows one to adjust the composition of the flux based on the process requirements. INTRODUCTIONThe aluminum industry generates about 90 million tonnes of bauxite residues each year. This residue is usually red in color because it contains a substantial amount of iron oxide. The red mud, as it is called, is a solid waste with a high concentration of sodium oxide, high pH (10 to 13), and high alkalinity, and thus is harmful to many forms of life. Traditionally, the material is stored in large tailings ponds within the plant’s vicinity (Power, Grafe, & Klauber, 2009). Development of solutions for safe disposal or preferably using this residue for other industrial processes or applications could help restore polluted locations and eliminate a negative impact on the environment (Haake, 1988; Power et al., 2009; Yan & Xuegong, 2010).The mineralogy and chemical composition of red mud depends on the quality of the bauxite and refining process parameters. In general, it consists of iron oxide (Fe2O3), aluminum oxide (Al2O3), titanium oxide (TiO2), sodium oxide (Na2O), silicon oxide (SiO2), and calcium oxide (CaO) (Power et al., 2009). Like most ores and soils, bauxite can contain trace quantities of metals such as arsenic, beryllium, cadmium, chromium, lead, manganese, mercury, nickel, and naturally-occurring radioactive materials, such as thorium and uranium. Most of these trace elements stay in the residue (Power et al., 2009)."

Jan 1, 2012

By Tassos Grammatikopoulos

The St. Lawrence deposit is a large wollastonite skarn (ca. 9 Mt @ 41.3% wollastonite) adjoining the gabbroic-to-syenitic Leo Lake pluton in the granulite facies of the Frontenac Terrane of the Grenvillian Central Metasedimentary Belt. It occurs within a horseshoe-shaped horizon of quartzite, open to the east. The skarn extends over 1.2 km2, and comprises wollastonite-dominant, wollastonite-clinopyroxene, and diverse quartz-feldspar-sulphide (-titanite) layers, interbanded with, and strongly folded within, the quartzite. As in the world-class wollastonite deposits of the Willsboro district, New York State, no carbonate protolith is preserved and calcite is a negligible constituent of the mineralized zones. Wollastonite development is nonetheless ascribed to metasomatism of a metacarbonate unit by magmatogene, silica-rich, CO2-poor (XCO2 < 0.05) fluids, at P = 350 MPa and ca. 560 oC, or, alternatively, 550 MPa and ca. 630 oC. Several high grade zones, averaging >40%, but locally exceeding 80%, of translucent, white, tabular wollastonite grains, with lengths of 0.2 - 2 cm, have been delimited by drilling. Preliminary beneficiation studies yield high aspect-ratio and high-purity (low Fe and Mn) concentrates. St. Lawrence compares favourably to other known prospects and operating wollastonite deposits; having good chemical and physical properties, low iron content, and high aspect ratios (>20:1). In addition, the deposit has a favourable size and location, and will benefit from a low Canadian dollar. Canada currently has no wollastonite production.

May 1, 2002

By McNeely DuBose

INTRODUCTORY PROSPECTING for aluminum has always been, and still is, a peculiar combination of the technical with the physical approach, and 1 want to explain my conception of the term &apos;prospecting&apos; when applied to aluminum, which differs in some respects from the ordinarily accepted idea of prospecting. In the early days of gold mining, prospecting was a search in the hills and the river beds for the metal, not for its chemical combinations. And so it was in the early days of aluminum, with the difference that the search for the metal was carried on, not in the hills and dales, but in chemical laboratories. Aluminum is never found in the elemental state and at that time the metal bad never been seen, but scientists of that day bad forecast that such a metal must exist and in 1807 Sir Humphrey Davy went so far as to give this unseen metal a name, aluminum, from the Greek word alumen. This word applies to our alum, and it was from alum that Davy sought to produce the metal. It is strange to think that, in laboratories throughout England and on the continent, prospecting for aluminum was busily under way by men who had never seen the metal they were searching for. Their situation was something like that of the fisherman and the &apos;big one&apos; that got away. They could describe the metal, give its exact weight, and even name it, but they could not produce visual evidence of its existence. Eventually, however, the efforts of the scientist &apos;prospectors&apos; were rewarded and in 1826 the metal was actually produced, possibly first by Wohler, though Oerstedt, a Danish chemist, is usually credited with the achievement.

Jan 1, 1951

By Michel Gauthier, Pierre Marcoux, Gaétan Morin

"The recent opening of Muscocho&apos;s gold mine at Montauban, as weil as the discovery of several new copper-gold showings of a similar nature near the confluence of the Saguenay and St , Lawrence has revealed the existence of a new metallogenic gold province which is located within supercrustal units of Helikian age within the Grenville Province. Three metalliferous belts have been identified, each one of which is related to a series of SW-NE trending faults. The first is located in southeastern Ontario and southwestern Quebec. The second extends from the Balmat-Pierrepont mining district of New York State up to the Lac St. Jean region of Quebec, and includes the Montauban camp. The third follows the St. Lawrence river in Charlevoix County and along the north shore of the Gulf of St. Lawrence.The gold mineralization which is present in the central portion of the Grenville Province is of two types: either stratiform or vein. Deposits of the first type, of which the Muscocho is the type locality, are economically the more interesting of the two. Not only is this mineralization stratiform, but also shows a distinct affinity to AI-rich, Mg-rich or calc-silicate-rich bands. As is the case with the Bousquet and Hemlo regions of the Superior Province, they are associated with layers which are rich in sillimanite and occasionally staurolite. A second parallel between the Bousquet and Montauban deposits might be the presence of manganesian gamets, which have been recognized at the two localities. Some of the mineralization in the central Grenville Province is located within thin bands of iron formation which are rich in arsenic.The stratiform gold deposits of the central Grenville Province are of exhalative origin and are located within a volcano-sedimentary terrane. It is probable that a part of the gold present in these Helikian deposits have been derived by remobilization of Archean mineralization. The vein showings form as a consequence of the remobilization of the Helikian strata during the Grenville metamorphism,"

Jan 1, 1985

By C. Bourgoin

"The factors constraining productivity in the mining of narrow vein ore deposits are numerous and often interdependent. This paper concerns mining techniques capable of reducing some of these constraints in the case of vein deposits whose dip is less than 45 degrees. Modifications of conventional mining methods as well as suggested new developments are presented, as are matters pertaining to the mechanization of operations as a mean of increasing both productivity and work safety. IntroductionThe mining of vein deposits, whose width (thickness) is generally less than 2 metres and whose dip is often variable, calls for the use of varying stoping procedures as well as appropriate infrastructure and equipment. In the case of intermediate dips (15 degrees to 45 degrees), it is generally conceded that the degree of mechanization is limited and that ore removal via gravity is impossible. This paper proposes certain innovations in matters of equipment use and stoping methods, together with certain technical data pertaining to the application of these new procedures Stoping MethodsTo mine vein deposits, one must choose a method that can adapt to irregular ore limits and allow, as well, for good ore recovery with as little dilution as possible. In addition, it is important to minimize development work in waste rock. In principle, one selects a method that is both safe and profitable; this method will be defined mainly by the nature of the vein deposit and its dip, by the competency of the rock formations and by certain technical considerations. Moreover, the stoping procedure in a given deposit may well change with time as a function of new layouts or new equipment."

Jan 1, 1994

By D. J. Xue

Four kinds of coal-rock combination were subjected to three kinds of stress waves in the SHPB numerical simulation. The wave propagation and the changes of the strain energy in the coal-rock combination during the dynamic impact process were recorded as well as the contact force. The dynamic response law of coal-rock combination was obtained. It was found that the coal had better reflectivity than the rock because of coal with larger impedance. In contrast the rock had better transmissivity. As the crest value of the incident wave increased, the increment in the crest value of the transmitted wave weakened in the coal-coal group, coal-rock group and rock-coal group, in contrast, the increment in the rock-rock group increased.

Aug 1, 2013

By A. Himsley

This paper presents a review of the existing ion exchange resin systems for treating unclarified pregnant liquor, with particular reference to uranium extraction. A new concept of a truly continuous ion exchange system is described and operating details are given,of a 0.6.-m (24 in.) diameter pilot plant treating unclarified acid leach liquor.

Jan 1, 1977

By Farnham. G. S.

It is difficult co know how to deal with this subject before a group having such mixed interests. The mining man is not coo concerned with the problems of alloy research. The engineer is more interested in properties of materials than how these properties can be achieved. The business man feels that scientific history and prognostication are not for him, predicting trends or possible developments in the economic field being a more than sufficient occupation. Yet the application of physical metallurgy research to industry is of importance to miner, engineer, and business man, for only through such application can the continuing existence of industries manufacturing or consuming metals be assured. History shows that hard work does not guarantee industrial survival. For instance, the Bessemer method of steel making superseded puddling operations; it, in its turn, has been largely displaced by open-hearth processing; later, steels made in electric-arc furnaces displaced open-hearth products in the quality field; and now, very specialized steels are being made in high-frequency rather than in arc furnaces. It is apparent then, if industry is co remain healthy, complacency must give way co imaginative planning, based on a thorough knowledge of production technique, a knowledge supplied by efficient research.

Jan 1, 1947

By Sang-Kyun Woo

The electric power conduit (EPC) in Korea has been constructed since 1978. Facing the challenge of safety and sustainability of the EPC, it is urgent to develop an inspection strategy and maintenance system for the structure based on the concept of life-cycle management. This paper introduces the newly developed mobile inspection and diagnostic system of the EPC. The novel aspect of this particular system is the integration of non-destructive mobile inspection techniques with BIM (Building Information Modeling) and LBS (Location-Based Service). BIM is an ideal tool and platform for developing an inspection and diagnostic system, and RFID (Radio Frequency Identification) is a useful tool to construct USN (Ubiquitous Sensor Network) for LBS. The goal of this research is to establish an EPC inspection and diagnostic system concept based on BIM and LBS using RFID. In this research, a BIM model of OPENTBM tunnel for EPC will be established to show the integration of 3D CAD with the inspection data. An EPC?s maintenance database, which includes the deterioration types of the structure, inspection records, and repair methods, was designed to interact with the BIM. The system will be implemented by the BIM with the related database, in which the construction geometry and all related information are stored. The proposed system was designed to utilize the inspection and diagnostic system under the USN environment using RFID in EPC directly.

Aug 1, 2013

By K. S. Raja, B. McNall, B. Pesic

"High-level radioactive wastes are stored in large underground storage tanks made of low-carbon steel. The wastes consist of concentrated solutions of sodium nitrate (NaNO3) and sodium hydroxide (NaOH), and the radionuclides 137Cs, 99Tc, and 90Sr. The corroding steel microenvironment may produce localized reducing or oxidizing conditions that affect the solubilities of the species such as Tc(VII) and Tc(IV), which in turn modifies the kinetics of corrosion of the storage tank. To understand the influence of technetate ions on the corrosion of steel, electrochemical polarization studies of A 537 steel samples were carried out in 1 M NaNO3 + 0 .05 M S r(NO3)2 + 0.1 M NaOH with and without addition of HReO4 at different temperatures (24 – 85 °C). The concentration of HReO4 was varied from 0.014 – 0.04 M.INTRODUCTIONAqueous processing of spent nuclear materials generates a large amount of high-level radioactive wastes. The wastes are primarily salt solutions of sodium hydroxide and sodium nitrate which also contain fission products such as 137Cs, 99Tc, and 90Sr. Among the high level radioactive fission products, Tc-99 is of great importance because of its high concentration, long half-life (2.1 x 105 years), high solubility in geologic waters as technetate, and rapid diffusivity through the geologic systems. The solubility of technetate ions varies depending on the oxidizing conditions prevailing in the storage containers. High level radioactive wastes are stored in single shell or double shell tanks made of low carbon steels such as ASTM type A15, A516-70 and A537. Most of the available literature on corrosion of steel in simulated radio active waste environments pertains to nitrate induced stress corrosion cracking (Subramanian & Mickalonis, 2005). The corroding steel microenvironment may produce localized reducing or oxidizing conditions that affect the solubilities of the species such as Tc(VII) and Tc(IV). Corrosion of steel and formation of Fe(II) and Fe(III) will affect adsorption and reduction of Tc species. The radioactive species can irreversibly be sorbed on the steel surface by oxidation of Fe(II) to more stable Fe(III) and fixed as less soluble Tc(IV)/Fe(III). The solubility of Tc species is also affected by other factors such as dissolved oxygen, local pH, temperature etc. How the corrosion behavior of steel will be affected in the presence of Tc species is not clearly understood.Cartledge (Cartledge, 1960) demonstrated that passivation of iron can be achieved in the presence of oxygen along with suitable inhibitor ions/molecules of the general formula XO4 n-, such as pertechnetate (TcO4 -). The pertechnetate ion is univalent. Since it is derived from a strong acid, no buffering action can be expected from this ion. The redox potential of the reaction (1) is 0.738 VSHE (Pourbaix, 1974)."

Jan 1, 2012

By J. S. Stewart

THIS paper was prompted by a persistent demand for what information we have that will throw light on the oil and gas possibilities of the Maritime Provinces. The problems involved were made familiar to the writer during three seasons of field work in New Brunswick and Nova Scotia. The reasons for renewed interest are: (1) In many parts of that region, the surface is underlain by a thick series of unaltered sedimentary rocks. (2) Oil seepages occur, and oil in commercial quantity has been exploited&apos; near Moncton, New Brunswick, for many years. (3) In recent years, a new method of attack has been developed toward the finding of stratigraphic traps. This method is based on a detailed study of the geological history of the region, as revealed in surface outcrops and samples from deep wells. The well samples show the lateral variation of strata, far from any possible surface outcrop of the same beds. Sufficient work has now been done in the Maritime Provinces to reveal the broad features of the geological history and the character and distribution of the various rock formations. Comparatively little deep drilling has been done in this region, but the holes are widely scattered and the samples from them have added much to the information obtained from the numerous outcrops of bed-rock. The following discussion gives a summary of available information that has a bearing on the subject.

Jan 1, 1943

The University of New South Wales (UNSW) has been a world leader in the development of innovative virtual reality technologies over the last 10 to 15 years. These developments have included developing the world?s first 360° surround, virtual reality (VR), stereo projection theatre system known as AVIE (Advanced Visualisation and Interactive Environment), which was developed by iCinema, a collaborative venture between the UNSW Faculties of Engineering and College of Fine Arts. The UNSW School of Mining Engineering has been responsible for development of mining applications virtual reality software modules and to date, has developed eighteen different mine safety training and mining engineering education modules which run in the AVIE environment. This platform and technology package provides a unique ?immersive environment? experience for groups of trainees or students who can engage with the simulated environment in the complete safety of the virtual reality theatre. In all of the major international mining industries, safety is of paramount importance, and training of personnel is an essential component of any comprehensive proactive safety management system. All personnel need to be aware of the inevitable hazards around them at all times, as well as understand appropriate safety and operational procedures. This can be done by conventional class-room style training sessions, or by provision of training documentation. However the effectiveness of such systems is often very limited due to the inability of trainers to engage with the audience for a lengthy period of time; or to convey the often complex and variable mining environments and situations which can exist in a typical mine. The ability to immerse the trainees in a virtual mine environment, with all the reality of an actual mine but with none of the physical exposure to actual hazards, provides a far more effective and engaging training experience. Furthermore, in the virtual world, trainees can be exposed to the very unlikely, but nevertheless high consequence hazards such as mine fires, falls of ground or outbursts, without any risk to their safety and well-being. The end result is that trainees will be far more engaged with the learning environment they find themselves in, and will develop a far higher level of understanding of the topics, rather than simply experiencing a passive class-room style learning environment offered by conventional training modes. The UNSW systems have been implemented widely within the Australian mining industry and the mining engineering education sector and are now being adopted internationally. This paper presents an overview of the innovative technologies involved in these virtual reality systems ? as applied to the mining industry. Modules developed for both mineworker training and mining engineering student learning will be presented, to illustrate the effectiveness and value of such a training and education approach.

Aug 1, 2013

By Janos de Warga

"After a short introduction to the history of the semi-conductor theory, the paper describes the principles of electron and hole flow in the semiconducting materials, the operation of the PN junction, and the rectification process in multi-layer devices (diodes and SCR's). The various methods of purification and zone-refining of the silicon are illustrated prior to the discussion on the most commonly used junction-forming processes (alloying, diffusing, etc.). Modern device fabrication and packaging operations are illustrated. Factory testing, evaluation, electrical parameters and guaranteed rating characteristics are listed. It is explained in this paper how the various device parameters affect the electrical performance of the finished unit and how the finished unit characteristics (turn-on, turn-off time, etc.) will influence the equipment rating. In concluding, some typical items of equipment are highlighted, and the applications of these semiconductor rectifiers in the chemical, mining, pulp and paper, and steel industries, etc., are dealt with."

Jan 1, 1967

By W. McCombe, G. Remple, L. Nightingale-Mercer

The McClean Lake Mill is located approximately 850 kilometres north of Saskatoon, Saskatchewan, Canada, and is operated by Orano Canada Inc. (Orano). The mill was designed to process high grade uranium ores, and a multi-year expansion was completed in 2014 to increase its production capacity to 24 Mlbs U3O8 per annum. The mill also underwent various upgrades to allow it to safely transition from processing low grade ores to high grade ores from the nearby Cigar Lake Mine. During the metallurgical test work on the Cigar Lake ores, it was identified that some ore zones of the deposit have a propensity to generate hydrogen gas during acid leaching. Hydrogen is a volatile and explosive gas, which poses obvious safety concerns in the leaching circuit. Uranium processing is further complicated by the fact that an oxidant in the form of oxygen gas or hydrogen peroxide is required to regenerate iron in the leach, which further increases the risk posed by hydrogen gas. During 2013 Orano and its consultant Hatch designed and engineered several novel upgrades to the leaching circuit to mitigate the risk of hydrogen gas evolution in the process. Best in class technology was utilized in addition to control and operating strategy changes to ensure the leaching circuit could be safely operated with ores that evolve hydrogen gas. This paper reviews the design concepts and modifications implemented on this unique and challenging project, and also provides an update on the operational reality of hydrogen in the circuit gained through five years of operational experience with hydrogen evolving ores.

Jan 1, 2020