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By Y. L. Mehta

The working experience of the Zinc Smelter, Debari, Udaipur with process modifications and iron control practices is described in detail in this paper. Most of the modifications were made at different times as part of capacity enhancement campaigns that led to distinct advantages, thereby increasing both zinc production and recoveries. This smelter came into existence in 1968 with a humble beginning of producing 18,000 metric tonnes (MT) of zinc per annum, using the conventional batch hydrometallurgical roast-leach-electrowinning technology. Zinc production capacity was increased stepwise to 45,000 MT, 49,000 MT and 59,000 MT, by making suitable process modifications and adopting new technologies, particularly in the leaching section. During these modifications, the process of iron separation as Moore cake was also changed to jarosite cake production. At present, jarosite is being disposed in a secured landfill at the Zinc Smelter, Debari (ZSD) and as Jarofix at the Chanderiya Lead Zinc Smelter (CLZS). As a result of subsequent in-house performance improvement and debottlenecking campaigns, this smelter could achieve further increases in production. Zinc production for the financial year 2005-06 was 81,000 MT.

Jan 1, 2006

Reaction between xanthate ions in solution and oxidized compounds present on the surface of galena to form lead xanthate is considered to be a side reaction not contributing to flotation, although accounting for some consumption of reagent. The direct reaction of lead sulphide with xanthate and oxygen to form lead xanthate is the most significant to flotation. Coadsorntion of dixanthogen is also involved. Previous work has shown lead recovery in lead rougher flotation to be a function of m [H+] where: m = concentration of xanthate in solution rHl = hydrogen ion concentration. A plausible explanation for this relationship is suggest-ed. Likewise, the experimental findings that the amount of xanthate adsorbed under certain conditions is a function of m'[H+] are explained in terms of reaction between xanthate ions and soluble basic lead salts such as PbO.PbS04? It is also shown that m[H+] should have a constant value in lead cleaners operating at a higher pH than the roughers. This conclusion is confirmed by plant data, and the value of the constant agrees well with the calculated value. The finding is useful in mill control.

Jan 1, 1965

By Troy Boisjoli

Since its discovery in February 2014, the Arrow Uranium Deposit has undergone rapid development through aggressive and systematic drilling programs and is now being progressed through advanced engineering and permitting. Based on the 2018 NI 43-101 Technical Report, the Probable Mineral Reserve estimate totals 234.1 million (“M”) pounds (“lbs”) triuranium octoxide (“U3O8”), contained in 3.43 M tonnes at an average grade of 3.09% U3O8. The proposed processing plant at the Rook I Project (the “Project”) will be capable of producing up to 31 M lbs of U3O8 per year, with a projected mine life of nine years based on the Probable Mineral Reserve estimate, although NexGen is permitting a 24-year operating life at the Project assuming the majority of Inferred Mineral Resources are upgraded to Indicated Mineral Resources with continued mineral resource development drilling. The Project will be developed through transverse and longitudinal longhole mining methods, pairing primary and secondary stoping techniques with a high degree of equipment mechanization which will provide a combination of good productivity, high extraction, and stable back support. This next generation of uranium operations combines the use of advanced tele-remote equipment and instrumentation with a low-cost bulk mining method and a best-in-class tailings management practice, effectively reducing operating costs and setting a new standard for elite environmental and social practices.

Jan 1, 2020

By E. A. Sobering

Hydraulic filling or sand filling is a system used to fill underground excavations with a dense pulp. Milltailings are commonly used. The resultant fill, after being placed and de-watered, is known as hydraulic fill. These fills have been effectively used to (a) provide immediate support of the workings place during stoping; (b) .facilitate the recovery of pillars; (c) limit surface damage by subsidence; (d) permit the mining of parallel hanging-wall orebodies; (e) stabilize the ground in mines, thereby reducing the rock burst hazard; (f) control and prevent mine fires; and (g) solve tailings disposal .problems. The various uses of hydraulic filling have been developed during the last ninety years. In 1864 it was employed only to control surface subsidence. Since then, this system has been successfully applied to meet specific ground support problems. Methods of handling mine-fill derived from a source outside the stope include transportation ?Of the material by hand, mechanical, pneumatic, and hydraulic means, or a combination of these methods. The hydraulic method has many advantages not found in the others; a significant advantage is the low compressibility of the material when compared to other mine-fill material. The hydraulic filling operation includes the .preparation and transportation of the pulp. The underground practices in .placing the fill vary from mine to mine. The chief reason, formerly, for using hydraulic fill was the exceptional support it provided, but recently it has proven an important means of reducing mining costs. This is especially true where labour is a large part of an alternative method, or where timber consumption is greatly reduced. The indirect benefits of hydraulic filling are probably as important as the direct benefits, and few important disadvantages exist.

Jan 1, 1956

By P. G. Smith, A. Axiuk

The objective of this paper is to present, from a practical perspective, a review of the most relevant maintenance procedures that are accepted or prescribed to be the most effective in optimising service life potential and to ensure continued safe use of steel wire ropes for shaft mining applications. The paper will address the most common operational issues encountered in the care and operation of shaft ropes for both conventional drum hoists and multi-rope friction winders. For each distinct maintenance procedure presented, a limited amount of theory is discussed to identify the underlying mechanisms at play that must be addressed and to emphasize the logical basis for the recommended course of action. It is recognised that each installation is unique and that the recommended maintenance procedures may not always be practical or cost effective from an operations standpoint under select circumstances, however the intent remains to promote industry best practices for the knowledge and benefit of the mine hoisting community, from experienced maintenance personnel to new entrants to the industry alike.

Jan 1, 2023

By B. Voyzelle

The deterioration of highway and bridge infrastructure has received considerable attention in recent years because of the billions of dollars needed for repair and rehabilitation. A major factor contributing to this problem is the corrosion of steel reinforcement. Reinforcing steels with good corrosion resistance and relatively low price are therefore essential for maintenance, cost reduction and service-life extension of the steel-reinforced structures. This article describes the development of low-alloying steels that offers good corrosion resistance with reasonably low cost. Topics include steel microstructures, mechanical properties, corrosion performance, industrial applications and economic aspects.

Jan 1, 2005

By M. Abumiya, N. Onodera

Stabilization of arsenic via the precipitation of large-sized scorodite (FeAsO4·2H2O) particles usually involves the use of expensive autoclave systems operated under high temperature and pressure conditions. Alternatively, DOWA developed a novel scorodite synthesis process (DMSP®) wherein the Fe(II) ions in solution containing As(V) ions were oxidized by O2 gas under atmospheric pressure. In this process, crystalline scorodite particles were formed via the formation of a gel-like precursor containing Fe(II). Based on this concept, in this study, we have demonstrated the synthesis of scorodite particles by the addition of Fe(III)-containing solution to the experimental solution containing Fe(II) and As(V) ions, without the O2 gas oxidation process. Ferric sulfate (Fe2(SO4)3) was used as the source of Fe(III) ions. Results indicate the precipitation of scorodite particles, comparable to that of the O2 gas oxidation method.

Jan 1, 2014

By D. Beneteau, L. Feldman, D. Milne, A. Hyett, G. Snell

"Behaviour of rebar bolts subjected to combined shear and bending in underground potash mining applications is not well understood. An experimental investigation compared load applied to resin-grouted No. 25 metric rebar to theoretical load, calculated using elastic bending theory. Distributed optical sensing (fibre optic) technology allowed axial strain measurements at 1.25 mm increments along the length of rebar. Experimental procedure, data processing methods, and equipment improvements are needed for field applications of optical sensing technology. Goals were to adopt procedures for instrumenting rebar bolts, conduct tests, and develop data interpretation methods to measure field deformations and loads. ¦ KEYWORDS Fibre optic, Potash mine, Rebar bolts, Transverse load testing RÉSUMÉ On appréhende encore mal le comportement des boulons d’ancrage pour barres d’armature soumis au cisaillement et au cintrage pour un usage dans des mines de potasse souterraines. Une étude expérimentale compare la charge appliquée aux barres d’armature de diamètre n° 25 (25 mm en mesure métrique) enduites de résine époxy à la charge théorique, calculée à l’aide de la théorie de la flexion élastique. La technologie de détection optique distribuée (fibre optique) a permis d’effectuer des mesures de la contrainte axiale à des différentielles de 1,25 mm sur toute la longueur de la barre d’armature. Pour des applications sur le terrain de la technologie de détection optique, il faut envisager une procédure expérimentale, des méthodes de traitement de données et une amélioration de l’équipement. Les objectifs établis consistent à adopter des procédures d’instrumentation des boulons d’ancrage pour barres d’armature, à effectuer des essais et à mettre au point des méthodes d’interprétation des données pour mesurer les déformations et les charges sur le site. ¦ MOTS CLÉS boulons d’ancrage pour barres d’armature, essai par charge transversale, fibre optique, mine de potasseINTRODUCTION Resin grouted rebar bolts are commonly used in potash mines in the province of Saskatchewan, Canada, in areas where shear deformation is observed in the rock, or where potentially unstable ground is present, including locations such as clay seams. Opportunities to observe deformations of rebar, as shown in Figure 1, are rare because it is unusual in underground potash mining to excavate supported ground. In this situation, a block of potash containing a rebar bolt had failed."

Jan 1, 2019

By I-H. Jung, J. Kim, B. Konar

"The usage of FeNdB permanent magnet, containing Rare earth elements (REEs), is steeply increasing with its demand for wind-turbine and electrical vehicle. The improvement and recycling of the permanent magnet require good understanding of chemistry of all constituent elements. In order to understand the chemical interactions between REEs and Fe, all Fe-RE binary systems have been critically assessed and optimized based on reliable literature data. The Modified Quasichemical Model and Compound energy formalism is employed to model the liquid phase and the solid solutions present in the binary systems respectively. The enthalpy of the liquid and the intermetallic phases showed a systematic trend along the lanthanide series. This helped to mitigate the discrepancies in literature data and also to predict the binary interactions between some less well investigated Fe-RE binary systems. INTRODUCTIONRare Earth elements (REEs) are a group of seventeen elements (including Scandium, Yttrium and the lanthanide series) that exhibit same characteristic chemical and physical properties. These properties make them valuable to the electronic, appliance, green technology, weapon and medical device manufacturing industries. Compounds of REE with other metals (like Co, Fe, Ni etc.) have unique properties of luminescence, thermal and electrical conductivity, magnetism and ability to act as catalysts and polishing compounds (Gschneidner ,2011).They are not only indispensable for some electronic gadgets of today, like computers, music systems, mobile devices, televisions and MRI machines, but also holds a key to more greener technology of the future. They contribute to the development of more efficient and environment friendly version of everyday products such as cars and light bulbs. REE compounds revolutionized the magnet industry by making them smaller and more powerful with increased longevity, and high temperature workability, which are used in motors and generators that power electronics, telecommunications, electric automobiles and turbines(Humphries, 2011)."

Jan 1, 2012

By M. B. Dusseault, A. Pirayehgar

"There is concern that hydraulic fracturing (HF) near an existing critically stressed fault could trigger slip and generate a seismic event of significance. To this end, a mathematical discontinuum model representing a naturally fractured rock (NFR) mass containing a fault is created, and fault slip response to fluid injection is studied. UDECTM is used as a Discrete Element Method (DEM) approach to define the seismic moment, and also to assess the influence of injection and slip on further shear slip propagation. In most of the simulations, slip and dilation take place along a number of oriented fracture surfaces, so it is reasonable to assume that in a real case, microseimic emissions would accompany each slip “event”. The moment magnitude scale (Mw) is used to measure the size of the microseismic event in terms of the energy released. Seismic moment is a measure of the total energy (work) released during a seismic event and is used to measure its size. From another aspect, the injection energy is calculated as the total energy required for achieving the hydraulic fracturing; this is viewed as energy to open fractures against the ambient stress field and much of it is potential stored energy that can be released and create discontinuities (work of fracture), deformations (W=F·d), heat and radiated seismic energy. A small amount of the total released energy is transformed to radiated seismic energy and another small amount results in tensile fractures. Fracture energy is used to calculate the work required to create fracture surfaces. Comparing the energy release by fracturing or seismic events indicates their contribution to the total amount of released energy or total work. The amount of energy associated with the stick-slip event is small compared with the overall work done to generate the distortions (i.e. increases in aperture by forcing them open) in the rock mass, and much of the energy in slip is lost as heat from the plastic deformation, rather than as radiated seismic energy.Microseismic monitoring shows the spatial distribution and magnitude of seismicity associated with slip of bedding planes and natural and incipient fractures. Work calculations have been undertaken to look at the various sources of energy storage (elastic strain energy) or dissipation (slip), and likely the energy losses from viscous dissipation could be addressed as well, helping to clarify HF processes in NFRs."

Jan 1, 2015

By H. Kudelka

Copper electrowinning at Duisburger Kupferhuette was introduced in March 1975. The electrowinning plant has a capacity of 10,000 mT of copper cathodes a year. The cuprous oxide feed material is an intermediate product of the treatment of the leach solutions, originating from chloridizing roasting of pyrite cinders. This material is characterized not only by a wide spectrum of accompanying impurities, but also by an unusually high level of precious metals. As the priority set was the production of high-purity cathodes. there was a need for developing a process which would be suited to treat complex leach liquors . The process adopted consist s of an oxidizing leach in spent electrolyte, followed by two- stage purification, By this means. a low- acid pregnant copper electrolyte is obtained free of elements detrimental to copper quality. Electrowinning is carried out at a current density of 200 A / m2 in the presence of 10 g/l zinc. The electrowon copper has a conductivity of at least 101.4% lACS and a softening temperature not exceeding 200°C, which makes it a suitable product for continuous casting and dip ?forming.

Jan 1, 1977

By V. G. Papangelakis, A. Dani

"Alkaline pressure oxidation, particularly in the presence of trona as additive, can be used to oxidize high carbonate refractory gold ores as it prevents the formation of CO2 in the autoclave. However, the presence of silica in the ore can lead to the encapsulation of pyrite due to the solubility of silica in alkaline solutions and its subsequent reprecipitation on the reacting pyrite surface, leading to the formation of a passive layer. This fundamental study investigates the chemical composition and thickness of the passive layer on a rotating pyrite disk using XPS and SEM, as a function of process conditions at 230°C, in an aqueous slurry containing silica sand, sodium carbonate and calcium carbonate under 100 psi of oxygen overpressure.INTRODUCTIONAlkaline pressure oxidation (POX) has been used successfully to treat high carbonate refractory gold ores, which contain carbonates in addition to sulphides, most notably at Mercur and Goldstrike mines operated by Barrick Gold. There are several advantages to using alkaline POX over its acid counterpart, especially due to high carbonate content. First, it eliminates the production of CO2 in the autoclave without resorting to pre-acidification, which allows for high oxygen utilization. Second, alkaline POX suppresses the formation of elemental sulphur and intermediate sulphur oxyanions (such as thiosulphates and dithionates), which reduce gold recovery. Third, the use of sodium hydroxide or salts prevents the formation of anhydrite scale by forming soluble sodium sulphate. Other advantages are the use of cheaper materials of construction and the formation of non-acidic residue that do not require further treatment prior to cyanidation (Thomas, 2005).Sodium carbonate in particular is a promising reagent for alkaline POX because it was shown to significantly accelerate the kinetics of pyrite oxidation by molecular oxygen, when compared to other reagents such as sodium hydroxide, sodium borate and calcium hydroxide. This has been attributed to the following factors: a) the faster oxidation kinetics of Fe2+-CO3 complexes compared to Fe2+ oxidation, b) the buffering effect of carbonate ions on the acidic pyrite surface, and c) the increased solubility of oxidizing Fe(III) species due to carbonate complexation (Caldeira, 2010)."

Jan 1, 2012

By Andrew Gillam

Outline of Presentation ? AMEC overview ? Benchmarked companies ? GRI 3.1 Guidelines ? Best practice examples ? Report content and boundary ? Strategy and profile ? Environmental ? Social GRI G3.1 ? Gold Standard for Reporting ? GRI ? Global Reporting Initiative ? 1997 outgrowth of Coalition for Environmentally Responsible Economies (CERES) and UN Development Program (UNDP) ? Official collaborating centre of UNDP and works in collaboration with UN Global Compact ? Coalition of companies, business organizations, accounting firms, CSR consulting firms and nogovernmental organizations (NGOs) ? Mission: develop and disseminate globally applicable Sustainability Reporting Guidelines ? Now de facto CSR reporting standard; appeal lies, in part, with supported flexibility in reporting approach and scope ? Latest generation G3.1 (March 2011); includes expanded guidance for reporting on human rights, local community impacts and gender

Aug 1, 2013

By Martin Landwehr

"Dust samplers are based on different principles. The konimeter is based on the number of particles counted; mining applications are based on routine sampling; and the photometrical evaluation of samples is used after the pre-separation of particles above 5 micron by the mining konimeter. In special cases, the Draeger sampler is used for quantitative analysis. General trends are toward larger samples, concentration on a weight basis, fractionation into size groups by different techniques and an analysis of composition. Standards or TLVs already exist in all industries. Surface industries base their criteria on concentrations and quartz contents in particles below 5 micron. The mining industry uses the tyndalloscope routinely to determine concentrations; concurrent] y, the rock content, as deter-mined by ashing samples, is obtained by konimeter.Threshold limits are related to the rock content in respirable fractions and tyndallometrically determined concentrations. The TL Vs are based empirically on Landwehr's ""dust values,"" as agreed upon with the Mines Inspectorates. Recently, and in accurate sampling, dust samplers have been used that count the dust in two fractions -above and below 5 microns. Mineral composition is determined either for all minerais or just for quartz. In assessing the dust hazard by Landwehr's ""dust values,"" all minerais are taken into consideration; in coal dust sampling, however, only the quartz content is taken into account. Efforts are now being made to co-ordinate the different assessment methods, arriving at uniform MAC values in agreement with those of other countries."

Jan 1, 1969

By Riggin P. R.

"IntroductionIndustrial Relations combines two very important relationships - employee relations and union relations.Employee relations always come into play when people are hired to perform tasks. Because mineral processing plants cannot be operated successfully without people, at least not yet, if they ever will be, employee relations must exist in an operatingplant.If the employees choose to be represented by a union, then a relationship with the union as an institution also comes into play. It is very important to note that unionization does not mean that the employee relationship is replaced by a relationship with the union. The latter is superimposed on the former, but it does not replace it. Similarities and overlaps in the two relationships will be present, some of which are of fundamental importance. Nevertheless, they are two different relationships and the reader should bear this in mind when reviewing those parts of this chapter which discuss unionization, collective bargaining, collective agreements, and work stoppages.These two important relationships, which we have chosen to combine and call industrial relations, have crucial roles to play in the social system which interrelates people performing the necessary tasks involved in the operation and maintenance of a plant. The technological organization - equipment, process layout and so forth - and this social system are interdependent and complementary. This chapter attempts to show that the potential level of effectiveness of both the technological organization and the social system depends on the recognition and nurturing of this nexus between them.Occupational health and safety and training are subjects for another chapter. But, both of these have been critical and longstanding employee relations topics . They are destined to take on added importance in the future. As issues in collective bargaining, they are also attracting increasing attention in all union relations. It is hoped that the reader will not isolate from industrial relations those topics which are being dealt with in another chapter. They are very much a part of it and we cannot refrain from making some reference to them."

Jan 1, 1989

By H. E. Pawson

Giant Yellowknife is located 600 air miles north of Edmonton on the north shore of Great Slave Lake in the Northwest Territories. In its 24 years of operation some 7,730,000 tons of ore have been treated to yield $175,000,000 worth of gold.The gold ore occurs at irregular intervals throughout a fold-like sericite schist zone cutting Precambrian rocks. The ore is characterized by 40 to 80% quartz - carbonate and about 10% pyrite and arsenopyrite. Considerable amounts of stibnite and antimony sulpho-salts are also present. Gold is finely divided in the native state existing in complex association with the sulphides. In most instances stibnite is barren but minor values are evident on occasion. Visible native Fold, quite prevalent in the early operating years, is, practically non-existent today. It was readily apparent from mineral dressing investigations conducted in .1944 that Giant ore would be difficult to treat. By 1948 a flow sheet had been established and operations began. In the ensuing years, changing ore characteristics necessitated modifications to some process steps and complete abandonment of others. By 1962 the major metallurgical problems were solved and all that remained was the refining of operating performance to its highest level.With one or two exceptions today's operation follows the practice established by 1962 (Fig. 1 - Flowsheet).

Jan 1, 1973

By Jürgen Antrekowitsch, Gerardo R. F. Alvear Flores, Mehmet Ayhan, Christoph Zschiesche

Synergies between copper and lead extractive metallurgical processes enable the processing of a broad range of polymetallic materials. However, this complexity also brings some challenges expressed in terms of complex intermediates and final products. For instance, based on the limited solubility of Cu and Ni in crude lead bullion additional phases will appear during the crystallization of the melt. Beyond the need for continuous optimization of metallurgy the control of phase solidification is a further important pillar to achieve a more efficient process by minimizing the amount and cycles of reverts. This paper describes the microscopy study of one of the most relevant intermediate in the Cu and Pb metallurgy, the Cu based alloy and highlights the importance of applying a well-controlled cooling sequence to improve the overall process efficiency. INTRODUCTION One of the key aspects in Aurubis’s 2025 vision is to move towards the implementation of a multi metal recovery strategy. The implementation of this new multi metal vision is supported by the long tradition of the company, founded in 1866 as Norddeutsche Affinerie, and further developed by adopting modern copper smelting and lead smelting technologies for the processing of primary and secondary materials. The combination of these assets have already build the basis for processing of complex materials in the copper and lead circuits implemented in Aurubis’s facilities. The addition of a new smelting facility, will enhance these capabilities. Aurubis current flowsheet combines Cu, Pb and Zn metallurgy. This includes primary smelting of copper concentrate, processing of secondaries (residues, slimes, slags) and recycling materials (scrap, shredder material, e-scrap). These broad range of materials contain not only the mentioned base metals but also a number of minor metals that requires to be properly managed to ensure efficient recoveries and quality of the targeted metals.

Jan 1, 2019

By C. Cutts, K. Wheatley

The Dragon Lake Zone (uranium prospect) comprises a N160º trending vein that is approximately 110 m long, up to 5 m wide and from 1 to 40 m high. The zone is mostly within altered sandstone of the Fair Point Formation, the basal unit of the Paleoproterozoic Athabasca Group, but it also extends downward (up to 3.5 m) into basement rocks that occupy the northerly trending Maybelle River Shear Zone (MRSZ). This subvertical shear zone separates graphitic paragneiss and weakly deformed granitoid rocks to the east from non-graphitic paragneiss and foliated granitoid rocks to the west. The Dragon Lake Zone cuts across both the MRSZ and N060º-N070º-trending cross-faults that offset the shear zone but not the mineralized vein, which contains values up to 54.5% U over 50 cm core length. Strong chloritization occurs in graphitic paragneiss and sandstone adjacent to mineralization. Silica was depleted from the basement rocks and redeposited at the borders of the 5-15-m-wide alteration zone, as well as within overlying sandstone of the Manitou Falls Formation. There are minimal alteration effects in the overlying Lazenby Lake Formation. Geochemistry shows that the alteration zone in the Fair Point Formation is highly anomalous in metals, most notably in Ni, As, U, Pb, Co, and B. Clay within this zone is illitic and Fe-rich chlorite is also present. Brittle deformation is not as widespread or as well developed in the Fair Point Formation as it is in the overlying Manitou Falls Formation, which is extensively brecciated and contains some anomalous metal values.

Jan 1, 2013

By K. C. Marsden, B. Pesic

"Interest in the efficient production and recycling of rare earth elements has increased in recent years along with the prices of these elements. The molten LiCl-KCl eutectic is one ionic solvent which can be utilized for these purposes. The LiCl-KCl eutectic has also been selected as the electrolyte for focused research for advanced pyrochemical recycling processes for used nuclear fuel in several nations. Rare earth elements are fission products with notable neutron absorption characteristics, and thorough understanding of the properties and behavior of these elements is critical to their successful partition from the electrochemically-similar actinide elements. The number of research papers investigating individual rare earth elements has greatly expanded in the approximately 35 years since the last review. These research papers are presented in a variety of languages and technical formats, making data difficult to compare, and are sometimes contradictory. A review and summary of diffusion properties of rare earths in LiCl-KCl eutectic was performed, and the data translated to a common format for evaluation. INTRODUCTIONThe rare earth elements have experienced growing importance in recent decades due to their application in high technology, including optical lenses, lasers, high-temperature superconductors, improved alloys, high energy-density batteries, and powerful magnets for compact electronic devices. Their historic production methods and uses are detailed in several texts (Hampel 1971; Bautista &Jackson 1992; Gupta & Krishnamurthy 2005). A s the p rice o f these e lements has r isen in r ecent years, so has interest in their efficient production and possible recycling options. Rare earth oxides are concentrated through hydrometallurgical techniques, but the high thermochemical stability of their oxides precludes production of rare earth metals in aqueous systems. However, the wide electrochemical window and better control of pO2- in fused salt systems allows the production of these reactive metals from their halides or oxides. The high ionic conductivity and diffusivity of the molten ionic electrolyte allow high currents with limited resistive losses (Fray 1980). Electrolytic methods in fused salts are commonly adopted for the production of bulk rare earths in a variety of molten salt systems. Fluorides are sometimes proposed for oxide electrowinning processes due to ability to dissolve the rare earth oxide, reduced hygroscopic behavior, and the wider electrochemical separation between O2 and halide gas evolution (Mohan Das, Damodaran et al. 1988; Gibilaro, Pivato et al. 2011). However, in most electrolytic production processes, such as that for mischmetal, the rare earth oxides are converted to chloride prior to electrolysis in a chloride bath (Gschneidner Jr. & Eyring 1978; Sharma 1987). Of the chlorides, the LiCl-KCl eutectic is one specific medium in which metal production and production-related investigations have been conducted (Gschneidner J r. & Eyring 1978; Driscoll & Fray 1993). L iCl-KCl eutectic has the advantages o f h igh conductivity, but relatively low viscosity and operating temperature. The low operating temperature allows simpler design, with reduced energy consumption, salt volatility and cell corrosion."

Jan 1, 2012

By J. J. Brummer

"A reconnaissance geochemical survey, using the stream sediment technique, is described. The survey covered an area of about 400 square miles, in the Seal Lake area of central Labrador, underlain by basaltic flows, diabase and metadiabase sills, and sedimentary rocks. Previous work had indicated numerous small copper occurrences within the Seal Lake group of rocks. Stream sediments were tested for the readily extractable copper content and total heavy metal content. The results of the copper survey did not yield any new data on the distribution of copper mineralization. Results of the total heavy metal survey attracted attention to a remote portion of the area (Ten Mile Lake), which had hitherto been regarded as having no economic interest. The anomalous values found, suggested that zinc mineralization should occur in this region. Geological mapping indicated that the rocks exposed belonged to the Letitia Lake Group, which is older than the Seal Lake Group exposed to the east, which contains the copper mineralization of the district.Investigation of the area lead to the discovery of: (1) uneconomic lead-zinc mineralization; (2) radioactivity extending over a considerable area. Evaluation of the radioactive rocks led to the discovery of columbium-thorium mineralization in amphibolite and in diopside-actinolite schists along a contact with intrusive alkali syenite.Thus a geochemical survey, which was planned to evaluate a copper province, resulted in the discovery of lead-zinc-columbium-thorium mineralization."

Jan 1, 1960